Process Mineralogy Application October 26 2012 Joe Zhou

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Process Mineralogy and Application inMineral Processing and Extractive Metallurgy

Joe Zhou

Joe Zhou Mineralogy Ltd, Canada

[email protected]

1st International Metallurgical Conference Peru

October 26, 2012

Lima, Peru

2010-present: Joe Zhou Mineralogy Ltd, Canada

Principal Consultant & Director

2007-2010: JKTech/University of Queensland, Australia

Manager Mineralogy Consulting & MLA Solutions

Manager

2001-2007: SGS Lakefield Research, Canada

Mineralogy Group Manager & Senior Mineralogist

1994-2001: AMTEL, Canada

Senior Mineralogist

1979-1994: University of Science and Technology of China

Assistant, Lecturer & Associate Professor

About the Presenter


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Topics

Introduction: Why mineralogy?

Mineralogy: Objectives & Roles

Common mineralogical factors

and investigative techniques

Case studies

Summary

If better is possible, good is not enough1

Introduction Why Mineralogy?


How to reduce sulfur content in Mt concentrate

and increase Au & Ag recoveries?

1. Grade: Fe 46%, S 21%, Cu 0.25%,

Au 1.0g/t, Ag 13.0g/t.

2. Fe: 49.8% in Mt, 23.7% in Py & Mar,

6% in Po.

3. S: 88% in Py & Mar, 10% in Po.

1. Recoveries of Cu, S and Fe good.

2. Au and Ag in Cu Conc are 10g/t and

230g/. Low 22% and 28% recoveries.

3. S content of Mt conc is too high (1.0-

4.0%, sometimes 8%). To be reduced

to


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If better is possible, good is not enough

Why these liberated coarse Cp & Mo grains are not floated?

500m

A

900m

B

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Is bioleaching required for this ore (65g/t Au, 90% gold liberated at 200m grind)?

4


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Prediction

- Response of a new ore to various processes and most likely processing

options

- Estimated recovery of valuable minerals & grade of concentrate

- Potential mineralogical factors affecting ore processing & metal extraction

Trouble-shooting

- Deportment of valuable minerals and deleterious elements in concentrate

& tailings

- Cause for valuable losses & opportunity for recovery improvement

- Cause for high reagent consumption and opportunity for reagent

consumption optimization

Mineralogy: Roles & Objectives


30 um

Flotation(?)

&

Mineralogy: Roles & ObjectivesPrediction


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Au

1 2 4

More free-milling More refractory

Liberated,

coarse-grained

Locked,

medium-grained

Locked,

fine-grained

Locked,

submicroscopic

Gravity,

Flotation,

Cyanidation

Fine grinding

Cyanidation

Flotation &

Preoxidation

Flotation,

Fine grinding

Preoxidation &

Cyanidation

Pre-oxidation

& Cyanidation

Flotation


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locked

30 um

Flotation(?)

&


Prediction


0

5

10

15

20

25

30

0-1 0 1 0-20 2 0-40 4 0-60 6 0-80 80-10 0 100-120

Distribution(%)

Grain Size (m)

Size Distribution of Liberated Gold

Gravity recoverable gold

Flotation recoverable gold

Cyanide recoverable gold

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Mineralogy: Roles & ObjectivesTrouble shooting

Grinding

Flotation

Cyanidation

Regrind

(P80=33m)

Gravity

ConcentnGravity Conc

Flotn ConcFlotn Tail

Gravity Tail

CN Tail

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Simplified process flowsheet for a Au-Ag ore:


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-Quartz

3

13-18% of lost goldPy

2

12-22% of lost gold

1

60-75% of lost gold


Trouble shooting

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Mineralogy: Roles & ObjectivesGeomet modeling

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(Ref: R. Baumgartner et al, 2011: Building a Geometallurgical Model for Early-Stage Project Development

A Case Study from the Canahuire Epithermal Au-Cu-Ag Deposit, Southern Peru)


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1. Liberation/locking

2. Association

3. Grain size

4. Surface chemistry

5. Coating & rimming

6. Cyanicides & oxygen consumers

7. Preg-robbing (c-matter & more)

8. Refractoriness (submicroscopic gold & silver)

9. Slow-dissolving gold & silver minerals

10. Other deleterious minerals/toxic elements (As, Hg, asbestos)

11. Gangue mineralogy (clays & acid-forming minerals)


Mineralogy: Major Factors

Mineralogy: Commonly Used Techniques


Category Technique Technique Application MDL

Qua lita tive/S emi-Quant OM Optical MicroscopyMineral ID & qualitative/semi-quant

mineral analysis of bulk samplesHigh (%)

