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Sociedad Minera Cerro Verde S.A.A.

Primary Sulfide Project

Project No. PSP108

Process Description ControlPhilosophy

Specification No. C-OT-25-001Rev. B

22 Apri l 2005


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Client Name: Sociedad Minera Cerro Verde S.A.A. Specif ication C-OT-25-001

Project Name: Primary Sulfide Project Page 1 of 48Project Number: PSP108 Rev. B

FLUOR

Mining & Minerals

PROCESS DESCRIPTION CONTROL PHILOSOPHY


PROCESS

This document has been revised as indicated below. Changes after revision 0 are identified by vertical bars at the

right side of the page, with additions being underlined. Please replace all pages of this specification and destroythe superceded copies. English is the prevailing language of this document.

RevNo.

Originator(name/initials)

RevDate

Revision Descripti on

B K. Wood 22Apr05 Issued for Review

New Issue ; Entire Specification Re-issued

APPROVALS ORIGINAL SIGNED BY

FLUOR DATE CLIENT DATE

Project Manager:

Engineering Manager: Brad Matthews 22Apr05

Area Project Engineer: Brad Matthews 22Apr05

Lead Discipline Engineer: Ken Wood 22Apr05

Process Approval:


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Table of Contents

1. GENERAL DESCRIPTION AND SCOPE...................................................................................................... 41.1 Summary......................................................................................................................................................4 1.2 Definitions ....................................................................................................................................................51.3 General Control Systems Design Criteria....................................................................................................62. CRUSHING..................................................................................................................................................... 62.1 Process Overview........................................................................................................................................62.2 System Interlocks.........................................................................................................................................72.3 Primary Crusher...........................................................................................................................................72.4 Conveyors and Stockpile.............................................................................................................................92.5 Primary Crusher Control Station................................................................................................................102.6 Coarse Ore Reclaim...................................................................................................................................102.7 Secondary Crushing and Screening..........................................................................................................122.8 Tertiary Crushing........................................................................................................................................173. GRINDING ....................................................................................................................................................203.1 Process Overview......................................................................................................................................203.2 Ball Mill Screen and Feeders .....................................................................................................................213.3 Ball Mills and Cyclones..............................................................................................................................213.4 System Interlocks.......................................................................................................................................233.5 Ball Mill Grinding Ball Addition...................................................................................................................244. FLOTATION ................................................................................................................................................. 254.1 Process Overview......................................................................................................................................254.2 System Interlocks.......................................................................................................................................274.3 Rougher and Scavenger Flotation.............................................................................................................274.4 Rougher Concentrate Polishing.................................................................................................................294.5 Scavenger Concentrate Regrind and Classification..................................................................................314.6 Column Flotation........................................................................................................................................334.7 First Cleaner and Cleaner-Scavenger Flotation ........................................................................................355. MOLYBDENUM RECOVERY...................................................................................................................... 365.1 Process Overview......................................................................................................................................365.2 System Interlocks.......................................................................................................................................385.3 Rougher and Scavenger Flotation.............................................................................................................385.4 First Cleaner Flotation................................................................................................................................405.5 Cleaner Scavenger Flotation .....................................................................................................................405.6 Column Flotation........................................................................................................................................425.7 Molybdenum Concentrate Dewatering and Packaging .............................................................................44


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6. CONCENTRATE THICKENING, FILTRATION, STORAGE AND LOADOUT..........................................456.1

Process Overview......................................................................................................................................45

6.2 System Interlocks.......................................................................................................................................466.3 Concentrate Thickening.............................................................................................................................466.4 Concentrate Storage and Dewatering .......................................................................................................476.5 Concentrate Storage and Loadout.............................................................................................................486.6 Concentrate Recycle Water.......................................................................................................................48


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1. GENERAL DESCRIPTION AND SCOPE

1.1 Summary

A. Scope of Specification

The purpose of the Process Control Philosophy is to serve as a basis for the Piping andInstrumentation Diagrams (P&IDs) design and to provide the Control System Design Engineerswith a basis for Instrumentation and Control Systems design.

1. Major items of process equipment are discussed. Items that operate independently of theprocess (e.g., air compressors and power generation) are not included in this document.

2. Process sampling that impacts the control philosophy is included. Reference specificationC-SP-25-003 for specific sampling systems design information.

3. It is not the purpose of this document to discuss the control systems and instrumentationused in this plant. Reference the Instrumentation Design Criteria (C-SP-70-001) and otherrelated specifications listed below.

4. Where there are multiple process lines operating in parallel, only a single line will bediscussed.

B. Related Specifications

C-DC-25-001 Process Design Criteria

C-DC-65-001 Electrical Design Criteria

C-DC-70-001 Instrumentation Design Criteria

C-SP-25-003 Plant Sampling Philosophy

C-SP-55-024 On-Stream Analyzer C-SP-55-027 Particle Size Analyzer

C-SP-70-002 Distributed Control System (DCS)

C-SP-70-003 Programmable Logic Control (PLC) System

C. Control Rooms

There will be one main Concentrator Central Control Room (CCCR) located in the grinding area,with a number of field-hardened HMI operator control stations in outlying areas to interface tothe DCS. These include:

1. Primary Crushing Control Station (PCCS)

2. Fine Crushing Control Station (FCCS)

3. Copper Concentrate Dewatering Station (CCDS)

4. Moly Plant Control Station (MPCS)

Control stations will operate independently of each other and will normally only controlequipment within the specific control station jurisdiction. However, each station will have accessto all status information throughout the system. All areas will be controllable from theconcentrator central control room.


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1.2 Definitions

This process control philosophy, and control logic shown on P&IDs, will use the following definitionsfor control and interlocking of equipment:

A. Start: A start signal is a pulsed signal to start a piece of equipment (pulse 0 to 1).

B. Stop: A stop signal is a pulsed signal to stop a piece of equipment (pulse 1 to 0).

C. Local: Local control is defined as control at the piece of equipment or the equipmentcontrol panel.

D. Remote: Remote control is defined as control distant from the piece of equipment. Forexample, control room operations are always remote to the equipment.

E. Permissive: A permissive signal is used to allow the starting of a piece of equipment.

However, once the equipment is started the permissive signal will not stop it.

F. Trip: A trip signal will stop and/or disallow the starting of a piece of equipment. Thetrip signal will not allow a restart of equipment until the trip condition hascleared.

G. Critical Safety Trip (CST):

A critical safety trip is one which is required to provide personnel protection or preventcatastrophic equipment failure. These trips will be hardwired (or in the case of motors behandled via the motor protection relay). Signal wiring will be fail-safe.

H. Non-critical Trip (NCT):

A non-critical trip is one which is required from an operational standpoint and for generalequipment protection. These trips will be handled via software. Signal wiring will be fail-safe.

The trips of major process equipment types will be handled as follows in general:

Conveyors: Pull cord CSTSpeed switch NCTLevel switch NCTMisalignment switch NCTBelt rip switch NCTBelt slip NCTMetal Detect NCT

Motors: Motor winding

temp

CST

Motor bearing temp CSTOverload current CSTGround Fault CSTEmergency stops CSTMotor Vibration CST

I. Interlock: An interlock is a trip signal which is passed between systems (or pieces ofequipment) to ensure that the systems (or equipment) operate together in a safemanner (e.g., coarse ore conveyor C-3120-CV-002 not running is an interlock


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signal for the coarse ore transfer conveyor C-3120-CV-001). Where criticalinterlock signals are passed between control processors they will be hardwired.

No critical interlock signals will be transferred between PLCs via DH+or DCSgateway communications to avoid spurious trips. All safety switches like pullcords and emergency stops will be hard wired.

1.3 General Control Systems Design Criteria

A. The control system will be designed such that local control will always be available and that theoperator within the control room will have continuous process monitoring, control andemergency shutdown capability. Local and remote stops will always be available. Remote/localselector switches, when required, will be located in the DCS system.

B. The control system will include a Distributed Control System (DCS) to provide overall processmonitoring and control. The DCS system will be overlain by a Knowledgescape high level controlsystem for application of control strategies. Programmable Logic Controller (PLC) based controlsystems will be used for motor control and simple process control. Some major mechanicalvendor packages (e.g. crushers, ball mills and concentrate filters) will contain their own PLCcontrol systems, supplied by the vendors. In these cases, the equipments own PLC will controlall items related to the piece of equipment.

