Process Control Philosophy

BENDIGO MINING LIMITED

BENDIGO GOLD PROJECT

PROCESS CONTROL PHILOSOPHY

Client Approval:

Date:

Document No. Rev.

1475-CP-001-E E

REV. DATE DESCRIPTION AUTHOR APPROVED

A 25-01-05 DRAFT FOR REVIEW THB 28-04-05 GENERAL UPDATE TH

C 31-08-05 POST HAZOP UPDATE TH

D 05-12-05 GENERAL UPDATE TH MD

E 10-02-06 GENERAL UPDATE TH IJM

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BENDIGO MINING LIMITED PROCESS CONTROL PHILOSOPHYBENDIGO GOLD PROJECT

TABLE OF CONTENTS

1 INTRODUCTION 1

2 PROCESS DESCRIPTION 1

3 GENERAL 2

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3.1 Control System 23.2 Drives 43.3 Alarms 63.4 Common Functions 7

4 PROCESS PLANT CONTROL PHILOSOPHY 10

4.1 Crushing 104.2 Fine Ore Bin, HPGR, Grinding and Gravity 11



4.3 Flotation 144.4 Reagents and Consumables 174.5 Services 224.6 Gravity Concentrate Leaching 244.7 Flotation Concentrate Leaching 254.8 Carbon Stripping 264.9 Electrowinning 284.10 Cyanide Detoxification 29



5 PERMISSIVES AND INTERLOCKS 30

5.1 General 305.2 Crushing 315.3 Fine Ore Bin, HPGR, Grinding and Gravity 325.4 Flotation 335.5 Reagents and Consumables 345.6 Gravity and Flotation Concentrate Leaching 355.7 Carbon Stripping 35



5.8 Electrowinning 355.9 Cyanide Detoxification 36

6 PROCESS CONTROL LOOPS 37

6.1 Crushing 376.2 Fine Ore Bin, HPGR, Grinding and Gravity 386.3 Flotation 436.4 Reagents and Consumables 48



6.5 Gravity and Flotation Concentrate Leaching 546.6 Carbon Stripping 556.7 Electrowinning 556.8 Cyanide Detoxification 56

7 SEQUENCES AND PROCEDURES 57

7.1 Crushing 577.2 Grinding and Gravity 59



7.3 Flotation 637.4 CIL and Detox 657.5 Acid Wash Procedures 677.6 Elution Procedures 69

APPENDIX 1 SCHEDULE OF ALARMS 72

Appendix 2 PIPING & INSTRUMENTATION DIAGRAMs 79




1 INTRODUCTIONThe Bendigo Gold Project is located at Bendigo in central Victoria, Australia. Ore is sourced from extensions and developments to underground workings. The plant is designed to process 600,000 tonnes per year of ROM ore. The plant recovers gold from the ore by a combination of gravity concentration, flotation and intensive cyanidation of concentrates.

This document describes the process plant and the control philosophy.

2 PROCESS DESCRIPTIONProcessing of gold bearing ore includes the following activities:

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Crushing

Grinding and gravity concentration

Flotation

Cyanidation of gravity and flotation concentrates

Acid washing and elution of loaded carbon

Regeneration of eluted carbon

Detoxification of cyanidation tailings slurry

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Electrowinning and smelting of doré bullion

Reagent mixing, storage and distribution

The plant design relies on the recovery of gold using gravity recovery methods (gold trap, jigs, and centrifugal concentrators). It is expected that up to 70 % of the gold in the ore is recovered this way and the recoverable remainder collected by froth flotation. Gravity recovery and froth flotation techniques produce concentrates. Gravity concentrates are upgraded using a jig and shaking tables. Shaking table tails are intensively leached using cyanidation and gold electrowon from the leach solution. Flotation concentrates are treated using the CIL process. Gold is eluted from loaded carbon and electrowon from the eluate solution.

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Ore is delivered by truck from the underground mining operation to a run of mine (ROM) storage pad. A front-end loader transfers ore from the ROM pad stockpile to the two stage crushing plant. A conveyor delivers crushed ore to the fine ore bin. Crushed ore reclaimed from the fine ore bin is fed to the high pressure grinding rolls crusher (HPGR) operating in closed circuit with the ball mill screen. Coarse gravity gold is recovered in the ball mill screen gold trap in the screen feed box. The screen undersize is pumped to the primary jigs. Jig tails gravitate to the centrifugal concentrator. Spinners upgrade jig concentrates.

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Tails from the centrifugal concentrator are pumped to the mill cyclone cluster. The cyclone underflow gravitates to the ball mill feed chute. Ground ore slurry discharging from the ball mill combines with mill screen undersize in the mill pump hopper. The slurry is pumped back to the gravity gold recovery circuit. The cyclone overflow slurry gravitates to the float feed thickener to remove excess water. Thickener underflow is pumped to the conditioning tank where dilution water, activator, collector and frother are added.

Gold concentrate from the gold trap discharges into a kibble in the goldroom. Spinner and centrifugal concentrator concentrates are periodically flushed to the gravity concentrate surge tank and pumped to the gravity concentrate tank in the goldroom.

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Coarse concentrates from the gold trap are sorted to recover coarse gold nuggets. After sorting, coarse concentrates are crushed using the concentrate roll crusher and fed to the goldroom gravity spinner. Goldroom gravity spinner tails, with accumulated spinner and centrifugal concentrator concentrates, are fed to the goldroom fine screen. Oversize concentrates are re-crushed and fed to the Concentrate Roll Crusher and fed back to the goldroom gravity spinner. Fine concentrates are fed to the concentrate jig. Jig concentrates are upgraded using two shaking tables and the concentrate calcined for direct smelting. Jig and table tails (middlings) are leached in a proprietary system (Intensive Leach Reactor or ILR) where gold dissolves under aggressive reaction conditions in an enclosed rotating drum. Cyanide and sodium hydroxide solutions are added to the ILR. Solution containing solubilised gold (electrolyte) is circulated through an electrowinning cell and recycled to the ILR.

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The overflow of the conditioning tank feeds the flotation cells. Flotation concentrate slurry is pumped to the concentrate thickener. Tails slurry is pumped to the sand cyclone. Fines are removed in the cyclone overflow. The cyclone underflow (sands) slurry is diluted and pumped to a section of the tailings storage facility. The cyclone overflow slurry gravitates to the flotation tail thickener to remove excess water. Thickener underflow is pumped to the flotation tailings storage facility. Supernatant water is decanted from settled solids and pumped back to the process water tank.

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The flotation concentrate slurry is thickened to remove excess water and combined with tails slurry from the ILR. The combined slurry, screened to remove trash, is mixed with lime slurry and pumped to the CIL circuit. Sodium cyanide is added to the slurry before is enters the agitated CIL tanks. Dissolved gold is adsorbed onto activated carbon granules. After acid treatment of the loaded carbon, gold is stripped (eluted) from the activated carbon into a gold bearing solution (eluate). The eluate is circulated through a separate dedicated electrowinning cell. Barren activated carbon is processed through a kiln to restore the gold adsorption capacity and added back to the agitated leach tanks.

The leached slurry discharged from the agitated CIL tanks is treated in a cyanide detoxification system to reduce the cyanide concentration to below permitted limits and pumped to a separate tailings storage facility.

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Goldroom activities include upgrading of the gravity concentrates and monitoring of electrowinning from the electrolytes from the ILR and elution systems. Gold in the electrolytes plated onto cathodes is periodically removed by washing cathodes with a high-pressure water spray. Washings are filtered and dried in an oven with the shaking table concentrates and smelted with fluxes into doré bullion.

The reagent area includes facilities for the offloading, mixing, storage and distribution of flotation collector, activator, frother, flocculant, hydrated lime, sodium hydroxide, sodium cyanide, sodium metabisulphite and hydrochloric acid. The actual reagents used will vary from time to time depending on cost, performance and availability.

3 GENERAL

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3.1 Control SystemThe control philosophy implemented for the Bendigo Gold Project is a typical system employed in Australian mineral processing operations. Field instrumentation provides a number of inputs to a set of programmable logic controllers (PLCs). The PLCs also collect status information on all process drives and process states as well as providing drive control and process interlocking.

Standard personal computers (PC) are located in the Main Control Room (MCR) and the Crusher Control Room (CCR), and networked to the PLCs. The computers operate a Supervisory Control and Data Acquisition (SCADA) program for control and monitoring of the relevant sections of the plant. The SCADA is configured to provide outputs to alarms, control the function of selected process equipment, and provide logging and trending facilities to assist in analysis of the operating plant.

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The CCR and MCR are purpose built structures, located in the crushing and mill buildings respectively. The CCR houses one control room operator station and the MCR houses one control room operator station, one engineering station and a printer. The control room operator station provides the following functions:

Graphic (mimic) displays of all plant areas, showing equipment status (ready, not-ready or running) and analogue values for critical process variables

Alarm display and logs, showing the alarm tag number, title, date and time

Trend displays with flexible time and process variable axes for any analogue process variable


Loop displays showing controller settings and trending of process variable, set-point and output

The control room operator stations are supplied from an uninterruptible power supply (UPS) unit with twenty minutes standby capability.

Drives that form part of a vendor package shall be controlled from the vendor’s control panel. As a minimum, ‘Run’ and ‘Fault’ signals from each vendor control panel are made available to the SCADA system via the PLC.

The PLCs perform the control of the plant with the SCADA system providing an interface to the PLCs which:

collect status information of drives, process instrumentation and packaged equipment;


provide drive control and process interlocking; and

perform PID control for process control loops.

Access to various controls and set-points within the SCADA system are protected by a password system. All users have “view” level access to all areas. The following user accounts are used, with the corresponding access level:


USER ACCESS LEVELOperator Plant area controls and alarms, control loop set-points, trends

Supervisor As per Operator, plus alarm set-points, reset of totalisers bypass interlocks

Engineer As per Supervisor, plus PID control loop tuning parameters and hardware settings

The SCADA system contains several graphics replicating the process flow sheets. The screens have dynamic displays of drive status, process status and indication for process quantities.

All drives are shown in graphical format. The colour of the symbol represents the state of the drive as follows:


COLOUR DENOTATION

YELLOW Drive Fault , Drive Isolated - LOS, Lanyard or De-contactor operated

ORANGE Drive ready, but with unhealthy process interlocks

RED Drive and interlocks ready - stopped able to be started

GREEN Running


All controlled valves are shown in graphical format. The colour of the symbol represents the state of the valve as follows:

COLOUR DENOTATION

RED Valve closed

GREEN Valve open

YELLOW Fault

BLUE Valve travelling


The control loops described can be found on the Piping and Instrumentation Diagrams (P&IDs) attached in Appendix 1.

3.2 Drives

Certain equipment is started by PLC controlled group sequences wherever possible, e.g. the crushing section. Using the sequences allows the control room operator to start or shut down sections of the plant faster, without risk associated with distractions.

Equipment drives have three modes of operation: namely “AUTO”, “MANUAL” and “MAINTENANCE”.


3.2.1 Auto Mode

In “AUTO” mode, the drive is automatically started and stopped by the PLC program for drives that belong to a particular group sequence control. A group sequence cannot be initiated if any equipment in that sequence is not in “Auto” mode. The group sequences include an “ALL TO AUTO” pushbutton, which sets all drives related to that sequence into AUTO mode.

Certain drives that are not necessarily associated to a group sequence may need to be set to “AUTO” mode such as sump pumps, so that they will automatically start and stop based on the activation of a level switch or other such field device.


Drives that do not require “AUTO” mode will have the AUTO mode selection disabled in the PLC code. These drives will not have the AUTO mode pushbutton shown on the Citect SCADA motor faceplate.

AUTO mode cannot be selected on the drive faceplate when the drive is faulted.

In AUTO mode, all process interlocks must be satisfied for the drive to run.

In AUTO mode, the operator may initiate a start and stop the drive from the Citect SCADA system. The drive will run, provided that the process interlocks are satisfied. The drive will be switched from AUTO to MANUAL mode if the Citect stop pushbutton is initiated, as well as stopping the drive.


In AUTO mode, the operator may also start and stop the drive from the Local Control Station (LCS). The drive will run provided that the process interlocks are satisfied.

Switching of the drive mode from AUTO to MANUAL will keep the drive at its current state (i.e. drive will stay running).

Switching of the drive mode from AUTO to MAINTENANCE will stop the drive.

3.2.2 Manual Mode


In “MANUAL” mode, the individual drive is requested to start and stop from the Citect SCADA system and the drive is under the control of the PLC program. In Manual mode, all process interlocks must be satisfied for the drive to run.

In MANUAL mode, the operator may also start and stop the drive from the Local Control Station (LCS). The drive will run provided that the process interlocks are satisfied.

Switching of the drive mode from MANUAL to AUTO will keep the drive at its current state (i.e. drive will stay running).

Switching of the drive mode from MANUAL to MAINTENANCE will stop the drive.


3.2.3 Maintenance Mode

In “MAINTENANCE” mode, the operator only starts and stops the drive from a field stop/start station located adjacent to the drive.

In this mode, all process interlocks are bypassed and not effective. It is assumed that in MAINTENANCE mode the field operator will be in full control and supervising the drive.

When switching a drive into MAINTENANCE mode the drive will be stopped.

Switching of the drive mode from MAINTENANCE to MANUAL mode or MAINTENANCE to AUTO mode will keep the drive at its current state.


In MAINTENANCE mode a “spanner” symbol appears adjacent to the drive shown on the mimic display.

3.2.4 General Features

Modes are displayed on the Citect mimic pages by the colour of the equipment tag name box. The equipment tag name box identifies the equipment name using a black text on a coloured or clear background box. The background box colours are:

Maintenance Mode = turquoise.

Manual = pale blue.


Auto = clear (no colour)

The selection of either mode is made via three separate push buttons on the equipment motor control faceplates. A coloured border appears around the selected mode push button to denote that it is selected.

The drives depicted on the mimic pages change colour to denote:

Drive Stopped and Ready for Start = Red

Drive Running = Green

Drive Faulted = Yellow


Drive Interlock is present = Orange.

The Local Control Station stop button is always functional regardless of mode selected.

Safety interlocks such as conveyor pull wires, which must remain operational at all times, are hardwired. All other interlocks are implemented in the PLC.

3.2.5 Bypass Interlocks in auto or manual mode


The motor drive faceplates include a tick box for interlocks. Ticking this box displays all of the interlocks programmed for the drive within the PLC. SCADA users with Supervisor or Engineer level access only may bypass interlocks on any item via a right click on the interlocks display then selecting bypass on the equipment motor control faceplate if required. SCADA users with Operator level access will find the check box on the equipment motor control faceplate disabled.

3.2.6 Symbols

Symbols appear adjacent to the drives as well as other control equipment to denote an abnormal control condition.

These symbols are shown and described on the SYMBOLS LEGEND page.


3.3 AlarmsAlarms are categorised according to relative importance as follows:

1. CRITICAL = RED TEXT

These are those alarms that may cause harm to personnel or equipment damage if condition remains unattended.

2. PROCESS = YELLOW


These are process type alarm conditions, such as equipment stopping, levels, or other field devices that stop or have certain effect on the process plant areas and require operator intervention.

3. EVENT= GREEN


These are warning and notification type alarms. The alarm advises the operator that certain conditions have changed on his plant and may require action or intervention. In some instances an EVENT type alarms could lead to a PROCESS alarm if the alarm remains unattended.

A schedule of alarms and their category is presented in Appendix 1.

3.4 Common FunctionsA number of common control functions are provided throughout the plant. These are listed here to avoid repetition throughout detailed descriptions.

3.4.1 Conveyors


Conveyors are fitted with speed sensors to detect low speed or belt slip, limit switches to detect belt drift, pull-wire switches to stop the conveyor in an emergency and start-up sirens and flashing light beacons to advise of an imminent start.

3.4.2 ChutesWhere applicable, chutes are fitted with a laser (or suitable alternative) level switch or transmitter to alarm on blockage at high level and stop equipment feeding the chute.

3.4.3 Pump Hopper Levels


A number of the pump hoppers are fitted with level control. This generally includes an ultrasonic level probe mounted over the hopper providing input to a level control loop. The level set-point that is entered by the operator is maintained by the loop output adjusting the speed of the associated pump. Level monitoring includes various alarms including high and low level.

3.4.4 SamplersSlurry samplers are provided at the following locations:


Sampler Sampler Type LocationFlotation feed sampler Airlift Conditioning tank

Flotation tail samplers Double Stage cross-cut Flotation cell 5 outlet

Flotation concentrate sampler

Single Stage cross-cut Concentrate thickener underflow pump delivery

CIL tail sampler Airlift CIL tank 7

Detox tail sampler Airlift Detox tank

Final CIL tail sampler Poppet valve Delivery of CIL tails pumps


The airlift sample consists of an airlift with a timer controlled solenoid valve that opens the air supply on a controlled preset frequency and delivers sample into a suitably located container. Sample frequency can be adjusted by changing the solenoid valve timer settings via the SCADA.

The double stage cross cut sampler consists off an electrical motor driven sample cutter that travels through the process stream. Primary sample is delivered into a surge launder to smooth out the flow. The primary sample is passed through a Vezin type secondary sampler. The sample is collected in a sample collection bucket. The reject primary sample from the secondary sampler is fed to the flotation tailings concentrator. Sample frequency can be adjusted by changing the sampler timer settings via the SCADA.


The single stage cross-cut sampler consists of a flexible pipe section normally discharging into a funnel. The pipe is fixed to a pneumatically actuated ram that periodically moves the mouth of the hose over a static sample collection slot in the funnel. The sample is collected via the slot and gravitates into a sample collection bucket. Sample frequency can be adjusted by changing the sampler timer setting at the field mounted sampler control panel.

The final CIL tail sampler consist of an actuated poppet type sampling valve on the CIL tails pump delivery pipeline with a timer controlled solenoid valve that opens the air supply on a controlled preset frequency and delivers sample into a suitably located container. Sample frequency can be adjusted by changing the solenoid valve timer settings via the SCADA.

All samplers are interlocked so they do not operate without process flow.


Manually operated valves are provided as sample points on the ILR and CIL electrowinning cell feed and tail pipelines.

3.4.5 Dust CollectorsThe reverse air pulse to clean the filter media in the crusher dust collector and HPGR & secondary screen dust collector is controlled on a timer supplied by the vendor.

3.4.6 Spillage Sump Pumps


Operation of spillage sump pumps is automatic. The sump is fitted with a switch, which activates at a high level in the sump. The high level signal starts the pump. The pump runs for a preset time after the high level signal is cleared. If the switch indicates the sump remains at a high level after a preset delay, even though the pump has started, an alarm registers at the SCADA.

3.4.7 Positive Displacement PumpsAll positive displacement e.g. helical rotor, diaphragm or peristaltic pumps have pressure relief valves on the pump delivery pipeline located prior to any discharge isolation valves.

3.4.8 Gland Seal Water


On gland-sealed pumps, seal water delivery valves are actuated. The valves are opened and closed as part of the pump start up sequence.

Flow confirmation is provided as a start permissive and low gland water flow alarms when the pump is running but does not trip a running pump. A gland water pressure gauge is installed at each set of pumps. The individual pump gland water lines are equipped with Maric type flow regulation valves.

3.4.9 Safety ShowersThe safety showers are activated by a hand operated valve with a pull chain and equipped with an eye bath activated by a handle and foot pedal.


3.4.10 General MonitoringSelected critical equipment drives are monitored for motor current. They are:

Primary crusher

Secondary crusher

HPGR

Ball mill

Mill pump


Cyclone pump

Detox tank agitator

Several pressure and temperature transmitters are installed to provide data and equipment protection. Many of these instruments are included in vendor packages that provide general alarm conditions to the relevant vendor PLC system.

Also shown are the status of drives (ready, not-ready, running) and advisory alarms on selected drives when shut-down.

3.4.11 Mass Flow Measurement


For control and tonnage accounting purposes at various points in the process, mass flow measurement is provided.

For dry material on conveyors, this is achieved by belt weightometers. All belt weightometers are single strain gauge load cell, dual idler type with span calibration by mass attached to the frame. Weigh class idlers are installed three idlers before and three idlers after the weightometer. The belt weightometers have a local display of instantaneous belt loading and integrated dry tonnage flowrate, as well as totalised dry tons. The dry tonnage flowrate and totalised dry tons are calculated by the PLC and displayed on the SCADA system.


