vol 9 - operations manual complete.pdf

7/21/2019 Vol 9 - Operations Manual COMPLETE.pdf

1/217

Prepared for:

Sociedad Minera Cerro Verde S.A.A.

Asiento Minero Cerro Verde - UchumayoCasilla Postal 299 Arequipa, Peru

CERRO VERDE TAILING STORAGE FACILITYFINAL DESIGN

Volume 9 Operations Manual

September 2006


2/217

September2006 Cerro Verde TSF * Operations Manual TOC-i

TABLE OF CONTENTS

Section No. Page No.

1.0 INTRODUCTION........................................................................................................................... 1 1.1 DOCUMENT PURPOSE AND OBJECTIVES ......................................................................................... 1 1.2 R EGISTERED DOCUMENT HOLDERS ...............................................................................................2 1.3 OPERATIONS MANUAL R EVIEW AND UPDATE ...............................................................................2 1.4 PROJECT HISTORY AND SCHEDULE ................................................................................................3

2.0 ROLES, RESPONSIBILITIES, AND TRAINING REQUIREMENTS.................................... 4 2.1 GENERAL .......................................................................................................................................4 2.2 ORGANIZATIONAL CHART .............................................................................................................4 2.3 R OLES AND R ESPONSIBILITIES ....................................................................................................... 4 2.4 TRAINING R EQUIREMENTS .............................................................................................................6

3.0 FACILITY DESCRIPTION .......................................................................................................... 7 3.1 BACKGROUND I NFORMATION ........................................................................................................ 7 3.2 FACILITY LOCATION AND BRIEF DESCRIPTION ..............................................................................7 3.3

SITE CONDITIONS ..........................................................................................................................8

3.3.1 Landscape and Topography..................................................................................................... 8 3.3.2 Climate and Hydrology ............................................................................................................8 3.3.3 Seismicity................................................................................................................................ 10 3.3.4 Geology .................................................................................................................................. 10

3.4 DESIGN BASIS AND CRITERIA ....................................................................................................... 11 3.4.1 Compliance of Standards and Regulations ............................................................................ 11 3.4.2 International Guidelines......................................................................................................... 16 3.4.3 Design Basis and Criteria ...................................................................................................... 16

4.0 FACILITY OPERATION............................................................................................................ 19 4.1 OBJECTIVE ................................................................................................................................... 19 4.2 TAILING PRODUCTION AND TRANSPORT ...................................................................................... 19

4.2.1 Tailing Characteristics and Production Schedule..................................................................19 4.2.2 Tailing Thickening.................................................................................................................. 20 4.2.3 Whole Tailing Pipeline..........................................................................................................21 4.2.4 Tailing Cycloning................................................................................................................... 21 4.2.5 Jacking Headers.....................................................................................................................22 4.2.6 Other Delivery Lines ..............................................................................................................22

4.3 EMBANKMENT CONSTRUCTION ................................................................................................... 22 4.3.1 Description of the Embankment .............................................................................................23 4.3.2 Embankment Design Assumptions..........................................................................................24 4.3.3 Start-up Construction.............................................................................................................24 4.3.4 Contingency Measures and Problem/Solution Matrix ...........................................................29

4.3.4.1 Insufficient Quantity of Underflow .............................................................................................. 29 4.3.4.2 Flatter or Steeper Embankment Slope .......................................................................................... 30


3/217

September2006 Cerro Verde TSF * Operations Manual TOC-ii

4.3.12.2 In-place Density and Moisture Content ........................................................................................ 44 4.3.12.3 Gradation of In-place Underflow..................................................................................................44 4.3.12.4 Compaction Characteristics of In-place Underflow......................................................................45 4.3.12.5 Slope............................................................................................................................................. 45 4.3.12.6 Freeboard......................................................................................................................................45 4.3.12.7 Erosion..........................................................................................................................................46 4.3.12.8 QA/QC Reporting.........................................................................................................................46

4.4 IMPOUNDMENT DEPOSITION PLAN ...............................................................................................47 4.4.1 Objectives............................................................................................................................... 47 4.4.2 Description............................................................................................................................. 47 4.4.3 Deposition Schedule............................................................................................................... 49 4.4.4 QA/QC....................................................................................................................................50

4.5 SUSTAINING CAPITAL ITEMS ........................................................................................................ 50 4.5.1 Drain Expansion .................................................................................................................... 51 4.5.2 QA/QC of Sustaining Capital Drain Expansions ...................................................................51 4.5.3 Header Extension ................................................................................................................... 53 4.5.4 Left Abutment Blanketing .......................................................................................................54 4.5.5 Instrumentation Expansion..................................................................................................... 56

4.5.5.1 Details of Instrument and ADAS Installation and Maintenance...................................................57 4.5.6 Geotechnical Investigations ................................................................................................... 57

4.6 WATER MANAGEMENT ................................................................................................................ 59 4.6.1 General...................................................................................................................................59

4.6.2 Reclaim Water Pond...............................................................................................................59 4.6.3 Seepage Management............................................................................................................. 61

5.0 ENVIRONMENTAL PROTECTION......................................................................................... 62 5.1 GENERAL .....................................................................................................................................62 5.2 SOILS ...........................................................................................................................................62 5.3 AIR QUALITY ............................................................................................................................... 62 5.4 VEGETATION AND W ILDLIFE ....................................................................................................... 63 5.5 WATER QUALITY .........................................................................................................................63

5.6 R ECLAMATION AND

R EHABILITATION

......................................................................................... 64 5.7 DOCUMENTATION ........................................................................................................................64

6.0 SAFETY AND SECURITY.......................................................................................................... 65 6.1 GENERAL .....................................................................................................................................65 6.2 WORKER HEALTH AND SAFETY ................................................................................................... 65 6.3 SITE SECURITY ............................................................................................................................66 6.4 EMPLOYEE TRAINING .................................................................................................................. 67 6.5 DOCUMENTATION ........................................................................................................................67

7.0 MAINTENANCE .......................................................................................................................... 68 7.1 R OUTINE MAINTENANCE .............................................................................................................68 7.2 EVENT - DRIVEN MAINTENANCE ................................................................................................... 68 7.3 DOCUMENTATION ........................................................................................................................69

8.0 FACILITY SURVEILLANCE .................................................................................................... 70 8 1 G 70


4/217

September2006 Cerro Verde TSF * Operations Manual TOC-iii

8.4.1.2 Routine Daily Inspections - Visual ............................................................................................... 74 8.4.1.3 Comprehensive Inspections ..........................................................................................................76 8.4.1.4 Intermediate Inspections............................................................................................................... 76

8.4.2 Inspection after Extreme Events.........................................................................................77 8.4.2.1 Earthquake....................................................................................................................................77 8.4.2.2 Flood............................................................................................................................................. 77 8.4.2.3 Landslide ......................................................................................................................................78

9.0 DOCUMENTATION AND REPORTING................................................................................. 79 9.1 DATABASE ................................................................................................................................... 79 9.2 FILING WRITTEN R EPORTS ..........................................................................................................79 9.3 STORING ELECTRONIC DATA ........................................................................................................ 79 9.4 R ETRIEVING ELECTRONIC DATA .................................................................................................. 80 9.5 FILING R EPORTS BY OTHERS ....................................................................................................... 80 9.6 A NNUAL OPERATIONS MANUAL UPDATE .................................................................................... 80

10.0 EMERGENCY RESPONSE PLAN ............................................................................................ 82 10.1 OVERVIEW .............................................................................................................................. 82 10.2 R ESPONSIBILITIES .................................................................................................................... 82 10.3 EMERGENCY SUPPLIES AND R ESOURCES .................................................................................84 10.4 EMERGENCY CONDITIONS ....................................................................................................... 84

10.4.1 Earthquake.........................................................................................................................84 10.4.2 Flooding............................................................................................................................. 85 10.5 FAILURE CONDITIONS .............................................................................................................86 10.5.1 Failure is in Progress ........................................................................................................86 10.5.2 Failure is Imminent............................................................................................................87 10.5.3 Failure is Developing......................................................................................................... 87

10.6 R ESPONSE ACTIONS IF THERE IS ..............................................................................................87 10.6.1 Slide on the Downstream Slope of the Embankment.......................................................... 87 10.6.2 Loss of Freeboard..............................................................................................................88 10.6.3 Excessive Seepage..............................................................................................................88

10.6.4 Excessive Embankment Settlement..................................................................................... 88 10.6.5 High Phreatic Surface in Embankment.............................................................................. 88 10.6.6 Embankment Cracking....................................................................................................... 88 10.6.7 Seeps, Sandboils, and Sinkhole Development.................................................................... 89

