process mineralogy application october 26 2012 joe zhou
TRANSCRIPT
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Process Mineralogy and Application inMineral Processing and Extractive Metallurgy
Joe Zhou
Joe Zhou Mineralogy Ltd, Canada
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?
If better is possible, good is not enough2
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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Introduction Why Mineralogy?
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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Introduction Why Mineralogy?
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Is bioleaching required for this ore (65g/t Au, 90% gold liberated at 200m grind)?
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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
If better is possible, good is not enough5
30 um
Flotation(?)
&
Mineralogy: Roles & ObjectivesPrediction
If better is possible, good is not enough6
3
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(?)
&
Mineralogy: Roles & Objectives
Prediction
If better is possible, good is not enough
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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If better is possible, good is not enough
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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If better is possible, good is not enough
-Quartz
3
13-18% of lost goldPy
2
12-22% of lost gold
1
60-75% of lost gold
Mineralogy: Roles & Objectives
Trouble shooting
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If better is possible, good is not enough
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)
If better is possible, good is not enough11
Mineralogy: Major Factors
Mineralogy: Commonly Used Techniques
If better is possible, good is not enough12
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
If better is possible, good is not enough13
Processing how to extract gold?
o Fine grinding?
o Gravity?
o Flotation?
o Conventional cyanidation or pre-treatment?
If better is possible, good is not enough
Case Study: Refractory Gold Ore
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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
If better is possible, good is not enough
Case Study: Refractory Gold Ore
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Plant flowsheet:
Flotation + Pressure oxidation + Carbon-in-leach circuits.
If better is possible, good is not enough
Case Study: Refractory Gold Ore
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Liberated galena & dyscrasite:
Case Study: Ag-Pb-Zn Ore
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2
Dy
Silver minerals associated with gangue:
Case Study: Ag-Pb-Zn Ore
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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.
Case Study: Ag-Pb-Zn Ore
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Summary: Benefits of Using Mineralogy
If better is possible, good is not enough
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
If better is possible, good is not enough25
Summary: Benefits of Using Mineralogy
Acknowledgement
Thank you for your attention!
Questions?
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