GRAVITY CIRCUIT Knelson Performance, Maintenance, Back to Basics. Drissa ARAMA, Plant Manager

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1 GRAVITY CIRCUIT Knelson Performance, Maintenance, Back to Basics Drissa ARAMA, Plant Manager

2 Morila Mine locality

3 Data for the record Commissioning Oct 2000 Official opening Feb 2001 First bullion bar poured was gravity gold Highest production record 1,052 koz in 2002 of which koz was from gravity Average feed grade in g/t Plant upgrade 2004 Randgold took over Morila operation Management in Feb 2008

4 Metallurgical process Oxide Crusher SAG Mill Ball Mill Classification Thickening Sulphide Crusher Primary & Secondary Recycle Crusher Gravity Recovery BWI 16 kwh/t Throughput 520 tph Avail % Recovery Oxide 96 % Sulphide 92 % CIL Tailings 40% Elution Electrowinning 60% Gravity Gold CIL Gold

5 Metallurgy - process flow Oxide Gravity Gold 25.4% Oxide CIL Gold 95% Oxide overall Gold 96.6% Oxide Ore 10 g/t Sulphide Ore 4.3 g/t Crushing SAG & Ball Milling & Gravity Carbon in Leach & Elution Tailings Storage Facility Sulphide Gravity Gold 40% Sulphide CIL Gold 87.0% Sulphide overall Gold 92%

6 Metallurgy - Knelson concentration 3xKnelson Concentrator KC XD48 G5 cone 450 t/hr Crushed Slag NaCN Lime Table Feed Tank By-pass concentrate to ILR Reactor Feed Tank H 2 O 2 Reagent Pot Gemini Table Gold for direct smelting Sump Table middlings & tails Reactor Drum 250 kg/h

7 Key production statistics Parameters Design data After upgrade Throughput rate 400 tph 520 tph Monthly capacity 250,000 t 350,000 t Head grade - oxide ore 10 g/t Head grade - sulphide ore 4.3 g/t 3.1 g/t Gravity recovery 40% 40% Leach circuit recovery 87% 87% Overall recovery 92% 92%

8 Production overview Head Grade (Au, g/t) Total Gold Produced (kg) Total Gold Produced (ounce) Gravity Gold (%) Gravity Gold (kg) 2000 * , , , , , , ,746 1,052, , , , , , , , , , , , , , , , , , , ,759

9 Recovery - Gravity vs Overall Jan-08 Feb-08 Gravity recovery (%) Overall plant recovery (%) 87

10 BACK TO BASICS MAINTENANCE

11 Finding and remedial actions KNELSON OPERATION

12 Operation Knelson feed PARAMETRES PREVIOUS CURRENT Panel screen size Combination of 2.0 and 4.0 mm Panel 2.0 mm N o of cyclone U/F to gravity (Targeting 03) N o of KC- on line Screen Feed Channeling Spray bars (Water pressure) 20% short-cut in oversize due to eccentric feed 02 x separate bars; 10 % short-cut in oversize 10 % short-cut in oversize due to central feed Equalized pressure: 5 % short-cut in oversize Screen Capacity 3 cyclones to KC 2 cyclones (Planned to Install Double Deck Screen for more cyclone)

13 Operation steel balls scats in concentrate Chinese Ball! Impact Gold Recovery

14 Finding and remedial actions MAINTENANCE UNIT STATUS

15 Maintenance leaking water around holding bolts

16 Maintenance silt holes

17 Finding and remedial actions OPERATING PARAMETERS

18 Machine setpoints flow Parameter Concentration flow Intermediate flow - Low flow Purge flow Setpoint USGPM 40 USGPM 200 USGPM Positive pressure 2 psia Incorrect fluidising water pressure = Poor recovery

19 Machine setpoints timers Parameter Feed off delay Drain time Purge time Positive pressure delay Setpoint 5 seconds 40 seconds 30 seconds 300 seconds Knelson total purge time reduced from 360 sec to 250 sec = increased Knelson running time

20 Machine setpoints pressure Parameter Operating pressure - Hi alarm Operating pressure - Hi shutdown Operating pressure - Lo alarm Operating pressure - Lo shutdown Setpoint 38 psia 44 psia 14.5 psia 13.8 psia*

21 Utilisation Utilisation takes motor-off flush time into account, but: Feed off delay = 5 sec Ramp down = 135 sec Drain #1 = 40 sec Purge = 30 sec Drain #2 = 40 sec Total = 250 seconds Then ideally, UTILISATION = (( )/3600)X100 = 93.05% Daily running time = 22.3hours

22 Other soft issues TURNED OVER New Engineering staff Alarmed override POOR SUPERVISION & SKILLS LEVEL Inspection/Cleaning Motivation COST SAVING Cone (Heart of the machines) leave for longer period TRAINING ON UNIT MAINTENANCE Back to Basics Reset all Set Points Re-effect passwords TRAINING ON UNIT OPERATION Back to Basics New Supervisor IMMEDIATE REPLACEMENT OF WEAR CONE Interlock between the mills and the Knelson

23 Performance GRG vs grade % GRG (%) Theoritical GRG (%) Plant Head (Au, g/t) High Grade Au, g/t

24 Performance GRG vs recovery Gravity recovery (%) Overall recovery (%)

25 Basic maintenance LUBRICATION : Correctly and on schedule as per planned maintenance schedule Bearing caps need greasing every 2 days Rotary Union needs greasing every week Bearings need greasing every 6 months Do NOT grease these items randomly and all at once. Only grease them when the rotor is turning and bearings are warm SILT EJECTION HOLES : Check (daily) and clean WATER STRAINER : Check (weekly) and clean CONCENTRATING CONES : Remove and clean as required (regular) REPLACE CONE : as required

26 Best practice cones cleaning Concentrating cones Monthly concentrating cone schedule by the operation Engineering staff to check and confirm if the cone is cleaned before to reinstall it Regular measurement of the cone wear Cone cleaning process Cleaned concentrating cone

27 Constraints KNELSON UNITS LOCATED IN CONFINED PLACE WITHIN THE GOLD ROOM Arrange simpler access CONTROL PANEL IS A STAND ALONE UNIT Integrate to SCADA or SEPARATE PC

28 Conclusion In summary apart from having good Gravity recovery ( ) the Morila Gravity Circuit performance dipped ( ) as a result of: Poor Supervision and Control on the units Poor engineering and operation practice Maintenance not as per KNELSON recommendation New Engineering staff not familiar with the UNITS Lack of training Lack of regular communication between Morila mine and Knelson Gravity Solutions

29 Continuous improvement BACK TO BASICS Operation & Maintenance TRAINING MODULES for new personnel including refresher training Re-enforce supervision, Zero Tolerance to deviations Technical staff to conduct PTO s on KC units Initiate Auto Flush

30 Continuous improvement Ensure all SETTINGS are correct Investigate additional FEED to GRAVITY CIRCUIT Overall utilization > 82%, if not investigate Target more >35% GRAVITY RECOVERY

31 Merci Beaucoup