geometallurgicalgeometallurgicalcharacterisation ... · 1/29/2013 2 3 • definition of...

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GeometallurgicalGeometallurgicalGeometallurgicalGeometallurgical CharacterisationCharacterisationCharacterisationCharacterisation

and Representative Metallurgicaland Representative Metallurgicaland Representative Metallurgicaland Representative Metallurgical

Sampling at Xstrata Process SupportSampling at Xstrata Process SupportSampling at Xstrata Process SupportSampling at Xstrata Process Support

45nd Annual CMP Conference January 22-24, 2013

L. Kormos, J. Sliwinski, J. Oliveira, G. Hill

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• Xstrata Process Support would like to thank Carpathian Gold and AGP Mining for their support and permission to present this work

Acknowledgements

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• Definition of Geometallurgy

• Methodology

– Choosing Geometallurgical Units – Options

– Representative Sampling

– Quantitative Mineralogy

– Metallurgical Testing

• Case Study – Rovina Valley Project - Carpathian Gold

Summary

Definition

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A cross disciplinary approach in which metallurgical performance of an ore is linked to intrinsic geological and mineralogical characteristics

Objective is to create a robust flowsheet able to treat the full range in variability and develop production strategies that maximise financial performance

Geometallurgy

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1. Statistical approach utilising the assay database and geological variables

Benefit: robust methodology if extensive database is available

Risks:

• Exploration databases are often limited to paymetals but a geometallurgical unit definition requires understanding of gangue minerals

• Scoping and pre-feasibility studies take place prior to the availability of extensive data sets

• Purely statistical methods will produce multiple populations which can require extensive testing and validation prior to consolidation into a smaller number of composites for metallurgical testing

Methodologies used in Industry

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Methodology used in Industry

2. Use of ore mineralogy, geology and spatial distribution of geological and mineralogical features along with review of relevant metallurgical data to define geometallugicalunits. Use of supporting statistics to confirm discrete populations

Benefit:

• Can apply at early stages of a project

• Cost effective

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Methodology continued

Parameters used in assessment:

Grade

Grade ratios (polymetallic ores)

Lithology

Mineralogy

Alteration

Structure

Grain Size

Hardness

Presence of deleterious elements or minerals

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• Proper sampling is key to ensuring that results of the geometallurgical study will reflect future performance

• Random sampling is not always practical

– Requirement for very large samples when test program may need only a fraction of the mass

• Non-random sampling is effective way of matching characteristics of metallurgical test samples to larger sample population

– Grade and grade distribution

– Lithology/alteration distributions

– Spatially representative

Representative Sampling

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Mineralogical Characterisation

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• Mineralogical characterisation using quantitative mineralogy (XPS uses QEMSCAN and EPMA)

– Define in-situ grain sizes

Testwork Program

97

72

84

60

127

103

72 6859

121

56

160

3124

36

19

43

28

0

20

40

60

80

100

120

140

160

180

GEOMET 1 GEOMET 2 GEOMET 3 GEOMET 4 GEOMET 5 GEOMET 6

Gra

in S

ize

(µm

)

Average Grain Sizes (µm)

sph

cpy

gal


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– Modal mineralogy

Testwork Program

Minerals

Chalcopyrite

Bornite

Chalcocite

Pyrite

Enargite/Tetrahedrite

Jarosite

Tetrahedrite

Other Sulphides

Chlorite

Quartz

Muscovite

Fe Al Clay

Kaolinite

Pyrophyllite

Orthoclase

Plagioclase

Zunyite

Fe Ti Oxides

Mn Oxide

Diaspore

Alunite

Barite

Phosphates

Other

()

UGM3

UGM2

UGM1

UGM0

Mass (%)

0 20 40 60 80 100

Minerals

Chalcopyrite

Bornite

Chalcocite

Pyrite

Enargite/Tetrahedrite

Jarosite

Tetrahedrite

Other Sulphides

Chlorite

Quartz

Muscovite

Fe Al Clay

Kaolinite

Pyrophyllite

Orthoclase

Plagioclase

Zunyite

Fe Ti Oxides

Mn Oxide

Diaspore

Alunite

Barite

Phosphates

Other

()

UGM3

UGM2

UGM1

UGM0

Mass (%)