For slurry flows, magnetic flow meters and a nuclear density meters are installed on the relevant pipeline. Instantaneous slurry density and volumetric flow are displayed locally and on the SCADA system. The dry tonnage flowrate and totalised dry tons are calculated by the PLC and displayed on the SCADA system. The instruments are typically installed on a vertical section of pipe at least 10 pipe diameters after and five pipe diameters before any constriction, valve, bend or feature in the pipe that may cause a disturbance in the slurry flow.

3.4.12 ThickenersNuclear density meters are installed on the thickener underflow pump delivery pipelines. The density meter can control the thickener underflow pump variable speed, i.e. slowing the pump if the density drops and speeding up the pump if the density rises.


If the density of underflow slurry drops below the minimum acceptable, e.g. if the thickener feed is interrupted due to a stoppage in the upstream process, the PLC alarms. The SCADA advises the control room operator to close the remotely controlled actuated underflow pump delivery valve feeding the downstream process and open the remotely controlled actuated recycle valve diverting slurry back to the thickener feed. The PLC detects if the thickener is in this recirculation mode for longer than a period of 15 minutes an alarm pops up at the SCADA screen to ensure the control room operator stops flocculant solution addition.

A magnetic flow meter on the delivery line from the underflow pump to the downstream process, is installed after the valves used for diverting underflow slurry back to the thickener feed column. The volumetric flow and nuclear slurry density measurement are integrated in the PLC to provide indication and totalisation of the dry tonnage flowrate to the downstream process.


The thickeners are equipped with “mud-level cone” type interface detectors that warn the control room operator via the SCADA if the bed level is rising so that corrective action can be taken before a sliming condition occurs. Thickener rake torque measurement is displayed and logged for trending on the SCADA system. An increase in solids loading raises the high and high-high torque alarms that activate at the SCADA.

3.4.13 Cranes and HoistsAll powered hoisting equipment, including both travelling cranes and monorail type hoists, are controlled by either hand held cable pendant with two speeds available for both hoisting and travelling or hand held radio frequency remote control keypad (crusher, mill flotation and gold room concentrate hoists).


4 PROCESS PLANT CONTROL PHILOSOPHY

4.1 CrushingRefer to P&ID 1475-P051 Crushing.

The crushing area is generally controlled from the crusher control room. The MCR can only monitor operations in the crushing plant up to the discharge of crushed ore intro the fine ore bin. Equipment is generally started and stopped as part of start-up and shutdown sequences.


The rate of tipping into the ROM bin is a controlled by the visual observation of the loader driver in communication with the crusher operator. A level element in the ROM bin provides and indication of the bin level. At a high level, the crusher operator manually activates a switch to illuminate a red light to advise the loader driver that he may not tip. A high level alarm is provided and a low-low level alarm is interlocked to stop the primary jaw crusher feeder. The low-low level interlock ensures that material cannot normally be tipped into an empty bin and damage the feeder.

The variable speed of the primary jaw crusher feeder is set to match the primary jaw crusher capacity as observed by the crusher operator. A level detection element is installed in the primary jaw crusher feed chute which stops the primary jaw crusher feeder in the event of high level.


A self-cleaning belt magnet is installed at the discharge of crusher product conveyor (CV-001) for tramp metal removal. The magnet is started and stopped as part of the crushing sequence.

A variable speed vibrating feeder delivers ore from the secondary crusher feed bin to the secondary cone crusher. The feeder speed is controlled by a level element in the secondary crusher feed bin. A level element in the crusher feed cavity stops the feeder at a high level.


A high level in the secondary crusher feed bin stops the primary crusher feeder. A high-high level in the secondary crusher feed bin stops the secondary crusher feed bin conveyor. A metal detector is installed on the secondary crusher bin feed conveyor. If crusher magnet 1 fails to remove tramp metal or non-magnetic metal is present, the secondary crusher metal detector activates the secondary crusher feed bin diverter gate in the secondary crusher feed bin, forcing material to bypass the bin by diverting back to the crusher product conveyor for a set period. This period is long enough to ensure any metal detected bypasses the bin. If the position switch on the secondary crusher feed bin diverter gate does not register the gate has moved to the divert position in time, the secondary crusher bin feed conveyor trips.

The secondary cone crusher has an alarm after a certain idling time (e.g. 30 minutes). The control room operator is directed to shut-off the crusher if no feed is available.


The primary jaw crusher has an automated pneumatic grease lubrication system running on a timer. The secondary cone crusher has a low-pressure air seal system to protect the eccentric and drive from dust. The crusher is equipped with a vendor supplied hydraulic positioning system for raising and lowering the main shaft to adjust the crusher gap setting and for tramp relief. An air-cooled lubrication system circulates and cleans oil for the crusher drive.

The dust collection system on the outlet of the primary and secondary crushers and fine ore bin feed conveyor head pulley and the system at the secondary screen and HPGR are started and stopped automatically as part of the crushing sequence.

The fine ore bin feed weightometer installed on the fine ore bin feed conveyor measures and totalises the flowrate of crushed ore from the crushing plant fed to the fine ore bin. The indication can be used by the control room or crusher operator as a guide to adjust the primary


jaw crusher feeder speed to control the feed to the crushing plant. A level element is installed in the fine ore bin feed conveyor head chute which stops the conveyor in the event of a high level in the fine ore bin.


The crusher spillage pump delivers to the stormwater collection pond and the stormwater collection pump delivers decanted water underground for disposal. High level switches in the crusher building and at the stormwater collection pond provide an alarm to warn of flooding.

Ventilation in the crusher building is provided by the crusher area fan. At the entrance for personnel to the building, a green light illuminates while the fan is running and a warning red light illuminates if the fan is stopped.

4.2 Fine Ore Bin, HPGR, Grinding and GravityRefer to P&IDs 1475-P052 Fine Ore Bin & HPGR, 1475-P053 Grinding Gravity Circuit Sheet 1 of 3, 1475-P054 Grinding Gravity Circuit Sheet 2 of 3, 1475-P055 Grinding and 1475-P079 Gravity Circuit Sheet 3 of 3.


4.2.1 Fine Ore Bin & HPGRThe HPGR feed rate is controlled automatically using the variable speed drive of the fine ore bin belt feeder. The fine ore bin reclaim weightometer on the HPGR feed conveyor measures the flowrate of crushed ore from the bin and is used to control the feeder variable speed.

The feed to the fine ore bin will be stopped by interlock at low bin level to prevent material impacting directly on the fine ore bin belt feeder causing damage. The fine ore bin maybe emptied during maintenance. If the bin is re-filled from empty to full without the fine ore bin belt feeder being started bridging may occur. In this case, when the empty bin’s low level alarm condition is removed as filling commences, a timer is initiated. If the fine ore bin belt feeder is not started before expiry of the timer, the feed to the fine ore bin will be stopped by an interlock to the fine ore bin feed conveyor.


An electromagnet (HPGR magnet) is installed on a gantry at the discharge of the fine ore bin belt feeder onto HPGR feed conveyor. The magnet is normally left energised (i.e. switched on). If switched off it must be energised before initiating the HPGR start up sequence. To clean the magnet, the fine ore bin reclaim feeder is stopped and the HPGR magnet hoist is used to move the magnet along the gantry frame to a position adjacent to the conveyor and the magnet power switched off, dropping accumulated metal into a skip for removal. The hoist is used to move the magnet back along the gantry frame to the correct position and the HPGR feed restarted.


Metal detectors are installed on the HPGR feed and mill screen oversize conveyors. If the HPGR magnet fails to remove tramp metal or non-magnetic metal is present, either HPGR metal detector 1 or 2 activates the HPGR diverter gate in the HPGR feed bin, forcing material to bypass the bin to the HPGR bypass bunker for a period long enough to ensure any metal detected bypasses the bin. If the position switch on the HPGR diverter gate does not register the gate has moved to the divert position in time, the HPGR feed and mill screen oversize conveyors trip.


The HPGR is equipped with variable speed electric motors for the rolls. The roll speed is controlled by the level in the HPGR feed bin measured by an ultrasonic level indicator. If the bin fills up, the rolls speed up and vice versa to maintain a constant level in the bin. The HPGR operates under a choke fed condition at all times and the roll speed is kept to the minimum required to satisfy the throughout required while running as slowly as practical to maximise tyre life.


The mill screen oversize weightometer installed on the mill screen oversize conveyor is used to account for mill screen oversize returned to the HPGR feed The sum of the two weightometers is the total HPGR feed rate and can be used to calculate the circulating load. An increase in circulating load indicates poor screening efficiency at the ball mill screen, likely to be due to a blinded screen deck. The mill operator should then investigate and rectify the situation as required. A high level alarm in the HPGR feed bin overrides the normal fine ore bin reclaim weightometer control of the fine ore bin reclaim feeder and reduces the feeder speed to a minimum.

The HPGR is equipped with a dedicated PLC for management of key alarms, trip settings, interlocks, start up, and shut down sequencing for the main and auxiliary drives. All alarms from the vendor PLC control panel are repeated at the SCADA system via the relevant plant PLC. The power, torque, current and speed of the two motors are displayed at the SCADA system.


A level switch is installed in the ball mill screen feed box which stops the mill feed conveyor in the event of a high level caused by a blockage in the ball mill screen feed box.


4.2.2 Grinding and GravityThe ball mill screen underflow and ball mill discharge, via the trommel, flow to the mill pump hopper. There is one operating mill pump, with an installed standby. The mill pump delivers via the jig feed distributor to the three primary jigs operating in parallel. Each pump has actuated valves for isolation of suction, discharge and gland water. The hopper level is measured and is controlled automatically by adjusting the pump variable speed.

Water addition to the grinding and gravity section is sourced from the process water tank via the process water pump.

A flow meter is installed on the water supply to the ball mill screen gold trap and ball mill screen sprays. The desired flowrate is entered manually into the controller at the SCADA and the flowrate controlled by an actuated valve.


A flow meter is also installed on the water supply to the ball mill feed chute. The desired flowrate to provide the required mill discharge slurry density is entered manually into the controller at the SCADA and the flowrate controlled by an actuated valve.

The mill feed chute seal and mill trommel spray water flows are controlled by manually adjusted valves. A master actuated valve on the pipeline supplying mill feed dilution, mill feed chute seal and mill trommel spray water is interlocked to the ball mill drive such that the mill cannot be started unless the valve is open first and the water supply will be closed when the mill is stopped.


Jig hutch water is set during commissioning using the vendor supplied magnetic flow meter at the jig and manually adjusting a water flow control valve at the jig also supplied by the vendor. Hutch water flow can be optimised thereafter by adjusting the valve position. Hutch water flowrate is indicated at the SCADA. The jigs are equipped with their own panel mounted controller to adjust the stroke and frequency of the pulsation.

Mill pump hopper dilution water is controlled by an actuated control valve. The valve position is controlled by the output of the nuclear density meter installed on the mill pump delivery pipeline feeding the jig feed distributor to give a consistent cyclone feed slurry density. Operators check the density of jig feed, mill cyclone overflow, underflow and mill discharge every hour using a Marcy density scale.


Concentrates accumulating in the ball mill screen gold trap are flushed out periodically to a Concentrate Kibble in the goldroom by opening remotely actuated purge valves. The fail close valves are set to open for a short pre-set period and can be opened on a set frequency basis controlled by a timer or on an ad-hoc basis by the operator. The gold trap should be routinely purged prior to a planned plant shutdown.

Concentrates from the jigs are discharged into the spinner feed distributor. Spinner tails are returned to the spinner tails pump hopper. A slurry of coarse solids gravitates from the spinner tails pump hopper to the mill pump hopper. Provision is made to divert the coarse solids slurry to the cyclone pump hopper if required. Fine solids and water overflow the hopper into an overflow compartment and are pumped using the spinner tails pump to the mill screen gold trap to increase feed dilution. A high level overflow on the hopper overflows to the mill pump hopper.


Four spinners are installed in two parallel pairs of spinners in series. Normally the two spinners in each pair operate as a primary and secondary stage device with the first unit’s tail feeding the second unit. The feed valve to the first stage is actuated and closes when the first stage unit is flushing; diverting slurry from the spinner feed distributor directly to the second stage unit until flushing is complete. When the second stage unit is flushing, the actuated intermediate valve closes and diverts the first stage unit tails directly to the mill pump hopper. Spinners are equipped with their own panel mounted controller to allow setting of cycle times and the sequential opening and closing of feed and flushing water valves.


The centrifugal concentrator is located in the mill area. The centrifugal concentrator is controlled by a Falcon “AutoPAC" control system. This is a stand-alone unit mounted near to the centrifugal concentrator and allows setting of key operational parameters such as cycle time. Manipulation of process variables is only possible at the “AutoPAC” system user interface. The SCADA only displays whether the centrifugal concentrator system is healthy and the unit is concentrating, flushing or running in flush inhibit mode.

An actuated knife gate valve is provided on the centrifugal concentrator feed line from the gravity screen underpan. During the normal concentrating cycle, the valve feeding the concentrator is open. For bypass during the concentrate flush cycle the valve is closed and the slurry level backs up in the screen underpan until it reaches the level of the overflow pipe that diverts slurry directly to the centrifugal concentrator tail pipe feeding the cyclone pump hopper. Should the concentrator trip, the valve fails closed in order to bypass it until it can be restarted.


There is one operating cyclone pump, with an installed standby. The pump delivers to the mill cyclone cluster. A duty and a standby cyclone are installed. Each pump has actuated valves for isolation of suction, discharge and gland water.

The cyclone pump hopper level is measured and is controlled automatically by adjusting the pump variable speed. A diaphragm-protected gauge on the cyclone feed distributor measures the cyclone pressure. The cyclone isolation valves are manually opened and closed. A low level alarm in the hopper opens an actuated valve adding process water to the hopper to assist in start up of the circuit and prevent the pump from choking.

A flow meter is also installed on the water supply to the centrifugal concentrator, gravity screen sprays and cyclone pump hopper. The flow meter is not used for control of water addition but is provided for monitoring purposes.


Though the cyclone feed slurry density is ultimately controlled by the water addition to the jig feed slurry at the mill pump hopper, the cyclone feed density is monitored by the control room operator. A nuclear density meter is installed on the cyclone pump delivery pipe line and the measured density is indicated at the SCADA.

A level measurement device is installed in the cyclone underflow launder to warn of a choked mill feed chute. A high level alarm will override the level control on the mill and cyclone pump hoppers and will trip the mill feed conveyor.


Concentrates flushed from the spinners and centrifugal concentrator are delivered to the gravity concentrate surge tank. The tank is equipped with a level measurement device. The level measurement prevents any of the spinners or centrifugal concentrator from flushing concentrates if the tank level is too high. Concentrates are pumped from the tank to the gravity concentrate tank in the goldroom by the gravity concentrate transfer pump. There is one operating pump, with an installed standby. The pump suction and delivery arrangement is a single flexible hose. To change over pumps, a security cleared operator will enter the security cage and change over the suction and delivery lines.


As the flushing of concentrates to the surge tank is an intermittent process, the delivery of the gravity concentrate transfer pump is normally set to recycle to the tank to maintain the concentrate solids in suspension when the tank level is low. After any of the spinners or the centrifugal concentrator flushes a batch of concentrate to the tank and the level in the tank rises, the position of actuated valves on the pump delivery is reset to transfer concentrate slurry to the gravity concentrate tank in the goldroom until the level drops. The PLC inhibits flushing of any of the spinners or the centrifugal concentrator if the gravity concentrate surge tank is at a high level.

Balls are added to the mill every shift by the mill operator. The ball addition rate is manually controlled by the operator to ensure the correct mill power draw is achieved.


Balls are delivered in drums and immediate usage requirements stored near the mill. The drums are emptied manually into the ball kibble and this hoisted to the mill feed chute floor and emptied into the mill feed chute.

Spillage from the grinding and gravity bunded area is pumped to the mill pump hopper by mill spillage pump 1 or 2. The mill hoist is a travelling overhead gantry crane that services the grinding facilities.

4.3 Flotation

4.3.1 Flotation Feed ThickenerRefer to P&ID 1475-P056 Flotation Feed Thickener.


Mill cyclone overflow gravitates to the flotation feed thickener feed box and is mixed with dilute flocculant. Thickener feed slurry gravitates into the thickener feed well. Thickener overflow reports to the process water tank and is recycled by the process water pump to the grinding circuit. Thickener underflow slurry at a controlled density from the flotation feed thickener is pumped to the conditioning tank. A duty and a standby underflow pump are installed. Each flotation feed thickener underflow pump has actuated valves for isolation of suction, discharge and gland water.

Spillage from the flotation feed thickener area is pumped back to the flotation feed thickener feed box by the flotation feed thickener spillage pump.

4.3.2 Flotation


Refer to P&ID 1475-P057 Flotation 1.

The flotation activator, collector are added to the conditioning tank. Frothing agent is added to the first flotation cell. The flotation reagent addition rate is ratio controlled by the integrated dry tonnage flowrate measurement on the flotation feed thickener underflow pump delivery to the conditioning tank. Facilities are provided for the addition of small extra quantities of collector and frother to the feed to second and third banks of cells.


The flotation section consists of rougher cells in three banks in series of one, two and two cells respectively. The concentrate froth launders gravitate to the flotation concentrate pump (one duty/one standby). Concentrate is pumped to the concentrate thickener. The flotation concentrate pumps are fixed speed. The flotation cell levels are controlled by actuated pinch valves located in the discharge of the cell banks. Flotation cell 1, 3 and 5 levels are measured by an ultrasonic level probe and used to adjust the position of the valve on the cell outlet.


Flotation tails from the final cell gravitate via the flotation tails primary sampler into the flotation tail pump hopper. The flotation tail pumps (one duty/one standby) pump to either the sand cyclone or directly to the flotation tail thickener feed box depending on whether the sand cyclone is online or not. The primary flotation tails sample passes through the flotation tails secondary sampler and into the flotation tail concentrator. The concentrator is installed to sample the flotation tail slurry and detect any gravity recoverable free gold particles to identify any deficiency in the operation of the gravity gold recovery section. Concentrator tails gravitate to the flotation tails sampler transfer sump pump and are pumped to the flotation tails thickener feed box. Concentrate is collected and transferred by hand to the plant laboratory.

The flotation tail pump hopper level is measured and is controlled automatically by adjusting the flotation tail pump speed. Each pump has actuated valves for isolation of suction, discharge and gland water.


The low-pressure airflow to the individual flotation cells is regulated by a vendor supplied flow control valve and flow meter at each flotation cell.

Spillage from the flotation bunded area is hosed to the flotation spillage pump and pumped to the conditioning tank.

4.3.3 Concentrate ThickenerRefer to P&ID 1475-P058 Concentrate thickener.


Flotation concentrate slurry is pumped to the concentrate thickener and is mixed with dilute flocculant in the thickener feed well. Overflow reports to the process water tank. Underflow from the thickener is pumped by the concentrate thickener underflow pump to the trash screen. A duty and a standby underflow pump are installed. Each underflow pump has actuated valves for isolation of suction and discharge.

Spillage from the concentrate thickener area is pumped back to the concentrate thickener by the flotation concentrate spillage pump.

4.3.4 Flotation TailingsRefer to P&ID 1475-P059 Flotation Tailings Sheet 1 and 1475-P060 Flotation Tailings Sheet 2.


If the sand cyclone is offline, flotation tails slurry is pumped directly to the flotation tail thickener feed box and is mixed with dilute flocculant. If the sand cyclone is online, flotation tails slurry is pumped to the sand cyclone. Fines are removed in the cyclone overflow and coarse sand discharges from the cyclone underflow to the sand pump hopper and is pumped to the flotation tailings storage facility. Sand cyclone overflow gravitates to the flotation tail thickener feed box and is mixed with dilute flocculant.

Thickener feed gravitates into the thickener feed well. Thickener overflow reports to the process water tank. Underflow from the flotation tail thickener is pumped by the flotation tail thickener underflow pump to either the east flotation tailings storage facility. A duty and a standby underflow pump are installed. Each underflow pump has actuated valves for isolation of suction, discharge and gland water.


Sand cyclone underflow slurry is diluted with process water in the sand pump hopper. Diluted sand slurry is pumped to a dedicated sector of the east flotation tailings storage facility. A duty and a standby pump set are installed. Each sand pump set has actuated valves for isolation of suction, discharge and gland water. The hopper level is measured and is controlled automatically by adjusting the second stage pump variable speed. Hopper dilution water is controlled by an actuated control valve. The valve position is controlled by the output of the nuclear density meter installed on the sand pump delivery pipeline. The valve position control is overridden at low pump hopper level to ensure the delivery pipeline flushes clear.

