Gekko Systems. Operations & Installations Gravity Devices The InLine Pressure Jig Rockwell Diamonds - March 2010

Transcription

1 Gekko Systems Operations & Installations Gravity Devices The InLine Pressure Jig Rockwell Diamonds - March 2010

2 TEMCO Tasmania, Australia

3 Pirquitas assembly for Argentina

4 The IPJ

5 Material Flow through the IPJ Feed enters the IPJ in the centre on top of the IPJ The material enters the distribution chamber and is distributed evenly through the IPJ As the material move further away from the feed point, the water velocity slows down to give fine heavy particles the chance to get down the hutch The pulsating action moves the heavy particles down to and eventually through the screen deck into the concentrate hatch The lighter particles gets pulsed on the top layer and moves from the centre to the outside discharge rim around the IPJ, and then discharged in the tailings launder

6 InLine Pressure Jig Cut-through

7 Why is the IPJ Different? Thick Bed Separation Circular Configuration Low Velocity Cross Flow Changing separation environment Reduces fines flow over to tails Saw Tooth Stroke High energy transfer to separation zone Moveable Sieve Particles accelerated from same starting point Low energy Low Interstitial Velocity

8 Low Velocity Cross Flow Thick Bed Separation Thick Bed

9 Saw Tooth Pulse IPJ PULSE CHART AND CYCLES PER MIN CYCLES STK LENGTH TOTAL STK LNTH TOTAL LNTH TRAV UP VELOC UP TIME DN VELOC DN TIME X cyc/min mm (d1) mm m/min m/s % m/s % % % 25 IPJ STROKE 0.15 STROKE VELOCITY d1 t1 cm t2 length (mm) time (min) velocity (m ) time (sec) dow n stk up stk

10 Typical Cross Flow Jigs Sinusoidal Stroke Inefficient time Low velocity

11 Ragging Old 2.65 S.G. Ragging New 3.2 S.G. Ragging Consistent cover / no hang up in Bed Blown/Pegged Beds

12 Water Balance Positive Water Flow Through Bed Hutch (dilution) Water Flow To Tail = Hutch Water Addition Water Flow From Con Line Feed m 3 /hr 120 Up-Flow m 3 /hr 18 Hutch m 3 /hr 50 Tails m 3 /hr 138 Concentrate m 3 /hr 32

13 Tails Flush ports (Diamond IPJ s) Diamond Jigs - Extra wash water in tails for flushing adds to the water balance

14 Installing the IPJ Piping IPJ Feed tph 10 m 3 /hr 24 %solids w/w 33 Velocity m/s 3.3 Critical V m/s ø NB Orifice on discharge lines provides internal pressure to assist in slurry transport Hutch m 3 /hr 20 Velocity m/s ø NB Tail tph 9.4 m 3 /hr 28.3 %solids w/w slope Velocity m/s ø NB Concentrate tph 0.6 m 3 /hr 15.4 %solids w/w 3.8 Velocity m/s 2.4 Critical V m/s ø NB 10 slope Concentrate Discharge Critical V m/s 1.8 Tails Discharge

15 Orifice Type Installations Bibiani - Ghana Con Mine - Canada

16 Installing the IPJ Direct Coupled Pumps Ensure that there is suitable head/ feed to provide pressure for the concentrate and tails transport

17 Installing the IPJ Rougher/Scavenger/Cleaner ALL IPJ discharge piping should be free draining with a minimum 10 slope Feed Feed Hutch Hutch Jig Tailings Jig Tailings Jig Tailings Rougher/Scavenger Decreased Grade Increased Recovery Combined Jig Con Final Jig Con Rougher/Cleaner Increased Grade Decreased Recovery

18 Golden Rules Operate above minimum pressure Maintain minimum allowable flow rate Ensure air is released from top of IPJ at all times Never leave ragging dry if steel is present as it will cement Maintain minimum hutch water flow to ensure positive water flow through bed

19 Advantages Recovery step changes Simplicity low foot print/high availability Low operating cost Security enclosed and lockable Mass Flow to Concentrate variable Feed Size 0-25mm offers flexibility

20 How to operate the IPJ The IPJ produces a continuous concentrate The yield recovered to sink controls the concentrate characteristics The desired yield to sink is determined using the recovery / yield curve

21 Typical Free Gold Grade Recovery Curve

22 Metal Recovery Gold, Copper, Silver, Slags Pre-concentration Base metal sulphides, diamonds, Cleaning Coal

23 Typical Diamond Size/Yield Recovery Data size mm mm mm mm mm mm Based on actual tracer recovery testwork

24 Angolan Diamond Balance Results

25 Aim of Operation The aim is to alter the jigs parameters to produce the yield required while obtaining the desired recovery.

26 IPJ Controls Manual Stand-alone System Instrumentation for local display at machine Local control panel for control of jig pulse characteristics and air bleed valve

27 IPJ Controls Automatic Stand-Alone Systems Bus shelter type control system Fully integrated PLC control with instrumentation Colour touchscreen interface Process control of all inlet and outlet streams

28 IPJ Controls Automatic Distributed SCADA Systems Fully integrated controls between IPJ and ancillary equipment Modular MCC containing all electrical switchgear and PLC SCADA interface distributed or standalone according to plant requirements

29 IPJ Parameters 7 main parameters to control the concentrate characteristics. Pulse Rate Stroke Length Down Stroke Speed Hutch Water Addition Ragging S.G. Air Release Screen Size

30 Pulse Rate GD6 Controller External/ Internal Switch toggles between the internal GD6 Potentiometer and the external PID controller Pot Increases the pulse rate using potentiometer Power on indicates power to the unit Delay the down stroke time Solenoid on indicates when the solenoid activates Analogue Input Pulse Input PROX SWITCH Analogue Output Pulse Output PV PID CV SOLENOID SP