0 20 40 60 80 100

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– Modal mineralogy

– Element deportments

Testwork Program

0%

20%

40%

60%

80%

100%

GEOMET 1 GEOMET 2

Ce DeportmentOther

Micas

Zircon

Apatite

Rutile/Ilmenite

Perovskite

Crichtonite

CaTiNb REE

Fe Synchysite

Synchysite0%

20%

40%

60%

80%

100%

GEOMET 1 GEOMET 2

Ce DeportmentOther

Micas

Zircon

Apatite

Rutile/Ilmenite

Perovskite

Crichtonite

CaTiNb REE

Fe Synchysite

Synchysite

Metallurgical Benchmarking

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• Use of same flowsheet, reagent suite and conditions so a direct comparison can be made between the geometallurgical units

• Flowsheet may be adjusted after the first phase, geometallurgical units are reviewed and may be consolidated prior to additional testing

Testwork Program

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Case Study:

Carpathian Gold

Geometallurgical Study

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Rovina Valley Gold Copper Project

• Located in west central Romania

• Mining District known as Golden Quadrilateral

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Site Visit

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• Site visit to review geology, work with project geologists to come up with a list of 5 preliminary geometallurgical units

• Spatial distribution, lithology, alteration, grade, grade ratios were the main criteria used

• Previous metallurgical data reviewed

• Representative composites created


Total Population vs. Metallurgical Composite

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Representative Samples – Head Grade

6576

277

0

1000

2000

3000

4000

5000

6000

7000

Total Geomet Population

Geomet Subsample Composite

Core Intersections

6576

277

0

1000

2000

3000

4000

5000

6000

7000



Core Intersections

0.790.82

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1



Au Grade (ppm)

0.790.82

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1



Au Grade (ppm)

1629 1673

0

200

400

600

800

1000

1200

1400

1600

1800

2000



Cu Grade (ppm)

1629 1673

0

200

400

600

800

1000

1200

1400

1600

1800

2000



Cu Grade (ppm)

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Representative Samples – Grade Distribution

0%

20%

40%

60%

80%

100%

0

10

20

30

40

50

60

70

80

Fre

qu

en

cy

Grade ppm

Au - Geomet Subsample Composite MET-27

0%

20%

40%

60%

80%

100%

0

10

20

30

40

50

60

70

80

Fre

qu

en

cy

Grade ppm

Au - Geomet Subsample Composite MET-27

0%

20%

40%

60%

80%

100%

0

200

400

600

800

1000

1200

Fre

qu

en

cy

Grade ppm

Cu - Total Geomet Population Ciresata Sediment

0%

20%

40%

60%

80%

100%

0

200

400

600

800

1000

1200

Fre

qu

en

cy

Grade ppm

Cu - Total Geomet Population Ciresata Sediment

0%

20%

40%

60%

80%

100%

0

500

1000

1500

2000

2500

Fre

qu

en

cy

Grade ppm

Au - Total Geomet Population Ciresata Sediment

0%

20%

40%

60%

80%

100%

0

500

1000

1500

2000

2500

Fre

qu

en

cy

Grade ppm

Au - Total Geomet Population Ciresata Sediment

0%

20%

40%

60%

80%

100%

0

5

10

15

20

25

30

35

40

45

Fre

qu

en

cy

Grade ppm

Cu - Geomet Subsample Composite MET-27

0%

20%

40%

60%

80%

100%

0

5

10

15

20

25

30

35

40

45

Fre

qu

en

cy

Grade ppm

Cu - Geomet Subsample Composite MET-27


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Representative Sampling – Alteration Distribution

0%

5%

10%

15%

20%

25%

30%

35%

0

500

1000

1500

2000

2500

NA VWK WK MOD INT PER

Quartz Stockwork - Total Geomet Population Ciresata Sediment

Number

Percentage

0%

5%

10%

15%

20%

25%

30%

35%

0

500

1000

1500

2000

2500


Quartz Stockwork - Total Geomet Population Ciresata Sediment

Number

Percentage

0%

5%

10%

15%

20%

25%

30%

35%

0

10

20

30

40

50

60

70

80

90

100


Quartz Stockwork - Geomet Subsample Composite MET-27

Number

Percentage

0%

5%

10%

15%

20%

25%

30%

35%

0

10

20

30

40

50

60

70

80

90

100


Quartz Stockwork - Geomet Subsample Composite MET-27

Number

Percentage

9 7 0

2

258

1

Alteration - Geomet Subsample Composite MET-27

A

PH

TRPH

SIL

PT

MACE

9 7 0

2

258

1

Alteration - Geomet Subsample Composite MET-27

A

PH

TRPH

SIL

PT

MACE

219184

4

53

6572

20

Alteration - Total Geomet Population Ciresata Sediment

A

PH

TRPH

SIL

PT

MACE

219184

4

53

6572

20

Alteration - Total Geomet Population Ciresata Sediment

A

PH

TRPH

SIL

PT

MACE

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Representative Sampling – Spatial Distribution

