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Process Diagnosis using Quantitative Mineralogy
L. Kormos1, J. Oliveira1, D. Fragomeni1, E. Whiteman1, J. Carrión De la Cruz2
1Xstrata Process Support 2Compañia Minera Antamina S.A.
42nd Annual CMP Conference January 19-21, 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 bymatching 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
• Design of Experiments
• Mini Pilot Plant Campaigns
• Quantitative Mineralogy (QEMSCAN + EPMA)
5
Case Studies
• Contamination of Copper Concentrates at Antamina
• Flowsheet Development at Nickel Rim South
CASE STUDY 1:
ANTAMINA BORNITE ZONE
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Antamina Mine Location
ANTAMINA
YANACOCHA
PIERINA
TOQUEPALACUAJONE
TINTAYA
MARCONA
CERRO DE PASCO
CERRO VERDE
8
Antamina Mine
• Open pit operation since May 2001
• Current Ownership: BHP-Billiton (33.75%), Xstrata (33.75%), Teck-Cominco (22.5%) and Mitsubishi (10%)
• 560 Mt Cu-Zn skarn deposit with minor Mo, As, Bi, Ag, Pb
• 8 ore types have been defined based on metal ratios
• Concentrator operates entirely by campaign
• Produces Cu, Zn, Mo and Pb-Bi-Ag concentrates
9
Antamina Mine
• Bismuth and Arsenic contamination of Cu Concentrates gives rise to substantial penalties
• Mining of an ore type known as the Bornite Zone is particularly problematic for producing contaminated concentrates
10
Objectives of Study
• Define bismuth and arsenic mineralogy in the Bornite Zone
• Species identification
• Element deportment
• Textures that may affect recovery to concentrates
• Provide information to geological and metallurgical teams who were required to develop a bismuth and arsenic rejection strategy
11
0 500 1000
Meters
X X X X X X
X X X X X X
X X X X X X
X X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X
SENW
EndoskarnCu, Mo
Indeterminate SkarnCu,Zn,±Mo,±Bi
Brown and Green Exoskarn
Cu, Zn, Ag, Bi
Green ExoskarnZn,Cu,Ag,Bi,Pb
Marble± Zn, ± Pb, ± Ag, ± Bi
Wollastonite-Bornite ExoskarnCu, Zn, Ag, Bi
Heterolithic BrecciaCu, ± Zn
Quartz Monzonite Intrusive Mo, Cu
Hornfels± Zn, ± Pb, ± Ag, ± Bi
Zn,Pb,AgAg
Pb Zn, Bi
Zn,Pb,Ag,Bi
Schematic Lithology and Metal Zonation
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Bornite Ore 11%Chalcopyrite Ore 89%
(4200m bench)
Cu Ore Zonation
13
Ore Characterisation Methodology
• A series of samples that spatially covers the deposit or zone
• A set of coarse particle composites
• A set of polished thin sections
• Use of quantitative mineralogy (QEMSCAN + EPMA) to map textures, define modal mineralogy, mineral compositions and element deportments
14
Results - Bismuth
Three main bismuth bearing species identified
• Wittichenite (Cu3BiS3)
• Aikenite (PbCuBiS3)
• Bornite (Cu5FeS4)
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Bornite Texture
• Solid solution bismuth is present in all bornitesmeasured
•25% of samples showed a mottled texture - two bornite phases each with different levels of bismuth
500µm
Bornite 2Bornite 1
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Mineral Compositions - Bornite
Mineral Wt% Bismuth Number of Analyses
Bright Phase in Mottled Bornite 6.54 37
Dark Phase in Mottled Bornite 0.80 220
Normal Bornite 0.61 189
Bornite (wt% by EPMA)
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Bismuth Deportment
40.5%
8.3%0.8%
50.3%
88.4%
9.4%2.2%
Aikenite
Low Bismuth Bornite
High Bismuth Bornite
Wittichenite
Mottled Bornite Samples Normal Bornite Samples
18
Rejection Strategy - Bismuth
• Probability of rejecting bismuth is low
• association with bornite
• fine grained wittichenite that occurs as disseminations in bornite
• Mottled bornite is a risk to even higher levels of contamination
• Locations of samples plotted to understand distribution
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Arsenic Mineralogy
• Arsenic mineralogy consists of Enargite and Tennantite
• As was not found in solid solution within any other sulphide minerals
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Arsenic Mineralogy
3.5 mm
Quartz
Bornite
Chalcopyrite
Calcite
Enargite/Tennantite Diopside
Garnet
