jksimmet-v6-manual.pdf

Version 6.0

Steady State Mineral Processing Simulator

User Manual

JKSimMet - Version 6.0

Steady State Mineral Processing Simulator

by JKTech Pty Ltd

JKSimMet is a powerful tool for the analysis and simulation of mineral processing plantdata. As the program developers do not control data collection, analysis orinterpretation, it is the sole responsibility of the JKSimMet user to verify that the inputdata are accurate and that both process unit operating conditions and stream outputsare reasonable.

In no event will JKTech Pty Ltd be liable for direct, indirect, special, incidental orconsequential damages arising out of the use or inability to use the software ordocumentation.

Note: The detailed descriptions of the mathematical models in this manual are providedfor the information of the software licensees. These models are not public domain andthey may not be used in other software without written permission from or a licensingagreement with JKTech Pty Ltd.

40 Isles RoadIndooroopillyBrisbane QLD 4068AUSTRALIA

telephone: +61 7 3365 5842facsimile: +61 7 3365 5900email: info@jk tech.com.auweb: www.jk tech.com.au

JKTech Pty Ltd

All rights reserved. No parts of this work may be reproduced in any form or by any means - graphic, electronic, ormechanical, including photocopying, recording, taping, or information storage and retrieval systems - without thewritten permission of the publisher.

Products that are referred to in this document may be either trademarks and/or registered trademarks of therespective owners. The publisher and the author make no claim to these trademarks.

While every precaution has been taken in the preparation of this document, the publisher and the authorassume no responsibility for errors or omissions, or for damages resulting from the use of informationcontained in this document or from the use of programs and source code that may accompany it. In no eventshall the publisher and the author be liable for any loss of profit or any other commercial damage caused oralleged to have been caused directly or indirectly by this document.

Printed: March 2014 in Brisbane, Qld, Australia.

JKSimMet V6 Manual

© 2014 JKTech Pty Ltd

PublisherSpecial thanks to:

All of the JKTech and JKMRC staff and students who havecontributed in any way to the preparation of this document.

Managing Editor

Technical Advisors

Cover Design

JKTech Pty Ltd

Chris Bailey

Chris Bailey

Iain Crawford

Andrea Evers

Principal Author

Alister Grimes

Team Coordinators

Rolf Fandrich

Heather Miller

Debbie Gray

Assistant Author

Chris Keenan

Chris Keenan

JKSimMet V6 Manual4


Table of Contents

Foreword 11

Part I Overview 13

................................................................................................................................... 131 About JKSimMet V6

.......................................................................................................................................................... 13General Capabilities

.......................................................................................................................................................... 14How the Program Works

.......................................................................................................................................................... 16JKSimMet Simulation

.......................................................................................................................................................... 17JKSimMet Mass Balancing

.......................................................................................................................................................... 17JKSimMet Model Fitting & Analysis

................................................................................................................................... 172 Hardware & Operating System Requirements

................................................................................................................................... 183 Cautionary Tales

................................................................................................................................... 184 JKSimMet Structure

................................................................................................................................... 185 Available Models

................................................................................................................................... 196 JKSimMet Support

Part II Changes from Version 5 21

................................................................................................................................... 211 Summary of Main Changes

................................................................................................................................... 212 Precautionary Notes on Main Changes

................................................................................................................................... 223 Toolbar Changes

................................................................................................................................... 234 Creating Projects

................................................................................................................................... 285 Sieve Series and Survey Data Entry

................................................................................................................................... 316 The New Flowsheet Drawer

................................................................................................................................... 317 System Properties

................................................................................................................................... 338 Accessing Models

................................................................................................................................... 349 Equipment Manager

................................................................................................................................... 3510 Viewing and Entry of Stream Data

................................................................................................................................... 3611 Configurable Stream Overview

................................................................................................................................... 3712 Simulation Changes

................................................................................................................................... 3813 Simulation Manager

................................................................................................................................... 3914 Changes to Reporting

................................................................................................................................... 4015 Changes to Graphing

................................................................................................................................... 4116 Changes to Info Blocks

................................................................................................................................... 4317 Model Fitting Changes

................................................................................................................................... 4418 Mass Balancing Changes

Part III Installing JKSimMet 47

................................................................................................................................... 471 Contents of the Package

................................................................................................................................... 472 JKSimMet Installation

Part IV Learning JKSimMet 51

................................................................................................................................... 511 JKSimMet Basics

.......................................................................................................................................................... 51JKSimMet Data Structure

.......................................................................................................................................................... 52Available Equipment Items and Associated Models

5Contents


.......................................................................................................................................................... 56Building a Simulation Model

.......................................................................................................................................................... 57The Mouse and Cursor

.......................................................................................................................................................... 58The JKSimMet Windows

................................................................................................................................... 582 Building a New Project

.......................................................................................................................................................... 59The Steps to Simulation

.......................................................................................................................................................... 60JKSimMet Start Up

.......................................................................................................................................................... 61Creating the New Project

.......................................................................................................................................................... 63Adding Flowsheet Equipment

.......................................................................................................................................................... 72Add Connecting Streams

.......................................................................................................................................................... 78Define System Properties

.......................................................................................................................................................... 81Feeder Equipment Data

.......................................................................................................................................................... 83Select Equipment Models

.......................................................................................................................................................... 87Simulation

.......................................................................................................................................................... 89Viewing the Results

.......................................................................................................................................................... 94Viewing Individual Stream Data

.......................................................................................................................................................... 97Viewing Data for Multiple Streams

.......................................................................................................................................................... 99Finishing a JKSimMet Session

................................................................................................................................... 993 Working with an Existing Project

.......................................................................................................................................................... 100Selecting the Flowsheet to Use

.......................................................................................................................................................... 101Working with the Simulation Manager

.......................................................................................................................................................... 108Using Model Based Groups for Simulations

.......................................................................................................................................................... 111Simulating Changes in Operating Conditions

.......................................................................................................................................................... 116Working with Configurable Equipment Manager

.......................................................................................................................................................... 120Defining Stream Data Info Blocks

.......................................................................................................................................................... 125Defining Equipment Info Blocks

................................................................................................................................... 1294 Summary

Part V Using JKSimMet 131

................................................................................................................................... 1311 JKSimMet Description

.......................................................................................................................................................... 132JKSimMet Model Types

.......................................................................................................................................................... 134JKSimMet Capabilities

.......................................................................................................................................................... 135JKSimMet Constraints

.......................................................................................................................................................... 135JKSimMet Expandability

.......................................................................................................................................................... 135Definition of Terms Used in JKSimMet

................................................................................................................................... 1372 The JKSimMet Menus and Toolbars

.......................................................................................................................................................... 138The Main JKSimMet Menu

.......................................................................................................................................................... 139The File Menu and Main Toolbar

.......................................................................................................................................................... 140The Edit Menu

.......................................................................................................................................................... 143The View Menu

.......................................................................................................................................................... 145The Flowsheet Menu and Toolbar

.......................................................................................................................................................... 149The Balance, Fitting and Simulate Toolbar

.......................................................................................................................................................... 150Drawing Toolbar

.......................................................................................................................................................... 152The Tools Menu

.......................................................................................................................................................... 153The Help Menu

................................................................................................................................... 1533 JKSimMet Windows

.......................................................................................................................................................... 153Configurable Equipment Manager

.......................................................................................................................................................... 154Config Graph Window

.......................................................................................................................................................... 157Configurable Stream Overview Window

.......................................................................................................................................................... 158Information Blocks

.......................................................................................................................................................... 159Model Windows

.......................................................................................................................................................... 160Property Windows

.......................................................................................................................................................... 162Reporting to Excel Window

.......................................................................................................................................................... 163Simulation Manager Window

.......................................................................................................................................................... 164Simulation Window

.......................................................................................................................................................... 165Stream Windows

.......................................................................................................................................................... 171The Equipment Window

JKSimMet V6 Manual6


.......................................................................................................................................................... 172The Session Window

.......................................................................................................................................................... 175The Sieve Series Window

.......................................................................................................................................................... 175The Survey Data Window

.......................................................................................................................................................... 176The System Properties Window

................................................................................................................................... 1774 Building and Manipulating a Flowsheet

.......................................................................................................................................................... 177Loading an Existing Project

.......................................................................................................................................................... 178Creating a New Project

.......................................................................................................................................................... 179Loading an Existing Flowsheet

.......................................................................................................................................................... 180Creating a New Flowsheet

.......................................................................................................................................................... 181Defining the Flowsheet Name

.......................................................................................................................................................... 181Deleting a Flowsheet

.......................................................................................................................................................... 182Building the Flowsheet - Equipment

.......................................................................................................................................................... 184Building the Flowsheet - Streams

.......................................................................................................................................................... 187Annotating the Flowsheet

.......................................................................................................................................................... 189Information Blocks

................................................................................................................................... 1915 Editing the Flowsheet Data

.......................................................................................................................................................... 191Stream Structure

.......................................................................................................................................................... 192System Properties

.......................................................................................................................................................... 193Accessing the Equipment and Model Data

.......................................................................................................................................................... 194Editing the Model Data

.......................................................................................................................................................... 195Editing Equipment Data

................................................................................................................................... 1996 Using Simulation

.......................................................................................................................................................... 200Simulating Using the Simulation Window

.......................................................................................................................................................... 201Simulating Using the Simulation Manager

.......................................................................................................................................................... 210Accessing the Stream Data

.......................................................................................................................................................... 212Water in Simulation

................................................................................................................................... 2137 Viewing the Data - Summaries & Reports

.......................................................................................................................................................... 213Using the Configurable Stream Overview

.......................................................................................................................................................... 217Configuring Columns in the Stream Overview

.......................................................................................................................................................... 226Using the Reporting Feature

Part VI Mass Balancing 230

................................................................................................................................... 2301 Introduction to Mass Balancing

................................................................................................................................... 2302 Data Collection

................................................................................................................................... 2313 Background

................................................................................................................................... 2334 How the Mass Balancing Program Works

................................................................................................................................... 2355 Learning Mass Balancing

.......................................................................................................................................................... 236Model Types for Mass Balancing

.......................................................................................................................................................... 237Entering the Data

.......................................................................................................................................................... 240The SD Calculation Window

.......................................................................................................................................................... 243Standard Deviation Calculations

.......................................................................................................................................................... 246Preparation for Mass Balancing

.......................................................................................................................................................... 247Selecting Data

.......................................................................................................................................................... 251Selecting Components

.......................................................................................................................................................... 252Solution Controls

.......................................................................................................................................................... 254Water in Balancing

.......................................................................................................................................................... 255Running the Mass Balance

.......................................................................................................................................................... 259The Mass Balance Engine

.......................................................................................................................................................... 261Checking the Balance

................................................................................................................................... 2626 Presentation of Mass Balance Results

.......................................................................................................................................................... 263Configurable Stream Overview

.......................................................................................................................................................... 263Reports Function and Printing

.......................................................................................................................................................... 265Plotting Size Data Graphs

................................................................................................................................... 2677 Problems Related to Mass Balancing and Possible Solutions

7Contents


.......................................................................................................................................................... 267The Middlings Problem

.......................................................................................................................................................... 268The Infinite Division Problem

................................................................................................................................... 2688 Metallurgical Accounting

................................................................................................................................... 2699 References

Part VII Model Fitting 272

................................................................................................................................... 2721 Introduction to Model Fitting

................................................................................................................................... 2732 Background to Model Fitting

................................................................................................................................... 2733 How the Model Fitting Program Works

................................................................................................................................... 2744 Model Fitting as Applied in JKSimMet

................................................................................................................................... 2755 Preliminary Data Setup

.......................................................................................................................................................... 275Creating the Flowsheet

.......................................................................................................................................................... 275System Properties

.......................................................................................................................................................... 275Stream Specification

.......................................................................................................................................................... 276Data Input

.......................................................................................................................................................... 276Mass Balance Prior to Fitting

.......................................................................................................................................................... 277The Model Fitting Window

.......................................................................................................................................................... 284Master Slave Fitting

.......................................................................................................................................................... 286Checking the Fit

.......................................................................................................................................................... 287Presentation of Model Fitting Results

.......................................................................................................................................................... 291Problems Related to Model Fitting and Possible Solutions

.......................................................................................................................................................... 292References

Part VIII Model Descriptions 294

................................................................................................................................... 2941 General Models

.......................................................................................................................................................... 294Ore Feeder (1300)

.......................................................................................................................................................... 295Water Feeder Models (1251 & 1252)

......................................................................................................................................................... 295Model Description - General

......................................................................................................................................................... 295Required % Solids - Standard Model

......................................................................................................................................................... 296Water Addition - Standard Model

......................................................................................................................................................... 297Model Limitations

......................................................................................................................................................... 297References

.......................................................................................................................................................... 298Hydrocyclone Models (200, 201)

......................................................................................................................................................... 298Desciption

......................................................................................................................................................... 298Equations

......................................................................................................................................................... 301Symbols

......................................................................................................................................................... 302Restrictions

......................................................................................................................................................... 305Printouts

......................................................................................................................................................... 305Summary

......................................................................................................................................................... 306Fitting the Cyclone Model (200)

......................................................................................................................................................... 307Fitting the Nagesw ararao Fines Model (201)

......................................................................................................................................................... 307References

.......................................................................................................................................................... 308Narasimha-Mainza Cyclone Model (221)

......................................................................................................................................................... 308Description

......................................................................................................................................................... 308Equations

......................................................................................................................................................... 311Symbols

......................................................................................................................................................... 312Printout

......................................................................................................................................................... 313Restrictions

......................................................................................................................................................... 315Summary

......................................................................................................................................................... 315Fitting the Cyclone Model 221

......................................................................................................................................................... 317References

.......................................................................................................................................................... 317Screen Models (215, 230 & 235)

......................................................................................................................................................... 317Kavetsky Single Deck Screen Model (230)

......................................................................................................................................... 317Model Description

......................................................................................................................................... 319Model Equations

JKSimMet V6 Manual8


......................................................................................................................................... 321Single Deck Model Printout

......................................................................................................................................... 321Symbols

......................................................................................................................................... 322Know n Restrictions

......................................................................................................................................... 322Parameter Fitting the Screen Model

......................................................................................................................................... 324Regression Model Parameters

......................................................................................................................................... 325References

......................................................................................................................................................... 325Double Deck Screen Models (215 & 235)

.......................................................................................................................................................... 325Eff. Curves (210, 211, 212, 213, 203 & 240)

......................................................................................................................................................... 325Simple Eff iciency Curve (210, 212)

......................................................................................................................................... 325Model_Description

......................................................................................................................................... 325Model Equations

......................................................................................................................................... 326Fitting the Simple Eff iciency Curve

......................................................................................................................................... 326Simple Eff iciency Curve Printout

......................................................................................................................................................... 326Simple Eff iciency Curve - Water & Fines (211, 213)

......................................................................................................................................... 326Model Description

......................................................................................................................................... 327Model Equations

......................................................................................................................................... 327Fitting the Simple Eff iciency - Water & Fines

......................................................................................................................................... 328Simple Eff iciency Curve (Model 211) Printout

......................................................................................................................................................... 328Splined Eff iciency Curve (Model 203)

......................................................................................................................................... 328Splined Eff iciency Curve (Model 203) Description

......................................................................................................................................... 328Splined Eff iciency Curve (Model 203) Equations

......................................................................................................................................... 328Fitting the Splined Eff iciency Curve (203)

......................................................................................................................................... 329Splined Eff iciency Curve (Model 203) Printout

......................................................................................................................................... 329Symbols for Splined Eff iciency Curve Model (203)

......................................................................................................................................... 329Know n Restrictions

......................................................................................................................................................... 330References

.......................................................................................................................................................... 330Eff. Curve Variable D50c (Model 251)

......................................................................................................................................................... 330Model Description

......................................................................................................................................................... 330Model Equations

......................................................................................................................................................... 331Efficiency - Variable d50c (Model 251) Printouts

......................................................................................................................................................... 331Symbols

......................................................................................................................................................... 331Know n Restrictions

......................................................................................................................................................... 332Fitting

......................................................................................................................................................... 332References

.......................................................................................................................................................... 332Simple Combiner Model (800)


......................................................................................................................................................... 334Symbols


......................................................................................................................................................... 334References

.......................................................................................................................................................... 3342 Way Simple Splitter Model (810)


......................................................................................................................................................... 336Symbols


......................................................................................................................................................... 336References

.......................................................................................................................................................... 3362 Way Volumetric Splitter Model (812)


......................................................................................................................................................... 338Symbols


......................................................................................................................................................... 338References

.......................................................................................................................................................... 338Water & Solids 2-Way Simple Splitter (813)


......................................................................................................................................................... 340Symbols


......................................................................................................................................................... 340References

.......................................................................................................................................................... 3403 Way Simple Splitter Model (870)


......................................................................................................................................................... 342Symbols


9Contents


......................................................................................................................................................... 342References

................................................................................................................................... 3422 Comminution Models

.......................................................................................................................................................... 343Crusher Models (400 and 405)

......................................................................................................................................................... 343Model Description (Anderson/Aw achie/Whiten)

......................................................................................................................................................... 345Model Equations

......................................................................................................................................................... 346Ore Breakage Characterisation

......................................................................................................................................................... 346Breakage Distribution Parameter

......................................................................................................................................................... 348Breakage Parameters

......................................................................................................................................................... 348Crusher Pow er Predictions

......................................................................................................................................................... 351Crusher Model (400/405) Printout

......................................................................................................................................................... 351Symbols


......................................................................................................................................................... 352Fitting the Crusher Model

......................................................................................................................................................... 354Regression Modelling

......................................................................................................................................................... 354Model Testing

......................................................................................................................................................... 354References

.......................................................................................................................................................... 354Rod Mill Model (410)


......................................................................................................................................................... 355Model Equations

......................................................................................................................................................... 358Rod Mill Model Printout

......................................................................................................................................................... 358Symbols


......................................................................................................................................................... 360Fitting the Rod Mill Model

......................................................................................................................................................... 360References

.......................................................................................................................................................... 360Perfect Mixing Ball Mill (Model 420)


......................................................................................................................................................... 362Model Equations

......................................................................................................................................................... 365Ball Mill Model Printout

......................................................................................................................................................... 365Symbols


......................................................................................................................................................... 367Fitting the Perfect Mixing Ball Mill Model

......................................................................................................................................................... 367Table of Appearance Functions

......................................................................................................................................................... 369References

.......................................................................................................................................................... 370SAG Mill (Model 430)


......................................................................................................................................................... 371Equations - Particle Breakage

......................................................................................................................................................... 374Equations - Mass Transfer and Discharge

......................................................................................................................................................... 376Prediction of AG/SAG Mill Pow er Draw

......................................................................................................................................................... 380SAG Mill Printout

......................................................................................................................................................... 381Symbols


......................................................................................................................................................... 383Fitting the Autogenous & SAG Mill Models

......................................................................................................................................................... 385References

.......................................................................................................................................................... 385Size Converter Model (490)

......................................................................................................................................................... 385Introduction

......................................................................................................................................................... 385Model Details

......................................................................................................................................................... 385Fitting the Size Converter


.......................................................................................................................................................... 386Variable Rates SAG Model (435)

......................................................................................................................................................... 386Introduction

......................................................................................................................................................... 386Scaling Approach

......................................................................................................................................................... 387Slurry Holdup Model

......................................................................................................................................................... 387Variable Rates Model

......................................................................................................................................................... 390Effect of Key Parameters

......................................................................................................................................................... 396Parameter Fitting - Variable Rates Model

......................................................................................................................................................... 398Variable Rates for Simulation & Design


......................................................................................................................................................... 401Variable Rates SAG Model Printout

JKSimMet V6 Manual10


......................................................................................................................................................... 402References

.......................................................................................................................................................... 403High Pressure Grinding Rolls (Model 402)

......................................................................................................................................................... 403Introduction

......................................................................................................................................................... 404Model Structure

......................................................................................................................................................... 405Breakage Processes

......................................................................................................................................................... 407Compressed Bed Breakage Function

......................................................................................................................................................... 407Throughput

......................................................................................................................................................... 410Pow er Draw

......................................................................................................................................................... 413HPGR Model Printout

......................................................................................................................................................... 414Fitting the HPGR Model

......................................................................................................................................................... 415Scaling the HPGR Model


......................................................................................................................................................... 417Nomenclature

......................................................................................................................................................... 418Acknow ledgements

......................................................................................................................................................... 418References

.......................................................................................................................................................... 419Size Degradation (Model 480)

......................................................................................................................................................... 419Introduction

......................................................................................................................................................... 419Model Structure

......................................................................................................................................................... 421Degredation Model Printout

......................................................................................................................................................... 421Fitting the Degredation Model


Index 422

JKSimMet V6.0

Steady State Simulation Software for Comminution andClassification Operations in the Mineral Processing Industry

11Foreword


Part

I

Version 6.0.1 - March 2014

Overview 13

1 Overview

Overview This section provides a broad overview of the JKSimMet program and its

capabilities. It includes a chapter on the hardware and operating system

requirements plus some information about program structure and the

included process models.

1.1 About JKSimMet V6

About this

Program

This chapter covers some of the more general information relating to

JKSimMet V6.

1.1.1 General Capabilities

General

Capabilities

JKSimMet V6.0.1 is a comminution circuit simulator that runs on the Intel

Pentium family of computers under Windows 8, Windows 7, Vista or XP. It

gives engineers the ability to design and simulate comminution circuits. More

specifically, it allows engineers to:

create a circuit using a graphics based interface;

enter model and stream feed data;

simulate the circuit;

view the results.

Main Features JKSimMet is intended for use by plant engineers not necessarily skilled in

either modelling or simulation. For that reason, it has been written to operate

in a user-friendly manner. The user selects options from menus or lists and

builds flowsheets on the screen. This removes the need for specialized

computer skills while maintaining flexibility.

The main features of JKSimMet are:

graphical user interface;

flowsheet specified interactively on the graphics screen;

a wide range of models that can be selected from the built-in library;

JKSimMet will also in the future have the ability to add new user-

defined comminution circuit models to the program;

model parameters that can be fitted by the user;

simple data transfer between JKSimMet and other programs such as

MS Excel for data preparation and manipulation.

JKSimMet has been designed primarily as a powerful aid to engineers. The

principal application of JKSimMet for many users will be to carry out process

analysis and optimization of existing circuits.

JKSimMet is also extremely useful for conducting conceptual design studies,

where the purpose is to assess the suitability of different flowsheets to achieve

a desired performance objective.

Version 6.0.1 - March 2014About JKSimMet V6


1.1.2 How the Program Works

About JKSimMet JKSimMet is a general-purpose computer software package for the analysis

and simulation of mineral processing operations. The package is designed to

service the diverse needs of plant and development metallurgists, who need

modern process analysis techniques to characterise plant behaviour and

design engineers, who require accurate process simulation models to facilitate

the evaluation of various plant designs.

JKSimMet integrates all tasks associated with optimisation, design and

simulation, including the storage and manipulation of models, data and

results, within one package. It is fully interactive and operates with high-

resolution colour graphics capabilities. These graphics facilitate the display of

detailed plant flowsheets and accompanying information.

Building a

Simulation

Model

The engineer using JKSimMet proceeds through a series of tasks:

building a flowsheet diagram of the processing plant on the computer

screen

assigning characteristics to the various process units and material flows

of the simulation model

simulating the flow of materials through the simulated plant (or a

subsection of the plant).

reviewing and presenting the results.

Once a model has been built, the engineer can alter the design and change the

parameters as required until a satisfactory design has been achieved, or an

optimum operating condition is arrived at, in the case of an existing plant.

The results may be graphed, printed in summary form and stored on hard

disk or archived to a CD or DVD. The results can also be transferred to other

suitable programs via the clipboard.

Simulation is based on the ability to build a model that is representative of a

real system. The behavior or characteristics of the model must be similar to the

characteristics of the real system. In order to build the model the engineer

must analyze the overall plant and break it down into a number of sections

(circuits), in such a way that these circuits are easily understandable and

identifiable. The circuits are interconnected to form the total system.

The data structure within JKSimMet V6.0.1 consists of the following:

Project A project is the container in which the user stores all of the data related to a

particular body of work. The project contains one or more flowsheets (circuits)

and the associated equipment units and stream data.

Flowsheet A flowsheet is a graphical representation of a complete processing plant or a

discrete section of that plant. The flowsheet can have internal recirculating

streams. However, if a stream recirculates to a previous section of the plant

that has been represented using a separate flowsheet, then this stream would

be treated as an output stream from the current flowsheet.

A flowsheet may be increased in size to represent a large, complex circuit.

Either the complete flowsheet or selected sections of it may be simulated, mass

balanced or model fitted.

Note that this capability to select items for inclusion in simulation, modelling

or mass-balancing replaces the circuit-oriented flowsheets required by the

Version 6.0.1 - March 2014 About JKSimMet V6

Overview 15

DOS versions of JKSimMet.

Equipment and

Ports

Version 5 introduced a new concept. Each flowsheet equipment icon

represents a discrete processing stage in your flowsheet. It can represent a

single equipment item or several identical items in parallel. Each icon (or

equipment unit) will have a single combiner or feed port plus one or more

product ports. These feed and product ports facilitate the connections (by

means of streams) between the various equipment icons on your flowsheet.

The reason for this change in structure was to allow for the future

development of a dynamic simulator. This approach also allows for pipes and

conveyors to be modelled as pieces of equipment.

Units and Streams still provide a convenient way of thinking about

flowsheets and for practical purposes, the terms equipment and ports can be

used interchangeably with units and streams.

Units

(Equipment

Items)

A unit is any type of unit process such as a ball mill or a hydrocyclone

classifier. JKSimMet allows you to select the appropriate unit from an

extensive list of processing unit types and to display their pictorial

representations (icons) on the screen. These units are identified within the

system by a name, which is specified by the user. You can also specify the

orientation of the units (i.e. whether the feed port is to the left and product

port(s) to the right or vice versa) and the position of units on the flowsheet

diagram.

Streams

(Connectors

between Ports)

A stream is a description of any flow of material. The description is usually in

terms of solids flow rate, water flow rate and particle size distributions (plus

assays for mass balancing, if required). The stream connections between units

are made by drawing lines connecting the appropriate feed and product ports

on the units. JKSimMet automatically checks to ensure that the stream

connections are valid. Each stream or port is named by JKSimMet as a

combination of its equipment name and port name. The user can edit the

equipment names as required but the port names for each piece of equipment

are fixed.

Specifying

Flowsheet Data

Once the flowsheet has been drawn the engineer must provide data for each

process unit and also provide raw data in the form of flows and size

distributions for the streams in the circuit. This is done by stepping through

the process units and the streams one-by-one, adding circuit data and

building up an annotated description of the modelled processing circuit on

the screen. The unit data for the process equipment may come from previous

experience, from a design database or they may be derived from plant data.

The sizing component of the stream data can be entered in one of three size

distribution formats, depending on the preferences of the user. The engineer

can review or correct these data at any time after making the initial entries.

Flowsheet

Simulation

Once the flowsheet has been specified and the required unit and stream data

have been entered, the simulation can be run. The results of the simulation are

stored and can be displayed on the screen or printed as required. The

following options are available for examining the results:

view the detailed data in the equipment and port data windows,

view summary data for equipment and ports via data information

blocks,

view summary data in overview tables,

18

Version 6.0.1 - March 2014About JKSimMet V6


view the size distribution data plotted as graphs on the screen,

generate configurable reports at summary or detailed level for export to

MS Excel or the clipboard,

copy-and-paste the data into other programs (eg. MS Excel) via the

clipboard

print the flowsheet to a Windows compatible printer or to a file.

Recorded data include:

flow rates of solids and water

percentage solids

pulp densities

full particle size distributions.

After analysis of the results, the user can alter the flowsheet, adjust the

equipment parameters or port data and repeat the simulation process until a

satisfactory result is obtained.

Flowsheet

Selection

A new capability that was introduced with V5 is that a subset of the flowsheet

may also be selected for simulation, mass balancing or model fitting.

1.1.3 JKSimMet Simulation

Available

Process Models

JKSimMet performs steady state simulation of comminution and related

operations. Process models of the following units are available:

particle size reduction devices e.g. crushers, SAG mills, ball mills;

particle size classification devices e.g. hydrocyclones and screens

separators e.g. 2 and 3 product splitters;

combiners e.g. pump, pump sump, sump;

stream source e.g. feeder, water feeder;

stream sink e.g. final product.

New process models can readily be incorporated into JKSimMet by JKTech.

This is done by defining their characteristics as steady state models and

creating an icon for each to represent them on the screen.

Simulation

Limits

It is important at the outset to understand what JKSimMet will and will not

do. JKSimMet will predict the performance of a circuit within the limitations of

the data and the models selected. JKSimMet will not determine of its own

accord the best circuit, the best operating conditions or the changes that are

required to ensure that a circuit operates efficiently. JKSimMet does not allow

process constraints to be specified.

Provided that the data used in the process models are relevant to the ore being

studied, JKSimMet can be used to generate detailed design information. Until

experience is gained in detailed design studies using JKSimMet, it is

recommended that design tasks be carried out in consultation with JKTech.

Simulation

Constraints

The operator has an essential role in deciding the conditions to be simulated

and in critically assessing the simulation predictions. This is a deliberate

result of the design philosophy of JKSimMet, which places considerable

Version 6.0.1 - March 2014 About JKSimMet V6

Overview 17

emphasis on the process experience and knowledge of the operator.

This point is amplified later under the topic JKSimMet Constraints , and

the reader is strongly advised to keep these points in mind when using the

system for simulation analysis.

1.1.4 JKSimMet Mass Balancing

JKSimMet enables users to mass balance comminution circuits on both a size

and assay basis simultaneously. It allows engineers to:

create a circuit using a graphics based interface;

enter stream data and calculate appropriate standard deviations;

mass balance the circuit;

view the results.

Mass Balancing

Limitations

JKSimMet will mass balance experimental data to produce a consistent data

set. It will not make bad data better, but will show the quality of the data and

where more care is needed in collecting the data.

1.1.5 JKSimMet Model Fitting & Analysis

JKSimMet allows users to perform many areas of data analysis within the

program itself, rather than using external spreadsheet based applications. A

combination of these data templates enables fitting of various model

parameters to be performed.

Model Fitting

Limitations

JKSimMet will model fit balanced or experimental data to produce a set of

model parameters. It will not tell the user if these values are in typical ranges

or whether the values are realistic. Such judgements rely on the experience of

the user, or on communications with specialists at JKTech.

1.2 Hardware & Operating System Requirements

Successful operation of JKSimMet requires the following:

Computer

System

Intel Pentium PC (or other fully compatible computer) with all of the

following:

Processor speed 1 Ghz recommended;

512 MB memory minimum – 1 GB recommended;

CD-ROM Drive;

2 GB or larger fixed disk drive (with 100 MB free space);

A SVGA or fully compatible equivalent graphics controller

(minimum) – Recommended an XGA graphics controller;

A suitable monitor - 15 inch minimum, 17 or 22 inch recommended.

Printer An MS Windows 7, Vista or XP compatible printer.

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Version 6.0.1 - March 2014Hardware & Operating System Requirements


Operating

System

MS Windows 7, Vista or XP

Keyboard Standard keyboard.

Pointing Device Microsoft Mouse or functional equivalent.

Equipment

Tested

A wide range of equipment combinations have been successfully tested, but if

in doubt JKTech will be pleased to comment on a particular combination.

1.3 Cautionary Tales

Backup

JKSimMet

Installer

It is recommended that a backup copy of the files be made to CD. If the

JKSimMet CD-ROM is damaged, a new CD-ROM can be acquired from JKTech

by notifying them and quoting the version number of the copy of JKSimMet.

Learn by

Example

JKSimMet is a program that is rich in capabilities and easy to operate. The

simplest way to become familiar with the techniques of using JKSimMet and

its capabilities is to follow a structured example. Such an example is provided

with the package. This example assumes no experience with JKSimFloat and

leads the user through a session exploring flowsheet creation, data input and

the use of the simulation features of the program.

It is recommended that some time be spent working through the example

provided (starting with the topic Building a New Project ), until the user is

confident that JKSimMet can be applied to different problems. More detailed

reference information on all aspects of the program is outlined under the

section Using JKSimMet .

Backup Work Remember to save the work to the hard disk regularly, for example as each

section of data (say a flowsheet or a data set) is entered. Usually earlier

versions will be overwritten. If this is done regularly, then when (not if), there

is a power failure or other mishap, the work up to the last save will be on the

hard disk; it will not have been irretrievably lost. There is an auto save

function incorporated in the program that runs every 3 minutes, however

regular manual saving is also recommended.

1.4 JKSimMet Structure

Program

Structure

JKSimMet consists of the following software modules:

Main Program;

Supporting DLL’s;

Program Database;

Project Databases.

1.5 Available Models

The unit models currently available for simulation include the following:

Available

Models

Feeder

Stockpile

Bin

Single deck screen

Double deck screen

Autogenous mill

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Version 6.0.1 - March 2014 Available Models

Overview 19

Pump sump

Sump

Splitters (2 way & 3

way)

Gyratory crusher

Two rolls crusher

Jaw crusher

HPGR crusher

Degradation model

Semi-autogenous mill

Rod mill

Ball mill

DSM Screen

Hydrocyclone

Spiral classifier

Rake classifier

Thickener

Custom Models JKTech can be contacted to add other models to JKSimMet.

1.6 JKSimMet Support

Documentation Three levels of documentation are supplied:

User manual.

Help files.

Model instructions (these are included as the final section in both the

manual and the help files)

Courses JKTech offers regular courses in simulation technology at various locations

around the world. Contact JKTech for details.

Extended

Support

Continuing support is provided by JKTech either through a Maintenance

Agreement, telephone or facsimile contact, or through visits by JKTech to your

site.

E-mail Help JKSimMet project files can be sent electronically to JKTech via the Internet for

assistance. Send files to [email protected].

Updates Updates and bug fixes will be supplied for one year from date of installation/

supply and are available under a maintenance agreement thereafter.

Restrictions A standard licence for the use of JKSimMet permits operation of the software

on a single workstation only. Extension of the licence for additional

workstations at a single site is available for a fee.

Distribution of copies of JKSimMet to other company sites is not permitted.

Additional copies for other sites are available at reduced cost.

Hardware Key

(Dongle)

JKSimMet will not operate without a hardware key (also called a dongle). The

standard key is suitable for a USB port. One working key and one spare key

are supplied with each software licence.

Part

II


Changes from Version 5 21

2 Changes from Version 5

JKSimMet V6 is based on the JKSimFloat architecture and so presents a new

experience and new features to the user, while retaining the underlying

JKSimMet V5 functionality.

2.1 Summary of Main Changes

Main Changes In summary the main differences between version 5 and version 6 are:

Definition of Sieve Series of up to 40 sizes and Survey Data entry

Flexible flowsheet drawer

Configurable Stream Overview including data entry

Simulation Manager for running simulations in batch mode

User editable Info Blocks

Size x Assay mass balancing

2.2 Precautionary Notes on Main Changes

Overview JKSimMet Version 6.0 represents a major shift in many respects from version

5. Version 6 is available free of charge to clients who hold maintenance

agreements and will be available to other users for an upgrade fee.

The most significant change is that JKSimMet has been moved from the old

Visual Basic/Fortran platform to the more modern C++ platform that is used

by JKSimFloat. Thus, the look and feel of JKSimMet V6.0 is now quite different

from older versions and is much more like JKSimFloat. This section of the help

file has been adapted from two stand-alone documents that were prepared to

guide users through their early use of the new version.

Increase from 30

to 40 Size

Fractions

Until now, the maximum number of size fractions available was 30. This

limited the range of equipment that could be handled in a single flowsheet.

The range available in a series was from 2.0 m to 0.086 mm. With the extra

size fractions, that range is now increased to 2.0 m to 0.003 mm or 10 m to

0.014 mm. It is now possible to use as many as 40 size fractions in the

internal series.

Single Master

Sieve Series

Previous versions of JKSimMet allowed the user to specify different size

distributions for each stream in the flowsheet. Internally, these were all

converted to the same series but this was not easily visible to the user. This

flexibility caused problems in mass balancing, where the same sieve series is

required for all streams and for reporting. These problems have been overcome

by using a single master series for all streams in a flowsheet. The user is first

allowed to specify the master series for the project. Once this is done, survey

sizing data obtained using any other sets of sieves can be entered and the

program will then automatically convert such data into equivalent data for

the master sieve series.

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31

36

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Version 6.0.1 - March 2014Precautionary Notes on Main Changes


Small

Differences in

Simulation and

Fitting Results

The two changes discussed above, 40 Size Fractions and the Master Sieve

Series may mean that simulation and model fitting could give slightly

different results in V6.0 compared with V5.3. Our testing has shown that

these differences are insignificant except for the HPGR model – see next

section.

HPGR Model The internal structure of the HPGR model means that the change from 30 to 40

internal size fractions makes significant differences to the simulation results.

Therefore, it is necessary to refit the HPGR model in V6 before conducting any

simulations.

Conversion of

Files from V5 to

V6

V6.0 allows JKSM5 extension files to be opened and converted to JKSMX files.

The conversion process creates a new file and leaves the old file untouched.

The flowsheets created by the conversion process may require some work to

improve them aesthetically. Extensive testing has shown that the converted

files respond correctly throughout the full range of functions, when used in

V6. However, there is always the possibility of issues that have escaped

detection during testing, so please don’t hesitate to contact JKTech if you find

any items that you are concerned about.

Keep in mind that after any conversion process, it is always important to

check the results carefully.

Note that the conversion process does NOT convert component data. This will

be implemented in the next release.

Also, it is not possible to convert .JKSMX files back to .JKSM5 format.

Mass Balancing Apart from the look and feel, one of the major changes is to the mass balance

system. The old JKMBal system previously used could handle only one

dimensional data – size distributions or assays. The new JKMultiBal system,

taken from JKSimFloat, is completely new for JKSimMet and uses different

algorithms that can handle size by assay data. However, because the

algorithms are different, the results may be different. If the data are good

quality and require little adjustment, the results of balancing in the two

versions will be close. However, if the data are of lower quality, the results

from the two versions may well be different. There is no “right” answer in

mass balancing and the results will be heavily influenced by the user’s choice

of starting estimates and standard deviations. Please note that in JKSimMet

V6.0, a zero value for standard deviation is not permitted. When converting

from V5 files, all 0.0 SD values will be converted to “missing”.

Installation Installation of JKSimMet V6.0 will uninstall any older JKSimMet versions.

After installation of V6.0, double clicking on a .JKSM5 file will open V6.0 and

instigate the conversion process.

Contacting

JKTech

Please feel free to contact JKTech if you have any questions or problems with

JKSimMet V6.0. The best contact is via [email protected].

2.3 Toolbar Changes

Main Toolbar A screen grab of the main tool bar is shown below, with annotation to show

the names of the buttons. These names are indicative of their functions and

are in fact the same as the tool-tips that will appear when you hover the

mouse over these buttons.

Note that tool-tips for the buttons will be switched on by default when you

mailto:[email protected]

Version 6.0.1 - March 2014 Toolbar Changes


first open the program. They can be switched off if required. This is done by

selecting Tools from the main menu, then Customize. For further details on

this, see the Tools Menu topic .

Side Bar As indicated in the annotations to the screen grab above, the three buttons for

entering the main areas of JKSimMet functionality (viz. Balancing, Fitting and

Simulation), were moved after this screen shot was taken. They have now

been transformed into large buttons in a separate toolbar located in the left

panel, just above the flowsheet list. An annotated screen shot of this toolbar is

shown below.

Note that many of the screen shots in this help file were taken before this

change in the toolbar structure took place. These shots have generally not

been updated where the difference was considered irrelevant to the user's

understanding of the topic.

Flowsheet

Toolbar

The new version of the flowsheet tool-bar is shown below, again annotated to

indicate the names of the buttons.

2.4 Creating Projects

After opening JKSimMet V6 the user may create a new V6 project, open an existing

V6 project or open an existing V5 project from the file menu.

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Version 6.0.1 - March 2014Creating Projects


Selecting “New Project” will open a window in which the user may enter the file

name for the new project and save it (a default file name is supplied).

If the user chooses “Open Project” they will be presented with a window giving

them the option to open either a V5 or V6 project:

Version 6.0.1 - March 2014 Creating Projects


If the user chooses to open a V5 file they will be presented with this prompt:



Clicking “Save” will initiate the import process. Note that the process of

converting the V5 file to V6 leaves the V5 file unchanged, it creates a new V6 file

and transfers the flowsheet and data into the new file.

If the V6 file name already exists the user is asked if they wish to overwrite the

existing file. Choosing no will return them to the save prompt screen to enter or

choose another file name.

On return the user will be asked if they wish to use V5 style flowsheet icons:

After clicking “save” the user will be presented with a window to choose or

modify the sieve series to be used as the initial “Master” series:

Version 6.0.1 - March 2014 Creating Projects


The user is presented with all unique sieve series defined in the V5 flowsheet to

choose from. The default master series is copied from the feed in the V5 project

with material in the coarsest size fraction. The user may modify this series as they

choose. Clicking OK will generate the project and the user is advised that they

may need to re-run simulation:

If the user creates a new project they will be presented with a blank flowsheet:



If they open a V5 or V6 project the first flowsheet in the project will be opened:

2.5 Sieve Series and Survey Data Entry

Master Sieve

Series

A fundamental difference between JKSimMet V5 and V6 is the introduction of the

concept of a “Master” sieve series. In V5 the user could define individual sieve

series for each port for entry of experimental data and viewing of simulated,

fitted and balanced results. In V6 the user defines as many sieve series for

survey data entry as they need, and a single “Master” series for the entire circuit

to view and edit data thereafter. The user may define up to 40 sizes in each sieve

series in V6, compared with 30 sizes in V5.

Version 6.0.1 - March 2014 Sieve Series and Survey Data Entry


The sieve series definition window may be opened from the FlowSheet menu or

the toolbar:

The user clicks the “Insert” button ( ) to insert a new sieve series. They may

then name it appropriately for the part of the circuit the sieve series relates to.

After this they enter the relevant sieve series, either directly, via copy and paste,

or entering a new top size and generating a new root 2 series by clicking the

“Root 2” button ( ). The new series will then be available for selection against

appropriate streams in the “Stream” section.

Version 6.0.1 - March 2014Sieve Series and Survey Data Entry


After creating and allocating sieve series against appropriate streams, the user

may open the Survey Data window and enter their experimental data obtained

through plant surveys.

The user may choose to view the streams for the whole circuit (“All Sieves”) or

for specific parts of the circuit as defined by the specific sieve series selected.

They may then choose to view the stream data as any of the defined sieve series

(“View As”), but will only be able to edit the data for the streams that have been

assigned that sieve series. In addition they may view the data as % Retained,

Cum % Retained or Cum % Passing, and choose the interpolation method for

translating the survey data into the global Master sieve series.

If the user wishes to create extra sieve series they may click the “Edit Sieve

Series” button to load the Sieve Series Overview, make their changes then return

to the Survey Data window and re-make their selections. After entering the

survey data and choosing the appropriate interpolation method, the user may

click the “Transfer” button to translate the survey data into the Master series for

all streams. They will be prompted to confirm the action before proceeding as

existing data will be overwritten:

The survey data is stored so the user may later modify and re-translate the data

into the master series.

Version 6.0.1 - March 2014 The New Flowsheet Drawer


2.6 The New Flowsheet Drawer

The new flowsheet drawer works in two modes – locked and unlocked. When

the flowsheet is locked adding and removing icons, pasting items, moving items

etc is not possible, but access to the equipment models and stream data

windows is enabled by double clicking the appropriate icon or stream. When

the flowsheet is unlocked the user may create and modify the flowsheet by

selecting equipment icons from the tree view to the left of the flowsheet and drag

and drop them directly on to the flowsheet, then connect them by clicking and

dragging between ports. The new flowsheet drawer is more flexible than the V5

Version, including the ability to route streams exactly as the user wishes, and

have complete control over the placement of icons and setting of display

features (colour, size etc). There is also an automatic labelling feature for units

and streams.

By default the flowsheet drawer works with vector graphic based icons, unlike

the bitmap icons used in V5. However at the point where a new project is being

created, the user may choose to have it use the bitmap icons (V5 style)

throughout all its flowsheets. Note however that once this initial selection has

been made, you will not be able to switch icon styles for the project in question.

For further information on use of the flowsheet drawer, refer to the section

Building and Manipulating a Flowsheet .

2.7 System Properties

The System Properties in V6 serve 2 purposes – as a place to set properties that

are global to the project, and to define the elements (“components” in V5) that

may be used in mass balancing. System Properties are accessed from the

Flowsheet Menu or the toolbar:

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Version 6.0.1 - March 2014System Properties


The first selection in the System Properties is the Elements. The user defines the

Elements and display units (% or g/t) used in mass balancing:

The bulk Solids and Liquid SG used in simulation and the default global size

markers used in each stream window are defined in the Miscellaneous System

Property.

Version 6.0.1 - March 2014 Accessing Models


2.8 Accessing Models

In V5 double clicking an icon takes you straight to the selected model

window. In V6 when the user double clicks on an equipment unit they are

first presented with a window that allows them to change model selection for

the unit or open the feed or product stream windows for that unit.

When the user clicks on the arrows next to the model selection they are taken

into the model window, with a display very similar to V5 and identical

parameters.

Version 6.0.1 - March 2014Equipment Manager


2.9 Equipment Manager

In addition to individual model viewing/data entry, V6 provides the

Configurable Equipment Manager that allows the user to construct summary

views for all equipment using a selected model.

This allows flexibility in choosing which parameters to view/edit for a selected

model. To access the Equipment Manager choose from the Flowsheet menu or

the toolbar:

The user may construct an Equipment Overview for each model used in the

circuit, insert columns and define the parameters to be displayed by clicking in

the top cell of the column.

This will invoke the selection box from which they select the parameter for

display, after which they can then view or edit data for this parameter. In

addition the Overview tables can be printed, copied to the clipboard, or

exported to Excel.

For further information on this subject can be found in the topic Configurable

Equipment Manager .153

Version 6.0.1 - March 2014 Viewing and Entry of Stream Data


2.10 Viewing and Entry of Stream Data

JKSimMet V6 replaces the concept of “ports” with “streams”. In JKSimMet V6 the

user enters and views stream data by double clicking directly on streams, unlike

V5 where they right click on a unit and choose the port. This displays a familiar

window showing Totals and Sizing data:

The user may choose which data types they view in the columns for all streams by

clicking the Data Type View button.

An additional feature is the SD Calculator, which allows the user to make bulk

changes to SDs for a given stream or multiple streams, and for a single data point

or multiple data points.

Version 6.0.1 - March 2014Viewing and Entry of Stream Data


Some further information on the SD Calculator is contained in the topic Viewing

Individual Stream Data .

2.11 Configurable Stream Overview

Like V5, JKSimMet V6 provides an Overview window to view summary stream/

port data. Unlike V5, the V6 Overview provides complete flexibility in selection

of data to view, and where the data is user editable (e.g. experimental) it can be

modified in this window. To access the Configurable Stream Overview choose

from the Flowsheet menu or the toolbar:

The user may construct as many Stream Overviews as required, but is provided

with several defaults displaying various data. The user may insert columns and

define the data to be displayed by clicking in the top cell of the column. This will

invoke the selection box from which they make their selection, after which they

can then view or edit the data. In addition the Overview tables can be printed,

copied to the clipboard, or exported to Excel.

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Version 6.0.1 - March 2014 Configurable Stream Overview


For further information refer to the topic Configurable Stream Overview Window

.

2.12 Simulation Changes

The V6 simulation window may be accessed from the Flowsheet menu or the

toolbar:

The V6 Simulation window largely replicates the functionality V5 implements

in three tabs:

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Version 6.0.1 - March 2014Simulation Changes


V6 has intuitive equipment and stream selection via the check boxes or by

clicking on equipment and streams in the flowsheet, and has the ability to create

multiple select lists which like V5 are available in model fitting. For further

information on Simulation refer to the manual or help files.

2.13 Simulation Manager

The Simulation Manager allows users to run a batch of simulations to observe

the effect of adjusting unit operating parameters in each simulation. The

simulation manager may be accessed from either the FlowSheet menu or the

toolbar:

The method for selecting parameters and calculated results to view is identical

to the Equipment Manager. The user may specify absolute or % change to the

original data values for each simulation.

Version 6.0.1 - March 2014 Simulation Manager


For further information on the Simulation Manager refer to the topic Working

with the Simulation Manager .

2.14 Changes to Reporting

The reporting function in V6 is similar to V5, but there is no report preview or

ability to print reports directly from the program. Instead the report is exported

directly to Microsoft Excel and opened for viewing or printing. Reporting may

be accessed from either the FlowSheet menu or the toolbar:

In addition, to avoid the need to modify existing reporting templates when

model selections change, each unit’s data occupies a fixed maximum number of

rows in the Excel worksheet.

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Version 6.0.1 - March 2014Changes to Reporting


For further information on the Reporting refer to the topic Using the Reporting

Feature .

2.15 Changes to Graphing

The Configurable graphing function in V6 is similar to V5, but the selection and

graph display are contained in one tabbed window and there is no ability to

print graphs directly from the program. Instead they may be copied to the

clipboard and pasted to other applications for viewing and printing. The

Graphing may be accessed from either the FlowSheet menu or the toolbar:

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Version 6.0.1 - March 2014 Changes to Graphing


The streams or equipment to display graphs for are selected in the top row. The

graph format options can be set by clicking the “Format” button. After all

options are set, the user selects the Graph tab to view the generated graph:

The user may also change the format options in this tab, and copy the graph to

clipboard for use in other applications.

For further information on the Graphing refer to the topics Plotting the Size

Data Graphs in the Mass Balancing section and Presentation of Model

Fitting Results in the Model Fitting section..

2.16 Changes to Info Blocks

The Flowsheet Info Blocks function in V6 is an enhanced version of V5. Users

may choose any equipment or stream parameters/data to view in the Info Blocks,

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Version 6.0.1 - March 2014Changes to Info Blocks


and where the data is user editable (e.g. experimental) it can be modified in the

Info Blocks. The Info Blocks may be accessed from either the Flowsheet menu or

the toolbar:

The user selects the number of parameters then clicks on each cell to define the

parameter or data to be displayed:

Version 6.0.1 - March 2014 Changes to Info Blocks


The user then selects the streams or equipment to apply the info blocks to and

clicks “Add Info Block”. For further information on the Info Blocks refer to the

Information Blocks topic in the section Using JKSimMet .

2.17 Model Fitting Changes

The Model Fitting Window in V6 consolidates the five tabs in the V5 window, but

provides the same functionality. Unlike V5, the parameters available for fitting are

not defined through the jkp database; rather the selection is made within the

Model Fit window. The Model Fitting may be accessed from either the Flowsheet

menu or the toolbar:

Each model fit case is represented by a user defined circuit selection. Unlike V5,

each model fit case in V6 is associated with unique parameter selection lists –

they are not shared between model fit cases. Also it is not possible to fit model

parameters for equipment that is not in the selected circuit for the fit case.

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Version 6.0.1 - March 2014Model Fitting Changes


Master/Slave fitting of multiple data sets is controlled from this window. For

further information on model fitting refer to the Model Fitting section.

2.18 Mass Balancing Changes

The Mass Balance window in V6 is quite different from V5 but provides

essentially the same functionality, including the ability to balance flows, sizes

and assays across the whole circuit or selected parts of the circuit. The Mass

Balance window may be accessed from either the Flowsheet menu or the toolbar:

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Version 6.0.1 - March 2014 Mass Balancing Changes


In addition, V6 provides the ability to balance assays within size classes as well

as total assays and sizes. Unlike V5, the user does not balance everything at

once. The suggested process to balance a whole circuit:

1. Make selections for all required equipment, streams, sizes and elements.

2. Set TPH Solids and Sizes to Adjust and all other components to unused,

then run the balance.

3. Then set the TPH Solids and Sizes to Fixed, the TPH Water to Adjust and

% Solids to Influence and run the balance again.

4. Set the TPH Water back to unused and the Elements to Adjust and run

the balance again.

5. Set the Elements to Fixed and Size x Element to Adjust and run the

balance a final time.

For further information on mass balancing go to the Mass Balancing section.230

Part

III


Installing JKSimMet 47

3 Installing JKSimMet

Installing

JKSimMet

This chapter provides installation instructions for JKSimMet V6.

3.1 Contents of the Package

Package

Contents

The JKSimMet system comes either as a package containing two “HASP” keys

or dongles and as a download from the JKTech website. This manual is also

available as a download.

Paper copies of the manual and the JKSimMet pdf file are on CD and can be

supplied on special request.

The manual (and help files) contain information on the installation and

maintenance of the JKSimMet software, a tutorial guide for first-time users and

a comprehensive reference chapter (Using JKSimMet ).

3.2 JKSimMet Installation

Hardware /

Software

Requirements

To be certain of a successful installation and of a system that works efficiently

once installed, you should check that your physical system and operating

system comply with the requirements outlined under the heading Hardware

and Operating System Requirements .

User Privilege

Required

As JKSimMet requires several device drivers the user must have full

administrator privileges to install or uninstall JKSimMet.

JKSimMet V6

Installation

JKSimMet V6 is a standard Windows program. The steps required to install the

program are as follows:

Step 1 If you have an earlier version of JKSimMet on your computer, make a

backup copy of any existing projects

Step 2 If you have JKSimMet V5 installed already on your computer, go to:

Control Panel

Select Add/Remove, and

Select JKSimMet V5

Uninstall

Step 3 Ensure that the hard lock key is installed in a USB port in the

computer as this interferes with the installation of the hard lock

drivers. If you have downloaded the program from the JKTech web

site, double click on the appropriate .exe file. This file will have a

name that is unique for your installation. It may be located in a

Downloads directory or wherever else you may have elected to store

it on your hard drive following the download.

Step 4 If your copy of JKSimMet V6 is on a CD-ROM, insert the disk into

your CD drive. The install program should auto start, alternatively

double click on the installation .exe file. This launches the

InstallShield Wizard. Follow the instructions on the screen. The

install program will guide you through the setup process. If you are

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Version 6.0.1 - March 2014JKSimMet Installation


installing from a CD and it does not auto start, go to the Windows

Start Menu, select RUN and then Browse to find the appropriate .exe

on your CD Drive.

Step 5 The default location for the installation of JKSimMet is:

<C:\Program Files(x86)\JKTECH\JKSimMet 6.0> for 32 bit

computers

<C:\Program Files\JKTECH\JKSimMet 6.0> for 64 bit computers

Click on the "Change" button if you wish to install the program in a

different location (see below).

Step 6 Once the installation is complete, you must then plug your

protection key (dongle) into one of the USB ports of your computer or

the parallel printer port (as appropriate), in order to allow operation

of the program. Note that the protection key(s) provided with your

copy of V5.0 or V5.1 will also work with V6.

Note: The install program may also ask to update your HTML help file viewer.

This will allow full use of JKSimMet V6 help.

If the default

path is not

chosen for

installation

If the default path is not the desired installation location, click on the Change…

button in the InstallShield Wizard and follow the instructions to select a new

location.

Non-English

Versions of

Windows

If a non-English version of windows is installed, the spelling of the install path

may be different. If this is the case, you must modify the install path to the

correct spelling using the Change… button.

Installing

Additional

Shortcuts

As part of the installation process, a shortcut to the program will be placed on

your desktop. In Windows 7 you can also pin a shortcut to your Start Menu or

to your Taskbar at the bottom of the screen. Left-click on the Start button at the

bottom left of the screen, then on Program Files and then on the JKSimMet V6

Version 6.0.1 - March 2014 JKSimMet Installation

Installing JKSimMet 49

folder within the Program File sub-menu. Now right-click on the item JKSimMet

V6. When the right-click menu appears it will look similar to the illustration

below.

Making an

accessible

Shortcut

From here you can select to either Pin to Start Menu or Pin to Taskbar. You may

find one of these shortcuts is more convenient, especially if you are going to be

using the program regularly.

Part

IV


Learning JKSimMet 51

4 Learning JKSimMet

Learning

JKSimMet

This section (Learning JKSimMet) is designed primarily as a tutorial exercise.

It is anticipated that the first time user of JKSimMet might spend two to three

hours working through this section step by step. In this way the new user

should gain sufficient confidence and knowledge to begin using the system in

earnest.

The first main heading is JKSimMet Basics. This chapter contains a general

description of the procedure for building a simulation model. It also contains

a list of all the available equipment items and the process models

associated with each of them. This is followed by some basic instruction on

operating the software under the topics Mouse and Cursor and JKSimMet

Display . The topics that follow then take the user step-by-step through

the procedure for creating a new project in order to build a simulation model

for a flowsheet. Techniques that apply for the manipulation of an existing

project are covered in this section under the main heading Working with an

Existing Project .

Given the nature and design of JKSimMet, the user will very quickly be able to

learn the basic operating techniques. It is assumed that the user already

understands the techniques of mineral processing simulation and also has

some appreciation of the standard features of the MS Windows 7, XP/

NT/2000 interface.

Typical Users of

JKSimMet

JKSimMet is a general purpose computer software package for the simulation

of comminution plant operations. The package is designed to service the

diverse needs of:

Plant and Development Metallurgists - to apply modern process

analysis techniques to characterize plant behaviour.

Plant Operators - to understand the effect of day to day changes in

circuit operation on metallurgical performance.

Researchers and Academics - to test and evaluate new process

models.

Consultants - to develop and demonstrate process optimization and

design for client operations.

Once familiar with the program, you will be able to use the JKSimMet

simulation engine to determine the metallurgical performance of your

processing circuit under various operating condition scenarios. The ability to

do this is facilitated by the fully interactive nature of the program and it's

flowsheet based graphical interface.

4.1 JKSimMet Basics

Some JKSimMet

Basics

Before you can begin to build a new project, you need to get familiar with the

basic concepts covered in this chapter.

4.1.1 JKSimMet Data Structure

The data structure within JKSimMet V6.0.1 consists of the following:

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Project A project is the container in which the user stores all of the data related to a

particular body of work. The project contains one or more flowsheets and the

associated equipment and stream data.

Flowsheet A flowsheet is a graphical representation of a complete processing plant or a

Section of the plant and consists of an appropriately configured collection of

process units and streams. The flowsheet can have (and usually will have),

internal recirculating streams.

Equipment Each process unit in the flowsheet is represented by an Equipment Unit.

JKSimMet allows the user to select the equipment from a list of processing

plant equipment types and to display their pictorial representations (icons) on

the screen. This equipment is identified within the system by a name that the

user can specify.

The orientation of the equipment and the position of the equipment on the

flowsheet diagram can also be specified. There are a number of choices for the

process models to be used for each equipment unit.

Streams A stream is a description of the flow of material between process units. This

description includes the sizing characteristics, the SG and the water content

of the stream. It contains sufficient information to perform simulations via the

various models that are currently in use and there is virtually unlimited

capacity for developing and testing new models in the future.

The stream connection between two equipment units is made by drawing a

line that connects the appropriate feed and product ends of the equipment

units in question. On simulation, JKSimMet automatically checks to ensure

that all stream connections are valid. The streams are identified within the

system by names that the user can specify.

4.1.2 Available Equipment Items and Associated Models

Equipment Items Below is a listing of the JKSimMet equipment items, showing the associated

menu icon and the process models available for each of them.

Equipment

Category

Equipment

Item

Menu

Icon

Available Models (Model ID)

Stream

Source

Feed (Solids

Feeder)

Terminator - Solids Feeder (1300)

Water Feeder Water Feeder - Required % Solids

(1251)

Water Feeder - Water Addition (1252)

Crushers Jaw Crusher Crusher - Anderson/Whiten (400)

Crusher - Anderson/Whiten - Size

Extended (405)

Size Converter (490)

Gyratory

Crusher

Crusher - Anderson/Whiten (400)


Extended (405)

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Cone Crusher Crusher - Anderson/Whiten (400)


Extended (405)


Rolls Crusher Crusher - Anderson/Whiten (400)


Extended (405)


VSI Crusher Crusher - Anderson/Whiten (400)


Extended (405)

Size Degradation (480)


HPGR High Pressure Grinding Rolls (402)

Degradation Size Degradation (480)


Mills Autogenous

Mill

Perfect Mixing Ball Mill (420)

Semi-Autogenous Mill - Leung (430)

Semi-Autogenous Mill - Sim/Org

Scaling (435)


Rod Mill Rod Mill - Lynch/Kavetsky (410)


Ball Mill Perfect Mixing Ball Mill (420)


Screens Trommel Splined Efficiency Curve (203)

Simple Efficiency Curve (210)

Efficiency Curve - Water & Fines

(211)

2-Way Simple Splitter (810)

Single Deck

Screen

Splined Efficiency Curve (203)



(211)

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Single Deck Screen - Kavetsky (230)


Double Deck

Screen (One

Under

Product)

Double Deck Screen Based on

Efficiency Curve (215)

Double Deck Screen - Kavetsky (235)

DSM Screen Splined Efficiency Curve (203)



(211)

Efficiency Curve - Variable d50c (251)


Water & Solids 2-Way Splitter (813)

// wrong

Classifiers Air Classifier Splined Efficiency Curve (203)


Hydrocyclone Nagaswararao Cyclone (200)

Nagaswararao Fines (201)




(211)



// wrong

Narasimha-Mainza (221)

Spiral

Classifier




(211)



//wrong

Rake Classifier Splined Efficiency Curve (203)



(211)

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// wrong

O-Sepa

Classifier



Splitters 2 Product

Splitter


Fixed 2-Way Volume Splitter (812)


// wrong

3 Product

Splitter


Storage/

Transport

Bin Size Degradation (480)


Simple Combiner (800)

Pump Size Converter (490)


Pump Sump Size Converter (490)


Sump Size Converter (490)


Stockpile Size Degradation (480)



Thickener Simple Efficiency Curve (210)


(211)

Filter Model Controlled by % Solids

to U/F (240)

Final Product Terminator (1300)

Separators Flotation Cell Splined Efficiency Curve (203)


Efficiency Curve - Flotation (212)

Efficiency Curve - Water & Fines -

Flotation (213)



//wrong

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Flotation

Column




Efficiency Curve - Water & Fines -

Flotation (213)



//wrong

Spiral

Separator




(211)



//wrong

2 Product

Separator




(211)




//wrong

3 Product

Separator


4.1.3 Building a Simulation Model

What is

Simulation

Simulation is based on the ability to build a model that represents a real

system. The behavior and characteristics of the model must be similar to those

of the real system. JKSimMet allows the user to draw the flowsheet of a

comminution circuit, input and manipulate the data for a very wide range of

operating conditions and see the predicted results of running the circuit.

Steps to Building

a Simulation

Model

The user of JKSimMet proceeds through a series of tasks as outlined below.

1. Building a flowsheet diagram of the comminution plant on the

computer screen.

2. Input the feed stream data in the Feeder equipment.

3. Select the models for the equipment and input the required model

data.

4. Run the Simulation of the flowsheet.

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5. Review the results of the simulation in the Report window or in the

individual stream data windows.

These tasks are described in more detail under the heading Building a New

Project , which takes the user through each step.

Once a simulation model of a circuit has been built, the metallurgist can use

JKSimMet to assess the impact of altering various plant conditions on

metallurgical performance, until a satisfactory design or an optimum

operating condition for an existing plant is achieved. The results from

JKSimMet can be exported to Excel for printing, graphing and further

analysis. Data can also be transferred to other programs (such as MS Word),

by copying them to the clipboard and pasting into the other program.

Values calculated in a simulation include:

flow rates of solids and water;

pulp densities (percentage solids);

particle size distributions (if size has been chosen as one of the stream

properties);

Solids and water recoveries.

4.1.4 The Mouse and Cursor

The Mouse The standard two button mouse is used as the pointing device in JKSimMet.

This manual refers to ‘left click’ and ‘right click’, which simply means to press

the left or right hand button on the mouse. Note that if the words ‘left or ‘right’

are omitted, the default is always ‘left click’.

The manual assumes that the user is familiar with common mouse techniques

such as double clicking and click-and-drag.

Note that when you follow a link (underlined blue italics) which takes you to

another topic and you then wish to return to the original topic, clicking the

back button on your mouse will achieve this. That is of course assuming you

have a mouse that is equipped with forward and back buttons.

The Cursor The cursor is the visual feedback to the user of the current mouse position on

screen. Any click of a mouse button will interact with the image located at that

position. In JKSimMet V6.0.1 the usual form of the cursor is an arrowhead.

When the cursor is over equipment in the flowsheet window and the

flowsheet is unlocked, the cursor will change to show arrows pointing in 4

directions to indicate that the equipment item can now be moved. To achieve

this you can now just hold down the left mouse button and drag the item.

Releasing the mouse button will drop the item into its new location.

Once the left mouse button has been clicked while hovering over an

equipment unit, you will see that the item then has 8 grey squares around its

periphery to indicate it is now selected. If you then double click on the item,

you will bring up the equipment properties dialog box where the attributes of

this equipment can be modified. Alternatively you can right click and select

Properties from the right-click menu.

Cursor

Movement

When working with a flowsheet in JKSimMet, the mouse provides the means

of moving the cursor around the screen and selecting individual streams or

equipment items as required. In the equipment, stream and model data

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windows, the cursor control keys (also known as the arrow keys) may be used

to move the cursor from one data cell to the next. In this case, the movement

will be in the direction of the arrow key used. Otherwise you can still use the

mouse to hover over and click to select, any required data entry cell.

To begin entering data into one of the cells, you can just begin typing once the

cell has been selected. To edit data already existing in a cell, you must first

double-click with the mouse to select the text within that cell. The text in the

cell will then be highlighted with white figures on a blue background. Starting

to type at this point will again just over-type the existing text. If your intention

is to edit the existing text, you need to now single click in the highlighted cell.

You will then see the mouse cursor flashing as a vertical line between the

characters and you can move it to the left or right via the arrow keys.

In summary then, to overwrite existing text, just begin typing once the cell has

been selected. To edit existing text, double-click and then single-click inside

the target cell.

Appearance As with all MS Windows programs, the preferences that the user sets for the

Windows desktop will provide colours and fonts for many of the tools and

menus within JKSimMet.

Keyboard Access Most of the functionality of JKSimMet can also be accessed from the keyboard

using standard MS Windows conventions.

4.1.5 The JKSimMet Windows

The JKSimMet V6.0.1 display uses windows to present the various types of

data on the JKSimMet desktop. These windows include the following:

flowsheet window

equipment and port data windows

graph windows

data overview window

the report window

Users may have as many windows open on the screen as they wish at any

one time. An XGA video card and a large monitor are recommended to

gain full advantage of this capability.