ADIS Automated Digital Image System High (%)

XRD X-ray Diffracton High (%)

SEM Scanning Electron MicroscopyMineral ID & qualitative/semi-quant

elemental analysis of individual particlesHigh (%)

MLA Mineral Liberation Analyser Low (%)

QEMSCANQuantitative Evaluation of Materials

by Scanning Electron MicroscopyLow (%)

EPMA Electron Probe Microanalysis Low (ppm)

PIXE Proton-induced X-ray Emission Low (ppm)

D-SIMSDynamic Secondary Ion Mass

SpectrometryLow (ppm-ppb)

LAM-ICP-MS

Laser Ablation Microprobe

Inductively Coupled Plasma Mass

Spectrometry

Low (ppm-ppb)

Synchrotron Synchrotron Radiation Light Source Low (ppm-ppb)

TOF-LIMSTime of Flight Laser Ion Mass

SpectrometryLow (ppm)

TOF-SIMSTime of Flight Secondary Ion Mass

SpectrometryLow (ppm)

XPS X-ray Photon Spectrometry Surface analysis of bulk material Low

Surface Analysis

Surface analysis of bulk material &

individual particle

Mineral ID & qualitative/semi-quant

mineral analysis of bulk samplesSemi-Quant

QuantitativeQuantitative mineral analysis of bulk

samples and individual particles

QuantitativeQuantitaive elemental analysis of

individual particles


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About the ore:

o Location: North Finland

o Grade & reserves: ~4.7g/t Au; probable reserves

of3.2 million ounces

o Small amounts of sulfide minerals (apy, py, cpy,

po, sph, gn, bo)

o Initial testwork showed very low gold recovery

by cyanide leaching

Case Study: Refractory Gold Ore


Processing how to extract gold?

o Fine grinding?

o Gravity?

o Flotation?

o Conventional cyanidation or pre-treatment?



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Gold deportment:

Gold occurs mainly as fine-grained inclusions and

submicroscopic gold in the lattices of sulfide

minerals (arsenopyrite and pyrite): ~75% of the

gold in arsenopyrite and 23% in pyrite.

Free gold


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Comments/recommendations :

Fine grinding? Yes

Gravity concentration? o

Flotation? Yes

Conventional cyanide leaching? o

Pre-oxidation? Yes



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Plant flowsheet:

Flotation + Pressure oxidation + Carbon-in-leach circuits.



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Liberated galena & dyscrasite:

Case Study: Ag-Pb-Zn Ore

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2

Dy

Silver minerals associated with gangue:


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3

4

Apy


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Conclusions:

Silver occurred mainly as freibergite, dyscrasite, pyragyrite and galenawith a moderate amounts of acanthite & native silver.

Silver in Pb Tail (60 g/t Ag): 15% of the lost silver(or2.2% of headassay) was liberated and associated with Gn, and can be recovered in

lead circuit without further grinding.

Silver in Zn Tail (48 g/t Ag): 15% - 20% of the lost silver(or1.8% of

head assay) was locked in Gn, Sph and other sulphide minerals, and isrecoverable by flotation in zinc circuit.

A total of4% silver recovery is expected by optimizing the plantoperating conditions.


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Summary: Benefits of Using Mineralogy


Validate metallurgical results

Avoid unnecessary metallurgical testwork

Avoid overlooking mineralogical factors

Eliminate duplication of non-optimum processes from other operations

Ensure optimal or near-optimal flowsheet development

Ensure appropriate equipment selection

Avoid oversizing or undersizing of equipment

Reduce uncertainties and increase confidence in process design criteria

Determine mineralogical factors that may cause or may havecaused processing issues & provide recommendations for processdesign or optimization

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A process mineralogy study should be conducted:

Prior to the start or at early stage of a project as a predictive tool

Whenever it is needed as a trouble shooting tool

Exploration

Scoping study

Prefeasibility study

Feasibility study

Plant operation & process optimization


Summary: Benefits of Using Mineralogy

Acknowledgement

Thank you for your attention!

Questions?

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Documents

Process Mineralogy Application October 26 2012 Joe Zhou