10.7 POST -FAILURE ACTIONS .........................................................................................................89

11.0 SCHEDULE................................................................................................................................... 90

LIST OF TABLES

Table No. Description

1-1 Operations Manual Distribution List2-1 Roles & Responsibilities2-2 Recommended Training Requirements3 1 M l i l S i C di d Y f R d


5/217


6/217

September2006 Cerro Verde TSF * Operations Manual TOC-v

11-1 TSF Construction and Operations Schedule

LIST OF APPENDICES

Appendix A OM Revision and Holders Record Appendix B Environmental Management Plan for the Tailing Storage Facility Operations Appendix C Forms Appendix D Sustaining Capital and Operations Cost


7/217

September 2006 Cerro Verde TSF* Operations Manual 1

1.0 INTRODUCTION

1.1 DOCUMENT PURPOSE AND OBJECTIVES

The purpose of this document is to serve as a reference manual for personnel involved in theconstruction and operation of the Cerro Verde Tailing Storage Facility (TSF) during its life cycle. Thedocument should be kept current and should be revised periodically. This manual was prepared byMWH in support of the detailed design of the Cerro Verde TSF that was performed during the periodfrom January 2005 to April 2006. It forms part of the following multi-volume compendiumsupporting final design of the Cerro Verde TSF:

Volume 1 Summary Report Volume 2 Geological and Geotechnical Site Investigations and Assessments

Volume 3 PMP and Rainfall Frequency Analysis

Volume 4 Seepage Analysis

Volume 5 Material Balance Analysis

Volume 6 Water Balance Analysis

Volume 7 Static and Seismic Stability Analyses Volume 8 Seepage Collection System Design

Volume 9 Operations Manual

Volume 10 Drawings

The objectives of the operations manual are to define and describe the following:

Roles and responsibilities of the personnel assigned to the facility The key components of the facility

The procedures required to construct, operate, monitor and maintain the facility so that itfunctions in accordance to its design, and meets regulatory and corporate policy obligations

Emergency response procedures

Requirements for documentation and reporting

Requirements for Quality Assurance and Quality Control (QA/QC)

This document does not address the operation and maintenance of the following facility components:


8/217


1.2 REGISTERED DOCUMENT HOLDERS

This Operations Manual will be revised, maintained and distributed by the Tailing Superintendent.

Each copy of the manual is assigned an identification number for tracking purposes. The initialdistribution list for the Operations Manual is provided in Table 1-1.

TABLE 1-1OPERATIONS MANUAL DISTRIBUTION LIST

Position Department/Company Name Copy No.

General Manager Cerro Verde Jesus Figueroa 1Operations Manager Operations Jim Vanderbeek 2

Concentrator Manager Concentrator 3Oxide Plant Superintendent Concentrator 4Tailing Superintendent Concentrator Angel Manchego 5,6

Engineering Superintendent Engineering 7Health, Safety, and

Environmental SuperintendentHealth, Safety and

Environmental 8

Maintenance Superintendent Maintenance 9Control Supervisor Concentrator 10

Cyclone Station Operator Concentrator 11Tailing Deposition System

OperatorConcentrator 12

Designer (Engineer of Record) MWH James Obermeyer 13Review Board ETRB ETRB 14

The Tailing Superintendent is responsible for maintaining an up-to-date list of registered holders ofthe Operations Manual (Table A-1 in Appendix A). Each registered holder of the Operations Manual,including the Tailing Superintendent, must acknowledge responsibility for learning the contents of thisdocument by returning a signed copy of the transmittal letter to the Tailing Superintendent within two

weeks of receipt of this document (Table A-2 in Appendix A).

1.3 OPERATIONS MANUAL REVIEW AND UPDATE

This Operations Manual will be reviewed by Sociedad Minera Cerro Verde S.A.A. (SMCV) on anannual basis to address continual improvement and changes in the conditions and operation of the

TSF. A review of the Operations Manual will also be required after a significant accident related to theoperations of the TSF.

All registered users of the Operations Manual are encouraged to provide comments and suggestionsfor improvement of the manual and the procedures specified in it. The comments and suggestionsshould be forwarded to the Tailing Superintendent and to the Designer (MWH) for consideration inthe annual review of the document. The Tailing Superintendent is responsible for reviewing, updatingand improving the manual, but no changes to the design criteria, design details, or specifications shallme made without the review and approval of MWH.


9/217


Step 4 : Communicate and coordinate the change with regulatory authorities and externalstakeholders.

Step 5 : Obtain necessary permits.

Step 6 : Modify the Operations Manual to address the change.

Step 7 : Implement the change.

Potential situations that may result in a manual review and update are evolution of the design throughcapacity change, operational efficiencies, closure requirements, performance feedback, management

changes, regulatory changes, variations of performance from design, and suggestions forimprovement. Table A-3 in Appendix A should be updated to record any revisions of this document.

1.4 PROJECT HISTORY AND SCHEDULE

SMCV is in the process of development of the Cerro Verde Primary Sulfide Project. Phelps DodgeMining Company (PD) is the majority shareholder and operator of SMCV.

In 2001 and 2002, PD initiated scoping level studies to evaluate alternative TSF sites and tailingembankment construction methods. The results of these studies were presented in reports entitledTailing Scoping Study, dated December 2001, Scoping Level Study for Tailing Deposition at A5Site, dated January 2002, and Scoping Level Study for Tailing Deposition at the A9 Site, datedMarch 2002, by URS. In 2003, Fluor completed the Cerro Verde Primary Sulfide Project FeasibilityStudy Report. Part of the report was the Tailing Embankment Feasibility Design Report by URS,dated June 2004.

As a part of the final design, SMCV contracted Montgomery Watson Harza Americas, Inc. (MWH) todevelop final designs for the civil and geotechnical elements of the TSF. The MWH work scopeconsisted of site investigations, engineering analyses, design drawings, and specifications for theStarter Dam and Seepage Collection System, and Standard Operating Procedures (SOPs) for elementsof the TSF within MWHs scope of work. Final engineering design for the TSF was performed byMWH during the period from January 2005 to April 2006. Other design components of the TSF, suchas tailing delivery system, cyclone stations, reclaim water system, and pump-back water system fromthe seepage collection system were designed by Fluor Mining and Minerals (Fluor).

Permit for construction of the TSF was obtained from the Ministry of Energy and Mining (MEM) in

September 2004. Construction of the Starter Dam was initiated in April 2005 and is scheduled to becompleted in August 2006. Concentrator start-up is scheduled for November 1, 2006. Constructionand operation of the TSF is planned to take place over a period of approximately 22 years.


10/217


2.0 ROLES, RESPONSIBILITIES, AND TRAINING REQUIREMENTS

2.1 GENERAL

A Cerro Verde TSF Management Team has been assembled to oversee the design, construction andoperation of the TSF. The management structure is based on the principles outlined in the Mining

Association of Canada Guide to the Management of Tailing Facilities. The organizational chart of theCerro Verde TSF Management Team is presented in Figure 2-1. The team will be supervised by theConcentrator Manager with support from maintenance, environmental and engineering departmentsat SMCV.

2.2 ORGANIZATIONAL CHART

Figures 2-2 and 2-3 illustrate the organizational structure that will be used to operate the TSF. TheOrganization Chart considers the following:

There will be 5 Shift Supervisors during all periods of operation of the TSF.

There will be 4 Cyclone Station Operators during all periods of operation of the TSF.

There will be 1 Tailing Embankment Specialist during all periods of operation of the TSF.

There will be 2 QA/QC Supervisors during all periods of operation of the TSF.

There will be 1 Surveyor during all periods of operation of the TSF.

There will be 18 Tailing Deposition System Operators during all daily operations of the TSF, and14 Tailing Deposition System Operators during all night operations of the TSF.

There will be an independent 3rd party engineering firm (Engineer of Record) with a full timepresence to manage and implement the QA/QC program and to monitor and documentcompliance of the operations and construction with the design requirements for the TSF. TheDesigner is preferred for this role.

2.3 ROLES AND RESPONSIBILITIES

The roles and responsibilities for each position and the authority during the operational cycle of the TSF are presented in Table 2-1.