Three options are available for alternate operation of the flotation tailings disposal system.


Option 1 is the normal design case with the sand plant and flotation tails thickener online. The single duty flotation tailings thickener underflow pump and one tailings pipeline are used as well as the single duty 2 stage sand pump installation and one sand pipeline are used .

Under Option 2, if the sand plant is offline and the thickener online, the sand cyclone feed valve (XV4040) is closed and the bypass valve (XV4041) opened in. The flotation tailings thickener is sized to accept the higher feed rate as the unclassified flotation tailings have higher settling rate. In order to process the increased underflow slurry volume through the thickener, a parallel tailings thickener underflow pumping system is used. Both of the flotation tail thickener underflow pumps are operated in parallel delivering separately via both tailings pipelines.


Under Option 3, if both the sand plant and thickener are offline, due to the volume of dilute slurry from the flotation tailings pumps the installed tails thickener underflow pumps will have insufficient capacity for the unthickened flotation tailings slurry at the design plant feed rate. The sand cyclone feed valve (XV4040) is closed and the bypass valve (XV4041) opened. To achieve the thickener bypass, a tee section will be added into the thickener feed pipe prior to the thickener feed box. This will feed the tailings thickener underflow pump suctions. A parallel tailings thickener underflow pumping system is used with both of the flotation tail thickener underflow pumps operating in parallel delivering separately via both tailings pipelines. A reduced plant feedrate of 44 t/h is adopted to reduce the slurry volume pumped.


Water is reclaimed from the flotation tailings storage facility by a flotation tail decant pump. Decant water is returned to the process water tank. A thermal flow switch is installed on the decant pump delivery. If a no flow situation is detected by the switch, due to the process water tank being full and the outlet float valve being closed, or the TSF being dry, the switch stops the decant pump. The switch is linked to a timer and the pump will restart after a 20 minute delay.

Seepage water from the flotation tails storage facilities is collected in trenches. A pump is located at the facility and seepage water pumped back onto the flotation tailings storage facility by a seepage pump. The pumps are started and stopped automatically by a level switch in the seepage trench.


Spillage from the flotation tails thickener bunded area is hosed to the flotation tail thickener spillage pump and pumped back to the flotation tail thickener feed box. If the flotation tail thickener is to be bypassed in the event of a breakdown, the delivery of the flotation tail pump can be connected temporarily to the suction of the flotation tail thickener underflow pump.

4.3.5 GoldroomThe goldroom is manned during dayshifts only and all equipment is started and stopped locally.

4.3.6 Shaking TablesRefer to P&ID 1475-P061 goldroom - Gravity Area.


Gravity concentrate from the ball mill screen gold trap is discharged into a kibble located above the gravity concentrate screen. The contents are fed to the gravity concentrate screen. The screen has a 4mm aperture. Screen oversize and undersize is collected in concentrate kibbles. When the goldroom is manned, the kibble containing the screen undersize is emptied into the oversize concentrate transfer pump tank. The kibble containing the screen oversize is emptied onto the concentrate sorting table where the goldroom operators may remove oversize gold nuggets by a combination of hand sorting and use of a hand held metal detector. Sorted concentrate is swept into a kibble and charged into the oversize concentrate bin. Concentrates are reclaimed from the bin by the oversize concentrate feeder onto the oversize concentrate sorting belt where any remaining observable nuggets can be recovered by the goldroom operator. The oversize concentrate feeder has a variable speed set by the goldroom operator. The oversize concentrate sorting belt delivers into the concentrate roll crusher. Crushed


concentrate, nominally minus 1 mm, is discharged into the gold room spinner wetting box. Dilution water is added and the wetting box discharges into the goldroom gravity spinner. Concentrate is collected for drying and smelting and tailings gravitate to the oversize concentrate transfer pump. The pump delivers tailings to goldroom fine screen with the gravity concentrates from the spinners and centrifugal concentrator from the gravity concentrate tank fed by the concentrate rotary feeder. The feeder has a variable speed set by the goldroom operator.


Goldroom fine screen oversize gravitates to the oversize concentrate bin and undersize to the concentrate jig. Jig tails are discharged to the gravity middlings pump. Jig concentrates are fed onto shaking table 1. Shaking table 1 middlings are fed to shaking table 2. Concentrates from both tables are collected in buckets, excess water decanted and placed in trays in the calcine oven for drying. Tailings from both shaking tables are combined with jig tails at the gravity middlings pump and pumped to the ILR feed cone. The concentrate jig is equipped with a 1 mm screen. Any coarse (i.e. +1 mm) concentrate accumulating in the jig is removed, collected in a kibble and emptied into the oversize concentrate bin to be crushed and returned to the circuit.

Water is supplied to the jig and shaking tables from the goldroom water tank. The level of water in the tank is controlled by a float valve to give a constant steady head of water. Water is supplied to the gold room gold room spinner wetting box directly from the raw water supply.


The gravity concentrate tabling area is bunded to prevent escape of spilt high-grade concentrates. The goldroom spillage pump is installed to return spilt high grade concentrates to the gravity concentrate tank.

4.3.7 Goldroom - SmeltingRefer to P&ID 1475-P062 Goldroom - Smelting.

Electrowinning gold sludge from the pan filter is loaded into trays and the trays lifted by hand into the calcine oven. The oven temperature is controlled by the vendor supplied oven thermostat.


The required amount of fluxing chemicals (silica, borax, sodium nitrate, and soda ash) are weighed on the flux balance then loaded by hand from the flux bin and mixed with the weighed amount of calcine in the flux mixer. The mixed furnace charge is added by hand to the smelting furnace.

Slag is poured as required prior to pouring Doré bullion. Doré is cast into bar moulds. Bars are water quenched and then cleaned manually with needle guns at the bar cleaning table followed by stamping and packaging and storage in the vault before shipment for refining. Slag is initially re-melted and final slag is returned to the ball mill.


The smelting furnace is covered by the furnace hood. Smelt furnace fumes along with fumes from the calcine oven flue and electrowinning cells are ducted to the goldroom scrubber by the goldroom scrubber fan. The wet scrubber system uses a weak sodium hydroxide solution circulated through the tower by the goldroom scrubber pump to remove contaminants. A bleed stream from the scrubber is pumped to the cyanide detoxification section and scrubbed fume is vented via the goldroom scrubber stack. The scrubber is controlled by a vendor supplied PLC that interfaces to the plant PLC system.

The goldroom is located inside a building fitted with secured entrances, surveillance and alarm systems. An upper operating floor is provided for the electrowinning cells, while the lower floor is used for filtration, calcination, smelting, bullion handling, vault and office.


The goldroom is monitored by a video surveillance system incorporating sufficient CCTV cameras located and cabled to the mine security office for recording. The cameras cover all access doors, the calcine oven door, smelt furnace and vault door, electrowinning cells and vacuum filter.

An alarm system is installed in the goldroom area with passive motion detection, door proximity switches and system arming/disarming keypad transmitting to the mine security offices. The alarm system is armed whenever the goldroom is vacated. Security checks of staff working in the goldroom are made using handheld metal detectors.

4.4 Reagents and Consumables


Reagent makeup is performed by operators on day shift and the design of these systems is based on this philosophy.

4.4.1 Collector and FrotherRefer to P&ID 1475-P063 Reagents & Consumables Sheet 1 of 4.

Dithio-phosphate collector and frother are delivered in bulk-a-boxes. The handling and storage is identical for both reagents.


Both bulk-a-boxes are connected to stand pipes. The stand pipe provides a reserve while an empty bulk-a-box is changed. Duty and standby variable speed double diaphragm dosing pumps connected to the stand pipes meter the reagent additions from the collector and frother standpipes tanks to the conditioning tank and first flotation cell respectively. The pump speeds are controlled by the flotation feed thickener underflow mass flow measurement. A low level switch is installed in both stand pipes to indicate if the bulk-a-box is empty and alarms at the SCADA screen if the level is low.

Spillage from the collector and frother storage area is hosed to the flotation bunded area.

4.4.2 Copper SulphateRefer to P&ID 1475-P066 Reagents & Consumables Sheet 4 of 4.


Copper sulphate pentahydrate (CuSO4.5H2O) is delivered in 25 kg bags and is dissolved in raw water to produce a solution at 20% w/v for use at flotation and cyanide detoxification. Usage is a relatively small volume so make-up and storage use the same tank. The tank is split by a vertical plate into the main make up and storage compartment and a reserve compartment. A level switch is installed in both sections of the tank and a low level alarms at the SCADA.

Normally copper sulphate solution is dosed from the main section of the tank. Make up of copper sulphate is a manual operation, initiated by the operator when the tank is close to empty. When a fresh batch of solution is being made up, the dosing pump suction manifold valve from the main compartment of the tank is closed and the valve from the reserve compartment opened.


The operator then opens a manual valve to add fresh water partially filling the main section of the tank. The water valve is then closed and the copper sulphate agitator started by the operator who can then add sufficient bags of copper sulphate using the bag breaker. On completion of mixing, the agitator maybe stopped. The operator opens a valve on a balancing line between the two compartments to refill the now partially empty reserve compartment. The suction manifold valve from the main section of the tank is reopened and the suction valve from the reserve compartment closed.


Three variable speed double-diaphragm dosing pumps are installed. Normally one pumps to the conditioning tank and another to the detox tank, with a common standby. The copper sulphate addition rate to flotation is ratio controlled by the integrated dry tonnage flowrate measurement on the flotation feed thickener underflow pump delivery to the conditioning tank. Flow is controlled by varying the speed of copper sulphate dosing pump A or the common standby pump.

The flow rate of copper sulphate to the detox tank is controlled by varying the speed of the copper sulphate dosing pump C or the common standby pump. The pump speed is ratio controlled to the CIL tails volumetric flowrate measured by a magnetic flow meter on the CIL tails line.


Spillage from the copper sulphate make up area is pumped to the detox tank by reagents spillage pump 1.


4.4.3 FlocculantRefer to P&ID 1475-P064 Reagents & Consumables Sheet 2 of 4.

Flocculant powder is delivered in bulk by road tanker and pneumatically offloaded into the storage vessel. Dry powder is dissolved in raw water to produce a solution at 0.2 % w/w for subsequent dilution and use at the thickeners.

Dissolution of flocculant is a fully automatic operation, initiated by a signal from a low level switch in the flocculant tank. The flocculant preparation plant is a vendor supplied package. The operator is required to maintain an adequate amount of dry flocculant in the feed hopper. A low level signal in the feed hopper alerts the operator.


The batch controller of the flocculant make-up system automatically controls the addition of water, transfer of dry flocculant to the dispersion head, the mixing time for solution aging, and the transfer to the flocculant tank. A single “general fault” alarm notifies the operator to check the system.

The flocculant tank has a level switch, which initiates mixing and transfer and a level measurement element, with a low-low level alarm to notify the operator of problems, and protect the dosing pumps from running dry.


The operator must ensure that the hopper contains dry flocculant powder, the water supply isolating valve is open and check that there is sufficient water pressure to the Auto Jet Wet by observing the pressure gauge reading and ensure the power supply is on and the Duty Selector Switch is set to "AUTO" mode. For further details, refer to the Ciba Specialty Chemicals Operating, Maintenance & Installation Manual.

A dedicated flocculant dosing pump is provided for flocculant addition at each thickener. A common standby is provided for the pumps delivering to the flotation feed and flotation tail thickeners. A duty and a dedicated standby pump are provided for flocculant addition to the concentrate thickener.


Strong flocculant solution (0.2%) is pumped into inline mixers, where process water is added to the flocculant solution to dilute the concentration to 0.02% to ensure better dispersion in the slurry stream. Each thickener’s flocculant pump delivers flocculant to a dedicated inline mixer. The pumps are equipped with variable speed drives to allow the flocculant solution dosage to be adjusted manually. Dilution is controlled by the operator. The operator adjusts the flocculant dilution water valve and checks by inspection of rotameters, the flow of water and flocculant respectively until the correct degree of dilution is achieved. Manual valve controlled addition points are provided at each thickener feed pipe to ensure adequate dispersion of dilute flocculant solution.

Flocculant spillage from the flocculant make up area is hosed to the flocculant spillage pump and pumped to the flotation tailings thickener overflow launder.


4.4.4 Sodium CyanideRefer to P&ID 1475-P065 Reagents & Consumables Sheet 3 of 4.

Sodium cyanide is delivered as briquettes in bulk bags packed into boxes. Sodium cyanide solution make-up and storage use the same tank. The tank is split by a vertical plate into the main make up/storage compartment and a reserve compartment.

Normally sodium cyanide solution is dosed from the main section of the tank. Make up of sodium cyanide solution is a manual operation, initiated by the operator when the tank is close to empty. While a fresh batch of solution is made up, the dosing pump suction manifold valve from the main compartment of the tank is closed and the valve from the reserve compartment opened.


The main section of the tank is partially filled with raw water via an actuated valve and briquettes are loaded into a cage located in the main compartment of the tank. The tank is topped up with raw water. The cyanide agitator is started to dissolve the briquettes to make up a 20% solution.

On completion of mixing, the agitator is stopped. The suction manifold valve from the main section of the tank is reopened to balance the level in the main section and now partially empty reserve compartment. The valve from the reserve compartment is then closed.

Sodium cyanide solution is pumped through a ring main by the cyanide pumps (one operating, one standby) to the CIL, elution tank and ILR and returned to the cyanide tank. Line pressure is maintained by a manually operated diaphragm valve. The ring main return discharges into the reserve compartment of the tank to ensure it is always full.


Cyanide solution is dosed to CIL tank 1 from an actuated flow control valve on the ringmain pipeline. The position of the control valve is set by a cascade loop from the concentrate thickener underflow mass flow system to the CIL cyanide addition flowmeter located upstream of the flow control valve.

If cyanide is required at the elution tank, it is added by opening via remotely controlled actuated valve from the cyanide ringmain. The required volume of cyanide solution flowing to the tank is totalised by a flow meter and the remotely controlled actuated valve closed. Cyanide addition to the ILR from the ringmain is controlled by the ILR PLC.


The cyanide tank is equipped with level measurement devices indicating at the SCADA in both compartments. A high level alarm in the main compartment is interlocked to the water addition valve and a low level alarms at the SCADA screen. A low-low level in the main compartment or low level in the reserve compartment will trip the cyanide pump.

A duplex strainer is installed on the suction of the cyanide pumps.

Spillage from the cyanide make up tank bunded area is pumped to CIL tank 1 by reagents spillage pump 2. Reagent hoist 2 services the cyanide make up facilities.

4.4.5 Sodium HydroxideRefer to P&ID 1475-P065 Reagents & Consumables Sheet 3 of 4.


Sodium hydroxide is received in bulk-a-boxes, at a solution strength of 50% w/v. The bulk-a-box functions as a storage tank and is connected to a stand pipe. The stand pipe provides a reserve while an empty bulk-a-box is changed. A low level switch is installed in the stand pipe to indicate if the bulk-a-box is empty and alarms at the SCADA screen if the level is low. A low-low level switch trips the sodium hydroxide pumps to prevent them running dry.

Two double-diaphragm dosing pumps are installed.

Sodium hydroxide pump A is a fixed speed pump and delivers to either the elution or the acid wash tanks. The delivery valve to either tank is opened and the other valve closed manually. The pump is normally left in “Maintenance” mode and started and stopped in the field. The start button initiates a timer so that if the pump is not stopped manually before the timer expires the pump will stop to prevent accidental overdosing.


Sodium hydroxide pump B delivers to the ILR and goldroom scrubber via a ringmain returning to the stand pipe. Addition of sodium hydroxide from the ringmain to the ILR and goldroom scrubber is controlled by vendor supplied actuated valves on the respective equipment.

Sodium hydroxide spillage from the bulk-a-box laydown area is hosed into the CIL bunded area for disposal using the CIL spillage pump. Drainage from the sodium hydroxide pipelines is piped directly to the CIL spillage pump sump.

4.4.6 Hydrochloric AcidRefer to P&ID 1475-P065 Reagents & Consumables Sheet 3 of 4.


Hydrochloric acid is received in a bulk-a-box at 33% w/w strength. The bulk-a-box functions as a storage tank and is connected to a stand pipe. The stand pipe provides a reserve while an empty bulk-a-box is changed. A low level switch is installed in the stand pipe to indicate if the bulk-a-box is empty and alarms at the SCADA screen if the level is low.

The hydrochloric acid offload pump is a fixed speed pump and delivers to the acid wash tank. The pump is normally left in “Maintenance” mode and started and stopped in the field. The start button initiates a timer so that if the pump is not stopped manually before the timer expires the pump will stop to prevent accidental overdosing.

Acid spillage from the laydown area is hosed to a spillage sump. A pneumatically operated diaphragm pump (supplied by BML) will be installed to dispose of spillage.


4.4.7 SMBSRefer to P&ID 1475-P067 Reagents & Consumables Sheet 4 of 4.

Sodium metabisulphite (SMBS) is delivered in 1000 kg bags and is dissolved in raw water to produce a solution at 20% w/v for use at cyanide detoxification. SMBS solution make-up and storage use the same tank. The tank is split by a vertical plate into the main make up and storage compartment and a reserve compartment.

Normally SMBS solution is dosed from the main section of the tank. Make up of SMBS solution is a manual operation, initiated by the operator when the tank is close to empty. While a fresh batch of solution is made up, the dosing pump suction manifold valve from the main compartment of the tank is closed and the valve from the reserve compartment opened.


The main section of the tank is partially filled with raw water via an actuated valve. The valve is then closed and the SMBS agitator started by the operator who can then add a bag of SMBS using the bag breaker. On completion of mixing, the agitator is stopped. The operator reopens the water filling valve to fill the main compartment.

The suction manifold valve from the main section of the tank is reopened to balance the level in the main section and now partially empty reserve compartment. The valve from the reserve compartment is then closed.


The SMBS tank is equipped with a level measurement device indicating at the SCADA in both the compartments. A high level alarm in the main compartment is interlocked to the water addition valve. A low level in either compartment will alarm at the SCADA. A low-low level in the main compartment or low level in the reserve compartment is interlocked to trip the SMBS pump.

A duplex strainer is installed on the suction of the SMBS pumps.

The variable speed SMBS pumps (one duty/one standby) deliver solution as required to the detox tank. The flow rate of SMBS to the detox tank is controlled by varying the speed of the SMBS pump. The pump speed is ratio controlled to the CIL tails volumetric flowrate measured by a magnetic flow meter on the CIL tails pump delivery line.


Spillage from the SMBS make up area is pumped to the detox tank by reagents spillage pump 1. Reagent hoist 1 services the SMBS make up facilities.

4.4.8 LimeRefer to P&ID 1475-P066 Reagents & Consumables Sheet 4 of 4.

Hydrated lime is delivered by road tanker and pneumatically off-loaded into the lime silo. The silo is equipped with a dust collector. The dust collector is cleaned by a reverse pulse of air when a high pressure differential is detected over the bag filter.

Lime powder is slurried in the agitated lime tank and pumped via ringmain to the CIL and detox tank by the lime pump (one duty/one standby). A diaphragm valve on the return line is used to provide adequate pressure in the ringmain circulation line.


Lime slurry is dosed to the CIL at the trash screen underflow and at the detox tank from actuated pulsing control valves on the ringmain main pipeline.

The lime tank is equipped with an ultrasonic level measurement element. The level of the tank will drop as lime slurry is dosed to the CIL and detox tank. At a low level set-point, the actuated water addition valve is opened to refill the lime tank and the lime silo vibrated fluidiser and lime feeder is started. At a high level set-point, the actuated water addition valve is closed and the fluidiser and feeder stopped.

A “general fault” alarm notifies the operator to check the lime system.

Spillage from the lime make up area is pumped to the detox tank by reagents spillage pump 1.

4.5 Servicesdocument.doc Page 108

4.5.1 Raw & Potable WaterRefer to P&ID 1475-P067 Services - Water Sheet 1.

Fresh water is delivered from the Bendigo water supply to the potable water tank via the potable water jockey pump.

Water gravitates to the safety showers from the elevated potable water tank. In the event of a plant power failure, the safety showers are assured a limited volume of water feeding them under pressure. The potable water jockey pump is installed to boost the available water supply pressure to fill the potable water tank. A thermal flow switch is installed on the pump delivery. If a no flow situation is detected by the switch (due to the potable water tank being full and the outlet float valve being closed) the switch stops the pump. The switch is linked to a timer and the pump will restart after a 30-minute delay.


The potable water tank is equipped with a mechanical level indicator device.

