Modern Process Mineralogy:Two Case Studies

N.O. Lotter, L. Kormos, J. Oliveira,

D. Fragomeni, E. Whiteman

Xstrata Process Support

MEI Conference Nickel ’10, Falmouth, June 2010

2

XPS Groups – Sudbury, Ontario

Process Control - Identify and deliver robust process control technology and engineering solutions to achieve ‘Operational Performance Excellence.’

Process Mineralogy - Design, implement and optimize mineral processing flowsheets by matching the flowsheet to the mineralogy. Testwork, modeling and plant support to maximise operations efficiency.

Extractive Metallurgy – Provide specialized extractive metallurgy services (hydro-and pyrometallurgical). Flowsheet/project development using modeling and piloting, new process development and plant optimization.

Materials Technology – Improve the reliability of critical equipment through appropriate implementation of proven materials engineering practices at essential stages of design, procurement and operation.

“Adding Value… Reducing Risk…”

3

Process Mineralogy

Process

Mineralogy

Sampling & Statistics

Mineral Processing Mineralogy

4

Process Mineralogy

• Methodologies

• Representative Sampling

• Geometallurgical Unit Definition

• High Confidence Flotation Testing

• Factorial Design of Experiments

• Response Surface Modelling

• Mini Pilot Plant Campaigns

• Quantitative Mineralogy (QEMSCAN + EPMA)

5

Case Studies

• Flowsheet Development at Nickel Rim South

• Process Diagnosis at Raglan

CASE STUDY 1:

NICKEL RIM SOUTH

7

Location

Mill

Smelter

60 km

Nickel Rim

South

8

Nickel Rim South Mine

• Discovered in 2001

• 100% Xstrata Nickel ownership

• 9.6 Mt at 1.57% Ni, 2.85% Cu, 1.20g/t Pt, 1.35g/t Pd, 10.2g/t Ag, 0.46g/t Au

9

Objective

• Flowsheet Design

• New concentrator

• Strathcona Mill

• Strathcona Mill retrofit

• Testwork developed over several years as exploration program progressed

10

Methodology

• Define and characterise geometallurgicalunits

• Quantitative mineralogy

• High confidence flotation

• Mini Pilot Plant campaigns

11

Geometallurgical Units

Upper Footwall Mineralization

12

Comparison of Geomet Textures

Main Zone Footwall Fringe Zone

Pentlandite

Chalcopyrite

Bornite

Plagioclase

Epidote

Cpy average size: 348µm Cpy average size: 122µm

13

Flotation Testing of Geomet Units

1

2

3

C1

C2

C3

Tailings

1st Ro

2nd Ro

Scav

1 Lime, PIBX, Dowfroth 250

2 PIBX

3 Sulphuric Acid, Copper Sulphate, PIBX

14

Flotation Testing of Geomet Units

Upper Footwall

Main Footwall

Fringe Footwall

Contact Sublayer

Contact FootwallBreccia

Low Sulphur PGM

Ni+Cu Rougher Grade vs Ni Recovery

5

10

15

20

25

30

35

0 20 40 60 80 100

% Ni Recovery

% Ni + Cu Grade

Po-rich Po-poor

+Mg

15

Impact of CMC on Sublayer Ores

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20

Flotation Time, min

Ni Recovery %

Footwall Breccia Sublayer Breccia Sublayer Breccia w CMC

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New Concentrator Concept

Flash

Rougher

155µm

to

283µm 53µm

to

155µm 38µm

Regrind

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Staged Grind Flowsheet –Improvements over Strathcona

5.5 5.1

15.5

10.5

22

16.9

23.7 23.6

0

5

10

15

20

25

Ni Cu Pt Pd

% Recovery Improvement

Fringe

Low Sulphur PGM

These ore types represent only 10% of total resource

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Strathcona with Cu Pre-Float