11/217


TABLE 2-1ROLES & RESPONSIBILITIES

Position Role Responsibility Authority

Operations Manager OverallCoordination

- Senior TSF operations and construction oversight.- Provide recommendations for improvement of the tailing operations.- Coordinate with other areas of the mine that may impact the tailing operations.- Coordinate with other departments of the mine that will provide support for the tailing operations.- Maintain relationships with external stakeholders related to the TSF.- Safety/HERA oversight

Authorize dam operation and sustaining capital budgets

Concentrator Manager OverallManagement

- Senior TSF operations and construction oversight.- Coordinate with other areas of the mine that impact the tailing operations.- Coordinate with other departments of the mine that will provide support for the tailing operations.- Provide recommendations for improvement of the tailing operations.- Ensure development, implementation and application of Safety/HERA program

- Assign resources to Tailing Superintendent consistent with capital andoperational budgets- Hire/replace Tailing Superintendent- Decision to divert flows to auxiliary system during emergencies- Coordinate with other areas- Decision to shutdown concentrator and TSF during emergencies

ConcentratorSuperintendent Plant Manager - Coordinate tailing production with Tailing Superintendent

- Decision to divert flows to auxiliary system during emergencies- Decision to shutdown the Concentrator during emergencies

Tailing Superintendent Manager ofTailing System

- Participate in start-up and commissioning.- Implement Operations Manual- Develop, implement, and apply Safety/HERA program for tailing facility- Prepare reports according to the Operations Manual.- Update the Operations Manual.- Provide recommendations for improvement of the tailing operations.- Detect and communicate potential problems related to the tailing operation to upper level management.- Schedule sustaining capital investments.

- Coordinate with other areas of the mine that may impact the tailing operations.- Coordinate work of sub-contractors to operate and maintain the TSF.- Coordinate with other departments of the mine that will provide support for the tailing operations.- Monitor and update closure plan as required.- Implement activities as required by the operational permits for the TSF.- Perform monitoring according to operational requirements.- Update the Operations and Maintenance Manuals- Maintain spare parts and equipment inventory.- Maintain the document control system for the TSF.- Maintain TSF equipment maintenance records.- Stay up to date on new laws and permit requirements that relate to tailing operations.- Prepare operation and sustaining capital budgets.- Implement adjustments to the tailing pipeline operation.- Wear monitoring of the pipelines.- Update the water balance according to this Operations Manual.- Prepare and update training programs for TSF personnel.

- Decision to divert flows to auxiliary system during emergencies- Hire/replace TSF operational staff- Decision to shutdown the tailing operations during environmental

problems.

EngineeringSuperintendent TSF Stability andrepairs

- Provide input to development, implementation, and application of Safety/HERA program- Provide recommendations for improvement of the tailing operations.- Implement Project Execution Plans for sustaining capital investments.- Manage sustaining capital investment projects until they are turned over to operations.

- Implement independent review and audits of the TSF.- Implement appropriate QA/QC through an independent 3 rd party (preferably the Designer)- Provide support for monitoring the construction of the cycloned underflow raises to the TSF embankment.- Provide technical support.- Provide resources for TSF repair and cleanup.- Interpretation of operati onal monitoring results

- Carryout assigned duties / responsibilities- Recommend actions to Tailing Superintendent resulting from

interpretation of instrumentation and monitoring data

EnvironmentalSuperintendent

TSFenvironmentalcompliance /MEM reporting

- Provide input to development, implementation, and application of Safety/HERA program- Provide recommendations for improvement of the tailing operations.- Implement activities as required by the environmental permits for the TSF.- Perform monitoring according to environmental requirements.- Incorporate the TSF into the SMCV site environmental management program.- Ensure that SMCV environmental policies, guidelines and procedures are followed.- Provide environmental training and technical support for exclusive tailing facility personnel.- Interpret environmental monitoring data.- Report non-compliance to the Tailing Superintendent.- Validate environmental laboratory test results.- Download and process meteorological data collected at the project site.

Carryout assigned duties / responsibilities

MaintenanceSuperintendent

TSF pumps,electrical andpipingmaintenance

- Provide input to development, implementation, and application of Safety/HERA program- Provide recommendations for improvement of the tailing operations.- Provide emergency maintenance assistance during night shifts.

- Provide training and technical support for exclusive tailing facility maintenance personnel.- Ensure that maintenance for the TSF is performed according to SMCVBT guidelines and procedures.- Provide support to update the Operations and Maintenance Manuals- Provide support to maintain spare parts and equipment inventory.

Carry out assigned duties / responsibilities

Health and SafetySuperintendent

Facility andpersonnel healthand safety

- Provide input to development, implementation, and application of Safety/HERA program- Proactively monitor ongoing Safety/HERA program for Tailing Facility- Provide recommendations for improvement of the tailing operations.- Detect and communicate potential Health and Safety problems related to the tailing operation to upper level

management.- Provide health and safety training for exclusive TSF personnel.- Ensure that health and safety programs and policies for the TSF are performed according to SMCV guidelines and

procedures.- Incorporate the TSF into the overall SMCV site Health and Safety Plan.- Inspect the TSF related to Health and Safety requirements

- Direct health and safety plan development.- Oversee plan implementation.- Ability to stop activities deemed imminently dangerous.

Shift Supervisor

Primaryoperationsresponsibility(day to day)

- Supervise and ensure day to day application of Safety/HERA program- Supervise TSF operations.- Provide recommendations for improvement of the tailing operations.- Detect and communicate potential problems related to the tailing operation to upper level management.- Supervise, control and operate the TSF, according to this Operations Manual and related Operations and

Maintenance Manuals.- Supervise, control and operate the TSF reclaim water station according to this Operations Manual and related

Operations and Maintenance Manuals- Supervise, control and operate the TSF tailing pump station according to this Operations Manual and related

Operations and Maintenance Manual prepared by Fluor.

- Recommend emergency tailing diversion or mill shutdown to TailingSuperintendent

- Carryout assigned duties / responsibilities

Cyclone StationOperator

Operation ofcyclone station

- Day to day application of Safety/HERA program- Supervise tailing distribution line operators and cycloned sand placement.- Provide recommendations for improvement of the tailing operations.- Detect and communicate potential problems related to the tailing operation to upper level management.- Supervise, control and operate the TSF cyclone station and scalping cyclone station according to this Operations

Manual and related Operations and Maintenance Manuals.- Provide local site support to operate the TSF reclaim water barges.

Carry out assigned duties / responsibilities

Tailing Deposition Operation /f

- Day to day application of Safety/HERA program- Provide recommendations for improvement of the tailing operations.- Detect and communicate potential problems related to the tailing operation to upper level management Carry out assigned duties / responsibilities


12/217


2.4 TRAINING REQUIREMENTS

The recommended training requirements are summarized in Table 2-2.

TABLE 2-2RECOMMENDED TRAINING REQUIREMENTS

Recommended Training

Position

I n d u c

t i o n

T r a

i n i n g

O p e r a

t i o n s

M a n u a l P

l a n

R e v

i e w

C Q A C l o s e o u

t

R e p o r t R e v

i e w

O p e r a

t i o n s a n

d

M a

i n t e n a n c e

M a n u a l

R e v

i e w

S C A D A a n

d

D C S T r a

i n i n g

E m e r g e n c y

R e s p o n s e

P l a n s

T r a

i n i n g

O c c u p a t

i o n a

l

H e a

l t h a n

d

S a

f e t y T r a

i n i n g

E n v

i r o n m

e n

t a l

T r a

i n i n g

Operations Manager X X

Concentrator Manager X X X X X

ConcentratorSuperintendent X X X X X

Tailing Superintendent X X X X X X X X

Engineering Superintendent X X X X X

EnvironmentalSuperintendent X X X

Maintenance Superintendent X X X X XHealth and SafetySuperintendent X X X X

Control Supervisor X X X X X X X

Cyclone Station Operator X X X X X X

Tailing Deposition SystemOperator X X X X X

Electrical/ MechanicalTechnician X X X X X

Designer (Engineer ofrecord) X X X X

Technical Review Board X X X X


13/217

September 2006Cerro Verde TSF * Operations Manual 7

3.0 FACILITY DESCRIPTION

3.1 BACKGROUND INFORMATION

The Cerro Verde Mine is located in the District of Uchumayo, Province of Arequipa, Department of Arequipa. The Cerro Verde Mine has been in operation since the early 1970s. The current operationconsists of two open pits: Cerro Verde and Santa Rosa, a heap-leach operation, and an SX/EW plantto produce copper cathode. The ore is processed through primary, secondary and tertiary crushers andplaced on a leach pad after agglomeration. The produced copper cathode is loaded into trucks andshipped to the Port of Matarani, some 90 km west from the mine. The general site location is shownin Figure 3-1.

We understand that according to the current mine plans higher-grade leachable material would bedepleted by year 2025. Run of mine (ROM) ore will continue to be stacked until 2035. Sulfidemineralized ore was identified as a result of the exploration programs at the mine. Processing thesulfide ore requires the construction of a concentrating plant and a TSF to store the tailing materialsproduced as a part of the concentration operations.

