Development of an Innovative Copper Flowsheet at Phu Kham

M F Young and I Crnkovic Phu Kham Location in Laos Phu Kham Plant Layout

Plant Layout showing

• Primary Grinding • Rougher Flotation • IsaMill Regrinding Phu Kham Flowsheet

GYRATORY CYCLONES SAG MILL No.1

COARSE STOCKPILE

ROUGHER FLOTATION CELLS

ROUGHER PROCESS 1st CLEANER FLOTATION CELLS CONCENTRATE WATER CYCLONES DAM

ISAMILL 2nd CLEANER FLOTATION CELLS CONCENTRATE THICKENER

3rd CLEANER FLOTATION CELLS

CONCENTRATE TANK

CONCENTRATE FILTER

CONCENTRATE STOCKPILE Phu Kham Flowsheet

• 12.8 Mt/a of copper-gold bearing ore from the open pit • Plant Feed Grades are 0.75% Cu and 0.33g/t of Au and 3.8g/t of Ag • Concentrate quality is +25% Cu, 7 g/t of Au and 60g/t of Ag

• Primary Grinding Circuit contains – 34 ft × 18 ft (13MW) SAG mill – 24 ft × 39 ft (13 MW) ball mill • Regrinding Circuit contains – M10,000 (2.6MW) IsaMill

• Ore has fine locking of copper and • Ore requires regrinding rougher concentrate to 38 microns to make good quality final copper concentrate Cleaner Feed Performance

• IsaMill currently grinds from 90 microns to 38 microns • Cleaner feed performance at 38 microns and 25 microns • Laboratory Flotation Tests

Cleaner Grade-Recovery Profile For Cu-Afternoon Test 40

30

20 Cum Cu Grade

10

No Regrind (PM) With Regrind (PM)

0 20 40Cum Cu Recovery 60 80 100 New Phu Kham Flowsheet

• Cleaning Circuit was overloaded at times

• Fine grinding to improve concentrate quality, slowed flotation rate and increase frothing issues in the cleaner circuit, decreasing the performance of the cleaner circuit

• with froth washing was installed at the head of the cleaner circuit to increase cleaning capacity

• This new circuit allowed final concentrate to be produced from the IsaMill regrind product in one flotation cell and remove more than half the load from the existing cleaning circuit New Phu Kham Flowsheet

GYRATORY MILL CYCLONES CRUSHER SAG MILL No.1 BALL MILL

COARSE ORE STOCKPILE

ROUGHER FLOTATION CELLS

ROUGHER PROCESS 1st CLEANER FLOTATION CELLS CONCENTRATE WATER CYCLONES TAILINGS DAM

ISAMILL 2nd CLEANER FLOTATION CELLS CONCENTRATE JAMESON CELL THICKENER

3rd CLEANER FLOTATION CELLS

CONCENTRATE TANK

CONCENTRATE FILTER

CONCENTRATE STOCKPILE Layout of IsaMill and Jameson Cell Jameson Cell Flotation at Phu Kham Phu Kham Jameson Cell Grade-Recovery Curve Performance

• IsaMill Cyclone Overflow P80=20 microns • IsaMill Discharge P80=38 microns • Feed (Rougher Conc) Grade = 3-5% Cu

30.00

29.00

28.00

27.00

26.00 (%)

25.00 grade

Cu 24.00 Cyclone overflow only

23.00 Cyclone oveflow + IsaMill discharge 22.00

21.00

20.00 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% Cu recovery (%) Jameson Cell Size by Size Recovery on IsaMill Cyclone Overflow Stream

Phu Kham Jameson Cell Size-By-Size Recovery

Cu CYC OF 1 Cu CYC OF 2

100.00%

90.00%

80.00%

70.00%

60.00%

50.00%

Recovery % Recovery 40.00%

30.00%

20.00%

10.00%

0.00% 0 1020304050607080

Size Fraction New Cleaning Circuit Results

• Jameson Cell was initially commissioned on the regrind cyclone overflow • Cyclone Overflow was fine (P80=20 microns) and well liberated • Jameson Cell produced 25.5% to 27.5% Cu grade at 75% to 90% Cu recovery on this stream • Jameson Cell produced high recovery in all size fractions for this stream

• Jameson Cell then treated cyclone overflow plus IsaMill discharge • Jameson Cell still produced high grade copper concentrate at 26% to 29% Cu grade at 55% to 60% copper recovery • The recovery of the coarser size fraction was lower due to the locking and lower liberation in the size fractions Redox Measurements in Plant

Low Eh reduces the copper flotation performance Impact of Inert Grinding - Chalcopyrite

The Effect of Eh – Mt Isa Cu Ore

The critical importance of the grinding environment on fine particle recovery in flotation - Stephen Grano - 2009 Cleaner Feed Performance

The Effect of Aeration in Laboratory Float

Cu Grade-Recovery Curve-C1F 30

25

20

15 Cu % Grade 10

5 C1F Without Aeration C1F With Aeration RCOF

0 0 102030405060708090100 Cu Recovery % IsaMill Discharge Performance

The Effect of Aeration in Laboratory Float

Grade Recovery Curves (Total Cu) IMD 25

20

15

10

5

IMD Without Aeration IMD With Aeration

0 50 60 70 80 90 100 HYPERSPARGE Supersonic Gas Injection

Compact Ball Valve for Secure Fine Bubble Generation Isolation Able to generate much finer bubbles for fast gas transfer rates Solenoid Control Valve and flexible connection hose

Failsafe In Line Check Valve to prevent Slurry Spills Sturdy Barrel Union HyperSparge Connection for rapid maintenance a L

k High Pressure sparge

Spool Piece and High Pressure Supersonic Gas Seal for safe Injection Nozzle Low Pressure Insertion and for high intensity Ring sparge removal mass transfer

Gas Flow HyperSparge installed in IsaMill Discharge line Phu Kham – Effect of Aeration Plant Surveys

Phu Kham Jameson Cell Performance Before and After Aeration

Before Hypersparge After Hypersparge

28.0

27.0

26.0

25.0 Grade % Cu

24.0

23.0

22.0 40% 45% 50% 55% 60% 65% 70% 75% 80% Recovery % Cu Phu Kham – Effect of Aeration Plant Surveys

Phu Kham Jameson Cell Size-By-Size Recovery

Before HyperSparge After HyperSparge

100.00%

90.00%

80.00%

70.00%

60.00%

50.00% Recovery % Recovery 40.00%

30.00%

20.00%

10.00%

0.00% 0 1020304050607080 Size Fraction Summary

• IsaMill regrinds rougher concentrate to 38 micron to improve the final copper concentrate quality

• Cleaner feed performance at 38 microns is 25-28% Cu in final concentrate • and regrinding 25 microns can produce +30% Cu in final concentrate

• Jameson Cell installation was an innovative flowsheet change to removed load from cleaning circuit and increased plant capacity and decrease cleaner circuit frothing issues

• Aeration of Cleaner feed has improve performance and fines recovery and selectivity

• Jameson Cell has allowed the IsaMill to operate at Increase power to improve the circuit performance.