christopher greet

7/27/2019 Christopher Greet

1/14

Improving copper recoveryat Xstrata Coppers Ernest

Henry Concentrator by

changing the grindingchemistry

Chris Greet, Jessica Kinal, John Twomey and Matthew Peatey


2/14


3/14

Flow sheet


4/14

2002-2004: Ian Wark Research Institute conducted tests on site

with the Magotteaux Mill, but encountered problems with

copper activated pyrite.

September 2004: A SAG mill feed sample tested successfully.

April 2005: Confirmation study on new SAG feed sample.

April 2006: Further confirmation study on new SAG feed sample.

April 2008: Pilot plant trial.

November 2009: Plant trail commences.

Project History


5/14

Laboratory results:

Pulp chemistry

Media pH Eh, mV (SHE) DO, ppm EDTA Fe, % EDTA Cu, %

Forged18% Cr30% Cr

10.910.910.9

-2393110

0.00.40.6

1.60.20.2

0.080.100.09


6/14

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

65.0 70.0 75.0 80.0 85.0 90.0 95.0 100.0

Cu recovery, %

Cugrade,

%

Forged 18% Cr 30% Cr

TestRecovery, % Dilutent grade

Cu Au Au, ppm Mo, ppm IS, % NSG, %

Forged18% Cr30% Cr

85.688.887.2

65.770.465.3

5.45.25.5

143615521528

18.314.47.6

38.442.349.1

Laboratory results:

Cu/Au metallurgy


7/14

Cu rougher

cel ls 1 and 2

Cu rougher

cel ls 3 and 4

Cu rougher

cel ls 1 and 2

Cu rougher

cel ls 3 and 4

HiCr pi lot plant bal l mi l l in

closed circui t with cyclone

Main plant

Cu rougher cells 5 to 8 Cu rougher cells 9 to 12

Cu rougher cells 5 to 8 Cu rougher cells 9 to 12

Reagents

Reagents

Forged pi lot plant bal l mi l l

in closed circui t with

cyc lone

SAG mil l discharge

Rougher tai l ing

Cu rougher concentrate

Rougher tai l ing

Cu rougher concentrate

Surge

tank

Surge

tank

Pilot plant study:

Pilot plant flow sheet


8/14

Media Parameters

pH Eh, mV (SHE) DO, ppm EDTA Fe, % EDTA Cu, %

Forged18% Cr

10.310.1

-8354

0.030.02

0.050.03

0.10.1

Pilot plant study:

Pulp chemistry


9/14

Pilot plant study:

Metallurgical improvement

Statistical analysis of the 65 surveys of the pilot plant indicated:

2.81.8 percent increase in Cu recovery (>99 percent confidence)

1.30.8 percent increase in Cu grade (>95 percent confidence)

3.42.2 percent increase in Au recovery (>99 percent confidence)


10/14

Do nothing.

Convert the ball mill to high chrome grinding media:

Dump and replace with an initial charge of high chrome

Realise benefits earlier

On/off trial

Logistical nightmare for a mill of this size

Media delivery at end of year

Purge by top-up

Nominally 8 months to purge the mill

Compare before and after

Supply earlier

Plant trial:

The options


11/14

Plant trial:

Dumping a mill without a hatch!


12/14

Media Parameters

pH Eh, mV (SHE) DO, ppm EDTA Fe, % EDTA Cu, %

Forged18% Cr

11.511.2

7598

0.61.9

0.640.27

0.660.26

Plant trial:

Pulp chemistry


13/14

Plant trial:

Cu recovery improvement

75

7779

81

83

85

87

89

91

93

95

0.05 0.10 0.15 0.20 0.25 0.30 0.35

Feed copper grade, %

Copperrecovery,

%

Forged Chrome Linear (Forged) Linear (Chrome)

0

10

20

30

40

50

10 100 1000

Size, micron

CuD

istributioninFinalTailing,

%

Forged 18% Cr

The copper recovery increased by 2.4 0.8 percent, with greater than 99percent confidence, which would increase the potential metal value by

$12,941,000 USD per annum.


14/14

Conclusions

The experimental approach adopted was designed to minimise risk to the

plant. In all three phases of the work it was noted that a change fromforged steel to high chrome grinding media resulted in:

A shift in the ball mill discharge Eh to more oxidising pulp potentials;

An increase in the dissolved oxygen content of the pulp; and

A reduction in the percentage of EDTA extractable iron.

The pulp chemical changes were due to the change in grinding media can

be directly linked to improved copper and gold recoveries in the

laboratory and pilot plant studies.

In the plant trial the improvement in the copper recoveries was at least1.6 percent due to improved fine chalcopyrite recovery.

The work demonstrates that using a robust laboratory schedule such as

the Magotteaux Mill can be used effectively to predict plant performance.

christopher greet

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