3.2 FACILITY LOCATION AND BRIEF DESCRIPTION

The TSF site is located approximately 16 km southeast of the town of Arequipa in southern Peru. The TSF will be built in the Quebrada Enlozada immediately north of the processing plant, as is shown onFigure 3-2. The facility will consist of an 85 m high zoned rockfill starter dam, a 260 m highembankment constructed of cycloned tailing sand by the centerline method, and a tailingimpoundment that will cover an area of approximately 453 Ha. The latitude and longitude of theQuebrada Enlozada at the location of the Starter Dam are S16 29 34 and W71 36 20,respectively. The base of the Quebrada Enlozada at the location of the Starter Dam is at anapproximate elevation of 2400 m above mean sea level (amsl). The elevation of the processing plant isabout 2,700 m amsl. The Starter Dam crest elevation will be at 2485 m amsl and the ultimateembankment crest elevation will be 2660 m amsl.

Tailing generated in the flotation process will be sent to two high capacity thickeners that will thickenthe tailing slurry from about 27% solids to about 55% solids by weight. The thickened slurry will beconveyed by gravity through a 48-inch diameter HDPE SDR 21 pipeline to a cyclone station locatedon the right (East) abutment of the tailing embankment. At the cyclone station, the slurry will undergotwo-stage cycloning to separate the sand fraction from the fine fraction. Silty sand (the underflow) willbe used for embankment construction, and the fines (the overflow) will be discharged into theimpoundment.

A reclaim water pond will be maintained at the rear (upstream) end of the impoundment. Water fromthe reclaim water pond will be recycled to the processing plant for reuse and to the cyclone station fordilution. Seepage from the embankment will be collected by a network of finger and blanket drainsand conveyed to a seepage collection sump located immediately downstream of the ultimateembankment toe. The water will then be pumped from the sump to the cyclone station and reused as


14/217


Make-up water to the plant to compensate for the losses at the TSF will be conveyed from Rio Chili via an 11.5 km long freshwater delivery pipeline. Prior to the start-up of the operations, water fromRio Chili will be pumped upstream of the Starter dam to form a start-up water pond. The required

start-up water volume estimated by Fluor is 1,000,000 m3.

3.3 SITE CONDITIONS

The following information describes the local landscape, topography, climatological conditions,seismicity, and site geology.

3.3.1 Landscape and Topography

The Cerro Verde Mine is located on the west slope of the Andes Mountains, in the south segment of what is referred to as the Coastal Batholith. The mine is situated on a plateau that has been eroded anddissected by numerous dry stream valleys to form locally steep and rugged. Elevations in the regionrange from about 2,300 to almost 3,000 m amsl.

3.3.2 Climate and Hydrology

The climate of the area is mild and arid with temperatures fluctuating between 10 and 24C and

average annual precipitation of approximately 36 mm. The rainstorms occur seasonally and aretypically of short duration and high intensity. Over 90% of the annual rainfall is recorded during themonths of January, February and March. The recorded evaporation exceeds the precipitation over 60times. The estimated average annual evaporation rate is about 6.1 mm/day. The humidity ranges fromabout 30% in July to about 70% in February. The prevailing winds in the area are from the northeast.

The region is characterized by distinct microclimate areas. Although located only a few kilometersaway from the mine site, the Rio Chili valley receives significantly more rain than the area of the Cerro

Verde mine. Based on general observations, the rainstorms are usually isolated in small areas, ratherthan covering a larger region. The rainstorms are typically of short duration and high intensity. Thesestorms can cause unexpected floods with large peak flow rates in streambeds that are usually dry. Thefloods may entrain large amounts of sediment and debris and may cause damage to the local roads andinfrastructure

There are several meteorological stations located within about 15 km of the mine site. The coordinatesand years of record of the meteorological stations that are closest to the project site are presented in

Table 3-1.


15/217


TABLE 3-1METEOROLOGICAL STATIONS COORDINATES AND YEARS OF RECORD

COORDINATES

MeteorologicalStation Latitude Longitude Elevation

Data Description and Years ofRecord

Cerro Verde SouthZone 16 32' 23" 71 35' 47" 2688 m 1995 2004 daily data

La Pampilla 16 24' 13" 71 31' 6" 2360 m

1964-1977 max annual 24-hrdata (from KP)

1978-2004 daily data(purchased from Senamhi)

Socabaya 16 28' 71 32' 2339 m 1966-1996 daily data(purchased from Senamhi)

Huasacache* 16 28' 71 33" 2242 1997-2005 daily data(purchased from Senamhi)

*The Huasacache station replaced the Socabaya station in 1997. It was assumed that the Huasacache Station data is partof the Socabaya Station data.

The closest meteorological station is situated immediately south of the Cerro Verde pit and thecollected data is considered to be the most representative of the climate of the area. However, data isavailable only since 1995 and is considered insufficient for hydrological studies. Other meteorologicalstations in the vicinity of the mine include the La Pampilla, Huasacache, and Socabaya stations, whichare regional stations managed by Perus National Weather Service (Senamhi). The Huasacache andSocabaya stations located in the Ro Chili valley are closest to the mine site and have the longestperiod of record (since 1966). The Huasacache and Socabaya stations were used to conduct rainfallfrequency analyses and estimate the probable maximum precipitation (PMP) event for incorporationinto the design and engineering of the TSF. Average precipitation at the Huasacache and Socabayastations over the period of record is approximately 68 mm per year, which is substantially higher thanthat recorded at the Cerro Verde South station and therefore more conservative for the purpose offacility design and management. A summary of the results of the rainfall frequency analysis performedusing the data from the Huasacache and Socabaya stations is presented in Table 3-2. Detaileddescriptions of the analyses are available in Volume 3 PMP and Rainfall Frequency Analyses.

TABLE 3-2MAXIMUM RAINFALLS AT DIFFERENT RETURN PERIODS

Return Period (Year) 24-Hour (mm) 48-Hour (mm) 72-Hour (mm)2 13.3 17.0 20.15 23.7 29.4 36.1

10 30.6 37.7 46.725 39.2 48.1 60.150 45.7 55.8 70.0

100 52.1 63.5 79.8500 66 9 81 2 102 5


16/217


TABLE 3-3PROBABLE MAXIMUM PRECIPITATION

Duration (hour) PMP (mm) Duration (hour) PMP (mm)1 50 30 2652 80 36 2863 100 42 3074 116 48 3245 128 54 3436 138 60 360

12 179 66 37618 215 72 39124 242

The estimated drainage area contributing to the tailing impoundment site is 8.1 km2. The estimatedtotal flood volume of the 72-hour PMP is 2,693,530 m3. The estimated peak Probable MaximumFlood inflow is 95.6 m3/sec. These values will be updated when a longer period of record of the Cerro

Verde South Zone Station becomes available.

3.3.3 Seismicity

The TSF site is located in the Big Bend of the Peru-Chile subduction zone. Since 1471 some 20earthquakes larger than MM (Modified Mercalli) Intensity IX have been recorded in this region.Deterministic and probabilistic seismic hazard evaluations were performed as part of feasibility studiesconducted by URS (URS, 2004). The results of these studies indicated that the design basisearthquake (DBE) would be the maximum credible earthquake (MCE) occurring along the Southernportion of the Peru-Chile subduction zone at a source-to-site distance of about 65 km from the TSFsite. The DBE was specified as a moment magnitude 9.0 (Mw) megathrust earthquake producing apeak horizontal acceleration at the top of bedrock of 0.47g at the TSF site. The selected MCE isassociated with return periods of about 2,000 to 3,000 years. The seismic hazard evaluations

performed by URS were included in Volume 7 Static and Seismic Stability Analyses.3.3.4 Geology

Rocks that outcrop in the region include Precambrian gneiss that is overlain by a sequence of Jurassicto Tertiary age sedimentary units, extrusive volcanic units, and intrusive volcanic and igneous units.

The region has a number of strong structural trends, including a predominant northwest to southeasttrends, as well as east to west and northeast to southwest trends. The northwest trending structuresare predominant at the Cerro Verde Mine, with joint, fault, and geologic contact trends having this

general orientation. The geology of the TSF site consists of a metamorphic basement unit that hasbeen overlain by a sequence of volcanic and sedimentary units that have been subsequently intruded.

The valley bottom beneath the Tailing Embankment site is underlain by coarse dense alluvial outwashcontaining occasional pockets of volcanic ash. A thin veneer of colluvium covers the abutment slopesthough rock outcrops are frequent. A large faulted block Middle Jurassic Limestone referred to as theS i F i b d h L f Ab Thi i li f bl f


17/217


3.4 DESIGN BASIS AND CRITERIA

The general objective of the final design of the TSF was to provide storage for the planned tailing

materials in a safe and environmentally responsible manner. Specific project objectives for theembankment design are to:

Satisfy internationally accepted stability criteria for embankment construction in areas of highseismicity.