C. All alarm and trip circuitry from field or local panel mounted contacts will be based on fail-safeactivation. Alarm and trip contacts will open on abnormal or fault condition.

D. Electrical shutdown systems, relays and solenoid activated devices or valves, will be de-energized for shutdown. Dual acting solenoid valves shall be energized to open and energizesthe other solenoid to close. Shutdown initiation will be independent of any analog transmitter orcontrol loop and will be from direct connected, dedicated switches wherever possible. Processequipment shutdowns will be implemented directly via the DCS or PLC controlling that part of

the process. If equipment shutdown occurs due to loss of power/power failure, the equipmentwill return to a de-energized state and will not automatically return to a running state uponrestoration of power.

E. All slurry pump gland seal water low flow switches will alarm only and not trip the respectiveslurry pump unless specifically mentioned in this document or shown as such on the P&IDs.

F. The status of each piece of equipment including run/stop/local/remote is displayed on the DCSscreen. A permissive light advises the operators if the equipment is available to start. Permissivelight is not indicated for any piece of equipment unless all equipment in logical sequence tooperate that part of process is ready to be started.

G. Refer to specification Instrumentation Design Criteria C-DC-70-001 for further details.

2. CRUSHING

2.1 Process Overview

A. Ore from the mining operations is dumped, by 218 t haul trucks, into a single dump pocket with a500 t live capacity, which feeds into the top of the primary crusher (C-3110-CR-001).

B. The Primary crusher (C-3110-CR-001) discharges the crushed ore to a 500 t discharge pocketbelow the crusher. Crushed ore is withdrawn from the discharge pocket via a primary crusherdischarge cute (C-3110-ST-001) by a variable speed apron feeder (C-3110-FE-001), which


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discharges to the coarse ore transfer conveyor (C-3120-CV-001). A fixed magnet (C-3110-MA-001) is mounted on a monorail at the discharge of the apron feeder. The conveyor is equipped

with a belt scale (C-3120-SL-001). The transfer conveyor dumps the ore onto the overlandcoarse ore conveyor (C-3120-CV-002). This conveyor is equipped with metal detector ondetection to stop the conveyor (C-3120-MD-001) and a belt rip detection system (C-3120-ZE-002) and feeds the coarse ore stockpile.

C. A sump pump (C-3110-PP-001) in the crushing area can be started and stopped from PCCSand CCCR as needed. The pump can also be operated automatically based on sump level.

2.2 System Interlocks

A. The crushing and ore conveying systems are interlocked to ensure that upstream equipmentstops whenever downstream equipment trips. All conveyors, in general, will be provided with thefollowing trips:

1. Pull-cord (CST)2. Belt misalignment (NCT)

3. Low-speed (NCT)

4. Discharge Chute Plugged (NCT)

B. All belt misalignment switches have two contacts. The first contact provides an alarm in PCCSand CCCR, the second contact shuts down the conveyor. The contacts will be separated suchthat the second contact will be installed close to the limit where the belt touches the steel.

C. The pull cord switches have two contacts as well. One is hard wired to the starter and thesecond one is wired to the DCS to indicate which one of the switches has been pulled.

D. A warning horn will sound for 15 seconds prior to the starting of any conveyor or feeder and, forthe coarse ore conveyor (C-3120-CV-002), will continue during the entire startup sequence. Allequipment in this section is controlled remotely from the PCCS. Local control is also available.

2.3 Primary Crusher

A. The primary crusher will be operated from the primary crusher control station (PCCS) locatedbehind the dump pocket. The dump pocket is designed for two side dumping, two trucks can beparked for dumping simultaneously. Traffic lights are provided for both dump stations andoperated manually by the primary crusher operator. Red light designates a No Dump conditionand green light indicates Dump Allowed condition.

B. The dump station traffic lights will automatically turn red and sound siren Long Horn blast oncondition which causes the crusher to stop. The lights will also turn red and sound siren on the

following:1. Manual selection by operator (NCT)

2. High discharge pocket level (NCT)

3. Coarse ore conveyor tripped (C-3110-CV-002) (NCT)

4. Coarse ore transfer conveyor (C-3120-CV-001) stopped (NCT)

5. Apron feeder (C-3110-FE-001) stopped (NCT)


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C. The crusher drive controls will turn the traffic lights red and sound the horn on the following:

1. Lubrication oil filter differential pressure (to protect against dirty filters) (NCT)2. Hydroset oil filter differential pressure (NCT)

3. Spider grease pump malfunction (NCT)

D. The traffic lights will not turn green before the condition is cleared.

E. To alert the drivers of traffic light changes, the PCCS operator will be able to manually sound thehorn within the PCCS.

F. The primary crusher will be equipped with a rock breaker, (C-3110-RB-001) which will normallybe operated remotely from its control panel in the PCCS or locally via a plug-in waist controlunit.

G. Two SPLIT system cameras monitor the truck dumping and provide an estimate about thecrusher feed particle size distribution (31AI-0113/0114). The estimate is used to provide feedback to the mining department for the control of drilling and blasting and to assist optimizing theperformance of the crushing and grinding circuits. A SPLIT system camera is also installed onthe coarse ore transfer conveyor (31AI-0611) to estimate the crusher discharge particle sizedistribution. The crusher operator manually adjusts the crusher hydroset setting to providemaximum crushing action while maintaining the required crusher throughput rate. Microwavedetectors (31XE-0113/0114) are mounted at the truck dump station which detect when a truck isdumping. The signal is used by the SPLIT system to indicate when the particle size analysis canbe performed.

H. An ADS system at the crusher feed chute is manually operated by the PCCS operator.

I. Local control panels will also be available for the crusher lubrication unit.

J. The crusher drive will be provided with electrical and lubrication system protective trips including:

1. Lubrication oil flow (NCT)

2. Lubrication oil temperature (NCT)

3. Lubrication oil pressure (NCT)

4. High motor power draw (CST)

5. High motor winding temperature (CST)

6. High motor bearing temperature (CST)

7. The following process trips are included

8. High-High discharge pocket level (NCT)

9. Emergency stop (CST)

K. A warning horn will sound for 15 seconds prior to the starting of the crusher. Six (6) hardwiredemergency stop push-buttons will be provided for the crusher and will be located in the PCCSand in the field in locations surrounding the crusher.


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2.4 Conveyors and Stockpile

A. A variable speed apron feeder (C-3110-FE-001) equipped with a hydraulic drive withdrawsmaterial from the crusher discharge pocket and feeds onto the coarse ore transfer conveyor (C-3120-CV-001). The feeder is equipped with a fixed magnet at the discharge end (C-3110-MA-001) to remove tramp steel. The apron feeder speed is controlled by an operator specified setpoint either from the control room or from the local control panel (31SIC-0411). The operator canmanually set the speed of the feeder to avoid discharging the crusher product onto an emptyfeeder and, at the same time, avoiding filling up the surge pocket under the primary crusher. Thefeeder speed can also be controlled automatically based on the surge pocket level or by theexpert system. The apron feeder is provided with electrical and hydraulic system protective tripsto stop the feeder. The feeder is also provided with the following trips:

1. Plugged apron feeder discharge chute (C-3110-ST-002) (NCT)

2. Transfer conveyor (C-3120-CV-001) stopped (NCT)

3. Plugged transfer conveyor (C-3120-CV-001) discharge chute (NCT)

4. Coarse ore stockpile conveyor (C-3120-CV-002) stopped (NCT)

5. Low-low discharge pocket level (NCT)

6. Magnet not energized (NCT)

7. Pull cords (CST)

8. High-high coarse ore stockpile level (31LAHH-0748) (NCT)

B. The coarse ore transfer conveyor belt scale (C-3120-SL-001) monitors, records, and totalizesthe weight of material feeding the mill coarse ore stockpile and displays the results in both thePCCS and the CCCR (31WIC-0606). The weight scale can also be used to provide a set point to

the apron feeder speed. This conveyor is also equipped with a metal detector (C-3120-MD-001)which trips the conveyor upon detection of metal on the belt. A SPLIT system camera (31AI-0611) monitors the primary crusher discharge particle size distribution.