Fresh water is delivered from the Bendigo water supply to the raw water tank. Water addition is controlled by a float valve. The tank is equipped with a hydrostatic level measurement device and a low level alarms at the SCADA.

The raw water pump (one duty/one standby) distributes water to reagent make-up, the ILR, acid wash, elution and tabling in the goldroom from the raw water tank.

The gland water tank is supplied from the mine water supply (underground pumping). Water addition is controlled by a float valve. The tank is interconnected to the raw water tank, which acts as a back-up water supply and is equipped with a level measurement element.


A low level in the raw and gland water tanks alarms at the SCADA and trips the HPGR feed conveyor.

Gland water is provided as gland seal water to several pumps. Two gland water pumps (duty/standby) are provided, drawing from the gland water tank.

Gland water pressure is monitored locally with a pressure gauge and pressure transducer indicating at the SCADA. A low pressure will alarm at the SCADA and a low-low pressure will trip the HPGR feed conveyor. A relief valve is provided to avoid over-pressuring the gland water main, returning to the tank.

4.5.2 Process WaterRefer to P&ID 1475-P068 Services - Water Sheet 2.


The process water tank is supplied with water recycled from the overflows of the flotation feed thickener, concentrate thickener and flotation tail thickeners, return decant water from the Flotation Tails Storage facilities and make-up water from the mine water supply (underground pumping). The addition of decant and make-up water from the mine water supply is controlled by float valves in the tank. Water sources entering the tank are delivered into the connecting process water stand pipe to minimise sanding of the tank from suspended solids in the thickener overflow streams.

The process water tank is equipped with a hydrostatic level measurement device. A low level alarms at the SCADA and a low-low level will then trip the HPGR feed conveyor.


The CIL water tank is supplied with return decant water from the CIL tails storage facility, and make-up water from the mine water supply. The water in the CIL water tank is used as spray and dilution water at the trash screen, loaded carbon screen and CIL tail screen.

The addition of decant and make-up water from the mine water supply is controlled by float valves in the tank. The CIL water tank is equipped with a hydrostatic level measurement device. A low level in the tank alarms at the SCADA.

The transfer water pump is started and stopped by the operator as required. The level in the transfer water tank is topped up as required by opening a manual valve on the Bendigo water supply line.


If contaminated transfer water is to be disposed of the operator closes the delivery line valve to elution area and opens the recycle valve on the delivery back into the transfer water tank and a bleed valve feeding a small amount of contaminated water to the carbon safety screen feed box and starts the pump. The flow of contaminated water to disposal at the carbon safety screen feed box is controlled manually using the bleed valve.

4.5.3 AirRefer to P&ID 1475-P069 Services - Air.

Duty and standby low-pressure air flotation blowers supply the flotation cells. A local pressure gauge indicator and a transducer indicating at the SCADA are fitted on the low-pressure air main.


Compressor 1 and 2 operate in lead/lag mode and provide high-pressure compressed air for general distribution. Air compressors are rotary screw type complete with vendor controller package, which senses load and starts the second unit or puts the compressor on idle, as required.

All high-pressure compressed air is filtered and dried to produce instrument quality air. All compressed air is filtered using a “Class B” grade filter element in instrument air filter 1 and dried to a 3 degree Celsius dew point using the refrigerant type air dryer. Dry air is filtered using a “Class C” grade filter element in instrument air filter 2 and stored in the plant air receiver then distributed to the plant. Duty and standby air filters are installed. An extra mill air receiver is installed at the mill area to ensure a reliable compressed air supply is available for the mill and jigs.


Air filters are equipped with their own vendor supplied high differential pressure indication to warn when the filter cartridge element is blocked. Each air receiver is equipped with a pressure gauge and pressure transducer indicating at the SCADA.

Compressed air is used for pneumatic tools, chute diverters, and valve and dart plug actuation. Service points are provided throughout the plant.

The CIL LP air blower provides low pressure air that is used for airlifts and interstage screens. Plant air (high pressure) can be used for additional CIL LP air if required.

Oxygen is delivered in liquid form by road tanker and off-loaded into a bulk liquid storage vessel equipped with a vaporising system. The bulk oxygen supply system feeds a plant reticulation system that supplies oxygen to the CIL and detox tanks. The oxygen system includes a tank pressure and discharge pressure control system and tank level and pressure indicators.


4.5.4 OtherUncontaminated plant site run-off is collected in the stormwater collection pond. Collected run-off water can be pumped either to the process water tank or to underground using the stormwater collection pump.

4.6 Gravity Concentrate LeachingRefer to P&ID 1475-P070 Gravity Concentrate Leaching.

The ILR has its own dedicated vendor supplied PLC, which will control all of the ILR integral operations.


Shaking table tails from the goldroom are pumped to the ILR feed cone and excess water overflows to the process water tank.

Settled concentrate slurry drains from the ILR feed cone into the ILR drum. The feed cone de-waters the feed by a load cell and pinch valve combined in a PID timer loop. The load cell measures the mass in the cone and a timer circuit opens and shuts the feed valve to feed the desired flow rate into the ILR drum.


The fresh reagents and return barren solution from the electrowinning circuit are added at the feed. The drum rotates around a horizontal axis. The drum is rotated only fast enough to ensure fresh solution is mixed through the solids. The drum inlet and outlet are set to create a low angle of repose across the drum. The solids are agitated only enough to keep the mass moving from feed to outlet. A set of internal baffles allows movement of solids through the drum but inhibits short-circuiting and helps to hold very coarse gold particles back.

Solution passes through at a controlled rate. The solution and solids pass through at rates independent to each other. This enables the equivalent of a low leach density to be achieved. The low density leach allows high levels of fresh reagent to be passed through the solids.


Solids and solution pass out of the drum and into the ILR pump hopper. ILR pump transfers the slurry to the ILR cyclone. Cyclone underflow drops into the ILR thickener. The ILR thickener underflow reports to the trash screen feed box. The ILR thickener de-waters the tails by a load cell and pinch valve combined in a PID timer loop. The load cell measures the mass in the thickener cone and a timer circuit opens and shuts the feed valve to feed the desired flow rate into the ILR drum.

Cyclone overflow gravitates to the ILR clarifier. The clarifier removes fine suspended solids that gravitate back to the ILR pump hopper. The clarified solution overflowing the ILR clarifier gravitates to the ILR electrowinning cell. The cell tail solution gravitates to the ILR cell tail pump hopper. The ILR cell tail pump (one duty/one standby) pumps the low-grade cell tail solution to the ILR thickener. Therefore diluting the solution gold grade in the ILR tail slurry discharged from the ILR thickener.


The ILR solution tank is equipped with a level element that controls the speed of the ILR pump.

Sodium hydroxide solution for pH control is added to the ILR solution tank. A pH probe is located in the ILR clarifier and controls an actuated valve that adds sodium hydroxide from the ring main. Cyanide addition is ratio controlled from the ILR drum solids feedrate from the ILR feed cone. The output of the control loop controls the position of the cyanide dosing valve from the ring main. Water addition to the circuit is controlled via a level element in the ILR solution tank that controls the opening and closing of the water make up valve on the CIL spray water main.

Flocculant solution is added to the ILR pump hopper and ILR thickener from a dosing tank supplied by Gekko located at the ILR. The dosing tank is filled by the operator daily from the flotation feed thickener dilute flocculant solution pipeline.


Concentrate thickener underflow slurry is pumped via flotation concentrate sampler to the trash screen feed box. At the trash screen, material such as grit, woodchips, fibres, wire and plastic, that would otherwise choke CIL interstage screens and contaminate loaded carbon recovered from the CIL tanks, is removed. The trash screen underflow is pumped into CIL tank 1. The screen spray water is manually controlled to achieve the required CIL slurry density.

Trash screen oversize reports to the trash basket. The basket is equipped with wedge wire mesh panels to allow excess water to drain away, retaining the trash. The basket can be removed with a forklift or hoisted with a crane and emptied. The empty basket can then be replaced.


Lime slurry is added to the trash screen underpan by a pulsing valve on the lime ringmain pipe. A pH meter is installed in CIL tank 1. The output of the pH meter is used to control the valve pulse frequency.

The ILR may not operate when the trash screen or trash screen underflow pump is stopped as ILR tails would blind the screen or overflow the trash screen underflow hopper.

4.7 Flotation Concentrate LeachingRefer to P&IDs 1475-P071 Flotation Concentrate Leaching 1 and 1475-P072 Flotation Concentrate Leaching 2.


Sodium cyanide solution is added to the feed to CIL tank 1 from the cyanide ringmain by a control valve into the first CIL tank. The position of the control valve is set by a cascade loop from the concentrate thickener underflow mass flow system to the CIL cyanide addition flowmeter located upstream of the flow control valve.

Manually operated cyanide “spiking” valves are provided to dose extra sodium cyanide solution, and lime slurry from the ringmain pipelines to CIL tanks 1, 2, 3 and 4.

CIL tanks are each equipped with a hollow shaft agitators. Oxygen can be sparged into the any of the CIL tanks down the agitator shaft. Oxygen flow indication is provided in the field using rotameters with provision for manual adjustment by needle valves.


CIL tanks are equipped with an air swept in-tank screen for carbon retention. Each in-tank screen is formed from stainless steel wedge-wire. The screens are serviced by the flotation hoist. A spare screen is provided so that when a screen is removed for cleaning, it is replaced by the spare screen. If a CIL tank is to be taken offline for maintenance, a manually operated knifegate valve is used to close the feed to the pipe feeding the selected tank from the upstream tank interstage screen outlet and the knifegate valve feeding the next tank downstream is opened.

The recovery of loaded carbon from the CIL and correction of carbon concentrations in each CIL tank is carried out by the operator every shift. Carbon recovery to the Carbon Stripping section is undertaken from the first CIL tank using an airlift. Loaded carbon is cleaned and dewatered by screening over the loaded carbon screen. Loaded carbon gravitates into the acid wash column. Screen underflow slurry gravitates back to CIL tank 1.


Interstage carbon transfers are carried out using airlifts. The operator checks the carbon inventory in CIL tank 1 and 2 and transfers carbon as required to obtain the desired carbon concentration in CIL tank 1. Alternatively, the operator proceeds to the next CIL tank downstream if no transfer is required. After transfer, the operator checks carbon concentration in the tanks and proceeds to the next tank downstream.

When a CIL tank is off-line for maintenance, operators must temporarily connect flexible piping in order to perform interstage carbon transfer across the bypassed stage.

Slurry discharged from the final stage CIL tank gravitates to the cyanide detoxification tank.

A detector is provided on the CIL tank top floor level for monitoring of hydrogen cyanide gas with local buzzer or horn alarms and SCADA alarms in case of high levels.


A laboratory is provided for CIL operators to check slurry densities, pH, and dissolved oxygen (DO) levels and perform titrations to check reagent levels and prepare samples for the assay laboratory. Manually taken slurry samples from the tanks are used to check the slurry density using a Marcy scale. Manual samples are used to check carbon concentrations. Slurry samples are taken from selected CIL tanks every 2 hours, filtered, the solution titrated for sodium cyanide, and the slurry pH measured using a pH meter. Action can then be taken to increase or decrease cyanide and pH modifier addition as needed.

The CIL spillage pump delivers to the spillage from the CIL bunded area back to the CIL tank 1.

4.8 Carbon Stripping


Carbon stripping consists of an ambient acid wash and pressure Zadra elution system and a horizontal carbon regeneration kiln. Gold recovery from pregnant eluate is achieved in a single electrowinning cell. The eluted, barren carbon is reactivated through a horizontal gas fired carbon reactivation kiln before being returned to the CIL.

The acid wash and elution procedures consist of a number of manually controlled procedures that require minimal operator intervention between steps. Procedures are paused at critical points to provide opportunity for monitoring, sampling and selection of stripped carbon discharge location.

The carbon stripping system is sized to handle a 0.5 tonne batch of loaded carbon. The design requirement is to treat five batches every week although this can be increased or diminished depending on plant operating requirements.


4.8.1 Acid WashRefer to P&ID 1475-P073 Acid Wash.

The carbon in the acid wash column is rinsed with raw water and then acid washed to remove calcium carbonate fouling by pumping dilute acid solution (~3% HCl) from the acid wash tank through the column and back to the acid wash tank using the acid wash pump. The acid wash strainers (one duty/one standby) are installed on the outlet of the column to retain any carbon particles carried out of the column by the acid wash flow.

The acid wash spillage pump is installed in the acid wash area. Acidic spillage is pumped to the acid wash tank.


On completion of the acid wash, the carbon in the column is rinsed to remove residual chlorides and avoid the possible generation of hydrogen cyanide gas during elution. The rinse effluent is discharged to the CIL tails pump hopper and the batch of acid-washed carbon is then transferred into the elution column.

The acid wash sequence is manually controlled by the operator and all valves are opened or closed manually. The acid wash column is equipped with diaphragm-protected pressure gauge to indicate blockage of the acid wash strainer.


To transfer acid washed carbon, residual acid solution in the acid wash column is drained back to the acid wash tank. The transfer water pump pressurises the acid wash column and supplies transport water to the outlet bend at the base of the acid wash column. A slurry of carbon in water is delivered to the elution column. Excess water is drained from the elution strainer back to the transfer water tank.

Periodically (typically every 3 to 4 acid washes) the dilute acid in the acid wash tank becomes too contaminated for further use. Sufficient sodium hydroxide is pumped to the acid wash tank to neutralise the spent acid. The acid wash pump is used to pump the discarded liquor to the CIL tails pump hopper. Fresh raw water is used to refill the acid wash tank and sufficient fresh concentrated hydrochloric acid is added to make up the required hydrochloric acid strength (~3%). Water addition to the acid wash tank to make-up fresh dilute acid solution is controlled by a manual valve.


The acid wash system requires operator intervention at various times during the sequence as all valves are opened or closed manually.

4.8.2 ElutionRefer to P&ID 1475-P074 Elution.

The elution section uses the pressure Zadra method. The elution liquor, a dilute sodium hydroxide-cyanide solution is pumped from the elution tank via the recovery heat exchanger and elution heater into the elution column under elevated temperature. The heater burners heat the eluate solution directly. Hot eluant solution exiting the elution column is cooled in the recovery heat exchanger by contacting with fresh eluate solution being pumped into the heater.


To start an elution, the sodium hydroxide and cyanide concentrations in a sample of the eluate solution in the elution tank are checked and if required, corrected by adding fresh reagents. The eluate solution is pumped, using the elution pump, through the heat exchanger, heater, elution column and elution strainers (one duty/one standby) to the CIL electrowinning cell. Barren electrolyte is returned from the cell outlet to the elution tank.

On completion of an elution, carbon is transferred to the eluted carbon screen above the kiln feed hopper. The transfer water pump pressurises the elution column and supplies transport water to the outlet bend at the base of the column. A slurry of carbon in water is delivered to the screen. Carbon drops into the hopper and excess water is drained back to the transfer water tank.


Eluate solution can be reused for a number of elutions until the level of contamination becomes unacceptable. The spent eluate is pumped to CIL via the spent eluate tank by the elution pump after opening the spent eluate discharge valve (XV8730). The benefit of any available sodium hydroxide and cyanide in the spent eluate is used and the carbon in the CIL can recover the residual gold values. The elution heater is interlocked to the valve open position so the heater cannot be operated without eluate flow nor eluate disposed of by accident during an elution.

To make a new batch of eluate solution, the elution tank is filled with raw water and sufficient cyanide and sodium hydroxide solutions added. Water addition to the elution tank to make-up fresh eluant solution is controlled by a manual valve.

The elution system requires operator intervention at various times during the sequence as all valves are opened or closed manually.


The elution tank is equipped with a low level switch interlocked to trip the elution pump at low level. The elution pump is a helical rotor type pump and cannot be run dry.

The elution column outlet is equipped with a pressure and temperature gauges. Pressure and temperature gauges are supplied at the inlets and outlets of the heat exchanger. A temperature gauge is installed at the elution tank.

The outlet of the heater is equipped with a temperature gauge as well as a temperature measurement device. This is used to control the elution heating system. The heater system is automated and has a local control panel. The elution column pressure is controlled by the operator who manually adjusts the position of a throttling valve on the eluate outlet of the recovery heat exchanger.


4.8.3 RegenerationRefer to P&ID 1475-P075 Regeneration.

When the elution sequence is complete, the operator can divert the transfer of carbon direct to CIL via the regen carbon screen or to regeneration via the eluted carbon screen.

Screened eluted carbon is discharged into the kiln feed hopper. Carbon is fed to the regeneration kiln situated on top of the CIL tanks by the kiln screw feeder.

Regenerated carbon from the kiln is quenched in the carbon quench pan and passes over the regen carbon screen at the CIL. The screen removes excess water and carbon fines. Carbon is discharged into the last CIL tank to replace loaded carbon transferred upstream.


Water and carbon fines passing through the eluted carbon screen gravitate to the transfer water tank. Water and carbon fines passing through the regen carbon screen gravitate to the detox tank.

The regeneration section operates intermittently depending on the availability and activity of eluted carbon and the requirements for regenerated carbon to be added to the CIL.


Regeneration is performed as a manually controlled sequence and all valves are opened or closed manually. Operator intervention or acknowledgement is required at various times during the procedure. Kiln heating is controlled by the vendor’s instrumentation and control system. An emergency drive system is incorporated to protect the heated kiln retort tube from distortion if the main power supply is interrupted. Changeovers from mains supply to emergency supply and vice versa are automatic and instantaneous. The battery supply will drive the tube for a minimum period to allow the tube to cool to a safe temperature.

4.9 ElectrowinningRefer to P&ID 1475-P076 Electrowinning.


Gold in the ILR electrolyte and eluate is plated separately onto cathodes in the dedicated ILR and CIL electrowinning cells.

Periodically, the operator uses the electrowinning hoist to remove the anodes from the cells after isolating the rectifier and feed systems. The anodes are stored in an anode “horse” allowing the operator to raise the cathodes utilising the same hoist. The gold sludge adhering to the cathode mesh is removed by washing with a high-pressure water spray and collected in the body of the electrowinning cell.

Rectifier voltage and current is displayed and adjusted at the rectifiers located adjacent to the outside wall of the goldroom.


The plated precious metals are washed from the stainless steel mesh cathodes using the high-pressure cathode wash pump directly into the cell. The pan filter dewaters the resultant sludge that is collected and this is then dried in the calcine oven prior to mixing with fluxes and placement into the smelting furnace.

To collect cathode sludge, after electrowinning is complete, the rectifier is switched off and electrically isolated, the cells are drained via a decant line, to within 100 mm of the cell bottom to discard the majority of the solution. This decant line is run to the electrowinning spillage pump sump. The electrowinning spillage pump delivers to the elution tank Solution flow from the cell during the decant draining step is controlled by a manual valve to ensure cell exit velocities are low enough to avoid solids entrainment and to match the flow rate to the electrowinning spillage pump capacity.


After draining, the fume hood is removed and the anode pack is carefully lifted from the cell with the cathode hoist, hosing off any residual sludge that may have adhered to the anode plates into the cell. The anode pack is then removed from the cell and placed in the anode holding frame, freeing the overhead monorail and electric hoist for lifting and removal of the cathode pack.

The vacuum system is then started and the receiver evacuated. The remaining cell solution is drained to the vacuum filter and the operator matches the filter feed and vacuum receiver inlet flows, to prevent filter overflows, by adjusting feed and discharge valves. Once the remaining cell solution has been filtered, the vacuum system is regulated to accept the lower flow of solids and wash water being drained from the cell during the cell cleaning step.


Using the cathode hoist, the cathode pack is carefully raised from the cell and each cathode is progressively hosed off, into the cell, using the cathode wash pump. This stream of sludge and wash water is filtered concurrently with the cell cleaning process. The vacuum receiver is sized to contain the residual cell solution after decanting plus a nominal volume of wash water, such that it should not be necessary to drain the receiver during the cell clean out process. This volume is later drained from the receiver to the electrowinning spillage pump sump. If this nominal volume of wash water is exceeded during the cell clean out process, it is necessary to shut down the vacuum pump and drain the receiver. A high-level switch in the receiver will trip the vacuum pump to protect against overfilling of the receiver and consequently filling the vacuum pump with filtrate.


After filtering, the solids are recovered from the vacuum filter by tilting the filter pan and shovelling to metal drying trays. The trays are manually lifted into a drying oven to remove any remaining moisture.