Many of the windows are divided into several distinct areas that are

accessed by selectable tabs. Each area is used to convey specific types of

information.

Note that most windows may be minimized for convenience. However,

some non-critical changes (eg. an equipment name change) may require

that a window be closed before other windows are updated.

4.2 Building a New Project

Building a

Project

Having gained an understanding of what JKSimMet does and generally how

it works, this section will take you through a series of steps in order to build a

JKSimMet project. A simple flowsheet will be used for learning purposes. In

order to cover as many of the available techniques as possible though, this

tutorial will take a number of diversions along the way during the process of

Version 6.0.1 - March 2014 Building a New Project


putting together this simple flowsheet.

In this demonstration we will be assuming that you already have the

necessary parameters for the main equipment items on this flowsheet. Later

on in this help file, you will be shown how to carry out the fitting process in

order to obtains such parameters and also how to perform mass balancing

which is normally performed ahead of any fitting exercise.

4.2.1 The Steps to Simulation

This section contains a step by step tutorial style set of instructions that is

tailored for users who are still becoming familiar with the program. The

following section on Using JKSimMet covers all of the basic operational

features of JKSimMet and is structured as a reference section.

Steps to

Simulation

The stages involved in performing a simulation are outlined below, and the

sections JKSimMet Start Up through to Viewing Individual Stream Data

are designed to guide the user through each stage.

Step 1 Make a backup copy of any existing projects

Step 2 Startup JKSimMet - covered in the topic Start JKSimMet

Step 3 Create the flowsheet – covered in sections Create a New Project

through to Build a New Flowsheet - Add Streams . Note that a

flowsheet must have a Feed equipment unit and all equipment

items (apart from feeders) must have feed streams to be valid.

Step 4 Set the System Properties in the section Flowsheet Data - System

Properties . These are global characteristics that do not change

during simulation. In JKSimMet they consist of only the solids and

the liquid SG values and assays where needed for mass balancing.

Step 5 Input feed stream data into the Feeder equipment item - see section

Flowsheet Data - Feeder Equipment .

Step 6 Select the models for the equipment and input the required model

data – section Flowsheet Data - Equipment & Models . The data

for the models will usually be derived from plant or test work data.

Some data may also come from previous experience. The user can

review or correct the data at any time after data entry.

Step 7 Run the Simulation of the flowsheet – section Simulation .

Step 8 Review the results of the simulation in the Configurable Stream

Overview – section Viewing Data Using Configurable Stream

Overview .

Step 9 Review the results of the simulation in the individual stream data

windows – section Viewing Individual Stream Data .

Step 10 From the Configurable Stream Overview, the results of the

simulation can be copied to the clipboard and then exported in a

printer-friendly format to other programs such as MS Excel, as

required. After analysis of the results the circuit configuration can

be altered, the capacity and characteristics of the equipment

changed, the properties of the feed stream adjusted and the

simulation process repeated until a satisfactory result is obtained.

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The section Working with an Existing Project outlines how to

work with an existing project in this manner.

4.2.2 JKSimMet Start Up

JKSimMet Start

Up

The instructions for starting JKSimMet V6 are as follows:

Step 1 Plug the JKSimMet protection key into the appropriate place in the

computer.

Step 2 Left click on the Windows Start button at the bottom left hand

corner of the screen to open the Start menu.

Step 3 Move the cursor to select the All Programs sub-menu.

Step 4 Move the cursor to highlight the JKSimMet V6 program from the

list displayed in this sub-menu and left click. You will then see

two items; JKLicenseManager and JKSimMet V6. Left click on the

latter to launch the program. The JKSimMet logo is displayed

while the program is loading.

Step 5 Alternatively, JKSimMet can be started by double clicking on the

JKSimMet icon on your desktop or by clicking on a Taskbar icon in

Windows 7, if you have opted to pin a program shortcut to the

Taskbar.

Having successfully launched the program the main JKSimMet session

window will open as shown below. From here, the next step is typically to

open a previously saved project (see section Working with an Existing Project

), or to enter the data for a new project (see sections Create a New Project

through to Flowsheet Data - Equipment & Models ).

Changing

Window Size

Note that the session window can be re-sized using the minimize and

maximize buttons (top right corner) or by moving the cursor to any edge of the

window. When it is positioned over the border line the cursor will change

from the arrowhead to a line with arrows on each end; left click and drag with

this cursor to change the window size and release the mouse button when the

window size is as required. Note also that the various sections of the session

window can be re-sized in the same manner.

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4.2.3 Creating the New Project

Creating a New

Project

In this exercise a new project will be created by following the steps outlined

below. The project you are about to create will be a simple closed circuit ball

mill flowsheet.

New Project Step 1 After starting JKSimMet click on the New Project icon on the

toolbar or select New Project from the File menu. This will open

the New Project window.

Define Project

Name

Step 2 A dialog box will open where you can select a suitable directory

(probably somewhere within My Documents would be best) and

also enter a name for the project. Note that you can create a new

sub-directory for this tutorial work by clicking on the icon circled

in the screen grab below.

In this case we will replace the name 'New JKSimMet Project' with

‘Learner Project’. After making this change, click on the Save

button.

You will then be presented with the option to either use the more



realistic icon style familiar to Version 5 users, or the stylised icons

that have been adopted as the default for the Version 6 interface.

Note that once you make this selection, you cannot switch back

again within this same project and you cannot mix icon styles

within a project.

Having made your selection, the new project will open. The name

of the project ('Learner Project' in this case) will be displayed in the

title bar of the main window. The new project will have a default

flowsheet called ‘FlowSheet1’, as shown below. It will initially be

empty of any equipment and streams.

Define

Flowsheet Name

Step 3 To change the name of the flowsheet, right click on the flowsheet

name ‘FlowSheet1’ in the left panel and select Properties from the

drop-down menu. Click in the Flowsheet Name text box and type

in the new name; use the name ‘Learner Flowsheet’.



4.2.4 Adding Flowsheet Equipment

Adding

Equipment to

the Flowsheet

In this exercise a flowsheet for a comminution plant will be created using the

graphics-based flowsheet drawing tools in JKSimMet. Check that the flowsheet

is not locked before you begin - the Lock button ( ) should not be depressed.

However, the flowsheet should be unlocked by default, after you have just

created a new project.

Save the

Flowsheet

As with all computer programs, your work should be saved regularly to avoid

loss of data. To save changes to the project, click on the Save Project button or

select Save Project from the File menu.

Select the

Flowsheet from

Left Panel

Step 1 The far left panel contains the list of flowsheets that are contained

in the current project. In this case, there is only one flowsheet. This

is the default flowsheet that was created along with your new

project and has now been re-named as Learner Flowsheet. Note that

the project name and the flowsheet name now appear in the title bar

at the top of the window.

The Learner Flowsheet will be selected by default since there are no others.



The available equipment list is displayed in the centre panel of the session

window. The equipment icons are grouped by equipment functionality,

progressing from the feed end of the plant to the final product. An exception is

that Separators are placed in a group at the end of this list, since they are not so

often required in JKSimMet, this program being primarily a comminution

modelling tool.

To the right of this list is a large blank area where you will be constructing the

new flowsheet.

If your project had more than one flowsheet, to change the flowsheet selection

you would need to double click on the required flowsheet in the left-panel list.

The selected flowsheet's contents would then appear in the right (flowsheet

display) panel.

Create New

Equipment

Units on the

Flowsheet

The new blank flowsheet is now ready for equipment to be added. Note that a

flowsheet MUST have at least one Feed equipment unit, as it is in the Feed

equipment unit that the feed stream data are defined. So we will add this first.

Add Feed

Equipment

Step 2 Double click on the Feeds Folder and then click on the Feed

equipment icon from the equipment list and then place the cursor

over the flowsheet. The arrow cursor will change to the equipment

placement cursor (a cursor with the equipment icon next to it - see

below).

Move the cursor to the position on the flowsheet where you require

the Feed equipment to be placed and click again. You can move it

later, so there is no need to be precise. If you change your mind

about adding an item you have selected before you have placed it

on the flowsheet, just right-click to cancel the placement.

Add the Ball

Mill

Step 3 The Ball Mill equipment item should now be added to the flowsheet

in the same manner as the Feed equipment. To do this, open the

Mills folder and click on the ball mill icon in the equipment list,

move the cursor to the required position on the flowsheet and click

again.



Add the

Ancillary

Equipment

Units

Step 4 You now need to add the auxiliary equipment units - namely a

cyclone plus the sump/pump to feed it. When you have placed

these items, your screen should look something like the one

illustrated below.

Add Water

Feeders to the

Flowsheet

Step 5 You now need to add two Water Feeder units, which should be

added so that their locations are similar to those shown in the

screen grab below.



Exercise:

Adding

Multiple Units

To add multiple units, press Ctrl when selecting an equipment item from the

list. Instances of the selected unit can then be placed by repeatedly left clicking

on the flowsheet. The process can be discontinued by right clicking anywhere

on the flowsheet, or by clicking on the arrowhead (Select) button in the toolbar (

).

Exercise:

Deleting Units

If you have multiple units on a flowsheet, some of which you don't require,

deleting the surplus units is simple. Clicking on an individual unit will select

it and you can select multiple units by holding down the Ctrl key for your

subsequent selections. After one or more units have been selected, you can just

hit the Delete key to remove them. Alternatively, you can select Delete from the

Edit drop-down menu. A dialog box (shown below) will then be displayed,

which asks you to confirm the deletion - the purpose of this being to reduce the

chances of accidental deletion.

Note that if you press the Delete key and nothing happens, it will most likely be

because the flowsheet is currently locked. In this case, click on the Lock button (

) and try again.

Add the Final

Product Icon

Step 6 Lastly we will add a Final Product equipment icon to the flowsheet.

This icon is located under the Storage / Transport heading and is

added in the same manner as any other equipment unit.

The Final Product icon is optional but the stream which feeds it is

essential. This is where the product data are stored.



Copying

Equipment

Units

Multiple units may also be added by placing a single unit on a flowsheet in the

normal manner, then selecting this equipment item by clicking once on it before

copying and pasting to wherever else it is needed on the flowsheet.

There are many alternative ways to achieve the copy and paste operation.

Copying can be done by pressing Ctrl and C or by clicking the Copy button (

) on the toolbar. Alternatively you can select Copy from the Edit menu or

from the right-click menu (with the mouse cursor placed over the equipment

item in question). Multiple units may then be placed on the flowsheet by

performing a paste operation at locations where the extra units are required.

Again this can be achieved in a number of ways; by pressing Ctrl and V, by

clicking the Paste button ( ) on the toolbar or by selecting Paste from the Edit

menu or from the right-click menu.

Another method of copying existing units is to select the unit, hold down both

the left mouse button and the Ctrl key while hovering over the unit and then

with both these held down, drag with the mouse to the location where you

require a copy to be placed. Letting go of the mouse button will then drop a

copy into this position.

Which of these methods you use is a matter of preference.

Position

Equipment

Equipment units may be moved around the flowsheet window, providing that

the flowsheet is not locked. Simply place the cursor over the equipment to be

moved, click & hold down the left mouse button and drag this equipment to

your preferred location. Now release the mouse button to drop the equipment

into its new position. If there are streams attached to the equipment, they will

remain attached while the equipment is being moved. You may sometimes

need to modify the route taken by the streams associated with equipment you

have moved, for aesthetic reasons or to restore clarity to the flowsheet. The

manipulation of streams on your flowsheet is covered under the next topic.

Change

Equipment

Appearance

You can also change the appearance of individual equipment items. Double

click the equipment on the flowsheet or right click and select Properties from

the right-click menu to bring up the Component Properties window. You can

then use the Line and Fill tabs, to modify how this equipment appears on the

flowsheet. For instance, the fill colour, outline thickness and outline colour

may all be altered using this function. You can click Apply to check the



appearance after your changes while the Component Properties window is still

open.

Name

Equipment

The equipment can be named and labelled for ease of identification. Steps 7

and 8 detail the procedure for naming and labeling equipment.

Step 7 Ensure the flowsheet is unlocked. Place the cursor over an item of

equipment and double click to open the Component Properties

window for that equipment. The Name field will be activated by

default on opening this window. Type in the new equipment name,

and then click OK. For this exercise, name the equipment items as

shown in the illustration below.

Remember that the Component Properties window may also be

accessed by right-clicking on an equipment unit and selecting

Properties from the pop-up list.

Label the

Equipment

Step 8 Once you have defined the names, click on the Equipment Auto

Labels button or select the Equipment Auto Label item from the

View menu. The labels will then appear on the flowsheet above the

equipment. To remove these labels click on the Equipment Auto

Labels button again or select this item from the View menu again.

These are equivalent and both act as on-off toggles.

Remove or Re-

position an

Equipment

Label

The labels for individual items of equipment may also be removed if desired by

double-clicking on the equipment, selecting the ‘Auto Labels’ tab and

unchecking the ‘On/Off’ check-box. This enables the user to only display

selected equipment labels. In the above flowsheet we have disabled the

equipment labels for the two water addition units.

Auto labels may be formatted by selecting ‘Equipment Auto Label Properties’

from the ‘Edit’ pull-down menu. This option allows changes to font size, style

and colour, as well as allowing changes to the background colour and line

thickness and colour of the equipment label itself.

Equipment labels can be moved by double clicking on the unit or the label. In

the resulting Component Properties dialog box, choose the ‘Auto Label’ tab and

change the position of the labels by selecting from the options under the Auto



Label Position heading.

Change the

Feed Direction

(The Flip

Buttons)

The orientation of equipment can be changed so that the feed end is facing left

or right, as required. In the next step you will change the feed direction for the

ball mill and its pump on your Learner Flowsheet.

Step 9 Ensure the flowsheet is unlocked. Place the cursor over the ‘Pump

Sump’ equipment item and single click to select. Click the ‘Flip

Vertical’ button on the toolbar to create a mirror image of the

equipment. Repeat this sequence for the ‘Ball Mill’.

Note that the Flip Horizontal button would be used less frequently since most

equipment icons are designed to look recognizable in their default orientations.

However, for some icons (e.g. the water feeder), flipping horizontally does not

make them look odd and it may sometimes be useful.

Auto Save

Function

The first stage of building the flowsheet is complete and the flowsheet should

look similar to the one shown below. Remember to save the project regularly.

Note that JKSimMet has an auto save function that will save the current project

approximately every 3 minutes. This is done in the background and the user

should not notice it happening. If for some reason the program crashes, the

auto saved project can then be opened on re-starting the program and saved

with the appropriate file name.



Tips for Adding

Equipment

The size (and proportions) of an equipment item on a flowsheet can be

changed if required. After clicking on the item to select it, a series of grey

squares will appear around its perimeter. If the cursor is placed over one of

these squares, it will change into a short line with an arrowhead at each end.

When this cursor appears, hold down the left mouse button and drag to

change the size of the item. Note that if you drag one of the corner squares, both

the height and width will be modified simultaneously. Also when you use a

corner square, if you hold down the Shift key while you are dragging the

mouse, then the existing height/width ratio will be maintained.

Matching

Equipment

Dimensions

When equipment has been resized it is possible to match other pieces of

equipment to the same size. Select the different sized pieces of equipment by

holding down ‘Ctrl’ or ‘Shift’ and clicking the desired items. Once selection is

completed, there are three buttons on the toolbar that can be used to resize the

equipment. These are the ‘Same width’, ‘Same height’ and ‘Same size’ buttons.

The selected equipment will all be resized to match the item of equipment

surrounded by the grey squares. This means that the item with the required

dimensions has to be selected last. If selected first or anywhere else in the

sequence, it will not have the grey squares around it. Note however, that if you

forget and select it first, you can simply select it again at the end of the

sequence - without having to start the selection sequence all over again.



Changing

Orientation of

Equipment

Along with the ‘Flip Vertical’ button and ‘Flip Horizontal’ buttons discussed

earlier, there are a number of other buttons in JKSimMet that can be used to

change the orientation of a particular piece of equipment. These buttons are

also located on the Draw toolbar and are the 'Rotate', ‘Rotate Left’ and ‘Rotate

Right’ buttons. The Rotate Left and Rotate Right buttons will rotate the

selected item anti-clockwise and clockwise respectively, by 90 degrees, each

time you click on them. Intermediate angles of orientation can be achieved

using the Rotate button. When you click on this button and then move the

mouse over the selected item, you will see the cursor shown below. Move this

cursor to one end or one side of the item, hold down the left mouse button and

drag around in the direction of the rotation required.

Aligning

Equipment

Items

If the user wants to ensure that several pieces of equipment on the flowsheet

are exactly aligned with one another, there are a number of tools for doing this.

There are six buttons on the Draw toolbar for aligning equipment tops, middles

(horizontal), bottoms, left sides, centres (vertical) and right sides. To use the

align tools, select the equipment to be aligned by pressing ‘Ctrl’ while clicking

with the mouse on the desired items. Again, the piece of equipment surrounded

by grey squares is the one to which the rest of the equipment will be aligned

and thus it needs to be selected last. Once your selection is made, press the

desired align button on the toolbar.

Spacing

Equipment

Items

Different pieces of equipment may also be evenly spaced both horizontally and

vertically from one another. To do this, select multiple pieces of equipment in

the usual way and press the ‘Space across’ or ‘Space down’ buttons on the

toolbar.



Moving a Group

of Equipment

Items

If you wish to move a whole block of equipment items, you need to first select

them as a group by dragging your mouse around them with the left button

depressed. Each unit inside the area you have delineated will now be

surrounded by squares to indicate selection. The units highlighted in this way

can be moved as a group by clicking and dragging any one of the selected

units.

Adjusting

Equipment

Positioning

As an alternative to the gross movement of an equipment item that is normally

achieved through clicking and dragging, very small adjustments to the location

of an item can be achieved using the ‘Nudge’ function. Select the item and then

use the appropriate ‘Nudge’ button on the toolbar to move it a very small

amount in the required direction. This function is particularly useful

immediately after you have added the connecting streams. When first added,

sections of the streams may not be perfectly orthogonal. This can be rectified by

nudging the equipment one or more times as required, in the appropriate

direction.

4.2.5 Add Connecting Streams

Add Streams to

the Flowsheet

The next step is to create streams to join the equipment units that have been

placed on the flowsheet. Note that for the flowsheet to operate correctly, all

input and output ports must have feed and product streams respectively

connected to them.

The flowsheet must be unlocked in order to add streams.

Add Streams Step 1 To begin the stream connection:

Move the cursor to a position over the feed or product port of the

equipment to which a stream is to be connected, in this case the

product port of the Feeder equipment. Note that product ports are

shown as red dots and feed ports as blue dots. When the stream

cursor changes into a circle containing a cross, click the left mouse

button. One end of your stream will now be attached to this

equipment item.

Step 2 To complete the stream connection:

Move the cursor to the feed inlet or product outlet (as appropriate) of

the equipment item that is to be at the other end of this stream. You

must connect product ports to feed ports (or vice versa). You cannot

connect a feed port to another feed port and the same applies to

product ports. In this case you will move the cursor to the feed inlet

of the pump sump. When the cursor is close enough for a

connection to be made, it will change back into a circle containing a

cross. When this happens you can click the left mouse button again

and the connecting stream will then be drawn on the flowsheet.

Streams may be connected directly from an outlet to an inlet (or vice

versa) in a straight line, as would be the case following the



instructions above. Often however, you will need to make the stream

lines follow a more complex path to avoid drawing them over the

top of other items of equipment or over other stream lines. Also, for a

neater presentation, you will probably want to have your stream

lines generally follow an orthogonal pattern on the flowsheet, rather

than being oriented at many different angles.

This is easily achieved as follows:

Stream

Inflexion Points

Once you have connected one end of a stream, you can insert points

of inflexion to control the route that the stream takes to its

destination item of equipment. To do this you simply click the left

mouse button at intermediate locations where you wish to have the

steam change direction. Each time you do this, the stream will be

anchored at the current cursor position and you can then move the

mouse in a new direction, either to make further points of inflexion

(as required), or else to the connection port on the target equipment

item.

You can later move the points of inflexion, if required. When you

hover the mouse cursor over an inflexion point, you will see that it

changes to a little square with tiny arrow heads pointing away from

each side of the square ( ). You can now hold down the left mouse

button and drag to the required new location.

Further points of inflexion can also be added after the stream is

completed. Start by selecting the stream and then hovering the

mouse cursor over the straight line part of a stream where you wish

to place the new point of inflexion. The cursor will initially have the

symbol that indicates the stream can now be moved ( ). However,

when you hold down the Control key, the cursor will change to

indicate a new point of inflexion can be inserted ( ). Now to

complete the insertion, just left- click the mouse.

You can delete points of inflexion if you have added more than you

need. This is achieved by first selecting the stream and then holding

down the Control key as you hover your mouse over the point you

wish to delete. When close to an inflexion point, the cursor will

change to a cross ( ) and you can then left-click to complete the

deletion. The stream will revert to a straight line joining the points

on either side of the one deleted.

Step 3 Repeat steps 1 and 2 to continue connecting the streams in the

flowsheet until the flowsheet looks similar to the one shown below.

For the Cyc O/F stream, follow the normal procedure but simply

double left click when the end of the stream is where you want it.



Tips for Stream

Connection

Feed ports can have multiple streams connected to them. The

maximum number of feed streams able to be connected to any

equipment unit in JKSimMet is currently 50.

Product ports can only have one stream connection. If a product

port already has a stream attached and you are attempting to

connect another, you will find that the cursor does not change to

give it's normal "connection available" signal as you approach this

port. Clicking the mouse over this port will not make another

connection.

If you have changed the location of a unit or a stream node and you

then find that a vertical section of stream is no longer quite vertical,

you can usually fix this by moving the equipment that it comes from

slightly. The Nudge buttons have been provided to make it

easier to achieve this. If moving the equipment slightly doesn't

correct the problem, a small adjustment to its size probably will.

To connect to a unit, a stream must go all the way to the relevant

product or feed port. You cannot connect a stream into another

stream that is already connected to the required port. However, new

streams may partially follow the same path to that port, giving the

appearance of a stream to stream connection.

Errors in

Connecting

Streams

JKSimMet will not allow connecting streams to be drawn that could not exist in

a real plant. For example, JKSimMet does not allow streams to be drawn from

one product outlet to another.

Redraw Note that streams will remain attached if equipment units are moved after they

have been connected by streams. Be aware however that this may result in an

incomplete stream display upon completion of the move. In this case you can

use the Redraw button on the Flowsheet toolbar to redraw your flowsheet. This

should correct any problems that might have become evident as a result of your

editing.

Naming the

Streams

When you create new streams on a flowsheet, they will all be allocated names

automatically by the program. However, these names may not be very

meaningful to you. Thus it is recommended that you change the names so that

they will be easily recognised during data analysis and later when they appear

in your reports.

Step 4 Double click on a stream or right click on the stream and select

72



‘Properties’ from the right-click menu. This will open the

Component Properties window. Type in the new stream name then

click OK. Repeat for all streams. Rename the streams as shown in

the screen grab below.

Adding Labels

to the Streams

The names that you allocate to the streams can be made to appear on your

flowsheet as stream labels (see below). To do this, click on the Stream Auto

Labels button or select Stream Auto Label from the View menu. Note that again,

both the menu item and the button act as toggles, so clicking either again will

make the labels disappear.

The Stream Auto Labels may be formatted by selecting Stream Auto Label

Properties from the Edit pull-down menu. This option allows changes to font

size, style and colour, as well as allowing changes to the background colour

and line thickness plus the colour of the stream label itself. The screen grab

below shows our flowsheet with both the Equipment and Stream Auto Labels

switched on.

Location of a

Stream Label

Individual stream labels can be moved to one of several alternative locations

relative to the stream line. For instance the Cyc Feed stream label above has

been re-set from the default location so as to be closer to the cyclone.

To change a label location, first double click on the stream or the label to open

the Component Properties dialog box for that stream and then select the

Drawing tab. You can then change the position of the stream label by selecting

from the various options under Auto Label Position.



A further addition that can be made on this tab is to add an arrow head to

indicate the direction of flow of a stream. If you wish to do this, click the On/

Off box in the End Arrow section and click OK after selecting the desired arrow

head length and width.

Hiding

Individual

Stream Labels

Note that on the Drawing tab of this dialog box, there is also the option of not

displaying the stream label for the selected stream. If the On/Off check box to

the left of the position radio buttons is unchecked, then the label for this stream

will no longer appear when the Stream Auto Labels toggle is switched on. If

there are a number of stream labels that you don't wish to have displayed, then

you can arrange this by first doing a multiple selection of the streams

concerned. Then just select Properties from the right click menu and uncheck

the On/Off check box.

Changing

Stream Line

Appearance

Changes can be made to both the thickness and colour of stream lines. Again

double click on a stream in the flowsheet and select the Line tab in the

Component Properties dialog box. If you change the selection for either one of

these properties, you will see that the Apply button will become activated. If you

wish, you can use this button to check the effect of the change you are

proposing to make, without closing the dialog box. Note however that pressing

cancel will not undo this change. If you are not happy with the modified

appearance, then you need to click on the line width or style that was originally

selected, before you pressed the Apply button. Alternatively, if you are confident

that your selection will give the desired result, you can just click on OK to close

and keep your modifications.



Delete a Stream Streams can be deleted in the same manner as equipment. First ensure the

flowsheet is unlocked and single click on a stream. Press the ‘Delete’ key or

select ‘Delete’ from the ‘Edit’ pull-down menu. A dialog box will be displayed

asking you to confirm.

Text Boxes To add labels that are not associated with any streams or equipment, click the

Text button and then move the cursor onto the flowsheet. A single click will

place a text box on the flowsheet. The size of the box can be adjusted by clicking

on and dragging the handles, when the text box is selected. The text within the

box can be altered by double clicking the box and entering the desired text.

Pressing the ‘Enter’ key completes the text addition.

The appearance of a text box can be changed by right-clicking on the box and

selecting ‘Properties’. The resulting Component Properties window allows the

user to change the text font, colour and size, as well as the box fill colour, line

style and line thickness.

Text boxes may be removed in the same manner as equipment – single click the

text box to select it and press the ‘Delete’ key or select ‘Delete’ from the ‘Edit’

pull-down menu. The orientation of text boxes can be changed in the same

manner as equipment by selecting the ‘Rotate’ of ‘Flip’ buttons from the toolbar.

Note that if you edit the text from within the Properties window (as opposed to

editing directly in the text box), when you subsequently close the Properties

window, the text box will automatically resize to neatly accommodate the

revised text. You can over-ride this auto sizing however if you wish; just select

the text box and drag on one of the selection handles to modify its size.

Step 5 Now add a text box to your flowsheet and edit the text so that it just

contains the name of this flowsheet (Learner Flowsheet).



The flowsheet required for this exercise is now complete.

At this stage it is advisable to lock the flowsheet by clicking on the Lock button

or by selecting Lock from the Flowsheet sub-menu. When the flowsheet is

locked, adding and removing streams and equipment in the flowsheet is not

possible. Locking a flowsheet also allows users to access the equipment data.

Saving the flowsheet at this point would also be advisable.

4.2.6 Define System Properties

Once your flowsheet has been finalised with all equipment in place and

connected by streams to form a circuit, the data associated with this flowsheet

can be entered. The first step is to define the system property classes required

for a particular flowsheet.

Open System

Properties

Step 1 Ensure the flowsheet is locked, then click on the System Properties

button ( ) or select System Properties from the Flowsheet menu.

Note that if the flowsheet has not been locked, then Lock should be

the only available item on the Flowsheet menu. Click on the Lock

item and then select the Flowsheet menu again. The other items

should then be available.

The System Properties window when first opened, should look

similar to the one shown below.



Step 2 You will notice there is a Select property drop-down at the top of

this window. The system properties are divided into two

categories, Elements and Miscellaneous. When the window first

opens, Miscellaneous is selected as the default. With this item

selected, the two parameters to be configured are Solids SG and

Liquid SG. These are required for the comminution modelling

functions in JKSimMet.

Change the Solids SG value to 2.8 and leave the Liquid SG value

on the default setting of 1.0 for water.

Close System

Properties

Step 3 Click on the Close button to close the window.

Remember to save your project regularly.

Set the Sieve

Series

Step 4 The next step is to set the series of screen sizes that will be used for

this project. Again select the Flowsheet menu and the next item

down from System Properties, which is Sieve Series.

A window similar to the one shown below will then open, which

will already have a default sieve series listed.



You would normally need to change this default series into

something more appropriate.

You can make this change by typing in the individual values or you

can copy and paste a series of values. Note that unless you are using

the copy and paste method, you will first need to type a zero in the

Size 1 cell (immediately below top-size), before typing in your new

top-size value; otherwise it will just return to the default of 200 when

you press the Enter button.

To copy in a series of values from a spreadsheet or from another

JKSimMet file, first select the list of values and copy them onto the

clipboard. Then back in JKSimMet, select the Top-size cell and press

the Paste button ( ) or Ctrl V. The program will automatically

place a zero below the last size pasted and will grey-out all sizes

below this.

Another alternative is to type in a top size and then press the root 2

button ( ) located in the toolbar above this list. This will cause the

program to fill in a root 2 series below the entered top size. Note

again that you need to type a zero into the Size 1 position before a

new top-size value can be entered. Once you put in the required top-

size, press the root 2 button and a root 2 sieve series will be inserted.

This will extend right to the bottom of the available aperture

definition rows. To complete the sieve series definition, you will now

need to type a zero below the smallest aperture in your sieve series.

This will once again grey-out all of the fields below this size.

Note that there is space for adding as many as 40 sizes, but it would



be rare to need anything approaching this.

You should now enter the values shown in the screen grab below.

We are just going to use the one sieve series for all streams in this

case. The program does allow for you to use different screen sets for

different streams for data input but the Master sieve series is used

for balancing, fitting and simulating. The two buttons to the left of

the root 2 button are for adding or deleting additional columns of

sieve sizes. Note that you cannot delete the Master sieve sizes

column - there must always be at least one set of sieves for any

project. In cases where you have added an extra column of sizes, the

Stream table to the right allows you to select which of the alternative

sieve series is to be used for the different streams in your flowsheet.

When you press the OK button, you may get a warning like the one

below.

Its purpose is to remind you that if you did have any data already

entered, changing the sieve series being used will result in the

resetting of your entered data to zeros.

4.2.7 Feeder Equipment Data

In JKSimMet the feed stream data are actually entered in the feed equipment

rather than as a ‘feed stream’. Note that the system properties have already

been defined via the System Properties window.

In this section, data will be entered for the Feeder equipment



Open Equipment

Window

Step 1 Ensure the flowsheet is locked, then double click on the feeder

equipment item in the flowsheet to open the Equipment window.

This window will appear similar to the one illustrated by the

screen grab below.

Enter the Totals

Tab Data

Step 2 By default the Totals tab is selected when this window opens.

Enter the numbers shown in the white cells of this screen grab.

Don't worry about entering any data in the SD or Bal data columns

at this point.

Data Field

Colour

Conventions

General Note: There are three different background colours used to indicate

the different categories of data present in the JKSimMet windows:

1. White – the user is required/permitted to enter data (e.g. feed

tonnage).

2. Light grey – these data cannot be changed (e.g. labels).

3. Medium grey – user entry is not required but the data will change

depending on a user selection or calculation during simulation (e.g.

TPH water).

Enter the Sizing

Data

Step 3 Now click on the Sizing data tab and the window will change to

something like the one below; except that all the Exp column

values will be initially set to either zero or 100. Now enter the

experimental values for these sizing data, as shown below. Note

that you can enter these data using the normal Ctrl C for the copy

operation in Excel, followed by Ctrl V for the paste operation in

JKSimMet, once you have selected the top cell of the sizing data

range.

Note however, that in order for the data you enter to be interpreted

correctly, you must ensure the appropriate button is selected on

the main tool bar, so that it matches the form of the sizing data you

are pasting or typing in. The alternatives are % retained ( ),

cumulative % retained ( ) and cumulative % passing ( ). In

this case we are typing in cumulative % passing data, so make

sure the appropriate button ( ) is selected before performing the

paste operation.



For this exercise, there is no requirement to fill in data on the other two tabs.

These tabs are for the entry of assay data and such data are not needed since

here we are carrying out a comminution simulation exercise. Once more you

should save your project at this point.

4.2.8 Select Equipment Models

After the system properties have been defined and the feed stream data has

been entered, the models for each equipment unit should be selected and the

relevant parameters entered. The Equipment and Model windows contain all

of the information about the equipment that JKSimMet requires to perform a

simulation task.

As discussed in the previous section, the Feed equipment unit is a special

form of equipment in which the actual feed stream data are entered.

Open Equipment

Window

Step 1 Ensure the flowsheet is locked then click on the Equipment icon on

the toolbar or select Equipment from the Flowsheet sub-menu to

open the Equipment window. This window can also be opened

simply by double clicking on any equipment unit in the flowsheet,

in which case the item of equipment you have clicked on will be

selected by default from the Equipment Name drop-down list.



Select the Ball

Mill

Step 2 Begin by selecting the Ball Mill from the Equipment Name drop-

down list, if it is not already selected.

Select Model for

the Ball Mill

Step 3 Click on the Equipment Model drop-down list to access the model

choices for the Ball Mill and select the Perfect Mixing Ball Mill

model. See under the Model Descriptions topic for further

details on the way this model works, including a description of the

parameters associated with each tab.

Perfect Mixing

Ball Mill Model

Step 4 Click on the double arrow button ( ) located to the right of the

Equipment Model drop-down list to access the data for the Perfect

Mixing Ball Mill model.

The Perfect Mixing Ball Mill model data input screen is shown in the screen

grab above. The first tab (which is selected by default when the window

opens), is the Scaling tab. On this tab you enter the dimensions of the mill to be

simulated, its rotational speed (expressed as the fraction of critical speed), the

loading of the mill, the work index of the ore being treated and the ball top

size. Default values are provided for each of these items when this window is

first opened. For this exercise, you should modify the default values to line up

with the values displayed in the white cells of the screen grab above.

On this tab it is possible to scale up (or down) in cases where the parameter

fitting has been done for a different sized mill to the one that is specified in the

360



current flowsheet. This is the purpose of the right hand table under the

Original Mill heading.

Ball Mill Perfect

Mixing Model -

Rate/Discharge

Function Tab

Step 5 The second tab is the Rate/Discharge Function tab. The values on

this tab are the fitted parameters for the milling operation we are

about to simulate. In this case we will again leave these values at

their default settings.

Note that you have to close the equipment and model parameter

windows by just clicking on the cross at the top left corner. There

is no Save button on these windows, but the entered values will

remain in memory and will be saved when you press the Save

button on the main window toolbar or else when you close the file

(provided you elect to save it when prompted).

Water Feeder -

for Ball Mill

Cyclone Feed Bin

Step 6 Double-click now on the water feeder associated with the cyclone

feed sump. This will bring up the Equipment window for a water

feeder. The screen grab below shows this window activated with

the Equipment Model drop-down expanded.

For the model we will select the Required % Solids model. After

you have selected this from the drop-down, click on the double

arrow button beside this list to access the properties of the chosen

model.



For this model, the only value to be entered is the required % solids

value. We will select 58% as the required % solids, which will then

be the pulp density of the feed to the ball mill cyclone. Close the

equipment window for the water feeder.

Water Feeder -

for Ball Mill Feed

Stream

Step 7 Now double-click on the Ball Mill Feed water feeder and perform

the same sequence, this time selecting 73% as the required % solids

value. With this model and this parameter value selected, the

water flow will be adjusted during the simulation so as to achieve

73% solids for the pulp density of the total feed to the mill. Close

the equipment window for this water feeder.

Cyclone - Model

Selection

Step 8 Finally, we need to select the model and set the operating

parameters for the cyclone. Double click on the cyclone icon on the

flowsheet and you will bring up an equipment window for the

cyclone, as shown below.

From the Equipment Model drop-down, select the Narashima/

Mainza model as the model to be used. Once you have made this

selection, click again on the double-arrow button to set the

parameters for this model. Enter the cyclone dimensions and the

other operating variables on the Operating Condition tab as shown

below.



Cyclone Model -

Setting

Parameters

Then select the Model Parameters tab and enter values as

indicated in the following screen grab.

Once these are entered, close the model parameters window for the

hydrocyclone.

Models have now been selected for all of the equipment and the

flowsheet is ready to be simulated.

Remember to save the project.

4.2.9 Simulation

Now that your flowsheet has been set up with models assigned to all

appropriate equipment items and values have been entered for their relevant

parameters, you can proceed with a Simulation of this circuit.

Open the

Simulate

Window

Step 1 Ensure the flowsheet is locked and then click on the Run

Simulation icon (large icon in left panel toolbar) or select Run

Simulation from the Flowsheet menu to open the Simulate

window. This window together with the main window behind it,

is shown in the screen grab below. All the equipment items and



streams are highlighted in heavy blue to indicate that they are all

initially selected.

You will notice that by default the Simulation Select List drop-

down displays 'Whole Circuit'. Initially this is the only select list

available. You can however add your own select lists if you wish

to simulate certain parts of the circuit in isolation. For this exercise

however, we will be simulating the whole circuit only.

Note that the check boxes for selecting and de-selecting individual

items of equipment and streams can only be modified once you

have defined (and selected from the drop-down), your own partial

circuit for simulation. When defining a partial circuit, you will

notice that as you select streams or equipment items from the list,

they become highlighted on the flowsheet (in heavy blue), to

indicate selection. A partial circuit consisting of the cyclone and

its feed and product streams is shown in the screen grab below.

If you try this, be sure to select the Whole Circuit from the drop

down box before continuing.



Adjust the

Simulation

Settings

Step 2 In the Settings region, you will see that the default Convergence

limit is set at 0.0000001 and the default number of Iterations value

is 1000. Both of these values can be left at their default settings.

The Interpolation can be left as Spline and the Starting Condition

as Experimental.

Run Simulation Step 3 Click on the Start button to start the simulation. It also displays

the convergence value and the number of iterations that the

simulation algorithm has performed to reach convergence, see

below. These values are updated while the simulation is

proceeding.

Completed

Simulation

The iteration count will proceed until either convergence to the defined

convergence value has been reached, or the maximum number of iterations

has been reached, whichever occurs first. This flowsheet should simulate to

convergence in about 70 or so steps, if set up as described.

Close Simulate

Window

Step 4 The simulation of this flowsheet is now complete. To close the

Simulate window, click on the cross in the top right hand corner of

the window.

4.2.10 Viewing the Results

The results of the simulation can be viewed in the Configurable Stream Overview

window. This window allows the user to view the stream statistics calculated

during simulation for one or more selected streams. The user can choose which

data and which streams are displayed. However, when you first open this

window, all the streams in your flowsheet will be listed by default. You can

either modify this view of the data or add other alternative views that you can

build to satisfy your own requirements.

Open

Configurable

Stream

Overview

Step 1 Ensure the flowsheet is locked, then click on the Configurable Stream

Overview icon or select Configurable Stream Overview from the

Flowsheet menu. The Configurable Stream Overview window will

then open. The window will look something like the screen grab

below. From the Select List drop-down, you can select the type of



data you wish to view. In this case we wish to view the simulated

data, so select 'Stream Data (Sim)' from the drop-down.

Note that the screen grabs below are incorrect in one respect. The

grabs were taken from an earlier test version of the program and the

cells in some of the simulated data columns appear white. In fact all

columns containing simulated data should be grey, to indicate they

cannot be edited.

The Function

of the Lock

Button

Some aspects of this table's layout can be modified. The Lock button ( ) on

this Window's toolbar acts as a toggle that determines the functionality of

certain actions in terms of the table configuration changes that can be achieved.

If the Lock button is down, you can add columns and rows to the table. Also

with the button in this position, clicking on a column header will bring up a

dialog box for setting up the contents of the selected column. If the Lock button is

up, clicking on the column headers does not have the aforementioned affect, but

it will allow you to make changes to the order of the columns and the same for

the rows.

Adding

Columns and

Rows

Step 2 In this exercise we are going to add two extra columns. To achieve

this, the Lock button needs to be in the down or locked position, but

this should already be the case when you first open this window.

First click somewhere within the % Solids column to select this

column. Note; don't click on the title of the column as this will bring

up the dialog for selecting the contents of the column. Now use the

Insert Column toolbar button ( ) to add a column. The new

column will be added to the right of the currently selected column.

Adding a

Column to

Display

Volume Flow

Step 3 Initially, the new column will just have 'No Selection' as its column

header. The next step is to set up this column with the information

that you require it to display. Clicking on the column header will

bring up a dialog box where the contents of the new column can be

specified.



In this case we want a column showing the volume flow in each of

the streams. We will leave the Selection Name set on 'Auto Generate'.

Unchecking this check-box allows you to enter your own name for

the column - which may be useful if you have lots of columns to

display and want to make the headers more concise. In this case you

need to select the options as per the above screen grab and then click

on 'OK'.

Adding a

Column to

Show Solids

Amount

Above a

Selected Size

Step 4 We will add a further column now to demonstrate another feature of

the Selection Options window. Click within the new volume flow

column to select it, then again use the Insert Column button ( ) to

add a further column to the right of the one selected. Again click on

the title bar of the new column to bring up the Selection Options

window. We will assume that for some reason we want to see how

much of the ore in each stream is coarser than 4.75 mm. Again click

on the header bar for the new column. When the dialog box opens,

select Size for Option 1, and you will find that another dialog box

will appear.



Select 4.75 mm from this dialog. When you press OK after this

selection, the value 4.75 will be displayed in the grey box to the right

of the Option 1 drop-down and Option 2 will become available for

selection.

Select 'View As' from the Option 2 drop-down.

This will bring up another dialog box from which you should select

'Cum % Retained'.



Finally, after you have selected 'Cum % Retained' for Option 2, a

drop-down will become available for Option 3. Here you need to

select 'Simulated' for the data type that will be displayed.

When you OK this selection, the overview will look something like

the one below, with a new column showing the amount of solids that

is coarser than 4.75 mm in each of the streams.



Stream Order

and Column

Order

Changes

Step 5 The order that the stream names appear in this table is the same

order in which their associated equipment items were added to the

flowsheet when it was first drawn. To change this order, you need to

first click on the Lock button - so that is in the up or unlocked

position. In this exercise we will just move the Cyc feed Water down

to the bottom of the table.

Now click the left mouse button while hovering your mouse over the

name cell for stream (row) that you wish to move (i.e. in this case the

Cyc feed Water stream).

With the mouse still over this row, hold down the left mouse button

and drag this row to its new location. As you move the mouse,

potential new locations will be marked by a red line. When you are

satisfied with the indicted new position, let go of the mouse button

and the required change will be completed. The same method can be

used to change the relative location of columns in this table.

The screen grab below shows the Cyc feed Water row in the process

of being moved.

Note that you can select multiple adjacent rows or columns by just clicking,

holding down and dragging - provided that the column or row you begin this

process on has not already been selected. Once the required group of rows or

columns has been selected, you can then click, hold-down and drag again and

this time the dragging process will move the selected group into a new position,

as indicated by the red line.

We have now set up an overview to show the results of our simulation. For more

information on the Configurable Stream Overview and its capabilities, go to the

topic Using the Configurable Stream Overview .

In the real world, you would be looking at these simulation results and

assessing whether this circuit is achieving the required results and if not,

considering what changes might be made to improve the situation.

After an analysis of your simulation results, the circuit configuration could be

altered and/or the capacity and characteristics of the equipment items changed

before repeating the simulation process. There may be several iterations of this

sequence required before you are satisfied with the results being obtained.

Finally, don't forget to save your project after a session such as this, to protect

against losing your work in the event of a power outage or other mishap.

4.2.11 Viewing Individual Stream Data

A range of different stream statistics calculated during simulation can be viewed

using the individual stream data windows.

213



Open Stream

WindowStep 1 Ensure the flowsheet is locked then click on the Stream button ( )

or select Stream from the Flowsheet menu to open the Streams

window. This window can also be opened by right-clicking

anywhere on the flowsheet and selecting Stream from the drop-

down menu.

All streams in the flowsheet can be accessed from the Streams

window. The Streams window also shows the equipment items that

the currently selected stream is flowing from and to.

Select Data to

view

Step 2 The user can, from this point, choose to view the data for any of the

streams in the active flowsheet by first selecting the required stream

from the Stream Name drop down and then clicking on the double

arrow to the right of this drop-down to open the Stream Data

window.

An alternative method of getting at the Stream Data window for any

individual stream is to double-click directly on the line representing

that stream on the flowsheet. This will open the Stream Data

window for the stream directly, without going first to the Streams

window.

Stream Data

Window

The layout of the Stream Data window is the same for every stream. A tabbed

interface is used to display the different categories of stream data. The first tab

shows the Total values for the stream, including the TPH Solids, the TPH Water,

% Solids values and others. The other three tabs are labelled Sizing Data,

Elemental assay data and Size by elemental assay data respectively.



Click on any of the four tabs to view the data in the relevant categories. On each

of the tabs, there are columns to show the types of data associated with the

parameters listed on that tab. For example, on the Totals tab is a column for the

SD (standard deviation) data. This is where a reliability estimate is assigned to

the individual parameters that have been measured for this stream. Larger SD

values indicate reduced confidence in the experimental value and allow the

program to move further away from these values during balancing.

Viewing the

Sizing Data

Step 3 To view the sizing data, click on the second tab of the Stream Data

window. The row labels will now be the screen sizes that have been

previously entered. Note that at any time you can change the way the

sizing data are expressed throughout the program, using the buttons

on the main toolbar.

The sizing data can be expressed as either % Retained ( ), Cum %

Retained ( ) or Cum % Passing ( ).



On the other two tabs are the Elemental Assay Data and the Size by Elemental

Assay Data. On these tabs, the data types displayed are limited to Exp, SD, Mbal

and Error. This is because in JKSimMet, none of the models deal with

predictions of assays and we are not generally dealing with processes that

result in any differentiation in grade.

Copying Data

into Excel

Step 4 To copy data from the tab that is currently chosen, first select the

required data, then click on the copy button ( ) located at the far

right of the Stream data window toolbar - as shown below.

If you then open MS Excel, you will be able to paste the current data grid into the

active sheet, with your chosen cursor position being the top left hand corner of

the grid.

Close

Windows

To close the Stream data and Streams windows, click on Close ( ) in the top

right hand corner of the windows.

4.2.12 Viewing Data for Multiple Streams

The Configurable Stream Overview feature allows the user to view the stream

statistics calculated during simulation, mass balancing or fitting for one or more

selected streams. The user can choose which data types and which streams are

to be displayed.

Opening the

Configurable

Stream

Overview

Step 1 Click on the Configurable Stream Overview button ( ) to open the

Configurable Stream Overview window. If no overview tables have

been set-up previously, the window when first opened will still

contain a default table with some flow and % solids data and all of

the size fractions that have been entered for the project concerned.

There are a number of pre-configured overviews with different

combinations of data types. The user can select an appropriate one of

these via the Select List drop-down in the upper left-hand corner of

the window. The screen grab below has captured this process, with

the user in the process of making a selection.

If one of the pre-configured overviews does not satisfy your needs,

then there are plenty of tools provided for modifying an existing

overview or for creating a new overview and setting this up precisely

to your requirements.

Creating a

New Stream

Overview

Step 2 To create a new Overview, click on the New Stream Overview button

( ) which will bring up the Add New Stream Overview dialog.

Type a name for the new Overview here and then click on the OK

button.



The Configurable Stream Overview will then re-open with a default

range of stream statistics as shown below. The user can then add or

delete rows or columns to display only the required data for this

particular overview. Note that data can be entered via the

Configurable Stream Overview, in any cells that have a white

background.

Remove

Unwanted

Streams

Step 3 For the practice, we will assume that you don't wish to display the

data for the Cyc Feed in this overview. To remove it from the display,

click anywhere in this row and then click on the Delete Rows ( )

button.

Add a Data

Column

Step 4 To insert an extra column, click in any column of the table and then

click on the Insert Column button ( ). This will add a blank

column to the right of the cursor. The new column will just have "No

Selection" as the header and all of its fields will initially be grey; as

illustrated in the screen grab below. Note that you can also add a

new column that is a replica of an existing column. To do this you

click in one of an existing column's cells and then click on the Copy

Column button ( ). When you do this, a replica of the selected

column will be placed immediately to its right. This may be more

efficient if the column being added is to be very similar to an existing

column, but with just the data type changed perhaps or the mode of

display changed - e.g. from % Retained to Cum % Retained.

Define the

Data Shown in

a Column

Step 5 To define the data that is to be shown in the new column (or to

modify what is shown in an existing column), click on the header

row of the new column to open the Select Options dialog box. Select

the required stream statistic from the Option 1 drop-down list. In this

case select "%Solids", then from the Option 2 drop-down list select



"value" and from the Option 3 drop-down list select the type of data

to be displayed (e.g. experimental, simulated etc.).

Export the

Configurable

Stream

Overview

table

Step 6 The data presented in the table can be exported to Excel by clicking

on the Export Overview button ( ), or on the Export All button (

) if more than one stream overview exists. Alternatively, by

clicking on the Copy Grid button ( ), the data can be copied to the

clipboard for pasting into other documents (e.g. a Word document).

Clone the

Configurable

Stream

Overview

table

Note that the user is able to create clones of existing tables in the Configurable

Stream Overview by clicking on the Clone Overview button.

4.2.13 Finishing a JKSimMet Session

Ending the

JKSimMet

Session

Step 1 To quit from JKSimMet click on the cross in the top right hand

corner of the session window or select Exit from the File menu. A

JKSimMet prompt will ask to save the changes if changes have

been made and not yet saved. Click on "Yes" to save any changes.

Simulation of the simple comminution circuit has been completed and the

simulation data have been examined. In the next exercise the operation of the

circuit will be changed by varying the parameters of some of the components,

and then running simulations to observe the predicted results.

Before doing this, end the JKSimMet session as explained above.

4.3 Working with an Existing Project

About this

Section

Now that a simple comminution circuit has been successfully simulated, this

exercise will demonstrate how to:

Version 6.0.1 - March 2014Working with an Existing Project


Change some of the input data and flowsheet configuration in an

attempt to improve the performance.

Re-simulate the circuit.

View the results.

The objective is to optimize the performance of the circuit by changing key

parameters. The parameters are those characteristics of the equipment or

streams that can be altered. In a real plant most equipment parameters can be

altered (with varying degrees of difficulty and with varying degrees of

expense!). A few stream parameters such as the mass flow rate can also be

varied. It is however difficult and costly to experiment with real equipment;

simulation using JKSimMet allows the engineer to make a wide range of

changes easily and then view the predicted results. The selection of these

parameters is the engineer’s job and you may wish to experiment; this section

will take you through the steps for a number of changes.

The general technique is to first decide on the parameter changes you wish to

make, then select the equipment concerned and make the changes, re-simulate

the circuit and finally observe the results. These results can then be accepted

and saved as a permanent record; further changes can be made and the

process of simulating and assessing the results repeated.

4.3.1 Selecting the Flowsheet to Use

The procedures used when working with an existing project are very similar

to those outlined under the heading Building a New Project .

Start JKSimMet Step 1 Start JKSimMet by following steps 1 to 4 under the heading

JKSimMet Start Up .

Load an Existing

Project

Step 2 Click on the Open Project icon on the toolbar or select Open

Project from the File menu. This will open the Open JKSimMet

Project dialog, which displays the previously saved projects.

Select the ‘Learner Project’ that was created while working

through the Building a New Project section and then click Open.

Loading a Project

when Another

Project is Still

Open

JKSimMet closes an open project before opening a different one. If opening a

project is attempted when another project is still open, JKSimMet will prompt

to save the open project where changes have been made since the file was last

saved.

Step 3 To prevent the Learner Project from being overwritten, select Save

Project As from the File list then type in the new project name; for

example use ‘Learner Project – Changed Cyclone Params’ as the

new name, and click OK.

Note however, that on occasions when you do wish to deal with two different

projects at the same time, you can open a second instance of JKSimMet and

then use this instance to open the second project. It would be wise though to

avoid having the same project open in both instances. This could potentially

result in problems - especially if you go to save data that may have been

changed in both instances.

59

60

Version 6.0.1 - March 2014 Working with an Existing Project


4.3.2 Working with the Simulation Manager

In this section the cyclone vortex finder diameter will be changed to see how

this affects the size distribution of the final product from the grinding circuit .

While the user can make this type of operating parameter change in the

Equipment window or via the Info Blocks on the screen (see Defining

Equipment Info Blocks ), the Simulation Manager provides a more

convenient means of doing this, particularly when several similar simulations

are to be performed. Note however that with this version of JKSimMet, you

cannot change the feed rate to the circuit from within the Simulation Manager.

This is because the Simulation Manager deals with changes to model

parameters associated with equipment items only. However, it is intended

that in later versions the circuit feed rate will also be made available for

modification via the Simulation Manager interface.

Open the

Simulation

Manager

Step 1 Click on the Simulation Manager button on the toolbar to open the

configuration window for this feature. It will initially be blank as

shown below and the first thing to do is to create a simulation

scenario.

Create a New

Simulation

Scenario

Step 2 Click on the New Sim Scenario button to create a new simulation

scenario. Type the name of the scenario into the dialog that

appears and click on the OK button to access the blank scenario

configuration screen.

When you click on OK, the initial framework for the new

simulation scenario will be set up. This will have a single column,

with "No Selection" as the header.

Configure the

Simulation

Scenario

Step 3 To begin configuring the new simulation scenario, click on the "No

Selection" header and a new dialog will open labelled Equipment/

Tab/Option/Parameter. This dialog appears as shown below.

125



Selecting the

Parameter to be

Changed

Step 4 In this case we will select the cyclone from the Equipment/Group

drop-down, then Operating Condition from the Tab drop-down.

The Option drop-down is not relevant in this case and will not be

available. From the Parameter drop-down we will select Vortex

Finder Diameter - Do (m).

Once you have made these selections, click on the Apply button at

the bottom of this dialog. The Simulation Manager window should

look similar to the image below. You will notice that now the

Simulation 1 cell for the cyclone parameter we have selected is

available for data entry.



Selecting the

Type of Change

and Specifying

the Amount of

Change

Required

Step 5 The new simulation conditions can now be entered in the Cyclone

column. You will see that just above the Original Data label, there

is another row labelled "Type of Change". There are two choices

here. You can specify the actual value for the parameter or you can

specify a percentage change from the original value. In this case

we will reduce the vortex finder diameter by 10% for one

simulation and then increase it by 10% for a second simulation.

By default the Type of Change will be set to "Value". Click on the

drop-down and change this to "% Change". Then click in the

Simulation 1 cell for the Cyclone column and enter "-10". This

simulation scenario will be automatically saved under the default

name "Simulation 1".

Adding a

Simulation

Step 6 As we are going to be doing two simulations, we need to add an

extra row - in addition to the default Simulation 1 row. To do this,

place the cursor anywhere in the Simulation 1 row and press the

Apply Simulation button. An extra row will be added below the

cursor position, with the default name Simulation 2. The new

simulation conditions can now be entered in the Cyclone column -

in this case we will enter the value +10, meaning that we will be

increasing the vortex finder diameter by 10% from its original

value.



Step 7 If you now place the cursor anywhere in the Simulation 1 row,

pressing the Simulate Select button ( ) will run a simulation

using the parameter changes that have been specified in this row.

The same would apply if you placed the cursor in the Simulation 2

row - a simulation would occur with the settings specified in the

Simulation 2 row only.

If you press the Simulate All button ( ), the program will run

simulations consecutively on all of the scenarios you have set up.

Note that only the results from the last one of these simulations

will be available for plotting. Note also that you can press the

Simulate All button from any one of the three tabs. This means that

you can simulate with one of the results tabs active and therefore

immediately see the before and after values.

The results of the simulations just performed can be observed on

the next two tabs, Results - Streams and Results - Equip. You can

set up these tabs to observe any results from the simulation that

you wish to monitor. This is done in a similar fashion to the way

you set up the Simulation Scenario tab

Set up Columns

for the Results

you wish to

Monitor

Step 8 Click on the Results - Streams tab, create a new column by clicking

on the Insert Column button. example of the Results - Streams tab

is shown below where the user is looking at the effect of the vortex

finder changes on the solids flow rate in the cyclone underflow

and P80 in the cyclone underflow.



Notice that the buttons for adding and deleting rows from the table

are not available when you are on either of the results tabs. You

need to return to the Simulation Scenario tab if you wish to set up

further scenarios for simulation. The buttons for adding columns

however are available and these can be used to add any

characteristics of the streams or equipment that you would like to

monitor following simulations under the various scenarios. Note

that you do need to repeat the simulations if you add further

columns because the cells in any new columns will be just

populated by zeros until the simulations have been re-run.

Step 9 Now select the Results - Equip tab, add a column and click the top

row of the column to bring up the dialog for selecting the

equipment and equipment parameters for display. Select Cyclone

from the first drop-down, Perform Data from the second and Op

Pressure from the fourth. Notice that the third drop-down (Option)

is de-activated. It is only required for a very limited number of

equipment types.



When you click on the Close button, another dialog box will

appear where you select the types of data that you wish to

display.

Once you have made the selection and closed this dialog, you will

be returned to the Simulation Manager window, which will now

look something like the screen grab below.



Rename the

Scenario

Step 10 You can change the name of the scenario easily by pressing the

Rename Scenario button. This will bring up a dialog box like the

one shown below. Change the name to something that will be

more suggestive of what the current scenario has been set up to

investigate - in this case perhaps something like "Cyclone Vortex

Finder Changes".

Run a Simulation

on the Selected

Row

Step 11 To continue the exercise, now press the Simulate All button to

carry out simulations according to the conditions set up for both

rows. You will see that the cyclone operating pressure data will

then appear for the two scenarios that have been defined on the

first tab.



4.3.3 Using Model Based Groups for Simulations

Groups -

Principles of

Use

Where you have multiple equipment items that are using the same model, you

can assign these to a group which can then be selected instead of an individual

equipment item. When this is done, any changes in the settings that you make

to the equipment or model parameters for the group will apply to all of the

equipment items assigned to that group. Once you have set up groups, these

will become available as alternatives to just selecting individual equipment

items from the top drop-down list in the Scenario Manager window. Note that

the defining feature of a Group is that all members of the Group will be using

the same model, with the same parameter settings.

Edit Groups

Button

Step 1 In the Simulation Manager window, click on the Edit Groups button

to bring up the Select Equipment for Groups dialog.

Step 2 Click on the Add Group button at bottom left of this dialog. This will

bring up an Add New Group dialog where you can provide a name

for the new group and then select from all possible models

associated with the types of equipment that exist in your flowsheet.



In this case we do not have multiple equipment items using the same model,

but we will go through the exercise anyway to demonstrate how it works.

Step 3 Enter a name, such as "Perf Mix BM Group". This would be a group

consisting of equipment items on your flowsheet that all use the

perfect mixing ball mill model.

Note that you do not have to assign all of the equipment items that use this

model to this group. Some of them could be left outside the group to be set up

individually for simulations. Alternatively, you might wish to have two

groups. For instance you could have "Perf Mix BM Group 1" and "Perf Mix BM

Group 2". Both groups would necessarily consist of mills that use the perfect

mixing model, but each could be set up with different parameter values within

any given simulation.

Step 4 When you close the Add New Group window, you will see the new

group you have added in the right hand panel of the Select

Equipment for Groups window. This new group will initially

contain no equipment items. When you click on it however, you will

be able to see in the left hand panel, all of the equipment items on

your flowsheet that are currently set up to use the model associated

with the selected group.

Now use Ctrl or Shift click on the equipment items from the left

panel to select all of those that you wish to include in the group and

then click on the transfer button to move these items into the

selected group. In this case there is only one equipment item - the

ball mill. Click on this item and then click on the transfer button to

move it into the "Perf Mix BM Group". Just prior to the transfer, the

window should look similar to the one shown below.



After the transfer, the window will look like the screen grab below,

now with the equipment item that was selected from the left panel,

appearing in the right panel, under the selected group.

Now when you go back to the Simulation Manager window and

click on the top row of the table, you will find that the group you

have just added will be available for selection.



Note that once you have assigned an item of equipment to a group, you will no

longer be able to select this item of equipment individually. This is because by

definition, all members of the group will have the same parameter values.

Similarly, once you have set up a column with a particular parameter selected

for a given item of equipment, you will not be able to set up another column

with the same equipment and parameter selections.

4.3.4 Simulating Changes in Operating Conditions

In this example we will look at the effect of increasing ore hardness and how

JKSimMet might be used to investigate ways to compensate for this and thus

maintain throughput at existing levels.

Open the

Simulation

Manager

Window

Step 1 Click on the Simulation Manager button ( ) to bring up the

Simulation Manager window, then click on the Simulation Scenario

tab.

Step 2 Click on the New Sim Scenario button ( ) to create a new

simulation scenario. In JKSimMet, the term scenario is used to

describe a group of related simulations that have been set up to

investigate the effects of changes in a particular set of model

parameters. The individual sets of parameter values are just referred

to as Simulations.

We will call the new Simulation Scenario in this case "Compensating

for Ore Hardness Changes".



Add a New

Simulation

Scenario

Step 3 Now click on the "No Selection" at the top of the default column that

will be present on the Simulation Scenario tab. This will bring up

the Equipment/Tab/Option/Parameter window. Note that you must

have the Lock button ( ) in the down position for this dialog to

activate. From the Equipment/Group drop-down list, select "Ball

Mill".

Step 4 Select Scaling from the Tab drop-down and then select Ore Work

Index from the Parameter drop-down.

Step 5 When you click on the Close button from the above window, a Select

Properties window will open. Here you should just tick the check-

box for "Sim" since the Org (original) values are only relevant for

when you are fitting - not for simulating.



On closing this window you will find that the Simulation Manager

now looks like the screen grab below.

Simulation 1 will be present because this is a default simulation row

that is added by the system. You can change the name of each

simulation if you wish to something more indicative of the

parameter adjustments that have been applied. To do this, you just

click in the relevant cell of the Simulation Name column and made

the required editing changes.

Add

Simulation

Rows

Step 6 Add three more rows to this Simulation Scenario by pressing the

Insert Simulation button ( ) three times.

Add Columns Step 7 Next add two more columns by pressing the Insert Column button (

) twice.

Step 8 Using the same procedure as described above for setting up the first

column, set up the second column for adjusting the fraction of

critical speed that this ball mill is operating at. Similarly, set up the

third column for adjusting the load fraction for the ball load in this

mill.

Step 9 Now change the names of the simulations so that they provide an

abbreviated specification of the parameter changes involved. Also

enter the new parameter values in the columns, as shown in the

screen grab below.

For the first simulation we will just be looking at the effect of harder

ore on throughput when there are no compensatory plant changes

made. We will call this simulation "Harder Ore" and change the Ore

Index value from the original 15.3 to 17.7 kWh/t. For the second

simulation we will increase the mill speed from 74% of critical to

80% of critical and for the third we will increase the mill load from

40% to 45%. Finally, for the last simulation we will increase both the

mill speed and mill load to look at the combined effect. Note that the



higher ore work index should of course be entered for all four

simulations. The Simulation Manager window should now look

similar to the screen grab below.

Step 10 Now go to the Results - Streams tab and set up columns for the

results you wish to observe on running these simulations. Say in

this case we are just interested in the cyclone U/F solids TPH, %

solids and cyclone O/F P80. There will be one column present by

default so you will need to add two more columns. Set these up in

the same way as you have done for the columns on the Simulation

Scenario tab.

Step 11 Once the columns have been set up for the results you wish to

observe, click on the Sim All button ( ) to simulate each of the

plant conditions that you defined back on the Simulation Scenario

tab. The Simulation Manager should now look similar to the one

shown below, with simulated outcomes for each of the sets of

parameter values.



We can see from the values obtained above that with both changes

applied to the mill operating conditions, the simulator is predicting

that production can be returned to the level that existed prior to the

ore hardness change.

Step 12 If we now go to the Results - Equip tab, we can have a look at what

effect our operating parameter changes have had on the power

consumption of the mill. When you click on this tab, there will be a

default column in place - but again it will just have "No Selection" as

the header. Click on this cell and you will again be presented with

the Equipment/Tab/Option/Parameter window.

Step 13 In this window, select "Ball Mill" from the first drop-down and

"Power" from the second. From the Parameter drop-down, select the

total power item for an overflow ball mill.

Step 14 Note that after you have made the selection and closed this window,



the selected parameter identification fields (column headers) back on

the Simulation Scenario window will now be populated. However,

there will be no values filled in for the results of the various

simulations. To see the results, you will now need to run the

simulations again, by pressing the Sim All button ( ). Once the

simulations have been run, your Simulation Manager window will

look like the one below.

So the results from this exercise have indicated that to minimise the

effect of the harder ore and almost restore the circulating load and

product P80 requires an 18% increase in power.

4.3.5 Working with Configurable Equipment Manager

Configurable

Equipment

Manager

The Configurable Equipment Manager window displays a summary of selected

equipment unit parameters. The user can configure multiple summary tables for

display and can edit the values displayed in the tables. This window provides a

simpler and more efficient alternative for reviewing and adjusting equipment

information than using the individual equipment data screens. More information

on the Configurable Equipment Manager is available under the section on

JKSimMet Windows and in the topic Editing Equipment Data .

Step 1 Ensure the flowsheet is locked ( ), then open the Configurable

Equipment Manager window by clicking on the Configurable

Equipment Manager button ( ) or by selecting Configurable

Equipment Manager from the Flowsheet menu. When first opened, this

window will look similar to the illustration below.

153 195



Step 2 Click the New Unit Overview button ( ). This brings up the Add

Unit Overview dialog box.

In this case we will enter ‘Ball Mill Overview’ for the name and select

'Ball Mill (Perfect Mixing)' from the Select Model pull-down list. Since

the flowsheet we have been dealing with for demonstration purposes

has only the one item of each type of equipment, using the

Configurable Equipment Manager in preference to dealing with the

model by clicking on the item of equipment itself does not confer a lot

of advantages. The major benefits of using this option are to be had

when you are dealing with multiple equipment items in your

flowsheet that all use the same model.

Step 3 Click ‘OK’ and something similar to the screen below will appear.



The Default

New

Overview

Window

When first opened, the new overview window contains a single row

labelled 'Ball Mill' because in this case it is the only equipment item in

our flowsheet that uses the Ball Mill (Perfect Mixing) model. If we were

dealing with a flowsheet that had multiple items using this model,

then each of these items would have been listed on a separate row.

The new overview window also contains just the one column to begin

with, which is headed 'No Selection'. This is where we need to carry

out some configuration to display the data that we wish to manipulate

and/or view in relation to the equipment items using this model. To

select the data that you wish to show in any column of an overview,

click on the first line of the column. This brings up a dialog box where

the tabs, options and parameters may be set as is appropriate to

display the required data items.