C. The coarse ore transfer conveyor (C-3120-SL-001) discharges onto the fixed-speed coarse ore(stockpile feed) conveyor (C-3120-CV-002). The stockpile will be installed with level profilinginstrumentation to monitor the level in the two dead zones and one zones of the stockpile. Thedrive units for the coarse ore (stockpile feed) conveyor are equipped with a gearbox lubricationunit.

D. In addition to electrical and drive system protective trips, the coarse ore transfer conveyor (C-3120-SL-001) is tripped on the following:

1. High-high discharge cute level (31LAHH0619) (NCT)

2. High-high pulley bearing temperature (31TAHH-0601/0602) (NCT)

3. Coarse ore conveyor (C-3120-CV-002) tripped (NCT)

4. Metal Detected (31NA-0617) (NCT)

5. Belt tear (31XA-0618) (NCT)

6. Belt side travel (31ZA-0608/0609)


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E. When the coarse ore transfer conveyor trips, the apron feeder (C-3110-FE-001) is also trippedand the traffic lights turned red.

F. In addition to electrical and drive system protective trips, the stockpile feed conveyor (C-3120-CV-002) is tripped on the following:

1. Ripped-belt (31XS-00618) (NCT)

2. High-high pulley bearing temperature (31TAHH-0703/0702) (NCT)

3. Belt side travel (31XA-0704/0709) (NCT)

G. When the stockpile feed conveyor trips, the coarse ore transfer conveyor (C-3120-SL-001) andapron feeder (C-3110-FE-001) will stop and the traffic light will be turned red.

H. The coarse ore (stockpile feed) conveyor (C-3120-CV-002) will not stop on High-high coarse orestock pile level. Instead, an alarm will sound in the PCCS and the apron feeder (C-3110-FE-001)

will stop feeding ore to the coarse ore transfer (C-3120-CV-001). The coarse ore conveyor willthen completely discharge all ore on its belt before stopping

I. In general, a bulldozer will be used for stockpile management during extended primary crushershutdowns. When bulldozers are required on the stockpile, a mechanical lockout of the coarseore conveyor will be used.

2.5 Primary Crusher Control Station

A. The primary crusher control station (PCCS) will be located behind the crusher dump pocket,between the two dump points, and will provide a central monitoring and control point for theentire coarse ore crushing, conveying and stockpiling system. The control station will have twographical displays ergonomically designed for one operator. All system alarms will beannunciated on the operator console. A color printer will be provided for shift reporting and

display printouts.

B. A dust suppression system will be provided in the crusher discharge pocket and at each oretransfer point. The dust suppression system will be controlled by the operators located in thePCCS. Dust suppression failure or shutdown will alarm in the PCCS. There will be a dedicatedmaintenance worker assigned specifically and exclusively to daily maintenance of the ADSsystems in the plant, including the primary crushing area. The ADS system is interlocked toequipment in the area. ADS system C-3120-DC-005 requires booster water pump C-3100-PP-002 operating to provide adequate pressure for the system on the top of the coarse orestockpile. The operation of the pump is interlocked into the coarse ore conveyor (C-3120-CV-001.

C. The following information will also be available in the concentrator central control room (CCCR):

1. Status of crusher, feeder, sump pump and conveyors

2. Stockpile levels

3. Coarse ore transfer conveyor weigh scale readout

2.6 Coarse Ore Reclaim

A. Ore is reclaimed from the stockpile by four variable speed, hydraulically operated apron feeders(C-3210-FE-011/012/013/014) into coarse ore surge bins (C-3220-BN-021/022/032/024) viacoarse ore reclaim conveyor (C-3210-CV-003) and coarse ore tripper conveyor (C-3210-CV-


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014). The reclaim conveyor is equipped with a belt scale (32-WI-0208) to measure and controlthe bin feed rate. The coarse ore is discharged from the coarse ore tripper conveyor with a

coarse ore surge bin tripper (C-3210-TR-003), which distributes the ore into the bins. The coarseore surge bins are equipped with dedicated dust controllers (C-3220-DC-061/062/063/064).

B. A self cleaning belt magnet (C-3210-MA-003) is installed above the coarse ore reclaimconveyor, which discharges the tramp metal into a tramp metal bin (C-3210-BN-011). A metaldetector (32NS-0228) is installed on the conveyor after the magnet to stop the belt for detectedmetal.

C. The coarse ore reclaim conveyor cannot be started unless all dust control fans are running. Ifany of the dust control fans is stopped during operations, the apron feeders are stopped aftertime delay.

D. Ordinarily the all bins are being filled with the tripper car system on continuous bases. TheCCCR operator can bypass a bin manually from the DCS system. If a bin is bypassed, itsdedicated dust control fan can be shut down for maintenance purposes while leaving the rest ofthe coarse ore reclaim system running.

E. The coarse ore surge bins are equipped with level meters. The tripper car is automaticallycontrolled to provide more feed into those bins which have lower than average level.Respectively the bins which are full do not receive feed until the level in the bin is decreased to apredetermined level. Proximity switches mounted at each bin indicates the tripper car position.End travel switch stops the tripper car moving if it moves pass all bins.

F. Feed blending control is assisted by the SPLIT system cameras installed on the apron feeders(31AI-0104/0114/0124/0134) assisted.

G. The apron feeders are provided with electrical and hydraulic system protective trips which stopthe feeders. The apron feeders are also equipped with the following trips:

1. Plugged apron feeder discharge chute (C-3110-ST-019/020/021/022) (32LAHH-0103/0118/0128/0138) (NCT)

2. Coarse ore reclaim conveyor (C-3210-CV-003) stopped (NCT)

3. Coarse ore tripper conveyor (C-3210-CV-014) stopped (NCT)

4. Low stockpile discharge chute level (C-3210-ST-011/012/013/014) (32LAL-0101/0111/0121/0131) (NCT)

5. High-high coarse ore surge bin level (C-3230-BN-021/022/023/024) (all bins at the sametime) (32LAH-0427/0527/0627/0727) (NCT)

6. ADS system trip (C-3210-DC-011/012/013/014) (NCT)

7. Pull cords (CST)

8. Dust control fans tripped (C-3220-FA-061/062/062/0640) (after time delay) (NCT)

H. In addition to electrical and drive system protective trips, the coarse ore reclaim conveyor (C-3210-CV-003) is provided with the following protective trips:

1. Magnet not energized or stopped (NCT)

2. Tripper car discharge chute plugged (32LAH-0331) (NCT)


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4. Belt tear (32XA-0212) (NCT)5. Coarse ore reclaim conveyor discharge cute plugged (32LAHH-0211) (NCT)

6. High-high pulley temperature (32TAHH-0201/0202)

7. Pull cords (CST)

8. Belt side travel (32XA-0203/0204) (NCT)

I. In addition to electrical and drive system protective trips, the coarse ore tripper conveyor (C-3210-CV-014) is provided with the following protective trips:

1. Tripper car discharge chute plugged (32LAH-0331) (NCT)

2. Coarse ore tripper (C-3210-TR-023) stopped (NCT)


4. High-high pulley temperature (32TAHH-0301/0302) (NCT)

5. Coarse ore reclaim conveyor discharge cute plugged (32LAHH-0211) (NCT)

6. Pull cords (CST)

J. The high-high coarse ore bin level (all at one time) does not trip the conveyors but trips theapron feeders instead. The conveyor is then allowed to empty itself into the bins. The tripper caris programmed to bypass an individual surge bin, if it is full, while still providing feed to the emptybins.

K. ADS dust suppression system is provided at each apron feeder feed and discharge chute aswell as in the secondary crusher product transfer conveyor transfer chute (C-3220-ST-050). The

dust suppression system control is interlocked with the respective equipment and can also becontrolled by the operators in the CCCR. Dust suppression failure or shutdown will alarm in theCCCS and will trip equipment after a time delay.

L. A start command available from DCS will start the total equipment train from the dust collectorsto the apron feeders with a single command on a logical sequence. Likewise, the shut-downcommand can be initiated from DCS. Alternatively the operator can start and stop all equipmentseparately following the logical sequence. The CCCR operator selects which apron feeders hewants to operate.

M. The shut down sequence does not stop the dust collectors; they are operated continuously andare only shut down by the CCCR operator.