Each electrowinning cell is fitted with a fume hood. This is arranged over the cell and connected to a plenum chamber that in turn connects to the goldroom scrubber to scrub the fume and vapours before discharge to atmosphere via the stack. Control of the airflows through this venting system is by means of manually adjusted slide plate dampers. The anode and cathode packs of the cell are fitted with a dedicated laminated busbar to conduct current. Air drawn into the cell enters via spaces between the laminations of the cell’s cathode and anode busbars, thus providing cooling.


The tails from the ILR electrowinning cell gravitate to the ILR cell tail pump hopper. The ILR cell tail pump (one duty/one standby) delivers the cell tail solution back to the ILR thickener. The level in the hopper is maintained by a float valve connected to the pump delivery.

A high level in the ILR cell tail pump hopper closes an actuated valve in the pregnant solution pipeline from the ILR to prevent flooding in the goldroom.

4.10 Cyanide DetoxificationRefer to P&ID 1475-P077 Cyanide Detoxification Sheet 1 and 1475-P078 Cyanide Detoxification Sheet 2.


The discharge of the last CIL tank, combined with the underflow from the regen carbon screen gravitates into the detox tank where cyanide in solution is reduced to acceptable levels before disposal of the CIL tailings. Cyanide detoxification is based on SO2/air technology. The detox tank provides approximately 90 minutes retention time at design throughputs and is equipped with the detox tank agitator.

A magnetic flowmeter is installed on the CIL tails pump delivery. The volume of CIL tails pumped is measured. The slurry density pumped is measured by the operator from samples using a Marcy scale and entered into the SCADA system. The volumetric flowrate and slurry density is used to calculate the solution flowrate.


The speed of the SMBS dosing pump adding solution to the detox tank is ratio controlled from the CIL tails volumetric flowrate measured by a flowmeter and calculated CNwad level in the tails solution. A fixed adjustment is made to the CIL tails volumetric flowrate as measured by the flowmeter to account for the volume of carbon safety screen sprays and dilution water into the CIL tails pump hopper.

The free cyanide (CNfree) level in the detox tank feed slurry is routinely measured by the operator by titration of slurry filtrate samples. The CNfree level is input via the SCADA along with a ratio for predicting weak acid dissociable cyanide (CNwad) levels based on actual CNwad compared to actual CNfree measurements determined from operating experience.


The speed of the copper sulphate dosing pump adding solution to the detox tank is ratio controlled from the CIL tails volumetric flowrate and manually input slurry density and the copper sulphate addition rate set point in grams Cu2+ per cubic metre of solution.

Duplicate pH probes are installed in the detox tank. A selected probe provides input to the detox pH control loop. The loop output controls a pulsing lime-dosing valve on the lime ringmain to maintain a pH in the tank between 8.5 and 9.5. The signals from the two probes are compared in the event one probe is out of calibration. If a significant difference in signal is detected, an alarm advises the operator of the discrepancy. The most accurate pH probe is determined and control switched to this probe. The inaccurate probe is cleaned, recalibrated or replaced so that the readings from the two probes coincide.


Oxygen is added to the tank through a sparger system. Rotameters measure the gas-flow and flow is adjusted by manual operated needle valves.

The detoxified slurry discharging from the tank passes through the CIL tail screen. Screen oversize reports to the carbon basket. The carbon basket is equipped with wedge wire mesh panels to allow excess slurry to drain away, retaining the carbon. The basket can be removed with a forklift or hoisted with a crane and emptied. The empty basket can then be replaced.

Screen undersize gravitates to the CIL tails pump hopper. Discharge from the hopper is pumped to the CIL tails storage facility by the variable speed CIL tails pump (one duty/one standby). Pump speed is adjusted to maintain a specified level in the pump hopper. Each pump has actuated valves for isolation of suction, discharge and gland water.


Water is reclaimed from the CIL tails storage facility by the CIL tails decant pump (one duty) and returned to the CIL water tank for re-use.

A thermal flow switch is installed on each decant pump delivery. If a no flow situation is detected by the switch, due to the CIL water tank being full and the outlet float valve being closed, or the TSF being dry, the switch stops the decant pump. The switch is linked to a timer and the pump will restart after a 20 minute delay.

5 PERMISSIVES AND INTERLOCKS

5.1 General


Interlocks and permissives are programmed into the control system consistent with the control philosophy.

Permissives need to be satisfied prior to starting equipment to ensure that equipment is not damaged and that operational hazards are prevented. Similarly, interlocks have been programmed into the control system to stop and protect equipment, or equipment around it, under circumstances where associated equipment stops or process conditions dictate it.

The following sections list the permissives and interlocks required to operate the equipment in the respective areas.


5.2 CrushingDrive

Description

Drive

Number

Permissive to Start Running Interlock

Primary crusher feeder

10-FE-001 Primary jaw crusher running

Crusher product conveyor running

LAH1003 not activated


Primary jaw crusher stops

Crusher product conveyor stops

LAH1003 activated

LAH1015 activated

LALL1079 activated


Drive

Description

Drive

Number


Primary jaw crusher

10-CR-001 Primary crusher healthy

Lubrication system selected to ON

Lubrication system running

Primary crusher lubrication system OFF for a set time

Crusher product conveyor

10-CV-001 Secondary screen running

Pull-wire switch not activated XA1006

Belt drift switch not activated ZA1007

Secondary screen stops

Pull-wire switch activated XA1006

Belt drift switch activated ZA1007

Conveyor underspeed switch activated SAL1005


Drive

Description

Drive

Number


Secondary screen

10-SC-001 Secondary crusher feed bin feed conveyor running

Fine ore bin feed conveyor running

Secondary crusher feed bin feed conveyor stops

Fine ore bin feed conveyor stops


Drive

Description

Drive

Number


Secondary crusher feed bin feed conveyor

10-CV-002 LAHH1015 not activated OR ZSC1076 activated (bin bypassed)


Belt drift switch not activated ZS1012

ZSA1076 not activated

LAHH1015 activated


Belt drift switch activated ZS1012

ZSA1076 activated



Drive

Description

Drive

Number


Fine ore bin feed conveyor

10-CV-003 LAHH1023 not activated



HPGR magnet switched on

LAHH1023 activated




HPGR magnet switched off


Drive

Description

Drive

Number


Secondary crusher feeder

10-FE-002 Secondary cone crusher running


Crusher product conveyor stops

Secondary cone crusher stops

LAH1016 activated

Secondary cone crusher

10-CR-002 Crusher product conveyor running

Secondary cone crusher healthy

Lubrication system selected to ON

Lubrication system running

Secondary crusher lubrication system OFF for a set time


Drive

Description

Drive

Number


Crusher spillage pump

10-PU-001 LAHH1051 not activated LAHH1051 activated

Stormwater col-lection pump

10-PU-054 LAH7008 not activated LAH7008 activated


5.3 Fine Ore Bin, HPGR, Grinding and GravityDrive

Description

Drive

Number


Fine ore bin belt feeder

10-FE-003 HPGR feed conveyor running

LAL1023 not activated



HPGR feed conveyor stops

LAL1023 activated





Drive

Description

Drive

Number


HPGR feed conveyor

10-CV-004 HPGR running

LAHH1044 not activated OR ZSC1042 activated



LAL7003 not activated (process water tank)

LAL7008 not activated (raw water tank)

HPGR stops

Mill feed conveyor stops

LAHH1044 activated




LAL7003 activated

LAL7008 activateddocument.doc Page 159

Drive

Description

Drive

Number


Mill feed con-veyor

10-CV-005 Ball mill screen running





Mill pump running

Cyclone pump running

Ball mill screen stops

LAH2067 activated

LAH2098 activated



Conveyor underspeed switch activ-ated SAL1045

Mill pump stops

Cyclone pump stopsdocument.doc Page 160

Drive

Description

Drive

Number


Mill screen over-size conveyor

10-CV-006 LAHH1044 not activated OR ZSC1042 activated

Pull-wire switch not activated ZA1036


ZSA1042 not activated

LAHH1044 activated

Pull-wire switch activated ZA1036



ZSA1042 activated


Drive

Description

Drive

Number


Ball mill screen 20-SC-002 Mill screen oversize conveyor run-ning

Mill pump running

Mill screen oversize conveyor stops

Mill pump stops

HPGR 20-CR-003 Mill feed conveyor running

HPGR healthy

Mill feed conveyor stops

HPGR not healthy


Drive

Description

Drive

Number


Mill pump 20-PU-003 XV2017 or XV2018 or XV2019 open

Process water pump running

FAL2006/08 not activated

XV2017 & XV2018 & XV2019 all closed

Primary jig no.1 feed valve open

XV2017 Primary jig no.1 running Primary jig no.1 stops (valve closes)




Drive

Description

Drive

Number




Cyclone pump 20-PU-004 Flotation feed thickener running

Process water pump running


Primary jig no.1 20-GC-001 Process water pump running



Drive

Description

Drive

Number



Centrifugal con-centrator No 1

20-GC-004A Process water pump running

Ball mill 20-ML-001 Refer Outokumpu design document 7330-DD01 Rev0

Refer Outokumpu design document 7330-DD01 Rev0


5.4 Flotation


Drive

Description

Drive

Number


Flotation feed thickener under-flow pump

30-PU-006 FAL3006/09 not activated

Flotation tail pump

30-PU-007 Flotation tail thickener running



LAH4023 activated

Flotation concen-trate pump

30-PU-008 Concentrate thickener running


Drive

Description

Drive

Number


Flotation tails sampler transfer pump

30-PU-081 Flotation tail thickener running

Flotation concen-trate thickener underflow pump

30-PU-010 Trash screen running

LAHH8319 not activated

LAHH8319 activated

Flotation tail thickener under-flow pump

40-PU-013 FAL4007/09 not activated


Drive

Description

Drive

Number


Sand pump 1 40-PU-072 FAL4031/33 not activated

Sand pump 2 40-PU-072 Sand pump 1 running


Flotation feed sampler

30-SA-001 Flotation feed thickener underflow pump running

XV3014 open

Flotation feed thickener underflow pump stops

XV3014 closed


Drive

Description

Drive

Number


Flotation tails primary sampler

30-SA-006 Flotation feed thickener underflow pump running

XV3014 open

Flotation feed thickener underflow pump stops

XV3014 closed




Drive

Description

Drive

Number


Collector dosing pump

60-PU-038 LAL6001 not activated Flotation feed thickener underflow pump stops for longer than 60 seconds

Frother pump 60-PU-041 LAL6003 not activated Flotation feed thickener underflow pump stops for longer than 60 seconds

Copper sulphate dosing pump A

60-PU-039A LALL6047 not activated


Flotation feed thickener underflow pump stops for longer than 60 seconds


Drive

Description

Drive

Number


Copper sulphate dosing pump B

60-PU-039B LALL6047 not activated


XC6051 selected for flotation & flota-tion feed thickener underflow pump stops for longer than 60 seconds

XC6051 selected for Detox & CIL tails pump stops for longer than 60 seconds

Copper sulphate dosing pump C

60-PU-039C LALL6047 not activated


CIL tails pump stops for longer than 60 seconds


Drive

Description

Drive

Number


Flocculant dosing pump A

60-PU-043A LALL6005 not activated LALL6005 activated

Cyclone pump stops

Flocculant dosing pump B

60-PU-043B LALL6005 not activated LALL6005 activated

XC6052 selected for flotation feed & cyclone pump stops

XC6052 selected for Flotation tails & flotation tail pump stops


Drive

Description

Drive

Number


Flocculant dosing pump c

60-PU-043C LALL6005 not activated LALL6005 activated

Flotation tail pump stops

Flocculant dosing pump d

60-PU-043D LALL6005 not activated LALL6005 activated

Flotation concentrate pump stops

Flocculant dosing pump e

60-PU-043E LALL6005 not activated LALL6005 activated

Flotation concentrate pump stops


Drive

Description

Drive

Number


Cyanide pump 60-PU-047 LAL6014 not activated

LALL6012 not activated

LAL6014 activated

LALL6012 activated

Cyanide tank wa-ter addition valve open

XV6013 LAHH6012 not activated LAHH6012 activated

Sodium hydrox-ide pump A

60-PU-044A LALL6034 not activated LALL6034 activated

Sodium hydrox-ide pump B

60-PU-044B LALL6034 not activated LALL6034 activated


Drive

Description

Drive

Number


SMBS pump 60-PU-067 LAL6021 not activated

LALL6019 not activated

LAL6021 activated

LALL6019 activated

SMBS tank water addition valve open

XV6020 LAH6019 not activated LAH6019 activated


5.6 Gravity and Flotation Concentrate Leaching


Drive

Description

Drive

Number


Trash screen 80-SC-005 Trash screen underflow pump run-ning

Trash screen un-derflow pump

83-PU-079 CIL agitator No 1 running

Flotation concen-trate sampler

83-SA-003 Flotation concentrate thickener underflow pump running

Flotation concentrate thickener underflow pump stops

CIL tails sampler airlift

83-SA-005 Trash screen underflow pump running

Trash screen underflow pump stops


Drive

Description

Drive

Number


Detox tails sampler

90-SA-004 Trash screen underflow pump running

Trash screen underflow pump stops

Final CIL tail sampler

90-SA-008 CIL tails pump running CIL tails pump stops

Loaded carbon screen

83-SC-006 LAH8702 not activated LAH8702 activated




Drive

Description

Drive

Number


Acid wash pump 87-PU-025 LAL8701 not activated LAL8701 activated

Elution heater 1 87-HE-001 Refer to vendor manual

XV8730 closed


Elution pump running

Refer to vendor manual

XV8730 opens

LAL8705 activated

Elution pump stops

Elution pump 87-PU-024 LALL8705 not activated LALL8705 activated


Drive

Description

Drive

Number


Regeneration kiln 87-KN-001 Refer to vendor manual Refer to vendor manual

5.8 ElectrowinningDrive

Description

Drive

Number


Pan filter vacuum pump

85-VP-001 LAH8504 not activated


LAH8504 activated



5.9 Cyanide Detoxification


Drive

Description

Drive

Number


CIL tails pump 90-PU-022 FAL9011/13 not activated


Nil


5.10 Goldroom -SmeltingDrive

Description

Drive

Number


Smelting furnace 50-FU-001 PDAH5005 not activated PDAH5005 activated


6 PROCESS CONTROL LOOPS

6.1 Crushing

6.1.1 Primary Crusher Feeder

Objective:Feed rate to the primary crusher is controlled to maintain required throughput.

Modes of Operation:

a) Remote Manualdocument.doc Page 187

ControlMode

Controller

Tag

Controller

Mode

Controller Input Controller Output

Remote SC1002 Manual Nil To primary crusher feeder speed ratio controller SC1002


6.1.2 Secondary Crusher Feeder

Objective:Feed rate to the secondary crushing circuit is controlled to maintain required throughput.

Modes of Operation:

a) Remote Auto - the operator selects a bin level set-point and the level controller adjusts the speed of the feeder.

b) Remote Manual - the operator selects the speed of the feeder through the bin level controller.


ControlMode

Controller

Tag

Controller

Mode


Remote LIC1015 Auto Set-point for LIC1015

Process variable for LIC1015

To secondary crusher feeder VVVF drive SC1089

LIC1015 Manual Nil To secondary crusher feeder VVVF drive SC1089


6.2 Fine Ore Bin, HPGR, Grinding and Gravity

6.2.1 Fine Ore Bin Belt Feeder

Objective:Feed rate to the HPGR is controlled to maintain required throughput.

Modes of Operation:

a) Remote Auto - the operator selects the desired HPGR feed rate set-point through the HPGR feed rate controller, which regulates the speed of the feeder so that the weightometer reading will match the set-point.


b) Remote Auto (Override) - the output of the HPGR feed rate controller is driven to a minimum while the HPGR feed bin high level alarm condition is active.

c) Remote Manual - the operator selects the speed of the feeder through the HPGR feed rate controller.

d) Remote Manual (Override) - the output of the HPGR feed rate controller is driven to a minimum while the HPGR feed bin high level alarm condition is active.


ControlMode

Controller

Tag

ControllerMode


Remote WIC1033 Auto Set-point for WIC1033

Process variable for WIC1033

To fine ore bin belt feeder VVVF drive SC1033

LIC1044 Auto(Override)

LAH1044 Fine ore bin belt feeder VVVF drive SC1033 to minimum

WIC1033 Manual Nil To fine ore bin belt feeder VVVF drive SC1033


ControlMode

Controller

Tag

ControllerMode


LIC1044 Manual (Override)

LAH1044 To fine ore bin belt feeder VVVF drive SC1033 to minimum


6.2.2 HPGR Roll Speed

Objective:Feed rate to the HPGR rolls is controlled to maintain required throughput and choke feed condition.

Modes of Operation:

a) Remote Auto - the operator selects a HPGR feed bin level set-point and the level controller adjusts the speed of the HPGR rolls.

b) Remote Manual - the operator selects the speed of the HPGR rolls through the HPGR feed bin level controller.


ControlMode

Controller

Tag

Controller

Mode


Remote WIC1033 Auto Set-point for LIC1044


To HPGR VVVF drive SC1090A/B

WIC1033 Manual Nil To HPGR VVVF drive SC1090A/B


6.2.3 Mill Pump Hopper Level

Objective:Level of the mill pump hopper is controlled to maintain required throughput.

Modes of Operation:

a) Remote Auto - the operator selects a mill pump hopper level set-point and the level controller adjusts the speed of the mill pump.

b) Remote Auto (Override) - the output of the mill pump hopper level controller is driven to a minimum while the cyclone underflow launder high-level alarm condition is active.


c) Remote Manual - the operator selects the speed of the mill pump through the mill pump hopper level controller.

d) Remote Manual (Override) - the output of the mill pump hopper level controller is driven to a minimum while the cyclone underflow launder high-level alarm condition is active.


ControlMode

Controller

Tag

Controller

Mode




To mill pump VVVF drive SC2089A/B

LIC2009 Auto (Override)

LAH2067 Mill pump VVVF drive SC2089A/B to minimum

LIC2009 Manual Nil To mill pump VVVF drive SC2089A/B


ControlMode

Controller

Tag

Controller

Mode



LAH2067 Mill pump VVVF drive SC2089A/B to minimum


6.2.4 Mill Pump Hopper Water Addition

Objective:Mill pump hopper water addition is controlled to maintain required mill pump delivery slurry density.

Modes of Operation:

a) Remote Auto - the operator selects a mill pump delivery density set-point and the density controller adjusts the position of the flow control valve.

b) Remote Manual - the operator selects the position of the flow control valve through the mill pump delivery density controller.


ControlMode

Controller

Tag

Controller

Mode


Remote DIC2016 Auto Set-point for DIC2016

Process variable for DIC2016

To FCV-2003 positioner

DIC2016 Manual Nil To FCV-2003 positioner


6.2.5 Mill Feed End Water Addition

Objective:Flowrate of mill feed end water addition is controlled to maintain mill operating slurry density.

Modes of Operation:

a) Remote Auto - the operator selects a mill feed end water addition flow set-point and the flow controller adjusts the position of the flow control valve.


b) Remote Manual - the operator selects the position of the flow control valve through the mill feed end water addition flow controller.

ControlMode

Controller

Tag

Controller

Mode


Remote FIC2097 Auto Set-point for FIC2097

Process variable for FIC2097


FIC2097 Manual Nil To FCV-2092 positioner


6.2.6 Mill Screen Gold Trap Feed Water

Objective:Density of the mill screen gold trap feed is controlled to maintain flow through the trap.

Modes of Operation:

a) Remote Auto - the operator selects a mill screen gold trap feed water addition flow set-point and the flow controller adjusts the position of the flow control valve.

b) Remote Manual - the operator selects the position of the flow control valve through the mill screen gold trap feed water addition flow controller.


ControlMode

Controller

Tag

Controller

Mode


Remote FIC2091 Auto Set-point for FIC2091

Process variable for FIC2091




6.2.7 Cyclone Pump Hopper Level

Objective:Level of the cyclone pump hopper is controlled to maintain required throughput.

Modes of Operation:

a) Remote Auto - the operator selects a cyclone pump hopper level set-point and the level controller adjusts the speed of the cyclone pump.


b) Remote Auto (Override) - the output of the cyclone pump hopper level controller is driven to a minimum while the cyclone underflow launder high-level alarm condition is active.

c) Remote Manual - the operator selects the speed of the cyclone pump through the cyclone pump hopper level controller.

d) Remote Manual (Override) - the output of the cyclone pump hopper level controller is driven to a minimum while the cyclone underflow launder high-level alarm condition is active.


