Description of the process flow for copper extraction

1. Flowsheet development in the
context of copper extraction
Sargon Lovkis

2. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
Average percentage distribution of the
accompanying elements in copper smelting.
Element Matte Slag Flue dust
Silver and gold 99 1 -
Arsenic 35 55 10
Antimony 30 55 15
Bismuth 10 10 80
Selenium 40 - 60
Tellurium 40 - 60
Nickel 98 2 -
Cobalt 95 5 -
Lead 30 10 60
Zinc 40 50 10
Tin 10 50 40
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3. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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 Mature technology
 Degree of oxidation
 Maximum concentration of copper
 Overpressure protection
 Scale, nuts and peas
 Cooling – dilution, flash, coils
 Flash vessel sizing 0.4 ~ 0.7 m/s
 Modeling reaction scheme – bisulphate
 Brickwork is half the cost
Pressure oxidation

4. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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 Not demonstrated on Chalcopyrite (yet) ORP control?
 Acidithiobacillus sp and others produce leachants acid, Fe3+
 Mesophiles 30 – 42°C eg Mintek/Bactech
 Moderate thermophiles 45 – 50°C
 Extreme thermophiles 65 – 85°C Alliance/BioCop
 Pyrite – galvanic interaction promote leach kinetics
 Requires cooling
 Tolerant of arsenic in 5+ state
 BioCop needs O2
 Saline water
Bio-leaching

5. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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 Development of the project flowsheets
 What should be shown and what should not be shown
 Flowsheet choices with examples
 Process modeling
 Project management issues which can affect the
flowsheets
 Outcome is a set of defensible flowsheets
 Review of flowsheeting in the context of processing a
chalcocite ore which has associated gold (which may, or may
not, be associated with the flotation concentrate)
Presentation focus

6. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Emissions from Copper Smelting (mg/Nm³)
Parameter Maximum value
Sulfur dioxide 1000
Arsenic 0.5
Cadmium 0.05
Copper 1
Lead 0.2
mercury 0.05
Particulates, smelter 20
Particulates, other sources 50

7. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Effluents from Copper Smelting (mg/L)
Parameter Maximum value
Total suspended solids 50
Arsenic 0.1
Cadmium 0.1
Copper 0.5
Iron 3.5
Lead 0.1
Mercury (total) 0.01
Zinc 1
Total metals 10

8. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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9. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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 Thickening, SX-EW
 Number of thickeners
 PLS clarification
 SX for high copper tenors, consult extractant vendors
 Cognis LIX 984N, Cytec Acorga OPT 5510
Recovery from the leach

10. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Presentation focus
 Limestone use
 Tailings
 Acid forming bacteria e.g. Thiobacillus sp.
 Arsenic

11. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Vat leaching at Mantos Blancos

12. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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A heap being irrigated

13. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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17. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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18. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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19. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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20. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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21. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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22. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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23. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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24. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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25. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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26. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Energy use in copper production
 ~100 GJ/tonne cathode copper
 20% in mining
 27% in crushing and grinding
 18% in flotation, pumping, regrinding, filtering
 15% in smelting
 3% in converting
 8% in gas cleaning
 7% in electro-refining

27. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Gold-copper
 A gold ore with a small amount of copper
 Copper competes with gold for cyanide (to form WAD)
 High cyanide dose (requiring subsequent detoxification)
 North Parkes example
 Roasting followed by leaching ?
 Recover cyanide by AVR/Cyanisorb process (Golden Cross, NZ)
 Recover copper and cyanide by SART process
 Several methods for free CN- destruction not specific to
copper (H2O2, Fe, Cl2, Inco, sunlight on the TSF)

28. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Isasmelt/Ausmelt
Fuel, Air
& oxygen
Copper
cooling
panelsFurnace
Taphole
Protective
slag coating
lance
Feed
port
Choosing a smelting
system
is a complex
decision

29. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Some components of a smelting complex
 Concentrate drying, flux handling
 Oxygen plant
 Shaft, bath or smelting reactor
 Converting or Direct to Blister
 Slag Cleaning
 Anode casting
 Electro-refining (including As fixation)
 Heat recovery and Waste Gas Clean-up (incl Hg, Se removal)
 Acid Plant

30. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Mineralogy - General
 Microscopy, MLA
 Chalcopyrite – polysulphide passivation – UF grinding,↑T, Cl-
 Chalcocite, bornite – needs O2 medium reaction, medium
dissolution
 Oxides, carbonates, chrysocolla – fast leaching, high
dissolution
 Associated gold, silver, PGM’s, molybdenum, rhenium
 Associated arsenic, antimony, bismuth, tellurium,
selenium, mercury
 Gold – leach then cyanide leach (or gravity eg Kansanshi)
 Iron Oxide Copper Gold eg Olympic Dam, Prominent Hill

31. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Mineralogy - Flotability
 Flotation is usually about copper grade (iron dilution)
 Gold may or may not be associated with sulphides
 Gold often follows pyrite
 Cyanide can be used to suppress pyrite
 Cyanide can activate undesired minerals
 Tarnishing and pre-aeration
 Collector blend (xanthates, dithiophosphates,
thionocarbamates, thiocarbamates and others)
 Recovering gold can mean lower copper grade
 Oxide copper - sulphydryl collectors, sulphidisation
 Poor flotation a driver for whole ore hydromet route

32. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Mineralogy – Refractory gold
 “The terrible trio” S, C and As
 Pyrite, Arsenopyrite
 Graphite, carbonates
 Arsenopyrite, Enargite, Realgar
 Gold can become locked in arsenates ?
roasting

33. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Mineralogy – Clays and Micas
 Not typically a problem with hard rock
 Copper can be adsorbed
 Gold can be encased in a clay crust
 Crowding, dilution, dextrin
 Clay type montmorillonite>kaolin>sericite
 Viscosity effects
 Countermeasures include sodium silicate, Na2S

34. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Chalcopyrite CuFeS2
 Difficult to leach
 Passive films of polysulphide, sulphur, basic ferric sulphate
 Molten sulphur at low temperature leach can block pores or
coat surfaces
 Fine grinding
 Chloride assist - CESL
 TPOX “the Sledgehammer of Bagdad”
 Not amenable to bioleaching – trials by Mintek at
Sarchesmeh, Iran

35. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Heap leach
 Delivery of acid to the heap can call for POX or bug-leach
 Leaching of secondary sulphides needs aeration
 HPGR micro-cracks may make for better extraction
 ~50 % of heap leach projects failed 70’s to 2000 mainly due to
poor preparation
 Need large diameter drill core to determine optimum crush
size
 Safety factors on column tests 1.5~3.0 for leach time, recovery
also less

36. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Comminution
 Energy comparison by Jankovic (Jankovic, A “Decreasing the Energy
Consumption in Mining”, Metso 2004)
 SAG + Ball Mill 24 kW-h/tonne
 Tertiary crush + Ball Mills 21 kW-h/tonne
 HPGR + Ball mills 17 kW-h/tonne
 HPGR + Ball mills + Vertimill 16 kW-h/tonne
 Need to thoroughly test for SAG mill amenablity and orebody
hardness variography
 Very large SAG mills require skilled maintenance support
 HPGR becoming established
 Option 2 should be considered for remote projects
 Differential hardness of minerals – flash flotation

37. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Investor conservatism
 I want to make copper…I’m not a technology developer
 We should be second not first
 Only one novel step at a time
 The Anaconda rule
 Visit operating plants if you can
 The spray dryer example
 Compelling reasons
 Concern about quality - need 99.999xx
 Consult Mawby (Aust Mining and Metallurgy 1993), SME
Handbook, Mular & Bhappu, Onemine and many others

38. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Each process unit must pay its way
 High level costs can be obtained by the O’Hara method e.g.
for a low-grade copper ore the process capital cost in 1992
dollars is US$ 13,700 T0.6 includes flotation, thickening and
filtration.
 Cost Estimation Handbook for the Australian Mining Industry
(new edition coming out)
 R2Mining database (Australianised CostMine)
 Victor Rudenno – The Mining Valuation Handbook
 Check out www.minecost.com spreadsheets

39. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Cautionary tales
Standish Group found (Ron Douglas, Newcrest):
 53 % of resource projects underperform
 31% are cancelled
 16% are successful
Failure reasons:
 Poor project management -
 Poor definition – know scope, responsibility matrix
 Poor planning & cost control (many overspent 150~200%)
 Personnel
 Suppliers – compliance, expediting
 Technical

40. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Clients and their terms
 Keep them informed and involve operations staff
 Reluctant to spend money on testwork
 Conservative
 Want the project to happen
 Rose spectacles
 Capital reduction
 Value engineers
 Second-hand equipment and re-locations
 BRIC gear requires homework
 The Anaconda Nickel dispute “But, you’re the engineer!”

41. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Copper price
 Copper has a PhD in economics
 Magma Copper, purchased 1993, shutdown 1996
 Much data available on copper production costs
 Low cost producers survive downturns

42. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Copper price history

43. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Testwork and Piloting
 Variography - Acid consumption example
 Hardness variography - Mt Todd
 Recovery variography
 Flowsheet interaction with mine plan
 Blending
 Safety factors on extractions
 Model before testwork or piloting (? Study before testwork)
 Compare, balance/reconcile, look for anomalies
 Example Sherritt-Gordon process

44. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Oxygen and O2 delivery
 Plant costs & Power consumption 1996
 Oxygen uptake into leach or Fe+++ regen slurry ~10 – 15%
 Aachen, Filblast/Atomaer

45. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Send the con to a smelter?
 ~20% of copper produced by SX-EW
 Smelter returns
 Treatment charge varies ~$ 60/tonne dry concentrate + US
4.5c/lb
 Metal payment for copper ~96.5% for copper – 1.5%
 Metal payment for gold ~95% for gold – 1 g/t + refining
 Metal payment for silver ~90% - 30 g/t + refining 30c/oz
 Arsenic penalty US $ 3.00 for each 0.1% above 0.2%
 Royalties 0.2% ~2% varies

46. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Arsenic penalties
 Smelters recover arsenic from ESP dust and electro-refining
solutions (by SX)
 Arsenic can be fixed as scorodite (ferri-arsenate)
 Smelters can expand arsenic handling as arsenic contents
increase

47. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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OHS risk issues
 Autoclave aversion – pressure = risk perception
 NOx leaks ( 30°C POX advantage) – Bakyrchik, NSC, seals
 NaSH or H2S aversion - alkalinity
 Cyanide aversion – eg North Parkes bird kill
 Arsenic aversion – Is scorodite fixation perfect?
 EW - Acid mist, arsine ?cementation AsH3, precipitation
 SX - Solvent fires, carcinogenicity

48. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Mass and energy balance
 Several simulators available
 Spreadsheets are a trap, circular reference hell
 Recycles
 Model output beside design criteria
 Model checklist
 Utilities
 Water balance

49. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Model checklist
 Mass, Element and Energy balance
 Does model line up with the Design Criteria & Flowsheets
 Component checks especially heats of formation, ρ
 Water temperatures
 Concentrations of salts, Ca++
 Check recoveries
 Extents reasonable, Zero extents
 Air composition
 Fetches and dummy stream traps

50. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Design checks
 PFD checklist
 Consultants, checkers, researchers
 Vendors, floc doctors
 Hazan
 Safety in Design Checklist
 Squad checks, other disciplines
 Peer reviews
 Model checklist
 Client reviews
 Risks and Opportunities
 Power of the dumb question

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Location factors
 Primary ball mill
 Rainfall exceeds evaporation – ZLD, burial mounds
 Limited process water or saline process water
 Redbank, Mt. Gunson – cementation
 Strip - CuSO4
 Paques – sulphide con
 Acid supply – skid, A/C eg Sepon
 Access to natural gas, coal or grid power
 Remote or undeveloped areas – KISS – concentrate
 Sovereign risk, tax risk

52. FLOWSHEET DEVELOPMENT IN THE CONTEXT OF COPPER EXTRACTION
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Flash cooling

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andrew.taylor@sargon.com.au
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