Formulation and Plant Trial of a Mixed Collector Suite for

Eland PlatinumNorman O. LotterJorge Oliveira

Rebecca MonnapulaDominic FragomeniDee J. Bradshaw

Presentation to CMPOttawa, OntarioJanuary 2011

2

Summary

• Mixed Collector Theory

– Reviewed across 50 years of publications

– Consolidated and updated [Lotter and Bradshaw, 2009, 2010]

– New improved model proposed

• Eland Platinum engaged this model

– Baseline SIBX as single collector

– New Mixed Collector Exp 820 tested

– Demonstrated Performance Gains at Lab Scale– 2.1% PGE recovery gain

– Demonstrated Performance Gains at Plant Scale– 2.48% PGE recovery

– 16% relative concentrate grade

3

Mixed Collectors – an Updated Platform

Sulphide Flotation:-• Has used mixed collectors widely but seldom optimally

– Historic practice has a variable track record

• Review in 2009 summarised 50 years of research

• Authors wanted to advance the practice to a more predictive form [Lotter and Bradshaw, 2009 and 2010]

– New structure proposed

– Eland Platinum engaged this theory in a project

The formulation and use of mixed collectors in sulphide flotationN.O. Lotter a,*, D.J. Bradshaw bMinerals Engineering, 23, (2010), pp. 945-951a,* Xstrata Process Support, Sudbury, Ontario, Corresponding Authorb Julius Kruttschnitt Mineral Research Centre, Sustainable Mineral Institute, University of Queensland, Brisbane, Queensland, Australia

4

Mixed Collectors – the Benefits

Typical Outcomes:-

• Improved concentrate grade [15-25% relative]

– [Glembotskii, 1958; Bradshaw, 1997; Lotter and Bradshaw, 2011]

• Improved overall performance / A better grade/recovery curve [generally 2-5% more paymetals recovery]

– [Deng et al., 2010; Lotter and Bradshaw, 2011]

Synergy from Interactions

5

Mixed Collectors – How..

Reported Mechanisms:-• Improved flotation rate

– [Plaskin, 1954; Adkins and Pearse, 1992]

• Improved coarse particle recovery

– [Plaskin, 1954]

• Lower collector dosage requirement

– [Plaskin, 1954; Bradshaw, 1997]

• Best results from an optimised ratio

– [Critchley and Riaz, 1991; Valdiviezo and Oliveira, 1993; Mingione, 1984; Bradshaw, 1997; Lotter and Bradshaw, 2009; Deng, 2010]

• Less entrainment from improved froth structure

– [Bradshaw et al., 1998]

6

Mixed Collectors – the Modern Structure [Lotter and Bradshaw, 2009 and 2010]

Optimised mixed collectors best formulated by:-

• Mineralogy

– What minerals are present, and what we want to float

• Electrochemistry

– How these minerals react with collectors and and float

• Organic Chemistry

– Best selection of functional groups, chain lengths and structures

• Reagent Sudoku

– An expert system using 6-7 rules

• Factorial Design and Flotation Testing

– Accurately identifies and quantifies main effects and interactions

• Plant Trial

– Demonstrates the gains

7

Eland Platinum – the Opportunity

8

Eland Platinum – the Opportunity

• Commissioned Nov 2007

• Standard Design

• Commissioned on SNPX, changed to SIBX 2008

9

Geology

Understand the Orebody

10

Mineralogy - West Pit

EPMA - CharacteriseMineral Compositions

11

Mineral Compositions – West Pit

Composition of the Discrete PGMs varies widely

Electrochemical implications?

What reagent suite…?

Obviously a mixture…

0%

20%

40%

60%

80%

100%

1 2 3 4 5

Pt

Pd

Rh

Cu

Ni

Fe

S

12

Quantify Discrete PGMs

Distribution of Platinum Group Minerals

Eland UG2

30%

6%

23%

16%

13%

3%

1%

4%

1%

1%

0% 10% 20% 30% 40%

Pt Sulphide

Pt(PdNi) Sulphide

PtCu Sulphide

Ru(Rh) Sulphide

PtRh Sulphide

Pd Sulphide

Pt Arsenide

Pt Telluride

PtPd Telluride

Au-Ag

Discrete PGM Sulphides

Discrete PGM Amphoterics

13

Candidate Reagents

• Mineralogy

– What minerals are present, and what we want to float:

– Mostly discrete PGM sulphides, some PGM amphoterics, some electrum

– Wide range of compositions

• Electrochemistry

– Have to cover a range of potentials

– More than one type of collector needed

• Reagent Sudoku

– Selected two xanthates and a dithiocarbamate

– Total collector dose at plant was 240 g/t milled

– Factorial designed around this dose

14

Flotation Testing

TAILC1C2

C3

M1: 45% -75 microns

M2: 80% - 75 microns

F1

F2

TAILC1C2

C3

M1: 45% -75 microns

- 75 microns

F1

F2

TAILC1C2

C3

M1: 45% -75 microns

M2: 80% - 75 microns

F1

F2

TAILC1C2

C3

M1: 45% -75 microns

- 75 microns

F1

F2

Laboratory Scale Testing Used

an MF2 Format

15

Flotation Testing – West Pit

(-,-,-)

Xanthate 1

Xanthate

2

(+,+,+)

(+,-,-)

(-,+,+)

(-,+,-)

(-,-,+)

(+,-,+)

DTC

(+,+,-)

Replicated Factorial at High Confidence

16

Flotation Test Results

Platinum Recovery Responds Well

(So Do Pd and Rh)

Baseline SIBX

LCL

UCL

-3.0

-2.5

-2.0

-1.5

-1.0

-0..5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1 2 3 4 5 6 7 8 MC

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Flotation Test Results

• Main Effects

– Xanthate 2 had significant main effects on Pt, Pd, Rh(1.15 to 2.89% recovery)

• Interactions

– Xanthate 2/DTC had significant interaction (+0.69% Pd recovery)

• Predicted Outcome

– Mixed Collector Formulation would increase 4E PGE recovery by +2.1%

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Formulation of Mixed Collector Suite

• Three-component formulation called Exp 820

– Xanthate 1

– Xanthate 2

– Dithiocarbamate

– Formulated from modelling of factorial data

• Approached Senmin to manufacture trial batches

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Plant Trials Q4.09

• Campaign Format

– Eland Treats 5 Different Ore Types

– West Pit Ore is One of These

– On-Off Trial Had to Manage This

– Require Standard and Mixed Collector Runs Each Month

– Pooled Data Across Trial, First Test with ANOVA

• Changeover Rules

– Changeover Day Plus Next 2 Days Disqualified

• Conclusions to Be Made on West Pit Ore Only

• One-Week “Sighter” Trial First

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Sighter Trial – July 2009

• One-Week “Sighter” Trial on West Pit Ore

• Feed Grades

– PIBX 3.04

– Exp 820 2.93

• Tails Grades

– PIBX 0.91

– Exp 820 0.76

• Concentrate Grades

– PIBX 156.4

– Exp 820 131.9

Needed to change frother 0

0.5

1

1.5

2

2.5

3

3.5

Feed Tails

PIBX

Exp 820

Grade, g/t4E PGE

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Final Tailings

2.00 2.50 3.00 3.50 4.00 4.50

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

2.00 2.50 3.00 3.50 4.00 4.50

SIBX

Exp 820

Ore Milled, g/t PGE (4E)Final Tailings Grade, g/tPGE (4E)

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Final Tailings

0

5

10

15

20

25

30

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

Grade Bin g/t 4E

Frequency %

SIBX

Exp 820

0.86

0.88

0.9

0.92

0.94

0.96

0.98

1

Grade, g/tPGE

23

Final Concentrate

50 60 70 80 90

SIBX

Exp 820

0

50

100

150

200

250

300

350

50 60 70 80 90

SIBX

Exp 820

Recovery, % PGE (4E)Final Concentrate Grade, g/tPGE (4E)

24

Final Concentrate

0

5

10

15

20

25

30

35

100 125 150 175 200 225 250 275 300

Grade Bin g/t 4E

Frequency %

SIBX

Exp 820

145

150

155

160

165

170

175

180

185

190

Concentrate Grade g/tPGE

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Outcomes at Eland – West Pit

Successful Plant TrialsDemonstrate the Value

Mixed Collector Project at Eland Platinum Gains 2.48% PGE Recovery and 16.6% Higher Concentrate Grade

Differences Demonstrated at > 90% confidence level

Accurate Scale-up from Lab Work

Absolute Gain in 4E Recovery, %

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

4E PGE

Lab

Plant

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Conclusions

• Mixed Collector Theory Validated• Mineralogy powerfully informs reagent selection

• Laboratory scale testwork accurately predicted plant response

• Prototype Mixed Collector Exp 820 Successfully Formulated

• Clear Grade and Recovery Gains Demonstrated

• Further Work Anticipated• What advances can be made from here…?

27

Acknowledgements

The authors would like to thank the CMP for the

opportunity to present this work, and Xstrata Alloys for permission to use their project material. The authors would also like to thank their colleagues in Eland Platinum and Senmin for their support.

BuangMoloto

Rebecca Monnapula

Jules Aupiais