Minimize risk of seepage into the environment; aim at achieving zero discharge facility. A zerodischarge facility in this case refers to a TSF and its ancillary facilities designed where necessary

with liners to prevent seepage or with pump back systems to collect potential seepage, so that nocontaminated seepage that can harm the environment is released.

Cost effectively incorporate locally available materials for construction without compromisingsafety.

Satisfy all Peruvian regulatory requirements associated with construction of TSF.

3.4.1 Compliance of Standards and Regulations

The operation of the Cerro Verde TSF should comply with the regulations, standards and guidelinesissued by the Peruvian Ministry of Energy and Mines (MEM), Ministry of Agriculture (MA), Ministryof Health (MH), and the National Environmental Council (CONAM). To assure these standards aresatisfied, an Environmental and Social Management Plan (ESMP) was developed. The PSP ESMP

will be updated periodically throughout the life of the project in order to reflect operational andregulatory changes, to respond to monitoring results and incorporate improvements in environmentalmitigation procedures. The ESMP will be the mandating document for all environmental and socialmanagement, mitigation and monitoring, and should be consulted in conjunction with this TSFOperations manual.

The regulations described in this section are those specifically related to the operation of the TSF,including general regulations applicable to all mining facilities and also specific regulations establishedin the Cerro Verde PSP EIA and ESMP; it is important to note that the environmental monitoringprograms (such as meteorological, biological and geotechnical monitoring), included in the PSP EIAbecome legal obligations applicable to the TSF upon approval of the EIA, in accordance with thePeruvian legal framework.

Water Quality Regulations

The MEM has developed water monitoring guidelines and requirements for monitoring frequency,locations and maximum permissible levels of parameters for designated mine effluent dischargepresented in Ministerial Resolution No. 011-96-EM/VMM (MEM, 1996a). In addition, the MA, inconjunction with the MH have developed water quality guidelines for receiving beneficial use waters


18/217


Class III: Water used to irrigate raw-eaten vegetables and water consumed by animals Class IV: Water in recreational areas with primary contact (public toilets and similar uses) Class V: Water for fishing bivalve shellfishes Class VI: Water in aquatic or native preservation areas and for commercial fishing

The only receiving water body near the project area is the Ro Chili, which is classified as Class III. Asummary of the updated water quality standards for mine effluents and Class III waters are presentedin Table 3-4.


19/217


TABLE 3-4WASTE WATER DISCHARGE AND WATER QUALITY STANDARDS SUMMARY

Parameters UnitsMEM (1)- Regulatory

Maximum PermissibleLevels (MPL) for Mine

Effluents

General Water Law (2) - Per Water

Class III

World BankGuidelines (3)

ANIONS, NUTRIENTS AND GENERAL CHARACTERISTICS

Dissolved oxygen mg/l 3(a)

-(BOD) mg/l 15 -

Nitrate as N mg/l 100 (b) -

Sulfide mg/l -

pH s.u. 6.0 - 9.0 6.0 9.0

TSS mg/l 50 50

Cyanide, total mg/l 1 1

Cyanide, free mg/l 0.1 0.1

Cyanide, WAD mg/l 0.2 0.1 0.5

Hexane extractable oil andgrease mg/l 0.5 10

Fenols mg/l -

METALS (c)

Arsenic mg/l 1 0.2 0.1

Cadmium mg/l 0.05 0.1

Chromium mg/l 1 0.1Copper mg/l 1 0.5 0.5

Iron mg/l 2 3.5

Lead mg/l 0.4 0.1 0.2

Mercury mg/l 0.01 0.01

Nickel mg/l 0.5

Selenium mg/l 0.05 -

Zinc mg/l 3 25 2BACTERIAS

Coliforms, total (d) MPN/100ml 5,000 -

Coliforms, fecal (d) MPN/100ml 1,000 -Notes:(a) Minimum required.

(b) The Maximum Permissible Level (MPL) for Nitrate specified in the General Water Law of Peru is 100 mg/m 3, which is about 1,000 times lower than


20/217


Air Quality Regulations

Air quality monitoring procedures, maximum permissible limits for emissions from mining-

metallurgical activities and air quality standards were regulated by the MEM under MinisterialResolution No. 315-96-EM/VMM (MEM, 1996b). Later, national air quality standards for residentialareas have been established by CONAM under Supreme Decree No. 074-2001-PCM (CONAM,2001) and Supreme Decree N 069-2003-PCM (2003), replacing the MEM MPLs, except for thearsenic, for which the MEMs MPL is still applicable.

A summary of the ambient air quality standards is presented in Table 3-5.

Table 3-5

AIR QUALITY STANDARDS SUMMARY

PM-10 SulfurDioxideCarbon

MonoxideNitrogenDioxide Ozone Arsenic LeadReference Period

(g/m 3)

1 hour - - 30,000 200 (5) - - -

8 hours - - 10,000 - 120 (4) -

24-hours 150 (2) 365 (5) - - - 6 (6) -

Monthly Average - - - - - - 1.5

(3)

NationalStandards

for AirQuality (1)

Annual Average 50 80 - 100 - - 0.5

(7)

Annual Average 100 100 - 100 - - -

World BankGuidelines (8)

24-hours 500 500 - 200 - - -Notes:1 Supreme Decrees No 074-2001-PCM (2001) and N 069-2003-PCM (2003).2 Not to be exceeded more than 3 times a year3 Not to be exceeded more than 4 times a year4 Not to be exceeded more than 24 times a year.5 Not to be exceeded more than1 time a year.6 Resolution No. 315-96-EM/VMM (MEM, 1996b)7 Average of monthly values8 WB Environmental Health and Safety Guidelines, Mining and Milling Open Pit, 1995

Air Emissions Regulations

The maximum permissible limits for emissions from mining-metallurgical activities are regulated bythe MEM under Ministerial Resolution No. 315-96-EM/VMM (MEM, 1996b). These limits wereestablished for PM-10, lead, arsenic and sulfur dioxide. In case of sulfur dioxide, the maximumpermissible limits for emissions are linked to total sulfur input to the process, which is applicable tosmelters.


21/217


Table 3-6AIR EMISSIONS STANDARDS

PM-10Sulfur

Dioxide Lead ArsenicReference

(mg/m 3)MEM

Standards (1) 100 According to

sulfur input 25 25

WB (2) 50 (3) 2,000Notes:(1) MEM, Ministerial Resolution No. 315-96-EM/VMM, 1996(2) WB PPAH, General En ironmental Guidelines, 1998v(3) Particulate Matter (PM)

Groundwater

No maximum allowable standards or limits for groundwater quality have been established in Peru. According to the commitment made by SMCV in the EIA, the established baseline values forgroundwater quality will be statistically compared with the results of the groundwater monitoring. The

methodology and criteria for groundwater monitoring established in the EMP (Appendix A) should befollowed.

Vegetation and Fauna

The Supreme Decree N 034-2004-AG Categorization of Peruvian endangered species of faunaestablishes the list of protected species of fauna, but regulations and guidelines have not beenestablished in Peru for biological monitoring. Therefore, the program for biological monitoringpresented in the EMP (Appendix B) should be followed. The monitoring parameters are focused onboth a qualitative and quantitative analysis of fauna and vegetation.

A qualitative analysis of reptiles and mammals will be performed to establish a confirmed presence ofthese species. A quantitative analysis of birds will be performed to establish the overall abundance(estimated total numbers) of these species. A quantitative and qualitative evaluation of the guanacoand their use of the local habitat in and around the TSF will be performed.

The list of protected species of flora has been established by INRENA (National Institute of Naturalresources), but this regulation does not established monitoring procedures. Therefore, the program for

vegetation monitoring presented in the EMP (Appendix B) should be followed.

Soils

Regulations and guidelines have not been established in Peru for soil quality. The methodology andcriteria to this respect presented in the Cerro Verde PSP ESMP should be followed. The proposed


22/217


Geotechnical Conditions

Regulations and guidelines have not been established in Peru for the control of physical stability and

geotechnical conditions. The monitoring activities to assess the geotechnical conditions of theembankment include piezometer monitoring, seepage monitoring, regular inspections, and plannedgeotechnical investigations. The results of the monitoring will be compared to the assumptions madein evaluating the stability of the embankment (Volume 7 Static and Seismic Stability Analyses), andmitigation measures will be adopted as appropriate (see Section 10 Emergency Response Plan).

3.4.2 International Guidelines

The current international guidelines for environmental management were considered in the

preparation of the environmental monitoring program for the Cerro Verde TSF.