Footwall Ore Contact Ore

Cu Pre-float Conc

Pri Ro Conc

Sec Ro Conc

Scav Conc

Scav Tails

P56 75µm P56 75µm

5.9

2.01.7

1.3

0

1

2

3

4

5

6

7

Ni Cu

% Recvoery

50/50

25/75

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Flowsheet Demonstration

• Each flowsheet option was demonstrated in the MPP

• Primarily from drill core samples

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Ni Rim South - Conclusions

3 retrofits recommended to Strathcona

• Cu Pre-float to minimise Ni and Cu losses

• Introduction of a CMC system to treat Sublayer ores

• Additional Cu/Ni separation capacity to allow for over 80% Cu recovery to Cu concentrate and allow for increased FW tonnages

• Metallurgical programme assisted by quantitative mineralogy was completed 2 years prior to commercial mine production

CASE STUDY 2: RAGLAN SURVEYS

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Raglan – Key Mineralogy

Massive Sulphides

Net-Textured Sulphides

Disseminated Sulphides

serpentinepyrrhotitepentlandite chalcopyrite

Massive Sulphides Net-Textured Sulphides Disseminated Sulphides

Pentlandite 291 78 68

Chalcopyrite 106 43 36

Pyrrhotite 386 68 60

Sulphide Grain Sizes

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Commissioned Flowsheet

Rougher Flotation

Final Concentrate

Final TailingsScavenger Flotation

Autogenous Mill

Secondary Mill

Rougher Flotation

Final Concentrate

Final TailingsScavenger Flotation

Autogenous Mill

Secondary Mill

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Comparison of Surveys –Ni Fe Sulphide Liberation in Feed

50

55

60

65

70

75

80

1998 2000 2003 2008

Pentlandite Liberation in Rougher Float Feed Varies

+106

+53

+25

CS1-3

CS4+5

CS6

CS7

Liberated

Middling

Locked0

5

10

15

20

25

30

% Ni Fe Sulphide

Size Fraction

1998Liberated

Middling

Locked

+106

+53

+25

CS1-3

CS4+5

CS6

CS7

Liberated

Middling

Locked0

5

10

15

20

25

30

% Ni Fe Sulphide

Size Fraction

Liberated

Middling

Locked

+106

+53

CS1-2

CS3

CS4-5

CS6

CS7

Liberated

Middling

Locked0

5

10

15

20

25

30

% Ni Fe Sulphide

Size Fraction

Liberated

Middling

Locked

-212/+106

-106/+53

CS1-2

CS3

CS4-5

CS6

CS7

Locked

Middling

Liberated

0

5

10

15

20

25

30

% Ni Fe Sulphide

Size Fraction

Locked

Middling

Liberated

78.9%

69.6%

65.3%

76.1%

2000

2003 2008

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Ni Fe Sulphide Liberation in Rougher Tailings

0

5

10

15

20

25

30

35

40

1998 2000 2003 2008

Pentlandite Liberation in Rougher Tails Varies

+106

+53

+25

CS1-3

CS4+5

CS6

CS7

Liberated

Middling

Locked0

5

10

15

20

25

30

% Ni Fe Sulphide

Size Fraction

Liberated

Middling

Locked

+106

+53

+25

CS1-3

CS4+5

CS6

CS7

Liberated

Middling

Locked0

5

10

15

20

25

30

% Ni Fe Sulphide

Size Fraction

Liberated

Middling

Locked

+106

+53

CS1-2

CS3

CS4-5

CS6

CS7

Liberated

Middling

Locked0

5

10

15

20

25

30

% Ni Fe Sulphide

Size Fraction

Liberated

Middling

Locked

-212/+106

-106/+53

CS1-2

CS3

CS4-5

CS6

CS7 Locked

Middling

Liberated

0

5

10

15

20

25

30

% Ni Fe Sulphide

Size Fraction

Locked

Middling

Liberated

39.2%

8.0% 7.4%

5.9%

1998 2000

2003 2008

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Changes from 1998 Survey

Rougher Flotation

To Final Concentrate

Final Tailings

Scavenger Flotation

Autogenous Mill

Secondary Mill

To Final Concentrate

Regrind Mill

Rougher Flotation

To Final Concentrate

Final Tailings

Scavenger Flotation

Autogenous Mill

Secondary Mill

To Final Concentrate

Regrind Mill

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Concluding Remarks

• Regular surveying identified flowsheetingopportunities

• These were implemented

• Grade and recovery maintained or improved

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Acknoledgements

Xstrata Nickel, for permission to publish this paper