Process Diagnosis using Quantitative Mineralogy

Transcription

1 Process Diagnosis using Quantitative Mineralogy L. Kormos 1, J. Oliveira 1, D. Fragomeni 1, E. Whiteman 1, J. Carrión De la Cruz 2 1 Xstrata Process Support 2 Compañia Minera Antamina S.A. 42 nd Annual CMP Conference January 19-21, 2010

2 XPS Groups Sudbury, Ontario 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. Process Control - Identify and deliver robust process control technology and engineering solutions to achieve Operational Performance Excellence. 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 2

3 Process Mineralogy Mineral Processing Sampling & Statistics Process Mineralogy Mineralogy 3

4 Process Mineralogy Methodologies Representative Sampling Geometallurgical Unit Definition High Confidence Flotation Design of Experiments Mini Pilot Plant Campaigns Quantitative Mineralogy (QEMSCAN + EPMA) 4

5 Case Studies Contamination of Copper Concentrates at Antamina Flowsheet Development at Nickel Rim South 5

6 CASE STUDY 1: ANTAMINA BORNITE ZONE

7 Antamina Mine Location YANACOCHA PIERINA ANTAMINA CERRO DE PASCO TINTAYA MARCONA CERRO VERDE CUAJONE TOQUEPALA 7

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 8

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 9

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 10

11 Schematic Lithology and Metal Zonation NW Heterolithic Breccia Cu, ± Zn Zn,Pb,Ag Ag Pb Wollastonite-Bornite Exoskarn Cu, Zn, Ag, Bi Zn, Bi SE X X X X X X X X X Zn,Pb,Ag,Bi Green Exoskarn Zn,Cu,Ag,Bi,Pb Endoskarn Cu, Mo Brown and Green Exoskarn Cu, Zn, Ag, Bi 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 Quartz Monzonite Intrusive Mo, Cu X X X X X X X X X X X X Meters Hornfels ± Zn, ± Pb, ± Ag, ± Bi Indeterminate Skarn Cu,Zn,±Mo,±Bi Marble ± Zn, ± Pb, ± Ag, ± Bi 11

12 Cu Ore Zonation (4200m bench) Bornite Ore 11% Chalcopyrite Ore 89% 12

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 13

14 Results - Bismuth Three main bismuth bearing species identified Wittichenite (Cu 3 BiS 3 ) Aikenite (PbCuBiS 3 ) Bornite (Cu 5 FeS 4 ) 14

15 Bornite Texture Solid solution bismuth is present in all bornites measured 25% of samples showed a mottled texture - two bornite phases each with different levels of bismuth 500µm Bornite 1 Bornite 2 15

16 Mineral Compositions - Bornite Bornite (wt% by EPMA) Mineral Wt% Bismuth Number of Analyses Bright Phase in Mottled Bornite Dark Phase in Mottled Bornite Normal Bornite

17 Bismuth Deportment 8.3% 0.8% 9.4% 2.2% 50.3% 40.5% Mottled Bornite Samples 88.4% Normal Bornite Samples High Bismuth Bornite Low Bismuth Bornite Aikenite Wittichenite 17

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 18

19 Arsenic Mineralogy Arsenic mineralogy consists of Enargite and Tennantite As was not found in solid solution within any other sulphide minerals 19

20 Arsenic Mineralogy 3.5 mm Chalcopyrite Bornite Enargite/Tennantite Garnet Quartz Calcite Diopside 20

21 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 21

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 22

23 CASE STUDY 2: NICKEL RIM SOUTH

24 Location Mill Nickel Rim South Smelter 60 km 24

25 Nickel Rim South Mine Discovered in % 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 25

26 Objective Flowsheet Design New concentrator Strathcona Mill Strathcona Mill retrofit Testwork developed over several years as exploration program progressed 26

27 Methodology Define and characterise geometallurgical units Quantitative mineralogy High confidence flotation Mini Pilot Plant campaigns 27

28 Geometallurgical Units Upper Footwall Mineralization 28

29 Comparison of Geomet Textures Pentlandite Chalcopyrite Bornite Plagioclase Epidote Main Zone Footwall Fringe Zone Cpy average size: 348µm Cpy average size: 122µm 29

30 Flotation Testing of Geomet Units Lime PIBX, DF250 Lime PIBX Rod Mill Charge PIBX H2SO4, CuSO4, PIBX, DF250 Pri. Rougher Sec. Sec. Rougher Scavs Tailings Conc 1 Conc 2 & 3 Conc

31 Flotation Testing of Geomet Units 35 Ni+Cu Rougher Grade vs Ni Recovery % Ni + Cu Grade % Ni Recovery Upper Footwall Main Footwall Fringe Footwall Contact Sublayer Contact Footwall Breccia Low Sulphur PGM 31

32 Impact of CMC on Sublayer Ores 100 Ni Recovery % Flotation Time, min Footwall Breccia Sublayer Breccia Sublayer Breccia w CMC 32

33 New Concentrator Concept Flash Rougher 155µm to 283µm 53µm to 155µm 38µm Regrind 33

34 Staged Grind Flowsheet Improvements over Strathcona % Recovery Improvement Fringe Low Sulphur PGM Ni Cu Pt Pd 34

35 Strathcona with Cu Pre-Float Footwall Ore Contact Ore 5 P 56 75µm P 56 75µm % Recvoery /50 25/75 0 Ni Cu Cu Pre-float Conc Pri Ro Conc Sec Ro Conc Scav Tails Scav Conc 35

36 Flowsheet Demonstration Each flowsheet option was demonstrated in the MPP Primarily from drill core samples 36

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 37

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 38

39 XPS Groups 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. Process Control - Identify and deliver robust process control technology and engineering solutions to achieve Operational Performance Excellence. 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 39