In 2004, the World Bank (the Bank) and the International Finance Corporation (IFC) which is anoperating unit of the World Bank developed and issued what are known as the Equator Principles(IFC, Equator Principles, June 2003). The Equator Principles are implemented through the use of theBanks and IFCs environmental guidelines related to environmental, socioeconomic, and culturalissues developed for the international financial entities. Many mining companies and internationallenders have adopted the Equator Principles as a binding prerequisite for project financing. TheEquator Principles were developed by the Bank and IFC to provide a framework for minimizingpotential environmental and socioeconomic problems that may affect the lenders investment risk ininternational mining projects.

The Equator Principles require mining projects to develop an Environmental Management Plan thatdraws from information contained in a projects Environmental Impact Assessment document. TheEMP is required to address several topics including mitigation measures, monitoring programs, riskmanagement, and environmental management scheduling.

In addition, mining projects must adhere to applicable Safeguard policies and sector-specificenvironmental, health and safety (EHS) guidelines. The specific World Bank and IFC guidelines andstandards that apply to the Cerro Verde mine include:

World Bank Pollution Prevention and Abatement Handbook (PPAH), Base Metal and Iron OreMining, July 1998

World Bank Mining and Milling Open Pit Guidelines (1995) IFC Operational Policy 4.01, Environmental Assessment IFC Operational Policy 4.37, Safety of Dams

3.4.3 Design Basis and Criteria

The design basis and design criteria adopted for the design of the Cerro Verde TSF are presented in Table 3-7 and Table 3-8, respectively.


23/217


TABLE 3-7CERRO VERDE TSF DESIGN BASIS

Site Characteristics Location 16 km ESE of ArequipaElevation 2400-2700 mDesign Max Temperature 30 deg. CDesign Min Temperature 0 deg. C Short occurrences onlyWind (max gust) 100 km/hrPrevailing Wind Direction SW

Average Annual Precipitation 36 mm South Zone Station Average Daily Evaporation 6.1 mm

Catchment Area 810 Ha No diversion channelsPMP 391 mm 72-hrMCE M 9.0

Operating Requirements/Assumptions

Ore type Porphyry Copper

Ore Reserve 1.015 billion metric tons About 870 million tons will be accommodated inthe designed tailing facility. Additional storage

would be required for the remaining ore reserve.

Production Rate 108,000 t/d Ramp-up schedule for 1st 6 monthsTotal Years of Production > 25 365 d/yr, 24 h/dSlurry Percent Solids from Plant 27% Range 26-30%Slurry Flow Rate 14,500 m 3/hPercent Solids from Tailing Thickeners 55% Range 50-60%Percent Fines in Tailing Slurry 67.5% Weighted Average Tailing SampleSlurry Solids SG 2.73 From Flour

Underflow Solids SG 2.7 Lab testOverflow Solids SG 2.73 Lab testSlurry pH 10 Range 9.0 10.5

Average Dry Density of Overflow Varies based on consolidation testing and analysis

Average Compacted Dry Density ofUnderflow 1.58 t/m

398% of max dry density (ASTM D 698);the 1.58 t/m 3 value will vary for different tailingmaterials over the life of the mine.

Start-up Water Requirement 1,000,000 m 3 From Fluor


24/217


TABLE 3-8CERRO VERDE TSF DESIGN CRITERIA

Regulations North America/Peru Meet more stringent regulations when there is no conflictwith Peruvian regulation.

Flood Storage Requirement PMF Contain within impoundment, min 100 m fromembankment crest during flood conditions.

Seismicity/Earthquake Load MCE Canadian Dam Association, Dam Safety Guidelines,1999Min Freeboard (Vertical distance betweenembankment crest and max impoundmentelevation)

3 m To provide sufficient flood storage and accommodateanticipated settlements.

Min Static Factor of Safety (FOS) 1.5 Canadian Dam Association, Dam Safety Guidelines,1999; USBR, Chapter 4, 1987Post-earthquake FOS 1.2 ANCOLD Guidelines, 1998; USBR, Chapter 13, 2001Max Embankment Deformation 3 m To preclude release of fluid from the impoundment.

Seepage/Solution Discharge Requirements Zero DischargeConceptEmbankment drains, sump, cut-off wall, grout curtain,monitoring/pumpback wells, limestone area treatment

Starter Dam Characteristics:Type Zoned rockfillUpstream Slope 2H:1VDownstream Slope (Upper Portion and betweenbenches) 2H:1V Benches will be utilized for access and sand distribution.Downstream Slope (Lower Portion) 3.5H:1VStarter Dam Crest Width 15 mStarter Dam Crest Elevation 2485 m

Embankment Characteristics:

Construction Type Centerline

Construction Material CompactedUnderflow

Maximum Percent Fines in Underflow 15% (Passing No. 200 sieve size)Required Recovery of Underflow 34% Of total tailing stream.Cyclone System Operating Time (min) 90%Maximum Lift Thickness (loose layer) 0.3 m Thickness prior to compactionCompaction Effort/Density 98% 98% of maximum dry density (ASTM D 698)Maximum Embankment Elevation 2660 m Private property restrictionCenterline Downstream Slope 3.5H:1VCrest Width 50 m

Impoundment:

Impoundment Beach Slope 0.50% Assumed beach slopePond Size 20 Ha From Fluor

Pond Location relative to Embankment As far as possiblePond located at upstream end of impoundment, possiblytwo ponds. Pond will be against the starter dam forapproximately 3 months during startup.

Seepage Collection System Characteristics:


25/217


4.0 FACILITY OPERATION

4.1 OBJECTIVE

The objective of this chapter is to describe the significant components of the tailing facility and todefine operating standards and procedures in accordance with the design criteria, regulatoryrequirements, company policies and sound operating practices. The described procedures aim toprovide guidance for safe, economical and environmentally responsible disposal and storage of tailingmaterials.

4.2 TAILING PRODUCTION AND TRANSPORT

4.2.1 Tailing Characteristics and Production Schedule

Run of mine (ROM) ore is hauled from the open pits by trucks and dumped into the primary gyratorycrushers. This crusher reduces the ROM ore from rocks up to 1-2 m in size down to all less than 280mm. Crushed ore is transported by conveyors to an open stockpile adjacent to the concentrator. The50,000 t live capacity of the stockpile allows the secondary and tertiary crushing stages to continueoperating while the primary crusher is being serviced.

The crushed product from the secondary crusher is returned to the coarse ore surge bin so it can bere-screened. Secondary screen undersize is 100% less than 50 mm. The tertiary crushing has fourlines which operate independently of each other, although sharing common feed distribution andproduct conveyors. Each line includes a feed surge bin, a feeder and a high pressure grinding rollcrusher (HPGR). These crushers exert a very high pressure on the ore passing through them. HPGRproduct is transferred to a row of ball mill feed bins. The HPGRs are in closed circuit, with thedownstream ball mill feed screens providing a positive control on maximum particle size to thegrinding circuit. Oversize from these screens returns to the HPGR surge bin for re-crushing. Thereare four independent grinding lines, each consisting of a feed surge bin, two reclaim feeders, two

double deck screens, a sump and cyclone feed pump, a cyclone cluster and a ball mill. Each feederdischarges to a wet screen where the finely crushed ore is slurried and washed, with the fine underflowslurry discharging to the cyclone feed sump. The partly dewatered screen oversize is conveyed back tothe HPGR surge bin. Screen undersize slurry is pumped to the cyclone cluster, which separates thefinished product size material from the oversize. Oversize flows to the ball mill for grinding tofinished size. The ball mill has a variable speed drive to control grind size to a narrow range. Theparticles need to be fine enough for mineral liberation, but coarse enough, so that sufficient sand isavailable to build the tailing embankment. The ball mill product discharges to the same cyclone feedsump as the screen undersize and is pumped to the cyclones for size classification.

Cyclone overflow is sampled and analyzed for size and metal content as it flows to the rougherscavenger flotation row. Each grinding line has a dedicated row of flotation cells to make the initialrecovery of mineral from the ground ore. Rougher concentrate from the first one or two cells in therow is higher grade than concentrate from the later scavenger cells and is handled differently. Therougher concentrate is given a short regrind in a stirred media detritor (polish mill) to clean the


26/217


the cleaner row, referred to as cleaner scavengers, returns to the regrind circuit for further grinding. The residual tailing from the cleaner scavengers is a final reject product and joins the scavenger tailing.

Tailing from flotation represents 98% of the total plant feed weight and must be safely stored inperpetuity. The tailing is initially thickened in two high capacity thickeners to recover approximately60% of the contained water for recycle to the process water system. The remaining thickened solidsat 50-55% density are pumped to a pipe launder for transport to the tailing storage facility (TSF). Thislaunder is at a shallow slope and flows by gravity at atmospheric pressure the pipe is never morethan half full.