Step 4 Click the ‘No Selection’ to bring up the Tab/Option/Parameter dialog

box. Let's say that in this case we are interested in the effect of having

a slightly larger mill. We would select 'Scaling' from the Tab drop-

down and then 'Internal Length' from the Parameter drop-down.



When you then close this dialog, the Configurable Equipment Manager

should look like the image below.

Next we would like to look at the effects on the output parameters

associated with this equipment unit such as the power draw of the

mill. We will set up a second column to enable this to be observed.

Step 5 To add an extra column, click on the Insert Column button ( ). Now

click in the first row of the new column to open the dialog box where

the contents of the new column is defined.

Positioning

Columns

Note that you can control the positioning of a new column at the time

of placement. A new column will always be placed to the right of the

currently selected cell. You can also move a column after it has been

placed. To do this you need to first unlock the display ( ), then click

on the column to select it and then click on it again, this time holding

down the mouse button to drag and drop the column to its new

location. Potential new locations will be indicated while you are

dragging it, by a vertical red line between the existing columns. Don't

forget you will need to click on the lock button again before continuing

with other operations.

Deleting

Columns

Note also that is easy to eliminate columns that are no longer needed.

Just click anywhere in the column in question - anywhere that is

except the top header cell, because this would just open the Tab/

Option/Parameter dialog box. Having one of the cells in the column

selected is enough to identify this column as the one to be removed.

Then click on the Delete Column button ( ) to remove it.

Step 6 In the Tab/Option/Parameter dialog box that will have opened after

Step 5, select ‘Power’ from the Tab menu and ‘Total Power (Overflow

kW)’ from the Parameter menu. When you click on the Close button,

the Configurable Equipment Manager should look like the one shown

below.



Step 7 Now take note of the mill power reading and change the mill length

from 7.3 to 9.5 m. You will need to re-run the simulation to observe the

effect of this. Back on the main window, click on the large Simulate

button that is located just above the left (flowsheet listing) panel and

press the Start button once this window opens to run the simulation.

Now navigate to the Configurable Equipment Manager. You will then

be able to see any resultant changes to the output parameters

associated with the equipment items of interest. In this case it is just

the power consumption parameter that we have set up for

observation. You should see that this will have increased from around

4395 kW to 5705 kW.

Step 8 The overview may be printed directly from the dialog box, but it is also

possible to copy the overview to the clipboard for pasting into Word,

or export the overview into Excel using the Export function ( ).

Using these buttons a single overview may be exported, or if there are

multiple overviews, several can be exported at once using the ‘Export

All’ function ( ).

4.3.6 Defining Stream Data Info Blocks

Information Blocks may be added to a flowsheet to display certain information

about streams or equipment on the flowsheet itself.

Adding Stream

Information

Blocks

Step 1 Ensure the flowsheet is locked ( ), then click on the Setup Info

Blocks button ( ) on the toolbar. The Streams tab at the top of the

Define Information Blocks window is the default active tab.

Step 2 Set the Select No. Parameters value to 6. After you make this

selection, the Information Block definition table will be generated in

the area beneath the drop-downs. This table will have a cell for each

of the required parameters - 6 in this case. Initially it will just

display 'No Selection' in all of its cells.

Note that the second drop-down is for selecting the recovery basis

stream. This is only relevant where you are dealing with assay data

i.e. in a mass balancing exercise. As the current exercise does not

involve the mass balancing of assays, it is not necessary to make a

selection from this drop-down.



Selecting the

Type of Data to

Display

Step 3 Click in the top left cell to bring up the Selection Options dialog box

for choosing the data that you wish to have displayed in this cell. In

this particular cell we want to display the simulated value for the

solids flow in the streams. Select the appropriate values from the

drop down cells as shown below. Note that for the Streams Info

Blocks, the name for the selected parameter/data type is auto

generated and you do not have the option of modifying this name.

Hence the Selection Name area at the top does not have editable

fields.

Step 4 Carry out the same procedure to display the simulated value for the

volume flow figure in the top right cell of the table.

Step 5 Now repeat for the procedure for the next row down in the table,

this time selecting '% Solids (Sim)' for the left cell and 'Pulp SG

(Sim)' for the right cell. The Information Block set up should now

look like the one shown below.



Step 6 For the final row, we will display the Cum % Passing 0.15 mm in

the left cell and Cumulative % Retained on 1.18 mm the right cell,

again with both being simulated values. Click on the bottom left cell

to bring up the Selection Options dialog box once more. This time

select 'Size' from the Option 1 drop down. When you do this,

another dialog will open on which you select the size that you

require data for.

After you have selected the size required, it will appear in non-

editable form in the field to the right of the Option 1 drop down.

Step 7 From the Option 2 drop down you should now select the item 'View

As'. When you do this, another dialog box will appear on which

you can select the way in which the sizing data are expressed.

Select 'Cum % Passing' from the options presented on this dialog.

The screen grab below shows the set up during this selection

process.



Your selection here will then appear in the right hand cell next to

Option 2.

Step 8 For Option 3, select 'Simulated'. The set up just before you press the

OK button should look like the one below.

Step 9 Set up the lower right cell in a similar fashion, but this time select

1.18 mm from the Size drop-down at Option 1, Cum. % Passing

from the View As drop-down at Option 2 and once more 'Simulated'

at Option 3.

Step 10 You are now ready to specify which of the streams on your

flowsheet are to have these info blocks associated with them. You

can select streams from the available streams list on the left of the

Define Information Blocks window. To do this you can use the Ctrl

or Shift key with a left mouse click to select either individual

streams or a continuous group of streams, respectively. In the

illustration below we have just selected the feed and the two

cyclone products to have info blocks on this flowsheet. Once you

have made the selection, click on the Add Info Blocks button to place



them on the flowsheet.

Note that there is also an Update Info Blocks button. If you make

changes to the info blocks definition, pressing this button will

apply the changes to any info blocks already on your flowsheet. If

you make changes to the definition table and then just press the Add

Info Blocks button, the program will place the new info block but

will also update existing info blocks as well as the contents of the

key in the top left corner.

Step 11 You can now close the Define Information Blocks window. This

will return you to the main window where you may find that you

will need to move and/or resize the key so that the text is readable.

To do this you will need to unlock the flowsheet first. Remember to

lock it again before continuing. Note that you can re-size and move

the Stream Info Blocks themselves, without first unlocking the

flowsheet.

The flowsheet should now look similar to the one below, shown in

the process of expanding the size of the key.



4.3.7 Defining Equipment Info Blocks

As well as Stream Info Blocks you can also define Equipment Info Blocks to

display information about equipment items on your flowsheet. In this exercise

we will add info blocks to the ball mill and the cyclone in the Learner Project.

Step 1 Again ensure that the flowsheet is locked ( ) before clicking on

the Setup Info Blocks toolbar button ( ). The Streams tab at the

top of the Define Information Blocks window will be active by

default. Now click on the Equipment tab to enter the environment for

defining this type of info block. Select 'Ball Mill' from the Select

Equipment list on the left and then select 2 from the Select No.

Parameters drop down on the right.

Step 2 After you have selected the 2 from this list, default parameter names

will appear under Ball Mill - Parameter 0 and Parameter 1. You now



need to define these parameters. So first click on Parameter 0 and a

dialog box will appear where you can select from the various

options available. From the Tab drop down, select 'Scaling' and

from the Parameter drop down select 'Fraction Critical Speed'. On

this dialog you need to write in your own name for the parameter

you have selected. This is entered into the Parameter Name field.

This can be exactly as it appears in the list or your own abbreviation

of this.

Step 3 When you press close on this dialog, a further selection dialog will

appear where you have a choice in this case of displaying either the

simulated or original data. One would normally select simulated

data to be displayed. Click on this check box.

Step 4 When you close this dialog by clicking the apply button, you will

see that 'Parameter 0' will have been replaced by the text you entered

for the fraction of critical speed parameter. Now carry out the same



procedure for the 'Parameter 1', this time selecting 'Load Fraction' as

the parameter. You should end up with the Define Information

Blocks window looking like the screen grab below.

Step 5 Click on the Add Info Block button and this info block will be placed

on your flowsheet, somewhere in the proximity of the ball mill. We

will now add another Equipment Info Block, this time for the

cyclone. The procedure will be much the same. First select Cyclone

from the list of equipment on the left. In this case we will only select

the one parameter to display. You will again see that by default this

will be called Parameter 0 in the definition table.

Step 6 Again click on the Parameter 0 place holder to assign an actual

parameter for this display location. In this case we will select

'Performance Data' from the Tab drop down and then Operating

Pressure, KPa (mm) from the Parameter drop down. Once more you

may need to type in your own abbreviation of the parameter name.



After you close this another will open where you select the type of

data that you wish to display for this parameter. In this case we will

assume that only the calculated data type is to be shown. Note that

you can only make a single selection here. Therefore if you wanted

to show say the SD for this parameter as well, you would have to

select 2 parameters for display from the initial drop down, then go

through the same selections until the final data type selection.

Step 7 Tick the Calculated check box and then click on the Apply button.

When you close this dialog, the dialog for selecting the parameter

will also close and you will see the parameter you have defined now

shown in the information block table.

Step 8 Now click on the Add Info Block button and this will place an

Equipment Info Block in close proximity to the cyclone. This info

block will be displaying the calculated D50 value for this cyclone.

You can now close the Define Information Blocks window and the

flowsheet should look something like the one below.



Note that you can change the size and location of the Equipment

Info Blocks as well as the Stream Data Info Blocks without having

to unlock the flowsheet first.

4.4 Summary

By working through the topics under Learning JKSimMet, you should now

have learnt how to:

Create a completely new project and complete all the steps to simulate

a flowsheet.

Display the results of simulations and export them to Excel.

Make changes to an existing flowsheet and re-simulate after the

changes have been made.

Thus if you have worked carefully through the manual to this point, you

should now have the ability to perform all the basic techniques necessary to

use JKSimMet and obtain useful results. The section that follows (Using

JKSimMet) provides a mechanism for referring to and revising any of the skills

learned up to this point.

Part

V


Using JKSimMet 131

5 Using JKSimMet

Contents of This

Section

This section covers all the basic operational features of JKSimMet. While the

previous section (Learning JKSimMet) was structured as a tutorial, this

section is structured more as a reference guide to facilitate revision and

consolidation of the knowledge gained so far .

The first chapter in this section is entitled JKSimMet Description and

contains an overview of JKSimMet. Following this there is a topic containing

some Definitions of Key Terms . In the sections that follow there are

descriptions of how the program interfaces with the user; the Menus and

Toolbars and the various Types of Windows used to display

information.

After this there are chapters that cover Building and Manipulating a Circuit

Flowsheet and then on Editing the Flowsheet Data . Finally there are

chapters on Using Simulation , Viewing Summaries of Stream Data

and on Using the Reporting Feature .

5.1 JKSimMet Description

About the

Package

JKSimMet is a software package for simulating mineral processing operations,

particularly comminution and classification. It is based on more than 25 years

of modelling and simulation research and development at the Julius

Kruttschnitt Mineral Research Centre. The package has specifically been

designed for engineers who are familiar with plant operation, but are not

necessarily skilled in modelling and computing.

JKSimMet helps the user perform the following tasks:

specify the flowsheet and equipment types

select the necessary process models

specify circuit data such as stream size distributions, equipment

dimensions and so on

tune the models (using plant data) to emulate a particular operation

use the models to simulate a circuit and predict the circuit

performance

present the results as annotated flowsheets, tables and graphs -- on

the screen or as printed reports

mass balance and adjust plant data .

What JKSimMet

Can Do

JKSimMet allows metallurgists to:

perform analysis and optimisation of the performance of existing

operations using actual circuit data

pursue flowsheet design studies for new circuits

mass balance and adjust data for circuit audit and metallurgical

accounting

run a simulation of the plant.

assess the impact on metallurgical performance of various circuit

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changes.

present the data and results on the screen, copy the data to the

clipboard or export results to MS Excel for printing and further

analysis.

Version 6 of JKSimMet is a user-friendly system that uses the Windows

interface, with features such as switching between applications, export of

data via copy and paste functions and drop-down menus for quick editing

and data manipulation.

5.1.1 JKSimMet Model Types

Process

Models

JKSimMet performs steady state simulation of a range of flotation circuit

operations. There are eight distinct types of equipment models available in

JKSimMet:

The Models

Type of Model Example Icon

Feed Feed

Water Feeder

Crusher Jaw Crusher

Gyratory Crusher

Cone Crusher

Roll Crusher

VSI

HPGR

Degradation

Mills Autogenous Mill

Rod Mill

Ball Mill

Screens Trommel

Single Deck Screen

DSM Screen

Double Deck Screen(one under)

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Using JKSimMet 133

Classifiers Air Classifier

Hydrocyclone

Spiral Classifier

Rake Classifier

O-Sepa Classifier

Splitters 2 Product Splitter

3 Product Splitter

Storage / Transport Bin

Pump

Pump Sump

Sump

Stockpile

Thickener

Final Product

Separators Flotation Cell

Flotation Column

Spiral Separator

2 Product Separator

3 Product Separator

There is also the facility to add new equipment models via offline compilation

(contact JKTech for more information).

Model

Descriptions

The equipment may be combined in both simple and complex flowsheet circuits

to enable the user to simulate the operations of plants or subsections of plants.

Simulation outcomes will be dependent on the selection of appropriate process

models (mathematical models) for the equipment items in your flowsheet.

Further control is exercised through the specification of scale for the various

equipment items, the selection of model parameter values and through the

operating data inputs such as the feed stream properties.

The algorithms for each model are outlined in under the Model Descriptions 294



section.

5.1.2 JKSimMet Capabilities

Simulation

Capabilities

In addition to the simulation capabilities discussed above, JKSimMet

encompasses all the functions necessary for the user to use and maintain a

number of flowsheets within a single project.

JKSimMet provides process engineers and metallurgists with a powerful tool

for conceptual design, tuning and monitoring of process plants and their

elemental circuits and equipment. It enables an almost infinite number and

variety of circuit designs to be simulated so that the optimal design for the

task and for the expected range of variation of input and flow conditions may

be estimated before expensive experiments with the real plant are undertaken.

JKSimMet for

Metallurgists

JKSimMet allows metallurgists to assess the impact on metallurgical

performance of:

Plant throughput

Equipment operating conditions

Equipment volume

Circuit layout

Stream destination

New equipment addition

Change in plant feed sizing, floatability or mineralogy

JKSimMet for

Plant Operators

JKSimMet also has the capability of assisting Plant Operators to understand

the effects of day to day changes in circuit operation (e.g. equipment operating

conditions, plant throughput, feed properties) on metallurgical performance.

However, JKSimMet does not and cannot replace the process engineer. It

facilitates the simulation of circuit and plant designs; it does not design. Like

any tool, the quality of the results that it produces is directly related to the skill

of the artisan who uses it.

Size Distribution There is a maximum of 40 size fractions in the size distribution for any one

stream.

Number of

Flowsheets

There is no defined limit to the number of flowsheets which may be included

in a project. However, the database will become very large and may cause a

decrease in machine performance.

Model Fitting

Constraints

In SimMet a user is only able to simulate one flowsheet at a time. There are no

restrictions on the number of parameters that can be fitted.

Number and

Type of Models

The user cannot add new models without assistance. However, JKTech

welcomes suggested new models which will be considered for subsequent

releases of JKSimMet. JKTech can also develop custom models for an

individual client.

Mass Balancing The updated SimMet mass balance algorithm allows the user to balance any

realistic circuit, provided that they follow the correct mass balance process.


Using JKSimMet 135

5.1.3 JKSimMet Constraints

System

Constraints

While JKSimMet is a powerful and flexible system there are, necessarily, some

constraints. These are:

Number of Flowsheets There is no defined limit to the number of

flowsheets that may be included in a project.

However, the database will become very large

and may cause a decrease in machine

performance.

Number of Equipment

Units per Flowsheet

The maximum number of equipment units

that can be put into a single flowsheet is

limited only by the available space on the

flowsheet screen. If large numbers of

equipment units are added, then the drawn

circuit requirements may initially exceed the

flowsheet window area available. However, a

Zoom to Fit button ( ) is provided and will

re-size your flowsheet so that it fits neatly into

the current size of the flowsheet window.

Number of Streams

Connected to Equipment

Although the flowsheet allows an infinite

number of feed streams to be connected to an

equipment unit, the simulation engine only

recognises the first 50 streams entering an

equipment unit.

Property: Size There is no limit to the number of size classes

that can be defined.

Number and Type of

Models

For a list of the available models refer to

Section JKSimMet Model Types . JKTech

welcomes suggestions for new models. Such

suggestions would be considered for

subsequent releases of JKSimMet. JKTech can

also develop custom models for an individual

client.

5.1.4 JKSimMet Expandability

Package

Expandability

JKSimMet is a self-contained package providing within itself all the features

required to build, execute and maintain a library of projects.

JKSimMet is supplied with process models for the equipment listed under the

heading JKSimMet Model Types . While these models cover many of the

typical processes encountered in comminution plants, JKSimMet has been

designed to facilitate the incorporation of new models. While the user cannot

add new models to the system, recommendations to JKTech will be considered

for inclusion in later releases. Custom designed versions of JKSimMet may

also be considered; contact JKTech for more information.

5.1.5 Definition of Terms Used in JKSimMet

A number of the terms and names used within the JKSimMet system have a

specific meaning, which it is important to understand. These terms are

132

132



defined here to avoid ambiguity.

Project JKSimMet is organized and based upon the concept of a project. A project can

be considered as a portfolio in which the user stores one or more flowsheets

and their related data.

Process Circuit A process circuit is a diagram containing a set of Equipment items

interconnected by Streams, which has been drawn in a JKSimMet Flowsheet

window to represent a particular sequence of processing steps. To be

complete, a circuit must always have at least one Feed unit and at least one

Final Product unit.

Flowsheet A flowsheet consists of one or many process circuits and their related data.

The flowsheet may contain one item of equipment or many. It can contain one

complex multi-stage circuit or many circuits in parallel. While multiple

circuits are acceptable within one flowsheet, there is no facility for linking

circuits from separate flowsheets within a project.

A user may create a project to model several flowsheets, such as a crusher

circuit and a grinding circuit. Simulation would be executed for the crushing

circuit first to a defined convergence, using the equipment data and

configuration supplied. The data resulting from the execution of this

simulation could then be manually passed as input to the grinding circuit

and simulation executed through this circuit to convergence. For both circuits

to be simulated at the same time however, the circuits must be contained

within one flowsheet, which is probably the more sensible approach in this

situation.

When you are comparing two alternative flowsheets, you can first prepare one

of them fully, including the input of the feed data. Then you can create a clone

of this flowsheet, with the clone becoming your starting point for creating the

alternative flowsheet. More detail on this approach is covered under the topic

Creating a New Flowsheet .

Equipment Process equipment items are components of the circuit. Each equipment item

consists of:

an icon on the flowsheet diagram

a data window that details the process model and associated model

parameters.

Streams Streams provide the mechanism for the flow of material between equipment

items. The streams can be named by the user and each stream contains the

simulated stream data after simulation. The stream data for the feed stream is

entered into the Feeder equipment rather than directly into the feed stream.

As well as the components outlined above, it is important to understand some

concepts relating to properties and the way these are defined in JKSimMet.

These concepts are described below.

System

Properties

There are two default system properties available for selection in JKSimMet:

Miscellaneous

Elements

There is also the capacity for the user to define their own properties.

180


Using JKSimMet 137

Classes of

System

Properties

Each of the system properties has one or more classes. The user can define as

many classes of the elements property as desired but is unable to define extra

miscellaneous value properties.

When adding or altering an element the user can change the characteristic

label and units value selected for the element; choosing either a percentage

representation or grams per ton representation. While the user cannot add to

or change the label of the miscellaneous values, they are able to change the

values assigned to them.

These settings are global characteristics that are not changed during

simulation.

Sieve Series A sieve series represents the series of gauges used to filter material in the

process circuit. JKSimMet allows the user to add as many sieve series as they

require to each flowsheet in a project. Each series may contain up to 40 size

fractions and once defined, the user is able to assign a particular sieve to

individual streams.

Ports Each equipment unit has one input port and up to three output ports,

depending on the type of equipment. Only one connector can be attached to

each output port. For the models in JKSimMet the stream characteristics of

interest are density, size distribution and solids and liquid flow rates.

5.2 The JKSimMet Menus and Toolbars

JKSimMet V6 has been developed to run under the MS Windows 7/Vista/

XP(SP3) operating systems and makes use of the Windows interface to provide

easy and flexible access to the large amount of data stored in the JKSimMet

software. A typical JKSimMet screen is shown below with various components

of the screen labeled.

A Typical JKSimMet6 Window - Showing the Main Features

The various components of the JKSimMet menus and toolbars are described in

detail in the remainder of this section.

Version 6.0.1 - March 2014The JKSimMet Menus and Toolbars


5.2.1 The Main JKSimMet Menu

The main menu of the JKSimMet interface follows a standard Windows menu

layout, with a selection of drop-down menus that allow the user to access a

range of commands. Each drop-down menu is accessed by clicking on the

appropriate word on the Menu bar.

Menu bar

The flowsheet symbol ( ) at the left-hand end of the Main menu provides a

drop-down menu for options relating to the flowsheet window; these options

are discussed below.

The other Main menu items are dealt with in the topics that follow. You can

safely move to the next topic if you wish to skip the remainder of this

discussion on the flowsheet symbol menu items.

When you click on the flowsheet symbol, you get the drop-down menu pictured

below.

Restore Clicking on the Restore item changes the Flowsheet window from its default

maximized state into a re-sizeable window within the flowsheet area. When

you do this, the flowsheet symbol ( ) will disappear from the left-hand end of

the Main menu and will now be located at the left-hand end of the new re-

sizeable Flowsheet window. Note that with a mouse you can always carry out

the restore function using the Restore button, which is the middle of the three

buttons at the right-hand end of the Main menu - see below.

Move and Size The items Move and Size are de-activated in the drop-down menu that appears

when you click on the flowsheet symbol on the Main menu. This is because

when the Flowsheet window is maximized it cannot be moved or sized until

after you have pressed Restore to make it a re-sizable window. These two items

are therefore only activated when you click the same symbol on the re-sizeable

Flowsheet window. The resizing or moving of a window is generally best

achieved by using your mouse. However, these commands are there as an

alternative by which you can achieve the same result without the mouse. If you

click on Move, you can then move the window using the keyboard arrow keys. If

139

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Using JKSimMet 139

you click on Size, you can use the arrow keys to change the size of the window.

In this case if you initially press the right arrow key, the change in size will be

achieved by movements of the right edge. Conversely initially pressing the left

arrow key will adjust the left edge. The same principle applies to the up and

down arrows and associated changes to the vertical dimension of the window.

Minimize and

Maximize

Minimize and Maximize items are also present on this menu, their activation

status depending on the current status of the window. Minimize reduces the

Flowsheet window to a bar at the bottom of the flowsheet area while Maximize

will resize the Flowsheet window to fill the available space. Both of these

functions are available to mouse users from the buttons at the end of the header

bar of the re-sizeable window.

Close The second last item on the menu is Close. While this can be used to close the

active Flowsheet, opening a different Flowsheet (the most likely reason to close

an active Flowsheet) will automatically close the active Flowsheet.

Next The item on this menu labeled Next is currently non-functional in this version

of JKSimMet.

5.2.2 The File Menu and Main Toolbar

The File Menu Clicking on the File menu item brings up a list of options relating to the

opening, saving and creating of JKSimMet files. It also includes a list of the

most recently opened files to provide you with quicker access to projects that

you may be working on through a number of sessions. The File menu plus a

brief explanation of the items, is shown below.

New Project ( ) - opens the New Project window so that the user

can create and name a new project.

Open Project ( ) - opens the Open Project window so that the user



can select an existing project to load from a list.

Some further information on the above two items is available under the

Session Window topic.

Save Project ( ) - saves the project, including all the data

associated with the equipment and streams of each flowsheet, as a

JKSimMet data file (.jksf6 extension).

Save Project As - allows the user to save the current project under a

new name.

Print ( ) - prints only the flowsheet section of the session window.

Selecting this option opens the Print window to enable the printer

properties to be selected and the flowsheet to be printed.

Exit - closes JKSimMet. The user is prompted to save the current

project if the project has not been saved after the most recent changes

were made.

Main Toolbar

Many of the functions that are available in the File menu can be accessed via

the icon buttons on the Main Toolbar.

Note that, if required, this toolbar can be moved to a more convenient place on

the screen by clicking and dragging it. When in this state the shape of the

toolbar can be adjusted to personal preference by dragging the edge.

The first three buttons on the Main toolbar provide shortcuts to the standard

New Project, Open Project and Save Project options. The next two buttons are

the copy and paste buttons.

The final button is the Help button. Click on this button to access the

comprehensive JKSimMet help system.

5.2.3 The Edit Menu

Clicking on the Edit menu item brings up a list of options relating to flowsheet

editing functions and the setting of default and/or global characteristics for

various flowsheet items. A screen capture of the Edit menu is shown below,

followed by a brief explanation of each of the menu items.

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Using JKSimMet 141

Undo - reverses the last editing change. You can continue clicking on

this to reverse a whole sequence of editing changes if required.

Redo - this reverses the action taken when the Undo button was last

pressed. Note that it is only available immediately after the Undo

button was pressed. If you carry out another editing action after

pressing Undo, then the Redo will no longer be available. Note also

that it can store a whole sequence of Undo events for potential

reversal, but only as far back as such events have been uninterrupted

by normal flowsheet editing.

Cut ( )- removes the selected item from its original location and

places it on the clipboard, ready for pasting elsewhere.

Copy ( ) - leaves the selected item in its original location and puts a

copy on the clipboard, which is then available for pasting elsewhere.

Paste ( ) - this has the normal paste functionality - places the

clipboard contents into the current cursor location.

Delete - this completely removes the selected item.

Select All - this selects all of the items on the current flowsheet.

Default Equipment Properties - this controls the default auto label

settings for any new equipment.

Default Stream Properties - this controls various features of any new

streams added to the flowsheet, including the line width and colour,

the type and size of arrowheads and the auto label positions. You can

also elect to have new streams either always orthogonal or else free

with respect to drawing direction. In addition you can change the



colour coding if you wish, for the major, minor and missing stream

categories (relevant only for mass balancing).

Default Text Properties - you can set the characteristics of any new

text that is placed on your flowsheet, including all stream and

equipment labels.

Default Drawing Object Properties - here you can change the default

appearance of any further drawing objects added to the flowsheet -

including line colour, fill colour,

Equipment Auto Label Properties - the dialog box that opens when

you click on this item allows you to control the colour and thickness of

the equipment label outlines, the fill pattern and colour as well as the

font characteristics of the text within the labels. Note that any changes

made here affect all of the existing equipment labels, not just ones that

are added after the setting has been changed.

Stream Auto Label Properties - this provides the same controls over

the appearance of the Stream Auto Labels as was described above for

the Equipment Auto Labels.

Port Properties - here you can (if you wish), change the colour of the

ports. There are two tabs, the first is for the product ports and the

second is for the feed ports. Pattern selection is also possible, but not

really practical in this case since the ports are too small for a pattern to

be visible.

Flowsheet Settings - this menu item allows you to change the

background colour of the flowsheet and the page dimensions and

orientation. It also provides the option to toggle the display of the

icons in the software between JKSimMet5 icons and JKSimMet icons

as well as allowing the user to choose the number of significant

figures displayed in the information blocks. Note that zooming out

will better allow you to appreciate how your flowsheet is structured

relative to the size and shape of the paper you have chosen for

printing. You can also get to this item from the menu that appears

when you right-click on your flowsheet.

Properties ( ) - This menu item allows the user to view and alter

the properties of a selected stream or equipment item on the flowsheet.

Here the user can alter the name, label position, line style and fill style

of the selected item.


Using JKSimMet 143

5.2.4 The View Menu

View Menu

The View command on the Main JKSimMet Menu controls which of the

available flowsheet features are visible in the session window. Some of the

items on this menu are also available via toolbars, but others are only

available from this menu. The items on this menu are listed and explained

below, in the order that they appear on the menu.

Toolbar - when checked, the main JKSimMet toolbar is visible.

Status Bar - is visible at the bottom of the JKSimMet session window

when checked.

Workspace - this refers to the list of flowsheets contained in your

project, which normally appears as the left-most panel of the session

window. This panel will disappear if the Workspace item is

unchecked. This may be useful if you have a large flowsheet and need

more space to accommodate it.

Grid - this toggles the visible grid on or off. Note that snapping to the

grid is still possible, even when you have switched the grid to "off" so

that it is no longer visible.

Snap to Grid - this determines whether the items on your flowsheet

will snap to the grid when they are moved. This setting provides a

convenient tool for aligning the items on your flowsheet.



Angle Snap - this applies to rotation of equipment items; when

switched off, any angular position is possible whereas when

switched on, the only angular positions possible are those in which

the corners of the equipment item line up with the grid.

Grid Properties - this allows adjustment of the grid spacing and other

properties via the Grid Properties windows, shown below.

Vertical Rulers - this is a toggle for turning on or off, the vertical ruler

along the side of your flowsheet. Note that it only applies to the

flowsheet that is currently active.

Horizontal Ruler - similarly, this toggles on and off the horizontal

ruler at the top of your flowsheet. Again, it only effects the appearance

of the currently active flowsheet.

Ruler Properties - this brings up a dialog box in which you can select

the colour and width of the rulers plus the colour of the ruler tracking

line that appears within the rulers to indicate the current cursor

position.

Equipment Auto Labels ( ) - this toggles on and off, the equipment

auto labels.

Stream Auto Labels ( ) - likewise, this toggles on and off, the


Using JKSimMet 145

stream auto labels.

Note that both the Equipment and Stream Auto Labels can be also

switched on or off via buttons on the Flowsheet toolbar.

Port ( )- via this item you can control whether or not the ports are

to be visible on your equipment items. It is very useful to have these

switched on at least while you are constructing the flowsheet. After

this, it is a matter of preference as to whether you have the ports

highlighted or not. This toggle is also available via a button on the

Flowsheet toolbar.

Redraw ( ) - this is sometimes needed if you have a large flowsheet

to which you have just made changes and immediately after making

them you find that the computer is not rendering them properly.

Clicking on Redraw will normally remedy this type of problem.

Zoom Normal - this zooms back to the normal level after you have

used the other zoom functions to move away from this zoom level.

Zoom Percent - this allows the user to select the zoom percent from the

options 50%, 75%, 100% (normal) and 200%.

Zoom Custom - with the Custom Zoom you can either select one of the

above from the drop-down or you can type in any percent value from

50 to 500.

Zoom to Fit ( ) - this is a convenient way to get the whole of your

flowsheet to fit neatly into the available window size. Note that there

is a button on the Flowsheet toolbar that also achieves this result.

Zoom to Selection ( ) - if you have selected part of your flowsheet

for closer inspection, this command will zoom to the point where the

selected part of the flowsheet just fits into the available window size.

Again note that on the Flowsheet toolbar there is a button for this

function also.

5.2.5 The Flowsheet Menu and Toolbar

The Flowsheet

Menu

The drop-down menu that is triggered when you click on the Flowsheet item of

the main JKSimMet Menu bar, is shown below.



This menu allows an alternative route into most of the functionality provided

via the Flowsheet toolbar (see below). There are some differences however.

The Run Model Fitting item on this menu is not on the Flowsheet toolbar, but is

located on the separate Model Fit toolbar.

The Flowsheet

Toolbar

If required, the Flowsheet toolbar can be moved to a more convenient place on

the screen by simply clicking and dragging it. Once moved to a floating toolbar

position, the shape of the toolbar can be adjusted to your personal preference by

dragging the edges. This applies to all the other toolbars as well.

Below is a screen-grab of the Flowsheet toolbar, followed by a listing of all the

buttons it contains with explanations of their functions:

Lock The Lock button controls access to the various other functions on the Flowsheet

toolbar.

When unlocked, access is available for making changes to the flowsheet's design

and layout, including the addition or subtraction of equipment and streams,

changes to the locations of equipment items and to the routes taken by

connecting streams. In addition all properties associated with the appearance of


Using JKSimMet 147

all flowsheet components can be accessed when this button is in the unlocked

position.

When this button is in the locked position, none of the above functionality is

available. Instead, the System Properties, Sieve Series, Survey Data, Configurable

Equipment Manager, Run Simulation, Configurable Stream Overview,

Simulation Manager, Run Balance, Equipment, Stream, Reporting, Config Graph

and Setup Info Blocks buttons now become accessible. In fact the flowsheet must

be locked before any changes can be made to the data. Requiring that the

flowsheet be locked for data entry ensures that items are not accidentally moved

when you are trying to access the data.

Select The Select button is normally activated by default when you first open a project.

It will be de-activated however when you press the Zoom button ( ) and you

will then need to re-activate it before you can select any items on your flowsheet.

When the Select button is active, the cursor will turn back to the normal selection

cursor ( ). This may look different to the illustration here, as it will depend on

the cursor option settings on your computer. With the Select button activated

you can click on any individual equipment item, stream or label on your

flowsheet to select it. This is the case regardless of whether the flowsheet is

locked or unlocked. The locking status just affects what you can do with the

items once they have been selected. Note that you can select multiple items by

holding down the left mouse button and dragging the mouse until the dotted

line encloses all the items you wish to select. Letting go of the left-button will

then select these items. You can also select any number of individual items by

holding down the Control key and clicking the mouse as the cursor moves over

each of them.

Zoom When you click on the Zoom button, the Select button will be switched off and

the cursor will change to a zoom cursor ( ) to indicate that the zoom function

is now active.

When this cursor appears on your flowsheet, you can hold down the left-button

and drag your mouse to outline the area you wish to zoom into. When you let go

of the mouse button, the area you have outlined will be expanded to occupy the

whole of the current flowsheet window.

Also when you have the Zoom button activated, clicking on the left mouse

button will increase the degree of zoom by a set increment and clicking on the

right button will decrease it by the same amount.

To turn off the zoom facility, click again on the Select button ( ).

Zoom to

Fit

Clicking on the Zoom to Fit button will zoom in or out sufficiently to just

accommodate the whole of your flowsheet. This is usually the best way to zoom

back out again after you have zoomed in to a particular region of the flowsheet.

Zoom to

Selection

For the Zoom to Selection button to be available, you first need to have selected

some items on your flowsheet. When you click on this button, the program will

zoom in or out as needed, so as to just include all of your selected items within

the boundary of the visible flowsheet.



Auto Labels

for

Equipment

and Streams

The Equipment Auto Labels and Stream Auto Labels buttons are used to add

labels to the equipment and streams on the flowsheet; the labels become a part of

the equipment and streams and move when the equipment or stream is moved.

To change the default label, double-click on the equipment and type in the new

name, see chapter on Annotating the Flowsheet .

Clicking on the Equipment Auto Labels button or the Stream Auto Labels button

toggles between having the labels for this flowsheet either displayed or not

displayed. Note that these buttons can be operated irrespective of the flowsheet

locking status.

As noted above, in the menu system these two functions are available via the

View menu rather than the Flowsheet menu.

Ports This button acts as a toggle for switching on and off the display of the ports for

each of the equipment item. Feed ports are represented by blue dots and product

ports by red dots. This facility is normally turned on by default. Note that the

position of this switch does not affect functionality. You can still connect

streams to ports, even when they are not displayed. However for icons with

vertical axis symmetry, such as the one used for flotation cells, you can't easily

tell which side is the feed port until you turn on the ports display. Thus it is

usually better to have ports switched on, especially while the flowsheet is being

constructed.

Redraw The Redraw button is used to refresh the screen. This is particularly useful after

equipment has been repositioned.

If you have made changes that are not yet appearing on your flowsheet, click on

the re-draw button and the whole flowsheet will be redrawn. It should then

include all of your modifications.

System

Properties

The System Properties button opens the System Properties Window , where

the user can add Elements to the system and alter the miscellaneous properties.

Sieve

Series

The Sieve Series button opens the Sieve Series Window . It is in this window

that the user can add and remove sieve series, as well as assign them to

individual streams.

Survey

Data

The Survey Data button opens the Survey Data window . This allows the user

to input and transfer survey data into the streams, overwriting any existing

experimental data.

Configurabl

e Equipment

Manager

The Configurable Equipment Manager button brings the Configurable Equipment

Manager Window into view. This window allows the user to create an

overview to view and if necessary alter the settings for the different models used

in the current flowsheet.

Run

Simulation

Clicking on the Run Simulation button opens the Run Simulation window,

which allows the user to select the equipment and streams to simulated, set the

simulation settings and run simulations.

Configurabl

e Stream

Overview

The Configurable Stream Overview window is accessed by clicking on this

button. This feature allows the user to create one or more summary tables of

selected stream data after simulation of the flowsheet. The data in the table can

then be printed, copied to the clipboard or exported to MS Excel.

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Simulation

Manager

The Simulation Manager allows multiple simulations to be performed in a

batch operation. The user can set a range of key operating parameters in the

simulations and record the key performance indicators for each simulation

performed.

Run

Balance

The Run Balance button brings the Input/View Mass Balance window into

view. This window allows the user to select the streams, equipment, elements

and sizes to include in the balance and control the scope of the fitting.

Equipment

The Equipment button brings the Equipment Window into view. A drop-

down list in the Equipment window displays all of the equipment on the current

flowsheet. The Equipment window allows the user to select the model to be used

for the equipment via a drop-down list, and to input the parameters for the

chosen model. The Equipment window also shows the feed and product streams

from the equipment; the Stream window for each of these streams can also be

accessed from the Equipment window.

Stream Clicking on the Stream button opens the Stream Window from which the

user can view the stream data after simulation.

Reporting

The Reporting button opens the Reporting to Excel dialog. This allows the

user to configure one or more reports by listing which stream and equipment

data are to be exported to an Excel workbook for further analysis and printing.

Configurabl

e Graphing

The Config Graph button opens the Configurable Graphing Window . Here

the user can create one or more graphs to view the data held in the streams and

equipment on the current flowsheet.

Setup

Info Blocks

The Setup Info Blocks button is used to set up both Equipment and Stream Data

Info Blocks . These are configurable information blocks that can be attached to

selected equipment items and streams. They are used to provide a convenient

flowsheet based readout of the results and the settings of your simulations.

5.2.6 The Balance, Fitting and Simulate Toolbar

Toolbar for

Main

JKSimMet

Functions

The Balance, Fitting and Simulate toolbar is located in the left side panel, just

above flowsheet list.

Run Balance

The Run Balance button brings the Input/View Mass Balance window

into view. This window allows the user to select the streams, equipment,

elements and sizes to include in the balance and control the scope of the

balancing process.

Run Model

Fitting

The Run Model Fitting button opens the window for model fitting , where

the user can tailor the process models associated with the various equipment

items in their flowsheet, to their individual treatment characteristics based on

the data that has been gathered for this circuit.

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Run

Simulation

Clicking on the Run Simulation button opens the Run Simulation window,

which allows the user to select the equipment and streams to simulated, set

the simulation settings and run simulations.

5.2.7 Drawing Toolbar

The Drawing toolbar contains buttons for all the commands associated with the

preparation of your flowsheet. A screen grab of this toolbar is shown below.

Note that these buttons are all de-activated once the flowsheet has been locked.

The functions of the various buttons on this toolbar, going from left to right, are

described below.

Properties The Properties button gives you access to the properties dialog box for the

currently selected flowsheet item or items. Properties in this context refers to the

properties of the icon itself, not the properties of the physical equipment that it is

representing. The later properties are associated with modelling of the

equipment and are only available once the flowsheet has been locked.

Line This button simply allows you to draw a line on your flowsheet. When click on

the button and move the cursor down to the flowsheet, you will see that the

cursor now takes the form of a cross ( ). Click the left mouse button and drag in

any direction to create the line. Let go when it is at the desired length. If you hold

down the Shift key while you are dragging, the line will then snap to the grid

and will be either horizontal or vertical, depending on which direction you are

moving your mouse.

Rectangle When you click on this button, you will again note that the cursor takes the form

of a cross once the mouse is positioned over the flowsheet. Click the left button

and drag in the direction of the diagonal of the proposed new rectangle. The

proposed rectangle will be outlined by a dashed line while you continue to hold

down the mouse button. Once you let go of the button, the new rectangle will be

placed on the flowsheet and its perimeter will change to a solid line.

Text Clicking on this button followed by clicking on the active flowsheet will add a

resizable, editable text box to the flowsheet.

Image When you click on this button you will be presented with a file open type dialog

box, where you will be able to select the directory where your images are stored.

Click on the image file you require and then on the Open button.

If the image you have imported initially occupies the whole of the flowsheet

panel, use the zoom buttons to zoom out. This will allow you to see the handles

around the perimeter of your image and by using these you can re-size the image

to whatever is required.

Rotate After clicking on the Rotate button, you will see that the cursor changes once

you are hovering over the selected item, to a circular arrow symbol, similar to the

image on the button itself. If you then click and drag, the item of equipment will

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Using JKSimMet 151

rotate. Let go when it has reached the orientation you require.

Rotate Left &

Right

The Rotate Left button rotates the selected item anti-clockwise by 90 degrees. The

Rotate Right button also rotates by 90 degrees, this time in the clockwise

direction. For the Rotate Left and Right commands, the rotation is occurring

about a line that is perpendicular to the plane of the computer screen.

Flip Vertical &

Horizontal

The Flip Vertical and Flip Horizontal buttons effectively rotate the object

concerned through 180 degrees, through a plane that is at right angles to the

screen. The rotation occurs about a line that passes through the centre of the

object and lies flat on the computer screen.

Align Top &

Bottom

These buttons can be used to align either the tops or the bottoms of a group of

objects that you have selected. First select the set of objects required, either by

using the Control key and clicking on the separate objects or else by dragging

the mouse to encompass the objects with the left button held down. Then click

on whichever of the buttons is appropriate for your purposes. Note that the

alignment will be to the top (or bottom) of the last selected item. You can see

which item was last selected as it will have grey rather than open selection

indicator squares around its perimeter.

Align Middle

& Centre

To align either the horizontal or vertical centre lines of a number of objects, you

again need to first select the set of objects for alignment (see above). Then just

click on the appropriate button for middle or centre alignment, as required (see

left). Again, the alignment will be to the centre line of the last selected item.

Align Left &

Right

Left and right alignment of objects is achieved by again selecting the set of

objects before clicking on whichever is required of the two buttons shown at

left.Again, the last selected object will be the one that determines the alignment

position.

Space Across

& Down

These buttons allow you to evenly space objects that you have placed on your

flowsheet. Pressing the Space Across button distributes the selected objects so

that the entire spacing between the far left object and the far right object is

divided evenly between entire row of selected objects. Note that the objects do

not necessarily have to be first lined up in the vertical direction for this

horizontal spacing function to work.

Similarly, pressing the Space Down button divides the entire vertical spacing

between your highest and lowest object so that all the selected objects will then

have equal vertical spacing between them.

Same Width,

Height or Size

Using these buttons the user can make a set of objects on a flowsheet all have the

same width, height or both. Note that the last selected object (indicated by the

grey selection handles), will be the one to which the other selected objects are

matched. Use the Same Size button when you wish to make sure that the

dimensions stay in the same ratio as they exist in your last selected object.

Nudge Up,

Down, Left

and Right

There are four Nudge buttons that allow you to make small adjustments (up,

down, right and left) to the positioning of objects on your flowsheet. First select

the object to be moved and then click on the appropriate Nudge button. These

functions are mainly useful for adjusting the positioning of equipment units

when the attached streams have gone slightly out of horizontal or vertical. You

can use it to make the small adjustments needed to return the streams to an

orthogonal arrangement.

Front and Back The Front and Back buttons can be used if you have overlapping items on your

flowsheet. Pressing one of these buttons will determine which of the



overlapping items appears to be at the front and is therefore fully visible and

which appears to be at the back and therefore partially obscured. When a Front

or Back button is pressed, the item currently selected responds by moving to the

front or back as appropriate. Note that if you have several overlapping items

selected and you press Front, then the item last selected will move to the front

and the overlap order for the other items will also mirror the selection order.

This means that for instance, the second last item selected will be just under the

last item selected, but will be over all of the other items.

5.2.8 The Tools Menu

The Tools menu on the Main JKSimMet Menu allows the user to customise

which tools and menus are displayed in the session window. Click on

Customize then there are two tabs, Toolbars and Command.

In the Toolbars tab the user can choose which toolbars appear at the top of the

JKSimMet screen. The 'look' of the toolbars can also be adjusted using the

Show Tooltips and Cool Look options. Users can also add and name new

toolbars by clicking on the New button. Once created, the new toolbar can be

populated with buttons by either moving existing buttons from other toolbars

or by moving copies of the existing buttons from the Command tab of the

dialog box into the new toolbar..

The Command tab shows all of the buttons that make up each of the existing

toolbars and the menu. Selecting one of the buttons will provide a description

of the functionality it offers in the description box at the bottom of the

window, as shown below.


Using JKSimMet 153

To customize an existing toolbar users can drag any button of their choice

from this tab onto the toolbar. While this dialog box is open users can also

remove or reposition buttons on existing toolbars, allowing a large degree of

customization.

5.2.9 The Help Menu

Help Menu

The Help menu on the Main JKSimMet Menu allows the user to access the

help files, and provides software version information:

Help ( ) - (or pressing F1) takes the user to the contents page of the Help

File.

About - gives details of the JKSimMet version number, the version numbers of

the databases and copyright information.

5.3 JKSimMet Windows

Version 6.4 of JKSimMet makes full use of the Windows interface to allow

users to view whichever data they choose on the screen at any one time by

simply opening the required windows. This section describes briefly each of

the main window types in JKSimMet.

5.3.1 Configurable Equipment Manager

The Configurable Equipment Manager window displays a summary table of

Version 6.0.1 - March 2014JKSimMet Windows


selected data for a currently selected model in the flowsheet. The user can

configure one or many tables for display in this window.

The Configurable Equipment Manager window can be opened by two methods:

1. Selecting Configurable Equipment Manager from the Flowsheet menu.

2. Clicking on the Configurable Stream Overview button.

Opening the

Configurable

Equipment

Manager

The Configurable Equipment Manager feature can only be accessed when the

flowsheet is locked.

The Configurable Equipment Manager provides a data summary for a selected

model in the flowsheet after simulation has occurred. The information

displayed in the Configurable Equipment Manager window is exactly the same

as the information displayed in the individual Model Data windows. The

advantage of the Configurable Equipment Manager is that all of the data for the

equipment items that use this model can be viewed together, rather than having

to view each equipment item in a separate window.

The summary table can be printed directly from this window, copied to the

clipboard for pasting into other programs such as Word or exported to Excel for

further analysis or graphing.

5.3.2 Config Graph Window

The Configurable Graphing window lets the user set up and view data from

streams and equipment in a graphical format.

Users can open the Configurable Graphing window via the flowsheet menu or

from the icon on the flowsheet toolbar.

Note that the Graphing feature can only be accessed when the flowsheet is

Version 6.0.1 - March 2014 JKSimMet Windows

Using JKSimMet 155

locked.

Create a New

Graph

To create a new graph click on the 'New' button, in the dialog that opens, the

user is required to give a name to the graph (or accept the default) and to

choose whether the graph will display stream or equipment data.

The user must then choose a format for the sizing data:

They then must choose which type of data the report is going to display:

They are then required to select the streams or equipment that they wish to

view:



Viewing the

Graph

The Graph tab displays the data that you have selected in the stream tab. To

alter the settings of the graph, select the Format button (highlighted).

Formatting the

Graph

The format window allows you to set the name for each axis, the range that

each axis covers and how the data is plotted and shown to the user.


Using JKSimMet 157

5.3.3 Configurable Stream Overview Window

The Configurable Stream Overview window displays a summary table of

selected data for selected streams in the flowsheet. The user can configure one or

many tables for display in this window.

The Configurable Stream Overview window can be opened by two methods:

1. Selecting Configurable Stream Overview from the Flowsheet menu.

2. Clicking on the Configurable Stream Overview button.

The Configurable Stream Overview feature can only be accessed when the


Configurable Stream Overview provides a data summary for selected streams in

the flowsheet after simulation has occurred. The information displayed in the

Configurable Stream Overview window is exactly the same as the information

displayed in the individual Stream Data windows.

The summary table can be printed directly from this window, copied to the

clipboard for pasting into other programs such as Word or exported to Excel for

further analysis or graphing. The Configurable Stream Overview window is

discussed in more detail under the heading Using the Configurable Stream

Overview .213



5.3.4 Information Blocks

Information

Blocks

Information blocks allow the user to display information about the performance

and characteristics of both streams and equipment on the flowsheet.

The Information Blocks window can be opened by two methods:

1. Selecting Info Blocks from the Flowsheet menu.

2. Clicking on the Setup Info Blocks button.

Note that the Info Blocks feature can only be accessed when the flowsheet is

locked.

Experimental or simulated data may be displayed, and the Info Blocks feature

allows the information to be displayed for as many streams or equipment units

as the user wishes. Information Blocks are discussed in more detail within

the section Building and Manipulating a Flowsheet .

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Information

Blocks Display

Once added to the flowsheet, the information blocks can be moved around and

re-sized as the user requires.

-

5.3.5 Model Windows

The Model window collects data required for the selected model calculation

and displays the equipment parameters calculated during simulation. The

Model window is accessed by clicking on the double arrow button next to the

selected model in the Equipment window. While the contents of the model

window vary depending on the models chosen, the general layout of the

model windows is common to all models; see below.



Whilst all model options for particular equipment are accessible from the

Equipment Model drop-down list, JKSimMet can only use a model in

simulation if its prerequisite stream properties have been added via the

System Properties table. An error message will be displayed during

simulation if a model has been selected for which the required stream

properties have not been chosen.

The data associated with a particular model are displayed on a series of tabs.

Most tabs have an associated drop-down list for the model option selection.

The model window consists of:

1. A title bar in which the chosen model option is displayed.

2. A series of tabs used to display or allow data entry for the chosen

model.

The data layouts for all of the model types, including details of prerequisite

stream property requirements, are detailed in the Model Descriptions

section. The Model windows are also discussed in more detail within the

chapter on Editing the Flowsheet Data.

5.3.6 Property Windows

The properties of the flowsheets, equipment, streams and labels can be

accessed in the Flowsheet, Equipment, Stream Properties and Label Properties

windows, respectively.

Flowsheet

Properties

Window

Right click on the flowsheet name and select Properties to open the Flowsheet

Properties window. This window allows the user to change the flowsheet

name, add any comments about the flowsheet and view the last modified date.

Note that there is a 50 character limit for the flowsheet name and comments

sections.

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Equipment

Properties

Window

To open the Equipment Properties window unlock the flowsheet and double-

click on the equipment item to be examined. Alternatively, you can right-click

on the equipment item and select properties from the right-click menu. The

Equipment Properties window allows the user to change the equipment name

and orientation as well as various aspects of the equipment item's physical

appearance on the flowsheet.

Stream

Properties

Window

To access the Stream Properties window for a stream, unlock the flowsheet

and double-click on the stream you wish to examine or again use the right-

click menu. This will open the Stream Properties window in which the user

can change the name of the stream as well as various other characteristics

affecting the streams physical appearance. Note that it is recommended

streams be given meaningful names, such as ‘Rougher Feed’, ‘Rougher Conc’,

‘Rougher Tail’, as this will enable them to be more easily recognized later,

when the simulation results are reviewed.



5.3.7 Reporting to Excel Window

The Reporting to Excel window allows the user to select any stream or

equipment data for export to an Excel workbook. Reporting is the main

method for exporting data from JKSimMet, with the formatted data in the

Excel workbook being available for printing and graphing as required. The

user can configure multiple reporting formats.

The Reporting window can be opened by two methods:

1. Selecting Reporting from the Flowsheet menu.

2. Clicking on the Reporting button.

Note that the Reporting to Excel feature can only be accessed when the



Using JKSimMet 163

The stream data and equipment data are exported together. Multiple report

formats can be created. The Reporting feature is discussed in more detail

under the heading Using the Reporting Feature .

5.3.8 Simulation Manager Window

The Simulation Manager window is where the user can set up multiple

simulations, which can then be run in sequence as a batch operation. The user

can configure multiple scenarios for simulation and can edit key operating data

used in the simulations, which are displayed in the tables (e.g. Feed tonnage, %

solids).

The Simulation Manager window can be opened by two methods:

1. Selecting Simulation Manager from the Flowsheet menu.

2. Clicking on the Simulation Manager button.

Note that the Simulation Manager can only be accessed when the flowsheet is

locked.

Selected results of the simulations are displayed on the stream and equipment

data tabs (labelled Results - Streams and Results - Equip), once the batch of

simulations has completed. This allows the user to readily compare simulated

results under the different operating conditions.

The simulation operating data summary and the results of the simulations

displayed on stream and equipment tabs in the window can be printed directly

from the Simulation Manager window or copied to the clipboard for pasting into

other programs such as Word or Excel. The Simulation Manager window is

discussed in more detail under the heading Simulating Using the Simulation

Manager .

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201



5.3.9 Simulation Window

Simulation

Window

The Simulation window is where a simulation of the current flowsheet settings

can be run, and the controls set for this simulation.

The Simulation window can be opened by two methods:

1. Selecting Run Simulation from the Flowsheet menu.

2. Clicking on the Run Simulation button ( ).

Note that the flowsheet must be locked before the user can select the Run

Simulation button.

The Simulation window provides the selection and configuration options for

running a simulation. Here the user may choose which simulation to run or to

create a new simulation using a different selection of equipment and streams.

The user can also configure the required convergence, the number of iterations,

the interpolation used and the starting condition of the simulation.


Using JKSimMet 165

Simulation is discussed in more detail in under the heading Using Simulation

.

5.3.10 Stream Windows

Accessing

the Stream

Data

The Streams window provides access to the Stream Data window to view the data

for each stream.

Stream

Button

The Streams window for each stream can be opened by three methods:

1. Double-clicking on a stream.

2. Selecting Stream from the Flowsheet sub menu.

3. Clicking on the Stream button.

All of the streams in the current flowsheet may be accessed from the Streams

window via the Stream Name drop-down list. The Streams window can only be

accessed when the flowsheet is locked.

The Stream Data window is accessed by clicking on the double arrow button next

to the selected stream. Once the Stream Data window is open the user can view the

stream data in a variety of ways, as required since there is considerable scope for

customising the way these data are viewed. Note that in the column displaying

simulated data, the fields will not contain values until simulation has been

completed.

199



Totals Tab The data associated with a particular stream are displayed on a series of tabs. The

tabs visible in the Stream Data window are always present. The Totals tab lists the

overall properties of the stream.

The default window shows various data types - simulated, experimental, SD, mass

balanced, error and fitted. The data types that are shown in these windows can be

controlled by the user. If you click on the Data Type View button, a dialog box will

appear where you can exercise a choice about the data types you wish to see.

Click on any of the data type headings and you will be presented with a drop-

down list containing the six available data types plus the option of selecting

"none". If you chose "none", the column concerned will be eliminated from the

Stream Data window display. If you try to select any given data type twice, you

will get an error message. If you are carrying out simulations only for instance, you

would probably want to see the Sim, Exp and Error data types and eliminate the

other three.

SD

Calculation

To the right of the Data View Type button is a button labeled "SD Calculation".

This button brings up the Automatic SD Calculation window. Note that this is only

relevant when you are carrying out mass balancing or model fitting. It is not

required for simulations.


Using JKSimMet 167

The Automatic SD Calculation window allows you to set up an SD calculation

method differently for each property within each stream. From the left panel

containing the list of streams, you can select either a single stream or a group of

streams. To make this selection you can use the Control key with a left mouse click

to pick out individual streams for the group. Alternatively, you can use the Shift

key and the left mouse button to add all the streams between the one initially

selected and the one currently under the cursor. Once the stream or streams have

been selected, you then select the property to which the SD method is to apply. This

is done via the Property drop-down at the top right of this window. You can select

All if you want this SD calculation method to apply to all properties of the selected

streams.

Having selected the streams and the properties, you then go to the SD Calculation

Option drop-down where you can now select the method of determining the SD's

for this group of streams/properties.



If you select Poor, Average, Good or Excellent, the program will use a fixed

percentage of the stream. Note that you can change the percentage however, that

applies to each of these selections, if required. The other possible selections include

"Fixed" where you can again change the value to whatever you deem to be

appropriate. But in this case keep in mind that you are selecting the actual value of

the SD rather than a percentage of the stream value. There are several other

methods that can be applied for SD calculation.

Whiten SD If you select All Sizes from the Property drop-down, then there will be an extra SD

calculation option available at the top of the list. The extra option is "Whiten" -

which is an SD calculation method that only applies to sizing data. This option is

not visible in the screen grab above because the image was generated after

selecting TPH or All from the Property drop-down. Note that Whiten is the most

commonly used SD calculation method for sizing data. To apply this to your sizing

data but still apply some other chosen method to all of your other data, you could

first select All and apply the appropriate "other method". After this you can select

All Sizes and apply Whiten, which would then leave the other method still in force

for all of the non-sizing data.

Sizing Data The other available tab contains the stream sizing data. These data will be

displayed in the format that has been selected via the buttons on the main toolbar.

The sizing data can be expressed as either % Retained ( ), Cum % Retained (

) or Cum % Passing ( ) . Note that this selection can be changed at any time,

even when this stream data window is open.


Using JKSimMet 169

Selecting

the Type of

Error

Calculation

In the case of the error column you can change the form of the error that is

displayed and the currently selected form will be shown in the column header.

This is done by clicking on the Error Sum button, which is the button second from

the right on the Stream data toolbar.

These new calculations are for display purposes only. The weighted error is used

in all Mass Balance and Model Fit calculations.

After pressing this button, the Error dialog box will appear where you can specify

both the types of data that are to be compared for determining error values and the

method by which these errors are calculated. For instance in the settings shown in

the screen grab below, the errors will be obtained by comparing the experimental

and balanced data and the method of calculation will just be a straight percentage

error calculation.



Also in this screen grab, you will notice there is a frame labelled Error Sum below

the drop-down selection boxes. Here there are radio buttons where you can select

the errors that are to contribute to the calculation of the error sum figure that is

displayed in a field (shown circled below), at the top of the Stream data window.

Note that it is only when you select Exp v Bal data for comparison that all three

options are available for the error sum calculation. Because JKSimMet does not

contain models that predict element distributions, the last two options cannot be

selected where either Fit or Sim data are one of the data types to be compared.

These options will be greyed-out in all but the Exp v Bal data case.

Error

Calculation

Methods

and

Summing of

Errors

The types of error calculation available for selection are Weighted, Percent and

Absolute. Weighted errors take account of the reliability assigned to the various

data points by dividing the difference by the SD value. Larger SD values mean that

the differences will contribute less to the total error calculation. The other two

methods take no account of the assigned SD values.

The calculation methods are:

Weighted errors are calculated as [(Exp - Bal)/SD]2

Percent errors are calculated as Abs[(Exp - Bal)/Exp] * 100

Absolute errors are calculated as just (Exp - Bal)

In the case of the first two error calculation methods, the individual errors are

always going to be positive values. Thus to obtain the error sum in these two cases,

the individual values are simply totalled.

For the Absolute error values though, there will be negative values displayed for

some data points and positive ones for others. To make these values all contribute

to the total error and do not tend to cancel each other out, in this case it has to be

the modulus of each value that gets incorporated into the Error Sum calculation.


Using JKSimMet 171

Accessing

the

Configurabl

e Graphing

Window

The Configurable Graphing window is also available via a button on this toolbar as

shown below.

Changing

the Column

Layout

You can change the column layout of the Stream data window if required. This is

achieved by clicking on the Data Type View (Dv) button - circled in the following

screen grab.

The Change Data Type View window will then open. The image below shows this

window with the user selecting None from the data type options for the last

column. This action will remove the last column once the user has returned to the

Data Type window. Note that selecting None does not delete any existing data; it

merely tidies up the display.

The Streams window also lists the equipment from which the stream originates

and the equipment to which the stream flows. Clicking on the double arrow button

next to the From Equipment and To Equipment display panels opens the Equipment

window relating to that equipment. The Equipment window is discussed

above. The Stream Data windows are discussed in more detail within the Using

Simulation chapter.

Copy Grid The copy grid button allows the user to copy the data from the active grid to the

clipboard, from where it can be pasted into other applications as required.

5.3.11 The Equipment Window

The data for the equipment can be viewed in the Equipment window.

The Equipment window can be opened by three methods:

1. Double-clicking on the equipment item itself.

2. Selecting Equipment from the Flowsheet menu.

3. Clicking on the Equipment button on the Flowsheet toolbar.

All of the equipment units in the current flowsheet may be accessed from the

Equipment window via the Equipment Name drop-down list. The Equipment

window can only be accessed when the flowsheet is locked.

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210



The equipment models available for the selected equipment unit are accessed via

the Equipment Model drop-down list. The Model window is accessed by clicking

on the double arrow button next to the selected model. The Model window is

discussed in more detail in the next topic.

The Equipment window also lists the feed and product streams of the selected

equipment. Clicking on the double arrow button next to the names of the streams

that are feeds or products from the selected equipment opens the Streams

window. The Streams window is discussed below. The Equipment and Model

windows are discussed in more detail in the chapter on Editing the

Flowsheet Data.

5.3.12 The Session Window

The session window is the driving seat of JKSimMet. In this window the user

creates the flowsheets for analysis.

After starting the JKSimMet program a blank session window appears as shown

below.

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Using JKSimMet 173

The user can create a new project or load an existing (i.e. previously saved)

project.

Create a New

Project

To create a new project click on the New Project icon on the toolbar. In the dialog

that opens, the user is prompted to name the new project and specify its path.

This loads a blank project containing a single flowsheet, automatically given the

default name of "FlowSheet1".

Now that a flowsheet exists, the equipment list is displayed between the

flowsheet list and the flowsheet display pane on the right. The procedure for



creating a flowsheet will be discussed in more detail below.

Load an

Existing

Project

Alternatively, the user can select a previously saved project from the list of

existing projects by clicking on the Open Project icon. This displays an Open

dialog which allows the user to select the project to be opened.

The title bar in the session window displays the open project and flowsheet in

the form JKSimMet - [Project Name – Flowsheet Name]. Note that the equipment

list is not available until a project has been opened or created and therefore at

least one flowsheet is present.

Resizing the

Session

Window and

the Internal

Panels

Note that the session window can be resized by moving the cursor to any edge of

the window. When it is positioned over the border line, the cursor will change

from the normal arrowhead to a thin line with an arrowhead at each end. While

the cursor is in this state, left click and drag with the mouse to change the

window size to whatever you require and release the mouse button when

finished. Note that you can drag the top, bottom, sides and the corners using this

method. When you drag a corner, both the height and width of the window can

be changed simultaneously.

The three main panels within the session window can also be resized in a

similar manner. You will see the mouse cursor turn into the double headed

arrow form as you move it over one of the vertical panel dividing lines. By

shifting the panel dividers, you can control how the overall window width is

partitioned between the three panels.


Using JKSimMet 175

5.3.13 The Sieve Series Window

The Sieve Series window displays a summary table of selected data for selected

streams in the flowsheet. The user can configure one or many tables for display

in this window.

The Sieve Series window can be opened by two methods:

1. Selecting Sieve Series from the Flowsheet menu.

2. Clicking on the Sieve Series button.

The Sieve Series feature can only be accessed when the flowsheet is locked.

The Sieve Series window provides a visual display of the different sieve series

available in the current flowsheet and the sieve series that each stream in the

flowsheet uses.

The Sieve Series window is discussed in more detail under the heading

5.3.14 The Survey Data Window

The Survey Data screen shows the survey size data for the sieve series in the

current flowsheet.



The Survey Data window can be opened by two methods:

1. Selecting Survey Data from the Flowsheet menu.

2. By clicking on the Survey Data button in the toolbar area.

The Survey Data window can only be accessed when the flowsheet is locked.

The Edit Sieve Series button is used to bring up the Sieve Series window.

The Transfer button is used to transfer the survey data into all of the streams,

replacing the experimental data. If the user has selected a sieve series that is not

the master series, the data will be transferred using the selected interpolation

method.

5.3.15 The System Properties Window

The global characteristics for the system property classes are defined in the

System Properties window.

The System Properties window can be opened by two methods:

1. Selecting System Properties from the Flowsheet menu.

2. Clicking on the System Properties button ( ) on the Flowsheet toolbar

The System Properties window can only be accessed when the flowsheet is

locked.

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Using JKSimMet 177

A drop-down list in the System Properties window shows the list of properties

that can be defined for use by JKSimMet. The System Properties function is

discussed in more detail within the chapter on Editing the Flowsheet Data.

5.4 Building and Manipulating a Flowsheet

In this section we will go through the process of building up a new flowsheet

from scratch and then examine how one can make modifications to an

existing flowsheet.

5.4.1 Loading an Existing Project

Loading an

Existing Project

In JKSimMet V6, each flowsheet is stored as a sub-unit of a project. Therefore,

to work with an existing flowsheet the user must first load the appropriate

project into the session window by clicking on Open Project in the File menu

or by clicking on the Open Project icon on the main toolbar (see topic File

Menu and Main Toolbar for more detail). This brings a standard Windows

Open dialog into view.

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Version 6.0.1 - March 2014Building and Manipulating a Flowsheet


Open Project Dialog

5.4.2 Creating a New Project

Creating a

New Project

To create a new project select New Project from the File menu or click on the New

Project icon on the main toolbar. A dialog box will request a name for the new

project. This name will be used as the file name and as the project name.

New Project Window

To change the name of an open project, use the Save Project As from the File menu

of the main JKSimMet menu. This will create an extra project with whatever new

Version 6.0.1 - March 2014 Building and Manipulating a Flowsheet

Using JKSimMet 179

name you give it. You can delete the original project if required - but remember that

you will need to delete both the .jksf6 file and the .jksysdb file. To clean up

completely, you will also have to delete the associated AutoSave files, which will

have been created while you have worked on this file under its original name.

There should be two of these; one for the .jksf6 file and one for the .jksysdb file.

When a new project is created, it will initially be blank and will be loaded with a

single blank flowsheet, which will be given the default name of FlowSheet1. More

flowsheets can be added to the project as required, see the Creating a New

Flowsheet section for further details.

Session Window Default Flowsheet

5.4.3 Loading an Existing Flowsheet

Loading an

Existing

Flowsheet

The list of existing flowsheets for the open project will be displayed in the left

hand section of the session window. Double click to open the desired flowsheet.