Top ViewTop ViewTop ViewTop View Section Looking WestSection Looking WestSection Looking WestSection Looking West

Modal Analysis

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Geometallurgical Unit Characterisation

Minerals

ChalcopyritePyritePyrrhotiteQuartzChlorite

MuscoviteOrthoclasePlagioclaseBiotite

AmphibolesKaoliniteEpidote/Zoisite

Other Silicate GangueCarbonatesFe Oxide/Spinels

Other

Su

rve

y N

ame

MET-32

MET-31

MET-30

MET-28

MET-27

Mass (%)0 50 100

Minerals

ChalcopyritePyritePyrrhotiteQuartzChlorite

MuscoviteOrthoclasePlagioclaseBiotite

AmphibolesKaoliniteEpidote/Zoisite

Other Silicate GangueCarbonatesFe Oxide/Spinels

Other

Su

rve

y N

ame

MET-32

MET-31

MET-30

MET-28

MET-27

Mass (%)0 50 100

Minerals

Chalcopyrite

Pyrite

Pyrrhotite

MET-32

MET-31

MET-30

MET-28

MET-27

Mass (%)0 2 4 6 8 10

Minerals

Chalcopyrite

Pyrite

Pyrrhotite

MET-32

MET-31

MET-30

MET-28

MET-27

Mass (%)0 2 4 6 8 10

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Copper and Gold

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Rougher Flotation Benchmarking

0

5

10

15

20

25

0 50 100

Go

ld G

rad

e

Gold Recovery

MET-27

MET-28

MET-30

MET-31

MET-32

0

5

10

15

20

25

0 50 100

Go

ld G

rad

e

Gold Recovery

MET-27

MET-28

MET-30

MET-31

MET-32

0

1

2

3

4

5

6

0 50 100

Co

pp

er

Gra

de

Copper Recovery

MET-27

MET-28

MET-30

MET-31

MET-32

0

1

2

3

4

5

6

0 50 100

Co

pp

er

Gra

de

Copper Recovery

MET-27

MET-28

MET-30

MET-31

MET-32

Is Consolidation Required?

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Geometallurgical Unit Review

0.05 0.1 0.15 0.2

MET 27

MET 28

MET30

MET31

MET32

Head Grade

0.05 0.1 0.15 0.2

MET 27

MET 28

MET30

MET31

MET32

Head Grade

0 10 20

MET 27

MET 28

MET30

MET31

MET32

Biotite

0 10 20

MET 27

MET 28

MET30

MET31

MET32

Biotite

0 10 20

MET 27

MET 28

MET30

MET31

MET32

Pyrite/Chalcopyrite Ratio

0 10 20

MET 27

MET 28

MET30

MET31

MET32

Pyrite/Chalcopyrite Ratio

0 10 20

MET 27

MET 28

MET30

MET31

MET32

Mass Pull

0 10 20

MET 27

MET 28

MET30

MET31

MET32

Mass Pull

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• Cu grade vs recovery are distinct (with exception of MET-27 and MET-28)

• Pyrite/chalcopyrite ratio is higher in MET-28, impacting mass pull and Cu recovery

• Cu grade at a given Cu recovery is linked to the pyrite/chalcopyrite ratio in MET-30 and MET-32

• Overall Cu recovery varies and are not specifically driven by head grade

• Filtration rates are very slow for MET-27 due to the high biotite content

• As a result – five geometallurgical units were allowed to stand as distinct entities

Geometallurgical Unit Review

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• Screening tests to evaluate primary grind size, reagent type, pH, viscosity modifiers and gangue depressants

– Use of benchmarking data, mineral grain size, modal analysis used as an input in the design of test program

• DOE program to optimise pH, collector dosage, collector type

• Locked cycle tests

Next Steps

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• Geometallurgical studies define range of mineralogical characteristics and metallurgical performance that can be expected from an orebody

• Definition of geometallurgical units is best achieved by teams consisting of project geologists and metallurgical/process mineralogy staff

• Creation of representative composites is of key importance

• Use of quantitative mineralogy combined with metallurgical testing can define the geometallurgical character of the deposit even at early project stages

Conclusions

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