The realistic and aggressive start-up production schedules, provided by SMCV that were used as abasis for the material balance and water balance modeling for the TSF (Volume 5 and Volume 6,

respectively), are presented in Table 4-2-1.

TABLE 4-2-1RAMP-UP PRODUCTION RATES

Date Realistic Ramp-Up Schedule Aggressive Ramp-Up Schedule

t/d t/d11/01/2006 27,000 54,00011/08/2006 29,500 54,00011/15/2006 32,500 54,00011/22/2006 36,500 54,00011/29/2006 40,500 54,00012/06/2006 44,500 54,00012/13/2006 48,500 54,00012/20/2006 52,500 108,00012/27/2006 81,000 108,00001/03/2007 84,000 108,00001/10/2007 88,000 108,00001/17/2007 92,500 108,000

01/24/2007 97,000 108,00001/31/2007 101,500 108,00002/07/2007 106,000 108,00002/14/2007 108,000 108,000

Pilot testing on representative ore samples from the Cerro Verde mine was performed by Hazenduring the project feasibility study. The results of the pilot testing included a range of gradationscorresponding to the processing of the different ore samples. SMCV estimated the weighted averageof the gradations of the whole tailing materials planned to be produced by the processing plant, which

was used as a basis for the design. Krebs Engineers (Krebs) performed simulation analyses for theweighted average whole tailing gradation to estimate the quantity and quality of underflow materialsthat can be produced by a range of cyclone arrangements. The estimated weighted average wholetailing particle size distribution and the gradations of the tailing cyclone underflow and overflowestimated by Krebs, are presented in Figure 4-2-1. The presented gradations have been used as a basisfor the design of the tailing facility. If a variation in the characteristics of the produced whole tailing is


27/217


underflow density can range from 50 to 60 percent solids depending on feed rate and orecharacteristics. Higher feed rate will typically result in reduced density. If more that one grinding lineis out of operation, only one thickener would normally be operated for that period.

Refer to the operations manual for Area 3700 for details of tailing thickener operation.

4.2.3 Whole Tailing Pipeline

Following thickening, the tailing slurry will be gravity-fed through a 48-inch HDPE pipe launder to acyclone station located on the east abutment of the tailing embankment. This launder is at a shallowslope and flows by gravity at atmospheric pressure the pipe is never more than half full. There areinspection manholes installed at 500 meter intervals along the length of the launder to allow inspection

of the pipe for wear. If required, vents can also be installed at these manholes. Provision has beenmade for offtakes from the fresh water line adjacent to the tailing launder for potential local flushingof the line.

Refer to the operations manual for Area 3700 for details of tailing launder operation.

4.2.4 Tailing Cycloning

Two cyclone stations will be constructed for the operation of the TSF. The purpose of the firstcyclone station (the Central Cyclone Station) located on the east abutment of the tailing embankmentis to produce tailing sand for the construction of the tailing embankment. The second cyclone station(the Scalping Cyclone Station) will be located at the Concentrator plant site and will come in operationafter the first year of operation of the facility. The purpose of the scalping station is to separate thesand from a portion of the whole tailing stream. The sand would then be combined with theremainder of the tailing feed from the Concentrator and sent to the central cyclone station forsubsequent cycloning. The tailing overflow produced at the scalping station will be used for depositionfrom the upstream ends of the impoundment to facilitate pond management.

The slurry coming through the tailing launder (Section 4.2.3) to the Central Cyclone Station is re-diluted to 39 percent solids prior to gravity feeding to two clusters of first stage cyclones. The firststage cyclones are equipped with an internal wash stage (cyclowash), which helps reduce the amountof fines reporting to the underflow stream. The sand underflow from this first stage is re-diluted andfed by gravity to a single cluster of second stage cyclones. The underflow from this final stage isrigorously controlled by the use of an on-stream particle size analyzer to ensure that the content of

very fine particles remains within limits (


28/217


to cyclone system. Each move will have to be carefully orchestrated to minimize cyclone downtimeand loss of sand production. It may be expeditious to replace much of the equipment and structurerather than moving the existing, just to maintain as much sand production as possible. Duringrelocations, whole tailing will be discharged to the upstream impoundment area. During such periods,some of the whole tailing could be discharged to other fill areas in place of scalping cyclone overflow.

The minimum required cycloned underflow sand for embankment construction versus time for aproduction rate of 108,000 t/d is illustrated in Figure 4-2-2. The sand requirement and whole tailingproduction were adjusted to reflect the realistic start-up production schedule (see Table 4-2-1)provided by SMCV.

Refer to the operations manual for Area 3800 for details of cyclone and solids placement operation.

4.2.5 Jacking Headers

The coarse fraction (underflow) produced at the cyclone station will be used to construct theembankment and the fine fraction (overflow) will be discharged into the impoundment. Theunderflow will be transported from the cyclone station to the embankment via one of two pipelines.Initial operation will be with a 14-inch pipeline to the dam crest connected to a 12-inch pipeline acrossthe starter embankment crest. Once production approaches normal design rates flow will be throughan 18-inch line to the crest connected to 16-inch steel line along the crest. Both lines will initially beconnected to downcomers fitted with spray bars, to distribute the sand across the face at a lowerelevation. These downcomers will be retracted as the discharge level rises until ultimately each line

will have its own spray bars mounted at the pipe. These two pipelines will be placed on a jackingheader along the downstream side of the embankment bench on elevation 2475 m.

The overflow will be transported via two 32-inch pipelines placed on another jacking header along theupstream side of the embankment crest (elevation 2485 m). The configuration and location of thejacking headers in cross section is illustrated in Fluor/PSI drawings PSP108-C-3830-50T-022, 023 and025.

Refer to the operating manual for Area 3800 for design and operating details of the jacking headers.

4.2.6 Other Delivery Lines

The feed launder to the first stage cyclones overflow lines is arranged to allow whole tailing to bypassthe cyclones on an emergency basis and discharge to one of the overflow lines. The other overflowline extends beyond the initial deposition area to the western extremity of the embankment. This will

be used intermittently to deposit overflow solids in the western valley to preclude the development ofa pond in the limestone area.

Second stage cyclone overflow contains a relatively small amount of solids and is discharged through asingle point discharge pipe into the upstream side of the embankment, not far from the cyclonestation. This line also picks up intermittent overflows from all the various tanks, launders, and vessels.

September 2006


29/217


This section presents a description of the TSF embankment and provides guidelines for itsconstruction. The following items are discussed:

Description of TSF embankment Embankment design assumptions Start-up Embankment Construction Contingency measures for embankment construction General embankment construction Deposition on the embankment crest Placement of underflow sands over the drains

Description of special embankment features Deposition of underflow sands into the Eastern Quebrada Description of embankment instrumentation Embankment construction schedule Quality control and assurance of embankment construction

4.3.1 Description of the Embankment

The tailing embankment will consist of an approximately 260 m high (at maximum height)embankment constructed of cycloned tailing sand by the centerline method over an 85 m high zonedrockfill Starter Dam. The embankment is underlain by an extensive drain system to promote rapiddrainage of the cycloned tailing sands. The Starter Dam, and the drain system within the estimatedembankment limits for the first two years of operation are being built prior to the start of theoperation of the concentrator plant. The embankment will be raised in lifts of cycloned tailing sandsconcurrent with filling the impoundment. A minimum of 3 m of freeboard between the embankmentcrest elevation and the elevation of the impounded tailing will be maintained at all times. As theembankment is raised in height, its footprint will expand downstream. Accordingly, the embankment

underdrain system will be expanded. A brief description of the Starter Dam and the tailingembankment follows.

Starter Dam : The purpose of the Starter Dam is to provide storage for the tailing overflow and whole tailing materials to be impounded during approximately the first year of operation as theembankment is being constructed of cycloned tailing underflow sand. The required height of theStarter Dam was established in an iterative process during the feasibility design of the tailingfacility (URS, Tailing Embankment Feasibility Design, 2004). The suggested Starter Dam crestelevation of 2485 m was verified during the final design of the facility (Volume 5 MaterialBalance Analysis).

The configuration and brief descriptions of the various zones of the Starter Dam are presented inFigure 4-3-1. The upstream slope of the Starter Dam is 2H:1V, and the downstream slope variesfrom 2H:1V to 3.5H:1V. There will be an 8 m and a 15 m wide bench at elevation 2455 m and2475 m respectively along the downstream slope The purpose of the benches and the flatter

September 2006


30/217


The construction of the Starter Dam is scheduled to be completed in August 2006. The constructionof the tailing underflow embankment is scheduled to begin on November 1, 2006 immediatelyfollowing the commissioning of the processing plant.