The flowsheet can also be opened by right clicking on the flowsheet name and

selecting Open. The name of the current flowsheet open in the project appears in

the title bar at the top of the JKSimMet session window, in the format ‘JKSimMet

– [Project Name – Flowsheet Name]’.

180



Session Window with Blank Default Flowsheet Loaded

5.4.4 Creating a New Flowsheet

Create a New

Flowsheet

To create a new flowsheet right click in the left hand section of the session

window and select Add New from the menu that appears. Any number of

flowsheets can be added in this manner. Double click on the name of a

flowsheet to make it the active flowsheet.

Creating a New Flowsheet

Add New creates a new flowsheet in the current project.

Open opens the selected flowsheet in the right hand side of the session window.

The flowsheet can also be opened by double-clicking on the flowsheet name (see

topic Loading an Existing Flowsheet ).

Clone a New

Flowsheet

Clone copies the flowsheet exactly. This option is particularly useful to run a

series of simulations while keeping the same flowsheet as a basis instead of re-

drawing and entering the data many times over. To clone a flowsheet, right-

click on the flowsheet and select "Clone" from the drop-down menu.

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Using JKSimMet 181

Deleting a

Flowsheet

If you need to delete a flowsheet that you have added by cloning or otherwise,

you can do this by once again right-clicking on this flowsheet in the left hand

panel listing and selecting "Delete" from the drop-down menu. Note that you

will not be able to delete the flowsheet if it is open in the right hand pane. If you

get a message that the flowsheet can't be deleted for this reason, just double-

click on another of your flowsheets before right-clicking again on the one you

are trying to remove. The delete function from the drop-down menu should now

work.

5.4.5 Defining the Flowsheet Name

As a project can contain more than one flowsheet it is advisable to give each

flowsheet a unique name. The list of flowsheets for a project appears in the left

hand side of the session window. New flowsheets created in JKSimMet are

given default names – FlowSheet1 for the first and then FlowSheet2,

FlowSheet3 etc. To edit the flowsheet name, right click on the flowsheet name

and select Properties from the menu to open the Flowsheet Properties

window.

To change the name of the flowsheet the user must highlight the text in the

Flowsheet Name box, type in the new name (maximum 50 characters) and

press OK to register the name. The new flowsheet name will appear in the left

hand side of the session window.

The user can also edit the Comments text for the flowsheet, however note that

there is a 50 character limit for this text.

5.4.6 Deleting a Flowsheet

Right clicking on the flowsheet name in the left hand side of the session

window opens a pop-up menu.



The Pop-Up Menu

Delete deletes the flowsheet. An open flowsheet cannot be deleted. A flowsheet

can be closed by clicking on the Close icon in the top right hand corner of the

flowsheet window (not the Close icon in the top right hand corner of the session

window), or by opening another flowsheet. The closed flowsheet can then be

deleted.

5.4.7 Building the Flowsheet - Equipment

When ‘FlowSheet1’ has been loaded, the user is presented with a blank

flowsheet. The first step in entering the data for the project is to build the

flowsheet.

JKSimMet uses an equipment unit to represent each process on a flowsheet.

The list of equipment that is available in JKSimMet is shown below in the

same form as it appears in the Session window.


Using JKSimMet 183

The default equipment has typical values for the equipment dimensions,

model parameters etc. as its default data. The user can edit these data at any

time.

Circuit Feed JKSimMet uses the Feed equipment unit to introduce the feed flow to the

circuit. This means that the parameters of the feed stream are actually defined

in the Feed equipment rather than in a ‘Feed stream’. A flowsheet therefore

must contain at least one Feed equipment unit.

Adding

Equipment to the

Flowsheet

To place the appropriate equipment icons on the flowsheet:

1. Unlock the flowsheet by clicking on the Lock/Unlock icon, by

selecting Lock from the Flowsheet menu or by selecting Lock/Unlock

from the right click menu on the session window.

2. Click on the icon of the desired equipment.

3. Move the cursor to where the unit is to be drawn on the flowsheet and

click to place the unit. To place multiple units of the same equipment

type, hold down the control key while selecting the equipment type

from the equipment list, then repeatedly click in the flowsheet to place



as many units as required.

Alternatively, additional units may be placed by placing a first unit in the

usual way, pressing the Copy button and then using the Paste function to

place as many units as are required.

Editing

Equipment on

the Flowsheet

To edit equipment once it has been placed on the flowsheet, double click on

the item of equipment in the flowsheet. The flowsheet must remain in

unlocked mode to access the editing features. The equipment can then be

moved and have its name and orientation changed, as described below.

Moving

Equipment

To move equipment to a different position on the flowsheet place the cursor

over the equipment and hold the left mouse button down while dragging the

equipment to its new position. When the equipment is in the required position

release the mouse button to place the equipment. Any streams that are

attached to the equipment will remain attached after movement of the unit.

Naming

Equipment

The equipment is given a default name when it is initially added to the

flowsheet. To change the name of the equipment double-click on the

equipment and type in the new name next to the Name in the Component

Properties window and click OK.

Displaying

Equipment

Name

The Equipment Auto Labels icon can be used to display the equipment name

on the flowsheet. When the Equipment Auto Labels icon is selected an

equipment label will automatically appear when equipment is added to the

flowsheet. The equipment label takes the Equipment Name from the

Component Properties window, as described above. The Equipment Auto

Labels function is discussed in more detail in the chapter on Annotating the

Flowsheet .

Orientation The orientation of the equipment can be changed so that the feed end of the

equipment changes from left to right or vice-versa. The default orientation is

the feed on the left and the products on the right. Select one of the ‘Flip’ or

‘Rotate’ buttons on the toolbar to change the equipment orientation.

Deleting

Equipment

To delete equipment ensure the flowsheet is unlocked and click on the

equipment to be deleted. Once selected press the ‘Delete’ key or select ‘Delete’

from the ‘Edit’ pull-down menu.

5.4.8 Building the Flowsheet - Streams

JKSimMet uses streams to represent the flow of material (solids and water)

between the equipment on the flowsheet. Material enters equipment through

its feed inlet and leaves equipment through its product outlet(s). The flow of

material between the equipment is created on the flowsheet by connecting the

feed and product outlets of the appropriate equipment items.

Although the drawing engine does not impose a limit on the number of feed

streams that can be connected to an individual equipment unit, the simulation

engine does only recognise the first 50 feed streams per equipment item. Note

that there is also a limit on the total number of streams per flowsheet and this

limit has been set at 999.

The number of product outlets from an equipment item depends on the type of

equipment; for example a flotation cell has two product outlets, a pump sump

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Using JKSimMet 185

has one product outlet.

Note that there are two specialised equipment items that do not have a feed

inlet. These are the Feed equipment item, which is the source of new feed to a

circuit, and the Water Feeder, which is the source of water addition to a

circuit.

Adding a Stream

to the Flowsheet

Streams can be added to the flowsheet in a similar manner to equipment. Once

tee equipment has all been added to your flowsheet, it is simply a matter of

using your mouse to join the appropriate output and input ports of the

various equipment items.

1. Unlock the flowsheet by clicking on the Lock/Unlock icon or by

selecting Lock from the Flowsheet menu. In unlock mode the

flowsheet may be altered.

2. To connect a product outlet to a feed inlet, place the cursor over the

product outlet or feed inlet of an equipment item. When the cursor

changes to a circle containing a cross, left click to start the connection

process. The cursor will then change to a cross and when you now

move the mouse, it will drag a line representing the stream to

wherever you select as the destination.

3. When you have positioned the cursor over the inlet or outlet (as

appropriate) of the destination equipment item, the cursor will again

turn into a circle containing a cross. Note that this will only happen

where a connection is possible. If you have started at an inlet port and

you move to another inlet port, the cursor will not change because in

this case the connection is not possible. When the cursor has changed

to indicate the potential for connection, left-clicking again will

complete the stream.

Streams can be connected in straight lines in this manner, or they can be made

to follow more complex paths. The above procedure will produce a connection

that is just a straight line stream from one item of equipment to another. While

a straight line stream may be acceptable in a very simple circuit, more often

than not you will require points of inflexion so that your streams take a less

direct route to their destination. You can achieve this during the connection

process if you left click at the various intermediate points where you require

the stream to change direction. Again, you just terminate the stream when the

cursor turns to a cross within a circle over the destination port.

To produce the stream connection below for instance, left-click over the outlet

from the feeder, move the cursor downwards to the desired position for the

right angled bend and click again. Finally, move the cursor to the right and

click on the flotation cell inlet to complete the stream.



Flowsheet with a Single Stream Connection

Note that if you wish to abort the drawing of a stream at any point during the

process, all you have to do is right click and the entire stream you have

entered to that point will disappear.

Editing a Stream

on the Flowsheet

To edit the formatting of a stream once it has been placed on the flowsheet

double click on the stream. The flowsheet must be in unlocked mode to access

the editing features. This will open the Common Properties window for the

chosen stream.

Naming Streams The streams are given default names when they are initially added to the

flowsheet. To change the name, open the Component Properties window by

double-clicking on a stream. Type in the new name into the Name text box and

click OK. It is recommended that the streams be given meaningful names such

as ‘Cyclone O/F’, ‘Ball Mill Feed’ etc, so that they can be easily identified.

Displaying

Stream Name

Labels can be added to the flowsheet to display the stream names using the

Stream Auto Labels icon. Labels are discussed in more detail under the

heading Annotating the Flowsheet .

Manually Re-

route Streams

JKSimMet provides a mechanism for re-routing existing streams in the event

that you are not satisfied with your initial placement. First ensure the

flowsheet is unlocked and then right-click on the stream you wish to re-route,

at the point where you require the point of inflexion (or stream node). The

right-click menu will look similar to the image below.

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Using JKSimMet 187

Click on the Add/Remove Stream Node menu item. This will insert a new

stream node at the cursor location. You can then move the cursor over this

new node, then left-click and drag it to the location required for re-routing this

stream.

You can remove a stream node in a similar manner. For this you need to bring

up the right-click menu while the mouse is hovering over the stream node in

question. Selecting the same menu item will in this case delete the stream

node.

Deleting a

Stream

Whole streams can be deleted in the same manner as equipment items. Ensure

the flowsheet is unlocked, then click on the stream to be deleted. Then you can

either press the Delete key or select Delete from the Edit pull-down menu.

Before the stream is actually deleted you will get a warning and an

opportunity to cancel, so as to guard against accidental deletion.

Once all of the equipment and streams have been added to the flowsheet and

the editing of names is complete, lock the flowsheet by clicking on the blue

Lock icon, by selecting Lock from the Flowsheet menu or by selecting Lock

from the right click menu in the session window.

5.4.9 Annotating the Flowsheet

JKSimMet allows the user to annotate the flowsheet by adding general labels

to the flowsheet or by adding equipment or stream specific labels, as well as

information blocks.

There are three ways in which labels can be added to the flowsheet:

1. General Text Labels – used to add general text (e.g. circuit name) to

the flowsheet; the labels can be moved independently around the

flowsheet.

2. Equipment Labels – used to automatically add the equipment name

as a label near the equipment on the flowsheet; the label becomes part

of the equipment and moves when the equipment is moved.

3. Stream Labels – used to add labels of the existing stream names to the

flowsheet; the labels are of the same form as the Equipment Labels.

Adding General

Text Labels to

the Flowsheet

To add General Text Labels to the flowsheet:

1. Unlock the flowsheet by clicking on the Lock/unlock button or by

selecting Lock from the Flowsheet submenu.

2. Select the ‘Text’ icon from the toolbar. A text icon now appears next to

the cursor when it is placed over the flowsheet.



3. Move the cursor to the desired location and click to place the label.

4. Double click the label and type in the desired text. Press ‘Enter’ when

finished.

Editing Labels on

the Flowsheet

To edit a label once it has been placed on the flowsheet click on the label. The

flowsheet must remain in unlocked mode to access the editing features. A

label can then be moved and be edited, as described below.

Moving Labels Text labels can be moved in the same manner as equipment. Simply place the

cursor over the label and hold the left mouse button down while dragging the

label to its new position. When the label is in the required position release the

mouse button to place the label.

Changing the

Text of a Label

To change the text of the label, double-click on the label and type in the new

text. Press ‘Enter’ to complete.

Deleting Labels Labels can be deleted in the same manner as equipment and streams. Ensure

the flowsheet is unlocked then click on the label to be deleted. Either press the

‘Delete’ key or select ‘Delete’ from the ‘Edit’ pull-down menu.

Adding

Equipment

Labels to the

Flowsheet

To automatically add the equipment name as a label above the equipment on

the flowsheet click on the Equipment Auto Labels button. To remove the

equipment name labels click on the Equipment Auto Labels button again. The

Equipment Auto Labels function is available whether the flowsheet is locked

or unlocked.

Editing

Equipment

Labels

Unlike the general labels, the labels added to equipment on the flowsheet

using the Equipment Auto Labels function cannot be independently renamed.

These equipment labels become a part of the equipment; they move when the

equipment is moved, are renamed when the equipment name is changed

(using Equipment Properties, see topic Property Windows ) and are deleted

when the equipment is deleted. The position of the label in relation to the

equipment can be changed, however. To do this, double click on the label or

the equipment to bring up the Component Properties window. Select the ‘Auto

Label’ tab and select an option for the positioning of the label relative to the

equipment. Note that clicking the ‘On/Off’ option in this tab will mean that

the label for this particular item of equipment will not be displayed on the

flowsheet.

Stream Labels may also be edited using the same procedure as Equipment

Labels.

Adding Stream

Labels to the

Flowsheet

To automatically add labels of the existing stream names to the flowsheet:

1. Unlock the flowsheet by clicking on the Lock/unlock button, by

selecting Lock from the Flowsheet submenu or by selecting Lock from

the right click context menu in the session window.

2. Click on the Stream Auto Labels button.

IMPORTANT

NOTE

Note that if the stream names are changed subsequent to adding stream labels

to the flowsheet, the stream label text automatically changes, however the

stream label box does not automatically resize to match the size of the new

stream name. To fix this, click the Stream Auto Labels button to remove the

labels, then click on the Stream Auto Labels again to add the labels again.

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Using JKSimMet 189

5.4.10 Information Blocks

On opening the Information Blocks window (via the toolbar button or the

Flowsheet menu) the user will be presented with a tabbed display, with one tab

for setting up Stream Information Blocks and one for Equipment Information

Blocks.

Stream

Information

Blocks

The same data is displayed for all active Stream Information Blocks. You cannot

tailor the blocks for individual streams so that they are different from those of

other streams.

The procedure for adding Stream Information Blocks is as follows:

1. First ensure that the Stream tab is active.

2. From the first drop-down box, select the number of parameters to be

displayed in the Information Block.

3. Select the basis stream for recovery calculations. Note that his selection

is only needed if a recovery value is to be one of the display fields and

this will only be a possibility in cases where mass balancing is being

performed.

4. Next left click on each parameter cell in turn to select the data that you

wish to have displayed in that cell. Each time you do this, another

window labelled Selection Options will open. Here you specify the type

of data to be displayed in more detail. A screen grab of this window is

shown below.

5. In this window you work your way down (starting with the drop-down

at top left in Selection Options), to make a full specification of the data

type that is to be displayed in the selected cell. Note that lower drop-

downs will become available when needed, depending on your

selections in the drop-downs above. The name that will appear in the

stream information block key for this data cell is auto generated by

default. You will notice that there is a tick in the Auto Generate Name



box when the window opens. If the system generated name is too long

however, you can manually enter an abbreviated form, after clicking to

remove the tick from this check-box.

6. Select the stream or streams for the info block – multiple selection can be

achieved using the ‘Ctrl’ and ‘Shift’ keys.

7. Click ‘Add Info Block’ to add the blocks to the flowsheet.

The Info Blocks will be added to the flowsheet, roughly centred on each stream.

In addition there will be a key displayed at the top left of the flowsheet that will

show which parameters are displayed in which cells of the Info Block.

To modify the information displayed in the Stream Information Blocks, make the

changes required and click ‘Update Selected Info Blocks’.

Remember that the same data is displayed for all streams, so clicking ‘Add Info

Block’ after changes have been made in the Stream Info box tab will result in all

of the Stream Info Boxes updating.

Equipment

Information

Blocks

Equipment blocks are conceptually different to Stream blocks, but operate in a

similar way. As each Equipment unit may use a different model and therefore

different data, the information blocks are set up on a per unit basis.

The procedure to add an Equipment Information Block is:

1. Select the equipment unit or units for the info block – multiple selection

is achieved with the ‘Ctrl’ and ‘Shift’ keys.

2. Select the number of parameters to be displayed.

3. Left click on each parameter cell to select which data is to be displayed

in that cell. The selection method is the same as the Configurable

Equipment Manager, except that the parameter name is also defined.

Click ‘Close’ when finished.

4. Click ‘Add Info Block’ to add the blocks to the flowsheet.

The info blocks will be added to the flowsheet, adjacent to each unit. The

parameter names will be displayed in the cell next to the values.


Using JKSimMet 191

To modify the information shown in one or more Equipment Information Blocks,

make the changes required in the Equipment Info box tab, select the Equipment

unit or units to modify and click ‘Update Selected Info Blocks’.

General

Information

When the flowsheet is unlocked, the Info Blocks may be moved, resized and

deleted using the ‘Delete’ key.

The data that is not able to be edited will be greyed out. Other values can be

edited, and will update throughout the system.

5.5 Editing the Flowsheet Data

Overview Once the flowsheet has been built complete with equipment and connected by

streams to form a circuit, the next step is to input the data itself. The flowsheet

must first be locked by clicking on the Lock button, by selecting Lock from the

Flowsheet menu or by selecting lock from the right click menu in the session

window. Once locked the System Properties, Sieve Series, Survey Data,

Configurable Equipment Manager, Run Simulation, Configurable Stream

Overview, Simulation Manager, Run Balance, Equipment, Stream, Reporting,

Config Graph and Setup Info Blocks icons are all accessible. These tools will

be described in subsequent sections.

Data Entry

Conventions

There are three different background colours used to represent the different

types of data in the JKSimMet windows:

1. White – the user is required/permitted to enter data (e.g. feed

tonnage).

2. Light grey – this data does not change (e.g. some labels).

3. Medium grey – user entry is not required but the data will change

depending on a user selection or calculation during simulation (eg a

calculated value such as pulp volume of each cell).

These conventions apply to all of the data windows.

Note that the exact appearance and colours of each window will also depend

on the setup of the MS Windows desktop.

5.5.1 Stream Structure

After input of the feed stream data and equipment and model data, JKSimMet

predicts the sizing and mass flow data in the streams throughout the circuit

using an iterative technique.

Comminution models are used within each of the specified comminution

equipment units to determine the resulting size data for the relevant output

streams. A detailed explanation of the terms used to define the stream

structure has been provided under the heading Definition of Terms Used in

JKSimMet .

Remember that the feed stream data are defined in the ‘Feed’ equipment item

rather than in the stream from this unit.

135

Version 6.0.1 - March 2014Editing the Flowsheet Data


5.5.2 System Properties

System

Properties

Click on the System Properties icon or select System Properties from the

Flowsheet sub menu to open the System Properties window.

There are two system property classes available to the user; Elements and

Miscellaneous items. The user has the option of defining as many or as few

elements as required, but cannot define additional miscellaneous items.

The two classes of system properties are accessed via a drop-down list at the

top of the System Properties window, under the heading Select property.

System properties must be defined for each flowsheet; they cannot be copied

between flowsheets or between projects.

Miscellaneous The first item on the drop down list is Miscellaneous and this will be chosen

initially by default. There are just two miscellaneous items in the system for

which you need to set values; Solids SG and Liquid SG. The default values are

2.7 and 1.0 (t/m3) respectively. You can simply edit these values in the white

cells to adjust them if required.

Elements The other item on the Select property drop down is Elements. In JKSimMet

elements are only needed for the mass balancing function of the program. If

you are not going to be doing any mass balancing, then it is not necessary to

enter any elements into the system for the flowsheet in question.

If you do need to specify elements, firstly select Elements from the drop-down.

Once you do this you will see the appearance of the window change to

resemble the screen capture below, which in this case also shows the

expanded drop-down.

Adding Elements The main difference you will notice after Elements has been selected, is that a

Delete selected row(s) button will be present at bottom left. This is to provide

the option of removing elements already in your list if you have changed your

mind or made an error.

The table is configured such that it will always contain a blank row at the

bottom where you can add further elements. When you enter an element you

can either leave the units in the adjacent Units cell with the default setting of

"%" or else select "g/t" (if appropriate) from the drop-down in this cell. To

remove an element that is not required, click anywhere in the row you wish to

remove and use the Delete selected row(s) button.

There is no limit to the number of elements that can be added.

Version 6.0.1 - March 2014 Editing the Flowsheet Data

Using JKSimMet 193

The width of the columns can be changed by placing the cursor on the right

border of the column in the heading row, then holding down the left mouse

button and dragging the cursor.

IMPORTANT

NOTE

Note that there is no internal check of consistency of these data in JKSimMet. It

is up to the user to ensure that the SG values are correctly defined.

When all changes to the System Properties window have been made, click on

the Close button to close the window.

5.5.3 Accessing the Equipment and Model Data

The Equipment and Model windows contain all of the information about the

equipment that JKSimMet requires to perform simulation tasks.

Accessing the

Equipment Data

The data for the equipment can be viewed in the Equipment window. The

Equipment window can be opened by:

1. Double-clicking on the equipment in the flowsheet.

2. Selecting Equipment on the Flowsheet menu or clicking on the

Equipment icon.

Equipment

Window Layout

There is one Equipment window in JKSimMet; all of the equipment can be

accessed via the Equipment Name drop-down list in the Equipment window.

The Equipment window can only be accessed when the flowsheet is locked. A

typical Equipment window is shown below.

A Typical Equipment Window

The Equipment window also shows the feed and product streams from the

selected equipment. Clicking on the double arrow buttons next to the streams

that are feeds or products from the selected equipment; opens the Streams

window, which enables display of stream data.



5.5.4 Editing the Model Data

The Model window collects the data required for the selected model

calculation and displays the equipment parameters calculated during

simulation.

Selecting a

Model

The Equipment Model drop-down list in the Equipment window shows the

models available for the selected equipment. All models for a particular type

of equipment are available for selection.

Accessing the

Model Window

Select a model and click on the double arrow button next to the selected

equipment model to open the Model window.

Model Window

Layout

The Model window for all the models has the same general layout, see below.

Click on the tabs at the top of the Model window to input and view the model

data. The data layouts for all of the model types are detailed in the Model

Descriptions section. Note that some of the calculated model data will

update on input and some will update only after simulation.

Copy Grid The Copy Grid button allows the user to copy the currently displayed grid to

the clipboard, from where it can be pasted into other applications.

Units in Parallel The units in parallel text box is used to show how many of the selected unit in

question exist at this location in the circuit.

A Typical Model Window

Parameter

Values

If a value is entered for a parameter that is outside the normal range for the

parameter, JKSimMet will display a warning message. Users are given the

choice of either having the value entered clipped to the nearest edge of the

normal parameter range (eg, for a range of 1 to 15, an entered value of 20

would be clipped to 15) or continuing with the entered value.

294


Using JKSimMet 195

If the user needs to know the maximum and minimum values for a parameter

value, double clicking on the cell for that item will launch the Parameter

Detail window. This displays the minimum and maximum values, as well as

the default value and other available information about the selected

parameter.

5.5.5 Editing Equipment Data

There are two options for viewing and editing the equipment and model data.

The first option is to access the Equipment and Model windows for the

individual equipment units as previously described . The alternative is to

use the Configurable Equipment Manager, which allows the user to view and

edit data for all units of the same type in a summary table format. This can be a

more efficient means of accessing equipment data during simulation work. As

its name implies, the Configurable Equipment Manager can be configured as

required by the user.

The Configurable Equipment Manager window displays a summary of selected

equipment unit parameters. The user can configure multiple summary tables

for display and can edit the values displayed in these tables. This window

provides a simpler and more efficient means of reviewing and adjusting

equipment information than using the individual equipment data screens.

The Configurable Equipment Manager window can be opened by two methods:

1. Selecting Configurable Equipment Manager from the Flowsheet menu.

193



2. Clicking on the Configurable Equipment Manager button.

The Configurable Equipment Manager can only be accessed when the flowsheet

is locked.

Configurable Equipment Manager provides a summary of the equipment unit

data for selected units in the flowsheet. The information displayed in the

Equipment Overview screens is exactly the same as the information displayed

in the model screens for the individual equipment units.

The summary table can be printed directly from the dialog, copied to the

clipboard for pasting into other programs such as Word or exported to Excel

for further analysis.

A Typical Configurable Equipment Manager Window

Configurable

Equipment

Manager

Window

The Configurable Equipment Manager window has four main components:

1. Current Overview drop-down list

2. Configurable Equipment Manager toolbar

3. Model drop-down list

4. Data table

Current

Overview List

The user can create one or more Configurable Equipment Manager tables. Each

table created is listed by name in the Current Overview List drop-down,

allowing the user to change from one table to another by selecting the required

configuration from the list.

Configurable

Equipment

Manager

Toolbar

The toolbar allows the user to create new configurations, delete unwanted

configurations, add or delete data columns, print, copy or export the data to

Excel.

New Unit

Overview

To create a new configuration the user clicks on the New Unit Overview

button. This opens the Add Unit Overview dialog which prompts the user to

enter a name for the new overview and to select from the Select Model drop-


Using JKSimMet 197

down list, a model that is to be associated with this newly configured

overview.

Delete

Overview

Clicking on the Delete Overview button deletes the current overview. A

warning dialog asks the user to confirm that the current configuration is to be

deleted as this operation cannot be undone.

Rename

Overview

The Rename Overview button allows the user to rename the selected overview.

Insert Column Inserts a blank data column to the right of the column where the cursor is

currently located.

Delete columns Deletes the column where the cursor is currently located. Note that the column

is deleted immediately without the user being asked to confirm their action.

Print Overview Prints the current overview table.

Copy Grid Copies the entire data grid for the current overview to the clipboard, allowing

the data to be pasted into other programs such as Word.

Lock Cols When this button is unlocked (appearing as shown in image at left) the user is

able to change the position of the columns of data.

Export

Overview

Exports the data for the current Equipment Manager overview to Excel.

Clicking on the Export Overview button opens the Export Report to Excel

dialog where the user can enter a name for the Excel file and choose where to

save the file. Note that if the file name chosen is the same as an existing Excel

workbook, the user is prompted to choose whether to overwrite the existing

workbook or to append the current data as a new worksheet in the existing

workbook. The name of the Overview which has been exported is shown in the

tab of the Excel worksheet.

Export All As for Export Overview, except that in this case all of the overviews listed in

the Current Overview drop-down list are exported to Excel, each on a separate,

named worksheet in the workbook.

Below is an example of a new overview that has been created for cyclones in a

flowsheet that are using the Asomah Advance Inclined Cyclone model. In this

case there is only the one cyclone using this model. The overview has been

configured to show the cyclone diameter (Dc) under the Operating Conditions

category of parameters and also the various data types associated with the

Water Split to Overflow parameter under the Performance Data category of



parameters.

An Example of the Default Configurable Equipment Manager Layout

Configuring a

New Data

Column in the

Overview

When a new column is added to the Overview table by clicking on the Insert

Column button, the added column is headed No Selection and contains no

data. The user must select the data to be displayed in the column by first

ensuring that the Lock Cols button is locked and then clicking on the header

cell for the column. This opens the Tab/Options/Parameter dialog.

The user can select the required options from the drop-down lists in the dialog.


Using JKSimMet 199

The selected parameters are then displayed in the overview table.

Adding or

Deleting

Equipment

Units

The user is able to add or remove equipment units from a configuration. Data

for other unit types or similar unit types that are using a different model, must

be viewed and edited by setting up another configuration for that model type.

Changing the

Data Column

Order

To change the order in which the data columns are displayed the user must

unlock the Lock Cols button, select the column in the data table by clicking in

the header cell and then drag the column to its new location on the table as

indicated by a red line. Two or more adjacent columns can also be moved by

selecting all of the columns together (click and drag or Shift-click) and

dragging the group to their new location in the table.

5.6 Using Simulation

During simulation JKSimMet calculates the mass flow of the particle classes

in each stream of the flowsheet. The mass in each particle class in the product

streams of each equipment unit is calculated using the mass in each particle

class in the feed stream(s) to the equipment and the model algorithm for the

equipment. These calculations are performed iteratively until the difference in

the stream flows from two consecutive iterations are below a specified

convergence limit. The particle class information is then combined to enable

calculation of the data displayed in the Stream data and Stream Overview

windows. Various unit parameters are also calculated during simulation and

can be viewed in their associated equipment data windows.

What Simulation

Requires

Prior to simulation, the user must:

1. Create the flowsheet (see Section 4.5). Note that each feed stream to a

comminution circuit (unless it consists entirely of water; see Water

Feeder models in Appendix B3) must be preceded by a Feed

equipment unit before it can be simulated. In addition, all equipment

units must have feed streams for the flowsheet to be valid.

2. Define the characteristics of the property classes in System Properties

(see Section 4.6.2).

3. Input the feed stream data in the Feed equipment unit (see Appendix

B2).

4. Select the models for each equipment and input the required model

data (see Sections 4.6.4 to 4.6.6).

Version 6.0.1 - March 2014Using Simulation


Performing

Simulations

Simulation within JKSimMet can be performed in two ways. If the user simply

wants to simulate the circuit with the current equipment and feed stream data

values only, the Simulation window is used. Alternatively, the Simulation

Manager allows one or more simulations to be performed on the flowsheet

with the user being able to set selected data values (e.g. solids flow rate, %

solids) for each simulation in the batch. The use of each simulation control is

described below.

5.6.1 Simulating Using the Simulation Window

Accessing the

Simulation

Window

To perform a simulation with the current data in the flowsheet the Simulation

window is used. The Simulation window can be opened by two methods:

Selecting Run Simulation from the Flowsheet menu, or

Clicking on the Run Simulation icon.

Simulation

Select

The system provides a default simulation for the whole circuit; the user is then

free to create new simulations and delete or rename the simulations that they

add. The whole circuit simulation cannot be renamed or deleted.

Add a new

circuit

Choosing to add a new circuit brings up this dialog, where the user can choose

to accept the default name or enter a name of their choice.

On returning to the main simulation dialog, the user can then choose which

equipment and streams they require for the new simulation

Equipment /

Streams

In all simulations except the default whole circuit simulation, the user can

choose which equipment items and streams are to be used by the simulation.

Version 6.0.1 - March 2014 Using Simulation

Using JKSimMet 201

Settings The options in the settings area allow the user to set the convergence limit, set

the iteration count, choose the interpolation method and set the starting

condition for the simulation.

Interpolation options

Starting Conditions

Run

Simulation

When the user has selected the simulation that they wish to run, checked the

choice of the selected equipment and streams and reviewed the settings for the

simulation, they click the start button to run the simulation. The simulation will

run until either the specified iteration count is reached or the fitted convergence

value reaches accuracy level specified in the settings. As the simulation runs it

provide the user with feedback by updating the Convergence and Iteration

count text boxes.

5.6.2 Simulating Using the Simulation Manager

The Simulation Manager is a powerful feature that allows multiple

simulations to be performed in a batch operation. The user can set a range of

key operating parameters in the simulations and record the key performance

indicators for each simulation performed. The results of all of the simulations

within a scenario can then be viewed on the same screen, allowing direct

comparison of simulated flowsheet data under different operating conditions.

The user is able to view any parameter relating to stream or equipment unit

data. The equipment viewing platform is similar to the Configurable

Equipment Manager viewing platform

Accessing the

Simulation

Manager

Click on the Simulation Manager icon or select Simulation Manager from the

Flowsheet menu to open the Simulation Manager window. The Simulation

Manager window consists of the Simulation Manager toolbar and three data

tabs, one for setting the simulation conditions (Simulation Scenario) and two

for viewing the simulation results (Results - Streams and Results - Equip).

When the Simulation Manager window is opened, the Simulation Scenario tab

is active.



Simulation

Scenarios

The Simulation Manager allows the user to perform multiple flowsheet

simulations varying key operating parameters in a batch operation called a

Simulation Scenario. Any number of Simulation Scenarios may be created,

however only one Simulation Scenario may be active at any one time. The

active Simulation Scenario can be changed to another previously created

scenario by selecting the required item from the Scenario Name drop-down

list.

Within each Simulation Scenario, the user can create a large number of

simulations to investigate the effects on the circuit performance of a single

parameter, or the effects of different values of a multiple of equipment

parameters. The results of these simulations can then be viewed in the

different results tabs of the Simulation Manager.

The different areas of the Simulation Manager window are as follows:

1. Toolbar – contains the functions to configure and use the Simulation

Manager. The toolbar is always visible at the top of the window.

2. Tabbed data viewing region – each tab contains a data display header

and a data display area, and only one tab can be viewed at any one

time. The three tabs display the simulation conditions and simulation

results:

a) Simulation Scenario – used to define the equipment parameters

which are to be varied in the simulations and to set the value of

each parameter for each simulation;

b) Results - Streams – for viewing results associated with streams on

the simulated flowsheet;

c) Results - Equip – for viewing results associated with equipment

units on the simulated flowsheet.

Data Display

Header

The parameter description is displayed in the data display header in each of

the tabs. See further down in this topic under the heading Selecting the


Using JKSimMet 203

Parameters for the method used to select the parameters.

Note that all of the drop-down lists in the data display header list items in

alphabetical order.

Data Display

Header:

Simulation

Scenario Tab

The data display header for the Simulation Scenario tab is similar to the data

display header in the Configurable Equipment Manager, containing data

headers to describe the selected parameter. These data headers are:

Row 1 – Equipment name

Row 2 – Model Tab

Row 3 – Model Tab Option

Row 4 – Parameter name

Rows 5 to 7 – Description of property specific parameters

Row 8 – Type of Change: choose either replacing the value of the

parameter with a user defined value (select Value), or increasing or

decreasing the value of the parameter by a defined percentage (select

% Change).

Row 9 – Original Data: the ‘base case’ value of the parameter is

automatically displayed when the parameter is added. This provides

a reference point for comparison with the other simulations results.

Data Display

Header: Results-

Streams Tab

The data display header for the Results - Streams tab is similar to the data

display header in the Configurable Stream Overview, containing five data

headers to describe the selected stream data.

Row 1 – Stream name

Row 2 – Property

Row 3 – Calculation Type: select

Row 4 – Assay Basis



a reference comparison point for the other simulations.

Data Display

Header: Results-

Equip Tab

The data display header for the Results - Equip tab is similar to the data

display header in the Configurable Equipment Overview, containing several

data headers to describe the selected parameter. These are:

Row 1 – Equipment name

Row 2 – Model Tab

Row 3 – Model Tab Option

Row 4 – Parameter name

Rows 5 to 7 – Description of property specific parameters



a reference comparison point for the other simulations.

Using the

Simulation

Manager

Using the Simulation Manager requires the user to:

1. Create a Scenario in the Simulation Scenario tab.

204



2. Select the parameters to be varied for the simulations.

3. Define different simulation conditions.

4. Select the parameters to be displayed in the Results - Streams tab and

the Results-Equip tab.

5. Perform the batch simulation.

Delete Scenario The current Scenario can be deleted by clicking on the Delete Scenario button

from the toolbar at the top of the Simulation Manager window. Click Yes to the

prompt to delete the current scenario.

Rename

Scenario

The current scenario can be renamed by highlighting the existing name in the

Scenario Name box and typing the new name to replace the old one.

Create a Scenario Click on the Simulation Scenario tab, then click on the New Sim Scenario

button on the toolbar at the top of the window, type in the name for the new

scenario and click OK.

The Simulation Scenario tab then displays one column in the data display

area with ‘No Selection’ in the top row of this column.

Note that when selected subsequently, a particular Simulation Scenario

window appears as it was last left by the user.

Selecting the

Parameters

The Simulation Scenario windows can be configured by the user to allow

many parameters to be varied in the simulation. The parameter displayed in a

column can be changed by editing at any time. New columns can be added,

and existing columns deleted as required using the Insert Column and Delete

Column buttons on the toolbar.

Adding a New

Parameter

To add a new parameter to the Simulation Scenario tab display, first click in

the data display area of the window then click on the Insert Column button on

the toolbar. A new column will be added to the right of the cursor position.

When a new column is added to the scenario, the words ‘No selection’ are

displayed in the top row of the column. This parameter description can be

changed as outlined below.

Changing

Existing

Parameters

To display a different parameter (or to select a parameter for the first time),

lock the columns, then click in the top row in the data display header of that

column (initially this row will display ‘No selection’). A new window

appears to select the parameter.

In this window the user selects the required parameter from the drop-down


Using JKSimMet 205

lists by selecting first the Equipment unit for the parameter, and then the Tab,

Option and finally the Parameter to be displayed. Note that the Equipment/

Group drop-down list contains all of the equipment units in that flowsheet, in

alphabetical order. The Tab, Option and Parameter are selected in an identical

manner to the Configurable Equipment Overview.

When parameter selection is complete click on the Close button. The

parameter description will then be displayed in the data display header of

the Simulation Scenario tab. The Type of Change and Original Data are also

displayed at the bottom of the data display header.

If a parameter is selected that requires further property-specific parameter

selection, then a Select Properties window opens on top of the Simulation

Manager window, as is the case in the Configurable Equipment Manager. This

window opens after the user has made the Tab, Option and Parameter

selections and then clicked on Close in the Equipment/Tab/Option/Parameter

window.

An Example of a Select Properties Dialog

The Select All and Deselect All buttons can assist in the selection of the

specific properties. When this window is closed by clicking on the Close

button, the property combinations that were checked are then displayed as

one parameter per column under the overall parameter label in the Simulation

Scenario tab, as shown below.



An Example of the Simulation Scenario Tab After Parameter

Selection

Delete a

Parameter

To completely delete a parameter from a tab in the Simulation Manager, place

the cursor on the column/s to be deleted then click on the Delete Columns

button from the toolbar. The whole column will then be deleted from the

window. Note that the deletion occurs immediately.

Setting Up

Simulations

The Simulation Scenario tab is used to define the conditions for the different

simulations that are to be performed in the current scenario. Place the cursor

in the data display area and click on the Insert Simulation button on the

toolbar. A new row for a new simulation will be inserted in the row below

where the cursor was placed. Each simulation is automatically given a name,

Simulation 1, Simulation 2, etc. It is also possible for users to change the

names of the simulations. When a simulation has been inserted, ensure that

the ‘Lock Cols’ button is pressed and then double click in the cell which reads

‘Simulation 1’ (or ‘Simulation 2’ etc depending on the number of simulations

inserted). Type in the new name for the simulation and press ‘Enter’ when

complete.

A simulation can be deleted from the Simulation Scenario tab by selecting the

row to be removed and then clicking on the Delete Simulations button on the

toolbar.

Entering Data Once a simulation has been created as a row in the Simulation Scenario tab,

new parameter values for that simulation can be entered into the appropriate

columns. To do this, click on the parameter cells for a given simulation and

type in the Value or % Change value to be used for each parameter in the

simulation. The Original Data value for each parameter can be seen in the

bottom row of the data display header for comparison purposes.

Note that other than the parameters selected for display in the Simulation

Scenario tab, all other data used in the simulation calculations are the current

data for the flowsheet. In other words, only the parameter values displayed in

the Simulation Scenario tab can be varied in the simulations – all other


Using JKSimMet 207

parameters remain fixed at the values that have previously been entered for

each equipment unit, and the feed stream, in the respective Equipment and

Stream windows.

If there are no data entered on the Simulation Scenario tab for a parameter for a

particular simulation (i.e. the cell is left blank), the Original Data value for

that parameter will be used for simulation calculations. Note that the range

limits for parameters are applied when the simulation is run.

Different Simulation Scenarios as well as different simulations within a

scenario may be used to determine the effects of changing parameters on the

circuit performance. For example, it may be useful to determine the effect on

circuit performance of only one parameter at a time, in which case the

Simulation Scenario would only have one parameter selected. A new

Simulation Scenario would then be created to determine the effect on circuit

performance of a different parameter.

The Simulation Manager allows columns to be moved inside the window. To

do this, ensure that the Lock Cols button is turned off, then click anywhere in

the grey area at the top of the column to be moved in order to highlight the

entire column. Once this is done click and drag the column to its desired

location.

Setting up the

Results Tabs

The results of the simulations are recorded on the two Results tabs and the

data to be displayed on these tabs should be set up before simulations are

performed. If a simulation is run and the Results tabs have not been set up, no

results are recorded. In this case you would need to run the simulation again

to see values in any new results cells you have added.

The two Results tabs display the list of simulations that have been defined in

the Simulation Scenario tab in the left hand column, and initially display only

one other column with ‘No Selection’ in the top row. As with the Simulation

Scenario tab, when these tabs are subsequently opened they will appear as

last left by the user.

All of the cells in the results tabs are dark grey to indicate that they are

calculated values, and cannot be edited by the user.

Results-Streams

Tab

Parameters are added to the Results-Streams tab, and existing parameters are

changed in the same manner as for the Simulation Scenario tab. The dialog

that appears and which allows the user to select the stream parameter, is

shown below.

In this window the user first selects from drop-down lists the Stream, and

then the Property, Calc Type and the Assay Basis to be displayed. Note that



the Stream drop-down list contains all of the streams in that flowsheet in

alphabetical order. Click on Close to select the parameter. The rows in the data

display header and the Original Data row are automatically filled with values

once a parameter has been selected. The zero values present in some cells are

replaced with simulation results after a simulation run has been performed.

The basis stream for the recovery calculations is selected from a drop-down

list of all of the streams in the toolbar of the Results-Streams tab. Note that if a

different stream is chosen as the basis for the recovery calculation, the new

recovery values calculated using this basis stream will only be displayed after

simulation is performed again.

Results-Equip

Tab

Parameters are added to the Results-Equip tab and existing parameters are

changed in the same manner as for the Simulation Scenario tab. The dialog

which appears and which allows the user to select the equipment parameter

is the same as in the Simulation Scenario tab.

Click on Close to select the parameter. The rows in the data display header

and the Original Data row are automatically filled with values once a

parameter has been selected. The zero values present in some data cells are

replaced with simulation results after a simulation run has been performed.


Using JKSimMet 209

Batch Simulation There are two ways to perform the batch simulations:

1. Simulate Select – used to run only the simulation selected in the

Simulation Scenario tab. This feature enables the user to investigate

the simulated data associated with a particular simulation in more

detail. After running Simulate Select, the user can exit the Simulation

Manager and the streams and equipment in the flowsheet will display

the data associated with the simulation selection. To return the

program to the original data, the user must return to the Simulation

Manager, highlight the Original Data row, then click on the Simulate

Selection button again.

2. Simulate All - as the name implies, this option runs all of the

simulations in the current scenario in the sequence listed by the user.

The program always runs the Original Data simulation after

performing all the simulations defined by the user. This returns the

flowsheet to its baseline conditions so that all streams and equipment

within the flowsheet will have the data pertaining to its original

condition, rather than that of the last simulation. The simulation

scenario data are displayed in the Simulation Manager tables.

Close Window Click on the Close button in the top right hand corner of the window to close

the Simulation Manager window.

Edit Groups The Edit Groups button allows the user to combine equipment units of the

same type and same model together into a named group. When a group has

been defined, it appears in the drop-down list of equipment in the Simulation

Manager, and this allows the user to select the group to change the value of a

parameter for all of the equipment units in the group in one step. For example

in a plant where there are a number of mills, the user could increase the ball

loading by 10% in each of the mills by assigning them to a group and then

setting the % Change for the Load Fraction parameter for this group to 10%.

To create a group the user clicks on the Edit Groups button to display the

Select Equipment for Groups dialog.

Click on the Add Group button to open the Add New Group dialog which

allows the user to create a new group and also to define the equipment and

model types to be included in the group.



Then insert a new column in the Simulation Scenario, choose the newly

created group in the Equipment/Group drop-down list and choose the

parameters in the usual way.

Print Scenario

Grid

Click on the Print Scenario Grid button on the toolbar to print the data

displayed on the active tab. Each tab must be printed separately.

Copy Grid The data displayed in the current tab can be copied to the clipboard by

clicking the Copy Grid button. These data can then be pasted into another

program such as Excel or Word.

Lock Cols Click on the Lock Cols button to lock the current position of the rows and

columns in place. When the Lock Cols button has been clicked, the position of

the rows and columns cannot be accidentally changed.

5.6.3 Accessing the Stream Data

After Simulation, the data associated with a stream can be viewed in the

Streams and Stream data windows. The feed stream data are defined in the

‘Feed’ equipment (see Appendix B2) rather than in the feed stream. This

means that all of the information in the Stream data windows is for viewing

only; no data are entered here.

Accessing the

Stream Data

The Stream window provides access to the Stream data window to view the

data for each stream. The Streams window for each stream can be opened by

three methods:

1. Double-clicking on a stream in the flowsheet.

2. Selecting Stream on the Flowsheet sub menu or

3. Clicking on the Stream icon.


window via the Stream Name drop-down list. The Streams window can only

be accessed when the flowsheet is locked. A typical Streams window is

shown below.

The Streams window also shows the equipment from which the stream

originates and the equipment to which the stream flows. Clicking on the

double arrow buttons next to the From Equipment and To Equipment dialog

boxes opens the Equipment window relating to that equipment. Accessing the

Equipment data is discussed under the heading Accessing the Equipment and

Model Data .193


Using JKSimMet 211

A Typical Streams Window

The Stream data window is accessed by clicking on the double arrow button

next to the selected stream. The stream name of the stream being viewed is

displayed in the header of the Stream data window. Once this window is

opened, the layout and the actual data on display can be changed to suit your

requirements (see below).

Stream Data

Window Layout

The layout of the Stream data window is the same for every stream. A tabbed

interface is used to display the different types of stream data. The Totals,

Sizing data, Elemental assay data and Size by elemental assay data tabs are

always displayed.

The types of data available to view in each tab include simulated,

experimental, balanced, SD, error and fitted, and can be selected by clicking

on the Data Type View button. Unwanted data types can be turned off by

selecting the selecting ‘None’ in the appropriate column.

A typical Stream data window is shown below. In this case, all data types

other than Sim have been switched off.

A Typical Stream Data Window

Totals Tab The Totals tab is always displayed, and lists the overall properties of the



stream. The values in the Totals tab for each stream are calculated during

simulation. Note that the values in the Totals tab for the feed stream are

defined in the Feed equipment.

The other tabs and the data displayed are:

Name of Tab Data Displayed

Sizing data Size fractions and the proportion of the

stream in each size fraction

Elemental assay data Elements and the proportion of each

element in the stream

Size by elemental assay data Proportion of each size class that is

made up of each element

Note that in JKSimMet, the last two tabs are not relevant for simulation. One or

both of these tabs will only become relevant and of interest when you are

looking at the results of a mass balancing operation.

5.6.4 Water in Simulation

There is a selection of models available for water feeders. To associate an

appropriate model with a water feeder you need to double click on the water

feeder icon, just as you would do for any other equipment type. This will bring

up the water feeder Equipment window. From here you select the required

model using the Equipment Model drop-down.

In this case we will select the Required % Solids model for both of the water

feeders. Once the model has been selected, you can click on the double arrow

button to the right of the drop-down to set the parameters associated with this

model.


Using JKSimMet 213

In the case of the Learner Project, the required % solids should be set to 75% for

the BM Water feeder and 35% solids for the other water feeder (the one adding

water to the cyclone feed sump).

A detailed description of the Water Feeder models can be foundunder Model Descriptions.

Remember:

Select the two water feeders from within the Select Equipment / Streams frame

and then select "Adjust" for TPH water within the Control frame of the Mass

Balance sheet.

5.7 Viewing the Data - Summaries & Reports

To view the summary table of the stream data the user the user will need to

access and configure the Configurable Stream Overview.

5.7.1 Using the Configurable Stream Overview

An alternative to entering data individually into the stream windows is using

the Configurable Stream Overview. This is recommended when the data is

initially configured, or can be configured, into a similar style table in Excel

and simply copied and pasted into JKSimMet.

Configurable

Stream

Overview

The Configurable Stream Overview can be selected from the flowsheet menu,

or launched by the icon on the flowsheet toolbar.

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Configurable

Stream

Overview

Window

The Configurable Stream Overview window has several main components:

1. Select List drop-down list

2. Configurable Stream Overview toolbar

3. Data view choice drop down

4. Button to launch the SD calculation window

5. Data table

Select List The user can create one or more Configurable Stream Overview tables. Each

table created is listed by name in the Select List drop-down, allowing the user

to change from one table to another by selecting the required configuration

from the list.

Configurable

Stream

Overview

Toolbar

The toolbar allows the user to create new configurations, rename or delete

existing configurations, add or delete rows and/or columns, print, copy, clone

or export the data to Excel.

New Stream

Overview

To create a new configuration the user clicks on the New Stream Overview

button. This opens the Add New Stream Overview dialog which prompts the

user to enter a name for the new configuration.

Delete Overview Clicking on the Delete Overview button deletes the current overview. A


deleted, as this operation cannot be undone.

Insert Column This button will insert a blank data column to the right of the column where

the cursor is currently located. To select a column, click inside the column

itself, not on the column header. Clicking the column header will open the

Selection Options window where you determine the contents of the

column in question.

Copy Column Pressing this button will insert an extra column that will be a copy of the

currently selected column. You can use this if the new column is to be similar

to the previous one. For instance you could copy a column containing

experimental data and just switch the data type in the copy to simulated data.

Remove Column Removes the column where the cursor is currently located. Note that the

column is deleted immediately without the user being asked to confirm their

action.

Insert Row Inserts a stream data row in the overview table, in the row below the current

position of the cursor. When the button is clicked the Add Stream dialog

opens, requiring the user to select the stream to be added to the table from the

list of streams that are not already displayed in the table.

217

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Using JKSimMet 215

If no streams are listed in the dialog, it means your table already contains all

the streams from this flowsheet and therefore no further rows can be inserted

in this table.

Remove Row Pressing this button removes the currently selected row from the table.

If necessary, the deleted stream can be added back into the table using the Add

Row button.

Print Overview Prints the current overview table.

Copy Grid Copies the entire data grid for the current overview to the clipboard, allowing

the data to be pasted into other programs such as MS Word.

Lock Move

Rows/Cols

When this button is unlocked (appearing as shown in image at left) the user is

able to change the position of rows and columns of data.

Export Overview This button exports the data for the current overview to Excel. Clicking on the

Export Overview button opens the Export Report to Excel dialog where the

user can enter a name for the Excel file and choose where to save the file. Note

that if the file name chosen is the same as an existing Excel workbook, the user

is prompted to choose whether to overwrite the existing workbook or to

append the current data as a new worksheet in the existing workbook. The

name of the Overview that you have just exported will be adopted as the name

of this new worksheet.

Export All Selecting Export All will export all of the overviews listed in the Select List

drop-down to Excel, with each one occupying a separate named sheet in the

Excel workbook.

Clone Overview Clone Overview creates a new overview, which will be an exact copy of the

current overview. This option is useful when viewing or inputting data for

the streams on a sized basis and more than one similar overview screen is

required.

Creating a new

Configurable

Stream

Overview

When the user clicks on the New Stream Overview button the default data

table is displayed. As shown below, this lists all of the streams in the

flowsheet, and displays the TPH Solids (Sim) and TPH Water (Sim) values for

each of the streams.



The Default Configurable Stream Overview Layout

Adding Streams

to the Table

To add a stream to the overview table click on the Add Row button and select

the required stream from the list shown in the dialog.

Changing the

Stream Order

The order that the stream names appear in the table is the order in which the

streams were added to the flowsheet when it was first drawn. To change this

order unlock the Lock Move Row/Cols button and then select a stream in the

data table by clicking in the stream name cell and then drag the row to its new

location on the list as indicated by a red line. Two or more adjacent stream

rows can also be moved by selecting all of the rows together (click and drag or

Shift-click) and dragging the group to their new location in the table.

Removing

Streams from the

Table

To remove a stream from the overview table click in the row which is to be

removed and click the Delete Rows button.

Setting Up to

Enter

Experimental

Data via the

Overview

It is possible to enter your experimental data via the Configurable Stream

Overview window. To do this you need to select 'Experimental' as the type of

data from within the Selection Options dialog box.

Clicking on the header cell in each column of the Configurable Stream

Overview window will bring up the Selection Options window, an example

of which is shown below. In this window you need to select the parameter, the

calculation type and the data type that are to be displayed in the column you

are configuring. Normally these are selected from the Options 1, 2 & 3 drop-

down lists respectively.

The various data types available (Option 3 listing) are as follows:

Experimental – Displays experimental values.

Standard Deviation – Displays standard deviations.

Simulated – Displays simulated data.

Fitted – Displays the fitted values (following the run of a simulation).

Balanced – Displays mass balanced data following the running of a mass

balance.

Error – Displays error data.

Note that the above is the full list of data types. This will sometimes be


Using JKSimMet 217

reduced, depending on the selections that have been made from the Option 1

and Option 2 drop-down lists above.

For preparing a column that is to be used for the entry of your raw data, you

need to select 'Experimental' from the data type (Option 3) drop-down. The

example below shows a situation where the user has chosen to display

elemental assay data for copper and has selected experimental as the data

type.

On returning to the Configurable Stream Overview, you will find that data can

now be entered into this column for the various streams that you have set up

in this particular overview and that this will also be the case for any further

streams that you may later add to this overview.

Configuring the

Columns

The configuration of a new columns is covered in greater detail in the next

topic.

5.7.2 Configuring Columns in the Stream Overview

Configuring a

New Data

Column in the

Overview

When a new column is added to the Configurable Stream Overview table by

clicking on the Insert Column button the added column is headed 'No

Selection' and contains no data. The user must select the data to be displayed

in the column by first ensuring that the Lock Move Rows/Cols button is locked

and then single clicking on the header cell for the column. This opens the

Selection Options dialog.



The user can select the required property, calculation type and data type from

the drop-down lists in this dialog. You will see as you start making selections

from the Options drop-downs, that the items available in each will always

depend on what has been selected from the preceding drop-downs. As you

will soon realise, there are a lot of permutations possible, so in this topic we

will just look at a couple of examples. In the examples selected, the user is

presented with quite a few choices before arriving at the complete

specification of the data to be displayed in the column being configured.

Option 1

Selections

In the first drop-down list (labelled Option 1), the items available for selection

are as shown below:

Difference

between %

Passes and %

Passing Data

If you select % Passing you will be presented with a data entry dialog where

you can type in the size (in mm). The data will then relate to the proportion of

the particles that are smaller than your chosen size. In the illustration below,

the user wishes to see data relating to the % of the ore particles that are finer

than 0.25 mm.


Using JKSimMet 219

If you select % Passes, then you are requesting data in the form of the screen

size that a given percentage of the particles will pass. In this case you are

again presented with a data entry dialog, but this time what you are entering

is a percentage value rather than a size.

In the illustration above, we are setting up the overview table to display data

relating to the 50% passing size for each of the streams in our flowsheet. Note

that one of the other options in the Option 1 drop-down is P80. Selecting this

item will generate the same type of data, but in this case the 50% value entered

above is replaced by the standard 80% value. Obviously in this case there is

no need for the % Passes data entry dialog, so this will not appear.



Elemental Data

for the Option 1

Selection and

Subsequent

Choices

If you select Elemental from the Option 1 drop-down, you will then generate a

further selection dialog box where you have to choose the particular element

that you wish to retrieve the data for. Of course this is only relevant for mass

balancing in JKSimMet since none of the JKSimMet models deal with the

distribution of elements around the flowsheet.

Once you have selected the element required, the Option 2 selection drop-

down will require you to select between the options TPH, Assay and

Recovery. If you select either TPH or Recovery, the Option 3 alternatives will

be Experimental, Balanced and Size.

If you select Assay from the Option 2 drop-down, the situation becomes a

little more complex, with more options available as shown below.

In this case if you now select Size, you will get a dialog for selecting the size

that you wish to obtain data for.


Using JKSimMet 221

Once this selection of the required size has been made, the Option 4 drop-

down will become available where you can then select which type of size

related elemental data is to be displayed. In the case below we are selecting

Error data for copper assays in the +0.6 mm size fraction.

Be Sure to Select

Exp vs Bal Error

Data if

Elemental Data

Selected

Selecting Error from the above list then requires you to make another choice

regarding the type of data to be compared for the error determinations. Note

that although at this point you can select from the 5 options available in the

dialog box shown below, only the first option of Exp vs Bal will yield any data

when you return to the Configurable Stream Overview table. This is again due

to the fact that we are dealing at this point with elemental data so there will be

no simulated or fitted data for use in the error calculations.



Once you make this selection, another dialog will appear for selecting the

error calculation method.

Here you can select whichever type of error you wish see displayed in the

Configurable Stream Overview table. Assuming in this case you wanted to

display the weighted errors, then after pressing OK, the Selection Options

dialog would look like the one shown below.

94


Using JKSimMet 223

Error Sum for

the Option 1

Selection and

Subsequent

Choices

If you select Error Sum for Option 1 (last item on the list), you will be presented

with a dialog box for selecting the type of errors that are to be summed. A screen

grab of this dialog box is below. In this instance, all 5 options are meaningful

since we have not at this stage narrowed the selection to elemental data as we had

in the case described above.

After you have selected the types of data are to be compared to give the individual

data point errors, you will next be presented with a dialog for selecting the type of

error calculation used to arrive at error values for each of these data points. The

choices here are weighted error, percent error and absolute error. The way these

errors are calculated is explained in the topic Viewing Individual Stream Data

.

94



If you have selected Exp vs Bal from the list of data type comparisons (see the

second last screen grab), then you will be presented with a further choice

regarding the circuit parameter errors that are to incorporated into the error sum.

Note however, that you will only be presented with the above selection drop-box

in JKSimMet if your selection of data types for comparison is Exp vs Bal. The last

two possibilities for inclusion in the error sum are not relevant if you selection

includes simulated or fitted data as the distribution of elements throughout the

flowsheet is not modelled in JKSimMet.

Your selections from these three dialog boxes will be concatenated into an

automatically assigned name for the overall Option 1 selection. This name

appears in the display box to the right of the Option 1 drop-down. As can be seen

from the screen grab below, this name can be rather long and in fact doesn't fit

into the display area in this case.


Using JKSimMet 225

When you press OK on the above dialog box to close it, the column you have been

setting up in the Configurable Stream Overview will now have this name as its

header. The automatically generated name for the error sum makes the column a

lot wider than it needs to be to accommodate the data (see below).

Modifying

the Column

Names

To overcome this problem, there is the facility to make your own abbreviation or

acronym for the type of error sum that has been selected. To do this you simply

uncheck the Auto Generate Name check-box and replace the auto generated name

with an acronym or abbreviated name that will make sense to you. This can be

done before or after you have gone through the Options selection sequence.



In this case one might abbreviate the above error sum descriptive name to ErrS

(EvB W T&S) to make the column width closer to that needed for display of the

numbers themselves. To illustrate this, a second column with the same data but

with the abbreviated error sum header, has been included in the screen grab

above.

Note that this ability to insert your own name for the column headers is available

for all of the other data type options as well. It has been illustrated for the error

sum data type as this is where the auto generated name ends up being the longest.

5.7.3 Using the Reporting Feature

The Reporting feature is the main means for exporting data from JKSimMet. By

using this feature the user can export the data to Excel for printing or further

analysis

Overview The reporting functionality is accessed either from the flowsheet menu or from

the reporting icon on the flowsheet toolbar.

Reporting to

Excel Window

The Reporting feature allows the equipment and stream data to be exported to

Excel. The user can select which equipment units and which streams have

their data exported. Each report configuration is named by the user when it is

created and this allows the user to create multiple report configurations.

Reporting to

Excel Toolbar

The toolbar allows the user to create new configurations, delete unwanted

configurations, select or de-select data in the selection list and export the data

to Excel.


Using JKSimMet 227

New Report To create a new Report configuration the user clicks on the New Report

button. This opens the Add New Report dialog , allowing the user to name the

new report configuration.

To generate a report the user can either choose to use an existing report, or

create a new report. To create a new report the user will need to:

1. Add a report to the system

2. Select the format of the report

3. Choose whether to summarise the report data

4. Select which equipment units and streams are to be used in the report

5. Choose which data types to export

6. Choose whether to use a circuit select list

7. Choose to export port data



8. Export the data

Report Name

List

Each report configuration created is listed by name in the Report Name drop-

down list, allowing the user to maintain as many report configurations as

they require.

Delete Report Clicking on the Delete Report button deletes the current configuration. A


deleted, as this operation cannot be undone.

Export Report Exports the selected items on the reporting dialog to an Excel workbook.

Format of the

Excel Workbook

The Excel workbook created by the Reporting to Excel feature displays the

selected data in a standard layout. The user is then free to format the data in

the report as they choose.

Part

VI



6 Mass Balancing

Mass Balancing This section provides information about the mass balancing capabilities of

JKSimMet V6.

6.1 Introduction to Mass Balancing

Purpose This chapter describes how to use the JKSimMet mass balancing component

of the software.

Overview Even the most carefully collected plant survey data are subject to many

sources of variation. Some of these errors are generated within:

• the natural variation in process flows, assays, etc.

• sampling procedures or design

• assaying procedures

• sizing procedures

• fluctuations in plant flow rates, operating variables, feed parameters, etc.

As with all data improvement processes, the usefulness of the mass balanced

data will be strongly dependent on the quality of the input data. The mass

balancing module can assist the user to assess data and to refine their

experimental technique when problems are detected. Mass balancing will

improve the quality of good data. It will not fix poor quality data or do

anything more than highlight inadequate experimental techniques.

The module is used to mass balance sizing data, head assay data, assay data

in size classes and flow rate data collected at steady state. The balancing

process produces best fit estimates of flow rates, size and assay data which

are consistent within the mass balancing constraints.

The overall process is:

• Collect data, using appropriate sampling methods (see Gy (1982), etc.)

• Review data

• Mass balance data,

• Check accuracy of data fit and

• Refine experimental technique and instrumentation until desired level of

accuracy is obtained.

6.2 Data Collection

Good data collection procedures are essential to the success of a mass

balance. While this section is not essential for learning how to use the mass

balancing program, it should be studied in detail as poor data collection will

have a significant impact on the quality of mass balance that can be achieved.

Flow Rates Numerous flow rate measurements are very useful. Hence, calibration of all

flow measurement devices (weightometers, flow meters, etc.) is important.

Whenever possible, try for an independent flow rate check. In small or pilot

plants, time and weigh a known volume of material. As a minimum

Version 6.0.1 - March 2014 Data Collection

Mass Balancing 231

requirement, the feed tonnage to the circuit is required.

Percent Solids The percent solids of a slurry as measured with a Marcy scale are subject to

error, due to solids density variations in the circuit. Such variations are

common in cyclone underflow streams. Therefore, percent solids determined

from wet and dry sample weights are preferred.

Steady State JKSimMet is a steady state simulator. Hence, models can most usefully be

fitted to data which were taken at steady state. The most common approach is

to take a series of regular samples and combine them to make composite

samples which cover a period which is long (several hours) compared with

circuit fluctuations, which must be kept to a minimum.

If circuit variations are a serious problem, sample and fit one process unit at a

time. JKSimMet can be used to combine the units and predict circuit steady

state behaviour.

Sampling Good sampling practices are a topic in themselves. Some useful references are

those of Gy (1982) and Lyman (1986) .

For a simple estimating technique for sampling requirements refer to the paper

by Lyman (1986).

There are well established rules for calculating the accuracy of a sampling

and assay process. These can be used to establish an error model which can

then be used to provide estimates of standard deviation for each point.

Alternatively, 5 to 10 replicate samples can be taken and processed. If these

input accuracies are established, then the estimates of accuracy used for flow

rates and assays will be real estimates and not relative estimates.

If replicate sampling is carried out for assays on a number of streams (i.e. a

range of assay values), a simple two term error model can be generated by

plotting relative standard deviation against average assay values from each

stream.

The intercept and slope of this plot will provide fixed (minimum) and relative

(%) error components which can be used in the generalised version of the

Whiten model.

A sensible maximum (absolute) error will also need to be specified.

Determining good estimates of the errors associated with each sampling point

will provide a more reliable mass balance.

6.3 Background

Mass Balancing is a type of model fitting. The models in this case are quite

fundamental. Hence, they do not impose the experience knowledge (which is

built into other mathematical process models) onto the data.

The mass balancing models are:

a stream combiner (for example, a pump sump),

a general stream splitter (for example, a hydrocyclone or a flotation

cell),

a unit that conserves some properties but not others

(for example, a grinding mill will preserve total assays and flow rates but not

269

Version 6.0.1 - March 2014Background


size fractions).

The basis of the mass balancing algorithms is the differences in composition

of various streams; that is, the differences generated by the process equipment.

Consider a process with these streams having assays a, b, c:

If the solids flow rate in a stream of assay "a" is 100 tph, then:

(1)

where x is the solids flow rate in stream of assay "b" and then:

(2)

This is the basis of the traditional two-product solution, where a, b and c may

be assays for a size fraction, element or any other conserved property.

It does not matter what kind of assays a, b and c are, as long as there is some

difference in their values. For example, if the process is a splitter and the

assays are all the same:

a = b = c

and therefore, using equation (2), then x= 0/0 which is undefined.

Expressed another way, the flow rates can be estimated only if a process

imposes a difference on its products; that is, some information is imparted by

the process. If no information is imposed, as is the case with a splitter, then

the information cannot be used to make estimates, as it is not there to begin

with. Note that the split ratio of a splitter can be used in the mass balance.

It follows that the most useful properties to use for mass balancing around a

process unit will be those which have the largest difference in the product

streams.

This means that size assays will work well around a size classifier such as a

screen or a hydrocyclone, and elemental assays will work well around a

flotation circuit. The reverse will generally not be true, with some notable

exceptions. For example, elemental assays such as gold or lead are often very

useful around a hydrocyclone classifier because its density-separating

characteristic will usually produce a large difference in these assays.

The power of this program lies in its ability to use a wide range of assays

across a large flowsheet. The program algorithm is driven by the assays with

large differences but still takes account of those with small differences.

Concept: Mass

Balancing

The mass balancing module takes all selected streams and calculates the

smallest set of data adjustments which will make the data consistent.

If some (or all) of these streams are measured (sampled and sized, etc), the

experimental measurements can be compared with the data. The root mean

square of the normalised differences between measured data and adjusted

Version 6.0.1 - March 2014 Background

Mass Balancing 233

data is taken as a measure of goodness of fit of the model.

i.e.