N. The following information will be available in the CCCR:

1. Status of ADS systems, dust collector fans, feeders, sump pump, conveyor and tripper

2. Surge bin levels

3. Coarse ore reclaim conveyor weigh scale readout

2.7 Secondary Crushing and Screening

A. The secondary crushing circuit consists of four lines each including a coarse ore surge bin (C-3220-BN-021/022/023/024), a belt feeder (C-3220-FE-3220-021/022/023/024), double deck


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screen (C-3220-SC-021/022/023/024) and a 750 kW cone crusher (C-3220-CR-041/042/043/044) operating in parallel. The screens separate the +50 mm material for crushing;

screen undersize is directed into a tertiary crushing circuit. Metal detectors are installed on thebelt feeders to prevent crusher liner damage. The feeder is stopped for the removal of the steeldetected.

B. The Feed into the crushers through screens is estimated by measuring the feeder speed(32SI_0407/0507/0607/0707) and the height of the ore on the feeder (32LI-0407/0507/0607/0707), which are used to control the variable speed feeders through the DCSsystem to provide steady feed to the crushers (32WIC-0407/0407/0607/0707). The secondarycrusher feed chute level is measured and controlled to ensure choke feed into the crusher(32LIC-0429/0429/0629/0729). The feed chute level controller provides the set point to the feedrate control.

C. The crusher power draw is measured and the feed rate into the crusher is reduced if the power

draw reaches a preset high limit (32J I-0416/0516/0616/0716). The high power draw controloverrides the feed chute level controls. The crusher setting is kept as fine as possible; avibration monitor is used to detect tramp metal relief system activation.

D. All four crusher products are discharged onto a common secondary crusher discharge conveyor(C-3220-CV-004). The discharge conveyor directs the product onto a secondary crusher producttransfer conveyor (C-3220-CV-005), which discharges onto the coarse ore tripper conveyor thusreturning the product back into the coarse ore surge bins.

E. The screen undersize is directed onto a coarse ore screen undersize conveyor (C-3200-CV-006), which discharges onto a coarse ore screen undersize transfer conveyor (C-3220-CV-007).

The screen undersize transfer conveyor feeds the HPGR surge bin feed conveyor (C-322-CV-008), which feeds the HPGR feed surge bins (C-3230-BN-031/032/033/034) through two HPGRshuttle conveyors (C-3220-CV-012/013). The shuttle conveyors are mounted on rails and moved

to feed the bin requesting the feed with four motorized wheels. A gate on a shuttle conveyorsplitter box (C-3220-ST-095) is used to direct the feed into one of the two shuttle conveyors.During normal operations only one of the shuttle conveyor needs to be operating.

F. The HPGR surge bin feed conveyor cannot be started before at least one of the shuttleconveyors is operating and the gate in the HPGR surge bin feed conveyor is in the right positionto feed the operating shuttle conveyor.

G. The shuttle conveyors are operated from the DCS to provide feed into the four HPGR surge binsdepending on the surge bin level. A gate in the HPGR surge bin feed conveyor head chute andthe shuttle conveyors are automatically operated to provide ore into the bin requesting feed. Thegate can be moved to provide feed into both shuttle conveyors simultaneously, if requested bythe operator.

H. Since the crushers are difficult start when they are loaded with ore, the crusher motors are onlystopped by internal drive system interlocks or on the following:

1. High-high vibration monitor reading (32VAHH-0436/0536/0636/0736) (NCT)

2. High-high discharge chute level (32LAHH-0418/0518/0618/0718) (NCT)


I. If any condition on the downstream equipment requires shutting down the crushing circuit, thefeeder only is shut down and the crusher and the screen are left running on stand by mode.


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PROCESS

J. The secondary crushing plant production is monitored by a coarse ore screen u/size belt scale(C-3220-SL-006) (32WI-1301) and the plant circulating load by the secondary crusher product

scale (C-3220-SL-004) (32WI-1201). The particle size distribution is monitored by a SPLITsystem camera (32AIT-1207).

K. All transfer chutes in the secondary crushing system are equipped with ADS dust control sprays,which are turned on and off automatically when the equipment are started or stopped. TheHPGR surge bins have dry dust collectors (C-3230-DC-071/072/073/074), which must berunning before the secondary crushing system can be started.

L. The equipment in the secondary crushing system will be started in the logical order starting fromthe shuttle conveyors on the screen underflow conveyor system and the secondary crusherproduct transfer conveyor on the crusher product conveyor system. Before the any of thecrushing lines can be started, the coarse ore reclaim conveyor and the dry dust collectors (C-3230-DC-071/072/073/074) need to be started. If a dust collector fan (C-3230-FA-

071/072/073/074) is tripped during operations an alarm is provided in the CCCR, but theconveyors are not automatically tripped (permissive controls).

M. The secondary crushing system can be started automatically with a start command from theDCS system. A permissive light will indicate when the system interlocks allow all the requiredequipment to start. A stop command will stop the line and empty all conveyors and chutesbefore stopping the equipment. The operator needs to select which crushers he would like tostart or stop before initiating the start up and shut down sequences. The operator can also startthe equipment in logical order manually from DCS.

N. A sump pump (C-3220-PP-021) in the secondary crushing area can be operated remotely fromthe CCCR or can be run automatically based on sump level.

O. In addition to electrical and drive system protective trips, the coarse ore screen feeders are

tripped for:1. Low-low coarse ore surge bin level (NCT)

2. Belt tear (32XA-0414/0514/0614/0714) (NCT)

3. High-high pulley bearing temperature (21TAHH-0432/0433 & 0532/0533 & 0632/0634 &0732/0733) (NCT)

4. Belt side travel (32ZA-0402/0409 & 0506/0509 & 0602/0609 & 0702/0709) (NCT)

5. Coarse ore screen stopped (C-3220-SC-021/022/023/024) (NCT)

6. High-high secondary crusher feed chute level (C-3220-ST-41/42/43/44) (NCT)

7. High-high screen undersize chute level (C-3220-ST-051) (NCT)

8. Coarse ore tripper conveyor (C-3210-CV-014) stopped (NCT)9. Coarse ore screen undersize conveyor stopped (C-3220-CV-006) (NCT)

10. Secondary crusher discharge conveyor stopped (C-3220-CV-004)

11. Pull cords (CST)

P. In addition to electrical and drive system protective trips, the coarse ore screens (C-3220-SC-021/022/023/024) are tripped on following:

1. Secondary crusher stopped (C-3220-CR-021/022/023/024) (NCT)


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3. Vibration monitor trip (32VAHH-0419/0519/0619/0719)NOTE!!!The coarse ore screen also trips the coarse ore feeders (C-3220-FE-

021/022/023/024)

Q. The secondary crusher discharge (C-3220-CV-004) conveyor trips on:

1. Electrical and drive system protective trips (CST)

2. High-high secondary crusher discharge conveyor head transfer chute level (C-322-ST-049) (NCT)

3. Secondary crusher product transfer conveyor trips (C-3220-CV-005) (NCT)


5. Pull cords (CST)


7. Belt side travel (32ZA-1206/1217) (NCT)

8. High-high pulley bearing temperatures (32TAHH-1203/1204) (NCT)

NOTE!!!The secondary crusher discharge conveyor also trips the coarse ore feeders (C-3220-FE-021/022/023/024)

R. The secondary crusher product transfer conveyor (C-3220-CV-005) trips on:


2. High-high secondary crusher product transfer conveyor head transfer chute level (C-322-ST-050) (NCT)

3. Coarse ore tripprer conveyor (C-3210-CV-014) stopped (NCT)



6. Pull cords (CST)


NOTE!!!The secondary crusher discharge conveyor also trips the coarse ore feeders (C-3220-FE-021/022/023/024) and the secondary crusher discharge conveyor (C-3220-CV-004)

S. The coarse ore screen undersize conveyor (C-3220-CV-006) trips on:


2. High-high coarse ore screen undersize conveyor head transfer chute level (C-322-ST-055)(NCT)

3. Coarse ore screen undersize transfer conveyor trips (C-3220-CV-007) (NCT)



6. Pull cords (CST)


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NOTE!!!