ControlMode

Controller

Tag

Controller

Mode




To cyclone pump VVVF drive SC2090A/B


LAH2067 Cyclone pump VVVF drive SC2090A/B to minimum

LIC2048 Manual Nil To cyclone pump VVVF drive SC2090A/B


ControlMode

Controller

Tag

Controller

Mode



LAH2067 Cyclone pump VVVF drive SC2090A/B to minimum


6.2.8 Cyclone Pump Hopper Water Addition

Objective:Cyclone pump hopper water addition is allowed if the hopper level reaches a low level.

a) Remote Auto - the water dilution valve is opened fully while the cyclone pump hopper low level alarm condition is active.

b) Remote Manual - the operator selects the position of the water dilution valve through the cyclone pump hopper water addition valve controller.


ControlMode

Controller

Tag

Controller

Mode


Remote XV2072 Auto LAL2048 XV2072 positioner to open

XV2072 Manual Nil XV2072 positioner to open


6.2.9 Gravity Concentrate Surge Tank Level

Objective:Level of the gravity concentrate surge tank is controlled to prevent overfilling with concentrate by successive concentrate flushing from the spinners and centrifugal concentrator.

Modes of Operation:

a) Remote Auto - the supervisor selects a high-level alarm set-point. At high-level, the PLC opens the actuated valve feeding slurry to the concentrate tank and inhibits any unit from flushing.


ControlMode

Controller

Tag

Controller

Mode


Remote LIC2061 Auto LAH Set-point for LI2061

LAHH Set-point for LI2061

Process variable for LI2061

XV2066 positioner to open at LAH

LAHH inhibit flush signal (order of priority):

Centrifugal concentrator

Spinner No 1

Spinner No 2

Spinner No 3

Spinner No 4


6.2.10 Mill Screen Gold Trap Purge

Objective:The mill screen gold trap is purged on a timer set basis or manually by the operator as required.

Modes of Operation:

a) Remote Auto - the operator selects a running time and the controller purges the trap on expiry and restarts the timer.

b) Remote Manual - the operator selects a purge cycle through the controller.


ControlMode

Controller

Tag

Controller

Mode


Remote KC2002 Auto running time set-point for KC2002

open time set-point for XV2001

open time set-point for XV2002

Timer expires

XV2001 open for set time

XV2001 to close


XV2002 to close


ControlMode

Controller

Tag

Controller

Mode


KC2002 Manual open time set-point for XV2001

open time set-point for XV 2002


XV2001 to close


XV2002 to close


6.3 Flotation

6.3.1 Flotation Feed Thickener Underflow Slurry Density

Objective:Density of flotation feed slurry is controlled to maintain required throughput and optimum flotation performance.

Modes of Operation:


a) Remote Auto - the operator selects a flotation feed thickener underflow slurry density set-point and the density controller adjusts the speed of the flotation feed thickener underflow pump.

b) Remote Manual - the operator selects the speed of the flotation feed thickener underflow pump through the flotation feed thickener underflow slurry density controller.

ControlMode

Controller

Tag

Controller

Mode




To flotation feed thickener underflow pump VVVF drive SC3074A/B


ControlMode

Controller

Tag

Controller

Mode


DIC3012 Manual Nil To flotation feed thickener underflow pump VVVF drive SC3074A/B


6.3.2 Conditioning Tank Slurry Density

Objective:Density of flotation feed slurry is by a cascade loop to maintain required throughput and optimum flotation performance. The dilution water addition flow meter set-point is calculated in the PLC. The PLC measures the thickener underflow slurry density and slurry volumetric flow. The solids dry tonnage flowrate and solution flowrate in the thickener underflow is calculated. The desired conditioning tank slurry density set-point is entered. The PLC calculates the thickener underflow slurry solution flowrate and the required conditioning tank overflow slurry solution flowrate based on the flotation feed density set-point and calculated solids dry tonnage flowrate. The difference in volumetric flow cascades to the flow control loop as the flow set-point.


Modes of Operation:

a) Remote Auto 1 - the operator selects a conditioning tank slurry density (entered as solids % w/w) and the PLC calculates a flow set-point for the conditioning tank dilution water flow controller. The flow controller adjusts the position of the flow control valve to match the set-point.

b) Remote Auto 2 - the operator selects a conditioning tank dilution water flow set-point and the flow rate controller adjusts the position of the flow control valve.

c) Remote Manual - the operator selects the position of the flow control valve through the conditioning tank dilution water flow controller.



ControlMode

Controller

Tag

Controller

Mode


Remote FIC3001 Auto 1 Set-point for FIC3001 from FY3012

FY3012 inputs:

Process variable from WIC3012

Process variable from DIC3012

Set-point from HX3012

Solids SG (t/m³) (Supervisor level access only)



ControlMode

Controller

Tag

Controller

Mode


FIC3001 Auto 2 Set-point for FIC3001 To FCV-3011 positioner



6.3.3 Flotation Tails Pump Hopper Level

Objective:Level of the flotation tails pump hopper is controlled to maintain required throughput.

Modes of Operation:

a) Remote Auto - the operator selects a flotation tails pump hopper pump hopper level set-point and the level controller adjusts the speed of the flotation tails pump.

b) Remote Manual - the operator selects the speed of the flotation tails pump through the flotation tails hopper level controller.


ControlMode

Controller

Tag

Controller

Mode




To flotation tails pump VVVF drive SC3075A/B

LIC3020 Manual Nil To flotation tails pump VVVF drive SC3075A/B


6.3.4 Flotation Concentrate Thickener Underflow Slurry Density

Objective:Density of flotation concentrate thickener underflow slurry is controlled to maintain required throughput, optimum thickener performance and optimum CIL feed slurry density.

Modes of Operation:

a) Remote Auto - the operator selects a flotation concentrate thickener underflow slurry density set-point and the density controller adjusts the speed of the flotation concentrate thickener underflow pump.


b) Remote Manual - the operator selects the speed of the flotation concentrate thickener underflow pump through the flotation concentrate thickener underflow slurry density controller.

ControlMode

Controller

Tag

Controller

Mode




To flotation concentrate thickener underflow pump VVVF drive SC3076A/B


ControlMode

Controller

Tag

Controller

Mode


DIC3035 Manual Nil To flotation concentrate thickener underflow pump VVVF drive SC3076A/B


6.3.5 Flotation Tailings Thickener Underflow Slurry Density

Objective:Density of flotation tailings thickener underflow slurry is controlled to maintain required throughput, optimum thickener performance and correct TSF feed slurry density.

Modes of Operation:

a) Remote Auto - the operator selects a flotation tailings thickener underflow slurry density set-point and the density controller adjusts the speed of the flotation tailings thickener underflow pump.


b) Remote Manual - the operator selects the speed of the flotation tailings thickener underflow pump through the flotation tailings thickener underflow slurry density controller.

ControlMode

Controller

Tag

Controller

Mode




To flotation tailings thickener underflow pump VVVF drive SC4055A/B

DIC4010 Manual Nil To flotation tailings thickener underflow pump VVVF drive SC4055A/B



6.3.6 Sand Pump Delivery Slurry Density

Objective:Density of the sand pump delivery slurry is controlled to maintain required throughput, optimum and correct TSF feed slurry density.

Modes of Operation:

a) Remote Auto - the operator selects a sand pump delivery slurry density set-point and the density controller adjusts the position of the sand pump hopper dilution water flow control valve.


b) Remote Manual - the operator selects the position of the sand pump hopper dilution water flow control valve through the sand pump delivery density controller.

ControlMode

Controller

Tag

Controller

Mode


Remote DIC4038 Auto Select DIC4038 A or B

Set-point for DIC4038



DIC4038 Manual Nil To FCV-4039 positioner


6.3.7 Sand Pump Hopper Level

Objective:Level of the sand pump hopper is controlled to maintain required throughput. The variable speed sand pump controller has a minimum speed setting to prevent the pipeline sanding up under normal conditions.

Modes of Operation:

a) Remote Auto - the operator selects a sand pump hopper level set-point and the level controller adjusts the speed of sand pump 2.


b) Remote Auto (Override) - the sand pump hopper water dilution valve is opened fully while the alarm condition is active.

c) Remote Manual - the operator selects the speed of sand pump 2 through the sand pump hopper level controller.

d) Remote Manual (Override) - the sand pump hopper water dilution valve is opened fully while the alarm condition is active.


ControlMode

Controller

Tag

Controller

Mode




To sand pump 2 VVVF drive SC4056A/B


LAL4023 activated FCV-4039 positioner to open

LIC4023 Manual Nil To sand pump 2 VVVF drive SC4056A/B


LAL4023 activated FCV-4039 positioner to open


6.3.8 Flotation Tails Decant Pump

Objective:The flotation tails decant pump is stopped if the process water tank is full and the float valve closes.

Modes of Operation:

a) Local Auto


ControlMode

Controller

Tag

Controller

Mode


Local FAL4017 Auto FAL4017 activated Flotation tails decant pump stop

Initiate restart timer


6.3.9 Seepage Pump

Objective:Seepage pump is started if sump is full and stopped if sump is empty.

Modes of Operation:

a) Local Auto


ControlMode

Controller

Tag

Controller

Mode


Local LSL4018 Auto LSL018 activated Seepage decant pump start


ControlMode

Controller

Tag

Controller

Mode


Local LSL4019 Auto LSL019 activated Seepage decant pump stop


6.3.10 Tailings Drainage Containment Pump

Objective:Tailings drainage containment pump is started if the sump is full and stopped if the sump is empty.

Modes of Operation:

a) Local Auto


ControlMode

Controller

Tag

Controller

Mode


Local LSL4046 Auto LSL046 activated Tailings drainage containment pump start

Local LSL4047 Auto LSL047 activated Tailings drainage containment pump decant pump stop



6.4.1 Collector Dosing Pump Speed

Objective:Collector addition is ratio controlled to the flotation feed rate measured by the flotation feed thickener underflow mass flow system. Both pumps may be operated at the same time if required.

Modes of Operation:


a) Remote Auto - the operator selects a ratio of pump speed to the flotation feed thickener integrated dry tonnage flow rate and the collector addition rate controller adjusts the speed of the collector dosing pump.

b) Remote Manual - the operator selects the speed of the collector dosing pump through the collector addition rate controller.


ControlMode

Controller

Tag

Controller

Mode


Remote SIC6002 Auto Collector solution concentration (Supervisor level access only)

Pump flowrate at 100% output (Supervisor level access only)

Operator entered ratio (g/t)


Collector dosing pump VVVF drive SC6002A/B

SIC6002 Manual Nil Collector dosing pump VVVF drive SC6002A/B


6.4.2 Frother Dosing Pump Speed

Objective:Frother addition is ratio controlled to the flotation feed rate measured by the flotation feed thickener underflow mass flow system. Both pumps may be operated at the same time if required.

Modes of Operation:

a) Remote Auto - the operator selects a ratio of pump speed to the flotation feed thickener integrated dry tonnage flow rate and the frother addition rate controller adjusts the speed of the frother dosing pump.


b) Remote Manual - the operator selects the speed of the frother dosing pump through the frother addition rate controller.

ControlMode

Controller

Tag

Controller

Mode


Remote SIC6004 Auto Frother solution concentration (Supervisor level access only)




To frother dosing pump VVVF drive SC6004A/B


ControlMode

Controller

Tag

Controller

Mode


SIC6004 Manual Nil To frother dosing pump VVVF drive SC6004A/B


6.4.3 Copper Sulphate (Flotation) Dosing Pump Speed

Objective:Flotation copper sulphate addition is ratio controlled to the flotation feed rate measured by the flotation feed thickener underflow mass flow system. As copper sulphate dosing pump B is a common standby, a selection (XC6051) must be made to ensure the correct controller output is fed to the pump.

Modes of Operation:

a) Remote Auto - the operator selects a ratio of pump speed to the flotation feed thickener integrated dry tonnage flow rate and the flotation copper sulphate addition rate controller adjusts the speed of the copper sulphate dosing pump.


b) Remote Manual - the operator selects the speed of the flotation copper sulphate dosing pump through the copper sulphate addition rate controller.

ControlMode

Controller

Tag

Controller

Mode


Remote SIC6045 Auto CuSO4 mix strength (Supervisor level access only)




To copper sulphate dosing pump VVVF drive SC6024/25


ControlMode

Controller

Tag

Controller

Mode


SIC6045 Manual Nil To copper sulphate dosing pump VVVF drive SC6024/25


6.4.4 Copper Sulphate (Detox) Dosing Pump Speed

Objective:Detox copper sulphate addition is ratio controlled to the detoxified CIL tails flow rate. As copper sulphate dosing pump B is a common standby, a selection (XC6051) must be made to ensure the correct controller output is fed to the pump.

A fixed adjustment is made to the CIL tails volumetric flowrate as measured by the flowmeter to account for the volume of carbon safety screen sprays and dilution water into the CIL tails pump hopper.


The speed of the copper sulphate dosing pump adding solution to the detox tank is ratio controlled from the adjusted CIL tails volumetric flowrate and a manually input CIL tails slurry density and the copper addition rate set point in grams Cu2+ per cubic metre of solution.

Modes of Operation:

a) Remote Auto - the operator selects the copper sulphate mix concentration, copper addition rate set point and estimated average CIL tails slurry density. The ratio is applied to the adjusted CIL tails volumetric flow rate and the detox copper sulphate addition rate controller adjusts the speed of the detox copper sulphate dosing pump.


b) Remote Manual - the operator selects the speed of the detox copper sulphate dosing pump through the detox copper sulphate addition rate controller.


ControlMode

Controller

Tag

Controller

Mode


Remote SIC6040 Auto Operator entered of Cu2+ addition per m³ (Supervisor level access only)

CuSO4 mix strength input (Supervisor level access only)

CIL tails slurry density (Supervisor level access only)

FIC9018 adjustment for dilution (Supervisor level access only)

Pump flowrate at 100% output

To copper sulphate dosing pump VVVF drive SC6026/25


ControlMode

Controller

Tag

Controller

Mode


SIC6040 Manual Nil To copper sulphate dosing pump VVVF drive SC6026/25


6.4.5 Flotation Feed Thickener Flocculant Dosing Pump Speed

Objective:Flotation feed thickener flocculant addition is controlled based on the flotation feed thickener bed level. As flocculant dosing pump B is a common standby, a selection (XC6052) must be made to ensure the correct controller output is fed to the pump.

Modes of Operation:

a) Remote Auto - the operator selects a set point for the flotation feed thickener bed level and the flotation feed thickener bed level controller adjusts the speed of the flocculant dosing pump.


b) Remote Manual - the operator selects the speed of the flotation feed thickener flocculant dosing pump through the flotation feed thickener bed level controller.

ControlMode

ControllerTag

Controller

Mode




To flocculant dosing pump VVVF drive SC6031A/B

LIC3044 Manual Nil To flocculant dosing pump VVVF drive SC6031A/B


6.4.6 Flotation Tail Thickener Flocculant Dosing Pump Speed

Objective:Flotation tail thickener flocculant addition is manually controlled based on the flotation tail thickener bed level. As flocculant dosing pump B is a common standby, a selection (XC6052) must be made to ensure the correct controller output is fed to the pump.

Modes of Operation:

a) Remote Auto - the operator selects a set point for the flotation tail thickener bed level and the flotation tail thickener bed level controller adjusts the speed of the flocculant dosing pump.


b) Remote Manual - the operator selects the speed of the flocculant dosing pump through the flotation tail thickener bed level controller.

ControlMode

ControllerTag

Controller

Mode




To flocculant dosing pump VVVF drive SC6031E/B

LIC4013 Manual Nil To flocculant dosing pump VVVF drive SC6031E/B


6.4.7 Concentrate Thickener Flocculant Dosing Pump Speed

Objective:Concentrate thickener flocculant addition is controlled based on the concentrate thickener bed level.

Modes of Operation:

a) Remote Auto - the operator selects a set point for the concentrate thickener bed level and the concentrate thickener bed level controller adjusts the speed of the flocculant dosing pump.


b) Remote Manual - the operator selects the speed of the flocculant dosing pump through the concentrate thickener bed level controller.

ControlMode

ControllerTag

Controller

Mode




To flocculant dosing pump VVVF drive SC6031C/D

LIC3039 Manual Nil To flocculant dosing pump VVVF drive SC6031C/D


6.4.8 SMBS Dosing Pump Speed

Objective:Detox SMBS is ratio controlled to the CIL tails flow rate and CNfree level in the CIL tails.

Modes of Operation:

a) Remote Auto - the operator selects a ratio based on the SMBS mix concentration, normal CNfree level in the CIL tails and the normally experienced ratio of CNwad to CNfree

in the CIL tails. The ratio is applied to the adjusted CIL tails volumetric flow rate and the SMBS addition rate controller adjusts the speed of the SMBS dosing pump.


b) Remote Manual - the operator selects the speed of the SMBS dosing pump through the SMBS addition rate controller.


ControlMode

Controller

Tag

Controller

Mode


Remote SIC9018 Auto Operator entered ratio of SMBS addition to CNwad level

SMBS mix strength input (Supervisor level access only)

CNfree level input (Supervisor level access only)

CNwad to CNfree ratio input (Supervisor level access only)

FIC9018 adjustment for dilution (Supervisor level access only)

To SMBS dosing pump VVVF drive SC6039A/B


ControlMode

Controller

Tag

Controller

Mode


SIC9018 Manual Nil To SMBS dosing pump VVVF drive SC6039A/B


6.4.9 Lime Make-Up

Objective:Lime and water addition to the lime tank controlled to maintain the lime slurry level in the tank. The relative feedrate of lime and make up water are set to produce the required lime slurry density.

Modes of Operation:

a) Remote Auto


ControlMode

Controller

Tag

Controller

Mode


Remote LI6017 Auto LAL6017 active Lime feeder drive on

Lime silo vibrated fluidiser air open (XV6053)

XV6018 open


ControlMode

Controller

Tag

Controller

Mode


LAH6017 active Lime feeder drive off

Lime silo vibrated fluidiser air closed (XV6053)

XV6018 close


6.4.10 Potable Water Jockey pump

Objective:Potable water jockey pump is stopped if the potable water tank is full and the float valve closes.

Modes of Operation:

a) Local Auto


ControlMode

Controller

Tag

Controller

Mode


Local FAL4017 Auto FAL7001 activated Potable water jockey pump stop

Initiate restart timer


6.5 Gravity and Flotation Concentrate Leaching

6.5.1 CIL Lime Addition

Objective:Lime slurry addition is controlled by the pH measured in CIL tank 1 to maintain the required pH in the CIL slurry.

Modes of Operation:


a) Remote Auto - the operator selects a CIL tank 1 pH set-point and the CIL lime addition controller adjusts the open position time (seconds) of the pulsing CIL lime addition valve. The closed position time (seconds) of the pulsing lime addition valve is closed.

b) Remote Manual - the operator selects the open position time (seconds) of the pulsing CIL lime addition valve through the CIL tank 1 pH controller.


ControlMode

Controller

Tag

Controller

Mode


Remote AIC8301 Auto Selection (XC8301) of AIC8301A or B

Set-point for AIC8301A/B

Process variable from AIC8301A/B

To KC8301 to XV8301 pulse rate


ControlMode

Controller

Tag

Controller

Mode


AIC8301 Manual Nil KC8301 To XV8301 pulse rate


6.5.2 CIL Cyanide Addition

Objective:Cyanide addition to CIL tank 1 is controlled by a cascade loop. The cyanide addition flow meter set-point is calculated in the PLC. The PLC calculates the set-point based on the concentrate thickener underflow mass flow derived from the measured slurry density and volumetric flow. The cyanide solution concentration and required cyanide dosage (expressed in g/t) is entered and the PLC calculates the desired cyanide solution flowrate that cascades to the flow control loop as the flow set-point.

Modes of Operation:


a) Remote Auto 1 - the operator selects a ratio (entered as m³/h per t/h) of cyanide solution to flotation concentrate thickener underflow tonnage flow rate. The PLC calculates a flow set-point for the CIL cyanide addition flow rate controller. The flow controller adjusts the position of the flow control valve to match the set-point.

b) Remote Auto 2 - the operator selects a flow set-point and the CIL cyanide addition flow rate controller adjusts the position of the CIL cyanide flow control valve.

c) Remote Manual - the operator selects the position of the CIL cyanide flow control valve through the CIL cyanide addition flow rate controller.


ControlMode

Controller

Tag

Controller

Mode


Remote FIC8303 Auto 1 Cyanide solution concentration (Supervisor level access only)


Set-point for FIC8303 from WIC3035


FIC8303 Auto 1 Set-point for FIC8303 To FCV-8303 positioner




6.6.1 Elution Temperature

Objective:Temperature of the elution column feed solution is controlled by a temperature element on the heater outlet linked to the heater burner control.