Hence, the mass balancing program adjusts user selected flow rates to find a

best set of flow rates which make the balance output match the experimental

measurements as closely as possible.

Concept:

Weighted Sum

of Squares

If the precision of each data point is measured (or can be estimated from

experience), then each difference between experimental data and mass

balanced prediction is normalised by dividing by its precision. That is, a

small difference (or adjustment) between an accurate data point and its mass

balanced prediction will make the same contribution to the weighted sum of

squares as a large difference from an inaccurate data point.

Concept:

Standard

Deviation

The usual measure of precision is the standard deviation. If repeated

measurements are made of any data point, experimental variations will cause

variations in the measured value xi.

Then with many repeats, the mean of the values will provide an estimate of

the true value of x.

Subject to a number of assumptions, the expected variations from true x can be

characterized by one number - the standard deviation defined as:

Standard

Deviation

If the measurements are normally distributed then, out of 100 measurements,

67 could be expected to lie within plus or minus one standard deviation of

the true value (as estimated by the mean), 95 within plus or minus two

standard deviations and 97 within plus or minus three standard deviations.

Concept:

Estimating

Standard

Deviation

Experimentally, 5 to 10 complete observations, that is, independent sampling

plus analysis, will provide an estimate of the standard deviation. The mean

of such a set of measurements should provide a good test of sampling

precision - if the test circuit was at steady state.

Concept: RMS

(Root Mean

Square) Errors

As its name suggests, the RMS (root mean square) error is the square root of

the residual mean square error, which is the error associated with the

calculated mass balanced data and the experimental data.

A root mean square error of value 1 means that all data points were estimated

with errors similar to the measured standard deviations of the experimental

data points. Obviously, the more the RMS error varies from one, the more error

is associated with fitting the data.

6.4 How the Mass Balancing Program Works

The mass balancing program used by JKSimMet is a program called

JK2DMBal written and developed by Dr Stephen Gay. Other JKMRC staff,

including Michael Andrusiewicz, Jake Stoll, Ricardo Pascual and Robert

Lasker, provided assistance with the integration of JK2DMBal into the

Version 6.0.1 - March 2014How the Mass Balancing Program Works


JKSimMet program.

The mass balancing problem is essentially a minimisation of sum of squares

with multi-linear constraints. This corresponds to a common set of

mathematical problems generally described as the ‘quadratic problem’.

The algorithm is based on a Quasi-Newton approach which means that the

errors in the constraints are used to determine the changes required in

calculated variables, with the amount of movement of the calculated variables

controlled by the standard deviations of the experimental values.

Hence standard deviation values of 0 mean that a calculated value will equal

the experimental value and will not change. If all the standard deviations are

near 0, the program will not have enough freedom to find a solution, and

therefore will not converge. The JKSimMet standard deviation interface

provides formulae to allow appropriate standard deviation values to be set.

When a plant is surveyed, size and assay information are often obtained, as

well as percent solids. However, the solids flow is only known for a small

number of streams (and in some cases, the feed stream only). Very high

standard deviation values imply that the corresponding experimental value is

unreliable. Hence, large standard deviation values are often used for the

solids flow values.

The main algorithm (Quasi-Newton algorithm) needs reasonable starting

values of solid and water flow in order to converge satisfactorily. In order to

estimate these flows (principally where experimental values are not given), a

second algorithm is used.

This second algorithm uses information such as assays and size distribution

data to estimate solids flows. This algorithm is very similar to the method

described as the Morrison solution in JKSimMet. The main difference is that it

also uses the standard deviations of the assay and size information, and it

provides an estimate of the standard deviation of the estimated solids flow.

If there are many missing streams, or missing data, the algorithm will still

have some difficulty in obtaining a solution as the standard deviation values

are too high. A third algorithm is used to reduce the standard deviation

values as the algorithm proceeds to ensure that convergence is obtained.

The three algorithms (Quasi-Newton, missing flow estimation and variable

standard deviation reduction) are all integrated together within the one

algorithm interfaced to JKSimMet. Even though the algorithms work together

it still remains that in some circumstances data reduction may be required to

improve performance. For example, if there are many missing solids flow

values it is best to mass balance solids flow first with information such as

sizes and head assays prior to mass balancing assays within size classes.

JKSimFloat has a hierarchy of data associated with the mass balancing

algorithm. This hierarchy has the solids mass flow at the top, with head

assays, size fractions and % solids all subordinate to the solids mass flow.

The assays of size fractions are subordinate to size fractions, and the mass

flow of water is always a bottom level measurement.

This can be represented schematically by the following diagram.

Version 6.0.1 - March 2014 How the Mass Balancing Program Works

Mass Balancing 235

6.5 Learning Mass Balancing

The mass balancing module of JKSimMet is useful in two areas. Firstly, it

provides a check on data accuracy that is not model dependent. The mass

balancing models are correct (that is, they contain no built in experience).

Hence, if the data balance well but the model fitting does not fit well, it

indicates that the model is not appropriate.

Where coarsely sized samples are used, as in crushing and screening circuits,

the mass balanced data may be more useful as the starting point for model

fitting than the raw data.

Secondly, mass balancing is useful for determining flow rates and recoveries

around complex circuits. The example we will use in this section, Learning

Mass Balancing, is concerned with flow rates in the comminution circuit of a

copper concentrator.

Normal

Sequence for

Mass Balancing

in a

Comminution

Circuit

It should be noted that JKSimMet V6 provides the ability to balance assays

within size classes as well as total assays and sizes. Unlike V5, the user does

not balance everything at once. Under the assumption that in a comminution

circuit your sizing data will be the most reliable survey data, the suggested

process to balance a whole circuit is as follows:

1. Make selections for all required equipment, streams, sizes and

elements.

2. Set TPH Solids and Sizes to Adjust and all other components to

Unused, then run the balance.

3. Then set the TPH Solids and Sizes to Fixed, the TPH Water to Adjust

and % Solids to Influence and run the balance again.

4. Set the TPH Water and % Solids back to unused and the Elements to

Adjust and run the balance again.



The individual steps will be covered in more detail over the remainder of this

chapter.

Version 6.0.1 - March 2014Learning Mass Balancing


Mass Balancing

Sequence where

Assay Data is the

Most Reliable

Data

In cases where your assay data is considered more reliable that the sizing

data, you would modify the above sequence as follows:


elements.

2. Set TPH Solids and Elements to Adjust and all other components to

Unused, then run the balance.

3. Then set the TPH Solids and Elements to Fixed, the TPH Water to

Adjust and % Solids to Influence and run the balance again.

4. Set the TPH Water and % Solids back to Unused and the Sizes to

Adjust and run the balance again.

5. Set the Sizes to Fixed and Size x Element to Adjust and run the


Mass Balancing

Sequence where

% Solids Data is

the Most

Reliable Data

In cases where your % solids data is considered the most reliable data, you

would be better using the balance sequence below:


elements.

2. Set TPH Solids and TPH Water to Adjust and % Solids to Influence

and all other components to Unused, then run the balance.

3. Now set the TPH Solids to Fixed, TPH Water and % Solids to

Unused and the Sizes to Adjust and run the balance again.

4. Set the Sizes to Fixed and the Elements to Adjust and run the

balance again.



6.5.1 Model Types for Mass Balancing

In V6.0.1 of JKSimMet the flowsheet drawing for mass balancing is the same

one used for simulation and model-fitting, with the full range of equipment

icons available to draw the circuit diagram. However, no matter what

equipment icon is visible, there are only two model types in mass balancing.

These are:

classifier or mixer unit

This unit either selects particles to go to different product ports of

the unit (classifier) or adds particles from different feeds (mixer).

That is, particles are sorted or mixed in this type of unit, not

broken down or altered.

transform unit

In this unit assays are preserved but size structures are destroyed.

In mass balancing all comminution devices are transform units.

The mass balance algorithm decides which type of mass balance unit is

required according to the flowsheet icon selected by the user.

Version 6.0.1 - March 2014 Learning Mass Balancing

Mass Balancing 237

6.5.2 Entering the Data

Data Entry

Alternatives

The first step in a mass balancing exercise is to enter the experimental data.

This can be performed in two ways:

Individual Stream data windows, or

Configurable Stream Overview

Both methods have their advantages and disadvantages; it is mainly

dependent on what form the experimental data is in.

Accessing the

Individual

Stream Data

The Streams window provides access to the Stream data windows to view the

data for each stream. The Stream data window for each stream can be opened

by three methods:

1. Double-clicking on a stream in the flowsheet.

2. Selecting Stream on the Flowsheet sub menu or

3. Clicking on the Stream icon.


window via the Stream Name drop-down list. The Streams window can only be

accessed when the flowsheet is locked. A typical Streams window is shown

below.

The Streams window also shows the equipment from which the stream

originates and the equipment to which the stream flows. Clicking on the double

arrow buttons next to the From Equipment and To Equipment dialog boxes

opens the Equipment window relating to that equipment.

The Stream data window is accessed by clicking on the double arrow button

next to the selected stream. Once the Stream data window has opened, the user

can view the various categories of data by selecting the appropriate tab. The

name of the stream being viewed is displayed in the header of the Stream data

window. The Streams window remains open and accessible after the required

Stream data window has opened. If you then select another stream from the

drop-down and click again on the double arrow, you will open a second Stream

data window for the new stream. You can open as many Stream data windows

as you require in this way.

A typical Stream data window is shown below.



The status of the stream can be set to ‘Major’, ‘Minor’, or ‘Missing’ from the

drop-down box at top right. See later in this help file for an explanation of

these terms.

Totals Tab The Totals tab lists the overall properties of the stream. The other tabs and the

data displayed are:

Name of Tab Data Displayed

Sizing data Size fractions and the proportion of the stream in

each size fraction

Elemental assay

data

Elements and the proportion of each element in

the stream

Size by elemental

assay data

Proportion of each size class that is made up of

each element

Data can be inserted into the individual stream windows using the copy and

paste functions from Excel.

Sizing Data If you click on the Sizing Data tab you will here be able to enter the sizing data

for the size fractions that have been defined for this project and the associated

SD values. The Stream data window will then look similar to the one shown

below:

248


Mass Balancing 239

The above window will also show balanced values from the most recent

balance, provided the balancing engine has been run at this point.

Elemental

Assay Data

The next tab is for the elemental assay data and the appearance of this window

will be similar to the one shown below when this tab has been selected.

The last tab is for size by elemental assay data and a screen grab of the

appearance with this tab selected is shown below:



In this case the numbers are all zeros since no sizing data have been entered at

this point.

Configurable

Stream

Overview

An alternative to entering data individually into the stream windows is to use

the Configurable Stream Overview. This is recommended when the data has

been initially configured into a similar style table in Excel. Such a table can

then simply be copied and pasted into JKSimMet.

Click on the Configurable Stream Overview icon or select this item from the

Flowsheet menu to open the Configurable Stream Overview window. You

may need to create a new overview that will have the data in the same order

as it is structured within the Excel source file. Alternatively you could

manipulate the setting out of the Excel file to match a structure you have

previously created within the Configurable Stream Overview. For more

information on how to make changes or create new Stream Overviews, you

should revise the topic Using the Configurable Stream Overview .

6.5.3 The SD Calculation Window

SD

Calculation

Window

From the Stream Data window, the Automatic SD Calculation window can be

opened by pressing the SD Calculation (SD) button which is the button second

from the left on the Stream data window toolbar.

From here you can specify numerous different methods of automatically

calculating SD values for the various experimental data fields.

263


Mass Balancing 241

More detail on how to set the options for SD calculation are covered in the Stream

Windows topic, in the Using JKSimMet section.

The data types associated with the other default columns are simulated (Sim),

fitted (Fit), balanced (Mbal) and the error (Err).

Selecting

the Type of

Error

Calculation

In the case of the error column you can change the form of the error that is

displayed and the currently selected form will be shown in the column header.

This is done by clicking on the Error Sum button, which is the button second from

the right on the Stream data toolbar.

After pressing this button, the Error dialog box will appear where you can specify

both the types of data that are to be compared for determining error values and the

method by which these errors are calculated. For instance in the settings shown in

the screen grab below, the errors will be obtained by comparing the experimental

and balanced data and the method of calculation will just be a straight percentage

error calculation.

165



Also in this screen grab, you will notice there is a frame labelled Error Sum below

the drop-down selection boxes. Here there are radio buttons where you can select

the errors that are to contribute to the calculation of the error sum figure that is

displayed in a field (shown circled below), at the top of the Stream data window.

Note that it is only when you select Exp v Bal data for comparison that all three

options are available for the error sum calculation. Because JKSimMet does not

contain models that predict element distributions, the last two options cannot be

selected where either Fit or Sim data are one of the data types to be compared.

These options will be greyed-out in all but the Exp v Bal data case.

Error

Calculation

Methods

and

Summing of

Errors

The types of error calculation available for selection are Weighted, Percent and

Absolute. Weighted errors take account of the reliability assigned to the various

data points by dividing the difference by the SD value. Larger SD values mean that

the differences will contribute less to the total error calculation. The other two

methods take no account of the assigned SD values.

The calculation methods are:


Mass Balancing 243

Weighted errors are calculated as [(Exp - Bal)/SD]2

Percent errors are calculated as Abs[(Exp - Bal)/Exp] * 100

Absolute errors are calculated as just (Exp - Bal)

In the case of the first two error calculation methods, the individual errors are

always going to be positive values. Thus to obtain the error sum in these two cases,

the individual values are simply totalled.

For the Absolute error values though, there will be negative values displayed for

some data points and positive ones for others. To make these values all contribute

to the total error and do not tend to cancel each other out, in this case it has to be

the modulus of each value that gets incorporated into the Error Sum calculation.

6.5.4 Standard Deviation Calculations

All Data Points

Require

Standard

Deviations

Every data point must have a standard deviation entered, even if it is

‘Missing’. During the mass balancing routine, if any data point has ‘0’ as it’s

standard deviation, an error message will be displayed with an option for the

user to enter the correct SD.

Standard deviations can be entered individually in the stream data windows,

or through the Configurable Stream Overview window. They can also be

copied and pasted from Excel.

Entering a standard deviation in the individual stream data windows is

particularly useful if, for instance, no experimental data for a particular

stream exists. The procedure for this is outlined below.

Entering

Individual

Stream Standard

Deviations

Ensure the flowsheet is locked and double click on a stream to bring up the

stream window for that stream.

If the sample or flow data for a particular stream is not available, you can

leave the experimental value set to zero and then set the standard deviation

value to ‘Missing’.

Setting the SD to

Missing

If ‘missing’ is entered for the standard deviation, the mass balancer will

recognise that no experimental data was recorded for this stream. However,

the stream will be included in the mass balance and a balanced value will be

263



generated using the rest of the data set.

For an initial pass, the actual stream can be omitted from the balance routine,

rather than setting the SD values to ‘missing’. This will not make much

difference in a simple flowsheet, but may speed up the balance in a more

complex one.

Alternatively, if experimental data exists for that stream and the standard

deviation is known, it is possible to enter that standard deviation directly in

this window. Simply click in the appropriate cell of the ‘SD’ column and type

in the standard deviation. Press ‘Enter’ when complete.

It is also possible to copy and paste standard deviation values from Excel into

the individual stream data windows and the Configurable Stream Overview

window.

The Automatic SD Calculation window allows the user to set SD values for

multiple streams and data points simultaneously. This is accessed by the SD

Calculation button in both the individual stream window and the

Configurable Stream Overview windows.

Entering

Standard

Deviations for all

Streams

The Automatic SD Calculation window appears as follows.

The left-hand panel lists all the streams in the current flowsheet. Individual

streams can be selected by clicking on the stream name. Multiple streams can

be selected in a similar manner to the way this is achieved when using

Windows Explorer. A contiguous group of streams can be selected by holding

<Shift> when clicking on a stream further down the list. A selection of non

contiguous streams can be made by holding down <Ctrl> and clicking on the

streams required.

The “Property” drop-down permits the user to select the parameter that is to

have the standard deviation formula applied to it. To select a property, click

the drop-down arrow and double click on the desired property.

The “SD Calculation Option” drop-down allows the user to choose from a list

of mathematical formulae and other options for setting the standard

deviations. This list contains the following formula options: Bounded

percentage, Parabolic, SD Multiplication Factor, Exp Val Multiplication


Mass Balancing 245

Factor, Replacement Value and Missing Value.

If you tick the check-box labelled “Include SD values currently set to

missing?” the program will take the experimental value for the stream and

will apply the selected SD calculation to this value. If you do have some of the

SD's set to missing, then it is likely that the experimental values for these

would have been zero. Where this is the case, the value that goes into the SD

field will depend on the SD calculation method selected. If you have selected a

method that involves just a fraction multiplied by the experimental value, then

obviously you will get an SD value of zero. This will mean that when you run

a balance involving these parameters, you will get an error message and be

requested to give the offending SD's some values other than zero. If you

choose another SD calculation method (such as Whiten), where a non zero SD

value will be the result, there is still a problem with balancing because the

balance engine will be trying to accommodate a zero value whereas the actual

experimental value (if a sample had been taken) would no doubt be well

removed from zero. So if you are going to place a tick in this check box, make

sure you have some guessed values in the experimental value fields and that

you are setting a large SD on these values.

There are also some default values that have been pre-set to enable rapid SD

calculation:

Fixed : SD = 0.001

Poor : SD = 20% of the experimental value

Average : SD = 10% of the experimental value

Good : SD = 5% of the experimental value

Excellent : SD = 2% of the experimental value

These values can also be changed if necessary in the Automatic SD

Calculation window.

Note that although this facility allows you to use relative SD's as a quick way

of setting up the balance, their use is not generally recommended because a

balance using relative SD's takes most notice of the smallest assay values and

these are often the least well defined.

Bounded

Percentage

When the Bounded Percentage option is selected, the user inputs the Upper

(U), Lower(L) SD limits and the percentage error in between (P) to calculate the

standard deviations for an experimental data value (x).

Parabolic When the Parabolic option is selected, the user inputs the proportionality

constant (a) which will be used to calculate the magnitude of the standard

deviations associated with each experimental data value (x).

SD

Multiplication

Factor

When the SD Multiplication Factor option is selected, the user inputs the

multiplication factor to be multiplied by the existing standard deviations in

the system.



Exp Value

Multiplication

Factor

When the Exp Value Multiplication Factor option is selected, the user inputs

the multiplication factor to be multiplied by the existing experimental values

in the system.

Replacement

Value

When the Replacement Value option is selected, the user is asked to input the

value to replace selected SD values in the system.

Missing Value When the Missing Value option is selected the user does not enter any value.

On calculation, the selected stream and property values are assigned as

missing values.

Note that the selections associated with a particular property class persist so

that when the user changes the property class selection, the calculation option

and its associated parameters last entered by the user for that property are

displayed.

When the user clicks on the ‘Calculate’ button the program will calculate the

SDs only for the Stream and Property Class that are currently selected and in

view.

Note that even after SDs have been automatically calculated, the user is still

able to go to an individual experimental data point in the Stream Data

window and change the SD for that data point. However any changes to SD

values in the Stream Data window will not be reflected in the Automatic SD

Calculation window.

It is up to the user to decide which standard deviation calculation method

best suits the data.

Click “Close” to exit the Automatic SD Calculation window.

IMPORTANT

NOTE

All data points MUST have a standard deviation value associated with them

or else be set to ‘Missing’. This includes the TPH water and % solids, as well

as the TPH solids, overall assays and size-by-assay data.

The water balance is performed on TPH water, using the experimental %

solids and TPH solids to calculate the experimental values. The balanced

water flow rates are determined from the % solids values.

6.5.5 Preparation for Mass Balancing

Selecting

Streams and

Equipment

The Mass Balance feature of JKSimMet allows the user to select the streams and

equipment items to include in the balance, as well as selecting which

parameters can be adjusted during the mass balancing process.

Open the the Mass Balance window by either pressing the Run Balance button

on the toolbar or by selecting Run Mass Balance from the Flowsheet drop-down

menu. Once this window is open, the user enters mass balance mode where no

alterations to the flowsheet, streams or equipment can be made.

For this tutorial, mass balancing will be performed on the Learner Project, which

has already been established and has been used for examples throughout this

help file. The Learner Project file will have been supplied with your copy of the

software.

You can either follow along using this project, or alternatively if you have your

own project with data, you can use the instructions as a general guide for mass

balancing your own flowsheet. See the section Create a New Project if you61


Mass Balancing 247

are unfamiliar with the steps necessary to establish a project and you wish to

create and then load data into your own project. .

Step 1 Load the Learner Project and select the Learner Flowsheet from the

drop-down list. If necessary, resize the flowsheet window to view

the entire flowsheet. Ensure that the flowsheet is locked.

Opening the

Mass Balance

Window

Step 2 Click on the Mass Balance button on the main functions toolbar

located in the left panel just above the flowsheets list, to bring the

Mass Balance window into view.

The left-hand panel of the Mass Balance window is where you set up the

conditions for the mass balance that is to be carried out on your circuit. Here

you select which streams and equipment items are to be included in the balance

and you specify the components including the size fractions and elements

(mineral or chemical assays) that will be available for the balancing procedure.

At the bottom of this panel you have the Control fields where you select what is

to be included in the current balance and you specify values for the parameters

that control the balance.

The right-hand panel contains all of the results for your balance. When the mass

balance is under way, you can observe its progress in the top two fields which

show the number of iterations that have so far taken place plus the current

convergence value. The balance will be complete when the convergence value

goes below the convergence target that has been set in the Controls section.

6.5.6 Selecting Data

Opening the

Mass Balance

Window

As is also the case for the Simulation and Model-Fitting modules, you may

select a single unit or a cluster of units from your flowsheet on which to perform

a mass balance. This allows you to check small parts of a circuit for data

consistency.

Step 1 Open the Mass Balance window by clicking on the first of the three

large buttons located in the left panel, just above the flowsheet list.

Step 2 When you first open this window there will be a default Mass



Balance Case called MBal Case 1 in the selection drop-down at top

left. There is a Rename button that can be used to change the name of

this Test Case to something more appropriate, if required. The New

button can be used to create further Test Cases with different

balance settings, which can then be saved and returned to later.

There is also a Delete button provided so that you can eliminate any

test cases that you have previously created but no longer need.

The default selection for a new Mass Balance Case is for all of the units and

streams to be selected. Therefore the first stage in defining a Mass Balance Case

is to examine the list of equipment and streams and to decide which items are

to be included in your balance.

The next step is to remove any unwanted items by clicking on the adjacent

check-box to remove the tick. Select All and Select None buttons have also been

provided to speed up the process of balance configuration. In this case we will

be balancing with all equipment units selected and all streams - apart from the

water streams, which we will add later.

Note that if you de-select an item of equipment, the input streams for that

equipment will no longer be balanced with the output streams, even if all of

these streams remain selected on the Streams list.

If only equipment has been selected, it is not necessary to specify which streams

to include in the mass balance. The mass balancer will automatically determine

which streams should be included in the mass balance based on which

equipment has been selected.

Designation In the streams list there is a second column labelled "Designation". There are

three settings possible for the designation field, Major, Minor and Missing.

This distinction between the different categories of streams enables selected

streams to be balanced or fixed at various times throughout the mass

balancing process.

A ‘Major’ stream refers to one that can be balanced initially, for

example the plant feed, final concentrate and final tail streams,


Mass Balancing 249

and then fixed with the intermediate streams subsequently

adjusted within the circuit.

A ‘Minor’ stream is an intermediate stream that may have some

data missing, restricting it’s usefulness in the balance.

A ‘Missing’ stream is defined as a stream that is missing all data.

These streams can be omitted from the balance until such a stage

that there is enough information in the other streams to allow a

mass balance to be successful.

Note that streams belonging to the different categories are not treated

differently in the balancing process. The categories are simply groups to

which you can assign each of your streams and then later you can elect to

keep their values fixed or adjust them during the next run of the balancing

process.

There is visual feedback provided regarding the groups to which each stream

has been assigned to. When you have the Mass Balance window open, you

will notice that all the selected streams of the flowsheet are displayed in bold

black, which is the default for stream designated as Major. If you change a

stream's designation, the colour will change to bold blue for Minor or bold red

for Missing. These are just the default colours, so they can be changed to the

users preference if required. This is done via the Default Stream Properties

item on the Edit menu. These visual cues can help users identify the

equipment and streams that have been selected, which can be especially

useful when dealing with complex flowsheets.

By default, all streams are initially assigned to the Major group. As another

example of where you might make use of this facility, you may have a complex

circuit and wish to adjust values for a sub-section of the circuit only. In this

case you could assign all of the streams that make up this sub-section, to one

of the other two groups. You would then find that during the next run of the



balance, all plant values would remain fixed at their previous balanced levels

and it would be only the stream values for the required sub-section of plant

that would be adjusted as a result of this balance.

Note that the group assignation for each stream can be changed in the above

frame. To do this you just click on the required stream and then click the

appropriate button at the bottom of the list. Note that this assignation can also

be changed using the drop-down list in the top right corner of the Stream Data

window.

Step 3 In the Equipment / Streams frame, select all of the equipment items

and all streams with the exception of the two water addition

streams. Leave all the streams with the default designation of

Major.

Note that on the flowsheet there is also visual feedback for the selection of

equipment items, with those that have been selected being highlighted in bold

blue.

It is possible also to select and deselect items (both streams and equipment) for

your balance list, by clicking on these items on the flowsheet. You will see that

the bold highlighting will disappear to indicate de-selection. Clicking on them

performs a toggle action - so clicking again will re-instate the selection.

Step 4 Now examine your Mass Balance Case and ensure that:

all equipment units are selected

all streams are selected except for the water addition

streams (BM Water & Cyc Water)

all streams are designated "Major"

Because each Mass Balance Case has a name, you may set up several different

ones to examine different sections of a circuit. You can select all streams and

equipment units on your flowsheet, a single unit (together with its input and

output streams) or else a selection of units and their associated streams. Note

that they need to be contiguous i.e. with streams connecting all of the selected

units, to ensure that your selected sub-circuit does get balanced as a single

circuit.


Mass Balancing 251

In earlier versions all stream data were stored in equipment ports. To balance

a subset of the data, you needed to choose both equipment and ports

(streams). In this version, the stream data are now stored within the streams

themselves, but the same rule still applies for the balancing of data sub-sets.

6.5.7 Selecting Components

The mass balancing module can perform mass balances based on two types of

data; namely elements and size distributions. These can be used individually

or together to achieve the balance. If you also have assays of the size fractions,

then you can add an extra dimension to your balance by allowing the size by

element data to be used in the balancing process as well.

Mass balancing therefore contrasts with the model-fitting and simulation

modes in JKSimMet since in the latter modes it is only ever the size

distribution data that are used.

In the next frame of the Mass Balance window, you can select the elements

and sizes that are to be used for the current mass balance case.

In the left hand section of this frame is the list of elements that have been

entered during the project configuration stage. At the end of this list you will

see there is an element called Remainder that has been added to allow for any

mass not accounted for by the sum of the defined elements. All of the elements

will initially be selected by default. If for some reason you wish to leave out

one of these elements from the balancing process, then you can simply

uncheck the relevant check-box.

To the right of the elements selection area is a similar list for sizes, which

shows all the sizes (in mm) that have been defined for this project. Again they

will be all selected by default to begin with. In this case we will de-select all of

the sizes since we will be balancing on the assays alone.

Again, with both of these lists, there is a check-box provided at the top to

allow you to select or deselect all of them. This can be useful for speeding up

the process of defining the suite of components that are to be balanced for the

balance case in question.

Step 1 Ensure that all of the elements have been selected, but that none of

the sizes are selected.

To the right of the elements & sizes selection frame is another frame with the

heading "Adjust Streams". Here there are check boxes for the 3 categories

of streams. All three of these boxes will be checked by default. In this case we

248



want the balance to make adjustments to all streams in the circuit and in any

case, all the streams in this circuit have been left in the Major category. This

means that as long as the Major check-box is ticked, all streams will get

adjusted. However, there is no problem with leaving ticks in the other two

categories as well.

Step 2 Leave ticks in all three category check-boxes in the "Adjust

Streams" frame.

6.5.8 Solution Controls

To perform a mass balance the next step is to set the controls for this balance.

In the Control frame there are various drop-down selection fields where you

have the ability to choose the parameters that are to be involved in this

balance. In addition, you can control the way the balance begins and

concludes.

Step 1 It is wise to initially keep a balance as simple as possible, so for

the first run through of the current balance we will set the TPH

Solids to "Adjust" and likewise for Elements, but we will leave all

the other parameter fields set to "Unused".

Click in the white cells in the ‘Select?’ column to change the settings on each

parameter. There are a total of four settings that parameters may be set to,

although not each setting will be available for each parameter.

Adjust – The experimental values associated with this measurement are

included in the mass balance sum of squares calculation and a mass balance

adjusted data value is calculated by the mass balance which is consistent

with all other data in the system.

Fixed – The previously calculated balance values are held at their current

value and are used in the calculation of other parameters selected as ‘Adjust’.

This is used, for example, to keep flow rates fixed when adjusting size so as to

stabilise the convergence.

Influence – The experimental values associated with this measurement

influence the outcome of the mass balance (i.e. are included in the sum of

squares calculation) but are not returned as an adjusted consistent set of

values after mass balancing. This means the mass balanced values for this

parameter are left as zeros after balancing. The exception to this is in the case

of % Solids, where values are returned during mass balancing. The objective

of the Influence option is to allow the experimental data for the parameter

concerned to contribute to a higher level balance, even though the data for this


Mass Balancing 253

parameter are too sparse to allow the generation of its own set of mass

balanced values.

Unused – The experimental values associated with this measurement are not

included in the mass balance sum of squares calculation and its mass

balanced value is not changed.

If only certain elements or size fractions are to be sent to the balance, use the

tick boxes provided to select the required parameter. These will then be used

according to the options set in the main drop-down boxes. If an inconsistent

selection is made, an error message will be displayed when the mass balance

is run.

For balancing complex circuits, it is suggested to select all 'Major' streams in

the first instance and balance (adjust) them. Once the user is happy with this

balance, set the Major streams to 'Fixed' and adjust the minor streams, then

the missing streams.

In this way certain parts of the circuit can be balanced and fixed to continue

balancing other parts of the circuit.

The other two fields within the Control frame are "Constraint" and

"Convergence". The first of these relates to how missing values are to be

handled by the balancing engine. There are two options for this field;

"Experimental" and "Balanced".

If you select "Experimental" here, any stream values that are missing will be

ignored in carrying out this balance. If you select "Balanced", then wherever a

missing experimental value is encountered, the balancing engine will

temporarily substitute the balanced value obtained from the last time the

balance was run.

Step 2 For the first run of this balance we will set the Constraint to

"Experimental".

The "Convergence" field is where you determine how close the agreement

between stream values has to be before the balancing engine decides that a

balance has been achieved. When you click on the "Convergence" drop-down,

the alternatives you will be presented with are "Average", "Good" & "Tight".

The values for the convergence criterion that are associated with these

alternatives are 0.1, 0.01 and 0.001 respectively. Once you have made your

selection, it will be the appropriate number rather than the associated word,

that will appear in the Convergence field.



Step 3 For this balance we will set the convergence to "Good", so the

number appearing should be 0.01.

Typically you would use either % solids or TPH water as a component when

balancing a flowsheet that involves gravity separations. Note that if you use

% solids as a component, then you must specify appropriate water additions.

For a description of what happens when % solids is included as a component,

see the next topic on Water .

It is usually a good idea to run mass balancing in stages however. In this case

we will just run the balance using the TPH solids and the elemental assays as

we have good measurements of these on all streams except the cyclone feed

stream. After we have completed this simplified balance, we will then add in

the water as an additional parameter to be balanced. After this, size

distributions can be added in as well.

Some Comments

on Mass

Balancing

Note that it is not necessary to understand the detailed workings of the mass

balance engine in order to make use the mass balance module. The following

comments about its workings may be useful however.

The mass balancing algorithm runs in several stages.

The first is the simple solution, which is analogous to multiple linear

regression. Unless the data have serious problems the balance will converge

in one step; that is, the second solution will be the same as the first.

If small negative values occur, you can increase the number of steps to

eliminate such values. However, recheck your data carefully. Negative values

indicate measurement bias.

For higher numerical accuracy you may increase the iteration limits. However,

there will be no gain in the balance accuracy because data accuracy will be

the usual limit.

Hint: Read the section on problems relating to mass balancing before

adjusting these settings.

The values shown above are the default values.

If the adjusted data show unacceptable inconsistencies, then you must either

reduce the limit or re-scale the assays. As an example, if you have Au assays

expressed as a fraction (giving a number such as 1.0 E-06) this would not

work too well with a convergence criterion of 1.0 E-05. In this case it would be

most sensible to re-scale the assay, which might involve expressing your gold

assays as Au ppm. You would of course then also need to specify that the

assay total is not constrained to 100%.

6.5.9 Water in Balancing

If you have selected TPH Water as a component from within the Control frame,

then you will be also mass balancing any water additions to the circuit

together with the water contained in all the slurry flows throughout the

circuit.

Note that you cannot use % Solids unless you first select TPH Water as a

parameter to be adjusted. Except for the water addition streams, experimental

values for water are entered by specifying the % solids values for the streams.

However, the program calculates TPH Water values from these values and it is

254

267


Mass Balancing 255

TPH Water that is used by the engine as a balancing component. The % solids

is not adjusted per se, but it can be used in determining the error after each

iteration and this is what is meant by "influence".

To allow the mass balancing engine to include water in the balance, you need

to ensure that you have selected any water feeder product streams using the

streams select list, in the Equipment / Streams frame. In the Learner Project,

there are two water feeders on the Learner Flowsheet.

Measured data and estimated SD's are entered in the data window associated

with the water streams emanating from these water feeders.

6.5.10 Running the Mass Balance

Starting the

Balance

This is the simplest step. Once the components have been specified, the

desired equipment and streams selected and the balance controls set, the mass

balancing can begin.

Click on the Start button which is located at the bottom right of the Mass

Balance window.



The mass balancing program will run and when the balance has completed,

the results will be summarised in the right hand panel of the Mass Balance

window.

In the Results frame at the top of this panel is the actual convergence value.

This is the value that is compared with the required Convergence value

selected by the user in the bottom drop-down of the left-hand panel. The

program considers the balance is complete once the actual value goes below

this user specified convergence setting.

The right-hand field of the Results frame is the number of iterations that the

balance has gone through before arriving at the indicated convergence value.

The frame below the Results frame is labelled "RMS Errors" - standing for root

mean square errors. In this frame you can gauge how well the data has

balanced compared to the previous balance. Smaller values of the RMS errors


Mass Balancing 257

will indicate that a better balance has been achieved.

The RMS errors listed here are divided into the various areas of balancing, in

line with the areas that can be selected from within the Controls frame:

The Totals refers to the solids mass flows alone - it does not include

water.

Flows refers to the volume flows in the various streams, consisting of

the volumes of both the water and solids in all streams, including

slurry streams and water feeder flows. Note that balancing on the

volume flows only occurs when TPH water has been selected as one

parameters to be adjusted.

Assays will have an RMS error displayed if you have selected

"Adjust" in the Elements drop-down from the Control frame.

Sizes will have an RMS error when Sizes has been selected for

adjustment from the Control frame.

Likewise Assay by Size will have an RMS error value if Size by

Element has been selected for adjustment.

Below the listing of the RMS error values is the Parity Graph which allows an

easy visual assessment of how good the balance has been. This graph is

plotting the experimental values against the balanced values, so for a perfect

balance, with no adjustments needed, all the points would be sitting on the 45

degree line. The distance that points are away from the 45 degree or parity line

is a measure of how much adjustment was needed for these parameters to

achieve the balance.

Generalised

Strategy for Mass

Balancing

If you have assays on most or all streams, the normal sequence for mass

balancing would be to initially set TPH Solids and Elements to "Adjust" with

all other parameters set to "Unused". Once a balance has been achieved using

these parameters, you would next set both of them to "Fixed" and now set the

TPH Water to "Adjust" and the % Solids to "Influence". Then after this balance

has run, the next step would be (if you have sizing data), to set both water

parameters to "Fixed" and set Sizes to "Adjust". Finally, if you also have Size

by Element data you would set Sizes to "Fixed" and the Size by Element

parameter to "Adjust".

If you are working with Sizing data only and do not have any assays, you

would start the process with TPH Solids and Sizes set to "Adjust". After this

balance runs, you would set these two parameters to "Fixed" and set the TPH

Water to "Adjust" and the % Solids to "Influence".

The next step in the Learner Project is to make the TPH Solids and the

Elements fixed and to balance on water, making the TPH Water set to "Adjust"

and the % Solids set to "Influence. After you change these balancing settings,

you should click on the Clear button prior to re-running the balance. The

Mass Balance window will then look like the one below.



Pressing the Start button will then produce a balance similar to the one shown

below.

Since in this case we also have sizing data, the next step is to balance on these

data. To set this up you need to click in the check-box labelled "Select/

Deselect All" above the Sizes list in the Elements / Sizes frame. This will select

all of the sizes that are present in the size analysis for the samples in this

circuit. You then need to uncheck the 13.2 mm size, since this contains a value

of zero for the experimental retained mass for all three products and this will

cause problems for the balancing routine.

In order to run the balance on the sizing data, you need to also switch the

TPH Water and % Solids back to "Unused". When the balance runs, you

should see the window looking similar to the screen grab below.


Mass Balancing 259

In this case we do not have any size by assay data, so at this point the

balancing process is complete. If you did have size by assay data, the next

step would be to set the Sizes back to "Fixed" and then the Size by Element to

"Adjust".

The next step is to look critically at the balance results and there are various

ways of doing this. The next topic discusses the options here and what you

need to look for in examining the balance results.

6.5.11 The Mass Balance Engine

The Mass Balance Results section reports the value at which convergence

occurred as well as the number of iterations that were required to reach that

value.

In most cases of mass balancing, there will be numerous missing data. The

ideal scenario of the mass-balance algorithm is that the user may specify all

their data, press a button and have the calculated values returned in seconds.

Unfortunately the number of missing data points generally prevents the

algorithm from being quite that accommodating. Therefore, mass-balancing

needs to occur using a hierarchical approach; that is by first mass-balancing

flows, then sizes and total assays, then assays within size-classes. This

hierarchical approach was discussed previously . The key interface is

therefore the Control frame in the Mass Balance window you specify which

levels are to be mass-balanced.

The mass balancing algorithm in JKSimMet allows high level variables to be

calculated using lower level results without actually estimating the low-level

values. For example, it is possible to use size information to estimate flows

without actually having to estimate the calculated values of size. Data-

checking is performed only for those variables that are being mass-balanced

(not the values of lower level values used to influence the mass-balance).

However one needs to bear in mind that unrealistic low-level standard

deviations will cause unreasonable weighting to the lower levels

Data Checking Data-checking is required to ensure that values are realistic. The data-

235



checking occurs for all levels of variables to be calculated, and assumes that

higher level values have reasonably small standard deviations of the

calculated values. In other words data-checking treats upper level values as if

they are fixed.

Data-checking is used to check the reliability of the data. In particular, if

standard deviation values are too small, the algorithm will have difficulty

converging.

The data-checking algorithm works by considering the difference between

flow (of any property) going into and out of a unit. The difference should be

consistent with the standard deviations. For example, for a unit having one

stream in and two streams out, the total flow values may be represented by f1,

f2 and f3 with corresponding variance values v1, v2 and v3. The flow

difference is:

The expected variance of this difference value is given by:

Thus the statistic:

provides an estimate of the reliability of these data. The expected value of r is

1. This r value is referred to as the RMS (root mean square) value.

An RMS value greater than 3 usually indicates that the data contains an

outlier or that the standard deviations are too small.

Using the RMS

Errors

The Error Analysis section of the Control/Run window gives an indication of

the quality of the mass balanced data through the use of RMS (root mean

square) errors.

As its name suggests, the root mean square error is the square root of the

residual mean square error, which is the error associated with fitting the mass

balanced data to the experimental data.

A root mean square error of unity means that all data points were estimated

with errors similar to the measured standard deviations of the experimental

data points.

Therefore, when performing a mass balance, an RMS Total value of

somewhere between 0.5 and 2.0 indicates that the experimental data is good

and that the correct standard deviations have been used.

Along with the RMS Total value it is possible to check the error values (i.e.

(observed – predicted)/sd) on the other parameters used in the mass balance.

Click the ‘Detail’ button next to each parameter to see information about that

parameter.


Mass Balancing 261

This window, for instance, would indicate that particular problems exist with

the Cyc U/F and BM Product streams.

Identifying particularly problematic streams allows the user to immediately

focus on which data values may be less accurate than indicated by their

standard deviation. It may be necessary to change standard deviation values

to improve the mass balance.

6.5.12 Checking the Balance

There are various ways in which the user can assess the results:

The Overview window is probably the most useful way to check data and

results. It also allows recovery of any component to be displayed for all streams.

See the Using the Configurable Stream Overview topic for details of the

Overview facility.

In the RMS Errors frame of the Mass Balance window, the magnitude of the

accumulated error values under the various parameter categories, are all

indicators of how close the original experimental data were to being already

balanced. Smaller values of the RMS Errors indicate less adjustment was

required to produce the balance. Moreover, in the case of these fields,

comparisons between successive mass balances can be made. If these values are

smaller than they were in the previous run, then the balance is getting better. If

they are getting larger, then the adjustments you have made are taking this

balance in the wrong direction.

You can also judge the relative success of mass balancing by looking at the

individual stream data windows. Examine the values in the Error column.

Again, smaller error values indicate less adjustment has been required.

The parity graph on the Mass Balance window allows for a good visual

assessment of the balance. The further the data points are away from the 45

degree line, the greater was the adjustment needed to balance the parameters in

question. The TPH Solids data usually consist of numbers that are very large

compared to the assay data and when the two are plotted together on this

graph, the assay data will lie in a clump near the origin, which is not very

useful for assessment. To overcome this problem, you can temporarily switch

36



the TPH Solids to "Unused", while leaving Elements on "Adjust". You will also

have to de-select "Remainder" from the elements list, since this will be a

relatively large number also, possibly approaching 100. After you have done

this, you should get a much better picture of how well the elemental data have

balanced. It should be noted though that you cannot actually carry out a

balance with the TPH Solids set to "Unused". Note too that you can hover the

mouse over individual data points to identify them, as is illustrated in the

screen grab below. Don't be too impatient here though - you do need to have the

mouse positioned over the point you wish to identify for between 1 and 2

seconds before the data will appear.

The Configurable Graphing facility allows the user to plot experimental and

balanced size distribution data on the same screen. Further description of this

can be found in the section Plotting Size Data Graphs .

If mass balancing a large and complex circuit is proving difficult, a useful

technique for tracing the source of the problem is to dissect the circuit into

smaller chunks for balancing. The Mass Balancing module allows balances to

be carried out on a single unit or on a small set of units, isolated from the main

circuit by means of the Select List facility. This allows you to put the test data

under a microscope.

If circuit conditions were changing as you did your test work, you may find that the

unstable sections of the plant will have yielded unusable results. As a general

principal, a good balance depends on having steady state conditions and varying

conditions will usually produce nonsense.

6.6 Presentation of Mass Balance Results

There are two main ways to present the results of mass balancing:

viewing on screen via the Configurable Stream Overview window

and

printing or exporting via the Reports function.

We shall deal with these in turn. For mass balanced data, graph plotting is

limited to GSIM format.

265

Version 6.0.1 - March 2014 Presentation of Mass Balance Results

Mass Balancing 263

6.6.1 Configurable Stream Overview

Using

Configurable

Stream

Overview to

View Balance

Results

The Configurable Stream Overview window gives you a powerful means of

summarising your data and checking it for adjustment problems. There are some

built-in overviews that will already be present when you first open the

Configurable Stream Overview. This includes one that contains Experimental,

Balanced and SD data. This one is all you would normally need for assessing

the results of a mass balancing procedure. However, as implied by the name,

this overview window can be configured by the user and you can create your

own overviews with additional data displayed or with just a subset of the

streams in your flowsheet displayed.

The best way to use the overview feature is to compare experimental and

balanced values for each assay (or size fraction) across the complete circuit. This

will give a very useful picture of the accuracy of the data and the mass balance.

Step 1 Left-click on the Configurable Stream Overview button ( ) on the

main JKSimMet toolbar. This brings the Configurable Stream

Overview window into view.

Step 2 Select From the Select List at top left, select the pre-configured

overview the existing Overview that is labelled "Stream Data (Exp,

Bal & SD)".

Note that from within this window, you can elect to change the way you view

the sizing data. The drop-down at top right contains the sizing data options of

% Retained, Cum % Retained and Cum % Passing. You can also gain access to

the SD Calculation window from here via the button next to this drop-down.

This is provided here since after examining the most recent balance data, it will

often be the case that you may need to modify certain SD values before re-

running the balance.

6.6.2 Reports Function and Printing

Printing Mass

Balance

Results

Normally for reporting the results of a mass balancing procedure you would most

likely want to show the experimental, balanced and SD values for each type of

data involved and for each of the streams included in the balance.

Printing

Individual

Port Data

Windows

One way to do this is via the individual stream data windows. To open a stream

data window, just double-click on the required stream in your flowsheet. These

windows all have SD and Mbal data as pre-configured display columns. You

cannot directly print these windows, but you can copy the grid from them into

Excel. To do this you press the Copy button, located top centre of the Stream Data

window. As it is only the active tab that gets copied, you need to ensure that you

36

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Version 6.0.1 - March 2014Presentation of Mass Balance Results


have the appropriate tab selected for the type of data that you are intending to

report on.

This method may occasionally be useful if you are wishing to report the data for a

particular stream, but in general one of the other two methods below is probably

more practical.

Printing the

Configurable

Stream

Overview

Another alternative is that once you have the Configurable Stream Overview set

up according to your requirements, you can either print it directly or else export it

to Excel for further manipulation before printing.

When you use the Print function directly, the options for manipulating the format

of your report are somewhat limited and it is likely to span across several pages.

In most cases it is probably better to use the Export function and then print a

report from Excel.

There are two Export buttons - one is for exporting just the overview that is

currently displayed, while the other will export all of the overviews that have

been set up for this project. Note that this includes all the system configured

overviews as well as any that you may have created. The export function will

create a new Excel sheet for each of the existing overviews.

The copy grid option is also available from the Configurable Stream Overview

window and this may sometimes be useful as a quick way of getting the required

data into Excel for further manipulation.

Configure

and Print a

Report

Probably the greatest flexibility for report production is afforded by JKSimMet's

integrated Report generator. When you press the Report button ( ), a window

similar to the illustration below will open.

From here you can create reports with complete flexibility regarding which

equipment items, streams and types of data that are to be included. There is also a

drop-down to allow you to choose the way your sizing data will be expressed in

the report.

Version 6.0.1 - March 2014 Presentation of Mass Balance Results

Mass Balancing 265

For a mass balancing report, it is recommended that you place a tick in the

Summary check-box. When you do this, the formatting of the report will be

modified for easier comparison of values between streams. With the Summary

check-box ticked, the stream data will be arranged with the stream headings

across the page and the parameters down the page, grouped by data type. If you

have also selected equipment for the report, the equipment data will still be listed

down the page along the left-hand border, but it will have a lot less detail than in

the non-summary version.

6.6.3 Plotting Size Data Graphs

Plotting

Graphs of the

Mass

Balancing

Results

On the mass balancing window there is a graph of experimental data versus

balanced data, which provides a visual assessment of how much of an

adjustment of the various data points was needed to achieve the balance.

For the sizing data it is possible to get a more detailed visual feedback on how

much adjustment was needed, by plotting a size distribution graph of both the

experimental and balanced data. A drop-down is provided to allow you to

select the format of the sizing data. This can be either cumulative % passing, %

retained or cumulative % retained. The data can be plotted for a number of

streams on the same chart, to allow comparisons.

An example of the graphing facility with the required data types in the process

of being selected from the drop-down, is shown in the screen grab below.

Once the streams to be displayed have been selected and the data format and

data types selected, you simply click on the Graph tab and the required chart

will appear in place of the graph configuration table. The screen grab below

shows a typical example in which the user has chosen to show the circuit feed

from the Learner Flowsheet plus the two products from the cyclone.

Version 6.0.1 - March 2014Presentation of Mass Balance Results


It is also possible to make changes to the way this graph appears, using the

Format button near the top right of this window. If you click on this button, a

new window will open where you can make a number of changes to the chart

formatting. An example is shown below.

Any graph that you generate here can be easily inserted into an Excel or MS

Word report using the Copy button at top right.

Version 6.0.1 - March 2014 Problems Related to Mass Balancing and Possible Solutions

Mass Balancing 267

6.7 Problems Related to Mass Balancing and Possible Solutions

There are, of course, many problems that may be encountered during mass

balancing. It is possible however, to point out some of the more common

problems and a description of these has been set out in the remainder of this

section. While the list below is not comprehensive, we hope that it will alert

you to some of the more significant pitfalls.

Errors, Warnings,

Faults

Some problems detected by JKSimMet can produce error messages. In version

5 the errors had error numbers and were referenced via a key that could be

found in the help file. In version 6 it is no longer necessary to refer to a key

since the error explanations now appear in the error message window.

Graphical

Analysis

The graphing capability of JKSimMet is the most powerful way to examine

your data fit. Discontinuities in size data highlight poor data or a change in

size measurement technique. Graphical analysis also highlights any bias in

the data fit.

Different Sizing

Techniques

Be very wary of changes in size measurement technique e.g. from screens to a

Cyclosizer.

Different Assay

Techniques

Where assay techniques change between stream samples, as they sometimes

do for different assay ranges, there may be inherent biases within the assay

techniques. These will lead to biases within the mass balance.

Skill versus

Practice

Mass Balancing is not a cut and dried procedure. The only way to acquire a

useful skill level is to practise on a wide range of real data. JKSimMet offers a

user-friendly environment for what are really very complex and powerful

mathematical techniques.

Data Note that it is necessary to have enough feed and product data to achieve a

useful mass balance. This is very important. Generally you need to have

redundant data and the more of this you have, the better. If you have no

redundant data at all, then the mass balancing exercise reduces to just a

calculation – i.e. there is only one solution to the balance. In this case the

internal checking that comes from having these extra data (and is also one of

the major advantages of mass balancing), will no longer be operating.

Without redundant data, there could well be a very large error in one of your

data points and you would have no way of ever being alerted to it.

Common Mass

Balancing

Pitfalls

There are a couple of simple traps which can appear in many guises. If you

become aware of these now you may recognise them more easily when you

encounter them in the future. These are discussed in the two sub-topics that

follow.

6.7.1 The Middlings Problem

The Middlings

Problem

Below we have a single unit flow diagram for a separation node where there

is a middlings stream of assay m.

In this situation there are not enough assays to go around.

However, if we have two assays in each stream, we would write them out as

Version 6.0.1 - March 2014Problems Related to Mass Balancing and Possible Solutions


simple equations and solve for two unknowns. However, if m really is a

middlings stream, it will be close to a in composition and very often recycled

back to it.

In this case, no matter how accurately we can sample and assay the streams,

we can only find out:

the ratio between flows b & c (if m goes elsewhere)

or

the flows in b and c if m is recycled.

The actual flow rate in m can be anywhere between zero and infinity.

However, there is a straightforward solution. Measure (or estimate) the flow

rate in stream m and input this flow rate as data.

The mass balancing module allows you to do this.

6.7.2 The Infinite Division Problem

The Infinite

Division

Problem

If one wishes to extract maximum information from a survey, it is not unusual

to assay on a two (or even three) dimensional matrix, for example, assay by

size or assay by size by specific gravity. This subdivides the stream into even

smaller sub-groups. Each sub-group has an extra step of processing and an

increased relative error. Hence, we tend towards trying to solve for (0 - 0) / (0 -

0). This is not a useful numerical exercise.

The solution to this problem is straightforward, however.

You should first use the total assays where there are large differences, to

calculate the mass balance flow rate solutions. Once you have these flow

rates, fix them by selecting "Fixed" from the TPH Solids drop-down (in the

balance controls frame) and only then add in all of the smaller fraction assays

to the mass balancing problem.

Once the flow rates have been defined, the mass balancing module will be

more easily able to allocate the minimum adjustments required to make all of

the fractional assays consistent.

6.8 Metallurgical Accounting

Use in

Metallurgical

Accounting

The day to day data collected from a mineral processing plant are rarely

consistent and will almost always contain redundant information. In general,

any two methods of calculation will yield different results. The challenge for

metallurgical accounting is to produce adjusted data that are both self-

consistent and as accurate a representation of plant performance as possible.

Consider a typical base metal concentrator with several products from several

circuits,

At each point marked , we have Au, Cu, Fe, Pb and Zn Assays. For the feed,

Version 6.0.1 - March 2014 Metallurgical Accounting

Mass Balancing 269

we have weightometer readings and for the concentrates we have load out

weights with stockpile surveys.

If we select an accounting period that is large compared with the circuit

residence time, we can carry out a mass balance over this complete data set. If

large adjustments are required, these may be an indication of problems in

either sampling or assay techniques. In this case you may need to select

smaller circuits for mass balancing in order to isolate and identify these

problems.

Once a consistent set of adjusted data is produced for each accounting period,

the sums of these sets will also be consistent.

If assays and flow rates are available on a short time scale, e.g. several times

per shift, these data can be balanced for each time period, printed to a file or

exported to most Windows spreadsheet or word processing packages using

copy and paste.

JKMetAccount For users with a serious interest in metallurgical accounting, the

JKMetAccount program was created to enable the Metallurgist or Plant

Manager to track the performance of a mineral processing plant over

time.Changes to a plant flowsheet, which can so often cause problems for a

spreadsheet based system, are easily accommodated by the JKMetAccount

software.

The major strength of this program comes from harnessing the power of the

JKMBal mass balance engine (and more recently a model based mass balance

engine), within a rigorous data management environment that is accessed via

a user friendly graphical interface. JKMetaccount also still provides for very

flexible reporting, as it utilises the formatting power of Excel within its report

production module.

With its rigorous data management advantage over a spreadsheet system, we

believe that JKMetAccount will in time become regarded as an indispensable

tool for modern mineral processing plants.

At the end of 2006, all rights to the JKMetAccount program were sold to the

large Brisbane based software development company Mincom, whom were

considered better able to handle the further development and marketing of

this product. Mincom have since been taken over (in July 2011) by ABB and

are now part of the ABB owned company Ventyx.

If you are interested in finding out more about JKMetAccount, further

information can be obtained either from the JKTech website (http://

www.jktech.com.au/commercialisation-case-studies) or directly from Ventyx,

whose contact details can be obtained from their website at http://www.ventyx.com/.

6.9 References

LYNCH, A.J., 1977. Mineral Crushing and Grinding Circuits, (Elsevier,

Amsterdam), Chapter 7.

LYMAN, G.J., 1986. Application of Gy's sampling theory to coal, International

Journal of Mineral Processing, Vol 17:1-22.

GY, P.M., 1982. Sampling of particulate materials: theory and practice, 2nd Ed,

http://www.jktech.com.au/commercialisation-case-studies

http://www.jktech.com.au/commercialisation-case-studies

Version 6.0.1 - March 2014References


(Elsevier, Amsterdam), p 431.

MORRISON, R.D., 1976. A two stage least squares technique for the general

material balance problem, JKMRC Internal Report No 61

(unpublished)

Part

VII



7 Model Fitting

Model Fitting This section provides information about the model fitting capabilities of

JKSimMet V6.

7.1 Introduction to Model Fitting

Purpose This chapter describes how to use the JKSimMet model-fitting mode. Model

fitting allows JKSimMet to be fine-tuned to each specific plant and operating

condition, or even to particular ore types. It does so by adjusting selected

model parameters on the basis of systematic differences between measured

product data and simulation predicted product data.

The model fitting procedure can take into account any measured flow rates

and estimates of their accuracies.

Previously the determination of the model parameters was performed in

spreadsheet-based programs, involving complex formulae. This has been

very time consuming and potentially prone to error. As more companies are

becoming skilled in developing models, JKSimMet enables the fitting routines

to be standardised. The ability to use JKSimMet to fit the model parameters

greatly increases the efficiency and level of confidence in developing the

models; although a high degree of training is still required to ensure

reasonable results are obtained.

Overview For both plant designer and plant operator, model fitting is primarily

concerned with the collection of accurate experimental data, at either pilot or

full plant scale. The model fitting process provides a powerful means of data

examination or assessment as well as the compression of thousands of data

points into a few parameters.

The parameters characterise how a particular ore behaves in a particular

plant. This characterisation can be used to find the optimum plant settings

with respect to various criteria, or even to find an optimal plant configuration

to achieve stated objectives.

As with all data analysis or prediction processes, however, the quality of the

output is strongly dependent on the quality of the input. The computer jargon

for this phenomenon is GIGO or GARBAGE IN – GARBAGE OUT. A serious

difficulty with all realistic simulation systems like JKSimMet is that they will

produce very plausible looking nonsense from rubbishy data.

Hence, just as the spreadsheet is not a replacement for the accountant,

JKSimMet is not a replacement for a metallurgist or process engineer. There is

no substitute for professional expertise or experience, especially in the

collection and analysis of large quantities of data. JKSimMet provides such a

professional with a tool of enormous power.

The general procedure for model fitting is:

Collect data;

Analyse data;

Optimise plant using models;

Adjust plant;

Version 6.0.1 - March 2014 Introduction to Model Fitting

Model Fitting 273

Collect data to confirm

And start the cycle again.

7.2 Background to Model Fitting

Default

Parameters

The JKSimMet models are provided with a set of default parameters and, in

most cases, a range of parameter values.

For any real mineral processing operation, the best-fit parameters will almost

certainly be different from the default values provided with the system.

There are several classes of parameters used as model inputs:

Machine

Parameters

Firstly there are the machine dependent parameters. These are typically

dimensions and key operating adjustments.

Ore Parameters Then there are the ore dependent parameters. For example, the work index or

specific gravity or appearance function for a particular ore at a particular

energy.

Operating

Parameters

There are also the calculated or measured operating parameters. These

usually depend on a combination of machine and ore dependent parameters

and ore feed rates, etc. Examples are cyclone feed pressure and crusher power

draw.

Circuit Flow

Rates of Solids

and Water

Process instrumentation often provides an estimate of solids and liquid flow

rates in the circuit. An example might be the solids mass flow rate to a cyclone

classifier. In some cases, such a flow can be treated as data. If it is

unmeasured, it may be varied until a best fit to the other data is achieved. In

this case, the flow rate effectively becomes a parameter.

Model

Parameters that

can be Fitted.

Each model has a list of parameters that can be fitted. Each parameter to be

fitted is selected from a menu for that model. These menus are listed for each

of the models within the Model Descriptions section.

7.3 How the Model Fitting Program Works

The model-fitting program works by calculating the differences between the

predicted and experimental data, and then deriving from these differences a

weighted sum of squares value (WSSQ). On its first iteration (step), the

program makes a small adjustment to each parameter in turn, with each

adjustment followed by an internal simulation to determine its affect on the

weighted sum of squares value. This step is used to estimate the magnitude

and direction of the adjustments to the parameters required to minimise the

WSSQ. On subsequent iterations, the program varies all the fitted parameters

simultaneously, noting the effect of the adjustments. This process is repeated

until the program is stopped for one of the following reasons:

A minimum WSSQ has been reached;

The maximum number of steps set by the user has been reached;

The adjustments made to the parameters are having no significant

effect on the weighted sum of squares value;

Operator intervention.

Whereas simulation uses given feed data and given model parameters to

294

Version 6.0.1 - March 2014How the Model Fitting Program Works


predict the product data, the model-fitting program uses the sum of the

squares of the differences between the predicted and the actual product data

to adjust the model parameters.

The difference between simulation and model fitting is represented

schematically below:

Schematic to Illustrate Difference between Simulation and Model

Fitting

7.4 Model Fitting as Applied in JKSimMet

Model fitting allows the simulation models present in JKSimMet to be tuned to

specific real world operating conditions. To do this, the user collects

experimental (stream) data and periodically engages in model fitting to

update parameters.

Version 6.0.1 - March 2014 Model Fitting as Applied in JKSimMet

Model Fitting 275

Model fitting consists of adjusting the model parameters so that the model

predictions line up as closely as possible with collected experimental data.

These data are collected from the real plant or circuit, and they are mostly data

associated with the circuit product stream or streams.

Any parameter within the comminution models can be incorporated into the

fitting routine. In general, the model parameters are within the comminution

machines themselves, while the data to be fitted against are within the

streams.

7.5 Preliminary Data Setup

The initial steps in performing the model fitting data analysis are similar to

those required for all previous functions.

7.5.1 Creating the Flowsheet

To create a new project, follow the procedure discussed earlier under the

topic Creating a New Project . This will load a new project with a blank

flowsheet called FlowSheet1.

Lock the flowsheet once the flowsheet has been drawn, including labels given

to equipment and streams.

7.5.2 System Properties

The first step in model fitting for a given flowsheet is to check the system

properties defined for that flowsheet. First make sure that you have selected

the flowsheet you wish to deal with. Remember that you need to double-click

on a flowsheet from the list in order to select it. Next you should click on the

System Properties icon or select System Properties from the Flowsheet sub-

menu to open the System Properties window.

System

Properties

In JKSimMet there are only two classes of system properties:

Elements

Miscellaneous

In JKSimMet there are no predictive models that deal with the dispersion of

elemental flows around flowsheet nodes. Any elements that you enter as part

of the system properties will only be used within the mass balancing

function.

For the miscellaneous category, there are two built-in properties solids SG and

water SG. Both of these will have relevance for a number of the predictive

models. Generally the water SG will not vary greatly, but solids SG will have

more variation and changes here could have a substantial effect on the output

from models where gravity effects are important, such as the cyclone model.

Other aspects of the System Properties window are discussed in the

chapter on Editing the Flowsheet Data.

7.5.3 Stream Specification

Click on the Stream icon or select Stream from the Flowsheet menu to open

178

192

Version 6.0.1 - March 2014Preliminary Data Setup


the Stream window. From here you can select individual streams. See

Entering the Data under the chapter Learning Mass Balancing for more

detailed information.

For model fitting within JKSimMet, the user must ensure that sizing data has

been entered as part of the stream data for all streams associated with the

equipment item or items concerned.

For the models associated with these equipment items, the default values for

the parameters being fitted can be used as starting values.

7.5.4 Data Input

Feeder Units JKSimMet requires the user to enter data into the Feeder units, even though

this data has been previously used in the streams for the mass balance.

Ensure the following data has been entered for the feed stream(s):

TPH solids

% solids

Size distribution

Configurable

Equipment

Manager

In a similar manner to setting up the flowsheet for simulation, the user must

enter starting point parameter values for the equipment units. The addition of

these data can be achieved via the Configurable Equipment Manager or be

entering the data directly into the individual unit windows.

The Configurable Equipment Manager can be particularly useful where you

have multiple equipment units with the same associated process model.

Survey Data If you have survey data that has been entered into the survey data screen, the

task of getting your data into the various flowsheet streams can be efficiently

accomplished via the Transfer button on this Survey Data window.

7.5.5 Mass Balance Prior to Fitting

It is generally recommended to balance experimental data prior to moving into

the model fitting routine. See the section on Mass Balancing for more

details

Ensure the following steps have been performed:

Experimental Data Specification – check to see that you have size fraction data

entered for all streams involved with model fitting.

Enter data in either the Configurable Stream Overview or the individual

stream windows.

Calculate ALL standard deviations, either by using the Automatic SD

Calculator or by manually entering values. The Automatic SD Calculator is

accessed from either the Configurable Stream Overview or from individual

stream windows.

Ensure standard deviations are present in the system for:

TPH Solids

TPH Water

237

153

175

230

Version 6.0.1 - March 2014 Preliminary Data Setup

Model Fitting 277

% solids

ALL size fractions

Where no experimental data is present, ensure the standard deviation value is

set to ‘Missing’.

Run the mass balance using the hierarchical structure as discussed in the

Mass Balancing section:

Adjust TPH solids and elements first until reasonable values have

been obtained, keep these as fixed for subsequent runs;

Adjust TPH water, using % solids as influence, then leave as unused

for subsequent runs;

Adjust size fractions (wt %)

Review results using the parity graph, Configurable Stream Overview and

individual stream windows to ensure realistic values.

7.5.6 The Model Fitting Window

Opening the

Model Fitting

Window

Step 1 Open the Model Fitting window.

The Model Fitting window within JKSimMet contains several frames. When

first opened, either by clicking on the Model Fitting button ( ), or by selecting

Run Model Fitting from the Flowsheet menu, a window similar to the one

shown below will appear.

At the top left is a drop-down selection box for selecting the Model Fit Case. By

default, there is a system generated model fit case called Whole Circuit, which

as the name implies, encompasses all the equipment items in your flowsheet

that have associated models, plus their connecting streams.

The Whole Circuit model fit case cannot be deleted. However, you can add

(and/or delete) as many more model fit cases as you wish, so as to enable the

fitting of either individual equipment items or sections of the plant that

encompass any number of connected items.

230



Creating a New

Model Fit Case

Step 2 Add a new model fit case for the ball mill only.

To add a new model fit case, you first click on the button at the end of the drop-

down (circled in the screen grab below).

After clicking on this button, a window labelled Simulate will open containing

a similar drop-down list at the top, this time labelled Simulation Select List.

From this window you can add new model fit cases as well as make any

changes needed to ones you have previously added.

A screen grab of this window is shown below.

Beneath the drop-down list there are two panels, the left-hand one showing a

list of equipment items and the right-hand one showing a list of the streams.

You will notice that when Whole Circuit is selected from the drop-down list, all

the equipment items and streams will be selected by default and you will not be

able to deselect any of them. To create a new select list (model fit case), click on

the New button (circled above) and then enter a name for the new list in the

dialog box that will then have opened (see below).

Setting up the

New Model Fit

Case

In this case we will elect to fit the ball mill in isolation as our starting point for

model fitting the items on this flowsheet, so you could enter something like 'Ball

Mill Only' for the name. As a general principal, it is usually best to model fit the

equipment items individually before attempting to carry out model fitting on the

entire circuit. That said, in the case of a closed circuit ball mill configuration, it

is often better to fit the ball mill concurrently with the associated cyclone (see

ball mill model description ). However, since our purpose in this example is

to demonstrate the more normal sequence, we will fit the ball mill first, followed

by the cyclone and finally the whole circuit.

361


Model Fitting 279

After pressing OK to name the new model fit case, you will be back on the

Simulate window where you can specify the equipment and streams that are to

be included. Here you will find that in addition to the Whole Circuit model fit

case, Ball Mill Only is now an additional option for selection from the drop-

down list. If you now select this item, you will see that initially there are no

equipment items or streams selected.