The coarse ore screen undersize conveyor also trips the coarse ore feeders (C-3220-FE-021/022/023/024)

T. The coarse ore screen undersize transfer conveyor (C-3220-CV-007) trips on:


2. High-high coarse ore screen undersize transfer conveyor head transfer chute level (C-322-ST-057) (NCT)

3. HPGR surge bin feed conveyor trips (C-3220-CV-008) (NCT)


5. Belt side travel (32-ZA-1351/1352)

6. Pull cords (CST)


NOTE!!!The coarse ore screen undersize transfer conveyor also trips the coarse orefeeders (C-3220-FE-021/022/023/024) and the coarse ore screen undersizeconveyor (C-3220-CV-006)

U. The coarse ore screen undersize conveyor is equipped with self cleaning belt magnet C-3220-MA-006), which needs to be running before the coarse ore screen undersize conveyor can bestarted. However, the belt magnet trip only provides an alarm on DCS, but does not trip thescreen undersize conveyor or related equipment during normal operations (permissive).

V. The HPGR surge bin feed conveyor (C-322-CV-008) trips on:


2. High-high HPGR surge bin feed conveyor head transfer chute level (32LAHH-1406) (C-322-ST-095) (NCT)

3. Both HPGR surge bin feed shuttle conveyors trip at the same time (C-3220-CV-012/013)(NCT)

4. Gate in HPGR surge bin feed conveyor head chute is jammed (32XA-1422) (NCT)

5. Belt tear (32XA-1421)


7. Pull cords (CST)


NOTE!!!HPGR surge bin feed conveyor (C-322-CV-008) also trips the coarse ore feeders(C-3220-FE-021/022/023/024), the coarse ore screen undersize conveyor (C-3220-CV-006), coarse ore screen undersize transfer conveyor (C-3220-CV-007),ball mill screen oversize conveyor (C-3310-CV-011) and ball mill screen feeders(C-3310-FE-101,102/201,202/301,302/401,402)

W. If both of the shuttle conveyors are operating and one of them is tripped, the gate directing feedinto the respective conveyor will be closed. If the gate does not close after a set time period, theHPGR surge bin feed conveyor will be tripped.


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X. The HPGR shuttle conveyor No. 1 (C-3220-CV-012) trips on the following:


2. High-high HPGR surge bin levels (C-3230-BN-031/032) (at the same time) (NCT)

3. Pulley bearing temperature (32TAHH-1501/1502) (NCT)



6. Pull cords (CST)

NOTE!!!The HPGR surge bin feed shuttle conveyor No. 1 (C-3220-CV-012) also tripsHPGR surge bin feed conveyor (C-322-CV-008) the coarse ore feeders (C-3220-

FE-021/022/023/024), the coarse ore screen undersize conveyor (C-3220-CV-006), coarse ore screen undersize transfer conveyor (C-3220-CV-007), ball millscreen oversize conveyor (C-3310-CV-011) and ball mill screen feeders (C-3310-FE-101,102/201,202/301,302/401,402) if the HPGR surge bin feed shuttleconveyor No. 2 (C-3220-CV-013) is not running

Y. The HPGR surge bin feed shuttle conveyor No. 2 (C-3220-CV-013) trips on the following:


2. High-high HPGR surge bin levels (C-3230-BN-033/034) (at the same time) (NCT)

3. Pulley bearing temperature (32TAHH-1503/1504) (NCT)



6. Pull cords (CST)

NOTE!!!The HPGR surge bin feed shuttle conveyor No. 2 (C-3220-CV-013) also tripsHPGR surge bin feed conveyor (C-322-CV-008) the coarse ore feeders (C-3220-FE-021/022/023/024), the coarse ore screen undersize conveyor (C-3220-CV-006), coarse ore screen undersize transfer conveyor (C-3220-CV-007), ball millscreen oversize conveyor (C-3310-CV-011) and ball mill screen feeders (C-3310-FE-101,102/201,202/301,302/401,402) if the HPGR surge bin feed shuttleconveyor No. 1 (C-3220-CV-012) is not running

Z. The following information will be available in the CCCR:

1. Status of ADS systems, dust collector fans, feeders, sump pump, conveyor and tripper

2. Surge bin levels

3. Coarse ore reclaim conveyor, secondary crusher product and screen undersize weighscale readout

4. Gate position

5. Tripper car position

2.8 Tertiary Crushing


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A. Four HPGR crushers (C-3230-CR-031/032/033/034), operating in parallel, are used in thetertiary crushing circuit. The crushers are fed with variable speed belt feeders (C-3230-FE-

031/032/033/034) from individual surge bins (C-3230-BN-031/032/033/034). The belt feedersare equipped with metal detectors (C-3230-MD-031/032/033/034). Gates in the feeder bypasschutes (C-3230-ST-076/077/078/079) are opened to direct the metal onto the HPGR dischargeconveyor (C-3230-CV-009) continuing onto the HPGR product conveyor (C-3230-CV-010) andthen into the ball mill feed surge bins (C-3310-BN-101/201/301/401).

B. As the HPGR crushers operate most efficiently with choke feed, level measurement and controlin the HPGR feed chute (31LIC-2121/2221/2321/2421) is used to maintain choke feed bycontrolling the feeder speed through a feed controller (32WIC-2107/2207/2307/2407) in DCSsystem. The tertiary crushing plant production is measured by a weight scale (C-323-SL-009) onthe HPGR discharge conveyor (C-3230-CV-009).

C. The HPGR crushers are equipped with variable speed drives (32SIC-2125/2210/2325/2420).

The speed is used to control the respective HPGR feed surge bin level (32LIC-2119/2203/2323/2423), the level controller provides the set point to the feeder speed. At high binlevels the speed is set at maximum, at low-low signal the feeder is stopped to prevent dumpingore onto an empty feeder. The CCCR operator provides the set point to the bin level. Ordinarilythe HPGR is not stopped automatically if the HPGR feed chute is empty, CCCR operator willdecide if the shutdown of the feed is long enough to justify shutting down the crusher. Normallythe crusher is shut down manually.

D. HPGR feed size is also monitored with cameras (32AI-2116/2227/2238/2436)

E. Each crushing line is equipped with an individual dust scrubber (C-3230-031/032/033/034). Acrushing line cannot be started before the respective scrubber is running. If the scrubber fan (C-3230-FA-031/032/033/034) will trip during operations, the feeder will trip and cannot be startedbefore the dust scrubber is operating. Effluent from the scrubbers is piped into scrubber effluent

sumps and pumped with scrubber effluent return pump (C-3230-PP-030) into primary cyclonefeed sumps. The operator can select remotely between two pump sumps in the grinding circuit(C-3310-BX-101 or 201) with remotely controlled valves (33XS-2111/2611/3111/3611) intowhich pump and sump and how much he selects to discharge the effluent. Pinch valves areused in control, the valve position determines the amount of effluent discharged into the pumpbox.

F. Water addition into scrubbers is remotely controlled with on-off knife gate valves. The effluentpump gland water is equipped with a local flow meter and low flow switch, which prevents thepump starting with low gland seal water flow. Low water flow during operations will alarm in theCCCR, but does not stop the pump.

G. The HPGR product conveyor discharges into the ball mill surge bins by a tripper car (C-3230-TR-010), which is automatically controlled by the DCS system to maintain proper bin levels. The

tripper car is equipped with proximity switches to provide the tripper car position and over travelswitch to shut down the tripper car if it goes over the end limit.

H. The HPGR plant production is monitored by a belt scale mounted on the HPGR dischargeconveyor (C-3230-SL-009) (32WI-3106). The HPGR product particle size distribution isestimated with a SPLIT camera system (32AI-3129)

I. Each ball mill surge bin is equipped with two dry dust collectors (C-3310-DC-101,102/201,202/301,302/401,402), which must be running before the HPGR product conveyorcan be started.


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J. The tertiary crushing system can be started automatically with a start command from the DCSsystem. A ready light will indicate when the system interlocks allow all the required equipment to

start. A stop command will stop the line and empty all conveyors and chutes before stoppingthe equipment. The operator needs to select which crushers he would like to start or stop beforeinitiating the start up and shut down sequences. The operator can also start the equipment inlogical order manually from DCS. Before using automatic start the operator needs to selectwhich crushers will be started.