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Rejection Strategy – Arsenic
• Possibility of rejecting arsenic is good
• Coarse veins (majority of enargite/tennantite) will result in liberated particles
• Thin rims on chalcopyrite or bornite (less common texture) will be more difficult to reject
22
Conclusions – Antamina Case Study
Bismuth minerology indicates probability of rejecting bismuth from Cu concentrate is low
Mottled bornite presents a risk to saleability of the Cu Concentrate
Arsenic mineralogy indicates rejection is possible based on textures in ore
Management of Issue at Antamina:• Lab and Plant piloting show that rejection of As is possible
• Blending of high Bi and As ores with other Cu/Zn ores or concentrates to reduce impact on Cu concentrates
• Negotiation of favourable commercial terms
CASE STUDY 2:
NICKEL RIM SOUTH
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Location
Mill
Smelter
60 km
Nickel Rim
South
25
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
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Objective
• Flowsheet Design
• New concentrator
• Strathcona Mill
• Strathcona Mill retrofit
• Testwork developed over several years as exploration program progressed
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Methodology
• Define and characterise geometallurgicalunits
• Quantitative mineralogy
• High confidence flotation
• Mini Pilot Plant campaigns
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Geometallurgical Units
Upper Footwall Mineralization
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Comparison of Geomet Textures
Main Zone Footwall Fringe Zone
Pentlandite
Chalcopyrite
Bornite
Plagioclase
Epidote
Cpy average size: 348µm Cpy average size: 122µm
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Flotation Testing of Geomet Units
Lime
PIBX
Charge
Pri. Rougher Sec. Rougher Scavs
Tailings
Conc 1 Conc 2 & 3 Conc 4 - 6
H2SO4, CuSO4, PIBX, DF250PIBX
Lime
PIBX, DF250
Rod Mill
Lime
PIBX
Charge
Pri. Rougher Sec. Rougher Scavs
Tailings
Conc 1 Conc 2 & 3 Conc 4 -6
H2SO4, CuSO4, PIBX,
DF250PIBX
Lime
PIBX, DF250
Rod Mill
Lime
PIBX
Charge
Pri. Rougher Sec. Rougher Scavs
Tailings
Conc 1 Conc 2 & 3 Conc 4 - 6
H2SO4, CuSO4, PIBX, DF250PIBX
Lime
PIBX, DF250
Rod Mill
Lime
PIBX
Charge
Pri. Rougher Sec. Rougher Scavs
Tailings
Conc 1 Conc 2 & 3 Conc 4 -6
H2SO4, CuSO4, PIBX,
DF250PIBX
Lime
PIBX, DF250
Rod Mill
Lime
PIBX
Charge
Pri. Rougher Sec. Rougher Scavs
Tailings
Conc 1 Conc 2 & 3 Conc 4 - 6
H2SO4, CuSO4, PIBX, DF250PIBX
Lime
PIBX, DF250
Rod Mill
Lime
PIBX
Charge
Pri. Rougher Sec. Rougher Scavs
Tailings
Conc 1 Conc 2 & 3 Conc 4 -6
H2SO4, CuSO4, PIBX,
DF250PIBX
Lime
PIBX, DF250
Rod Mill
Lime
PIBX
Charge
Pri. Rougher Sec. Rougher Scavs
Tailings
Conc 1 Conc 2 & 3 Conc 4 - 6
H2SO4, CuSO4, PIBX, DF250PIBX
Lime
PIBX, DF250
Rod Mill
Lime
PIBX
Charge
Pri. Rougher Sec. Rougher Scavs
Tailings
Conc 1 Conc 2 & 3 Conc 4 -6
H2SO4, CuSO4, PIBX,
DF250PIBX
Lime
PIBX, DF250
Rod Mill
31
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
32
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
33
New Concentrator Concept
Flash
Rougher
155µm
to
283µm 53µm
to
155µm 38µm
Regrind
34
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
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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
37
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 program assisted by quantitative mineralogy was completed 2 years prior to commercial mine production
38
Conclusions
Quantitative mineralogy has been used sucessfully to aid in process diagnosis and optimisation of concentrator flowsheets.
The work is predicated upon:• Integration of geological information into design of program
• Representative sampling• High confidence flotation• Mini pilot plant testing• High quality mineralogical data
This approach produces reliable results and enhances the diagositic power of the data and strengthens predictive capabilities for each process
39
XPS Groups
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 bymatching 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…”