Modes of Operation:

a) Remote Auto - the operator selects an elution temperature set-point and the elution temperature controller adjusts the heater burner output.


b) Remote Manual - the operator selects heater burner output through the elution temperature controller.

ControlMode

Controller

Tag

Controller

Mode


Remote TIC8708 Auto Set-point for TIC8708

Process variable for TIC8708

To elution heater burner controller (vendor supply)

TIC8708 Manual Nil To elution heater burner controller

(vendor supply)


6.7 Electrowinning

6.7.1 ILR Cell Tail Pump Hopper Level

Objective:To prevent spillage of high value cyanide bearing solution in the goldroom, a high-level alarm in the ILR cell tail pump hopper forces an isolation valve on the ILR electrowinning cell feed pipeline to close and recirculates pregnant solution back into the ILR pump hopper.

Modes of Operation:

a) Remote Autodocument.doc Page 284

ControlMode

Controller

Tag

Controller

Mode


Remote LAH8503 Auto LAH8503 activated XV6053 closed


6.8 Cyanide Detoxification

6.8.1 CIL Tails Pump Hopper Level

Objective:Level of the CIL tails pump hopper is controlled to maintain required throughput.

Modes of Operation:

a) Remote Auto - the operator selects a CIL tails pump hopper level set-point and the level controller adjusts the speed of the CIL tails pump.


b) Remote Manual - the operator selects the speed of the CIL tails pump through the CIL tails pump hopper level controller.

ControlMode

Controller

Tag

Controller

Mode




To CIL tails pump VVVF drive SC9022A/B

LIC9007 Manual Nil To CIL tails pump VVVF drive SC9022A/B


6.8.2 Detox Lime Addition

Objective:Lime slurry addition is controlled by the pH measured in the detox tank to maintain the required pH in the detox tank slurry.

Modes of Operation:

a) Remote Auto - the operator selects a detox tank pH set-point and the detox lime addition controller adjusts the open position time (seconds) of the pulsing detox lime addition valve. The closed position time (seconds) of the pulsing lime addition valve is closed.


b) Remote Manual - the operator selects the open position time (seconds) of the pulsing detox lime addition valve through the detox tank pH controller.

ControlMode

Controller

Tag

Controller

Mode


Remote AIC9001 Auto Selection (XC9001) of AIC9001A or B

Set-point for AIC9001A/B

Process variable from AIC9001A/B

To KC9001 to XV9001 pulse rate

AIC9001 Manual Nil To KC9001 to XV9001 pulse rate


7 SEQUENCES AND PROCEDURESSelected automated sequences and manually controlled procedures for start-up and shutdown of the plant are listed below. Note that for an automated sequence or manually controlled procedure to progress permissives and interlocks as detailed above must be satisfied.

Sequences and procedures assume normally continuously running equipment e.g. thickeners, the conditioning tank, Detox and CIL tank agitators are left operating.

Start or stop of a pump with actuated suction and delivery valves automatically opens or closes the valves after the pump running indication is received by the PLC.


Flotation cell mechanisms are started and stopped locally at the field stop/start station located adjacent to the cell.

The compressors are only able to be started and stopped locally at the field stop/start station and are under the control of the vendor controller package, which senses load and starts the second unit or puts the compressor on idle, as required.

7.1 CrushingStart-up and shut-down of the crushing section is split into two PLC controlled group sequences. One covers services such as dust collection equipment and the other covers the crushing equipment (conveyors, screens and feeders).


7.1.1 Crusher Plant Services Start SequenceThis PLC controlled group sequence covers start up of Crusher plant services equipment. The sequence will be initiated from the SCADA screen by the operator clicking on the Crusher Plant Services sequence start button.


Drive Description Drive Number Sequence Step Delay

(sec)

Comment

Crusher area fan 10-FA-003 n/a Started simultaneously

HPGR & secondary screen area fan 10-FA-007

Crusher dust collector rotary valve 10-VV-001

Crusher dust collector 10-BH-001

Crusher dust collector ID fan 10-FA-017

HPGR & secondary screen dust screw feeder

10-FE-010



(sec)

Comment

HPGR & secondary screen dust col-lector rotary valve

10-VV-002

HPGR & secondary screen dust col-lector

10-BH-001

HPGR & secondary screen dust col-lector ID fan

10-FA-018


7.1.2 Crusher Plant Start-up SequenceThis PLC controlled group sequence covers start up of crushing equipment feeding the fine ore bin. The sequence will be initiated from the SCADA screen by the operator clicking on the Crusher Plant sequence start button.



(sec)

Comment

Secondary crusher feed bin feed con-veyor

10-CV-002 n/a

Fine ore bin feed conveyor 10-CV-003 5

Secondary screen 10-SC-001 5

Crusher magnet 10-MA-001 5

Crusher product conveyor 10-CV-001 5

Secondary cone crusher 10-CR-002 5



(sec)

Comment

Primary jaw crusher 10-CR-001 5

Secondary crusher feeder 10-FE-002 5 Start with control loop LIC1015 in manual mode at minimum output

Primary crusher feeder 10-FE-001 5 Start with control loop SC1002 at minimum output


7.1.3 Crusher Plant Shut-down SequenceThe PLC controlled function group shut-down sequence will be initiated from the SCADA screen by the operator clicking on the Crusher Plant sequence stop button.



(sec)

Comment

Primary crusher feeder 10-FE-001 n/a

Secondary crusher feeder 10-FE-002 Variable Stop at 20% on LIC1015

Crusher product conveyor 10-CV-001 60

Secondary screen 10-SC-001 40

Secondary crusher feed bin feed con-veyor

10-CV-002 60 Delay to empty conveyors

Stopped simultaneouslyFine ore bin feed conveyor 10-CV-003



(sec)

Comment

Crusher magnet 10-MA-001 n/a

The primary jaw crusher and secondary cone crusher must be stopped individually when the area operator confirms they are clear.


7.1.4 Crusher Plant Services Shut-down SequenceThe PLC controlled function group shut-down sequence will be initiated from the SCADA screen by the operator clicking on the Crusher Plant Services sequence stop button.



(sec)

Comment

Crusher dust collector ID fan 10-FA-017 n/a Stopped simultaneously

Crusher dust collector 10-BH-001

Crusher dust collector rotary valve 10-VV-001

Crusher area fan 10-FA-003

HPGR & secondary screen dust col-lector ID fan

10-FA-018

HPGR & secondary screen dust col-lector

10-BH-001



(sec)

Comment

HPGR & secondary screen dust col-lector rotary valve

10-VV-002

HPGR & secondary screen dust screw feeder

10-FE-010

HPGR & secondary screen area fan 10-FA-007


The Crusher Plant Services shut-down sequence should not be used if the Grinding and Gravity circuit is operating as the HPGR & secondary screen area fan and HPGR & secondary screen dust collector equipment is required to operate while the HPGR is running. The Crusher dust collection equipment may be stopped individually by the control room operator in “Manual” mode

7.2 Grinding and GravityStart-up and shut-down of the Grinding and Gravity section is split into two PLC controlled group sequences. One covers the gravity gold recovery equipment and the other covers the mill circuit feed and HPGR equipment.

7.2.1 Grinding and Gravity Services Start-up Procedure


The following services equipment items are started individually at the relevant point, during the Grinding and Gravity start up procedures:

Process water pump (70-PU-035)

Raw water pump (70-PU-033)

Gland water pump (70-PU-032)


7.2.2 Gravity Circuit Start-up ProcedureThis PLC controlled group sequence covers start up of equipment in the Gravity circuit. The sequence will be initiated from the SCADA screen by the operator clicking on the Gravity sequence start button.



(sec)

Comment

Gravity concentrate transfer pump 20-PU-065 5 Select duty/standby

Ensure suction and delivery pipes correctly connected in field.

XV2066 closed

Spinner tails pump 20-PU-080 5



(sec)

Comment

Spinner no 1

Spinner no 2

Spinner no 3

Spinner no 4

20-GC-005A

20-GC-005B

20-GC-006A

20-GC-006B

5 Simultaneous start

Primary jig no 1 20-GC-001 5 Field operator intervention re-quired to open hutch water valves and bleed airPrimary jig no 2 20-GC-002 5

Primary jig no 3 20-GC-003 5



(sec)

Comment

Gravity screen 20-SC-003 5 Field operator intervention re-quired to open spray valves

Primary jig no 1 feed valve open XV2017 0 Simultaneous open

Primary jig no 2 feed valve open XV2018

Primary jig no 3 feed valve open XV2019

Mill pump 20-PU-003 5 Select duty/standby

Cyclone pump 20-PU-004 5 Select duty/standby



(sec)

Comment

Centrifugal concentrator no 1 20-GC-004 5 Start with XV2046 closed.

Open XV2046 manually after completion of HPGR sequence start.


7.2.3 HPGR Start-up ProcedureThis PLC controlled group sequence covers start up of equipment in the HPGR circuit. The sequence will be initiated from the SCADA screen by the operator clicking on the HPGR sequence start button.



(sec)

Comment

Mill feed, seal & trommel spray water valve

XV2093 n/a Actuated valve opened

Ball mill 20-ML-001 5 Refer Outokumpu design docu-ment 7330-DD01 Rev0

Ball mill screen 20-SC-002 5 Open spray valves in field

Mill screen oversize conveyor 10-CV-006 5

Mill feed conveyor 10-CV-005 5

HPGR 10-CR-003 n/a



(sec)

Comment

HPGR feed conveyor 10-CV-004 10

Fine ore bin belt feeder 10-FE-003 5 Start in manual mode - minimum output

Flocculant dosing pump A/B 60-PU-043A/B 30 Select duty/standby

Feeds float feed thickener


7.2.4 HPGR Shut-down ProcedureThe procedure covers shut-down of the HPGR section. The PLC controlled function group shut-down sequence will be initiated from the SCADA screen by the operator clicking on the HPGR sequence stop button.



(sec)

Comment

Fine ore bin belt feeder 10-FE-003 n/a Delay to empty conveyor

HPGR feed conveyor 10-CV-004 100 Delay to empty conveyor

HPGR 10-CR-003 100 Delay to empty HPGR feed bin

Mill feed conveyor 10-CV-005 100 Delay to empty conveyor

Mill screen oversize conveyor 10-CV-006 100 Delay to empty conveyor


7.2.5 Gravity Shut-down ProcedureThe procedure covers shut-down of the Gravity section.

The PLC controlled function group shut-down sequence will be initiated from the SCADA screen by the operator clicking on the Gravity sequence stop button.



(sec)

Comment

Purge Mill Screen Gold Trap XV2001 & 2 n/a The operator selects a purge cycle through the controller

Ball mill screen 20-SC-002 15 Close spray valves in field

Primary jig no 1 feed valve close XV2017 0 Simultaneous closure

Primary jig no 2 feed valve close XV2018

Primary jig no 3 feed valve close XV2019

Mill pump 20-PU-003 0



(sec)

Comment

Primary jig no 1 20-GC-001 120 Simultaneous shut-down after jigs flushed.

Field operator intervention re-quired to close hutch water valves

Primary jig no 2 20-GC-002

Primary jig no 3 20-GC-003

Spinner no 1 20-GC-005A 20 Simultaneous shut-down

Spinner no 2 20-GC-005B

Spinner no 3 20-GC-006A



(sec)

Comment

Spinner no 4 20-GC-006B

Spinner tails pump 20-PU-080 5

Gravity screen 20-SC-003 5 Close spray valves in field

Centrifugal concentrator no 1 feed valve closed

XV2046 30 Delay to empty screen underpan

Centrifugal concentrator no 1 20-GC-004 30 Stop initiates a controlled shutdown and timed rinse



(sec)

Comment

Ball mill 20-ML-001 5 Refer Outokumpu design document 7330-DD01 Rev0

Mill feed, seal and trommel spray water valve close

XV2093 n/a

Flocculant dosing pump A/B 60-PU-043A/B 5

Cyclone pump 20-PU-004 5


7.2.6 Grinding and Gravity Services Shut-downThe following equipment items are stopped individually at the relevant point, during the shut-down procedure, if a prolonged shut down (longer than 15 minutes) is anticipated and the flotation and CIL AND Detox section are not operating:





7.3 Flotation

7.3.1 Flotation Services Start-upThe flotation blower (70-CP-002) is started individually at the relevant point, during the Flotation start up procedure:

If the grinding and gravity circuit is not already running, the following services equipment items are also started individually at the relevant point:





7.3.2 Flotation Start-up ProcedureThis procedure covers start up of services for the Flotation section. The procedure will be manually controlled, i.e. control room operator will start each item individually in “Manual” mode in conjunction with the field operator, who will confirm the selection of duty pumps and open manual (e.g. spray water) valves as required.


Drive Description Drive Number Comment

Open flotation cell launder sprays wa-ter valves

n/a Field operator action

Flotation cell no 1 30-FC-001 Field operator action





Flotation concentrate pump 30-PU-008 Select duty/standby



Flotation feed thickener underflow pump

30-PU-006 Select duty/standby

Start in recirculation mode (XV3013 open & XV3014) then reset valves if underflow dens-ity acceptable

May have been left running on circuit shutdown in recircula-tion mode (i.e. XV3013 open & XV3014 closed)



Frother pump 60-PU-041 Select duty/standby

Start in manual mode - min-imum output

Collector dosing pump 60-PU-038 Select duty/standby


Copper sulphate dosing pump A/B 60-PU-039A/B Select duty/standby




Flotation tail thickener underflow pump


Start in recirculation mode (XV4011 open & XV4013) then reset valves if underflow dens-ity acceptable

May have been left running on circuit shutdown in recircula-tion mode (i.e. XV4011 open & XV4013 closed)



Sand pump hopper dilution water valve

FCV4039 Place Sand Pump Delivery Slurry Density control loop in Remote Manual mode and fully open the sand pump hop-per dilution water flow control valve

Sand pump 1 40-PU-072 Select duty/standby

Sand pump 2 40-PU-073 Select duty/standby

Flotation tail pump 30-PU-007 Select duty/standby

Flotation tails concentrator 50-GC-009



Flocculant dosing pump B/E 60-PU-043B/E Select duty/standby

Feeds float tail thickener

Flocculant dosing pump C/D 60-PU-043C/D Select duty/standby

Feeds Concentrate thickener


7.3.3 Flotation Shut-down ProcedureThe procedure covers shut-down of the Flotation section. The procedure will be manually controlled, i.e. control room operator will stop each item individually in “Manual” mode in conjunction with the field operator, who will confirm the draining of duty pumps and close manual (e.g. spray water) valves as required.



Flotation feed thickener underflow pump

30-PU-006 Maybe left running on circuit shutdown in recirculation mode if XV3013 open & XV3014 closed








Flocculant dosing pump B/E 60-PU-043BE

Flocculant dosing pump C 60-PU-043C/D

Flotation tail pump 30-PU-007

Flotation tails concentrator 50-GC-009

Flotation tail thickener underflow pump

40-PU-013 Maybe left running on circuit shutdown in recirculation mode if XV4011 open & XV4013 closed



Sand pump 2 40-PU-073 Allow line to flush. Delay maybe shortened if DIC <= 1.00

Sand pump 1 40-PU-072

Open flotation cell launder sprays wa-ter valves


Flotation concentrate pump 30-PU-008

Close flotation cell launder spray water valves



7.3.4 Flotation Plant Services Shut-downThe flotation blower (70-CP-002) is stopped after the flotation cells are stopped, if a prolonged shut down (longer than 15 minutes) is anticipated.

If the grinding and gravity circuit or CIL circuits are not running, the following services equipment items are also stopped individually during the shut-down procedure:




7.4 CIL and Detoxdocument.doc Page 334

7.4.1 CIL and Detox Services Start-upThe following services equipment items are started individually at the relevant point, during the CIL and Detox start up procedure:

CIL LP blower (70-CP-003)

CIL water pump (70-PU-028)

Cyanide pump (60-PU-047)

If the flotation circuit is not already running, the following services equipment items are also star-ted individually at the relevant point:




The lime pump (60-PU-066) is normally left operating to avoid choking the ringmain pipeline. The CIL lime addition control loop is left in “Remote Manual” mode and the operator selects the open position time (seconds) of the pulsing CIL lime addition valve as zero. On start up, the control loop is set to ‘Remote Auto”.

7.4.2 CIL and Detox Start-up ProcedureThis procedure covers start up of the CIL section. The sequence will be manually controlled, i.e. control room operator will start each item individually in “Manual” mode in conjunction with the field operator, who will confirm the selection of duty pumps and open manual spray water valves as required.



CIL tails pump 90-PU-022 Dilution water valve must be opened manually by field oper-ator

Carbon safety screen 90-SC-014 Screen spray water must be opened manually by field oper-ator

Trash screen underflow pump 83-PU-079 Select duty/standby

Trash screen 80-SC-005 Screen spray water must be opened manually by field oper-ator



SMBS pump 60-PU-067 Select duty/standby


Copper sulphate dosing pump B/C 60-PU-039B/C Select duty/standby


Flotation concentrate thickener under-flow pump


ILR n/a System stopped or left in in-ternal recycle


7.4.3 CIL and Detox Shut-down ProcedureThe procedure covers shut-down of the CIL section. The procedure will be manually controlled, i.e. control room operator will stop each item individually in “Manual” mode in conjunction with the field operator, who will confirm the draining of duty pumps and close manual spray water valves as required.



Flotation concentrate thickener underflow pump

30-PU-010

ILR n/a System stops and goes into in-ternal recycle

Trash screen 80-SC-005 Screen spray water must be closed manually by field operator

Trash screen underflow pump 83-PU-079



Carbon safety screen 90-SC-014 Screen spray water must be opened manually by field operator

CIL tails pump 90-PU-022 Dilution water valve must be left opened to flush line

SMBS pump 60-PU-067

Copper sulphate dosing pump B/C 60-PU-039B/C


7.4.4 CIL and Detox Services Shut-downThe following equipment items are stopped individually at the relevant point, during the shut-down procedure, if a prolonged shut down (longer than 15 minutes) is anticipated:

CIL LP blower (70-CP-003)

CIL water pump (70-PU-028)

Cyanide pump (60-PU-047)

The lime pump (60-PU-066) is normally left operating to avoid choking the ringmain pipeline. The CIL lime addition control loop is set to “Remote Manual” mode and the operator selects the open position time (seconds) of the pulsing CIL lime addition valve as zero.


7.5 Acid Wash ProceduresThe acid wash system is not automated and operator monitoring and intervention is required at various times during the acid wash sequence.

The extent of calcium scaling of the carbon will dictate the required acid strength and acid wash period. It may be necessary to increase acid wash solution acid strength or extend the acid wash time if the carbon is badly fouled. If it is required to complete as many elutions as fast as possible to meet gold production targets, the acid wash time may be reduced or the acid wash step maybe omitted completely on occasion.

Once a complete batch of carbon is ready in the acid wash column, the operator can perform the acid wash procedure.


7.5.1 Acid Wash Pre-RinseClose acid wash column carbon filling valve.

Ensure acid wash pump delivery valve to the column is closed.

Ensure acid wash column floor drain, back drain and carbon outlet valves are closed.

Select which acid wash strainer is to be used and open selected strainer inlet and outlet valves.

Open acid wash column solution inlet valve.

Open acid wash rinse discharge valve and close acid wash recycle valve.

Open acid wash rinse water valve and check for rinsings flow at the CIL tails pump hopper.


Allow carbon to rinse for the required period.

Close acid wash rinse discharge valve and open acid wash recycle valve.

7.5.2 Acid WashCheck acid wash tank level and acid strength.

If fresh dilute acid solution is to be made-up, refer to section 7.5.6 before proceeding.

If the acid wash tank is to be topped-up, refer to section 7.5.7 before proceeding.

Open acid wash pump suction and delivery isolation valves.

Open acid wash pump delivery valve to the column.


Start acid wash pump and allow dilute acid to circulate for required period.

Stop acid wash pump and close acid wash pump delivery to column inlet valve.

Close acid wash pump suction and delivery isolation valves.

Open acid wash column back drain valve and allow acid in the column to drain back to the tank.

Close acid wash column back drain valve.

7.5.3 Post Acid Wash RinseOpen acid wash rinse discharge valve and close acid wash recycle valve.

Open acid wash rinse water valve and check for rinsings flow at the CIL tails pump hopper.


Allow to rinse for the required period and close acid wash rinse water valve.