31 GD6 Controller inside the IPJ Control Panel

32 Pulse Rate Local Controller (Manual IPJ s) PV Process Variable = No. of cycles that the IPJ is doing at that moment SP Set Point = No of cycles set in the controller - The controls used to alter the set point Enter used to lock in new readings to the set point A/M automatic/manual toggle (must be in automatic) SCADA Distributed control Same principle with advanced diagnostics Control modes set automatically during startup/shutdown of unit User friendly interface, increased flexibility Historical data - trending Integration into surrounding plant

33 Pulse Rate Proximity Switch The proximity switch detects when the ram should start another cycle The ram will then extend for the time dictated by the PID/GD6 controller After this time the ram will free fall until the proximity switch detects the block (light at rear flashes) and starts the cycle again The proximity switch has to be in the correct position to ensure that the ram does not bottom out or has short stroke

34 Pulse Shape Pulse Rate Adjustment

35 Rules of Thumb Increase pulse rate = increase conc. yield Decrease pulse rate = decrease conc. yield

36 Stroke Length Hydraulic Pump The VSD drive controls the speed of the motor. The motor can run from Hz The motor runs a small gear pump that pumps oil into the ram The faster the pump runs the more oil the ram receives over a given time and the longer the ram extends

37 Stroke Length Variable Speed Drive - Potentiometer The VSD is located within the control box and is controlled using the potentiometer on the front of the control box The potentiometer reading is from 1-10 and is scaled between Hz 10 = 100Hz 0 = 20 Hz (minimum frequency) Variable Speed Drive - Networked On automated units speed references for the hydraulic pump are set from the control system Operator sets the pump frequency as a percentage of maximum speed 100% = 100Hz 0% = 20 Hz (minimum frequency)

38 *fix graph Pulse Shape Stroke Length Adjustments

39 Rules of Thumb Increase stroke Length = increase conc. yield Decrease stroke Length = decrease conc. yield

40 Down Stroke D/S Control Valve The down stroke control is located on the hydraulic block on the leg of the jig The control valve reading is scaled from = fast down stroke (no restriction) 0 = slow down stroke (closed)

41 *Fix Graph Pulse Shape Down Stroke Adjustments

42 Rules of Thumb Increase down stroke speed = increase conc. yield Decrease down stroke speed = decrease conc. yield

43 Hutch Water Manual Systems A ball valve used to control the water addition to the hutch The magnetic flow meter indicates the flow of water in m3/hr Automatic Systems An actuated butterfly valve controls flow according the flowmeter input Hutch water can be set to control from actual flow, or calculated upflow through jig Hutch water addition to the IPJ1500/IPJ2400 has to be ~15/25 m3/hr greater that the water in the concentrate stream

44 Automated Flow Balance With flowmeters on all main streams it is possible to calculate all flows in, out and through the jig. By controlling hutch flow, it is possible to calculate the jig up-flow and optimise the overall yield and recovery of finer fractions

45 Air Release Valve Air Release The butterfly/pinch valve is opened and closed periodically to prevent a build up of air within the top of the jig The air is controlled by using a timer located on the control box The valve should be opened for short intervals and then as many times as is required to exhaust the air e.g. 3 seconds open, 45 seconds closed If the valve is left open for long periods the IPJ can experience a pressure drop which can cause the unit to bog

46 Air Release Air Release Timer For manual stand-alone systems, the timer is located on the control cabinet For automated systems, air release times are set through the control system The timer has a dual scale and is normally set during commissioning The on time and off time are changed by altering the two dials The timer controls the state of a 5/3 solenoid valve within the control cabinet which controls the state of the valve ( a 3/2 model is used for pinch valves) The timer should be optimised to ensure that water escapes from the air release valve after every cycle

47 Internal Pressure The internal pressure of the unit is monitored by the pressure gauge connected to the concentrate spool The operating pressure of the IPJ can vary between Kpa The unit contains a bursting disc to protect the metal work which will release at a nominal pressure of 210Kpa Automatic Pressure Control The IPJ control system integrates the pressure signal into its operations On high pressure alarms, valves on jig outlets are opened and the operator is alerted Automated variable orifices on tailings and concentrate lines are tied to the internal pressure and may be used to optimise the jig performance

48 Effect of Feed Rates Mass pull to concentrate is fixed on no change to pulse rate, stroke length or downstroke Hence a change of feed mass equates to increase in tails mass only Higher mass feed rate reduces % yield Increased valuables input however increase the concentrate grade in the smaller yield Lower recovery is expected particularly in the finer fractions for this condition

49 Screen Size The screen size is changed depending on the application. It is usually dependant on the yields to sink required Gold applications usually use a 2-4mm screen within mill circuits. Normally looking for higher grade concentrates The coarse feed applications (e.g. diamonds, tin, manganese) require screens that are coarser than the feed to provide a pure jigging environment They have closer S.G differentials and therefore require a very loose bed

50 Other Important Tips Other parameters that can be altered include: IPJ feed density (diamonds, coal, Iron ore etc.) Feed rate (tph) Size distribution of the feed (pre-screening) All of these parameters may require optimization and can be discussed with Gekko personnel The unit may bog at some stage put in a large sized dump valve

51 To achieve a Higher Grade conc Add higher SG ragging Increasing ragging depth Increase hatch water flow Decrease down stroke Decrease stroke length Decrease pulse frequency Increase feed rate

52 To achieve higher Recovery Lower the Ragging SG Lower the ragging depth Increase stroke frequency Increase stroke length Increase down stroke speed Decrease the hutch water flow Increase screen size Decrease feed rate

53 QUESTIONS?