To set up the new model fit case, you should now select Ball Mill from the left-

hand panel. After doing this you will find that all of the input and output

streams for the ball mill will be automatically checked in the right-hand stream

selection panel. You can modify this selection if required. However, bear in

mind that the only streams you will have available in the Model Fitting window

when this model fit case is selected, will be the ones have been checked in the

Simulate window.

After setting up the model fit case, you should return to the Model Fitting

window. You do this simply by closing the Simulate window - via the corner

close button ( ). If Ball Mill Only was selected when you closed the

Simulate window, then this will also be selected on returning to the Model

Fitting window.

The model fitting window should now look similar to the screen grab below:



Selecting

Equipment

Items with

Associated

Models and

Showing their

Parameters

We will use the Ball Mill Only case for initial model fitting. However, to

illustrate a point we will now select Whole Circuit again. You will notice that

the parameters appearing in the centre panel list will be appropriate for

whatever equipment item you have clicked on in the equipment selection list at

left. Note that when you click on a grey Equipment cell (or on a Model cell) you

will bring up the list of the appropriate parameters for the selected item of

equipment - you don't have to put a tick in the check-box next to the equipment

item for it to be selected and to see the associated parameters. The check-box is

there simply to provide a means of quickly selecting the appropriate streams in

the Stream Error Selection list. When you place a tick in one of the equipment

item check-boxes, the appropriate streams will also be ticked. The streams that

get selected for error assessment by default will be the product streams from the

selected item of equipment.

You are not bound by this stream selection, but it does represent what would be

the normal choice of streams for use in assessing the veracity of the parameter

values, after each round of simulation. You can remove the tick for instance

from one of the product streams if you don't want the error in the simulated

values for this stream to influence the parameter fitting.

Selecting the

Streams for

Fitting Error

Assessment

Step 3 Select the streams that are to be used for the fitting process.

If you now select Ball Mill from the Equipment Selection frame and place a tick

in its check-box, the program will automatically select the BM Product from the

Stream Error Selection frame. By default this frame should contain all of the

streams associated with the ball mill - the feed plus the water addition.

However, the default selection for stream error assessment will always be just

the product stream (or streams) from the selected item of equipment; in this case

the BM Product.

This means that fitting of the ball mill parameters will take place by minimising

the difference between the simulated values and the experimental values

associated with the BM Product stream.

Selecting

Parameters for

Fitting

Step 4 Select the parameters to be fitted.

Next you need to select from the central parameters list, the ones that you intend

to be dealing with for this round of fitting.

As you select each parameter from the top centre selection list, you will see that

the chosen parameters will immediately appear in the Parameter Selection

frame below. By default, each of the parameters that is added into the list in this

frame will have its check-box in the lower frame ticked, which means that it is

selected for fitting. You can however, uncheck these check boxes. If you elect to

do this, the parameter concerned will not be fitted, but the guessed value will be

used as a fixed value for the parameter concerned through each simulation

cycle of the fitting process. If on the other hand you were to de-select this

parameter from the top parameter list, then whatever value has been entered for

the parameter in the equipment model window will be the one used as the fixed

value through each round of simulation.

JKSimMet automatically inserts your initial estimate of the parameter value from

the equipment data window into the Guessed Value column. The Scale Factor is

also automatically set at 10% of the initial estimate. If you wish, these values

can be changed by highlighting the existing value and over-typing it with a new

one.


Model Fitting 281

Creating

Parameter Lists

For each model fit case, a parameter list will automatically be saved and this

will consist of whatever parameters you have chosen while this model fit case

was selected. However, in addition to this first parameter list, you can create

any number of extra parameter lists that you can then return to as required. Any

such lists you create will be automatically saved and they will be specific to that

particular model fit case.

Note that the definition of the parameter lists also includes the specification of

which streams are to be used for the model fitting error assessment.

Fitting the Ball

Mill Model

You should next select Ball Mill Only from the Model Fit Case drop-down and

then select all but the last of the parameters (Knot 4), that are associated with the

ball mill model. Note that the ball mill model is actually set via the equipment

window and in this case the perfect mixing model is the one that has been

selected.

There should now be 3 parameters listed in the lower Parameter Selection table.

Deselect the last of these three (Knot 3) by removing the tick from its check-box.

Then place a value (say 2 for example), into the Guessed Value field for this

parameter. This is not necessarily a realistic number to use for this parameter -

just an example to illustrate the principal.

Adjust Model

Fit Settings

Step 5 Adjust the settings for model fitting.

The next step is to adjust the simulation settings for model fitting, if required.

The Settings frame looks like the screen grab below.

The Size Interpolation refers to how data associated with intermediate sizes;

that is sizes other than those actually entered, are to be calculated. The default

setting is Linear, but Spline interpolation may give better results under some

circumstances.

The Starting Condition drop-down is where you select the type of data that are

to be used for the feed to the circuit during each round of the fitting process.

Normally you would start from the experimental data but if you have doubts

about how representative the sample was and if balancing has changed the

values for this sample significantly, then you might want to start from the

balanced values.

Again, for the Error Condition, there is a choice of the data type with which to

compare the simulated values after each round of simulation. Once more the

first choice should probably be to use the experimental data, but if there are

doubts about the samples (in this case the products from the selected circuit),

then balanced data may be a better choice.

The Max Iterations figure here refers the maximum iterations allowed for each

round of simulation during the model fitting sequence. For simulations of a

circuit where there is no circulating load, (as is the case here, where we are



fitting the ball mill alone), only one or two iterations for each round of

simulation would be needed. The maximum iterations limit only becomes

important when you are fitting a larger circuit where there are one or more

circulating loads. Normally the default limit of 100 will be sufficient, but if your

circuit is having problems converging, then you may need to increase this limit.

Convergence refers to how close the simulated values have to be to whichever

data type has been chosen for the error condition, before the model fitting

process has deemed to have converged. The convergence limit value can

normally be left at the default setting.

Run the Ball

Mill Model Fit

Step 6 Run model fitting.

Leave the default settings in place and press the Start button to run the model

fitting. A summary of the results will be shown in the Model Fitting Results

frame, which is immediately below the Settings frame.

Create A

Model Fit Case

for the

Hydrocyclone

Step 7 Set up a model fit case for the cyclone.

Now that model fitting has been run for the ball mill by itself, you should create

another Model Fit Case, this time for the cyclone (call it Cyclone Only), using the

same procedure as was outlined above. After you have created this, select

Cyclone Only from the Model Fit Case drop-down. On doing so you will see that

there is now an item in the Equipment Data Selection frame (far right), which

was empty when we were fitting the ball mill parameters. This frame has an

item in it because the cyclone is selected and a cyclone is an example of an

equipment item that has an operational characteristic which can be measured

and is also predicted by the model. The characteristic we are talking about here

is the cyclone operating pressure. This means that in the case of a cyclone, the

difference between the measured and simulated cyclone pressure can be used in

the same way as the difference between measured and simulated stream

characteristics, to tune the parameters associated with the cyclone model.


Model Fitting 283

Run Cyclone

Model Fitting

Step 8 Run model fitting for the cyclone.

After selecting the cyclone U/F and O/F streams plus the cyclone operating

pressure for the fitting error comparisons, you can again leave the settings at the

default values and run another fit. A screen grab of the Model Fitting window

after fitting the cyclone is shown below.

Run Fitting for

Whole Circuit

Step 9 Run model fitting for the whole circuit.

Once the ball mill and the cyclone have been fitted separately, you can then run

the fitting process for the whole circuit. A screen grab of the Model Fitting

window after fitting the whole circuit is shown below.



7.5.7 Master Slave Fitting

Master/slave model fitting allows the same parameters to be fitted to two or

more units in a single test. The parameters fitted will have the same values for

the master and all the slave units. Master/Slave fitting can be used when

fitting survey data collected simultaneously from parallel units with the same

operating conditions. Alternatively, it can be used for survey data collected

sequentially from a single process unit, where it is expected that model

parameters will not be affected by any change in operating conditions.

Equipment

Selection

The Master/Slave functionality is available in the model fitting dialog when

two or more of the same equipment items use the same model, as shown

below.

In this case the eight cone crushers have the same model.

The choice of which equipment item to use as the master is not important as

all units will finish with the same parameter values. For this example Test 1 is


Model Fitting 285

the master equipment. The first step is to select the parameters in the master

equipment that you wish to use in the slave equipment. In this example the

parameters K1 - Constant, K1 - CSS(mm), K1 - Feed TPH, K1 - F80(mm), K2 -

Constant, K2 CSS(mm), T10 - Constant and Pow Prod Fact have been chosen,

as shown below.

Selecting Test 2 in the equipment list and then selecting Test 1 in the Master

drop down control gives the following selection options in the equipment

parameter list:

The user can now select the parameters chosen for fitting in the master

equipment as parameters for the slave equipment, in effect replacing those

parameters in the slave equipment.

As selected above, Test 2 will use the parameters from the master equipment

and none of its own.

Parameter With the eight parameters already chosen the parameter selection grid will



selection display the following:

The equipment parameters listed are the selected non slave parameters for

each equipment item. The equipment that uses the selected parameter as a

slave parameter is listed in the final column.

Once a piece of equipment has been set as a slave it cannot act as a master to

another equipment item. However, any equipment not set as a slave can be a

master to many other pieces of equipment as shown below where Test 1 is

also the master of Test 3, 4, 5, 6, 7 and 8.

7.5.8 Checking the Fit

During the execution of the fitting program the Model Fitting Results frame of

the Model Fitting window is continually updated as the iteration count

progresses. Assuming that the fitting reaches a satisfactory conclusion, the

standard deviations (SDs) of the parameters will be updated to their final

values when the fitting program stops.

There are various ways in which the user can judge whether the results are

good or bad:

One method is to compare the size (order of magnitude) of the parameter SDs

with that of their associated values. When the SD is small compared with the

value as a ratio, it is a good fit, when large, it is a poor fit.

The summary values in the Model Fitting Results frame also indicate the

success of the fit. Low values in the Residual, Error Sum, and Errors SD fields

indicate a good fit; large values, a poor fit. Moreover, in the case of these fields,

cross comparisons between fittings can be made. If these values are smaller in

the most recent run of the fitting than they were in the previous run, the fit is

getting better. If they are getting larger, you are going in the wrong direction.


Model Fitting 287

The engineer can also judge the relative success of the fitting by looking at the

stream data windows, with Weighted Error and Percentage Error versions of

the difference between calculated and experimental data being the most useful

indicators. These are displayed by selecting the appropriate item from the

Error drop-down list.

The graph plotting facility of JKSimMet allows the engineer to plot raw and

fitted sizing data on the same graph, as detailed in next section - Presentation

of Model Fitting Results.

The overview facility of JKSimMet allows key experimental and calculated

data for multiple streams to be viewed in a summary table. These overviews

are configurable by the user (see the topic under the JKSimMet Windows

section for details).

7.5.9 Presentation of Model Fitting Results

There are two main ways to present the results of model fitting:

Printing data

Plotting graphs

We shall deal with these in turn.

Printing Model

Fit Results

Given that model fitting concerns the experimental (raw) data and the predicted

(fitted) data for streams (mainly), the results presentation should display these

two types of data for the streams concerned, in a manner that facilitates easy

comparisons.

The easiest method of printing data for the individual streams is to go to the

relevant stream data window and follow the steps below.

Step 1 Open the relevant stream data window by double clicking the

stream.

Step 2 Left-click on the Copy Grid icon in the top centre portion of the

stream data window to copy the required data.

Step 3 Open Excel, select an appropriate position for the top left corner of

the data grid to be pasted and then press the Paste button to insert

the data.

Step 4 Repeat Steps 1 to 3 for all the other streams whose data you want to

print.

These steps also apply to any other window that contains data you would like

to print, such as equipment data. In this case you would double-click on the

equipment item rather than on a stream to open the appropriate window.

Once these data have been inserted into an Excel spreadsheet, just use the Excel

facilities for setting out and printing a report.

The

Configurable

Stream

Overview

Window

The Configurable Stream Overview window provides a convenient means of

looking at experimental and model fitted data on the screen and enables the

user to design the layout so that it only shows the data that is currently of

interest and only for the streams that the user has selected. These overviews can

also be printed, using the Print Overview button located on the Configurable

Stream Overview window toolbar. For more information on using the

Configurable Stream Overview, see under the topic heading Viewing the Data -

157



Summaries and Reports .

The Reporting

Feature

The Reporting feature provides a means of printing both stream and equipment

data. The user can configure the report to show experimental and fitted data,

SDs and errors for any streams. (See the section Using the Reporting Feature

for more information on the this feature).

Plotting

Graphs of the

Model Fitting

Results

The graphs presenting model fitting results are once again, of stream data. They

involve experimental (raw) data, and predicted (fitted) data. The graphs are

configured on the Configurable Graphing window, which is opened by pressing

the Config Graph button ( ).

Step 1 Left-click on the Config Graph button on the main JKSimMet toolbar

to bring the Configurable Graphing window into view.

Step 2 For this exercise, you will create a new graph so click on the New

button (circled in screen grab below). Note that the default setting for

the graphing facility will normally have some data pre-selected, so at

this point you can either adjust the settings for this graph or else

create a new one.

Step 3 When you click on the New button, a dialog will open where you

can type in a name for your graph and also specify the type of graph

you require. For the type there are only the two options; Equipment

or Stream. In this case we will create a graph showing the new feed

plus the cyclone products.

Step 4 Move the cursor to the top row (where the row heading is Stream).

213

226


Model Fitting 289

When you click on this cell, (which should initially contain the word

"None"), a drop-down list will appear with all the available streams

from your flowsheet. Select Cyclone Feed from this drop-down.

Once you have selected the stream, you will find that all of the

previously grey cells below the stream selection cell will now be

white and editable. In fact they all contain drop-down lists through

which you can select the type of data to be plotted and also set up

the characteristics of the display for this data set.

Step 5 Select Cum% Passing from the drop-down list in the Format cell,

immediately below the cell for stream selection. Leave the Display

cell on the default of Show. The option of Hide is available to provide

you with the ability to temporarily remove any of the data sets you

have configured for plotting on the current graph.

Step 6 The cell in the Data row allows you to select individual data types or

combinations of data types. Select Exp & Fit from the drop-down list

to compare your fitted results with the experimental data.

Step 7 Leave the display characteristics of Line, Point and Colour at their

default settings.

Step 8 You can then select Cyc U/F for the next column and Cyc O/F for the

third column.



Step 9 Note that when you have multiple columns set up, you can set all

the Format and Data fields to the same values using the drop-down

lists immediately above the tabulated data.

Step 10 Once the columns of the grid have been set up, you can view the

graph by simply switching from the Stream tab to the Graph tab.


Model Fitting 291

7.5.10 Problems Related to Model Fitting and Possible Solutions

There are of course many problems that may be encountered during model

fitting. It is possible, however, to point out some of the more common mistakes,

so that you are aware of them.

Errors, Warnings,

Faults

Some problems detected by JKSimMet will produce error messages. Generally

these error messages will have a description of the problem that has occurred.

Skill versus

Practice

Model fitting is not a cut and dried procedure. The only way to acquire a

useful skill level is to practice on a wide range of real data. JKSimMet offers a

user-friendly environment for what are really very complex and powerful

mathematical techniques.

Initial Parameter

Estimates

As with all non-linear least squares programs, Model Fitting is sensitive to

initial parameter estimates. The default values and the supplementary

information provide a useful guide. However, trial and error may be necessary

to find the best estimates to use with a new circuit or new data.

Graphical

Analysis

The graph capability of JKSimMet is the most powerful way to examine your

data fit. Discontinuities in size distributions highlight poor data or a change

in measurement technique. Graphical analysis also highlights any bias in the

data fit.

Different Size

Measurement

Techniques

Be very careful of changes in size measurement technique, such as from sieves

to Cyclosizer.

No Apparent

Progress

When nothing much seems to be happening in model fitting, a simple first

check is to ensure that you have a reasonable Maximum Number of Steps

setting, and that the streams and parameters that you intend to include in the

fitting are selected with a tick in the Parameters section of the Model Fitting

window.

Data Note that it is necessary to have as much feed and product data as possible for

each of the unit Models to be tuned. Simulation requires only feed data, but

fitting must have some product data as well.

Not Enough Data Even when you have the necessary data to perform model fitting, it is essential



to ensure that there are enough readings to be useful for fitting; in general

terms, the more data the better.

SDs and

Emphasis

The SD settings in the stream data window may be set so that they can cause

such an over-emphasis on one parameter that the potential of the fitting is

compromised. Always try to make the SDs as good an estimate as possible.

Scale Factors The Scale Factor in the Parameters section of the Model-Fit window can also

be a source of problems. If the scale factor is too big the fitting may stop,

because any adjustment in the parameter produces such a large change that it

steps over the minimum of the sum of squares. On the other hand, however, if

the scale factor is too small, the fitting may stop because any adjustment

produces a change of so small a scale as to be judged insignificant, even

though you may not be close to a minimum point. So, be very careful with

scale factors. As a guide, perhaps a scale factor one-tenth of the magnitude of

the parameter estimate would be a reasonable place to start.

Parameter

Problems

The last chapter contains model descriptions, default values and a section

on fitting for each specific model. The comments contained in these sections

may help to overcome any misunderstandings or other problems you may

have with the model parameters.

Large Weighted

Errors

Examine the weighted errors carefully. These often indicate suspicious data

points. A typical example is a screen top size that contains several times the

predicted weight, because the laboratory screen stack did not extend to a large

enough top size. Set the error to missing for this fraction to fix the problem.

Knot Positions Where spline functions are used, the knot values can usually be fitted, but not

the knot positions.

These models provide a fairly smooth response because of the use of spline

functions. A simple guide to knot positioning is that knots should be selected

wherever a bend is needed. After all, the spline function is a mathematical

model of a draftsman’s spline curve - a thin strip of steel with screw positions

which are equivalent to spline knots.

7.5.11 References

GY, P.M., 1982. Sampling of Particulate Materials: Theory and Practice, 2nd

Ed. Elsevier, Amsterdam.

LYMAN, G.J., 1986. Application of Gy's Sampling Theory to Coal,

International Journal of Mineral Processing, 17, pp 122.

LYNCH, A.J., 1977. Mineral Crushing and Grinding Circuits, (Elsevier,

Amsterdam).

NAPIER-MUNN, T.J., MORRELL, S., MORRISON, R.D., & KOJOVIC, T. 1996.

Mineral Comminution Circuits – Their Operation and Optimisation. JKMRC

Monograph Series in Mining and Mineral Processing 2. Series Editor T.J.

Napier-Munn, Julius Kruttschnitt Mineral Research Centre, University of

Queensland.

294

Part

VIII



8 Model Descriptions

In this chapter, details are provided for all of the models that are available in

JKSimMet. The models are grouped and described under the major plant

section headings.

This chapter contains:

• A description of each model available in JKSimMet

• Instructions for the use of each model

• Key equations that constitute the mathematical basis of the models

• A list defining the symbols used in the model equations

• Any known limitations and restrictions

• Any relevant references where the user could go for further information

• Typical model parameter values, where appropriate.

There are a number of generic models included in JKSimMet which can be

used to describe the behaviour of a wide range of processes. For example the

mass re-allocation model can be used to describe any sort of device in which

the ore feed properties are changed, such as a reagent addition point or a ball

mill. Selection of parameters for these models will depend entirely on the type

of process being modelled.

Most of the process units available to the user when drawing the flowsheet can

be described by a number of models. Typically, a process unit will have a

specific model, developed for that particular device, and a number of generic

models. Selection of the appropriate model is at the user’s discretion and will

often depend on the available test data.

8.1 General Models

General Models This topic contains a description of all the general process models available in

JKSimMet that do not fit in one of the more specific process type category

headings below.

The splitter models described here provide splitters of varying complexity,

from a simple mass split into two products (810) or into three products (870),

independent mass splits of solids and water (811) and a split generating a

specific volume flow rate to one of the products (812).

8.1.1 Ore Feeder (1300)

Ore Feeder The ore feeder (called Feed) is a specialized piece of equipment that has a

single product. The feed unit allows you to set up the flowsheet ore SG and the

starting size distribution.

The size markers, i.e. the percent passing a particular size and the size at a

particular percent passing, can be set by double clicking on those fields in the

Totals tab. Note that while the flowsheet properties dialog allows you to set

global properties for Data Information blocks and for the tools such as

Simulation and Model Fit, these properties for the feeder and ports may be set

at different values for each.

Version 6.0.1 - March 2014 General Models

Model Descriptions 295

8.1.2 Water Feeder Models (1251 & 1252)

Water Feeder

Models

This topic contains a description of the Water Feeder models available.

8.1.2.1 Model Description - General

Equipment The Water Feeder is specialized equipment that is the source of water

additions to a flowsheet. The Water Feeder is characterized by the fact that it

has no feed streams and one product stream that is made up of water only.

The Liquid Feeder replaces the "Unit Feed Density" section of each model in

JKSimMet Version 4. The three models provided with the Liquid Feeder are

functionally identical to the three options for "Unit Feed Density". The

functioning of these models is described below.

There are two ways in which the Water Feeder can be defined:

1. Water Feeder – Required % Solids – Standard.

2. Water Feeder – Water Addition – Standard.

These model choices are only available for the Water Feeder equipment.

After opening the Equipment window for the Water Feeder equipment, click on

the Equipment model drop down list to access these choices. Then click on the

double arrow button to the right of the drop down list to open the model

window pertaining to the selected model.

8.1.2.2 Required % Solids - Standard Model

Model Overview The Water Feeder – Required % Solids – Standard model is used when water is

to be added so that the stream percent solids feeding a piece of equipment

equals that specified by the user.

This option allows the user to set a maximum % solids for the total feed to the

connected equipment.

If the feed % solids is higher than the "Required % Solids" then the liquid

feeder adds additional liquid to achieve the required % solids.

If the % solids value is already lower than required, the liquid feeder adds no

liquid. It does NOT remove liquid to achieve the required value.

Model Data Input Double click on the appropriate field in the table and type in the required value

for the parameter:

• Required Percent Solids (%)

During simulation, JKSimMet calculates:

• New Water Addition (m3/h)

such that the percent solids of the combined streams flowing into the

equipment to which the water is added, equals that specified by the user. The

other values in the table are also calculated by JKSimMet during simulation

and relate to the combined stream that flows into the equipment:

• Solids Flow (tph)

• Water Flow (m3/h)

• Percent Solids (%)

Version 6.0.1 - March 2014General Models


• Volume (m3/h)

If during simulation the new water addition calculated by JKSimMet would be

negative, the new water addition value will be set to zero.

A typical Required % Solids tab for the Water Feeder is shown below.

Water Feeder – a typical Required % Solids – Standard tab

8.1.2.3 Water Addition - Standard Model

Model Overview The Water Feeder – Water Addition – Standard model is used when a user

defined volume of water is to be added.

Liquid Addition is the recommended mode for common use. The user specifies

the required liquid addition rate in cubic metres per hour.

This option has two more uses. The experimental liquid addition may be used

as a parameter in model fitting. That is, a model fit may use liquid addition as a

parameter when liquid flows were not measured or the measurement was

dubious. The "exp Liquid Addition" is subject to optional update after the model

fit, as are all other parameters.

Note that % solids or water flow from the circuit should be constrained by a

small SD value to provide a constraint on total water addition.

The third use of this option is for mass balancing of liquid additions.

The user provides the "exp New Liquid Addition" and an SD estimate for this

model. The other requirement is that the Liquid Feeder and Liquid are selected

on the Select Tab of the Mass Balance Tool.

The balanced liquid addition is returned to the Calc* field of the Liquid Feeder.

If you wish to use this value for fitting or simulation, copy it into the appropriate

Exp value.

Model Data Double click on the appropriate field in the table and type in the required value



Input for the parameter:

• New Water Addition (m3/h)

The other values in the table are calculated by JKSimMet during simulation and

relate to the combined stream that flows into the equipment unit to which the

water is added:

• Solids Flow (tph)

• Water Flow (m3/h)

• Percent Solids (%)

• Volume (m3/h)

A typical Water Addition tab for the Water Feeder is shown below.

Water Feeder – a typical Water Addition – Standard tab

8.1.2.4 Model Limitations

Two Water Feeders with the Required % Solids – Standard model selected

cannot be used to add water to a single water addition point on a flowsheet.

This is because the Required % Solids model calculates the volumetric flow of

water to be added by taking into account the percent solids of all of the streams

that combine to flow into the equipment to which the water is added. If there

are two Water Feeders with the Required % Solids model adding water to one

equipment item, the amount of water added by each water feeder to obtain the

required percent solids of the combined equipment feed cannot be calculated.

8.1.2.5 References

No relevant references.



8.1.3 Hydrocyclone Models (200, 201)

Hydrocyclone

Models (200 and

201)

This topic contains a description of the Hydrocyclone models 200 and 201.

8.1.3.1 Desciption

The model is based on the concept of a reduced efficiency curve, which in turn

is developed from the actual efficiency curve and the corrected efficiency curve

for the classifier treating a particular ore. The important concept is that the

reduced efficiency curve is a characteristic function of an ore and is

independent of the dimension or operating conditions of the cyclone. A

typical set of efficiency curves for a cyclone is shown in the first figure of

the next section.

The model consists of a series of equations which are described below. At

least one cyclone test on a particular ore is required to provide data for the

calculation of constants in the equations.

8.1.3.2 Equations

The model consists of a series of equations, which are described below.

Pressure -

Throughput

Relationship

The pressure-throughput relationship can be expressed as:

Q = KQ2

Dc2 (P/

p)0.5 (D

o/D

c)0.68 (M200.1)

where

KQ2

= KQ1

(Di/D

c)0.45 ( )-0.1 (L

c/D

c)0.2 (M200.2)

The proportionality constant, KQ1

, is a function of the feed material and the

diameter of the cyclone. For cyclones of Krebs design, treating identical feed

solids, the dependence on cyclone diameter may be empirically represented by

the equation

KQ1

= KQ0

Dc-0.1 (M200.3)

where KQ0

depends on feed solids characteristics (eg. specific gravity) only.

Classification

Size

Relationship

For normal industrial operation, the classification size can be related to the

variables according to the equation

d50c

/Dc = K

D2(D

o/D

c)0.52 (D

u/D

c)-0.47 0.93(P/{

p g D

c})-0.22 (M20

0.4)

where KD2

is related to the minor design variables Di, L

c and q by

KD2

= KD1

(Di/D

c)-0.5(L

c/D

c)0.2 ( )0.15 (M200

.5)

and KD1

may be written as

KD1

= KD0

(Dc)-0.65 (M200

298



.6)

KD0

depends on feed solids characteristics only (such as size distribution and

specific gravity).

(Note that the classification sizes for specific minerals within the feed stream

can be estimated using the following formula:

where FeedSG is the mean feed solids density, d50c

is the overall corrected d50

,

MineralSG is the density of the specific mineral of interest, and d50c

(m) is the

corrected d50

of the mineral of interest.)

Recovery to

Underflow

Relationships

Water recovery (Rf) and volume pulp recovery (R

v) to underflow are related to

the major variables by:

Rf = K

w2(D

o/D

c)-1.19 (D

u/D

c)2.40 (P/{

p g D

c})-0.53 ( )0.27 (M200.7)

and

Rv= K

v2 (D

o/D

c)-0.94 (D

u/D

c)1.83 (P/{

p g D

c})-0.31 (M200.8)

Further, the effects of inlet diameter, cone angle and cylinder length have been

evaluated as

Kw2

= Kw1

(Di /D

c)-0.50 ( )-0.24 (L

c/D

c)0.22 (M200.9)

and

Kv2

= Kv1

(Di/D

c)-0.25 ( )-0.24 (L

c/D

c)0.22 (M200.10

)

Here Kw1

and Kv1

are constants also depending on feed solids characteristics.

The current data indicate that Kw1

and Kv1

are independent of cyclone

diameter for geometrically similar cyclones treating identical feed solids.

Small quantities of viscosity modifiers such as clay, can have a marked effect

on these variables.

Efficiency Curve

Relationship

The efficiency curve used in this model is given below:

Eo(d/d

50c) =

C.(1+ . *.d/d50c

) (exp( ) - 1)/(exp( . *d/d50c

) + exp( ) - 2)

(M200.

11)

When is 0, * is 1 the above equation reduces to

Eo(d/d

50c) = C.(exp( ) - 1)/(exp( .d/d

50c) + exp( ) - 2) (M200.12)

The shape parameter determines the initial rise, while determines the

slope at larger values of d (d d50c

). Both and are normally constant for

given feed solids, while C and d50c

vary with cyclone dimensions and

operating conditions. The parameter * is determined, for given values of

and , by the condition that



Eo.(1) = C/2 (M200.13)

* is calculated iteratively in the model.

The first two figures below show the effects of and on the shape of the

efficiency curve.

Modified

Efficiency Curve

An alternative to the standard efficiency curve is available with the

Nageswararao Fines hydrocyclone model.

With this model the user can specify the value of the reduced efficiency curve

(ie. fraction reporting to overflow) at 33% and 66% of the d50c

size.

The curve is fixed (by definition) at the 100% point for zero size and at the

d50c

. A cubic spline curve is used to describe the efficiency curve for sizes

below the d50c

point. For sizes larger than the d50

, a log-normal distribution

curve is used. The log-normal curve is determined so that there is no

discontinuity in slope at the d50c

point.

The third figure below shows how the modified efficiency curve works. The

user needs to specify (or model fit) the values of the curve at 33% and 66% of

the curve only.

The other parameters used by the model are used in the same way as the

standard Nageswararao model.

The Nageswararao-Fines model is useful for describing asymmetric efficiency

curves where a long 'tail' exists for either coarse or fine material.

Interactions The interactions of variables within a cyclone are complex. Refer to Summary

Table section for a summary of interaction dependencies.

Scaling Facilities for scaling the operation of the hydrocyclone are built into the

model.

Figure M200.1 - Effect of Alpha on Reduced Efficiency Curve

305



Figure M200.2 - Effect of Beta on Reduced Efficiency Curve

Figure M200.3 - Efficiency Curve for Nageswararao-Fines Model

8.1.3.3 Symbols

Symbols Symbol Meaning

reduced efficiency curve sharpness parameter

reduced efficiency curve hook parameter

* reduced efficiency curve calculated parameter

C 100 - Rf or recovery of water to overflow, %

Dc cyclone diameter, m



Di diameter of circle with the same area as cyclone inlet, m

Do diameter of circle with the same area as vortex finder, m

Du diameter of circle with the same area as spigot, m

Eo(d) percentage of feed material of size d reporting to overflow

g gravitational acceleration

KD constant in the classification size relationship

KQ constant in the volume pulp recovery relationship

Kv constant in the volume pulp recovery relationship

Kw constant in the water recovery relationship

Lc length of cylindrical section, m

P feed pressure at inlet, kPa

Q cyclone throughput, m3/hr

Rf recovery of water to underflow, %

Rv volumetric recovery of feed pulp to underflow, %

d mean size of particle, mm

d50c size of a particle in feed which has equal probability of going tounderflow or overflow, due to centrifugal action, mm

Cv volumetric fraction of solids in feed slurry

Cv Cv

p density of feed pulp, tonnes/m3

cone full angle, degrees

8.1.3.4 Restrictions

Restrictions As the feed becomes coarser, d50c

tends to decrease even when all the other

variables are kept constant. The effect of size distribution of the feed

material becomes insignificant when the feed consists of mainly –53 mm

particles, and also when the proportion of –53 mm particles is less than

25% of the feed solids.

The analytical form used does not provide a perfect representation for the

reduced efficiency curve. As a result the model often tends to predict fewer

coarse particles in the overflow than occur in real operation, however, the

magnitude of the error is considered to be small.

Viscosity variations due to changes in pulp density are largely accounted

for by the model. Viscosity variations caused by variable quantities of

slimes affect the parameters in quite a systematic way.

As viscosity (or slimes fraction) increases, the cut size becomes coarser, the

water split to overflow is reduced, and the cyclone pressure drop becomes

larger. However, the reduced efficiency curve remains relatively constant

until the onset of roping.



The model may be used to estimate operation during roping:

o the cut size will become 5 to 10 times larger (ie. multiply KD0

by 5 to 10

times

o the efficiency curve will become an “inefficiency” curve with an value

typically of 0.1 - 0.2.

o water split and pressure drop are relatively unaffected although a small

drop in pressure is often claimed. This may result from a reduced

volume of solids to overflow.

The onset of cyclone roping is difficult to predict. In general 50% solids by

volume is a practical underflow limit. However, very coarse underflow may

achieve higher density and finer ones somewhat lower density as detailed

below.

JKSimMet will warn you that roping is likely if either of the density limits

(detailed below) are exceeded.

Cyclone Roping

Constraint

If the cyclone feed density is less than 35% solids by volume, the SPOC

constraint (Laguitton 1985) is claimed to predict onset of roping.

Vol % solids in U/F = Limiting Vol % solids (~56) + 0.2 (Vol % Solids in Feed -

20)

The limiting % solids is defined as the onset of roping at a volumetric feed

density of 20%.

In tabular form:

Table M200.1 - Cyclone Roping Conditions

at sg 2.7 at sg 4.0

Feed

Density

Underflo

w Density

Feed

Density

Underflo

w Density

Feed

Density

Underflow

Density

% by Volume % by Weight % by Weight

5 53 12.4 75.3 17.4 81.8

10 54 23.1 76.0 30.8 82.4

15 55 32.3 76.7 41.4 83.0

20 56 40.3 77.5 50.0 83.6

25 57 47.4 78.2 57.1 84.1

30 58 53.6 78.8 63.1 84.7

35 59 59.2 79.5 68.3 85.2

Empirical

Constraint

Industrial experience demonstrates that a coarse underflow will remain in

spray discharge at a higher density than a fine underflow. This is intuitively

reasonable in terms of slurry viscosity but difficult to predict.

Plitt et al (1987) have developed an empirical relationship based on Lynch

(1965) data and others.



Vol % Solids in U/F = 62.3 *

This approach puts a 50% solids by volume limit on an underflow with 50%

passing 100 µm and 60% at a P50 of around 200 µm. This function decreases

sharply with size dropping to 45% solids by volume at a P50 of 80 µm and

40% at a P50 of 60 µm.

In tabular form:

Table M200.2 - Cyclone Roping Conditions - Accounting for Coarseness

Roping onset

% Solids by Vol.

Underflow

50% passing

(mm)

% Solids

at sg 2.7

% Solids

at sg 4.0

35.2 50 59.4 68.5

39.0 60 63.3 71.9

45.9 80 69.6 77.2

50.5 100 73.4 80.3

53.9 120 75.9 82.4

58.6 170 79.3 85.0

60.0 200 80.2 85.7

61.3 250 81.0 86.4

The two effects are probably competitive to some degree. Further, each

operation has a 'comfort limit' on cyclone underflow density which may be a

good deal lower than the above limits.



8.1.3.5 Printouts

Nageswararao

(Model 200)

Nageswararao -

Fines (Model 201)

8.1.3.6 Summary

Summary of the

Effects of

Variables on

Cyclone

Operation

Table M200.3 - Effects of Variables on Cyclone Operation

Variable

IncreasedQ

Resultant Effect on Parameter

d50c

Rf

Rv

Dc increase (0.57) increase (0.82) decrease (-0.4) decrease (-0.55)

Di increase (0.45) decrease (0.5) decrease (-0.5) decrease (-0.25)



Do increase (0.68) increase (0.52) decrease (-1/19) decrease (-0.94)

Du - decrease (-0.47) increase (2.4) increase (1.83)

Lc increase (0.2) increase (0.2) increase (0.22) increase (0.22)

p increase (0.5) decrease (-0.22) decrease (-0.53) decrease (-0.31)

- increase (0.93) increase (0.27) -

p decrease (-0.5) increase (0.22) increase (0.53) increase (0.31)

decrease (-0.1) increase (0.15) decrease (-0.24) decrease (-0.24)

Note: The numbers listed in brackets are exponents for dependence of the

parameter on the variable.

Examples of the effects of and on reduced efficiency curves are given in the

figures in the Model Equations topic. The * parameters used in the model

are calculated.

8.1.3.7 Fitting the Cyclone Model (200)

Parameter Menu

Pressure Data If you wish to predict cyclone pressure accurately at other conditions you will

need at least one accurate pressure measurement and a set of at least two out

of three of the feed, underflow and overflow samples.

If pressure data are not available, an approximate pressure can be estimated

from the manufacturers published data.

The calculated pressure is used in the equations for classification size and

recovery to underflow. Hence, the cyclone pressure is an important

measurement.

The measured or assumed pressure data must be entered on the Performance

Data tab of the cyclone equipment data window. If an accuracy estimate is

available, use it to calculate the standard deviation. If not, use 10% of the

pressure value.

The capacity constant KQO

can be calculated from the cyclone flow rate and

the cyclone dimensions. (Refer to equations M200.1-M200.3).

Typical values of KQO

are in the range 300-600. The scale factor for fitting

should be 100.

To make the pressure observation available to the fitting calculation, it must

be selected with a tick on the Equipment Data tab of the Model Fit dialogue

window

Classification

Size (KDO)

Equations M200.4 to M200.6 define the cut size. KDO

is typically a small

number - say 0.001 to .00001. Therefore, a scale factor of 0.0001 is usually

suitable.

298



Water Split % to

O/F (Cal WS)

The actual water split to overflow (Cal WS) is fitted rather than the two

parameters, KV1

and KW1

, which are defined by a single water split.

When model fitting a single set of cyclone data, ALWAYS fit Cal WS. A good

starting point is 50% with a scale factor of 5.

After fitting, the calculated values of KV1

and KW1

are displayed on the

cyclone equipment data window (Model Parameters tab).

Efficiency Curve

( and )

The reduced efficiency curve is an "S" shaped function as shown in the figure

in the Model Equations topic.

Typical values of range from 0.5 to 4. Beyond 5, the efficiency curves become

very sharp and larger numbers are not significant. A good initial estimate is

2.0.

The factor modifies the "S" curve to add an additional "hook" - or a negative

portion to the actual efficiency curve. A typical value is zero. However, a

poor fit at fine sizes can be tested by trying values of of 0.01 to 0.5. Fitting of

is available but not recommended. A scale factor of 0.1 is suitable once a

good initial estimate has been found by trial.

If the efficiency curve is a poor fit at coarse sizes, try the alternative fines

modified or spline efficiency curve models.

Master/Slave

Fitting

Multiple sets of cyclone data can be model-fitted using the Master/Slave

facility, with one important provision. The water split (Cal WS) cannot be

fitted using Master/Slave fitting.

Fit KD0

, KQ0

, and Cal WS for each data set independently, and determine the

average values of KV1

and KW1

for each cyclone data set from the fit. Use the

average values of KV1

and KW1

in each cyclone data set. Use Master/Slave to

fit KD0

, KQ0

, and (if required) , over all data sets.

8.1.3.8 Fitting the Nageswararao Fines Model (201)

Parameter Menu

The comments in the topic above apply equally to Model 201 except for the

Efficiency Curve parameters a and b which are replaced by Eff @ 0.33 (of d50c)

and Eff @ 0.66 (of d50c).

Typical values are 0.85 and 0.65 respectively.

8.1.3.9 References

DE KOOK, S.K., 1956, Symposium on recent developments in the use of

hydrocyclones - a review J. Chem. Metal. Min. Soc. S.Afr., Vol.

56:281-294.

KAVETSKY, A., 1979. Hydrocyclone modelling and scaling. JKMRC report to

AMIRA, November.

298



KELSALL, D.F., 1953. A further study of the hydraulic cyclone. Chem. Eng.,

Sci., Vol. 2:254-273.

LAGUITTON, D. (Ed), 1985. The SPOC Manual Simulated Processing of Ore

and Coal, CANMET EMR Canada, Ch. 5.1 (Part B).

LYNCH, A.J. 1965. The characteristics of hydrocyclones and their application

as control units in comminution circuits, AMIRA Progress Report

No. 6, University of Queensland (unpublished).

LYNCH, A.J. and RAO, T.C., 1965. Digital computer simulation of

comminution systems. Proc. 8th Comm. Min. Metall. Congr., Aust.,

N.Z., Vol. 6:597-606.

NAGESWARARAO, K., 1978. Further developments in the modelling and

scale-up of industrial hydrocyclones. Ph.D. Thesis (unpublished).

University of Queensland.

PLITT, L.R., FLINTOFF, B.C. and STUFFCO T.J., 1987. Roping in

hydrocyclones. 3rd International Conference on Hydrocyclones,

Oxford England, Elseveir, pp21-23.

YOSHIOKA, N. and HOTTA, Y., 1955. Liquid cyclone as a hydraulic

classifier. Chem. Eng. Jpn., Vol. 19:632-640.

8.1.4 Narasimha-Mainza Cyclone Model (221)

8.1.4.1 Description

Like the Nageswararao model, the Narasimha-Mainza model is based on the

concept of a reduced efficiency curve, which in turn is developed from the actual

efficiency curve and the corrected efficiency curve for the classifier treating a

particular ore.

The model consists of a series of equations which are described below. At least

one cyclone test on a particular ore is required to provide data for the

calculation of constants in the equations.

The form of the equations was given by Narasimha (2009). The exponents differ

slightly from those reported in his thesis, as the model has since been refitted

with a larger data set.

8.1.4.2 Equations

The model consists of a series of equations which are described below.

Pressure -

Throughput

Relationship

The pressure-throughput relationship can be expressed as:



(

M

2

2

1

.

1

)

where

(M221.1)

The proportionality constant, KQ0

, is a function of the feed material and

depends on feed solids characteristics (e.g. specific gravity) only.

fv

is the volume concentration of solids in the feed.

Classification

Size

Relationship

For normal industrial operation, the classification size can be related to the

variables according to the equation

where:

and:

f38

is the mass percentage of -38µm particles in the feed.

(M22

1.3)

(M22

1.4)

(M22

1.5)



Recovery to

Underflow

Relationships

Water recovery (Rf) to underflow is related to the major variables by:

where:

and:

(

M

2

2

1

.

6

)

(

M

2

2

1

.

7

)

(

M

2

2

1

.

8

)

Efficiency Curve

Relationship

The efficiency curve used in this model is identical to that used in the

Nageswararao model

( equations M200.11, M200.12 and M200.13), but with the given by:



(

M

2

2

1

.

9

)

8.1.4.3 Symbols

Symbols Symbol Meaning


reduced efficiency curve hook parameter


C 100 - Rf or recovery of water to overflow, %

d mean size of particle, mm

d50c

size of a particle in feed which has equal probability of goingunderflow or overflow, due to centrifugal action, mm

Dc cyclone diameter, m

Di diameter of circle with the same area as cyclone inlet, m

Do diameter of circle with the same area as vortex finder, m

Du diameter of circle with the same area as spigot, m

Eo(d) percentage of feed material of size d reporting to overflow

f38 mass percentage of -38 µm particles in the feed

g gravitational acceleration

i angle of inclination of the cyclone, degrees

Kd0

constant in the classification size relationship

KQ0 constant in the volume pulp recovery relationship

K 0 constant in the relationship

Kw0 constant in the water recovery relationship

Lc length of cylindrical section, m



P feed pressure at inlet, kPa

Q cyclone throughput, m3/hr

Re Reynolds Number

fdensity of feed fluid, tonnes/m3

pdensity of feed pulp, tonnes/m3

sdensity of feed solids, tonnes/m3

Rf

recovery of water to underflow, %

cone full angle, degrees

Vi

inlet velocity

8.1.4.4 Printout

Narashima-

Mainza

(Model 221)



8.1.4.5 Restrictions

Restrictions · For the Nageswararao model, as the feed becomes coarser, d50c

tends to

decrease even when all the other variables are kept constant. The effect of size

distribution of the feed material becomes insignificant when the feed

consists of mainly –53 mm particles, and also when the proportion of – 53 mm

particles is less than 25% of the feed solids.

For the Narasimha/Mainza model, it is not known if this effect exists.

However, it is likely that there is still a feed size effect on d50c

.

· The analytic form used does not provide a perfect representation for the

reduced efficiency curve. As a result the model often tends to predict fewer

coarse particles in the overflow than occur in real operation, however, the

magnitude of the error is considered to be small.

· Viscosity variations due to changes in pulp density are largely accounted

for by the model. Viscosity variations caused by variable quantities of

slimes are also accounted for by the model.

· The model may be used to estimate operation during roping:

– the cut size will become 5 to 10 times larger (i.e. multiply KD0

by 5 to 10

times

– the efficiency curve will become an “inefficiency” curve with an a value

typically of 0.1 - 0.2.

– water split and pressure drop are relatively unaffected although a small

drop in pressure is often claimed. This may result from a reduced volume

of solids to overflow.

· The onset of cyclone roping is difficult to predict. In general 50% solids by

volume is a practical underflow limit for vertically mounted hydrocyclones.

However, very coarse underflow may achieve higher density and finer

ones somewhat lower density as detailed below. The Narasimha/Mainza

model does incorporate the effect of angle of inclination and this will affect

the roping point.

JKSimMet will warn you that roping is likely if either of the density limits

(detailed below) are exceeded.

Cyclone

Roping

Constraint

For vertically mounted hydrocyclones, if the cyclone feed density is less

than 35% solids by volume, the SPOC constraint (Laguitton 1985) is claimed

to predict onset of roping. The effect of angle of inclination incorporated in

the model is NOT included in this prediction of roping.Vol % solids in U/F = Limiting Vol % solids (~56) + 0.2 (Vol % Solids in

Feed -20)The limiting % solids is defined as the onset of roping at a volumetric feed

density of 20%.

In tabular form:

at sg 2.7 at sg 4.0



Feed

Den

sity

Underf

low

Densit

y

Feed

Densit

y

Underfl

ow

Density

Feed

Densit

y

Underf

low

Densit

y

% by Volume % by Weight % by Weight

5 53 12.4 75.3 17.4 81.8

10 54 23.1 76.0 30.8 82.4

15 55 32.3 76.7 41.4 83.0

20 56 40.3 77.5 50.0 83.6

25 57 47.4 78.2 57.1 84.1

30 58 53.6 78.8 63.1 84.7

35 59 59.2 79.5 68.3 85.2

Empirical

Constraint

Industrial experience demonstrates that a coarse underflow will remain in

spray discharge at a higher density than a fine underflow. This is

intuitively reasonable in terms of slurry viscosity but difficult to predict. The

effect of angle of inclination incorporated in the model is NOT included in

this prediction of roping.

Plitt et al (1987) have developed an empirical relationship based on Lynch

(1965) data and others.

Vol % Solids in U/F = 62.3 This approach puts a 50% solids by volume limit on an underflow with 50%

passing 100 µm and 60% at a P50 of around 200 µm. This function

decreases sharply with size dropping to 45% solids by volume at a P50 of 80

µm and 40% at a P50 of 60 µm.

In tabular form:

The two effects are probably competitive to some degree. Further, each

operation has a 'comfort limit' on cyclone underflow density which may be a

good deal lower than the above limits.



Co

mp

aris

on

wit

h

Na

ges

wa

rar

ao

In preparing the Narasimha/Mainza model for inclusion in JKSimMet,

JKTech has conducted a series of comparisons with the older Nageswararao

model. In most cases, the responses to changes in operating variables are

similar between the two models. However, the effect of Di on d

50c is quite

different. The reason for the difference is that in Narasimha/Mainza, the

major effect of on Di

on d50c

is in the calculation of Reynolds Number (Re)

which depends on inlet velocity (Vi) which depends in turn on Di.

Nageswararao does not consider Re, the effect of which is very strong in

Narasimha/Mainza and outweighs the direct effect of Di which is similar in

both models. The validity of this major change in response is currently

being investigated by CFD modelling.

8.1.4.6 Summary

Summa

ry of the

effects

of

variable

s on

cyclone

operatio

n

Examples of the effects of a and b on reduced efficiency curves are given in the

attached Figures A2.1 and A2.2. The b* parameters used in the model are

calculated.

8.1.4.7 Fitting the Cyclone Model 221

Parameter

Menu



Pressure Data If you wish to predict cyclone pressure accurately at other conditions you will

need at least one accurate pressure measurement and a set of at least two out

of three of the feed, underflow and overflow samples.

If pressure data are not available, an approximate pressure can be estimated

from the manufacturers published data.

The measured or assumed pressure data must be entered on the Performance

Data tab of the cyclone equipment data window. If an accuracy estimate is

available, use it to calculate the standard deviation. If not, use 10% of the

pressure value.

The capacity constant KQ0

can be calculated from the cyclone flowrate and the

cyclone dimensions. (Refer to equations A2.14-A2.15).

Typical values of KQ0

are in the range 100 - 600. The scale factor for fitting

should be 100.

To make the pressure observation available to the fitting calculation, it must be

selected with a tick on the Equipment Data tab of the Model Fit dialog window

Classification

Size (KDO

)

Equations A2.16 to A2.18 define the cut size. KDO

is typically a small number

- say 0.001 to .05. Therefore, a scale factor of 0.001 is usually suitable.

Water Split % to

U/F (KW0

)

Equations A2.19 to A2.21 define the recovery of water to the underflow. KW0

is typically –in the range 0.01 – 4.0. Therefore, a scale factor of 1.0 is usually

suitable. The model is particularly sensitive to this parameter so it may be

necessary to try several different starting estimates for model fitting to be

successful.

Efficiency Curve

( and )

The reduced efficiency curve is an "S" shaped function as shown in the figure

M200.1.

Equation M221.9 defines the alpha parameter. Ka0

is typically –in the range 1

to 80. Therefore, a scale factor of 1.0 is usually suitable.

Typical values of a a range from 0.5 to 4. Beyond 5, the efficiency curves

become very sharp and larger numbers are not significant. A good initial

estimate is 2.0. a is calculated from Equation M221.9.

The b factor modifies the "S" curve to add an additional "hook" - or a negative

portion to the actual efficiency curve. A typical value is zero. However, a poor

fit at fine sizes can be tested by trying values of b of 0.01 to 0.5. Fitting of b is

available but not recommended. A scale factor of 0.1 is suitable once a good

initial estimate has been found by trial.

If the efficiency curve is a poor fit at coarse sizes, try the alternative models.

Master/Slave

Fitting

Multiple sets of cyclone data can be model-fitted using the Master/Slave

facility.

Use Master/Slave to fit KD0

, KQ0

, KW0

Ka0

and (if required) b, over all data

sets.



8.1.4.8 References

LAGUITTON, D. (Ed), 1985. The SPOC Manual SimulatedProcessing of Ore and Coal, CANMET EMR Canada, Ch. 5.1 (PartB).

NARASIMHA, M., 2009. Improved Computational And EmpiricalModels Of Hydrocyclones, PhD Thesis, University of Queensland(unpublished)

PLITT, L.R., FLINTOFF, B.C. and STUFFCO T.J., 1987. Roping inhydrocyclones. 3rd International Conference on Hydrocyclones,Oxford England, Elseveir, pp21-23.

8.1.5 Screen Models (215, 230 & 235)

Screen Models This topic contains a description of the various screening models.

8.1.5.1 Kavetsky Single Deck Screen Model (230)

Kavetsky Model This topic contains a description of the Kavetsky Single Deck Screen model.

8.1.5.1.1 Model Description

Mechanistically a screening process can be regarded as a series of trials, as a

result of which particles of a particular size have a probability of entering the

fine product. This concept of defining the screening efficiency in terms of a

number of trials (or bounces) is the basis for a screen model.

A typical efficiency curve for a vibrating screen is shown in the figure below.

There are three regions on the curve:

A Typical Efficiency Curve for a Vibrating Screen

the region describing the above-aperture size material (region A),



the region describing the below but near aperture size material in which the

probability of passing through the aperture is directly dependent on particle

size (region B),

the region describing the ultra-fines that adhere to the coarse particles (region

C).

Region B of the efficiency curve is the important region for modelling purposes,

and it can be described by the equation (Whiten and White 1977).

E(x) = exp[-TRN.fo.(1-x/d)k] (A3.1)

where E(x) is the fraction of particles in the feed of size x which enter the coarse

product, d is the screen aperture; fo the fraction open area, TRN is the efficiency

parameter and k is a minor parameter used for precise fitting purposes.

Typically, the value of k is about 2. The performance of the screen in region C

can only be determined experimentally since it will be dependent on local

conditions such as the moisture content of the ore which causes small particles

to adhere to large particles. For design purposes it is necessary to make a

reasonable assumption about the shape of the curve in region C and this

assumption is made by the design engineer based on knowledge of local

conditions.

The typical dependence of the efficiency parameter, TRN, which is analogous to

the number of trials, on the feed rate is shown in the figure below for different

materials used for the screen deck.

The dependence of the screen efficiency parameters on the feed rate for

rubber and steel decks

The explanation of the above figure is that when the feed rate to screens with

rubber decks is low the particles move independently, accumulate energy, take

large bounces and have little opportunity to pass through the screen aperture.

An increase in feed rate causes an increase in inter-particle collisions, reduction

in particle energy and bounce lengths, and an increase in number of trials.

Hence, the screen efficiency increases. A further increase in feed rate causes

more particle interference, a decrease in the number of trials due to particles not



reaching the screen surface, and a decrease in screening efficiency.

With steel screens, however, the coefficient of restitution is low and particles do

not accumulate energy. Particle bounces are small and high efficiencies occur at

low feed rates. As the feed rate increases the inter-particle interference increases

and this reduces the number of trials and the screening efficiency.

Model

Limitations

A better understanding is required of the relationship between particle shape,

aperture shape and screen efficiency, and also of screening performance in the

difficult area between dry and wet screening. The first is a problem of

optimization of existing screens, the second is a problem of plant operation.

8.1.5.1.2 Model Equations

Region B of the screen efficiency curve is described by equation A3.1 .

E(x) = exp (- TRN * P/T) (A3.2)

where

P = fo*((1-fs) (1 - x/d)2 + fs*(1 - x/d))T (A3.3)

and

fs = 1 - (W/L) (A3.4)

In region A

E(x) = 1.0 (A3.5)

In region C an adjustment is made using the submesh factor (SF). This

adjustment transfers some of the submesh material in the undersize stream to

the submesh fraction of the oversize stream, that is to account for the small

particles that adhere to the larger ones.

The important operating parameter is feed rate per unit screen width (FW)

and this function is approximated by several straight lines as shown in Figure

A3.2.

The number of trials TRN is related to operating parameters by a set of

regression equations of the following form.

Ln(TRN) = A + B * FW + U * P1 + V * P2 (A3.6)

FW < FW1

Ln(TRN) = C + D * FW + U * P1 + V * P2 (A3.7)

FW1 < FW < FW2

where

C = A + (B-D) * FW1 by continuity (A3.8)

and

Ln(TRN) = C + D * FW2 + U * P1 + V * P2 (A3.9)

FW > FW2

SF is also related to operating parameters by a regression equation

SF = E + F * PSF + G * TSF (A3.10)

Fines Factor The fines factor is used to describe the "piggyback" effect of fines on coarse

317 318



material.

The material coarser than the "fines critical size" is considered in terms of its

notional surface area.

and SF* Area is the t/h of fines which are carried into the oversize product.

Moisture

Behaviour

For damp ores, the behaviour of moisture can be very important. There are

sometimes several kinds of moisture. The only one of interest to this model is

in the fines, that is, fractions finer than the "Moisture Split Critical Size XM".

All of the feed moisture is assumed to be carried in material finer than this

size. It is then allocated across the coarse and fine products in proportion

with how the material finer than XM is allocated.

Scaling The model allows scaling of screen length by linear scaling of the number of

trials parameter, TRN.

Scaling of screen width is accomplished within the normal model structure as

FW is feed rate per unit width.

Aperture, fraction open area and slot shape are also included as normal

model parameters.



8.1.5.1.3 Single Deck Model Printout

8.1.5.1.4 Symbols

Symbol Meaning

xi

size of particles in the ith size fraction

E(x) fraction of particles in the feed of size x which enter the coarse

product

X1, X2 lower and upper screen sizes at fraction being considered

X3 a critical size - if required - close to screen aperture. However V

is usually zero

X4 sub-mesh screen size, i.e., the smallest sieve in the series

TRN efficiency parameter (number of bounces or trials)

fo fraction open area

T total area of screen

W width of apertures

L length of apertures

fs fraction slot = 1- (W/L)

d maximum size of particle than can pass through the screen, ie.



aperture size

FW solids feed rate/unit width of screen

P1 % of feed of size x such that X1 < x < X2

P2 % of feed < size X3

SF submesh factor

PSF % of feed < size X4

TSF tonnes/hour feed of size , X4

XF fines factor critical size

XM moisture split critical size

A Regression constant

B Regression constant

C Regression constant

D Regression constant

E Regression constant

F Regression constant

G Regression constant

U Regression constant

V Regression constant

8.1.5.1.5 Know n Restrictions

Accurate application of the screen model requires data from the screen to be

simulated for parameter fitting. For simulation of screens for which data are

not available, data for a similar screen type with similar feed may be used.

using data from operations with markedly different screens or feeds will not

provide useful results.

The same square root of two series of screen sizes should be used for both

fitting and simulation.

The regression equations of the screen model make it quite complex and more

difficult to handle than most JKSimMet models.

For most processing plants only the tonnage dependence is required. That is

the values of U and V can be left at zero. For wire mesh screens often equation

A3.5 is adequate on its own.

Where there are large variations in the fitted submesh factor (SF) try the

dependencies of equation A3.9 as detailed in Sub Mesh Factor Modelling.

However, a constant SF is often adequate.

In a situation where you really want to tune a screen and are prepared to

collect a lot of accurate data, contact JKTech for assistance with the parameter

and regression fitting.

8.1.5.1.6 Parameter Fitting the Screen Model

Parameter Menu



Ap Length

Ap Width

OA %

A int (TRN)

B*FW (TRN)

D*FW (TRN)

U*P1 (TRN)

U*P2 (TRN)

E int (FF)

F*PSF (FF)

G*PSF (FF)

XF

XM

The basic concept of a number of trials is quite simple. However, the extensive

correction factors and sectionalised curves make this quite a difficult model to

fit.

The model fitting program can process only one set of flowsheet data at a time.

However, one flowsheet may contain many measured sets of screen data.

Clearly, the flow rate and near size dependencies require several sets of data

to define the screen efficiency v feed rate curves .

To describe any particular set of screen data, only a number of trials TRN

(parameter 22) and a submesh factor SF (parameter 23) need to be found.

Good initial estimates for these parameters are 5 and 0.1 respectively.

However, both TRN and SF are calculated variables in this model. Therefore,

we need to fit them as regression parameter A (Ln TRN) and regression

parameter E with FW1 set to a larger value than any anticipated screen feed

rates per unit of width and with B, V, U, D, F and G all set to zero.

Master/Slave

Fitting

Master/Slave model fitting allows the secondary dependencies on the

parameter menu to be established when multiple sets of data are available.

Setting up Master /Slave fitting is detailed in section 5.6.5.

Parameter dependencies are discussed in A3.7.

However, fitting of multiple data sets is complex and assistance from JKTech

consultants is strongly recommended if you intend to tackle this aspect of the

fitting process.

Aperture Length

and Width

Where screen data do not provide precise aperture and wire dimensions, the

screen aperture can be fitted to the data.

Note that for slotted screens, effective aperture length depends on the shape of

the particle because the size data are measured using square mesh screens.

Selection of Feed

Size Parameters

X1 to X4

Screen performance can be affected by the feed size distribution. This is

usually a secondary dependence compared with feed rate. However the

model does allow it to be incorporated. X1 and X2 are the upper and lower

sizes of a critical size fraction (or fractions). If a particular range of sizes in

your feed data is highly variable use X1 and X2 to bracket it.

Set X3 to the screen aperture; or the average screen aperture, if you are going to

fit several screen mesh sizes.

Set X4 to say - 2 or 3 times the submesh top size. The finer part of a size

distribution has most of the surface area and will tend to dominate surface

318



carryover.

Traditional screen design techniques relate a different “fines factor” to half of

the screen aperture. You can use X3 set to half the screen aperture to

approximate this dependence if there are large variations in fines in the feed.

Similarly, a traditional approach would use a “near size” dependence of

aperture size to half aperture size and X1-X2 can be set to estimate this

dependence.

8.1.5.1.7 Regression Model Parameters

Trials versus

Feedrate

This is the important dependence.

Fit each of the data sets available. This will give you a set of TRN values at

each fitted feed rate. You may also have a set of fractions between P1 and P2

at each TRN value.

The next step is to plot up (TRN) versus feedrate. Any graphing package eg

MS Excel, can be used. Select FW1 and FW2 to let you describe the curve

accurately in three sections. An alternative method is to print out your graph

(with a full grid) and rule on several line sections to suit. Their slopes and

intercepts will provide B and A and D and C respectively.

A multiple linear regression program can also be used - if you are adept with

such programs. Most spreadsheet programs (eg. Lotus, MS Excel) have built-

in multiple linear regression functions).

Critical Size

Dependencies

If your Trials (TRN) versus feedrate data are erratic and your data are a good

fit (less than 2 stream SD with Whiten weights), then it is worth trying P1 and

P2 dependencies.

Use a multiple linear regression program to fit ln (TRN) against feedrate, P1

and P2 and divide into separate data sets using your estimates of FW1 and

FW2.

You can impose the continuity constraint by correcting equations 6 and 8

ln(TRN) values by equation 7.

If you have a constrained non-linear fitting program which can handle

multiple equations, you can fit FW1 and FW2 as well. However, you will

need lots of good data.

Submesh Factor

Modelling

This is the other important dependence. For many operations, SF is small and

more or less constant. However, for operations with damp ore, it can be

crucial to a good model.

Once again, plot your best fit SF values against the calculated PSF and TSF

values from the parameter screens and draw a linear regression line against

any one variable. Print out the graph with a fine grid for this slope (for G) and

the intercept E. points.

Running the

Screen Model

Input your estimated values back into the screen menu and import to each of

your data sets. Try a simulation and check agreement on product streams.

Expect to make errors in this procedure the first few times.

Master/Slave

Fitting

For up to 10 data sets, Master/Slave fitting provides an excellent way of

estimating these dependencies for good data. You can add secondary

dependencies one at a time to test for a significant reduction in the sum of

squares.



Hint : Only the undersize and a flowrate is needed for a full screen fit.

8.1.5.1.8 References

WHITEN, W.J. and WHITE, M.E., 1977. Modelling and simulation of high

tonnage crushing plants, XII International Mineral Processing Congress,

Brazil, Volume II, 148-158.

WHITEN, W.J., 1984. Models and control techniques for crushing plants,

Control 84, Mineral/Metallurgical Processing, (Editor, J A Herbst), Publishers

- AIME, New York, 217-225.

8.1.5.2 Double Deck Screen Models (215 & 235)

The Double Deck Screen models (215 & 235) are simply two consecutive

applications of the Single Deck Screen models. Model 215 consists of

consecutive applications of the Simple Efficiency Curve Model (210) while

model 235 consists of consecutive applications of the Kavetsky Single Deck

Screen Model (230). The operation of the Kavetsky Single Deck Screen Model

is described fully in the previous topic.

8.1.6 Eff. Curves (210, 211, 212, 213, 203 & 240)

Efficiency

Curves

These models (210, 211, 203) use simple efficiency curves to describe the

operation of any classification device. For the filter model (240), the user

simply sets the U/F pulp density and the model redirects all the remaining

water out in the effluent stream.

8.1.6.1 Simple Efficiency Curve (210, 212)

Simple

Efficiency Curve

This topic contains a description of the Simple Efficiency Curve model.

8.1.6.1.1 Model_Description

The model is simply an efficiency curve with a fixed d50c and a fixed water

split to fine product. Refer to the figures in the Hydrocyclone model

description for efficiency curve shapes. A typical DSM screen has an

value of 4 and a value of zero.

The model can be used to approximate many classifiers. Therefore the default

parameter values should be used with caution.


Efficiency Curve

Relationship


Eo.(d/d

50c) =

C.(1+( . *d/d50c

)) (exp( ) - 1) / (exp( . *.d/d50c

) + exp( ) - 2)

When is 0, * is 1 and the above equation reduces to:

298



Eo.(d/d50c) = C.(exp( ) - 1) / (exp( .d/d

50c) + exp( ) - 2)


slope at larger values of d (d » d50c). Both and are normally constant for

given feed solids. The parameter * is determined, for given values of and ,

by the condition that:

Eo(1) = C/2

* is calculated iteratively in the model. C is the fractional water split to the

fine product.

Scaling This form of the model does not permit scaling.

8.1.6.1.3 Fitting the Simple Eff iciency Curve

Parameter Menu

This is a simple model to fit as it has no scaling capabilities. Fit the water

split, alpha and d50c. See the comments regarding fitting Beta in the cyclone

model description .

For DSM Screens, initial estimates of 4 for alpha and 50% for the water split

should be adequate for most data sets. An initial d50c estimate of half of the

actual screen aperture is appropriate

8.1.6.1.4 Simple Eff iciency Curve Printout

8.1.6.2 Simple Efficiency Curve - Water & Fines (211, 213)

Simple

Efficiency Curve

- Water & Fines

This topic contains a description of the Simple Efficiency Curve - Water &

Fines model.

8.1.6.2.1 Model Description

The model is also an efficiency curve with a fixed d50c as described above for

Model 210 with the added feature of allowing the fines and water splits to be

different.

306




Efficiency Curve

Relationship

The efficiency curve used in this model is the same as that described in A4.2.2

above except that C (fractional water split to fine product) is replaced in the

equations with a separate parameter F (fractional split of fines to fine

product):

Eo.(d/d

50c) = F(1+( . *.d/d

50c)) (exp() - 1) / (exp(*d/d

50c) + exp( ) - 2)


Eo.(d/d

50c) = F(exp( ) - 1) / (exp( .d/d

50c) + exp( ) - 2)

The shape parameter determines the initial rise, while a determines the

slope at larger values of d (d d50c

). Both and are normally constant for

given feed solids. The parameter * is determined, for given values of and , by

the condition that:

Eo.(1) = F/2

* is calculated iteratively in the model. F is the fractional fines split to the

fine product.

The water split is calculated directly from C, the fractional water split to fines

product.


8.1.6.2.3 Fitting the Simple Eff iciency - Water & Fines

Parameter Menu

This also is a simple model to fit as it has no scaling capabilities. Fit the water

split, the fines split, alpha and d50c. See the comments regarding fitting Beta

in the cyclone model description .306



8.1.6.2.4 Simple Eff iciency Curve (Model 211) Printout

8.1.6.3 Splined Efficiency Curve (Model 203)

Splined

Efficiency Curve

This topic contains a description of the Splined Efficiency Curve model.