K. A sump pump (C-3230-PP-031) in the HPGR area can be operated remotely from CCCR orautomatically on the sump level.

L. In addition to electrical and drive system protective trips, the HPGR feeders (C-3230-FE-031/032/033/034) are tripped for:

1. Low-low HPGR surge bin level (C-3230-BN-031/032/033/034) (NCT)

2. Metal bypass chute jammed (C-3230-ST-076/077/078/079) (NCT)3. HPGR stopped (C-3230-CR-031/032/033/034) (NCT)

4. High-high feeder discharge chute level (C-3230-ST-066/067/068/069) (NCT)

5. High-high bearing temperature (32TAHH-2131/2132 & 2231/2232 & 2331/2332 &2431/2432) (NCT)

6. Belt tear (32XA-2133/2236/2334/2433)

7. Belt side travel (32ZA-2137/2102 & 2211/2204 & 2309/2302 & 2409/2402)

8. HPGR discharge conveyor stopped (C-3230-CV-009) (NCT)

9. Pull cords (CST)

M. Since the crushers are difficult start if they are loaded with ore, the crusher motors are onlystopped by internal drive system interlocks or on the following:

1. High-high vibration monitor reading (NCT)

2. High-high discharge chute level (NCT)


N. The HPGR discharge conveyor (C-3230-CV-009) trips on:


2. High-high discharge conveyor (C-3230-CV-009) head transfer chute level (C-322-ST-086)(NCT)

3. HPGR product conveyor trips (C-3230-CV-010) (NCT)4. High-high pulley bearing temperatures (32TAHH-3101/3102) (NCT)

5. Belt tear (32ZA-3108) (NCT)


7. Pull cords (CST)

NOTE!!!HPGR discharge conveyor (C-3230-CV-009) also trips HPGR crusher feeders(C-3230-FE-031/032/033/034)


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O. The HPGR product conveyor (C-3230-CV-010) trips on:


2. High-high ball mill feed surge bin levels (C-3310-BN-101/201/301/401) (all at same time)(NCT)

3. High-high tripper car discharge chute level (C-3230-ST-087) (NCT)


5. Belt tear (32XA-3208)


7. Pull cords (CST)

NOTE!!!The HPGR product conveyor (C-3230-CV-010) also trips HPGR dischargeconveyor (C-3230-CV-009, and HPGR crusher feeders (C-3230-FE-031/032/033/034)

P. The following information will be available in the CCCR:

1. Status of ADS systems, dust collector fans, feeders, sump pump, conveyors and tripper

2. Surge bin levels

3. Weigh scale readout

4. Tripper car position

3. GRINDING


A. Four ball mills (C-3320-MI-101/201/301/401), operating in parallel mode are used to grind theHPGR product down to about 110 micron P80. Each ball mill receives feed from a surge bin withtwo parallel, variable speed belt feeders (C-3310-FE-101, 102/201, 202/301, 302/401, 402) eachfeeding a double-deck, vibrating screen. Feeders are equipped with feed rate controls (22WIC-1107, 1127/1207, 1227/1307, 1327/1407, 1427) and the set point for the throughput comes fromCCCR by the DCS system. Originally the throughput rate is set by the operator, later thethroughput will be controlled by an Expert System.

B. The feeders discharge into ball mill screen feed chutes, where water is added to dilute thescreen underflow density to about 36%. The slurried feed is directed onto double deck screens(C-3310-ST-105,106/205,206/305,306/405,406), where +6 mm material is transported back intothe tertiary crushing circuit and -6 mm material flows through the screen into a primary cyclonefeed sump. The +6 mm material is directed onto a ball mill screen oversize conveyor (C-3310-CV-011), which discharges onto the HPGR surge bin feed conveyor (C-3230-CV009).

C. The screens are mounted above the primary cyclone feed sumps (C-3310-BX-101/201/301/401), where the slurry from the screen underflow and ball mill discharge arecombined to produce the cyclone feed. The combined screen underflow and ball mill dischargeis pumped with primary cyclone feed pumps (C-3310-PP-101/201/301/401) into primary cycloneclusters (C-3330-CS-101/201/301/401). The primary cyclone underflow flows by gravity to the


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ball mills (C-3320-MI-101/201/301/401) via cyclone underflow launders (C-3230-LA-102/202/302/402). The discharge from the ball mill flows through a launder (C-3320-LA-

101/201/301/401) back into the primary cyclone feed sump.

D. The cyclone overflow is sampled with overflow samplers (C-3330-SA-101/201/301/401) andassayed with in stream analyzers (C-3330-SA-102/103). Only two analyzers are used as amultiplexer is used between two cyclone overflow samples. The samples are also analyzed forparticle size (C-3330-AZ-101/301). From the sampler the cyclone overflow is directed into theflotation circuit.

E. All equipment in the grinding circuit, except local manually controlled on-off valves, arecontrolled from CCCR.

3.2 Ball Mill Screen and Feeders

A. The mass flow onto the screens is estimated based on the feeder speed measurements (32SI-

1103/1123 & 1203/1223 & 1303/1323 & 1403/1423) and the ore bed height measurement. Themass flow set point is initially provided by the CCCR operators, later the mass flow will becontrolled by the expert system.

B. Ratio control (32FFIC-1101/1102 & 1201/1202 & 1301/1302 & 1401/1402) is provided betweenthe feeder tonnage and the water addition into the screen feed chutes (32FIC-1101/1102 &1201/1202 & 1301/1302 & 1401/1402) to maintain constant screen underflow density. Watersprays are also mounted on the top of the screen decks and the spray water addition ismonitored (32FIC-1130/1230/1330/1430). The quantity of spray water is controlled from DCS.

The spray water is automatically turned on when the screen is started and off when the screen isshut down. The ratio controller between the feed tonnage and screen feed chute water additionis automatically turned on to a predetermined set point and the water flow controller on remoteset point mode when the feeder is started

C. Water addition into the screen feed box is critical to prevent cyclone feed pump damage andplugging up the cyclone feed pipe. Therefore a deviation alarm between the screen feed waterflow set point and measurement will be programmed to warn the CCCR operator for possibledensity problems (32FAHL-1101/1102 & 1201/1202 & 1301/1302 & 1401/1402).

D. The screen feeder feed chute is equipped with a low chute level detector for feeder beltprotection (32LAL-1101/1121 & 1201/1221 & 1301/1321 & 1401/1421). To avoid disturbing thegrinding process the low level detector only provides an alarm for the CCCR operator, who hasto decide if an action is required or not.

E. The screen oversize conveyor is equipped with belt scales between every second screenoversize chute to allow estimating the actual feed into each ball mill by deducting the amount ofscreen oversize material from the screen feed 32WI-1536/1537/1538/1539).

3.3 Ball Mills and Cyclones

A. Cyclone feed density (33DI-2116/2616/3116/3616) and flow (33FI-2117/2617/3117/3617) ismeasured and the mass flow calculated (33FI-2118/2618/3118/3618). The cyclone feed densityis controlled with water addition into the ball mill discharge launder (33FIC-2204/2704/3204/3704) through the Expert System. Water is metered with magnetic flowmetersand controlled with pneumatically operated butterfly valves at every addition point in the circuit.

The pump box is equipped with local manual water addition point, which severs as a back upand commissioning water source.


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B. The primary cyclone feed sump level is measured and controlled with the primary cyclone feedpump (C-3310-PP-101/201/301/401) speed. The pump intake is equipped with automatic water

flush and isolation valve. Both the pump sump and the pump intake pipe have automatic drainvalves. When the cyclone feed pump is tripped, the isolation valve closes and the sump andpump drain valves open automatically to drain the cyclone feed pipe and sump.

C. Before the cyclone feed pump can be started, the pump sump drain valve, the pump inlet drainvalve and the pump flush water valve need to be closed and the isolation valve opened.

D. The valves are detailed in the table as follows:

Pump PumpboxDrain Valve

Pump DrainValve

Pump InletValve

Flush WaterValve

C-3310-PP-101 33XS-2101 33XS-2102 33XS-2104 33XS-2103C-3310-PP-102 33XS-2601 33XS-2602 33XS-2604 33XS-2603

C-3310-PP-103 33XS-3101 33XS-3102 33XS-3104 33XS-3103C-3310-PP-104 33XS-3601 33XS-3602 33XS-3604 33XS-3603

E. Gland seal water to the primary cyclone feed pump is measured with a local flow meterequipped with a low flow switch. The gland seal water line has a manual shut off valve. Interlockin DCS prevents starting up the pump with low gland seal water flow and provides an alarm, butdoes not trip the pump, during normal operations. The gland water system is also equipped withlow gland water pressure alarm

F. The cyclone cluster consists of 14 660 mm cyclones with automatic shut off valves. The cyclonefeed pressure (33PIC-2222/2722/3222/3722) is measured and controlled by automaticallyopening and closing cyclones. Water is added into cyclone overflow (33FIC-2202/2702/3202/3702) and underflow (33FIC-2203/2703/3203/3703) launders through magneticflow meters and control valves. A density measurement on the cyclone overflow line is used to

control the feed density into the flotation circuit, a density controller in DCS automatically adjuststhe water addition into the cyclone overflow launder.