4.3.2 Embankment Design Assumptions

The design of the embankment was performed following the design basis and design criteria presentedin Table 3-6 and Table 3-7, respectively. Details on the assumptions and data used for theembankment design are presented in Volume 5 Material Balance Analysis. A summary of the mainassumptions for the embankment design is given below:

Whole Tailing Production Rate (dry metric tons)= 108,000 t/d

Underflow Production (dry metric tons)= 33,048 t/d (34% recovery at 90% cyclone stationavailability)

Minimum Freeboard = 3 m*Freeboard is defined as the vertical distance between the embankment crest and the maximumlevel of the impounded tailing.

Embankment Slope = 3.5H:1V Embankment Crest Width = 50 m

Underflow Percent Solids(by weight) = 70%

Maximum Percent Fines of the Underflow(particles smaller than 75 micron)= 15%

Compacted Dry Density = 98% of maximum dry density per ASTM D 698 (estimated 1.58 t/m 3 based on testing during design)

Maximum Lift Thickness (for compaction of embankment sands) = 30 cm (loose prior tocompaction)

4.3.3 Start-up Construction

Embankment construction during start-up is critical to TSF performance from a material balance and

stability standpoint. The start-up construction covers the period of time until the sand embankmentreaches elevation 2485 m at 3.5H:1V downstream slope.

Embankment Construction during Start-Up

The tailing embankment will be constructed of compacted underflow tailing materials and raised by

September 2006


31/217

pCerro Verde TSF * Operations Manual 25

To allow for the three steps to occur at the same time, the embankment will be divided into aminimum of three approximately 200 m long sections. The longitudinal length of the Starter Dam atelevation 2435 m is approximately 600 m and will allow the division into three zones. Thedownstream slope of the Starter Dam from the toe to elevation 2435 m was intentionally selected as3.5H:1V to facilitate the initial placement of the underflow materials to the desired slope. Theproposed sequence for the start-up embankment construction is as follows:

A 12-inch HDPE underflow delivery line will be placed on a jacking header system on the StarterDam bench at elevation 2475 m. This delivery line will be needed for the first two months whenthe mill production rate is about 54,000 tons/day. Subsequent to that time, the production rate

will increase to 108,000 tons/day and a 16-inch underflow delivery line will be used.

Pipe extensions (6) with a spray bar (4) will be attached to the delivery line and extended toabout elevation 2435 m along the slope (Figure 4-3-3a).

Underflow tailing deposition will take place along a segment of about 200 m length. After a layerof approximately 0.3 m loose thickness has been placed, deposition will progress to the next 200m long segment. If deposition progresses from East to West, the most eastern open valve will beclosed and the subsequent new valve following the last open valve (on the west) will be opened.

This procedure will be repeated until all previously operated valves are closed and the valves onthe next section for deposition are opened.

It was assumed that each of the three steps of the embankment construction would take about 24hours. Thus, while depositing into the second segment, the first segment will drain, and whiledepositing in the third segment, the first segment will be compacted and the second segment willdrain. Construction of two layers to elevation 2435 m is planned to take approximately 6 days(Figure 4-3-3a).

Over the following 2 to 3 months the spray bar extensions off the delivery pipe will be gradually

withdrawn towards the bench at elevation 2455 m as the embankment elevation rises (Figure 4-3-3b).

Pipe extensions with spray bars from the delivery line on the header will be used until theembankment elevation approaches elevation 2475 m and an uniform 3.5H:1V slope has beenestablished (Figure 4-3-3c).

The underflow deposition will continue by discharging from spigots in the delivery line on the

jacking header at 2 m intervals (Figure 4-3-3d). Deposition will take place over about 200 mlength along the crest at a time.

The header will be raised as required to provide sufficient space (underneath) for compaction ofthe deposited underflow along the crest of the embankment. A minimum of 4.5 m clearancebeneath the header is required.

September 2006


32/217

Cerro Verde TSF * Operations Manual 26

the achieved lift compaction (homogeneous throughout the lift thickness at a minimum of 98% ofthe maximum dry density per ASTM D 698).

Due to the limited initial bench width, and the fast embankment and header raise rate, hydraulicdeposition of the underflow on the bench is expected to be difficult, so careful planning will beessential. The embankment crest between elevation 2475 and 2485 m should be raised bydepositing underflow from the upstream spray bars and by dozing previously drained underflowupstream from piles that may form immediately downstream of the jacking header (along the edgeof the embankment slope). Dozing and compacting the drained underflow is expected to increasethe rate of lift construction. Beyond elevation 2485 m, the embankment crest will be raisedfollowing the procedure described in Section 4.3.5.

Underflow Stockpiling during Start-up

At the beginning of the embankment construction, the area available for deposition of underflow willbe limited to the area of the downstream slope of the Starter Dam. This limited area will restrict theamount of underflow that can be deposited. The start-up embankment construction sequence and thearea limitations during the first several months of the embankment construction are discussed in

Volume 5 Material Balance Analysis.

It is estimated that during the first 4 to 6 months of operation, the amount of underflow that can beplaced and compacted on the embankment is equivalent to 70 to 80 percent cyclone operating time.

Two alternatives are available: 1) adjust the cyclone operating time to produce only the underflowquantities required for embankment construction and discharge the remainder of the tailing flow intothe impoundment, and 2) produce as much underflow as possible and stockpile it downstream of theembankment toe. Alternative 2 above should be adopted to the extent feasible. Implementing thisapproach will have a positive effect on the material balance during this critical part of the embankmentconstruction. Some quantities of underflow will be required for mechanical placement over the drains(Section 4.3.7) and the stockpiled underflow quantities could be used for this purpose. Stockpiledunderflow can also be used as contingency for embankment construction during periods when thecyclone station is not in operation. All stockpiled material should be utilized for construction byhauling it to the place of final use, spreading it in 30-cm lifts and compacting it to 98% of maximumdry density (ASTM D 698). Stockpiled underflow material should not remain in uncompacted state inthe stockpile area or elsewhere, as this would create a potentially liquefaction susceptible zone in theembankment.

It is planned to stockpile the extra underflow from a ridge downstream of the Starter Dam toe onthe east side of the valley (Figure 4-3-8). The underflow will be discharged via a 12 HDPE pipe off

the main header. The underflow slurry would discharge into a pit excavated in bedrock for energydissipation. The stockpiled underflow would be allowed to drain and would be mechanicallytransported and placed where required.

By the time the underflow elevation reaches the elevation of the Starter Dam, it is anticipated thatthere will be no restriction on the amount of underflow that can be deposited (at 108,000 t/d

September 2006


33/217

Cerro Verde TSF * Operations Manual 27

presented in Table 4-3-1. According to the plan, the start-up water pond elevation will beapproximately 2431.34 m and will store approximately 1.9 million cubic meters of water.

TABLE 4-3-1PROYECTO CERRO VERDE - PRESA DE RELAVES

DAILY WATER VOLUME AND FLOW RATE FOR START-UP WATER FILL PLAN Daily Water

VolumeEast

Drainage(m ) (1)3

WaterElev. EastDrainage

(m) (2)

Daily WaterVolume

WestDrainage(m ) (3)3

WaterElev. WestDrainage

(m) (4)

3

DailyWater

Volumeone pond(m ) (6)3

WaterElev.OnePond

(m) (7)

Total DailyWater

Volume(m 3)

(1)+(3)+(6) 3

AverageDaily WaterFlow Rate(Liter/sec)

7-Jul 1,926.01 1,926.01

Date Total DailyWater

VolumeEast +West

Drainage(m )

(1)+(3)

TotalCumulative

WaterVolume

(m )

2,412.0 1,926.01 1,926.01 22.29

8-Jul 2,487.04 2,413.0 2,487.04 2,487.04 4,413.04 28.79

9-Jul 4,145.18 2,414.0 4,145.18 4,145.18 8,558.22

10-Jul 6,215.12 6,215.12 71.93

2,415.3 2,609.93 17,383.28

12-Jul 2,609.93 2,609.93 19,993.21 30.21

2,609.93 2,415.9 2,609.93

14-Jul 8,259.37 2,410.0 11,510.95 11,510.95 34,114.08 133.23

15-Jul 3,572.41 2,416.5 13,916.61 161.07

3,572.41 2,416.8 18,105.56 2,412.0 21,677.97 21,677.97 69,708.66 250.9017-Jul 6,587.19 2,417.1 28,216.88 326.58

vol 9 - operations manual complete.pdf

Documents