8.1.6.3.1 Splined Eff iciency Curve (Model 203) Description

The model is also a simply an efficiency curve but the analytic form of the

curve used in Models 210 and 211 is replaced by a four knot spline curve.

8.1.6.3.2 Splined Eff iciency Curve (Model 203) Equations

Efficiency Curve

Relationship

The efficiency curve in this model is provided by specifying four pairs of

coordinates through which a smooth curve (piecewise cubic spline function)

is constructed. Fine end of the curve is specified by the water split as in Model

210.


8.1.6.3.3 Fitting the Splined Eff iciency Curve (203)

Parameter Menu

This also is a simple model to fit as it has no scaling capabilities. Fit the water

split and the four efficiency values at the knots on the spline curve. It is

important to remember to set the size values for the knots before attempting

model fitting.

Even though it seems incorrect, it is possible for the fitted efficiency values to

be greater than 1 or less than 0. Sometimes, model fitting arrives at values at

the ends of the curve which are outside the 0 – 1 range in order to achieve the

best shape for the curve inside the 0 – 1 range. This is due to the properties of



the spline curve for which the values at the ends of the curve have an effect on

the shape of the curve in the centre region.

The simulation model code truncates the efficiency values to be less than 1

and greater than 0.

The combination of these two features, control of the shape of the centre of the

curve and truncation at 0 and 1 ensures that the model predictions are

sensible.

8.1.6.3.4 Splined Eff iciency Curve (Model 203) Printout

8.1.6.3.5 Symbols for Splined Eff iciency Curve Model (203)

Symbol Meaning Equivalent JKSimMet

Parameter

Reduced efficiency curve

sharpness parameter.Alpha

Reduced efficiency curve dip

parameter.Beta

*Parameter for describing the

reduced efficiency curve.Beta*

C Water split to fines product. WS%Fines

F Fines split to fines product FI%Fines

d50c

Size of particle in the feed which

has equal probability of going to

fine or coarse product.

D50c

8.1.6.3.6 Know n Restrictions

Range of Validity The highly simplified form of these models means that extrapolation away

from the conditions at which the parameters were determined will

significantly decrease the accuracy. If a wide range of data is available, it may

be possible to use Model 251 which has a variable cut point.330



8.1.6.4 References

LYNCH, A. J., 1977, Mineral crushing and grinding circuits, (Elsevier,Amsterdam), pp 124-126.

8.1.7 Eff. Curve Variable D50c (Model 251)

Efficiency Curve

- Variable D50c

This chapter describes the Efficiency Curve Variable D50c model.

8.1.7.1 Model Description

This model is an extension of the Efficiency curve (Fixed D50c) model to

include a regression relationship for d50c. The water split to the fine product

remains fixed.

8.1.7.2 Model Equations

d50c

Relationship

For normal operation the classification size d50c

can be related to the operating

variables according to the equation:

Log10 (d50c

) = W * log10 (SW) + X * FW * C / 100 + Y * FPS + Z (A5.1

)

Efficiency Curve

Relationship


Eo.(d / d

50c) = 100.C.(1+( . *.d / d

50c)) (exp( ) - 1) /

(exp( . *.d/ d50c

) + exp( ) - 2)

(A5.2)


Eo.(d/d

50c) = 100.C.(exp( ) - 1) / (exp( .d / d

50c) + exp( ) - 2) (A5.3)


slope at larger values of d (d close to d50c

). Both and are normally constant

for given feed solids. The parameter * is determined, for given values of

and , by the condition that:

Eo.(1) = 100.C / 2

* is calculated iteratively in the model.




8.1.7.3 Efficiency - Variable d50c (Model 251) Printouts

8.1.7.4 Symbols

Symbol Meaning


reduced efficiency curve dip parameter


W,X,Y,Z regression constants in the d50c

equation

d50c

size of particle in the feed which has equal probability of going

to fine or coarse product

C % water split to fine product

SW slot width (mm)

FW volume flow rate of water in the feed (m3)

FPS % solids in the feed

8.1.7.5 Known Restrictions

As Model 251 is based on a regression equation, extrapolation beyond the

scope of the data used in the regression will decrease accuracy significantly.

Effect of the Log

Relationship

The relationship between d50c

and Slot Width is defined in Log space. This

means that the multiplier coefficient W will have a different effect for slot

widths less than and greater than 1.0 mm. For slot widths less than 1.0 mm a

multiplier greater than 1 will make the calculated d50c

value smaller than the

slot width. However, for slot widths greater than 1.0 mm, the effect is

reversed.This can cause unexpected results when changing slot width.

Screen Wear DSM screens are sensitive to wire wear condition. The screens are usually

reversed on a regular basis. If possible, test data should record the wear

condition. If this is not possible, test at both new and worn to obtain a range

of likely operation.



8.1.7.6 Fitting

Parameter Menu

W * Slot

X * FPS

Y * FdWater

Z (int)

Sharpness

Dip

C

This is a simple model to fit as it has no scaling capabilities. Fit the water

split, and d50c

. See the comments regarding fitting in the cyclone model

description (Appendix A2).

Initial estimates of 4 for a and 50% for the water split should be adequate for

most data sets.

An initial d50c

estimate of half of the actual screen aperture is appropriate.

Multiple Data

Sets

If the data cover a range of feed rates, feed percent solids, slot widths and

screen widths, proceed as follows:

Fit each data set for a, C and d50

.

Refit with average a and C set constant. That is, force all the variation into

the cut size.

Use Master/Slave fitting to fit the separation size equation (A5.1) for W, X,

Y and Z.

Note: If the slot width does not have a strong effect on d50c

, then the data are

very questionable.

8.1.7.7 References

LYNCH, A. J., 1977, Mineral crushing and grinding circuits, (Elsevier,Amsterdam), pp 124-126.

8.1.8 Simple Combiner Model (800)

Simple

Combiner Model

This topic contains a description of the Simple Combiner model.


Equipment The Simple Combiner model is available for selection for the Pump, Pump

Sump, Sump, Ball Mill, Tower Mill and Stockpile equipment. After opening the

Equipment window for the equipment, click on the Equipment model drop down

list to access the model options. Next click on the double arrow button to the

right of the drop down list to open the model window pertaining to the selected

model.

Model Overview For the Simple Combiner model, the mass in the particle classes of two or more

incoming feed streams is combined to produce the mass in the particle classes

in a single product stream of the combiner (Equation M800-1):



(M800-1)

The mass of water in the feed streams is also combined to produce the mass of

water in the Simple Combiner product stream.

Prerequisite

System PropertiesThere are no prerequisite system properties for this model for the Standard

input option, however the Volume output warning option requires the

Mineralogy system property to be added as a property in the particle class

definition table in Stream Specification.

Model Data Input The information required by JKSimMet to calculate the mass in a single product

stream using the Simple Combiner model is outlined below.

There are two options for the Simple Combiner model accessed via a drop

down menu on the screen:

1. Standard

2. Volume output warning

Standard Option The Standard model option requires no parameter input and has no prerequisite

stream properties, (see window below). The number of particle classes in all

feed and product streams is equal and the mass of a particular particle class is

conserved across the equipment unit.

Simple Combiner Model – Standard Option

Volume Output

Warning OptionThe Volume output warning option alerts the user when the flow rate of the

streams entering the combiner equipment exceed the volume capacity of the

equipment. When using this option, JKSimMet will report a warning to the

user at the completion of simulation when the Simple Combiner output flow

exceeds the Maximum Product Volume flow (m3/hr) specified.

The Volume output warning option for the Simple Combiner model is shown

below.



Simple Combiner Model – Example of Volume Output Warning Option

8.1.8.2 Symbols

Symbol Meaning

Mp

feed stream s mass in particle class p in an incoming feed stream, s, to the

combiner

Mp

product mass in particle class p in the single product stream of the

combiner


No relevant limitations.

8.1.8.4 References


8.1.9 2 Way Simple Splitter Model (810)

2 Way Simple

Splitter Model

This topic contains a description of the 2 Way Simple Splitter model.


Equipment The 2 Way Simple Splitter model is available for selection for the 2 Product

Splitter, Hydrocyclone, Flotation Cell, Flotation Column and Jameson Cell.

After opening the Equipment window for the equipment, click on the Equipment

model drop down list to access the model options. Next click on the double

arrow button to the right of the drop down list to open the model window

pertaining to the selected model.



Model Overview The feed to this model is split into two streams with size distributions, particle

classes and pulp densities identical to the feed. The controlling parameter is

the Fraction Split to Top Product. The top product is the upper product on the

equipment icon and is marked with a T. The parameter range is 0.0 to 1.0.

The 2 Way Simple Splitter model in JKSimMet combines the mass in the

particle classes of the feed stream and splits this mass according to a defined

ratio into the particle classes of its product streams.

A splitter is characterized by the fact that its combined feed composition is

equivalent to the composition of each individual product stream, that is, the

ratio of particle classes in the feed and product streams is equal, and the total

mass in a particular particle class is conserved across the unit.

Prerequisite

System PropertiesThis model can be used regardless of the properties that have been added as

properties in the particle class definition table in Stream Specification.

Model Data Input The information required by JKSimMet to calculate the mass in each particle

class in each of the product streams using the 2 Way Simple Splitter model,

and the models used to perform these calculations, are outlined below.

The user defines the fraction of the feed stream split to the top product, α.

Double click on the appropriate field to input the required value for Fraction split

to top product. This fraction is used during simulation to determine the mass in

each particle class in the product streams, Mp

product stream 1 or 2 (Equations M810-1

and M810-2).

This ratio is used in a similar manner to determine the mass of water in the two

product streams.

(M810-1)

(M810

-2)

The 2 Way Simple Splitter model is shown below.



Example of 2 Way Simple Splitter Model

8.1.9.2 Symbols

Symbol Meaning

Mp

feed stream s mass in each particle class in a feed stream s

Mp

product stream mass in each particle class in a product stream

α fraction of the feed stream split to the top product


This model makes no assumptions about the process used to separate. It is a

splitter only; the fraction split data must be entered by the user. There is no

relationship between feed or equipment unit conditions and the model output.

8.1.9.4 References


8.1.10 2 Way Volumetric Splitter Model (812)

2 Way

Volumetric

Splitter Model

This topic contains a description of the 2 Way Volumetric Splitter model.


Equipment

The 2 Way Volumetric Splitter model is available for selection for the 2 Product

Splitter, Flotation Cell, Flotation Column and Jameson Cell. After opening the

Equipment window for the equipment, click on the Equipment model drop down

list to access the model options. Next click on the double arrow button to the



right of the drop down list to open the model window pertaining to the selected

model.

Model Overview The feed to this model is split into two streams with size distributions and

particle classes identical to the feed. The controlling parameters are the

Fraction Split to Top Product (Water) and Fraction Split to Top Product

(Solids). The top product is the upper product on the equipment icon and is

marked with a T. The parameter range is 0.0 to 1.0.

The 2 Way Volumetric Splitter model in JKSimMet combines the volume in the

particle classes of any feed streams and splits this volume into the particle

classes of its product streams. Instead of entering a split ratio, in this model the

user defines the volumetric flow to the top product.

A splitter is characterized by the fact that its combined feed composition is

equivalent to the composition of each individual product stream, that is, the

ratio of particle classes in the feed and product streams is equal, and the total

mass in a particular particle class is conserved across the unit.

Prerequisite

System PropertiesThis model can only be used if the Mineralogy property has been added as a

property in the particle class definition table in Stream Specification.

Model Data Input The information required by JKSimMet to calculate the volume in each particle

class in each of the product streams using the 2 Way Volumetric Splitter model,


The user defines the volumetric flow rate to the top product. Double click on

the appropriate field to input the required flow rate for Volumetric flow rate to top

product (m3/h). This value is used during simulation to determine the volume in

each particle class in the product streams (see Equations M810-1 and M810-2

), where the split ratio, α, is equivalent to the defined top stream volume

flow divided by the stream volume flow in the combined feed streams. If the

defined top stream volume flow is greater than the combined feed stream

volume flow, JKSimMet sets the split ratio to 1.0.

This ratio is used in a similar manner to determine the mass of water in the two

product streams.

The 2 Way Volumetric Splitter model is shown below.

334



Example of 2 Way Volumetric Splitter Model

8.1.10.2 Symbols

Symbol Meaning

α split ratio, equivalent to the user defined top stream volume

flow divided by the stream volume flow in the combined

feed streams



splitter only; the volumetric flow rate to the top product must be entered by the

user. There is no relationship between feed or equipment unit conditions and

the model output.

8.1.10.4 References


8.1.11 Water & Solids 2-Way Simple Splitter (813)

Water and Solids

2-Way Simple

Splitter

This topic contains a description of the Water and Solids 2-Way Simple

Splitter model.


Equipmen

tThe Water and Solids 2 Way Simple Splitter model is available for selection for the

DSM screen, 2 Product Splitter, Rake Classifier, Spiral Classifier, Spiral Separator,

Hydrocyclone, Flotation Cell and Flotation Column. After opening the Equipment

window for the equipment, click on the Equipment model drop down list to access the



model options. Next click on the double arrow button to the right of the drop down list

to open the model window pertaining to the selected model.

Model

OverviewThis model is a variation on the 2-way simple splitter model. The feed to this model is

split into two streams with size distributions and particle classes identical to the feed

but the water in the feed is split in proportions different from the solids split to the two

products. The controlling parameters are the Fraction Split to Top Product (Solids) and

Fraction Split to top product (liquid). The top product is the upper product on the

equipment icon and is marked with a T. The parameter range is 0.0 to 1.0.

The water and solids 2 Way Simple Splitter model in JKSimMet combines the mass in

the particle classes of the feed stream and splits the solids mass according to a defined

ratio into the particle classes of its product streams and the liquid .. ratio.

Prerequisi

te System

Properties

This model can be used regardless of the properties that have been added as properties

in the particle class definition table in Stream Specification.

Model

Data

Input

The information required by JKSimMet to calculate the mass in each particle class in

each of the product streams using the water and solids 2 Way Simple Splitter model,


The user defines the fraction of the feed stream solids split to the top product, α and

the feed stream liquid to the top product β. Double click on the appropriate field to

input the required values for Fraction split to top product solids and liquid. These fractions

are used during simulation to determine the mass in each particle class in the product

streams, Mp

product stream 1 or 2 (Equations M813-1 and M813-2) and the mass of liquid in

the product streams.

The liquid ratio is used in a similar manner to determine the mass of water in the two

product streams.

(M8

13-

1)

(

M

8

1

3

-

2

)



The Water and Solids 2 Way Simple Splitter model is shown below.


8.1.11.2 Symbols

Symbol Meaning

Mps

feed stream s mass in each particle class in a feed stream s

Mps

product stream mass in each particle class in a product stream

α fraction of the feed stream split to the top product

Mpl

feed stream l liquid in feed stream s

Mpl

product stream liquid in product stream

ß fraction of the feed stream split to the top product





8.1.11.4 References


8.1.12 3 Way Simple Splitter Model (870)

3 Way Simple

Splitter Model

This topic contains a description of the 3 Way Simple Splitter model.




Equipment The 3 Way Simple Splitter model is available for selection for the 3 Product

Splitter equipment item. After opening the Equipment window for this item, click

on the Equipment model drop down list to access the model options. Next click

on the double arrow button to the right of the drop down list to open the model

window pertaining to the selected model.

Model Overview The feed to this model is split into three streams with size distributions, particle

classes and pulp densities identical to the feed. The controlling parameters are

the Fraction Split to Top Product and the Fraction Split to Bottom Product. The

top product is the upper product on the equipment icon and is marked with a

T. The parameter range is 0.0 to 1.0.

This model can be used regardless of the properties that have been added as

properties in the particle class definition table in Stream Specification.

Model Data Input The information required by JKSimMet to calculate the mass in each particle

class in each of the product streams using the 3 Way Simple Splitter model, and

the models used to perform these calculations, are outlined below.

The user defines the fraction of the feed stream split to the top product, αtop

, and

the fraction of the stream split to the bottom product, αbottom

. Double click on the

appropriate fields to input the required values for:

• Fraction split to top product

• Fraction split to bottom product.

On data input, JKSimMet calculates:

• Fraction split to middle product.

These fraction split ratios are used during simulation to determine the mass in

each particle class in the product streams (Equations M870-1, E870-2 and E870-

3).

The fraction split ratios are also used in a similar manner to determine the mass

of water in the three product streams.

(M870-1)

(M870-2)

(M870-

3)

The 3Way Simple Splitter model is shown below.




8.1.12.2 Symbols

Symbol Meaning

Mp

feed stream mass in each particle class in an incoming feed stream

Mp

product stream mass in each particle class in the product stream

αtop

fraction of the feed stream split to the top product

αbottom

fraction of the feed stream split to the bottom product





8.1.12.4 References


8.2 Comminution Models

This section describes the various comminution circuit models and contains:

a description of each comminution model available in JKSimMet

key equations forming the mathematical basis of the models

known limitations and restrictions

some guidance and restrictions for parameter fitting

Version 6.0.1 - March 2014 Comminution Models


typical model parameter values, where appropriate

There are a number of generic models included in JKSimMet that can be used

to describe the behaviour of a wide range of processes. For example, the

simple efficiency curve model can be used to describe any sort of classification

device, such as a cyclone or a spiral classifier. Selection and fitting of

parameters for these models will depend entirely on the type of process being

modelled.

Most of the process units available to the user when drawing the flowsheet

can be described by a number of models. Typically, a process unit will have a

specific model, developed for that particular device, and a number of generic

models. Selection of the appropriate model is at the user's discretion and will

often depend on available test data.

Note that all model parameters have default values and a permitted range.

The default value and range can be viewed by double clicking on the

parameter value. These values are not currently editable by the User.

8.2.1 Crusher Models (400 and 405)

Crusher Models This chapter describes the crusher models.

8.2.1.1 Model Description (Anderson/Awachie/Whiten)

The crusher model considers the crushing process as two components:

the selection of particles for breakage, and

the breakage of the particles so selected.

Selection Clearly, whether or not a particle is selected will depend principally upon its

size relative to the closed-side setting (CSS) of the crusher and the extent of

choke feeding. The size distribution of the daughter products of breakage will

depend principally upon the initial size of the particle and upon its physical

properties.

New feed entering the crusher is classified (or selected). Some material,

predominantly the finer fraction, bypasses the breakage process entirely and

reports directly to the product. The remainder is broken, and the daughter

fragments are then recycled to the classification step. The new fine fraction

exits via the product, and the coarser material is re-broken.

Perfect Mixing

Model

If we think of a crusher as a stage-wise breakage process, then we can model it

in terms of a steady state balance.

Version 6.0.1 - March 2014Comminution Models


Schematic Representation of the Crusher Model

A schematic representation of the crusher model is given in the above figure.

Mass balance equations may be written about each node as:

x = f + ACx (A6.1)

x = p + Cx (A6.2)

where x is a vector representing the amount in each size fraction in the crusher

f is the feed size distribution vector

p is the product size distribution

vector

C is the classification function, a

diagonal matrix describing the

proportion of particles in each size

interval entering the crushing zone

A is the appearance function, a lower

triangular matrix giving the

relative distribution of each size

fraction after breakage.

Combining (A6.1) and (A6.2) results in the Whiten crusher model equation:

p = ( I - C ) * ( I - AC ) -1 * f (A6.3)

where I is the unit matrix.

Since the feed and product are expressed as size distributions, and the

properties of the internal classification and breakage mechanisms are

expressed with respect to particle size intervals or mean sizes, it is convenient

to represent these quantities as vectors and matrices respectively.

Since f is known and p is the desired output, the problem resolves itself into

obtaining estimates of C and A for a particular machine and feed material.

These values can then be manipulated by simulation to explore the effects of

changing machine parameters, material characteristics or operating conditions

upon the product size distribution.

An important limiting factor in crusher operation is the power drawn by the

machine. This model permits estimates of power draw to be made for a given

condition, so that the simulations can be constrained by power requirements

(by the user). The power draw can be normalised to experimental data or

estimated from data for similar crushers in the Supplementary Parameters



Manual. Note: a single particle breakage test of the ore is required for either

type of power estimate.


p = (I - C) * (I - A * C)-1 * f

Selection Where C is the classification function (a diagonal matrix) and where C(x) is the

probability of selection for breakage of a particle of size x and is defined as:

C(x) = 1 (A6.4)

for x > K2

i.e. all particles are broken

C (x) = 1 - [ (K2-x)/(K

2-K

1) ] ^ K

3(A6.5)

for K1 < x < K

2

C(x) = 0 (A6.6)

for x < K1

i.e. no particles are broken

(x = mean particle size)

An example of the classification functions is given in figure A6.2.

Classification Function, c

The model equations are developed by non-linear regression analysis of

survey data collected over a wide range of operating conditions, followed by

multiple linear regression of the fitted parameters against the operating

conditions. The general form of these relationships is:

K1

= A0* Crusher gap - A

1 * Throughput + A

2* Feed coarseness

K2

= B0* Crusher gap - B

1 * Throughput + B

2* Feed coarseness

K3

= C0 (generally held constant at a value of 2.3)

First

Approximation

For many crusher types performance can be estimated by setting K1 to the

closed side setting, K2 to the open side setting (or K1 plus eccentric throw).

Both K1 and K2 will decrease with particle interference as the crusher

throughput increases to choke feeding.



The breakage severity (t10) will also increase (see A6.6 and equation A6.11).

The model allows for inclusion of minor variables where more detailed data

are available The equations in the model are of the form:

K1 = A

0* CSS + A

1 *TPH + A

2 * F80 + A

3 LLen + A

4(A6.7)

K2 = B0* CSS - B

1 * TPH + B

2 * F80 + B

3 * LHr + B

4 * ET + B

5(A6.8)

K3 = C

0 (usually 2.3) (A6.9)

Where:

CSS Closed side setting

LLen Liner Length

ET Eccentric Throw

LHr Liner Hours

TPH Crusher Feed Rate

F80 Crusher Feed 80% passing size

P80 Crusher Product 80% passing size

Note that only closed side setting and crusher throw will normally be used.

The other relationships require a very detailed experimental database.

8.2.1.3 Ore Breakage Characterisation

Andersen

Breakage Model

The Andersen model uses the results of JK breakage testing of coarse particles

to predict both breakage and crusher power consumption. This model has

been extensively tested on cone crushers (mostly operating as secondary

crushers) over a broad range of ore types. When the model was developed,

only the pendulum device was available for single particle breakage tests.

However, the JK Drop Weight test is now used as it provides for a wider range

of energies and particle sizes.

The first step is to use the JK breakage test to characterise ore breakage over a

range of input and absorbed energies. The absorbed energy (per unit mass of

particle) is referred to as the specific comminution energy.

8.2.1.4 Breakage Distribution Parameter

A typical size distribution of product from the JK breakage tester is given in the

figure below. This product size distribution may be adequately described by a

one parameter (t) family of curves (Awachie (1983); Narayanan and Whiten

(1983)). The parameter t10 is defined as the cumulative percent passing one tenth

of the geometric mean size, Y, of the test particle. The parameter is shown in the

figure below, together with other tn values - t2 and t4,- which are defined in a

similar manner to t10. Using the tn values (n= 10, 2, 4, 25, 50 and 75), the whole

of the size distribution may be fully described.



Typical pendulum product size distribution

The tn values (n = 10, 2, 4, 25, 50 and 75) for the product size distributions for

nine pendulum tests on hard rock ores from four major crushing operations at

different sites were determined and a 'best-fit' spline curve was drawn through

all of the tn data using a JKMRC multiple spline regression package, MSR. This

breakage distribution information may be conveniently stored as a three

dimensional spline relationship between the breakage distribution parameter,

t10 ( a measure of the amount of breakage or reduction), the cumulative percent

passing a particular relative size, and the relative size, tn, of the particle being

broken. Using the t10 spline knots 10.0, 20.0 and 30.0, Table A.6.1 gives the

cumulative percent passing the relative sizes t75, t50, t25, t4, and t2 i.e. the

cumulative percent passing the Y/75 size (etc), where Y is the size of the original

particle being broken as shown in Figure A6.4. The distribution for any

intermediate value of t10 is determined by spline interpolation.

SIZE RELATIVE TO INITIAL SIZE

T75 T50 T25 T4 T2

Breakage

Parameter t10

Cumulative Percent Passing

10.0 2.8 4.0 5.5 22.2 51.4

20.0 5.6 7.2 10.7 43.4 80.8

30.0 8.9 11.3 16.4 60.7 93.0

Appearance Function Data



The relationship between t10 and the remainder

of the product size distribution

8.2.1.5 Breakage Parameters

Breakage parameters can be established from regression analysis of the same

data as the classification equations.

t10 = D0* Crusher Gap + D

1* Throughput – D

2* Feed Size (F80) + D

3(A6.10

)

This equation shows the intuitively expected dependence on the crusher gap,

throughput and feed size distribution.

The "feed coarseness" factor is somewhat application dependent. That is, it

will be influenced by crusher liner profile and effective slope as well as closed

side setting and gap.

First

Approximation

Typical cone crusher operation for secondary and tertiary crushers will be at a

t10 of 15 to 20. For a lightly loaded crusher (size control on a primary jaw

crusher) will operate at a t10 of 5-10. A high reduction crusher (toothed roll or

choke fed tertiary) may achieve a t10 up to 25.

8.2.1.6 Crusher Power Predictions

Energy - Size

Reduction

Relationship

The JK breakage test also provides important information on the specific

comminution energy (kWh/t) required for a fixed size reduction, quantified by

the breakage distribution parameter t10, for each particle size broken.

The specific comminution energy, Ecs, defined as the amount of energy

available for breakage, is derived as the energy absorbed from the drop weight

on impact. This energy has been found to have a linear relationship with the

breakage distribution parameter, t10, but is also dependent on the test particle

size. This relationship is ore-specific and is used to characterise ores and

compare the crushing energy requirements of different ores.

Figure A6.5 shows the energy - size - size reduction relationship derived from

a JK breakage test for a fine-grained, siliceous copper ore.



Energy size reduction relationship

This information as used in the crusher model program in the spline form is

tabulated below. The energy required for a given reduction increases with a

decrease in particle size.

In Model 400, provision is made for data for three particle sizes. In Model 405,

the matrix is extended to accept data for five particle sizes to match the data

available from the JKTech Drop Weight Test.

Reduction

parameter

Particle size mm

t10 14.50 20.63 28.89

% Specific comminution energy kWh/t

10.0 0.35 0.30 0.25

20.0 0.80 0.70 0.50

30.0 1.2 1.0 0.80

Energy-Size Reduction Relationship (Spline Form) – Model 400

Reduction

parameter

Particle size mm

t10 14.50 20.63 28.89 41.10 57.80

% Specific comminution energy kWh/t

10.0 0.35 0.30 0.25 0.20 0.15

20.0 0.80 0.70 0.50 0.40 0.30

30.0 1.2 1.0 0.80 0.60 0.40



Energy-Size Reduction Relationship (Spline Form) – Model 405

Power Prediction

Method

A power prediction method has been developed using energy – size-reduction

information from the pendulum test (Andersen & NapierMunn, 1988) and is

also applicable to the Drop Weight test.

Using the ore-specific energy-size-reduction relationship from the pendulum

test, the breakage function, B the classification values Ci (from the parameter

fitting or model regression equations, the model calculates the total energy

required to reduce the feed size distribution to the product size distribution as

if all the feed was broken in the pendulum or drop weight testing device, i.e. it

defines the energy which would have been used by the breakage device to

achieve the same degree of breakage observed in the crusher. The sum of the

products of the amount of material selected for breakage in each size fraction,

Ci*xi (tonnes) (from equation (A6.3)), and the Ecs (kWh/t) for each size at the

breakage parameter value t10 (determined from the parameter fitting or model

regression equation (A6.11)), is the total comminution energy calculated by the

model, Pcalc (kWh).

This total model-calculated energy is then regressed against the actual power

draw observed during the plant surveys on a particular crusher using multiple

linear regression analysis, resulting in a simple equation of the form given

below.

Pobs = E1 * Pcalc + E

2(A6.11)

where Pobs is the observed crusher power draw (kW)

Pcalc is the model calculated comminution energy(kWh)

E1

is a constant dependent on the efficiency of the crusher

E2

is a constant of similar value to the 'no-load' power draw

The constant included in the regression equation adequately accounts for the

crusher machine power draw (the power required to overcome machine

frictional losses), or 'no-load' power draw as it is commonly termed. This 'no-

load' power appears to vary slightly with throughput and is a function of both

plant power factor and drive motor efficiency.

Feed rate (t/h) and feed coarseness are usually less significant variables and a

satisfactory model can be obtained by absorbing these effects into the constant

term. These variables are implicitly included in the pendulum power

calculation.

The power regressions developed may be used to predict the power

requirements of crushers operating on different ores after determining the

relationship between the breakage parameter, t10, test particle size, and the

specific comminution energy, Ecs, for the ore under investigation. The

pendulum test should be conducted on representative ore particles over the

range of the crusher feed size. Where a specific mathematical performance

model of the form of equations A6.7 to A6.10 has been developed from

extensive plant surveys, the power draw may then be predicted for different

operating conditions.

In a design situation, given the feed and the desired product size distributions,

the t10-size-Ecs relationship for the ore to be processed must be obtained from

the pendulum test and this information used in the model to calculate the total

comminution energy required. The crushing power requirements can then be



determined for a similar crusher from a power regression of the form of

equation A6.11 obtained from another site.

8.2.1.7 Crusher Model (400/405) Printout

8.2.1.8 Symbols

Symbol Meaning



f feed size distribution (vector)

p product size distribution (vector)

A appearance function (matrix)

C classification function (diagonal matrix)

I unit matrix

K1

size below which C = O

K2

size above which C = 1

K3

exponent in the equation for C

CSS closed side setting (mm)

TPH tonnes/hour feed

F80 coarseness of feed, e.g. 80% - 25.4mm

t10

breakage distribution factor

Pcalc total power consumed in size reduction using the pendulum (from

laboratory tests results)

Ai regression constant

Bi regression constant

Ci regression constant

Di regression constant

Ei regression constant


This is the most general of the crusher models developed at the JKMRC. It has

been extensively tested for large (7ft) cone crushers. The model provides an

excellent description for individual results for many types of crusher, e.g., jaw,

roll, toothed roll, hammer mill etc., but has not been extensively tested on these

other crusher types.

The feed coarseness relationships are usually based on scalped feed oversize

variations. They could well be different from variations in scalping screen

aperture. This interaction is a subject for continuing investigation.

For power calculations large particles are apparently softer (see Table A6.2).

The drop weight test is not suitable for particles of diameter larger than 63mm.

Hence, using specific comminution energies derived on smaller particles will

tend to overestimate required pendulum power.

There is also a physical flow limit for most types of crushers. For crushers

which cause a considerable increase in volume, this limit is important. Hence

for cone or 'Gyra disk' types, check the simulated flowrates against the design

tables for that type of crusher and the corresponding bowl and mantle.

Typical flowrates are available from standard references such as Mular and

Bhappu (1978), Chapter 11.

8.2.1.10 Fitting the Crusher Model

The model fitting subsystem only analyses one data set at a time. Hence the

actual parameters adjusted are the constant terms in each of the equations



A6.7, A6.8, A6.9 and A6.10.

That is, A4

for K1

B5

for K2

and D3

for t10

Parameter

Menu

There are two distinct levels of use of the crusher model. The different uses

require different fitting strategies.

Limited Data One data set allows a (somewhat approximate) estimate of product size for

small variations in closed side setting.

For one data set:

fit A4 and B

5

with A0 = 1.0, and B

0 = 2.0 and (for cone crushers) K

3 = 2.3.

Set other A and B values to zero.

Similarly for the breakage function:

fit D3

D0, D1 and D2 are set to zero.

Note that one data set does not provide useful information about power

dependencies.

Extensive Data The model is much more useful with a range of data. This means 5 to 10 data

sets covering a range of crusher settings, feed rates and (if possible) feed sizes.

JKTech can undertake breakage tests to characterize an ore as shown in Figure

A6.3 and Table A6.1 and to determine the size single particle breakage/power

as shown in Figure A6.5 and Table A6.2.



HP Grinding

Rolls

(and Others)

Note that the value of K3 is generally 2.3 for cone, jaw and gyratory crushers

only. For other types of crushers, such as grinding rolls and hammer mills, it

is advisable to fit K3 also, with 2.3 as a good initial estimate

8.2.1.11 Regression Modelling

The procedure is very similar to that for the screen model. Hence, an efficient

test program can be designed to gather screen and crusher data together.

Fit each test using only constant terms, A1, with all of the other regression

terms set to zero.

Use the ore Specific Appearance and Power Data measured by JKTech, or use

the defaults (average of 4 ore types). Measured oretype data should give more

accurate results for breakage and are essential for realistic power estimates.

Each data set produces estimates of K1, K

2, K

3 and A and B.

Set K3 = 2.3

Use a multiple linear regression package to fit each estimate to the measured

variables. If any coefficients plus or minus their estimated errors bracket zero,

try a refit without that variable included. If the error of prediction improves

(i.e., gets smaller), omit the variable by setting its model coefficient to zero.

8.2.1.12 Model Testing

Import each feed and product into the model and simulate to check each set.

This is quite a complex model and it is not difficult to make errors.

If any data sets are seriously in error, try to track down the reason. Check the

calculated K1, K2, and t10 against your fitted estimates. When all else fails (or

much earlier, if you prefer), ask JKTech, who will be happy to assist.

As soon as you have reasonable parameter estimates, you may use Master/

Slave fitting on up to ten data sets at a time to test secondary crusher model

dependencies.

8.2.1.13 References

ANDERSEN, J. A., 1989. M.Sc. Thesis, University of Queensland,

(unpublished).

ANDERSEN, J.A. and NAPIER-MUNN, T.J., 1988. Power prediction for cone

crushers, Mill Operators' Conference, Cobar.

AWACHIE, S.F.A., 1983, Development of crusher models using laboratory

breakage data, PhD Thesis, University of Queensland.

MULAR A. L. & BHAPPU, R. B. 1978, Mineral Processing Plant Design.

WHITEN, W.J., 1984, Models and control techniques for crushing plants,

Control 84, Minl./ Metall.Process (Am.Inst.Min.Engrs. Annual Meet.,

Los Angeles, USA, February), 217-225.

8.2.2 Rod Mill Model (410)

Rod Mill Model This chapter describes the workings of the Rod Mill model.




The rod mill model is based on the concept of stages of breakage. A stage of

breakage has three components:

selection

appearance

classification.

That is, each stage is equivalent to breakage, screening and recirculation.

The mill is considered as a number of segments in order. Each segment is a

stage of breakage.


Diagrammatically a stage of breakage may be considered as:

A representation of the breakage process in a rod mill

Eliminating m and q by matrix algebra yields

pj = (I-C) . (A.S +I-S) . [I-C(AS+I-S)]-1 . fj

or

pj = X . fj

since AS and C are assumed constant for all stages.

Stages of

Breakage

If there are v stages of breakage in the mill then:



p = (X) v f (A7.1)

or

p = XXX ... f for v times

Non-integer numbers of stages can only be calculated by interpolation.

Once A, S and C are known, any particular operating condition can be

represented by a value of v.

Feed Rate The key dependence is the variation of stages of breakage v with mill feed

rate F.

Experimentally:

F (v)1.5 = MC

where MC is the mill constant.

The mill constant can also be scaled as detailed later.

Appearance

Function

The default Appearance Function is the modified Rosin-Rammler equation:

A(x,y) = (1-e-x/y)/(1-e-1)

Where A(x,y) is the proportion after breakage of particles of initial size y

which are smaller than size x. The appearance A is made up of vectors of the

differences in x for the specified screen interval. For specific ores, JKTech can

measure the appearance function. A range of appearance functions for

various ores is given with the ball mill model description in Appendix A8.

Classification

Function

The classification function C is a diagonal matrix which provides a simple

classifier. Each diagonal element gives the proportion of that size fraction

returned to the breakage stage for rebreakage.

The usual values are (for a v2 size distribution)

1.0, 0.5, 0.25, 0.125, 0.063 and so on.

Hence, each stage of breakage in a rod mill will eliminate the top size fraction

from the product.

Selection Function The selection function, S is a diagonal matrix. It gives the proportions of

each size fractions which are selected for breakage.

S is represented by three parameters XC, SL and IN as shown in the figure

below, and is calculated by:

Si = SL * Size + IN for Size i > XC

Si = SL * XC + IN for Size i < XC

and limited if Si > 1.0 then Si = 1.0

and if Si < 0.0 then Si = 0.0

An example of a selection function is given in the figure below.



Graph of a rod mill selection function

Scaling The rod mill model is scaled by modifying the mill constant according to

dimensions and operating conditions described below:

Mill Size FACTA = (DSIM

/DFIT

)2.5 * LSIM

/LFIT

These scale factors only apply for rod mills with normal length to diameter

ratios, that is, 1.2 < simulated L/D < 1.6 and L 7m.

Media Load Load Fraction (i.e. volume of mill occupied by charge and media at rest after

grinding out)

FACTB = [(1 - LFSIM

) * LFSIM

] / [(1 - LFFIT

) * LFFIT

]

Note 30% < LF < 45%

Critical Speed Fraction Critical Speed

FACTC = CSSIM

/CSFIT

Note 50% < CS < 80%

These factors are applied to the Mill Constant MC of the original mill to

estimate the mill constant of the simulated mill.

MCSIM

= MC * FACTA * FACTB * FACTC

The required number of stages of breakage is

VSIM

= (MCSIM

/FSIM

)2/3

Feed Size Coarseness of feed (90% passing size)

FACTD = ln (F90FIT

/F90SIM

) / lnv2

VSIM

= (MCSIM

/FRSIM

)2/3 + FACTD

Ore Hardness Work Index

FACTE = - 0.8 ln (WISIM

/WIFIT

)

FACTF = ln [(S(I)FIT

/(1-S(I)FIT

)] + FACTE



FACTG = exp (FACTF)

S(I)SIM

= [FACTG/(1+FACTG)]

8.2.2.3 Rod Mill Model Printout

Rod Mill Printout Showing Default Values

8.2.2.4 Symbols

Symbol Meaning

f feed size distribution (vector)

p product size distribution (vector)



A appearance function (step matrix)

C classification function (diagonal matrix)

S selection function (diagonal matrix)

Si element of selection function S from size i

v number of stages of breakage of original mill

vSIM v for simulated mill

F90FIT 90% passing size for fitted mill feed

F90SIM 90% passing size for simulated mill feed

MCSIM mill constant for simulated mill

MC mill constant for original or fitted mill

SL slope of selection function

IN intercept of selection function

XC Size below which selection function is constant

DSIM diameter of simulated mill

DFIT diameter of fitted mill

LSIM length of simulated mill

LFIT length of fitted mill

LFSIM load fraction of simulated mill

LFFIT load fraction of fitted mill

CSSIM fraction critical speed of simulated mill

CSFIT fraction critical speed of fitted mill

WISIM work index of ore for simulated mill

WIFIT work index of ore for fitted mill

Note: The fitted mill is the rod mill which provided the

experimental data.


Scaling Note the restrictions for scaling in the section on Model Equations.

Change in Feed

Pulp Density

The number of stages of breakage is calculated from the feed solids mass

flow. No account is taken of water in the feed. It is assumed that rod mills

operate at 75 to 85 percent solids in the feed.

Effect of Feed

Size

There is some doubt about the adjustment of number of stages of breakage

according to feed coarseness. Data from some operations exhibit an effect

while data from others do not. If the particles are large enough and strong

enough to resist a rod impact, the dependence is reasonable.

The scaling effect can be eliminated from open circuit operation by setting

F90FIT (parameter 16) equal to F90SIM (parameter 80).

Mill Speed This dependence is reasonable from 50-80% of critical speed at industrial

mill feed rates.



8.2.2.6 Fitting the Rod Mill Model

Parameter

Menu

Because the rod mill model is dependent on feed conditions, it is difficult to

fit in closed circuit until the parameters are very good estimates. Therefore,

mass balance a closed circuit rod mill first. Then fit the discharge using the

mass balanced feed rate and sizing. (Use Whiten SDs for the product size

distribution). If an ore specific breakage function is available, it should be

used. the mill constant (MC) and the three selection function parameters can

be fitted.

For fitting, set the simulated and original mill dimensions etc. to the same

values.

Check the experimental feed 90% passing size and input it. Use a measured

work index if available - an approximate one if not.

This model is fussy about initial estimates and some trial and error may be

needed. These guidelines will help for many cases.

If you are new to the rod mill model use the rod mill example in Chapter 3

and graph the output to get a feel for how XC, SL and IN interact and change

the shape of the product curve.

Set XC to about half of the top size of the mill feed and MC to 2000. Assume a

selection value of 0.1 at XC and 1.0 at the feed top size. Calculate slope and

intercept to suit. Try a simulation with these values. If the product

distribution is approximately the right shape, (plot as cumulative percent

passing both simulated and experimental products) fit the rod mill constant.

If the shape is very different, increase the assumed selection value for a

steeper product slope and proceed when the slope is similar.

If the fitting program finds a reasonable minimum, - that is, the mill constant

error is less than 20% - change the MC estimate to the new value and fit the

slope. If the sum of squares decreases, update the SL guess to the fitted value

and fit XC and IN also.

8.2.2.7 References

LYNCH, A.J., 1977. Mineral crushing and grinding circuits, (Elsevier,

Amsterdam), 51-60.

8.2.3 Perfect Mixing Ball Mill (Model 420)

Perfect Mixing

Ball Mill Model

A new feature introduced with Version 5.2 was the extension of the ball mill

model to include a grate discharge option. Ball mill power is now calculated

for both overflow and grate discharge options (using the Morrell Power

Model) and is displayable in an information block.




This model considers a ball mill as a perfectly mixed tank with contents

described by a vector size distribution s.

The product vector p is produced by a discharge rate di for each size fraction,

where D is a diagonal matrix of rates, that is:

p = D * s (A8.1)

Within the mill, two factors control breakage. The first is the rate of selection

of each size for breakage. The second is the way in which the selected

particles are broken (or appear) in the mill contents.

Selected = R * s

where R is a diagonal matrix of rates.

Appearance = A * s

where A is a triangular matrix of breakage (appearance) functions

(distributions).

At steady state, the mill feed minus the material selected for breakage plus the

material from breakage minus the material discharged must equal zero. This

can be written as:

f - R * s + A * R * s - D * s = 0 (A8.2)

Discharge Rates For overflow mills and most of the operational range of grate discharge mills,

the discharge elements can be approximated by:

Di = Di* 4 * v / (d2 * l) (A8.3)

where Di* is close to unity

v is the total volumetric mill feed rate

d and l are mill diameter and length

A typical discharge function is given in Figure A8.1.

Typical graph of mill discharge function

Breakage Rates Breakage rates tend to increase rapidly with particle size, with the increase

tapering off at the feed top size.



Typical graph of breakage rate factor

Appearance

Function

The appearance function A is ore dependent, and can be measured using the

drop-weight testing technique developed at the JKMRC. A table of

appearance functions for a variety of ore types and the associated operating

work indices is given in section A8.7. The standard Broadbent-Calcott

appearance function is also included.


Considering equation 8.1 as the elements of each vector and matrix yields:

fi - R

is

i + A R s - D = 0ij

j=1

i

j j isi

(

A

8.

4

)

and:

pi = D

is

i(A8.5)

Substituting for si yields:

fi - p

i +

A ijj=1

i

R

D

j

j

pj- p

i = 0 (A8.6)

where feed and product are related by R/D for a particular breakage function.

Equation A8.3 can be used to scale for feed rate and mill dimensions.

In general, the mill contents s is not known and it is not possible to separate

the R/D* ratio into its components. The R/D* function is represented

internally by a cubic spline function (that is, by a smooth curve). A number of

spline knots (generally between 2 and 4) on the 1n(R/D*) function are fitted.

Scaling Scaling of the ball mill model is achieved by modifying the fitted R/D*

function according to dimensions and operating conditions as described

below.

Mill Diameter The mill diameter d is scaled.



FACTA =

Note: This factor is in addition to a direct volume effect which is built into the

model.

Load Fraction The load fraction LF is the volume of mill occupied by charge and media at

rest when the load is ground out.

FACTB =FITFIT

SIMSIM

LF . )LF - (1

LF . )LF - (1

Fraction Critical

Speed

Fraction critical speed is scaled by:

FACTC =

55% < CS < 78%

Work Index The Work Index is scaled by:

FACTD = 0.8

Ball Size Scaling By assuming that the reduction mechanisms of impact and attrition occur in a

ball mill, the following relationships can be derived from theoretical

considerations.

Impact breakage Db3

Attrition breakage 1/Db

where Db = ball top size diameter.

Impact breakage is assumed to predominate above a certain size xm whilst

attrition is the main reduction mechanism at sizes below xm. The size xm is

assumed to be equivalent to that at which maximum breakage occurs. Size xm

can be related to ball diameter as follows:

xm

= K * Db2

where K is the maximum breakage rate factor.

The value of K has been found to be of the order of 4.4 E-04. K can be

calculated from the formula above if the value of xm is known. The graphing

facility within JKSimMet allows easy graphing of the breakage rates to

determine this value.

xm (fit) and xm (sim) are both calculated. The smaller of the two is denoted

xm (small) and the larger as xm (large) .

The above relationships are used to scale R/D* values at each spline knot to

account for ball size effects.

The scaling factor for ball size effects depends on the knot position size.

for knot position size < xm (small)



SIM

FIT

FIT

SIM

Db

Db

Db1

Db1

FACTE

for knot position size xm (large)

2

FIT

SIM

Db

Db FACTE

For knot positions between xm (small) and xm (large) linear interpolation is

used.

The effect of ball size is shown in the diagram below.

R/D* Relationship with Ball and Particle Size

Scaling

Calculation

These factors are applied to each fitted 1n (R/D*) knot as follows:

R/D*SIM

= R/D*FIT

• FACTA • FACTB • FACTC/FACTD • FACTE

Scaling Using

Breakage

Functions

Where characteristic breakage functions have been measured (i.e. pendulum

tested) for both ores, these breakage functions may be used to predict

performance. Note that it is not valid to scale this way from the default

breakage function.



8.2.3.3 Ball Mill Model Printout

Ball Mill Model Printout Showing Default Values

8.2.3.4 Symbols

Symbol Meaning

f feed size distribution vector

p product size distribution vector

s mill contents size distribution vector

A appearance function lower matrix

R breakage rate function diagonal matrix

D breakage discharge function diagonal matrix

D* normalised discharge function

R/D*SIM normalised R/D ratio for simulated mill

R/D*FIT normalised R/D ratio for fitted mill

dSIM diameter of simulated mill

dFIT diameter of fitted mill

LSIM length of simulated mill

v volume flow rate of feed

LFSIM load fraction of simulated mill

LFFIT load fraction of fitted mill

CSSIM fraction critical speed of simulated mill

CSFIT fraction critical speed of fitted mill

WISIM work index of ore for simulated mill

WIFIT work index of ore for fitted mill

Db ball diameter (top size)

DbSIM ball diameter for simulated mill (top size)

DbFIT ball diameter for fitted mill (top size)



K maximum breakage rate factor


Change in

Coarseness of

Feed

It is known that the coarse end of the R/D* function does vary with gross

changes in the amount of coarse material in the feed stream. As the amount of

coarse material in the feed is decreased, the relevant R/D* values increase.

This limitation is not considered significant for changes of less than plus or

minus 50% in the amount of coarse material in the feed.

Critical Speed

Range

The critical speed dependence is approximately valid for 55-78% of critical

speed and incorrect outside of that range.

Predicting Rates

at 'Missing Sizes'

If the ball mill model does not produce any of a coarse fraction (i.e. none in the

mill discharge) then the effective rate of grinding is 'infinite'. One way to

overcome this problem is to size the mill contents and expand to the perfect

mixing model used for the SAG mill model.

This is usually not experimentally convenient. Some more practical

approaches are to:

Test the mill at maximum tonnage with coarse feed. If there is any coarse

material in the discharge, the actual rates can be estimated.

Use a set of rates and knot values from the supplementary information for a

similar mill feed sizing and fit with Work Index alone the first time.

Transfer the coarse rate values from calc to exp, return the Work Index to its

original value and refit the two smaller rates. This procedure should give

reasonable answers with a coarser feed. Work is proceeding on improving

the ball mill model in this area.

High Mill

Viscosity or Pulp

Density

The perfect mixing mill model only takes account of pulp density variations

as variations in mill volume. Therefore, higher pulp density will always

predict higher grinding rates. In practice, the rates do improve until pulp

viscosity begins to interfere with ball action and rates decrease rapidly. This

onset is difficult to predict as it is highly ore type dependent. However,

effective mill operation of greater than 50% solids by volume is unlikely and

improbable at greater than 60% solids by volume.

Ball Size Scaling The ball size scaling relies on the R/D* function exhibiting a maximum. If

there is no maximum in the fitted R/D* function, increasing the ball size will

give optimistic results.

Wide Range Size

Data

The mill model assumes a constant breakage function for all size fractions.

This assumption simplifies the model but experimental evidence suggest

strongly that partial breakage increases in severity with decreasing size -

down to some limiting size. Therefore, if more than (say) twenty size fractions

are considered, an apparent minimum rate may be produced in the finer

ranges. This phenomenon is more likely to be an artefact of an incorrect

assumption than to have any physical significance. Research work continues

in this area.



8.2.3.6 Fitting the Perfect Mixing Ball Mill Model

Parameter

Menu

The ball mill model is well-behaved for model fitting. It can be fitted in closed

circuit with the cyclone model with generally better results than by fitting

each model to mass balanced data. Hence a good closed circuit fit will also

provide a good mass balance estimate of circulating load.

R/D* Spline

Knots

Use three knots for normal grinding conditions and four knots for a wider

than usual size range (such as SAG mill discharge or a very fine product).

Knot Positions To determine an appropriate set of knot positions divide the number of size

fractions covering the feed size distribution by the number of knots plus one.

This will give about equal log size spaces from both ends and between knots.

Knot Estimates Estimates for the function values at the knot positions are provided as ln(R/

D*) values. A simple ascending series provides a good first estimate, for

example:

0.5, 1.5, 2.5

Work Index,

Load Fraction

If you have several sets of data, use an operating Work Index for each

(calculated from mill feed rate, mill power, feed and product 80% passing

sizes). If the major variation is hardness only, then the average knots can be

used.

The calculated R/D* values are displayed on the unit data entry screen.

There should be a smooth increase with size. Sometimes the curve will have a

maximum at the coarse end. If there are any sudden changes or ups and

downs, try adjusting the knot positions.

There will often be a bump at a change in size measurement technique, such

as the transition from screen sizing to Cyclosizer sizing.

Systematic deviations can sometimes be removed by adjusting a knot towards

the largest deviation.

Graph

Cumulative

Simulated and

Experimental

Product

When nothing else works, plot the experimental feed and product on a coarse

scale (say 0-30%) percent retained against log size. If there are any large

discontinuities, check your data very carefully, and repeat your sampling if

possible.

Master/Slave

Fitting

The perfect mixing ball mill model is well suited to fitting of multiple data

sets. The ln(R/D*) knot values can be fitted simultaneously for a number of

surveys. Ensure that you use the same knot positions, and number of knots,

for each mill in your master/slave fitting test.

8.2.3.7 Table of Appearance Functions

This table shows ore-specific appearance function values determined from

single particle breakage tests using JK breakage testers – pendulum or drop-

weight.



Size

Interval

Ball milling circuits from which the samples were collected

Massiv

e

Sulphid

e

(Ni)

Massiv

e

Sulphid

e

Coarse

(Pb-Zn)

Porphy

ry Hard

(Cu)

Porphy

ry Soft

(Cu)

Massive

Sulphid

e Fine

(Pb-Zn)

1 0.0591 0.0505 0.08586 0.05220 0.1128

2 0.1052 0.0974 0.1248 0.09919 0.1490

3 0.1318 0.1276 0.1387 0.1288 0.1497

4 0.1295 0.1278 0.1278 0.1284 0.1250

5 0.1127 0.1128 0.1076 0.1129 0.09885

6 0.0927 0.09469 0.08722 0.09423 0.07866

7 0.07486 0.07810 0.06960 0.07727 0.06289

8 0.06082 0.06428 0.05540 0.06339 0.04943

9 0.05005 0.05316 0.04428 0.05239 0.03842

10 0.04166 0.04424 0.03574 0.04364 0.03003

11 0.03462 0.03666 0.02899 0.03623 0.02376

12 0.02723 0.02880 0.02278 0.02847 0.01865

13 0.02054 0.02171 0.01743 0.02146 0.01448

14 0.01537 0.01623 0.01325 0.01604 0.01120

15 0.01144 0.01207 0.01004 0.01192 0.00864

16 0.00849 0.00894 0.00758

1

0.00883 0.00664

Operating Work Index

12.8 9.0 13.6 12.2 15.9

Size

Interval

Ball milling circuits from which the samples were collected

Quartzit

e

Sulphide

Low

Grade

(Cu)

Porphy

ry Soft

USA

(Cu)

Massiv

e

Sulphid

e

(Cu, Pb,

Zn)

Massive

Sulphid

e

(Pb, Zn,

Cu)

Standar

d

Functio

n



1 0.09514 0.0501

3

0.1171 0.1081 0.193

2 0.1322 0.0970 0.1537 0.1442 0.157

3 0.1417 0.1273 0.1522 0.1472 0.126

4 0.1267 0.1276 0.1247 0.1253 0.101

5 0.1049 0.1128 0.09723 0.1006 0.082

6 0.08477 0.0948

1

0.07685 0.08050 0.066

7 0.06778 0.0783

2

0.06131 0.06444 0.053

8 0.05371 0.0645

1

0.04810 0.05076 0.043

9 0.04244 0.0533

6

0.03729 0.03958 0.035

10 0.03379 0.0443

8

0.02911 0.03103 0.028

11 0.02709 0.0367

7

0.02303 0.02459 0.022

12 0.02127 0.0288

8

0.01810 0.01929 0.018

13 0.01637 0.0217

7

0.01407 0.01496 0.015

14 0.01254 0.0162

8

0.01089 0.01155 0.012

15 0.009565 0.0121

1

0.00841

3

0.00888

8

0.010

16 0.007279 0.0089

68

0.00648

3

0.00682

5

0.008

Operating Work Index

14.1 10.2 14.1 13.5

8.2.3.8 References

LYNCH, A.J., 1977. Mineral crushing and grinding circuits, (Elsevier,

Amsterdam), 309-312.

WHITEN, W.J., 1976. Ball mill simulation using small calculators, Proc.

Australas. Inst. Min. Metall., 258, 47-53.

MORRELL, S. 1992. Ball size effects in ball mills. Chapter 2, End of project



report, AMIRA/JKMRC Project P9J. "Simulation and Automatic

Control of Mineral Treatment Processes".

8.2.4 SAG Mill (Model 430)

AG and SAG

Mill Models

This chapter contains a description of the AG and SAG Mill models.


The JKMRC has been involved in the development of a model of autogenous

and semi-autogenous grinding for many years. The first model to provide

useful predictions was the Leung model (Leung, 1987). It used ore-specific

breakage functions obtained off-line using a laboratory test procedure. It has

largely been superseded by the Variable Rates model( see Appendix 11).

However, because of its relative simplicity, the Leung model provides a good

introduction to SAG mill modelling.

Caution: The Leung model scales on volume. This is irrelevant for

optimisation but is important for scale up from pilot to full scale mills of more

than 8 to 9m in diameter.

The power model (Morrell, 1991) was added in 1992.

The Leung model has the general structure shown in Figure A9.1. The

appearance function has two components:

high energy corresponding to impact breakage, determined from the twin

pendulum single particle breakage apparatus, and

low energy corresponding to an abrasion mechanism, determined from

laboratory tumbling tests.

In both cases the functions are obtained off-line on representative samples of

ore and do not rely on being simultaneously back-fitted to operating data. The

energy levels at which the high energy appearance function is determined are

based on the mean energy in the mill, which is related to mill diameter.

Discharge rates are determined as the product of the rate at which the load is

presented to the grate, dmax, and the classification at the grate (which is

represented by a simple classification function). The model iterates to select a

value of dmax equal to the fraction of mill occupied by material of a size less

than the grate size, which in turn is assumed to be a simple power function of

feed rate expressed as a proportion of mill volume.

The model predicts product size distributions and mill loads from a known

feed size and tonnage for a given mill and feed ore. Ball charge is

incorporated through the assumption that balls are equivalent to mill load

particles of equal mass.

Average breakage rates are provided as defaults for both the autogenous and

SAG mill models. Note that these rates are different and are based on a

limited data set.

Usually, breakage rates will be model fitted to plant data.

Limitations /

Cautions

This model is a significant development of earlier models, and has been

shown to be successful in describing operating data on full scale autogenous



and SAG mills. Its scale-up capability is limited to mills up to 8 to 9m in

diameter from pilot mills of up to 2m. The dependency of the model

parameters on operating conditions such as mill speed, percent solids, grate

open area, liner characteristics and pulp rheology was not well established

when this model was developed. Most of these issues are addressed in the

Variable Rates model(A13)

The Leung model is based on data from mills operating at approximately 70%

of critical speed and 60-70% solids by weight in the feed.

Autogenous Mill Model Structure

8.2.4.2 Equations - Particle Breakage

Particle

Breakage

This description follows the structure shown in figure A9.1.

The model assumes that each size fraction experiences only one energy level

of breakage. (The reality will certainly be a distribution of energy levels).

High Energy

Breakage

The relationship between the amount of breakage and the input energy is

described by

t10

= A (l - e - b Ecs ) (A9.1)

where t10

is the percentage of the broken particle which will pass through a

screen of one tenth the size of the original particle, and Ecs is the energy

absorbed per unit mass during breakage measured in kWh/t.

A and b are the parameters which characterize this equation for a particular

ore. A is usually taken as 50. Parameter b is derived from a drop-weight

breakage test of closely sized ore particles. Required sample size varies



according to ore variability. However, as a guide, about 50 kg of 50 mm

material is needed.

Low Energy

Breakage

One or more 3 kg samples of 50 mm natural ore are tumbled for 10 minutes in

a small dry mill at 70% of critical speed. The products of each run are sized

and t10

is measured for each run.

Where 50mm material is not available, other sizes are used and adjusted

using a simple linear model.

The t10

data are fitted to

t10

= a0 + a1 * mean size + a2 * sample mass + a3 * time. (A9.2

)

The actual value of the abrasion parameter ta is one tenth (scale factor only)

of t10

:

based on top size of 50 mm, mass 3 kg and time 10 minutes.

Low Energy

Appearance

Function -

Abrasion

The size distributions produced by ores tested to date have a similar shape.

This shape can be scaled to the ta factor that is the percentage passing one

tenth of the original particle size.

A cubic spline function is used for smooth interpolation.

A 100mm particle is chosen as an example as particles of this size will

typically undergo abrasion rather than crushing breakage. Parameter ta is

taken as 1.0 to make the scaling obvious.

size (mm) % passing

t value scale* 100 100

t1.25 2.687*ta 80 2.687

t1.5 1.631*ta 67 1.631

t10 1.0*ta 10 1.0

t100 0.9372*ta 1 0.9372

t250 0.8070*ta 0.4 0.8070

t500 0.6365*ta 0.2 0.6365

The example shows that most of a 100 mm particle remains unbroken.

This value of t is assumed to be equal for all size fractions.

Breakage Energy As the charge provides the grinding media, the level of available energy is

related to the coarse fraction of the mill charge.

The average size of the top 20% of the charge is used as the highest energy

reference level.

S20

= (p100 * p98 * p96 ... p80) 1/11 (A9.3)

and the potential energy at the full height of the mill

E1 = 4/3 . . (S20

)3 g D (A9.4)



where D is mill diameter in metres. An assumption due to Austin et al (1984)

is used to relate other energy levels to E1. Austin et al provided a rationale for

energy levels in mills to be related by

E particle 1/(x)1.5 (A9.5)

where x is particle diameter.

Hence, the energies experienced by smaller sizes are scaled using this

relationship. This allows an Ecs to be calculated for each size and t

calculated from equation (A9.1).

High Energy

Appearance

Function

(Crushing

Breakage)

Once the energy of breakage is known, the distribution the particle breaks

into can be described by a cubic spline surface.

spline knots t = 0.0 10.0 30.0 50.0

function values for

t2 0.0 50.53 92.49 96.47

t4 0.0 23.33 61.58 82.86

t10 0.0 10.00 30.00 50.00

t25 0.0 4.975 15.62 25.88

t50 0.0 3.064 9.412 14.71

t75 0.0 2.325 6.893 10.32

For example, for a 50 mm particle, a t of 30 would produce this distribution.

% passing Size (mm)

50 100

t2 25 92.49

t4 12.5 61.58

t10 5 30.00

t25 2 15.62

t50 1 9.412

t75 0.67 6.893

Combined

Appearance

Function

As noted earlier, the abrasion distribution does not vary with particle size

while the crushing breakage is highly dependent on particle size.

Hence, abrasion will tend to dominate for coarse particles and impact for

fine particles (from equation (A9.5)).

To generate an appearance function for each size fraction, the high and low

energy appearance functions are combined proportionally.

a = (tLE * aLE + tHE * aHE) / (tLE + tHE) (A9.6)



where

aLE and aHE = low and high energy appearance functions,

tLE and tHE = low and high energy t values

Equations (A9.1) to (A9.6) combined with the two tables of spline knots

yield a complete appearance function (that is how each component will

break) for each size in the mill load.

Breakage

Rates

To predict a product from the mill contents and the appearance function

requires only a rate of selection for breakage for each size fraction of the mill

load.

These rates will be inherently scaled because the mill load will be

constrained by mill dimensions and the mill diameter (if the energy versus

breakage assumptions are correct). These rates will certainly vary if mill

speed is changed but this dependence is not included in the Leung model.

To describe these rates, a five knot spline function is used.

Best fit values to data are tabulated.

Spline knots (mm) ln (Rate of

Breakage)

Autogenous

ln (Rate of

Breakage)

SAG

0.250 2.63 2.176

4.00 4.04 4.444

16.0 3.32 3.577

44.8 1.98 2.753

128 3.37 4.082

These are the default values in each model.

These rates are fitted to customize the model to any particular operating

mill.

SAG Mill

Modification

The ball charge is approximated by a distribution of equivalent weight

particles added to the mill load for the high energy breakage calculation

(equation (A9.3)). That is, only the appearance function will be varied by

the addition of balls.

This completes the description of the Breakage area of the model.

8.2.4.3 Equations - Mass Transfer and Discharge

Classification The mill grate is modelled as a very simple classifier. When this model was

developed the relationship between the classification, discharge and the

operating conditions was not well defined. Hence, the classifier/discharge is

assumed to be constant- for other than minus grate size hold up. A simple

form is used.

D = 1 x < xm

(A9.7)

D = [ ln(x) - ln(xg) ] / [ ln(x

m) - ln(x

g) ] x

g > x > x

m



where xm

is the particle size below which it will always pass through the

grate if presented to it - that is, behave like water. xg

is the size of the grate

through which the largest particles will pass through.

Pebble Port

Modification

Pebble port allows a small discharge rate of substantially coarser particles.

This modification affects the classification curve as shown below.

Pebble Port Effect on Classification Curve

xp is the notional size of the pebble port

fp

is the notional fraction open area of the pebble ports compared with the

fraction of grate open area.

Typical values for fp are 2 to 5% ie. 0.02 - 0.05. While this modification gives a

good description of pebble product, the areas are notional only and in fact

reflect relative discharge rates.

Discharge Rate The quantity of pulp discharged will depend on the quantity per unit time

presented to the grate multiplied by the classification function.

d = dmax

* D

where dmax

is the fraction of the load presented to the grate per unit time and

D is the classification function.

The water is assumed to follow the sub mesh particles.

The actual value of D is found iteratively.

The required value satisfies the following empirical mass transfer law

(Austin, 1976).

Mass Transfer

"Law"

The value of dmax is adjusted until the model prediction matches the required

one. That is, until it lies on the operating line of

L = m1 Fm2 (A9.9)

where

m1 = 0.37

m2 = 0.37

L is the fraction of the active volume of the mill occupied by minus grate size

material and F is the total volumetric feed rate per minute divided by the



active volume of the mill.

Perfect Mixing

Mill Model

The perfect mixing model at steady state provides the structure to combine the

various components of the model. It relates the different parts in the following

manner.

fi - r

i s

i + - d

is

i = 0

(

A

9.

1

0)

pi = d

i * s

i(A9.11)

where fi, s

i, r

i, d

i and p

i are feed rate, contents, breakage rates, discharge rates

and product rate vectors and aij is the combined appearance function.

The form of equations (A9.10) and (A9.11) allows both the mill load and the

product to be calculated for any mill load and discharge rate adjusted until

equation (A9.9) is satisfied.

Calculation sequence:

1. Calculate breakage rates

2. Calculate volume of below grate size material in the mill, L

3. Calculate discharge rate

4. If error is acceptable exit else make correction to Dmax

Mill Load This model is unusual because it uses an internal port to describe the mill

contents. This port is accessible from the model properties drop down or from

the model window. It does not appear as stream equipment.

Scaling This model is inherently scaled for mill diameter and volume. This scaling

optimistic in capacity as mill diameter is increased. It is reasonable for mills of

up to 8 to 9 m diameter.

8.2.4.4 Prediction of AG/SAG Mill Power Draw

The Grinding

Mill Power

The gross power draw of the mill is that drawn by the mill motor(s), ie metered

power. It is assumed that this has two components, viz

net power, ie. the power delivered to the charge

no-load power, ie. the power to overcome drive train and bearing losses.

The gross power can, therefore, be represented by the following equation

Gross Power Draw = No-Load Power + Net Power (A9.12)

The gross power draw is calculated from the fraction critical speed, ball SG

and ball and rock porosity. These data are provided by the user. The

calculations use pulp load data generated by the model calculations.

The model data entry screen section for the power calculations include the

'net power adjustment factor'. This is a calibration constant which varies

slightly from mill to mill depending on mill liner configuration and other

factors.

Users are strongly recommended to leave this value set at 1.21. Other values



should not be used unless a comprehensive range of load vs power data are

available.

Net Power Draw From photographic evidence, the charge shapes shown in Figure A9.2 were

assumed to occur in grate discharge mills.

Simplified AG/SAG Mill Charge Shape

By considering an element in the charge of cross sectional area r ds d and

Len, the torque inertia of the element can be represented by the following

equation.