G. A sump pump (C-3310-PP-103/203/303/403) in the ball mill area can be operated remotely fromthe CCCR or automatically based on the sump level.

H. For a normal shut down for maintenance purposes the following sequence is to be used:

1. Shut down belt feeders

2. After the screens have run empty, shut down screens and close screen water valves

3. Turn the ball mill discharge launder water controller on manual mode

4. In the CCCR, place pump flow controller in automatic and ramp down flow set point afterone minute to a minimum recommended flow set point

5. Leave pump running and monitor cyclone feed density until density is below 1.1 t/m3

6. Stop pump

7. Close ball mill discharge launder water valve and open suction and side drain valve

I. In order to restart the system after a shut down the following procedure is to be used:

1. Close suction side drain valve.


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2. Open ball mill discharge launder water valve

3. Start pump on water in manual at low speed4. Start double deck screens, turn spray water on

5. Turn screen feed box water addition controller on automatic mode

6. Start ball mill screen feeders

J. The drive unit for the cyclone feed pumps will be equipped with a forced oil gearbox lubricationunit.

K. Each ball mill has a wrap around variable speed motor and caliper brake. The caliper brake isdesigned to be fail closed, that is, it uses hydraulic fluid to open and a spring to close. Normalstarting operation of the mill will release the caliper brake and starts ramping the ball mill speedup to the operating speed. Normal stopping operation will ramp the speed of the mill to zero and

then apply the caliper brakes. A ball mill fault condition (e.g., lubrication system failure, motorfailure, loss of power) will cause the motor to stop and the caliper brakes to instantly close. Referto the ball mill operation manual for a complete description of mill operation.

L. The vendor-supplied control system for the ball mill and wrap around motor will provide allelectrical system, lubrication system and other required protective trips for the mill and millmotor. Ball mill and motor alarm and trip monitoring will be performed from the CCCR with adiagnostic display also available in the ball mill motor cycloconverter drive electrical room. Inaddition to electrical, drive system and mill/motor lubrication system protective trips, the ball millis provided with the following personnel and protective trips:

1. Emergency stop local push buttons (CST)

2. Feed chute attached to trunnion liner (kirk key interlock)

M. The ball mill and wrap around, variable speed drive motor will be controlled by a vendor suppliedcontrol system (PLC) which interfaces with the plant control system (DCS). The speed of the ballmill will be controlled by an operator-specified set point. The ball mill will normally be operatedfrom the Concentrator central control room (CCCR). A local motor control panel will be providedon the mill operation platform adjacent to the ball mill. Ball mill inching operations will beperformed from this local panel only.

N. Primary collector, secondary collector (if required), moly collector and milk of lime are alsoadded to the ball mill at the cyclone underflow launder. The collector addition rates will becontrolled by operator specified set points or by ratio control cascaded from the ball mill feedweight controller. (Collectors are added proportionally to new feed weight, with adjustments tothe rate for variations in feed grade). Lime addition is controlled to an operator specified pH setpoint, with pH measurement downstream in the cyclone overflow (33AIC-2401/2402/3401/3402).

3.4 System Interlocks

A. In addition to electrical and drive system protective trips, the ball mill screen feeders (C-3310-FE-101,102/201,202/301,302/401,402) are tripped for the following:

1. Ball mill tripped (C-3320-MI-101/201/301/401) (NCT)

2. Cyclone feed pump tripped (C-3310-PP-101/201/301/401) (NCT)

3. High-high feeder discharge chute level (C-3310-ST-103,104/203,204/303,304/403,404)(NCT)


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4. High-high screen oversize chute level (C-3230-ST-105,106/205,206/305,306/405/406)(NCT)

5. High-high screen undersize chute level (C-3310-ST-107,108/207,208/307,308/407,408)(NCT)

6. Screen oversize conveyor tripped (C-3310-CV-011) (NCT)

7. Ball mill feed screen tripped (C-3310-ST-105,106/205,206/305,306/405,406) (NCT)

8. HPGR surge bin feed conveyor tripped (C-3220-CV-008) (NCT)

9. Both HPGR shuttle conveyors tripped (C-3229-CV012/013) (NCT)

10. High-high pulley bearing temperatures (33TAHH-1116/1117 & 1125/1126, 1216/1217 &1225/1226, 1316/1317 & 1325/1326, 1416/1417 & 1425/1426) (NCT)

11. Belt tear (33XA-1108/1128 & 1208/1228 & 1308/1328 & 1408/1428) (NCT)

12. Belt side travel (33ZA-1102/1109 & 1122/1129, 1202/1209 & 1222/1229, 1302/1309 &1322/1329, 1402/1409 & 1422/1429)

13. Pull cords (CST)

B. The screen oversize conveyor (C-3310-CV-01) trips on:


2. High-high head chute level (C-3310-ST-091) (NCT)

3. HPGR surge bin feed conveyor trip (C-3220-CV-008)

4. Both HPGR shuttle conveyors tripped (C-3229-CV012/013)




8. Pull cords (CST)

NOTE!!!Screen oversize conveyor (C-3310-CV-01) trips the ball mill screen feeders (C-3310-FE-101,102/201,202/301,302/401,402)

3.5 Ball Mill Grinding Ball Addition

A. Ball mill grinding balls are stored in a ball storage bin (C-3320-BN-051) located on the north westcorner of the grinding building. The ball mill ball storage bin (C-3320-BN-051) is located below adump pocket and is fed directly by ball transport trucks. Balls are discharged from the ballstorage bin onto a high lift conveyor (C-3320-CV-021) by means of a fixed speed rotary drumfeeder (C-3320-ZM-040) and discharge chute (C-3320-ST-114). The ball charge rotary drumfeeder is interlocked with the high lift conveyor (C-3320-CV-021). The ball feed rate is measuredby means of a belt scale (C-3320-SL-022) on the ball mill ball transfer conveyor (C-3320-CV-022). The belt scale reading and the diverter gate positions are used to summarize the balladdition to individual mills (33WIQ-4126/4121/4122/4123).

B. In addition to electrical protective trips, the ball charge high lift conveyor (C-3320-CV-021) isprovided with the following protective trips:

1. Plugged discharge chute (C-3320-ST-115) (33LAHH-4101) (NCT)


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2. Ball mill ball transfer conveyor (C-3320-CV-022) stopped (NCT)

C. Balls are transferred from the high lift conveyor (C-3320-CV-021) to the ball mill ball transferconveyor (C-3320-CV-022) via transfer chute (C-3320-ST-115). Automatic diverter gates (C-3320-ZM-101/201/301/401) located on the ball mill transfer conveyor (C-3320-CV-022) will beused to direct balls to each individual mill. The diverter gates will be used to direct the balls tothe desired mill as and when required. The balls will fall via gravity to each mill circuit via a feedchute (C-3320-ST-113/213/313/413) and the individual ball mill cyclone underflow chute. Excessballs on the conveying system not diverted to any mill will be conveyed to the Ball Mill BallOverflow Bin (C-3320-BN-052) via the ball mill ball overflow chute (C-3320-ST-116).

D. In addition to electrical protective trips, the ball transfer conveyor (C-3320-CV-022) is providedwith the following protective trips:

1. All diverter gates are open (C-3320-ZM-101/201/301/401) (NCT)

2. More than one diverter gate is open (C-3320-ZM-101/201/301/401)\3. Belt tear (33XA-4118) (NCT)


E. Grinding balls can be added using a ball bucket and an overhead crane if the automatic systemis down. A hook mounted scale (C-3320-SL-020) can then be used to estimate the ball additionto mills.

4. FLOTATION


A. The rougher-scavenger flotation circuit is set up as four (4) rows of ten (10) flotation cells. Each

flotation cell is 160 m3 and the ten cells in each row of cells are set up in pairs of two cells eachwith level control between each pair of cells. The first two cells in each row of cells haveindividual level controls. Each row of rougher-scavenger cells is gravity fed by the overflow fromeach of the four primary grinding cyclones.

