fragmented rock

12.10.2013

Fragmentation Distribution Study of

Rock Blasting in Erdenet Open Pit Mine

1

Outline

Introducing Erdenet open pit mine and mining process

Blasting

Fragmentation measurement method

Fragmentation prediction method

Applying new design standard

Summary

2

Introduction 3

Open Pit Mine Process

Drilling

Blasting

Loading

Transportation

Crushing

Grinding

Processing Introduction

4

Blasting

One of the most important unit of open pit operation

Purpose:

To fracture solid ores and rocks, prepare the material for

excavation and transport

Blasting influences in loading, hauling and primary crushing.

Improvement of blasting results provides increase in loader

and excavator productivity due to increased diggability

capacity and increased bucket and truck fill factors.

Blasting 5

Blasting

Suitable and uniform particle size distribution results

increase in crusher and mill throughput and decrease in

energy consumption in size reduction process.

Now what is the optimum fragment size?

How can we improve blasting design ?

Blasting 6

Blasting 7

Blasting 8

Fragmentation Measurement Method

The size distribution analysis of the rock fragmentation

1. Sieving method (direct)

2. Digital Image processing method (indirect )

The size distribution analysis of the rock fragmentation by

sieving is a direct and accurate method but it is very time

consuming and costly.

Fragmentation analysis by digital image processing is a low cost

and quick method.

Fragmentation measurement method 9

Split-Desktop System

Split system is one of the digital image processing software

developed to compute the size distribution of fragmented

rock from digital images.

From muckpile,

haul truck,

waste dump,

stockpile,

conveyor belt, or any other location


Once the images are taken and saved to a computer, the

Split-Desktop software has five progressive steps for

analyzing each image

Step 1. The scaling

Step 2. The automatic delineation of the fragments

Step 3. The editing of the delineated fragments

Step 4. The calculation of the size distribution based on the

delineated fragments.

Step 5. To display the size distribution results.

Split-Desktop System


The scaling


65022 12

The Delineation


65022 13

The scaling


80101 14

The Delineation


15

The scaling


80102 16

The Delineation


80102 17

The scaling


95175 18

The Delineation


95175 19

The scaling


69025 20

The Delineation


69025 21

The Results of Combined Size Distribution


Fragmentation Prediction Method

(Kuz-Ram Model)

A common model in industry for predicting rock fragmentation size distribution by blasting

- Kuznetsov formula

median fragment size, cm

A rock factor

Qe mass of explosive being used, kg

SANFO weight strength of the explosive to ANFO

k powder factor, kg/m3

Fragmentation prediction method 24

=

(2)1/

=

(Rosin-Rammler formula)

x Screen size

n Uniformity index

- Characteristic size (63.2% passing size) R porportion of material retained on the screen

= 2.2 14

1 +

2(1

)(

)

Kuz-Ram Model


Pattern Design Amount Unit

Hole Diameter, de 250 mm

Charge Length, l 8.5 m

Burden, B 8 m

Spacing, S 8 m

Subdrilling, J 2 m

Drill Accuracy, W 0.1 m

Bench Height, L 15 m

Powder Factor, k 0.39 kg/m3

Charge Weight per Hole, Qe 355 kg/hole

Youngs Modulus, E 200 GPa

UCS 117 MPa

Specific Gravity of Rock 2.6

Specific Gravity of Explosive 0.85

Velocity of Detonation 4400 m/s

Blasting Parameters of Erdenet Open Pit Mine


Results of Kuz-Ram Model Amount Unit

Rock Factor, A 4

Median Size of Material, 25 cm

Uniformity Index, n 1.04

Characteristic Size, x 0.35 m

Max Boulder Size, (R=0.02) 1.318 m

Predicted Fragmentation Percent

Percent Oversize, >400mm 32%

Percent In Range, 0-400mm 68%

Predicted Results From Kuz-Ram Model,

(EMC blasting parameters)


Comparison Between Image Processing and Kuz-Ram Model


The Ash Design Standard

One of the classic papers in rock blasting The mechanics of

rock blasting was written by Ash. K (1963).

The value of the K ratios for each parameters such as burden,

spacing, subdrilling and stemming were calculated from the

data collected at the different rock types hole depths, hole

diameters and all grades of explosives.

Ash design standard 29

Using K ratio, determined optimum parameters that provide

improvement for size of fragment distribution.


Pattern Design Amount Unit

Hole Diameter, de 250 mm

Charge Length, L 11.5 m

Burden, B 7.5 m

Spacing, S 10 m

Subdrilling, J 2 m

Drill Accuracy, W 0.1 m

Bench Height, H 15 m

Powder Factor, k 0.47 kg/m3

Charge Weight per Hole, Qe 490 kg/hole

New Blasting Parameter


Results of Kuz-Ram Model Amount Unit

Rock Factor, A 4

Median Size of Material, 22 cm

Uniformity Index, n 1.43

Characteristic Size, x 0.29 m

Max Boulder Size, (R=0.02) 0.751 m

Predicted Fragmentation Percent

Percent Oversize, >400mm 20.5%

Percent In Range, 0-400mm 79.5%

Predicted Results of New Design

Kuz-Ram Model


Comparison Between New and Current Blasting Design

Applied to Kuz- Ram Model


Summary

Fragmentation size distribution was measured with image

processing method and was predicted by Kuz-Ram model on the EMC blasting data

Blasting design was improved by Ash design standard

Passing percent of fragmentation was increased from 68 % to 80% compare with two different blast design in Kuz-Ram model.

Explosive consumption increased 38 %,

Image processing method was limited accuracy because only using one part of muckpile image.

Using I-Site 3D Laser Scanner we can more accurately measure fragmentation distribution

Using High Speed camera we can analyze motion of blasted rock and we can improve design

34

fragmented rock

Documents

fragmentation analysis

accurate method

quick method

kgm3 fragmentation predic

sieving method direct

size distribution analysis

blasting design

scaling step