Torque Inertia of Element = g Len r2 cos d dr (A9.13)

Power can be defined in terms of torque ( ) and rotational rate (N) as follows:

Power = 2 N (A9.14)

For grate discharge mills, by integrating between the limits s

and T

and

between ri and r

m the net power (P

net) is given by:

.drd cos r gLen 2 = P 2

r

r

net

m

i

S

T

rN(A9.15)

No-Load Power The no-load power draw (i.e. that drawn by the mill when completely empty),

is associated with various electrical and mechanical energy losses. The main

ones are motor, gearing and bearing losses. None of these are fixed over the

full mill operating range. Some, however, may have a fixed component. For

example, bearing losses due to friction will be dictated by the mill's dead

weight (though even this will vary as liners and lifters wear), and the mill

charge weight which will clearly vary with grinding condition.

To determine the relationship between no-load power and mill design

parameters, data from pilot and industrial mills ranging from 1.7 to 7.2 m in

diameter were analysed. However, these no-load powers are difficult to

measure precisely. The problems are power factor effects at low loads and

achieving a completely empty mill. The parameter Diam3Len N was



regressed against no load power and found to provide a good fit (Figure A9.3).

The relationship developed was as follows with N converted to the fraction of

control speed:

No Load Power (kW) = 2.62 (Diam2.5 Len )0.804

Hence, this equation estimates the likely indicated no-load power for an

installed mill.

Indicated vs Fitted No-Load Power

Power

Calculation

Accuracy

The most recent JKMRC database currently includes power data from 63

different mills. Details are shown in Table A9.1.

Ball Mills SAG

Mills

AG Mills

Diameter (m) 0.85-5.34 1.80-9.59 1.8-9.50

Belly Length Inside Liners

(m)

1.52-8.84 0.59-7.95 0.59-5.18

Length/Diameter Ratio 1.00-1.83 0.33-1.50 0.33-1.0

Percent of Critical Speed (%) 60-83 48-89 72-75

Ball Filling (Vol %) 20-48 3-25 0

Total Filling (Vol %) 20-48 7-38 10-31

Specific Gravity of Ore 2.6-4.6 2.6-4.1 2.7-4.6

Number of Mills 38 20 5

Number of Data Sets 41 28 7

Power Draw (kW) 6.8-4100 14.8-7900 12.5-

5500



The power model has been applied to this database and was found to give

excellent results. The standard deviation of the relative error of the model was

calculated to be 6.5% for gross power..

The model therefore requires a knowledge only of mill dimensions and speed,

ball charge, volume occupied by balls and pulp, and the ore specific gravity.

Full details of the model are given in Morrell (1991).

Because of the industrial database, the prediction of gross power is the most

reliable.

Restrictions This power model assumes the SAG mill grate and pulp lifters do not limit

pulp throughput. For a large diameter mill (say > 7m) in closed circuit with

hydrocyclones or fine screens, this assumption may not be justified. A build

up of fine slurry in the mill will remove some of the charge imbalance and

reduce the actual power draw.



8.2.4.5 SAG Mill Printout

SAG Mill Printout



8.2.4.6 Symbols

Symbol Meaning

aij fraction of size j which breaks into size i

A Ecs model parameter

b Ecs model parameter

dmax discharge rate at xm

di discharge rate of size i

fi feed rate of size i

Ecs Energy absorbed per unit mass during breakage in each size

fraction

E1 particle potential energy at full height of mill

F volumetric feed rate/mill volume

HE High Energy

LE Low Energy

L mill volume fraction of minus grate size

m1, m2 mass transfer parameters

si mill contents of size i

rj rate of breakage out of size j

S20

average size of top 20% of mill load

t10 percentage which passes through a screen aperture of 10%

of the original size.

tp percentage which will pass through a screen of aperture

original size /p

ta abrasion parameter

xi particle size

xg grate size (mm)

xm size below which all will pass through the grate (mm)

g gravitational constant

charge density

r radial position of element

angular position of the element

Nr rotational rate at a radial distance r

rm mill radius

ri charge surface radius (see Figure A9.2)

s angular position of the shoulder



r angular position of the toe

Diam mill diameter (m)

Len mill length (m)

fraction of critical speed.


The model is not valid outside a range of 55% to 75% solids by weight in the

feed.

Mill speed is assumed to be 70% of critical or close to it. However for small

changes in speed (~ ± 5%) a good approximation can be made by multiplying

the rate at each knot by the relative change. That is, for +5% (ie. 70% increased

to 73.5% critical) multiply by 1.05 or add ln (1.05) to the logarithm of the knot

value. This assumes the number of impacts per mill revolution will not

change. In reality more speed will give more lift and a slightly higher

breakage energy.

The classification model is very simple and only dependent on grate size. The

xm parameter is driven by slurry viscosity. For viscous ores, xm may be up to

1mm. For clean ores (hard rock, clay free) 0.1-0.2mm is typical.

This model has been tested against a large number of full-scale operations

and a very wide range of pilot plant test data. The model has provided good

predictions for design (Morrison, Kojovic and Morrell 1989) over a wide range

of ore types.

Detailed comparison with pilot plant data has highlighted areas where the

model assumptions are not a sufficiently good approximation. Known areas

to treat with caution are as follows.

The assumption that grinding rates are constant at a given ball load is not

true when

there are large variations in mill feed sizing

the mill is taken from open circuit to closed circuit.

Operating Limits The model is numerically stable at any mill load (equation (A9.9)). Real world

mills typically operate with maximum loads of 30 to 35% by volume of charge.

However, they may be limited by motor power at much lower loads. There is

usually a limit on ball load of 5 to 10% because of mechanical or power

constraints.

It is the engineer's responsibility to check these parameters against the limits

for a particular mill.

Feed Sizing The auto/SAG model 'forms its load' from the mill feed. If the mill feed size

distribution is smooth (ie. a reasonably straight line on a Rosin-Rammler

plot), simulated variations in feed sizing give sensible results. If the coarse

end of the feed distribution is artificially adjusted for the feed is preclassified

in some way, then the S20 assumption that the load can be treated as a single

number becomes unjustified. Hence artificially adjusted top sizes will cause

the model to predict wide variations in performance.

(While these variations are excessive, it should be noted that real auto mills

are also sensitive to feed top size).



Similarly, if those fractions that limit throughput (notional critical size) are

prescreened from mill feed, the model will be optimistic about increased

throughput.

(Once again, real SAG mills will also achieve much higher throughputs).

However, predictions for recycle crusher are quite realistic.

If mill operation is closed with a fine classifier (DSM screen or hydrocyclones)

there is usually an increase in the observed grinding rates at 4mm. This

means a typical SAG mill may have some 'free' grinding capacity for particles

a few millimetres in diameter. Where the simulated mill is operating in closed

circuit with a screen, the circulating load will tend to vary more (and the mill

load less) with changes in hardness and feed sizing than the real mill.

However trends will be correct and overall product sizing should be close.

Mill Power Accurate measurements or estimates of mill dimensions, speed and ball and

pulp load are required for the power calculation. Ensure that all data used

are accurate.

Ball Size Effects Ball effect is estimated by generating an equivalent load of ore particles. As

the top 20% of this load is used to find S20, only the top one or two ball sizes

can have any 'impact' on this calculation. Manipulating the finer ball sizes

(ie. < half top size) have very little effect. In practice, it does change the fine

grinding rates.

Ball Load Effects These have been investigated in some detail at pilot scale. In general, the

harder the ore (low b and low ta) the less the grinding rates are affected. A

soft ore however follows the accepted wisdom that increasing ball load will

produce a coarser product. This may well be because the increased number of

balls are now breaking the ore particles in the load which were doing the fine

grinding.

Discharge Rates Considerable work has been carried out by Morrell (1990) on factors affecting

discharge rates. These effects are also summarised in Morrell and Morrison

(1989). See A11 for details.

Overall, discharge rates will only become a limiting effect in very high

viscosity ores. In this case, operation at a lower pulp density is recommended.

The SAG mill is an effective pump and the charge will remain relatively 'dry'.

Mill Liner Effects The SAG mill model is valid for correctly designed traditional 'high/low' lifter

type action. Wave liners or short lifters do not provide enough lift to achieve

the default rates. If poor lift is combined with poor discharge, the mill only

produces abrasion with a very fine product at a correspondingly low

throughput.

Further

Developments

The JKMRC now has a substantial database of SAG/auto mill surveys and

breakage characteristics. This data base has been used to develop the wider

range variable rates AG/SAG model described in Appendix 11

Mill Load Limits The autogenous and SAG mill model does not include an explicit maximum

for the mill load. However, a warning will be flagged if the total load (ie. balls

and pulp) exceeds 40% by volume. If the total load exceeds 60% by volume an

error will be flagged and the model calculations will be stopped.

8.2.4.8 Fitting the Autogenous & SAG Mill Models

XG



XM

Rate 1

Rate 2

Rate 3

Rate 4

Rate 5

Parameter Menu

These models are complex and calculation intensive. However, any

computer which is suitable for MS Windows 95/98/NT should be

adequate for AG/SAG model fitting.

In the unlikely event that the fit is slow, the Select list may be used to

restrict the scope of calculation or to fix recycle streams as “feed”

streams.

Initial Values Use the grate width and 100 µm as initial estimates for xg and x

m.

The default breakage rates for auto and SAG will provide a good guess

for each knot value.

Ore Type Parameters For accurate results, these are best derived from tests carried out on

representative samples at JKTech.

For an existing operation, the values provided in the volume of

supplementary information provide some guide to possible values.

Mill Load If a reasonable estimate of load mass and sizing is available, then fitting

with a range of A and b values may provide a way of estimating these

values - that is - use the values which give the best fit for ratio work.

Mill Load is fitted by inputting it as raw data into the dummy product

stream. If you only have a total mill load estimate (eg. from bearing

pressure), set the size fraction SDs to zero and the load SDs

appropriately. Subtract the weight of balls from this load for a SAG mill

and input it on the model screen.

Closed Circuit

Operation

If the mill is being operated in closed circuit with hydro-cyclones, it is

better to reduce m1 from 0.37 to 0.25. This seems to provide a better

approximation of the mass transfer response for a large recirculation of

material finer than grate size.

Knot Positions The spline knot positions are better left where they are for the 'normal'

range of SAG mill feed sizings, 80mm < F80 < 250mm. However for very

fine auto mill feeds, the limiting size fraction will also be finer and it may

help to scale down all the knots. That is, reduce them by the same ratio.

An alternative is to simply fix the larger knots at their default values.

Hint: If the closed circuit simulation gives a very different circulating

load, check carefully for size biases in the fit or in the data itself.

Master/Slave Fitting The Master/Slave fitting can be used with multiple sets of SAG/auto

data. Ensure that you are using the same knots positions for each mill in

the test. Similarly, each survey data set to be fitted simultaneously

should have been collected with the same grate and pebble port size, and

ball load.



8.2.4.9 References

AUSTIN, L.G., LUCKIE, P.T. and KLIMPEL, R.R., 1984. The process

engineering of size reduction: Ball Milling, S.M.E/A.I.M.E., NEW

YORK: 561pp.

AUSTIN, L.G., WEYMONT, N.P., PRISBREY, K.A. & HOOVER, M., 1976.

Preliminary results on the modelling of autogenous grinding. 14th Int.

A.P.C.O.M. Conf. The Penn. State Uni.: 207-226pp.

LEUNG, K., 1987. An energy based ore specific model for autogenous and

semi-autogenous grinding. Ph.D. Thesis, unpublished, University of

Queensland.

LEUNG, K., MORRISON, R.D. and WHITEN, W.J., 1987. An energy based ore

specific model for autogenous and semi-autogenous grinding. Copper

87. Chilean Institute of Mining Engineers, Santiago, Chile.

MORRELL, S. 1990. Simulation of bauxite grinding in a semi-autogenous mill

and DSM screen circuit. MEng Thesis, University of Queensland

(unpublished).

MORRELL, S. and MORRISON R.D. 1989. Ore charge, ball load and material

flow effects on an energy based SAG mill model. SAG Conference,

University of British Columbia, Vancouver.

MORRELL, S., NAPIER-MUNN, T.J. and ANDERSEN, J. 1992. The prediction

of power draw in comminution machines. Comminution-Theory and

Practice, K. Kawatra (ed), SME, Chapter 17, pp. 235-247, 1992.

8.2.5 Size Converter Model (490)

Size Converter

Model

This chapter contains a description of the Size Converter model.

8.2.5.1 Introduction

The model provides a product size distribution with a user specified P80. This

is achieved by adjusting the feed size distribution finer or coarser as required.

The model is useful when there is no process knowledge of upstream

comminution devices, or when a size distribution of a particular size is

required for sensitivity analysis.

8.2.5.2 Model Details

The feed to the model is adjusted by moving it sideways on a Cum % Passing

v size plot until the product P80 matches the specified P80 as closely as

possible.

8.2.5.3 Fitting the Size Converter

There are no fittable parameters in this model.




The model is limited in its ability to generate a product which is coarser than

the feed by the coarsest screen available in the feed combiner and product

ports. It is always wise to plot and inspect the graph of the feed and product

to ensure that the shape of the distribution is reasonable.

8.2.6 Variable Rates SAG Model (435)

Variable Rates

SAG Model

This chapter contains a description of the Variable Rates SAG model.


The Leung AG/SAG model (A9) typically requires a full scale plant or pilot

mill survey combined with ore breakage testing to generate a set of grinding

rates. However research in the mid 1990’s using a large database of pilot and

full scale milling tests has lead to the development of a correlation between

model grinding rates and mill operating conditions. A further correlation

between mill feed sizing and ore breakage characteristics has also been

developed. These two correlations now allow mill performance to be predicted

for a wide range of mill sizes and operating conditions. Hence the model can

be used to evaluate optimisation strategies in existing plants and to

investigate (and compare) grinding circuit configurations at the pre-feasibility

stage thus reducing the cost of pilot testing.

The underlying model is still identical with that developed by Leung et al

(1987) except that

grinding rates have been related to mill diameter and operating conditions,

and

A model that includes grate geometry (but does not incorporate pulp lifter

capacity) now describes slurry holdup.

This approach was reported by Morrell and Morrison, 1996.

If you are new to SAG mill modelling, it is strongly recommended that you

work through Appendix 9 (the Leung model) before attempting to use the

Variable Rates model.

The VR model interface has been slightly revised for Version 5 mostly to make

recycle effects easier to specify.

8.2.6.2 Scaling Approach

A large proportion of AG/SAG model users either carry out pilot scale tests

and wish to predict full scale operation or carry out full-scale tests and wish

to predict performance at different operating conditions. The variable rates

model has been implemented to facilitate this scaling process as in the rod

and ball mill models. The variations in rates also depend on recycle and feed

sizing. Hence, this model allows the user to select appropriate streams for

recycle data.

For model fitting, the original and simulated cases will usually be identical.

This is considered in detail in section A11.6.



8.2.6.3 Slurry Holdup Model

The transport of slurry through the mill is described by a function which

relates the hold-up of slurry, grate design, grate open area and mill speed to the

volumetric discharge rate through the grate (Morrell and Stephenson, 1996):

Jp = k Q 0.5 -1.25 A-0.5 0.67 D-0.25 (A11.1)

where

Jp

fractional slurry hold-up

D mill diameter (m)

A total area of the grate apertures (m2)

f fraction of critical speed

Q volumetric flowrate out of the mill (m3/hr)

mean relative radial position of the grate apertures

= ri ai

rm ai

ai

open area of all holes at a radial position ri

rm

radius of mill inside the liners

Classification by the grate is related to the effective grate aperture by a

simplified classification function. For illustrative purposes a conceptual view

of the weighted radius model is shown in Figure A11.1.

Weighted Radius For Two Grate Designs

8.2.6.4 Variable Rates Model

Relationships between the operating conditions and changes in the breakage

rate distributions within the JKMRC’s pilot mill database (Mutambo, 1993)

were developed. These results were augmented with results from full-scale

mill data in cases where the pilot mill database contained little or no variation

in the parameter of interest e.g. mill speed. To indicate the extent of the pilot



mill database, Table A11.1 summarises its details.

Range

New Feed F80 (mm) 35-140

Ball load (%) 0-12

Recycle load (%) 0-500

No. different ores 16

No. tests 52

Pilot Mill Database Details

The breakage rate distribution is described within the model using cubic

splines (Ahlberg, 1967). This gives rise to five breakage rate values each of

which relate to a particular particle size and which together characterise the

entire breakage rate distribution. The five standard particle sizes chosen are

0.25, 4, 16, 44 and 128mm which have associated with them breakage rates

which are labelled R1, R2, R3, R4 and R5 respectively.

Characterisation of the Breakage Rate Distribution

These rate curves exhibit a characteristic shape. The coarser (R5 and R4) rates

relate to abrasive breakage while the finer rates R1 and R2 exhibit similar

characteristics to those of coarse ball milling, ie. predominantly impact

breakage. The pronounced dip in the rates at R3 is associated with the critical

size which may limit mill throughput by building up to excessive levels.

Typically it is in the 25-75mm range and varies with particular combinations

of feed sizing, breakage characteristics and the magnitude of the breakage

energy developed in the mill.

To determine the relationship between operating conditions and the breakage

rate distribution, the breakage rates R1-R5 were regressed against operating

conditions. The resultant equations were of the following form:



Ln (R1) = (k11

+ k12

Ln(R2) - k13

Ln(R3) + JB (k14

- k15

F80) - DB)/S

b(A11.

2)

Ln (R2) = k21

+ k22

Ln(R3) - k23

Ln(R4) - k24

F80 (A11.

3)

Ln (R3) = Sa + (k

31 + k

32 Ln(R4) - k

33 R

r) /S

b(A11.

4)

Ln (R4) = Sb(k

41 + k

42 Ln(R5) + J

B(k

43 - k

44F80 (A11.

5)

Ln (R5) = Sa +S

b(k51 +k

52F80 + J

B (k

53 -k

54F80) - 3D

B) (A11.

6)

where:

Sa

rpm scaling factor

= Ln (simulated mill rpm/23.6)

Sb

fraction of critical speed scaling factor

= simulated mill fraction of critical speed/0.75

DB

ball diameter scaling factor

= Ln (simulated ball diameter/90)

JB

% of total mill volume occupied by balls and associated voids

Rr

recycle ratio

(tph recycled material_-20+4mm) /

(tph new feed + tph recycled material -20+4mm)

F80 80% passing size of new feed (mm)

kij

regression coefficients

The regression coefficients for equations (A11.2) - (A11.6) are given below and

are based on the JKMRC current database at mid 1996. As more data are

collected and our understanding of the various factors increases, these

coefficients are likely to be modified.

j k1j k2j k3j k4j k5j

1

2

3

4

5

2.504

0.397

0.597

0.192

0.002

4.682

0.468

0.327

0.0085

--

3.141

0.402

4.632

--

--

1.057

0.333

0.171

0.0014

--

1.894

0.014

0.473

0.002

--

Regression Coefficients



It can be seen from the equations that the finer size rates are functions of the

rates of the coarser sizes. Hence R1 is a function of R2 and R3 etc. The rates

can be considered as falling into 2 groups which represent the grinding media

and product size fractions. Hence the grinding media group contains the

rates R4 and R5 (related to particles >30mm) the magnitude of which affect

the throughput. The product group incorporates rates R1, R2 and R3 (related

to particles < 30mm) and the magnitude of these affects the final product size.

It is of particular note that the rates are interrelated in a complex manner and

are best understood by graphing the entire breakage rate distribution.

8.2.6.5 Effect of Key Parameters

The variable rate model allows the effects of a number of key parameters to be

considered independently.

It is worth mentioning that ‘original’ does not provide a basis for scaling in

this model as it does in rod and ball mill models. It provides a marker to

allow the user to see how much the rates have varied from the original case.

Ball Load The effect of changing ball load on the breakage rate distribution is illustrated

in Figure A11.3.

Effect of Ball Load on Breakage Rate Distribution

The resulting relationship is as expected in that by increasing the ball load the

breakage rates increase at coarser sizes but reduce at finer sizes. This has the

effect of predicting higher throughputs at coarser grinds as the ball load is

increased. However, it is commonplace to operate at too high a ball charge

often because of historical experience with softer, oxidised, surface ore. As the

ore becomes harder it may well be possible to replace balls with ore as

grinding media for more power effective operation.



Makeup Ball

Size

No significant dependence of the breakage rates on ball size was found in the

pilot mill database. The sag model does account for ball size changes in terms

of the energy provided during impact. It does this by changing the mean

grinding media-size, which in turn changes the ‘energy level‘ of the mill. This

‘energy-level‘ term is used to determine the specific energy of impact. As the

ball size is increased, therefore, the specific energy increases and hence for a

given impact event a finer product size distribution occurs. However, as the

ball size is increased the number of grinding media per tonne of charge will

decrease. As the breakage rate is related to the number of impacts provided by

the grinding media then a reduction in the breakage rate may be expected to

occur. To account for this a ball scaling factor is used. Figure A11.4

illustrates the effect of the ball size correction factor on the breakage rate

distribution.

It should be emphasised that it is usually argued that a coarser ball size will

give a higher throughput but with a coarser grind. In practice, experiments

with full-scale mills are sometimes inconclusive and mill operators see little or

no effect when experimenting with ball size. This may be due to the counter-

effect of reduced numbers of balls providing higher breakage energies when

increasing ball size. The model predicts such a response by increasing the

breakage energy and reducing the breakage rate. In some instances the one

effect may outweigh the other, in which case a response will be noted. Over

some ranges of ball sizes, however, little or no effect will be seen.

Predicted Effect of Changing Ball Size



Feed Size F80

Effects for SAG

Milling

The effect of F80 was found to be the most difficult one to evaluate as it

interacted with the ball charge level. At relatively high ball charges (10% or

more) high F80 values were detrimental as evidenced by the reduction in the

breakage rates illustrated in Figure A11.5.

Effect of F80 on Breakage Rate Distribution - (SAG mill)

Feed Size F80

Effects for

Autogenous

Milling

However in the case of autogenous grinding the pattern is different. In this

case a higher F80 promotes breakage in the coarser size fractions (Figure

A11.6). This is to be expected when it is considered that in autogenous

milling large rocks are required to break ore in the R5 size range (128mm). As

the F80 increases, this will typically result in more coarse rocks in the charge

able to break R5-size ore and hence R5 will increase. In SAG mills running

with higher ball charges, the rock component of the grinding media plays a

lesser role in dictating the breakage rate and contributes more to the rock

‘burden’ which has to be ground down. Feeds with F80 values and hence

more coarse feed rocks, can thus be expected to reduce the breakage rate.

Caution needs to be exercised, however, as it has been found that the F80 is

not always a good indication of the feed size distribution. This is particularly

noticeable with autogenous mills whose performance may fluctuate

considerably yet maintain a reasonably constant F80. In such cases the

distribution changes systematically with performance and that typically

higher proportions of 25-50mm material in the feed result in lower feedrates,

ie. less sub-grate size material is present in the feed and more near size

material has to be broken.



Effect of F80 on Breakage Rate Distribution - (AG mill)

Effect of Recycle

Load

Recycle loads broadly fall into 2 categories viz.:

1. Coarse recycles from trommels, vibrating screens and recycle crushers

which typically comprise only -20 + 4 mm material and have P80 values of

the order of 8 - 12mm,

2. Fine recycles from hydrocyclones and DSM screens which are

predominantly –4 mm material and have P80 values of the order of 0.2 - 0.5

mm.

It has been found that the amount of recycled material in the -20 + 4 mm size

range is inversely related to the amount of breakage that this material is

subjected to. This can be explained if one considers that these rocks are

broken by coarser rocks and balls whose frequency does not appreciably

change with changes in recycle load. However as the amount of recycled -20

+ 4 mm rock increases, the amount of this size material in the load will

increase. As the breakage rate in a given size class is related to the ratio of the

number of coarser rocks and balls to the number of rocks in the given size

class, then increasing the -20 + 4 mm recycle will result in a drop in the

breakage rate in this size range (R3 size = 16 mm). The changes in the

breakage rate distribution as the coarser recycle increases is illustrated in

Figure A11.7. Interestingly, recycle of fine material ie. –4 mm did not correlate

with any of the breakage rates. This may be related to the breakage mode of

this material which is believed to be dominated by attrition.

Where the material has been recycle crushed, it is considered to have similar

properties to new feed and is not included as -20 +4 mm recycle.



Effect of Recycle Load on Breakage Rate Distribution

Recycle Control

in V5

For the most part, the Version 5 model is identical with the Variable Rates

SAG model in Version 4. There are, however, a couple of important

differences which relate to control of recycle of –20 +4mm material on the

grinding rates.

As for V4, the User inputs new feed rate tonnes per hour and 80% passing

size for Simulated and “Original” mills.

Recycle Options – In Version 4, there are two implied switches.

The first is “Fixed Recycle”. If the User inputs a Fixed Recycle tonnage, all

simulations will use this value to calculate the recycle ratio.

Version 5 uses this implied switch as well i.e. the fixed recycle tonnage value

is set to zero to allow for simulated recycle.

The second implied switch in Version 4 is to select one (or more) recycle

streams from the flowsheet. In version 5, this switch is now explicit as “Use

Recycle in Calculations”. If this switch is set to one, the actual recycle is now

calculated by the model as the difference between –20 +4mm in new feed

(specified by the user) and in the total feed to the SAG mill.

Hence the User uses the Ore Feeder size marker to estimate % -20mm and % -

4mm and enters the difference into the appropriate field on the SAG model.

Comment. The effect of recycle has always been difficult to model and it also

the subject of current research. It provides some compensation for recycle

material ‘survivors’ being likely to be somewhat ‘harder’ than new feed

particles in the same size fraction.



However, if the recycle stream is crushed, new flaws will be generated and the

original feed properties retained. Therefore it is recommended that ‘Use

Recycle …. ‘ be turned off when a recycle crusher is used, with the following

note of caution. If K1 is larger than 4mm, a proportion of recycle crusher feed

will not be crushed. The bypassed –20 +4mm can be compensated for by

iteratively adding the ‘new’ –20 +4mm in the crusher product to the new feed

% of –20 +4mm.

Excessive fine recycle may make this model unstable. However, excessive fine

recycle will often make real AG/SAG mills unstable and it a consequence of a

realistic model.

Mill Speed/Mill

Diameter

The breakage rate is related to the number of size reduction events per particle,

per unit time and is hence a frequency. This in turn must be related to the

frequency with which the mill rotates (rpm). A scaling factor is therefore

applied to account for changes in the rotational rate. For a given fraction of

critical speed the rpm decreases with mill diameter0.5 and hence this scaling

factor will also change with mill diameter. All else being equal, therefore, a

larger diameter mill will have a lower breakage rate than a smaller unit.

However it is pointed out that the JKMRC model inherently scales on the basis

of breakage energy which it relates to mill diameter. Therefore, whereas a

larger diameter mill will have a lower breakage rate it will have a higher

breakage energy.

In a given mill as the rpm changes, apart from the rotational rate, the shape of

the grinding charge will also change in line with the fraction of critical speed

(Morrell, 1996). Typically as the fraction of critical speed increases the charge

is subjected to increased lift and hence impact breakage is enhanced. It is at

the expense of attrition breakage which is normally associated with cascading

motion and which is prevalent at lower speeds. To account for these effects a

further scaling factor is applied which is based on the fraction of critical

speed. Figure A11.8 illustrates the predicted changes in the breakage rate

distribution as speed is changed.



Predicted Effect of Changing Speed on the Breakage Rate Distribution

Mill Power The variable rates model allows the user to specify the conical slope inside the

liners of each mill end. The mill power estimate includes the conical ends

(Morrell, 1996).

8.2.6.6 Parameter Fitting - Variable Rates Model

Parameters

Fitting Single

Data Sets

Model fitting the variable rates model is quite similar to fitting the Leung

model (A9). The defaults for the original mill grinding rates are all set to zero,

ie. the intercepts of the rate equations (Table A11.2) are included in the model.

Hence the fitted rates indicate how far the measured mill is operating from

“typical” conditions. The recommend strategy is to first fit xg and xm with

the grinding rate intercepts set to zero. If the mill has pebble ports, set the

initial pebble port size to the largest measured particle in the mill discharge. If



the xg and xm fit is plausible, add the pebble port size (PPSize). Use the

measured open areas for pebble ports and grates and the measured weighted

radius/mean relative radial position for the grates. Note that the grate open

area includes grates and pebble ports. The recycle streams are selected from

the unit menu.

The measured recycle rate (-20 +4 mm) should also be entered as data. (When

this field is zero, the calculated recycle is used. This is appropriate for

simulation).

The new feed size (F80) should be noted and entered for both Sim(ulated) and

Org(inal) mills as should all of the other measured mill data.

If the xg, xm and PP (pebble port) size fit is plausible, adjust the scale factors

on Breakage Rate “Constants” to 0.1 and include them in the next fit.

The open area fractions (Grate OA) can be selected to fit. They are only suited

to matching wear conditions and should not be fitted together with grate or

pebble port sizes as the parameters are likely to interact quite severely.

Given good data and ore characterisation this model will often predict the

measured results quite well and model fitting is very simple.

Remember – xg, xm and PP size are all square mesh equivalent sizes.

Therefore, aperture shape and particle shape will interact. A slabby particle

will appear much larger to a square mesh screen than to a slotted grate

aperture!

Fitting Multiple

Data Sets

A comprehensive pilot test program will produce data over a range of

operational conditions. For sophisticated users, the variable rates model

allows several sets of pilot data to be analysed simultaneously.

The first step is to analyse each set by using its own select list. This should

identify any data problems. Then add each data set onto a combined select

list for master slave fitting.

One of the pilot data sets is selected as a base case. For this set, simulated and

original inputs are the same. For the other sets, change the simulated mill

conditions as required (eg. Ball load) and use the base case original mill

conditions in all tests. Add all of the measured load and product streams to

the model fit data list. Use the master/slave capability to simultaneously fit,

xg, xm, PPort size and grinding rate intercepts to all data sets at once.

Notes:

a fast computer (Pentium 166 or better) is required for three or more SAG

data sets

Multi-fit capability is not available in Version 5. However, the number of

fittable sets of port data will be expanded in later releases.

This approach can also be used to simultaneously analyse several sets of

operating plant data, even between different sizes of mills treating similar

ores.

In either case, a good overall fit indicates a model which can be used for

prediction over a wide range of operating conditions.

A poor overall fit, particularly if the grinding rates are lower than typical

(negative intercepts) may indicate shortcomings in data collection. More

seriously, it may also indicate more significant problems such as poor liner



design or inadequate pulp transport capacity (i.e. pulp lifters).

Larger rates may indicate particularly good practice or at the coarse knots,

decreasing ore competence at coarser sizes.

8.2.6.7 Variable Rates for Simulation & Design

This model is quite complex and a good appreciation of both the model and

SAG mill operations are recommended before use for design.

Comprehensive industrial research work over the last decade has built up the

database for this model and exposed some conceptual weaknesses which are

being addressed with two new models. However, the variable rates model is

now a powerful tool for data analysis, circuit evaluation and AG/SAG mill

design.

The following points should be noted.

Recycle Streams Up to three recycle streams can be selected from the model menu. These

should be recycles which actually go into the mill, eg. Recycle crusher

product, not feed. The “Fixed Recycle” input should be set to zero for

simulation to allow the calculated flow of -20 +4mm to be used. (Input the

measured flow for model fitting).

Where the material has been recycle crushed, it is considered to have similar

properties to new feed and is not included as -20 +4 mm recycle.

NB: V5 handles recycle loads differently from V4. See pages 106-107 for

details of the differences.

Load Limits The feed trunnion diameter indicates the maximum volumetric load limit. If

the simulated mill limits at a lower level than the actual mill, reduce this

diameter.

Beyond a certain load, the power model is unlikely to be reliable and the

power estimates are set to zero.

Grate Flow

Limits (Mass

Transfer “Law”)

The flow correlation detailed in A11.3 provides a maximum flow estimate at

the simulated mill load. The user may enter a design maximum load level for

which a maximum flowrate estimate is also calculated. These estimates relate

to flow through the grate. They assume that the pulp lifters can remove all of

the grate discharge. This is not always true for mills operating in closed

circuit with cyclone or fine screens.

If the simulated flow exceeds the maximum, the mill will likely fill up with

fines and go into overload as the slurry pool reduces impact breakage. This

effect is not simulated by the model.

Feed Size

Considerations

The F80 values for new feed for both simulated and original mills are entered

by the user.

For design, a reasonable estimate of F80 is often difficult. Power based

equations typically divide by the feed size so the assumption becomes

unimportant but real mills are sensitive to feed sizing as are accurate models.

The JK database shows reasonably systematic dependence of AG/SAG F80

(crusher P80) with all hardness measures. The harder an ore, the coarser the

resulting crusher product at the same crusher closed side setting. The best

correlation is with the JK abrasion parameter ta.



For a design case, the F80 of the feed can be estimated from the measured ta

with a standard deviation of about 10% of the primary crusher closed side

setting.

F80 (mm) = { css - 78.7 - 28.4 ln (ta) } (A11.7)

s.d. = 0.1 css

This is not a perfect answer, as the size distribution slope also varies as

shown below.

Typical AG/SAG mill feed sizings

The size converter model (see Appendix A10) can be used to adjust from a

similar ore to the target range for simulation.

(Note that it is also possible to conduct a test in a pilot adit to estimate the

likely run of mine size distribution. This distribution can be fed to the crusher

model to predict the mill feed distribution. Contact JKTech for assistance with

test blast design.)

The Variable Rates SAG mill model now warns if the simulated void fill

fraction is >=1 and if the simulated load volume is more than 0.3% different

from the measured value


This model does not take account of the variation in breakage energy at

different mill loads. Therefore pilot and industrial operation should be

measured at realistic operating loads (ie. >20%). As noted earlier, pulp lifter

capacity may limit before maximum grate capacity is reached.

The single number grate characterisation (Mean relative radial position) is a

useful approximation. However, it should be used with actual grate designs,

not hypothetical variations which may not be able to be manufactured. As the

database of very large mills expands, it is becoming apparent that the charge

in a large coarse feed mill restricts the maximum circulating load. Hence for



mills 11m in diameter (or larger) treating coarse feed, the simulated circulating

load should be restricted to 25% of new feed rate. This can be done by

reducing the grate open area parameter. This is an area of continuing research

at JKMRC.

With the large database of SAG mill test work, it is clear that maximum

throughput does not always correspond to maximum mill power draw or

maximum mill load.

For hard ores, maximum throughput requires sufficient impact energy at the

toe of the charge. Hence the maximum throughput (at maximum discharge

coarseness) will often occur between 20 and 30% volume mill load.

Research at JKMRC is developing models which will account for this effect

and others such as the difficulty of removing pebbles for crushing from very

large mills. For mills of larger diameter than 10m, a maximum recycle crusher

flow of less than 25% of new feed rate is recommended as a constraint on

simulations. (Mills with very fine feed and large grates may exceed this

estimate)

Manipulating the SAG mill feed size distribution by pre-crushing is another

way of shifting the throughput/product relationship for hard ores.

A limitation has been found on the accuracy of the response of the rate

equations to changes in F80, particularly if the new feed F80 is outside the

range of the data base. The recommended F80 for use in the model is

calculated from the equation:

F80 = 71.3 – 28.4 * ln (ta)

This F80 value should be used as the Reference F80 value on the Recycles tab

in the Variable Rates SAG Model equipment window.

It has also been found that if the aperture of a grate is above 36 mm, then the

grate needs to be modelled as a series of pebble ports because modelling it as a

grate can lead to optimistic throughput predictions by JKSimMet.

As with model 430 there is not an explicit maximum for the mill load.

However, a warning will be flagged if the total load (ie. balls and pulp)

exceeds 40% by volume. If the total load exceeds 60% by volume an error will

be flagged and the model calculations will be stopped.



8.2.6.9 Variable Rates SAG Model Printout



8.2.6.10 References

Ahlberg J H, Nilson, E N & Walsh, J L, 1967. The Theory of Splines and Their

Applications. Mathematics in Science and Engineering, 38, Academic

Press, New York and London

Andersen J S, 1989. Development of a Cone Crusher Model. M.Eng.Sc Thesis,

University of Queensland.

Leung. K, Morrison R D & Whiten W J, 1987. 1987. An Energy Based Ore

Specific Model for Autogenous and Semi-autogenous Grinding Mills.

Copper 87, Santiago Chile.

Morrell, S. 1996. Power Draw of Wet Tumbling Mills and its Relationship to

Charge Dynamics. Part I: A Continuum Approach to Mathematical

Modelling of Mill Power Draw. Trans. Instn. Min.Metall, 105, C43-53.

Morrell S & Stephenson I, 1996. Slurry Discharge Capacity of Autogenous and

Semi-autogenous Mills and the Effect of Grate Design. Int. J. Miner.

Process. (In press).

Morrell S & Morrison R D, 1989. Ore Charge, Ball Load and Material Flow

Effects on an Energy Based SAG Mill Model. Presented SAG 1989,

University of British Columbia. Editors. Mular & Agar.



Morrell S & Morrison R D, 1996. AG and SAG Mill Circuit Selection and

Design by Simulation. SAG 96, edited Mular, Barrett and Knight,

Vancouver 769-790.

Mutambo. J, 1993. Further Development of an Autogenous and Semi-

autogenous Mill Model. M. Eng Sci. Thesis. University of Queensland

(unpublished).

Needham T M & Folland G.V. 1994. Grinding Circuit Expansion at Kidston

Gold Mine. Presented at SME Annual Meeting, Albuquerque, New

Mexico. February 14 -17.

8.2.7 High Pressure Grinding Rolls (Model 402)

HPGR Model This chapter contains a description of the HPGR model.


The high pressure grinding rolls crusher (HPGR) - also known as the roller

press or roller mill - was invented by Klaus Schönert in Germany as an

outcome of his fundamental research on rock fracture (Schönert 1988). The

device has been most widely used in cement clinker grinding in Europe, but is

beginning to find application also in mineral processing. One of the first such

applications was in diamond ore processing in Southern Africa and latterly

in Australia, where it was shown that the device offered some degree of

selective liberation of the diamond from the host rock. However the claimed

advantage for most mineral processing operations is the very high reduction

ratio achieved, and the favourable specific energy consumption, compared to

conventional technologies. Some evidence has also been reported for

downstream benefits such as reduced grinding strength and improved

leachability due to microcracking (Knecht 1994).

Potential applications therefore include preparation of material for fine

grinding, replacement of tertiary crushing, rod milling and primary ball

milling in primary grinding, and the attainment of enhanced leaching

performance. The general principle is illustrated in the figure below.

Figure A12.1 - The High Pressure Grinding Rolls (Roller Mill)

Schönert’s research has shown that the most efficient way to fracture a rock

mechanically is to load it between two opposing platens until it fails. One



way to do this at a high throughput is to compress a bed of such particles

between two contra-rotating driven rolls. In industrial practice these rolls can

be very large, up to 2.8 m in diameter. One roll is mounted on fixed bearings,

and the other can move linearly against a hydraulic ram or (in small

machines) a spring.

The hydraulics are set to deliver a particular pressure to the bed of particles

passing through the machine, compressing it to a density greater than 70% by

volume. This pressure, which usually exceeds 50 MPa, controls the size

reduction in the machine.

The material leaves as a compressed cake (flake), which may have to be de-

agglomerated prior to further processing. Particular care must be taken to do

this correctly when determining a product size distribution.

The preferred method is to break-up the cake using a 2 or 3 mm screen, take

representative samples and then to use an ultrasonic bath to de-agglomerate

the particles. De-agglomeration can be completed in either water or acetone

but preferably the latter. The objective is to produce a repeatable size

distribution without additional comminution.

8.2.7.2 Model Structure

Underlying the structure of the size reduction model are three assumptions

about the inherent breakage mechanisms that occur in HPGRs, as illustrated

in the Figure below.

Pre-crusher If particles are bigger than a certain critical size they will be broken directly by

the roll faces as would occur in a conventional rolls crusher. The breakage in

this zone can be considered as analogous to a ‘pre-crusher’, the products from

which may subsequently pass to a region where a bed under compression has

formed. The boundary between the pre-crusher and bed compression regions

is defined by a critical gap (xc).

Edge Effect

Crusher

Breakage at the edge of the rolls is different to that at the centre and conforms

more to that experienced in a conventional rolls crusher. This is the so-called

‘edge effect’ which defines the proportion of relatively coarse particles usually

seen in HPGR products. Its existence has been explained by the pressure

gradient across the width of the roll and the static confinement of the ore at

the edges of the rolls which the cheek-plates provide.

Compressive

Bed Crusher

At some point away from the edges of the rolls, and extending upwards from

the area of minimum gap (xg) to an area bounded by the critical gap (x

c), is a

compression zone where breakage conditions are similar to those experienced

in a compressed packed bed.

From a modelling viewpoint these assumptions can be accommodated in the

conceptual structure shown in the figure below. Feed firstly passes to the

‘pre-crusher’. Particles with diameters that exceed the critical gap (xc) are

crushed below this size in a single particle breakage mode. The products from

this breakage then combine with feed particles that are smaller than xc. A

proportion is then diverted to another single particle crusher stage where all

particles greater than the minimum gap (xg) are crushed to below this size.

The remainder are diverted to a compression stage where all particles greater

than xg are crushed below this size but in a compressed bed mode.



All products then combine to produce the final HPGR product.

Figure A12.2 - Schematic Structure of the HPGR Model

8.2.7.3 Breakage Processes

HPGR Model The model contains three breakage processes and one splitting process

between the edge and compressed bed zones. For the breakage processes the

JKSimMet crusher model is used to describe the size reduction. Four model

parameters are required for each breakage process: K1, K

2 and K

3 and t

10. The

first three are used to describe the probability that a particle will be broken

whilst the t10

is used to describe the product size distribution that results. For

a detailed model description, refer to the Crusher Models section of this

Appendix.

t10

Definition The t10

is defined as the percentage passing one tenth of the original particle

size in the product after breakage. Other tn

parameters can be similarly

obtained from a product size distribution, eg. t2 is the percentage passing one

half of the original particle size. From breakage tests the t10

and a number of

other tn values are determined from the breakage products. These values are

stored in tabular form in the model which, given a value of t10

, uses spline

interpolation to determine the associated tn values and hence reconstructs the

entire product size distribution.

Pre-crushing For the pre-crushing process, breakage of particles is assumed to be in single

particle mode in which rocks are nipped directly by the faces of the rolls,

similar to a conventional rolls crusher. The parameters used to describe

crushing in this zone are determined from tests conducted in a conventional

(non-HPGR) laboratory rolls crusher and single particle breakage tests, and

remain constant in the model fitting and scale-up. The parameter K2 is set as

the critical gap xc, which is defined by Morrell et al (1997) by the expression

343



5.0

c

gg2c

Dx 4 - ) x+ D() x+ (D 5.0x gg

(A12.1)

where xg is the working gap, D is roll diameter,

c is bulk density of feed and

g is flake density.

Figure A12.3 - HPGR Schematic Showing Compression or Nip Angle

In the edge zones, rock breakage is also assumed to take place in single

particle mode. The parameters used to describe crushing in this zone are the

same as those used in the pre-crushing zone, except for K2, which now takes

the value of the working gap xg.

Compressed Bed

Breakage

In the compressed bed crushing zone on the other hand, size reduction is

assumed to be similar to that experienced by a bed of particles in a piston

press. The parameters used to describe size reduction are determined from

tests in a laboratory or pilot scale HPGR machine combined with breakage

tests in a piston press. The piston press tests provide information on the

relationship between size reduction and energy input in a compressed bed.

They also provide a description of the characteristic shape of the product size

distribution. If the piston press tests are not available, then the results from

the single particle Drop Weight test may be used to determine the Compressed

Bed Breakage Function (see next topic )

The parameter K2

for the compressed bed crushing is the working gap xg,

whilst K1 is set as zero.

The parameters K3 and t

10 are fitted to the laboratory scale HPGR test data.

These are the only two breakage parameters required to be fitted to laboratory

data.

Edge Crushing

Bypass

The last sub-process in the model is the split to the edge and compressed bed

zones. The edge zones are associated with the drop in pressure that is

experienced towards the edge of the rolls. Their extent is assumed to be a

function of the working gap. The fraction of feed that is crushed in the edge

zones (f) can therefore be expressed as:

f = g (xg/L) (A12.2)

where g is split factor and L is the roll length. Using pilot scale HPGR test

results where sizing data of both pure flake and total product were available,

the split factor g was found to be approximately constant with a value of 3.4.

407



In physical terms this means that the edge effect zone extended from the edge

of the roll a distance equivalent to 1.7 times that of the working gap. By sizing

the pure flake and total products from lab/pilot test results, f can be

determined experimentally. Recent work suggests that the fraction of material

being subjected to edge crushing is usually about 10%. Thus, the model may

be simplified by manipulating g (split factor) to ensure that 10% of the feed

reports to the edge crushing zone.

8.2.7.4 Compressed Bed Breakage Function

The product size distributions produced at different energy inputs (or

reduction ratios) can be characterised by a family of “t” curves. Measurement

and analysis for impact breakage is described in the Crusher Models section

.

This approach can be extended to predict required breakage power and scaled

to net crushing power using an efficiency factor., typically - 1.25 (see the

Crusher Model topics Breakage Parameters and Crusher Power

Predictions ).

Single Particle

Impact Breakage

Data

t10 t75 t50 t25 t4 t2

10.0 6.05 7.94 12.60 46.70 74.60

20.0 8.33 10.90 17.30 62.60 90.30

30.0 10.0 13.10 20.70 74.50 99.20

This approach can be extended to compressive breakage by using a piston

press to compress closely sized fractions 24

in a controlled manner. The

resulting products are sized and fitted to a spline surface. This surface can be

regenerated by the model from a matrix of spline function values. These

values are input to the model as

Compressed Bed

Breakage Test

t10 t75 t50 t25 t4 t2

10.0 4.04 6.48 7.51 17.65 35.44

30.0 13.53 19.71 22.24 41.35 58.36

50.0 23.02 31.91 38.00 52.37 69.01

It can be clearly seen that these breakage models are different. The power

requirements can also be characterised with particle size dependence if

required and also related to motor power (see the section on Power Draw ).

8.2.7.5 Throughput

Throughput is controlled principally by roll dimensions, speed and profile,

and material characteristics such as size hardness and particle-roll friction

(and thus nip-angle). The profile and material of the roll surface is important

in controlling both wear and machine performance, and various options are

offered by the different manufacturers.

The rolls throughput can be theoretically expressed as

Q = 3600 U L xgf

g (A12.3)

where

346

348

348

410



Q mass throughput (tph)

U circumferential velocity of the rolls (m/s)

L length of rolls (m)

xgf

working gap (m) – from the flake thickness measurements

g flake density (t/m3)

Note that equation A12.3 does not take into account the slip between feed

material and the rolls surface, which can be influenced by the feed

characteristics (particle size and size distribution, moisture, etc). The figure

below shows the deviation between measured throughput and throughput

calculated using Equation A12.1 for primary diamondiferous ore treated

through a 100 mm Polysius laboratory scale HPGR. It is obvious that

Equation A12.3 over-predicts the HPGR throughput at high rolls speed,

which may indicate that slip exists in the HPGR operation at these speeds.

Figure A12.4 - Deviation of the Throughput Calculated from Equation

A12.4 for Diamondiferous Ore Treated through a Laboratory HPGR at

Various Speeds

To correct for the slip effect it is considered that for a specific feed the slip is a

function of the rolls speed and the relative working gap (dimensionless)

which is defined as xg /D, where D is the rolls diameter.

The figure below plots the correction factor c, (c = Qm

/Qc, where Q

m is the

measured throughput and Qc is the throughput calculated by Equation A12.3)

versus the product of the speed and the dimensionless gap (U * xg/D) for the

Diamondiferous ore using the laboratory HPGR data. A linear regression on

the plot was obtained and Equation A12.3 was accordingly modified as:

Q = 3600 U L xg

g c (A12.4)



where c is the correction factor determined from Figure A12.5 below.

Recent work by Schonert (2000) suggests that under normal operating

conditions, slip does not occur in the compression zone. If normal operating

conditions are assured, then the correction factor should be set to 1.0.

Figure A12.5 - Throughput Correction Factor for Diamondiferous Ore

Treated through a Laboratory Scale HPGR



Figure A12.6 - Prediction of Throughput for Two Pilot Scale HPGRs from

Equation A12.4 with Model Parameter c Calibrated Using Laboratory

Scale HPGR data

Using Equation A12.4 with c determined from Figure A12.5 the throughput's

for a laboratory scale HPGR (D = 0.25 m) and two pilot scale HPGRs (KHD, D

= 0.8 m; Krupp Polysius, D = 0.71 m) were predicted. A comparison between

the calculated and the measured throughput's is given in Figure A12.6. The

rolls speeds varied from 0.29 m/s to 3.1 m/s, rolls length from 0.1 m to 0.21 m,

rolls diameters from 0.25 m to 0.80 m, and working gaps from 3 mm to 23 mm.

Figure A12.6 shows that good prediction of throughput has been achieved by

the model over the wide range of conditions tested.

8.2.7.6 Power Draw

Conventional

Crusher Power

The impact size reduction model contains an energy balance equation

(Andersen and Napier-Munn, 1988) which ensures that the energy for size

reduction is compatible with that provided by the motor. The t10

parameter is

related to the specific energy used by the machine and will follow a curve

described by the equation:

t10

= A (1 - e-bEcs) (A12.5)

where A and b are parameters and Ecs is the specific energy.

HPGR Crusher

Power

In the size reduction model the two parameters K3

and t10

were fitted to the

laboratory scale HPGR power data. It was found that the fitted t10

's for 24 sets

of Diamondiferous ore tests under various rolls speeds and feed size

conditions fell on a t10

v Ecs master curve, as shown in Figure A12.7

Equation A12.5 was hence fitted to these data to generate the A, b parameters,

which are used for the scale-up as will be demonstrated in the next section. In



JKSimMet, the points for t10

= 10, 30 and 50 are placed in the Compressive

Breakage Specific Community Energy Matrix.

Figure A12.7 - The Fitted t10 vs Specific Energy Ecs for Diamondiferous

Ore Treated through a Laboratory HPGR

A power coefficient kp is required which relates the measured power to that

predicted by the model for size reduction. This model uses the specific energy

(kWh/t) and associated t10

values from the piston press breakage

experiments. From these it calculates the overall specific energy in a piston

press. The difference between this value and that observed from the motor is

accommodated by kp, ie. k

p is the ratio of the observed to the theoretical piston

press specific energy. This coefficient has been found to be reasonably

constant over a range of specific energies but increases rapidly beyond a

certain limiting value. This is shown in Figure A12.8 for the 24 sets of data.



Figure A12.8 - Relationship between Power Coefficient (kp) and Specific

Energy for Diamondiferous Ore Treated Through a Laboratory Machine .

(Where kp = Observed power/Piston Power)

Power Draw vs

Working Gap

The prediction of the working gap xg

is also required for simulation. The

working gap depends on pressure and power draw.

Working Gap/

Specific Energy

Relationship

This relationship is developed from the laboratory/pilot scale test. The

specific motor energy is plotted against the working gap.

The parameters rc and rg in Equation A12.2 are functions of feed type,

operating conditions (eg working pressure) and the roll surface (eg smooth,

chevroned, studded). Therefore, provided the pilot scale or the full scale

machines are operating under similar conditions to the laboratory unit, then

xg will be proportional to the diameter of the rolls. The principal dependence

of the working gap will be on the working pressure, with the gap reducing as

the pressure increases. As working pressure is directly related to specific

energy, then it will be found that as the specific energy increases the gap will

decrease. An example of this is shown in Figure A12.9 for Diamondiferous

ore treated through a laboratory machine.

405



Figure A12.9 - Relationship between Working Gap and Specific Energy

for Diamondiferous Ore Treated Through a Laboratory Machine

8.2.7.7 HPGR Model Printout



8.2.7.8 Fitting the HPGR Model

SpFact

K1H

T10H

Power Coeff. H

Split Factor (g)

(SpFact)

This factor determines the proportion of material that is crushed in bypass

mode. This is usually 1.7 times the effective gap at each end, the default total

value being 3.4. (See Breakage Processes )

Setting the split factor to zero and running a simulation generates the size

distribution expected from pure compression crushing, ie. “pure flake” and

may be compared with (or fitted to) an actual sample taken from the centre of

the roll discharge.

Pre and Edge

Crusher Model

Parameters

(K1H & T10H)

Using the same feed material as for the pilot/lab HPGR test, laboratory roll

crusher is operated at close to the nipping gap and the working gap of the

HPGR.

The Whiten/Awachie/Anderson crusher model is used to derive K1

and

t10

where K2 is the crusher gap and K

3 is set at 2.3.

The ratio K1/K

2 is the input to the pre crush and edge effect models along

with the fitted t10

values. It is unlikely that power can be measured with

sufficient accuracy in this test to justify using other than the default power

factor of 1.25.

Throughput

Relationship

As noted previously , throughput is strongly controlled by geometry at low

throughput's and by slippage at high throughput's. Pilot or laboratory scale

tests can be used to derive the slope and intercept for the slip correction factor

Cp.

The model defaults are for smooth rolls. It is highly likely that different roll

surfaces will generate different correction factors.

405

343

407



Compressed Bed

Breakage

(t10 HPGR)

Breakage within the compressed bed is assumed to be uniform and able to be

described by a single parameter t10

. The t10

parameter will increase as the

reduction ratio increases. In compression, all particles are assumed to be able

to be selected for breakage ie. K1 = 0 and every particle larger than the working

gap will always be broken, ie. K2

= calculated Working Gap.

Power Model

Fitting

The HPGR model takes a somewhat circuitous approach to power modelling.

As noted previously, the combination of piston press tests and laboratory/

pilot scale HPGR produces a relationship between the compressive bed t10

and net motor power (Figure A12.7 ).

Developing this relationship requires some modelling using the Andersen/

Whiten model . The objective is to find a t10

for each data set with K2 set to

the working gap and K3 a constant value over all sets. To do this, enter all sets

of data into one test, master slave K3, set K

2 to working gap and fit each of the

t10

values. This provides a set of t10

values which can be plotted against the

motor power per tonne (Ecs) corrected for no load and the power drawn by

pre-crush and edge crushing (as in Figure A12.7 ). Equation A12.5 is fitted

to this data with A=100 and Ecs values calculated at t10

=10, 30 and 50 for

input into the Compressed Bed Breakage Matrix.

This relationship allows compressive power draw to be calculated for any

set of K1, K

2, K

3 and t

10 values. Figure A12.7 shows the power coefficient

(observed motor power divided by calculated “piston” power) for a range of

specific energy inputs, expressed as kWh/t.

If this model was ideal, the coefficient would be constant. Between zero and 5

kWh/t it is approximately constant at say 2.5 and increases rapidly at high

powers (ie. the crusher becomes less energy efficient). More energy is

converted into heat and does not result in further comminution.

8.2.7.9 Scaling the HPGR Model

To predict the performance of pilot scale and full scale HPGRs the model is

firstly calibrated using the results from the laboratory, conventional rolls,

single particle breakage and piston bed breakage test. Figure A12.10

illustrates the scale-up procedures. Also shown in Figure A12.10 are the

values of the parameters obtained from the calibration, which have been used

to predict the two pilot scale units and one full size machines treating a

Diamondiferous ore (Morrell, Shi and Tondo, 1997).

410

343

410

348



Figure A12.10 - Schematic of the Model Algorithm and Scale-up Procedure

The full scale-up procedure is implemented in JKSimMet. When running the

simulations of pilot scale or of full scale machines, the parameter K3

for the

compressed bed crushing zone is automatically adjusted until the model

predicts the same power draw as was originally chosen for the simulation.

As a result, the calculated power draw is identical to that observed, and the

product size distribution is predicted based on this power consumption.

In the simulation the maximum throughput of a scale-up HPGR is calculated

using the throughput model (Equation A12.4 ) with the correction factor c407



determined in the laboratory unit with similar rolls surface on the same type

of ore. The required power is then calculated from the maximum throughput

and the specific energy selected. The model is iterated until the breakage

power, which is the sum of the power used in the three sub-processes of pre-

crushing, compressed bed crushing and edge effect crushing, matches the

required power. The overall product size is then predicted based on the

breakage power.


Roll Surface Tests using a Krupp Polysius pilot roll (rolls diameter 0.71 m), with 4 mm

profiles (on the rolls) resulted in a considerably larger working gap than was

observed for the KHD pilot tests using smooth rolls. Therefore, laboratory

tests must be conducted with a rolls surface similar to that proposed on the

full scale machine.

Limited Data

Base

As only limited production scale data were available, the models need to be

further tested and validated against more real data in the future, and their

capabilities explored in case studies.

Power

Coefficient (kp)

Ideally, this coefficient should be constant. A better understanding and

(possibly) a better representation need to be developed.

8.2.7.11 Nomenclature

Symbol Meaning

cnip angle (degree)

split factor

cbulk density of feed (t/m3)

gflake density (t/m3)

c correction factor for rolls throughput

D rolls diameter (m)

Ecs specific energy (kWh/t)

f fraction of feed which is crushed in the edge zones

g split factor

K1, K2,

K3

size reduction model parameters

kppower coefficient

L rolls length (m)

Qmmeasured mass throughput (tph)

Qccalculated mass throughput without correction tph)

t10size distribution parameter



U rolls circumferential speed (m/s)

xccritical gap (m)

xgfworking gap (m).

8.2.7.12 Acknowledgements

This model was developed with the financial support of the sponsors of the

AMIRA P428 project (Application of High Pressure Grinding Rolls in Mineral

processing) including the Centre for Mining Technology and Equipment

(CMTE). Considerable assistance was also provided by the staff at KHD and

Krupp Polysius, as well as the staff and students at the JKMRC and CSIRO,

Division of Mineral products.

8.2.7.13 References

Andersen J S and. Napier-Munn T J, 1988. Power prediction for cone crushers.

Proc. 3rd Mill Ops Conf, Cobar, Aus. Inst. Min. Met.

Andersen J S, 1988. Development of a cone crusher model. M. Eng. Sc. Thesis,

University of Queensland (JKMRC).

Fuerstenau D W, Shukla A and. Kapur P C. 1991. Energy consumption and

product size distributions in choke-fed, high compression roll mills.

Int. J. Miner. Process., 32: 59-79.

Kapur P C, 1972. Self - preserving size spectra of comminuted particles. Chem.

Engng. Science, 27: 425-431.

Knecht, J, 1994. High pressure grinding rolls, a tool to optimise treatment of

refractory and oxide gold ores. Fifth Mill Operators Conf. Roxby

Downs, Oct, 51-59 (AusIMM, Melbourne)

Morrell, S, Shi F & Tondo, L. 1997. Modelling and scale-up of High Pressure

grinding rolls. IMPC Aachen.

Morrell S, Lim, W, Shi F and Tondo L. 1997. Modelling of the HPGR crusher.

SME Annual Conference, Denver, Colorado. Comminution Practices

Symposium, Ed Kawatra, 117-126.

Schönert K. 1988. A first survey of grinding with high compression roller

mills. Int J of Min Proc, 22, 401-412.

Schönert K.and Sander, U., 2000. Pressure and shear on the roller surfaces of

high pressure roller mills, Proc. XXI IMPC, Rome, Italy, Sect A4, 97 -

103.

Tondo L, 1996. Modelling of HPGR crushers. M. Eng Science Thesis,

University of Queensland (unpublished).

Whiten W J, 1972. The simulation of crushing plants with models developed

using multiple spline regression. J. South Afr. Inst. Min. Metall. 72:

257-264.



8.2.8 Size Degradation (Model 480)

Size Degradation

Model

This chapter contains a description of the Size Degradation model.


The concept of a degradation model has its origins in iron ore and coal

operations where particles may undergo significant size reduction during

mechanical handling such as dropping on to a stock pile from a conveyor or

perhaps at a conveyor transfer point.

8.2.8.2 Model Structure

The model structure is a simple representation of a single drop which results

in the particles being broken to a specified t10

value. The breakage

distribution parameter, t10

, characterises the size distribution of the broken

product. More details of this parameter and the concepts behind it are given

under the heading Crusher Models . The appearance function data

discussed in this section are required for the degradation model and these are

produced as part of the standard JKMRC Drop Weight Test.

Breakage

Distribution

Parameter (t10)

The breakage distribution parameter, t10

, is entered as a model parameter. It

must be calculated by the user and is generally based on the Energy v Size

Reduction relationship for the particular ore derived from the JKMRC Drop

Weight test.

Specific

Comminution

Energy

The Specific Comminution Energy in a drop is a function of the height of the

drop and can be calculated using the following equation:

Ecs

= 0.00272 * h (A13.1)

where:

Ecs

specific comminution energy (kWh/t)

h height of the drop (m)

Energy – Size

Reduction

Relationship

The relationship between Specific Comminution Energy and size reduction

represented by t10 is also one of the results of the JKMRC Drop Weight test.

The relationship is of the form:

t10

= A * ( 1 – exp( - b * Ecs )) (A13.2)

where:

t10

breakage distribution parameter

Ecs

specific comminution energy (kWh/t)

A & b are ore characteristic parameters

Conditioning In most cases, the damage inflicted by a second drop is less than that inflicted

by the first drop. This effect is known as conditioning. Of course, the height

of each drop is important as well as the number of drops.

Effectively, the particles become a little more resistant to impact after each

successive drop. The amount of this effective increase in resistance depends

on the ore type and on the drop heights.

346



This effect can be included in the simulation by an appropriate reduction in

the b value used in equation A13.2. For an ore that is only a little affected by

conditioning, a reduction of b to 75% of its starting value is typical. For an ore

which is significantly affected by conditioning, b is typically reduced to 40%

of its starting value.

Example The A and b values from the JKMRC Drop Weight test for the example ore are

50 and 0.5 respectively.

For a drop height of 20 m, from equation A13.1:

Ec

s

= 0.00272 * h

= 0.00272 * 20

= 0.054 kWh/t

and from equation A13.2

t1

0

= A * ( 1 – exp( - b * Ecs ))

= 50 * ( 1 – exp( - 0.5* 0.054))

= 1.33

this value of t10

is then entered into the model.

For a second 20 m drop of an ore which is strongly affected by conditioning, b

is reduced to 0.2 (40% of 0.5) and

from equation A13.2

t10

= A * ( 1 – exp( - b * Ecs ))

= 50 * ( 1 – exp( - 0.2* 0.054))

= 0.54

this value of t10

is then entered into the model for the second drop.

Use for the

Vertical Shaft

Impactor

The degradation model can be used to represent a lightly loaded Vertical Shaft

Impactor. In this case, the energy of an impact is calculated from the velocity

of the particle imparted by the rotor. This energy must be converted to units of

kWh/t before equation A13.2 can be applied.

For example, for a VSI with a rotor diameter of 0.6 m spinning at 2000 rpm, the

energy imparted to a particle leaving the rotor at its peripheral speed is:

Ec

s

= 0.5 * m * v2 / ( 3600 * m )

= 0.5 * v2/ 3600

= 0.5 * ( p * 0.6 * 2000 / 60 )2/ 3600

= 0.55 kWh/t

where:

m = particle mass (which cancels out)



Ecs

= specific comminution energy (kWh/t)

v = peripheral velocity of rotor (m/s)

3600 is the conversion factor for kWh/t

The Ecs

value is substituted into equation A13.2 to calculate t10 for use in the

model.

8.2.8.3 Degredation Model Printout

Degradation Model Printout

8.2.8.4 Fitting the Degredation Model

This is a very simple model to fit, the only fittable parameter being t10

.

A typical range of starting estimates for degradation by drop is 0.2 to 0.8

depending on amenability to degradation and drop height.

A typical range of starting estimates for the VSI is 5 to 20 depending on rotor

diameter and speed and ore type.


It is recommended that the ore specific appearance function is measured by a

Drop Weight test rather than using the default values. Although the variation

of the crusher appearance function data in the JKTech data base (of ores

subjected to Drop Weight testing) is not particularly large, ore specific values

will provide better results.

If several drops actually occur, it may be better to simulate these as separate

drops than as a single drop of the total accumulated drop height, particularly

if conditioning is likely.

It should also be noted that ores which are particularly susceptible to

degradation are also likely to be degraded during the process of screening to

determine the size distribution, thus making the size distributions somewhat

doubtful.



Index- A -adding streams 72

AG model 370

- B -backing up work 18

backup copy 18

ball mill

perfect mixing model 361

- C -changing circuit 99

circuit performance 99

computer requirements 17

configurable stream overview 97

courses 19

crusher 343

crusher models 343

cursor 57

- D -data collection 230

data entry conventions 81

data structure 51

direction change for streams 72

display 58

dongle 19

drawing streams 72

- E -efficiency curve

simple 325, 326

splined 328

variable d50c 330

water & fine 326, 327

elemental assay labels 78

ending a session 99

equipment icons 52

equipment items 52

equipment labels 63

example project 18

- F -flowsheet name 61

- H -hardware key 19

hardware requirements 17

high pressure grinding rolls model 403

- I -inflexion points 72

Installation procedure 47

- L -loading a project 100

- M -maintenance agreements 19

mass balance 17

mass balancing 230

infinite division problem 268

middlings problem 267

metallurgical accounting 268

model building 56

model fitting 17

graphing results 287

printing results 287

problems 291

references 292

models 18, 343

AG 370

ball mill - perfect mixing 361

double deck screen 325

efficiency curve - variable d50c 330

high pressure grinding rolls 403

rod mill 355

SAG 370

simple efficiency - fitting 326

simple efficiency - water & fine 326

simple efficiency - water & fine - fitting 327

simple efficiency curve 325

single deck screen 317

size converter 385

size degradation 419

splined efficiency - fitting 328

Index 423


models 18, 343

splined efficiency curve 328

variable rates SAG 386

modules 18

mouse 57

- N -naming streams 72

nudging 72

- O -operatiing systems 17

operating systems 17

- P -parameters

types 273

preferences 57

project name 61

- R -redrawing flowsheet 72

restrictions 322, 330, 331, 332

Efficiency Curve Variable D50c 331

Single Deck Screen Model 322

rod mill model 355

routing of streams 72

- S -SAG model 370

sample degradation model 419

screen model

double deck 325

single deck 317

selecting a flowsheet 100

Sieve Series 175

simulation 59

results display options 15

simulation window 87

size classes 78

size converter model 385

Standard deviation 231

start up 60

stream data 94

stream data overview 97

streams 51

structure 18

structured example 18

- T -terminating a session 99

- U -units - changing 78

updates 19

- V -values from simulation 56

variable rates SAG model 386

viewing stream data 94, 97

- W -window size 60

windows 58

Endnotes 2... (after index)



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