7.5.4 Carbon Transfer to Elution ColumnClose acid wash column solution inlet valve and acid wash strainer inlet valves.

Open elution column carbon filling valve

Open selected elution column strainer inlet and outlet valves.

Ensure elution column carbon outlet valve is closed.

Close eluate to electrowinning cell valve at the inlet to the heat exchanger.

Open transfer water recycle valve at the inlet to the heat exchanger.document.doc Page 348

Open transfer water valves to acid wash column and carbon outlet...

Start transfer water pump.

Open acid wash column carbon outlet valve.

Allow carbon to transfer for the required period (i.e. until all carbon is transferred).

Close acid wash column carbon outlet valve.

Close transfer water valves to acid wash column and carbon outlet.

Stop transfer water pump.

Close elution column carbon filling valve.


Close transfer water recycle valve at the inlet to the heat exchanger.

Open eluate to electrowinning cell valve at the inlet to the heat exchanger.

Open acid wash column floor drain valve and allow transfer water in the column to drain to the spillage sump.

7.5.5 Acid Wash Solution Neutralisation and DisposalOpen acid wash sodium hydroxide addition valve.

Ensure elution sodium hydroxide addition valve is closed.

Start sodium hydroxide pump and run for the required period.


Ensure acid wash column solution inlet valve is closed.

Open acid wash pump delivery valve to the column and acid wash column back drain valve.

Open acid wash pump suction and delivery isolation valves.

Start acid wash pump and allow mixture to circulate back to the tank for the required period.

Check pH of acid wash tank contents is neutral or slightly alkaline.

Open acid wash disposal valve and close acid wash pump delivery to column valve and check for neutralised spent acid flow at the CIL tails pump hopper.

The acid wash pump will stop by interlock when the acid wash tank reaches a low level.


7.5.6 Dilute Acid Make upCheck acid wash tank is empty.

Open acid wash tank raw water addition valve and partially fill the tank.

Close acid wash tank raw water addition valve.

Start hydrochloric acid offload pump and run for the required period.

Stop hydrochloric acid offload pump.

Re-open the acid wash tank raw water addition valve and fill the tank.

Check acid wash tank level and dilute acid concentration.document.doc Page 352

7.5.7 Dilute Acid Top-upCheck acid wash tank level and dilute acid concentration.

Start hydrochloric acid offload pump and run for the required period.

Recheck acid wash tank level and acid strength.

Repeat acid addition if required.

Open acid wash tank raw water addition valve and fill the tank.

7.6 Elution Procedures


The elution system is not automated and operator monitoring and intervention is required at various times during the elution sequence.

Once a complete batch of carbon is ready in the elution column, the operator can perform the elution procedure.

7.6.1 Elution ProcedureEnsure elution column carbon filling valve is closed.

Ensure a spent eluate disposal valve is closed.

If fresh eluate solution is to be made-up, refer to section 7.6.2 before proceeding.


Check sodium hydroxide and cyanide concentrations in the eluate and if required refer to section 7.6.3 to correct them.

Select which elution strainer is to be used. Open strainer inlet and outlet valves.

Open recovery heat exchanger inlet and outlet isolation valves.

Open elution heater inlet and outlet isolation valves.

Ensure transfer water recycle valve at the inlet to the heat exchanger is closed.

Ensure electrowinning cell drain and decant valves are closed and cell is ready to start elution i.e. busbars connected, hood in place and ventilation (goldroom scrubber) system running.

Open elution pump suction and delivery isolation valves.


Start elution pump.

Switch on elution heater.

Switch on CIL electrowinning rectifier.

Monitor temperatures and differential pressures using installed gauges around the circuit.

Confirm eluant temperature reaches the set-point.

Monitor column pressure using the column pressure gauge and adjust pressure regulation valve at the outlet of the recovery heat exchanger if required.

Approximately 1-2 hours prior to the end of the allotted elution time, switch off the elution heater to allow column to cool.


Stop elution pump.

7.6.2 Fresh Eluate Make Up ProcedureCheck elution tank is empty.

Open elution tank raw water addition valve and partially fill the tank.

Close elution tank raw water addition valve.

Open elution sodium hydroxide addition valve.

Ensure acid wash sodium hydroxide addition valve is closed.



Stop sodium hydroxide pump.

Calculate required volume of cyanide solution to be added.

Record elution cyanide flowmeter totaliser reading.

Open elution cyanide valve and monitor elution cyanide flowmeter totaliser reading until the required volume of cyanide solution has been added.

Close elution cyanide valve.

Re-open elution tank raw water addition valve and fill the tank.

7.6.3 Eluate Concentration Correction Procedure


Check elution tank level and reagent concentrations. Proceed through the following steps as required.

Open elution sodium hydroxide addition valve.

Ensure acid wash sodium hydroxide addition valve is closed.


Stop sodium hydroxide pump.

Recheck eluate sodium hydroxide concentration.

Repeat if required.

Calculate required volume of cyanide solution to be added.document.doc Page 359

Record elution cyanide flowmeter totaliser reading.

Open elution cyanide valve and monitor elution cyanide flowmeter totaliser reading until the required volume of cyanide solution has been added.

Close elution cyanide valve.

Recheck eluate cyanide concentration.

Repeat if required.

If required, re-open elution tank raw water addition valve and fill the tank.


7.6.4 Eluted Carbon Transfer ProcedureClose elution heater outlet isolation valve.

Close elution strainer inlet valve.

If carbon is to bypass the regeneration kiln, open eluted carbon screen bypass valve, close the eluted carbon screen feed valve and switch on the regen carbon screen and open the carbon quench pan water valve.

If carbon is to be regenerated ensure eluted carbon screen feed valve is open and eluted carbon screen bypass valve is closed and check availability of space in the kiln feed hopper.


Open transfer water valves to elution column and carbon outlet.

Start transfer water pump.

Open elution column carbon outlet valve.

Allow carbon to transfer for the required period (i.e. until all carbon is transferred)

Close elution column carbon outlet valve.

Close transfer water valves to elution column and carbon outlet.

Stop transfer water pump.

7.6.5 Spent Eluate Disposal


Check space is available in the spent eluate tank.

Open spent eluate disposal valve.

Close recovery heat exchanger inlet valve is closed.

Start elution pump.

The elution pump will stop by interlock when the elution tank reaches a low level.

Close spent eluate disposal valve.

Open recovery heat exchanger inlet valve.


BENDIGO MINING LIMITED PROCESS CONTROL PHILOSOPHYBENDIGO GOLD PROJECT APPENDICES

28/04/23document.doc Appendix 1 Page 364


APPENDIX 1SCHEDULE OF ALARMS





Description AlarmCategory

BH-001 crushing area dust collector ID fan failure 3

BN-001 ROM bin high level 3

BN-001 ROM bin low-low level 2

BN-002 fine ore bin high level 3

BN-002 fine ore bin high-high level 2

BN-002 secondary crusher feed bin high level 2

BN-002 secondary crusher feed bin high-high level 2

BN-005 HPGR feed bin diverter gate valve 1 closed 3




BN-005 HPGR feed bin diverter gate valve 1 open 3

BN-005 HPGR feed bin high level 3

BN-005 HPGR feed bin high-high level 2

CR-001 primary jaw crusher high level 2

CR-001 primary jaw crusher motor current high 3

CR-002 secondary cone crusher high level 2

CR-002 secondary cone crusher motor current low 3

Crusher spillage sump flood warning 3




Crusher spillage sump high level 2

CV-001 crusher product conveyor belt drift switch A (head lhs) 3

CV-001 crusher product conveyor belt drift switch B (head rhs) 3

CV-001 crusher product conveyor belt drift switch C (tail lhs) 3

CV-001 crusher product conveyor belt drift switch D (tail rhs) 3

CV-001 crusher product conveyor belt rip detector A 3

CV-001 crusher product conveyor belt rip detector B 3

CV-001 crusher product conveyor pull wire switch A (walkway side) 2




CV-001 crusher product conveyor pull wire switch B (non-walkway side) 2

CV-001 crusher product conveyor start-up warning system 3

CV-001 crusher product conveyor underspeed switch 3

CV-002 secondary crusher bin feed conveyor belt drift switch A (head lhs) 3

CV-002 secondary crusher bin feed conveyor belt drift switch B (head rhs) 3

CV-002 secondary crusher bin feed conveyor belt drift switch C (tail lhs) 3

CV-002 secondary crusher bin feed conveyor belt drift switch D (tail rhs) 3

CV-002 secondary crusher bin feed conveyor pull wire switch A (walkway side) 2




CV-002 secondary crusher bin feed conveyor pull wire switch B (non-walkway side) 2

CV-002 secondary crusher bin feed conveyor start-up warning system 3

CV-002 secondary crusher bin feed conveyor underspeed switch 3

CV-003 fine ore bin feed conveyor belt drift switch A (head lhs) 3

CV-003 fine ore bin feed conveyor belt drift switch B (head lhs) 3

CV-003 fine ore bin feed conveyor belt drift switch B (head rhs) 3

CV-003 fine ore bin feed conveyor belt drift switch B (tail rhs) 3

CV-003 fine ore bin feed conveyor pull wire switch A (walkway side) 2




CV-003 fine ore bin feed conveyor pull wire switch B (non-walkway side) 2

CV-003 fine ore bin feed conveyor start-up warning system 3

CV-003 fine ore bin feed conveyor underspeed switch 3

CV-004 HPGR feed conveyor belt drift switch A (head lhs) 3

CV-004 HPGR feed conveyor belt drift switch B (head rhs) 3

CV-004 HPGR feed conveyor belt drift switch C (tail lhs) 3

CV-004 HPGR feed conveyor belt drift switch D (tail rhs) 3

CV-004 HPGR feed conveyor pull wire switch A (walkway side) 2




CV-004 HPGR feed conveyor pull wire switch B (non-walkway side) 2

CV-004 HPGR feed conveyor start-up warning system 3

CV-004 HPGR feed conveyor underspeed switch 3

FA-003 crusher area fan low air flow switch 1

MA-002 HPGR magnet hoist down limit switch 3

MA-002 HPGR magnet hoist up limit switch 3

MA-002 HPGR magnet trolley in limit switch 3

MA-002 HPGR magnet trolley out limit switch 3




MD-002 HPGR metal detector 1 metal detected 2

MD-003 HPGR metal detector 2 metal detected 2

Secondary crusher metal detector metal detected 2

Stormwater collection pond flood warning 3

Stormwater collection pond high level 2

CH-030 Ball Mill Screen feed box high 2

CV-005 mill feed conveyor belt drift switch A (head lhs) 3

CV-005 mill feed conveyor belt drift switch B (head rhs) 3




CV-005 mill feed conveyor belt drift switch C (tail lhs) 3

CV-005 mill feed conveyor belt drift switch D (tail rhs) 3

CV-005 mill feed conveyor pull wire switch A (walkway side) 2

CV-005 mill feed conveyor pull wire switch B (non-walkway side) 2

CV-005 mill feed conveyor start-up warning system 3

CV-005 mill feed conveyor underspeed switch 3

CV-006 mill screen oversize conveyor belt drift switch A (head lhs) 3

CV-006 mill screen oversize conveyor belt drift switch B (head rhs) 3




CV-006 mill screen oversize conveyor belt drift switch C (tail lhs) 3

CV-006 mill screen oversize conveyor belt drift switch D (tail rhs) 3

CV-006 mill screen oversize conveyor pull wire switch (non-walkway side) 2

CV-006 mill screen oversize conveyor pull wire switch (walkway side) 2

CV-006 mill screen oversize conveyor start-up warning system 3

CV-006 mill screen oversize conveyor underspeed switch 3

FE-003 fine ore bin belt feeder belt drift switch A (head lhs) 3

FE-003 fine ore bin belt feeder belt drift switch B (head rhs) 3




FE-003 fine ore bin belt feeder belt drift switch C (tail lhs) 3

FE-003 fine ore bin belt feeder belt drift switch D (tail rhs) 3

FE-003 fine ore bin belt feeder pull wire switch A (lhs) 2

FE-003 fine ore bin belt feeder pull wire switch B (rhs) 2

FE-003 fine ore bin belt feeder start-up warning system 3

FE-003 fine ore bin belt feeder underspeed switch 3

HP-001 mill pump hopper high level 3

HP-001 mill pump hopper low level 3




HP-002 cyclone pump hopper high level 3

HP-002 cyclone pump hopper high-high level 3

HP-002 cyclone pump hopper low level 2

HP-010 gravity concentrate surge tank high level 2

HP-010 gravity concentrate surge tank high-high level 2

HP-010 gravity concentrate surge tank low level 2

Jig feed distributor density high 3

Jig feed distributor density low 3




Primary cyclone feed density high 3

Primary cyclone feed density low 3

PU-003A mill pump A gland water low flow 3

PU-003B mill pump B gland water low flow 3

PU-004A cyclone pump A gland water low flow 3

PU-004B cyclone pump B gland water low flow 3

PU-005 mill spillage sump high level 2

PU-074 mill spillage sump 2 high level 2




XM-001 ball mill screen gold trap discharge valve 1 closed 3

XM-001 ball mill screen gold trap discharge valve 1 open 3

XM-001 ball mill screen gold trap discharge valve 2 closed 3

XM-001 ball mill screen gold trap discharge valve 2 open 3

Concentrate thickener underflow density high 3

Concentrate thickener underflow density low 3

Concentrate thickener bed level high 3

Concentrate thickener bed level low 3




CY-001 mill cyclone pressure high 3

CY-001 mill cyclone pressure low 3

CY-002 sand cyclone inlet pressure high 3

CY-002 sand cyclone inlet pressure low 3

CY-001 cyclone underflow launder high level 2

DB-001 jig feed distributor pressure high 3

DB-001 jig feed distributor pressure low 3

Flotation feed thickener underflow density high 3




Flotation feed thickener underflow density low 3

Flotation feed thickener bed level high 3

Flotation feed thickener bed level low 3

PU-006A float feed thickener underflow pump A gland water low flow 3

PU-006B float feed thickener underflow pump B gland water low flow 3

PU-007A flotation tail pump 1 gland water low flow 3

PU-007B flotation tail pump 2 gland water low flow 3

PU-009 flotation spillage sump 1 high level 2




PU-011 float concentrate spillage sump high level 2

PU-055 float feed thickener spillage sump high level 2

PU-077 flotation spillage sump 2 high level 2

PU-081 flotation tails sampler transfer sump high level 3

SC-003 gravity screen underflow chute discharge valve closed 3

SC-003 gravity screen underflow chute discharge valve open 3

Flotation tails thickener underflow density high 3

Flotation tails thickener underflow density low 3




Flotation tails thickener bed level high 3

Flotation tails thickener bed level low 3

Flotation tails to east flotation TSF dam pipeline pressure high 3

Flotation tails to east flotation TSF dam pipeline pressure low 3

HP-003 flotation tail pump hopper high level 3

HP-003 flotation tail pump hopper high-high level 3

HP-003 flotation tail pump hopper low level 3

HP-018 sand pump hopper low level 3




HP-018 sand pump hopper low-low level 2

PU-012 flotation tails thickener spillage sump high level 2

PU-013A float tails thickener underflow pump A gland water low flow 3

PU-013B float tails thickener underflow pump B gland water low flow 3

PU-072A sand pump 1A gland water low flow 3

PU-072B sand pump 1B gland water low flow 3

PU-073A sand pump 2A gland water low flow 3

PU-073B sand pump 2B gland water low flow 3




Sand pump discharge pipeline pressure A high 3

Sand pump discharge pipeline pressure A low 3

Sand pump discharge pipeline pressure B high 3

Sand pump discharge pipeline pressure B low 3

PU-015 goldroom spillage sump high level 2

PV-001 pan filtrate receiver high level 2

Smelting furnace hood high differential pressure high 3

CM-001 acid wash column high level 3




Flocculant system fault 2

HP-019 collector stand pipe low level 3

HP-020 frother stand pipe low level 3

HP-021 sodium hydroxide stand pipe high level 3

HP-022 hydrochloric acid stand pipe high level 3

HP-024 trash screen underflow hopper low level 3

HP-024 trash screen underflow hopper high level 3

HP-024 trash screen underflow hopper high-high level 2




hydrochloric acid sump high level 3

PU-048 reagents spillage sump 1 high level 2

PU-049 reagents spillage sump 2 high level 2

PU-075 flocculant spillage sump high level 3

TK-023 copper sulphate tank low level 3

Flotation blower low pressure air pressure low 3

Potable water jockey pump low flow 3

PU-032 gland water pressure low 2




PU-076 CIL water tank spillage sump high level 2

PV-003 plant air receiver pressure low 3

PV-004 mill air receiver pressure low 3

TK-019 raw water tank low level 3

TK-020 process water tank high level 2

TK-020 process water tank low level 2

TK-020 process water tank low-low level 3

PU-016 ILR spillage sump high level 2




CIL differential pH high 3

PU-018 CIL spillage sump high level 2

HP-017 ILR cell tail pump hopper high level 2

PU-030 electrowinning spillage sump high level 2

CIL tanks area HCN gas high 1

FA-012/013 CIL tanks area vent failure 1

FA-014/015/016 CIL tanks area vent failure 1

HE-001 elution heater discharge temperature high 3




Kiln package fault 2

PU-026 acid wash spillage sump high level 3

TK-013 elution tank high level 3

TK-013 elution tank low level 2

TK-013 elution tank low-low level 2

TK-014 acid wash tank high level 2

TK-014 acid wash tank low level 2

CIL/Detox area HCN gas high 1




Detox differential pH high 3

Detox differential pH low 3

HP-007 CIL tails pump hopper low level 2

PU-021 detox spillage sump high level 2

PU-022A CIL tails pump A gland water low flow 3

PU-022B CIL tails pump B gland water low flow 3


APPENDICES

document.doc Appendix 2 Page 393

APPENDICES

APPENDIX 2PIPING & INSTRUMENTATION DIAGRAMS


APPENDICES

REFERENCE DOCUMENTS & DRAWINGS


APPENDICES

Name Number Revision Source

CRUSHING AND SCREENING AREA 1475-P-051 1 Ausenco

HPGR 1475-P-052 1 Ausenco

GRINDING GRAVITY CIRCUIT - SHEET 1 OF 3 1475-P-053 2 Ausenco


GRINDING 1475-P-055 0 Ausenco

FLOTATION FEED THICKENER 1475-P-056 2 Ausenco

FLOTATION 1475-P-057 2 Ausenco

CONCENTRATE THICKENER 1475-P-058 1 Ausenco


APPENDICES

FLOTATION TAILINGS - SHEET 1 1475-P-059 2 Ausenco

FLOTATION TAILINGS - SHEET 2 1475-P-060 2 Ausenco

GOLDROOM GRAVITY AREA 1475-P-061 1 Ausenco

GOLDROOM SMELTING 1475-P-062 2 Ausenco

REAGENTS AND CONSUMABLES SHEET 1 OF 4 1475-P-063 1 Ausenco




SERVICES - WATER SHEET 1 1475-P-067 2 Ausenco


APPENDICES

SERVICES - WATER SHEET 2 1475-P-068 2 Ausenco

SERVICES - AIR 1475-P-069 2 Ausenco

GRAVITY CONCENTRATE LEACHING 1475-P-070 2 Ausenco

FLOTATION CONCENTRATE LEACHING SHEET 1 1475-P-071 2 Ausenco

FLOTATION CONCENTRATE LEACHING SHEET 2 1475-P-072 2 Ausenco

ACID WASH 1475-P-073 2 Ausenco

ELUTION 1475-P-074 2 Ausenco

CARBON REGENERATION 1475-P-075 2 Ausenco

ELECTROWINNING 1475-P-076 2 Ausenco


APPENDICES

CYANIDE DETOXIFICATION SHEET 1 1475-P-077 2 Ausenco

CYANIDE DETOXIFICATION SHEET 2 1475-P-078 2 Ausenco


FIRE WATER RETICULATION 1475-P-080 1 Ausenco

SERVICES - PROCESS WATER 1475-P-081 1 Ausenco

SERVICES - RAW WATER 1475-P-082 2 Ausenco

SERVICES - SAFETY SHOWER WATER (SW) 1475-P-083 2 Ausenco

SERVICES - CIL SPRAY WATER (CW) 1475-P-084 2 Ausenco

SERVICES - GLAND WATER (GW) 1475-P-085 2 Ausenco


APPENDICES

SERVICES - TRANSFER WATER (TW) 1475-P-086 0 Ausenco

SERVICES - INSTRUMENT AIR (IA) 1475-P-087 1 Ausenco


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