B. The first cell in each row of cells is used as a rougher flotation cell. Concentrate from each ofthese cells is collected via gravity and sent to the polishing mill circuit. The second cell in eachrow of cells will normally be used as a scavenger cell but can also be used as a rougher cell, asrequired. The remaining eight (8) cells per row are to be used exclusively as scavenger flotationcells. Cells are numbered as follows:

Row one Rougher cells 3410-CF-101/102Scavenger cells 3410-CF-103 to -110

Row two Rougher cells 3410-CF-201/202Scavenger cells 3410-CF-203 to -210

Row three Rougher cells 3410-CF-301/302Scavenger cells 3410-CF-303 to -310

Row four Rougher cells 3410-CF-401/402Scavenger cells 3410-CF-403 to -410

C. Frother is added to the first, third, fifth, and seventh rougher flotation cell (4 in total). Primarycollector, secondary collector and molybdenum collector are added to the third, fifth and seventhscavenger flotation cells. Refer to section 5.0 Reagents for more detail.


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D. Rougher concentrate from each row of cells flows via gravity to the rougher concentratesamplers (3410-SA-103/104 & 3410-SA-303/304) for on stream analysis (3410-AZ-103/104 &

3410-AZ-303/304) and collection of shift samples. All of the four rougher concentrate streamsare collected in one launder (3410-LA-105) after analysis and fed via gravity to the polishing millfeed pumpbox (3420-BX-501) from where it is pumped via one of two transfer pumps (3420-PP-501/502) to the polishing mill feed distributor (3420-DI-502) and fed by gravity to the rougherconcentrate polishing mills (3420-ML-501/502). The rougher concentrate is milled to a targetvalue of 80% passing 50 microns in the polishing mills (3420-ML-501/502). The discharge fromthe rougher concentrate polishing mills flows by gravity to a sampler (3420-SA-501) for onstream analysis (3420-AZ-501) and particle size analysis (3420-AZ-502). The main processstream from the sampling system falls via gravity into the column cell feed pumpbox (3420-BX-502) from where it is pumped via one of two column cell feed pumps (3420-PP-503/504) to thecolumn cell feed distributor (3430-DI-501).

E. Scavenger concentrate, from each row of cells flows via gravity to the scavenger concentrate

samplers (3410-SA-203/204 & 3410-SA-403/404) for on stream analysis (3410-AZ-203/204 &3410-AZ-403/404) and collection of shift samples. All of the scavenger concentrate streams arecollected in one launder (3410-LA-106) after analysis and fed via gravity to the scavengerconcentrate collection pumpbox (3420-BX-503). This pumpbox is sized at fifty (50) m3 toaccommodate reasonable fluctuations in concentrate production rates and minimize surge indownstream processes.

F. Scavenger flotation tailing from each row of cells pass through individual sample stations (3410-SA-102/202/302/402) where on stream analysis (3410-AZ-103/203/303/403) is carried out andshift samples collected. The tailing stream from each tailing sampler falls into a tailing collectionlaunder (3710-LA-001) and are transported via gravity to a bulk plant tailing sampler (3710-SA-001) and analyzer (3710-AZ-001) before being split into two streams and fed to the tailingthickeners.

G. Recycle streams from the regrind mills (3420-ML-503/504/505) and the cleaner scavengerconcentrate stream are combined in the scavenger concentrate pumpbox (3420-BX-503). Theregrind cyclone feed pumps (3420-PP-505/506) are used to feed the combined concentratesfrom the scavenger concentrate pumpbox to the regrind cyclone cluster (3420-CS-501). Dilutionwater is added to the scavenger concentrate pump box to allow for cyclone feed density control.

The cyclone underflow passes through the cyclone underflow launder (3420-LA-501) to theregrind mill feed pumpbox (3420-BX-504), in which the slurry density is controlled throughaddition of process water and the flow is split to feed each regrind mill (3420-ML-503/504/505).

The underflow from the cyclone underflow launder flows via gravity to the regrind mill feedpumpbox (3420-BX-504) and feed pumps (3420-PP-507/508/509). The regrind mill feed streamis fed into the bottom of the regrind mills and flows up through the mills and via gravity from themill discharge to the scavenger concentrate collection sump (3420-BX-503).

H. The regrind cyclone overflow stream is split and one stream is fed through a gravity sampler(3420-SA-504) for particle size analysis (3420-AZ-502), and then flows via gravity to thescavenger concentrate collection pumpbox (3420-BX-503). The second stream split from theregrind cyclone overflow flows via gravity to the feedbox of the first cleaner flotation cells (3430-BX-505). The first cleaner and cleaner scavenger cells are one row of ten (10) one hundred andsixty cubic meter cells (160m3). The first six cells are the first cleaner cells and the last four cellsthe cleaner scavenger cells. Concentrate from the first cleaner cells (3440-CF-501 to -506) flowsvia gravity to the column cell feed sampler (3420-SA-502) and analyzer (3420-AZ-501) beforefalling via gravity into the column cell feed pumpbox (3420-BX-502). Concentrate from thecleaner scavenger cells (3440-CF-507 to -510) flows via gravity to the column cell feed sampler


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(3420-SA-503) and analyzer (3420-AZ-501). This concentrate material then flows to the regrindcircuit via the scavenger concentrate pumpbox (3420-BX-503).

I. The tailing stream from the cleaner scavenger cells flow via gravity through a tailing sampler(3440-SA-513) and analyzer (3440-AZ-505) before flowing via gravity into the combinedscavenger tailing collection launder (3710-LA-001).

J. Concentrate from the column cell feed pump box (3420-BX-502) is fed via the column cell feedpumps (3420-PP-503/504) to the column cell feed distributor (3430-DI-501). The distributorsplits the stream into four (4) streams, which are then fed into the four column cells (3430-CM-501/502/503/504). The column cells are each 5.0 m diameter and 12.0 m high.

K. Tailing material from each column flows via gravity through a column tailing sampler (3430-SA-509 to -512) and a shared analyzer (3420-AZ-504) before falling via gravity into the column celltailing pump box (3430-BX-505). The tailing is then pumped via the column tailing transferpumps (3430-PP-512/513) to the first cleaner cells.

L. Concentrate from each column flows via gravity through a column concentrate sampler (3430-SA-505 to -508) and a shared analyzer (3420-AZ-503) before falling via gravity into the columnconcentrate pump box (3430-BX-506). The concentrate is then pumped via the columnconcentrate transfer pumps (3430-PP-504/515) to the bulk concentrate thickener feed box(3510-BX-003).

M. Each cell or pair of cells is equipped with froth vision cameras for future froth rate controls.

N. All equipment in the flotation and regrind areas will be controlled from the concentrator centralcontrol room (CCCR). Ability to control locally from the field will also be provided.

O. Floor sump pumps in the cleaner flotation and regrind areas can be started and stoppedremotely from CCCR or operated automatically based on sump level. The status of the pump

and the sump level are displayed in the CCCR.

P. In general, launder spray water addition is performed manually. Process water will be piped toprocess sumps for commissioning, startup and spray water requirements. Process water isadded to the combined scavenger concentrate collection pumpbox (3430-BX-506) and regrindmill feed pumpbox (3420-BX-504) and is measured and controlled to achieve the desired pulpdensities in the flows to the first cleaner cells and the regrind mills.

4.2 System Interlocks.

In general, there are no flotation system interlocks between pieces of equipment, with the exceptionof the regrind feed pumps which cannot be started unless the respective vertimill is running. Moredetailed trip information is provided in the individual section descriptions.

4.3 Rougher and Scavenger Flotation

A. Cyclone overflow from the grinding circuit flows by gravity to the rougher flotation feed distributor(3310-DI-003) and then to each row of flotation cells.

B. A total of forty (40) rougher and scavenger flotation cells are provided in four (4) rows of ten (10)cells each. The first cell in each row of cells is to be used as a rougher flotation cell, the secondcell in each row as either a rougher or scavenger cell and the remaining eight (8) cells in eachrow as scavenger cells. The cells except the first two on each row are all installed as pairs ofcells, with five (5) pairs of cells per row. The first cell has a feedbox and separate level controls.


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Frother is added to the first, third, fifth, and seventh flotation cells in each row. Primary collector,secondary collector and moly collector are

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c Ot 25 001_rev B_process Description Control Philosophy

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