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Council for Mineral Technology Developments in the hydrometallurgical processing of base metals and uranium 24 February 2009 Dr. Roger Paul General Manager:

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Presentation on theme: "Council for Mineral Technology Developments in the hydrometallurgical processing of base metals and uranium 24 February 2009 Dr. Roger Paul General Manager:"— Presentation transcript:

1 Council for Mineral Technology Developments in the hydrometallurgical processing of base metals and uranium 24 February 2009 Dr. Roger Paul General Manager: Technology

2 Introduction  Crude forms of hydrometallurgy were practised hundreds of years ago  Lower grade and more complex ores, e.g. Ni laterites  Metal recoveries are of increasing importance to be cost effective  Metal purities more stringent for modern applications  Technological advances, e.g. pressure leaching  Major developments in materials of construction  Environmental and energy issues around smelting technologies

3 Outline  Cu: recovery from sulphides, low grade ores  Ni: recovery from sulphides and laterites  Co: recent developments in Africa  Uranium: higher price initiated numerous projects  Conclusions

4 Escondida Sulphide Leach: Chile Bioleaching (mesophiles)  Low-grade, run-of-mine (ROM) ore with SX / EW  Designed to produce tpa copper cathode  Project cost: US $ 870m (includes desalination plant at Coloso)  Production at plant began in 2007

5 Bioleaching (mesophiles / thermophiles)  Pilot heaps (6 m height, t)  Ore: 100% passing 25 mm, transitional (53% of Cu(T) as CuFeS 2 )  Maximum temperatures: up to 55°C  Cu dissolution: 60% ( days) Mintek: NICICO’s Sarcheshmeh Mine, Iran

6  Pacific Ore’s BioHeap TM process  Completed a t pilot heap facility, inner Mongolia  Microbial assisted leaching of low-grade, copper mineral sulphide (whole) ores  Geobiotics’s GEOLEACH TM process  Low-grade, copper mineral sulphide (whole) ore  Mesophiles, moderate and extreme thermophiles  Planning demonstration heap at Quebrada Blanca Mine, Chile Other

7 Outotec’s HydroCopper ® HydroCopper ® Process Block Diagram Solution Purification Reduction Chlor-Alkali Electrolysis Melting & Casting Cu conc. Leach Leach residue Cu(I) oxide Cu metal Cu product Chlorine Hydrogen Brine Caustic Ag Au

8 Outotec’s HydroCopper ® Atmospheric Leaching  Concentrate (CuFeS 2 ) leaching in acidic, chloride medium: use of chlorine / oxygen  Chloride stabilizes Cu(I) which is precipitated as CuO before melting  Produce high-quality copper powder (LME A Cu cathode equivalent), which can be melted and cast in required form  Process produces no sulphuric acid  Can treat variety of copper concentrates (incl. lower grades)  Reduced capital and operating costs with process plant near concentrator (transportation / storage needs eliminated)  Reagents regenerated (chlor-alkali electrolysis step)  Gold and silver recovered  Closed water circulation & efficient handling of process off-gas  Residues (leach): S 0, hematite or goethite

9 Outotec’s HydroCopper ®  Presently, engineering a commercial plant for Mongolian Erdenet Mining Corporation (Mongolia) to produce tpa copper wire rod  Another plant to be build ( tpa) for Zangezur Copper – Molybdenum Combine AG’s mine in Karajan, Armenia Demonstration Plant in Pori, Finland

10 Galvanox TM L / S Neutralization Leach Autoclave SX / EW Cu concentrate + Pyrite Tailings Cathode

11 Atmospheric Leaching  Primary copper sulphide (CuFeS 2 ) concentrates leached in acidic, iron sulphate medium  Enhanced dissolution kinetics achieved by means of pyrite (FeS 2 ) as catalyst  Copper recoveries of 98% in 4 h residence time; more typically, 20 h, 80 ° C (depending on extent of FeS 2 recycle)  S 0 formation  Compatible with SX / EW  Used in combination with high-pressure autoclave for acid, heat and Fe(III) generation  Enhanced enargite (Cu 3 AsS 4 ) dissolution kinetics also achieved with FeS 2 as catalyst  Arsenic converted into environmentally stable scorodite Galvanox TM

12 Sepon Process Flow Diagram Cu concentrate Flotation Neutralization L / S Leach SX / EW Tailings Cathode Autoclave Acid & Fe(III) Solids

13 Atmospheric / Pressure Leaching  Secondary Cu-sulphide concentrates leached in acidic, iron sulphate  Used in combination with high-pressure autoclave for acid, heat and Fe(III) generation  Commercialized successfully: Sepon Plant, Laos  Could be modified for primary copper sulphides (CuFeS 2 )  Main difference with respect to Galvanox TM process:  Galvanox TM : CuFeS 2 treated in atmospheric leach Equipment size, capital and operating costs not linked to primary copper sulphide content of feed  Sepon: CuFeS 2 treated in high-pressure autoclave Equipment size, capital and operating costs directly linked to primary copper sulphide content of feed  Arsenic bearing concentrates: conversion into environmentally stable scorodite Sepon

14 Sepon Copper Project, Laos

15 CESL Process Flowsheet

16 Teck Cominco’s CESL Process Pressure Leaching  Can treat nearly all copper concentrates (incl. CuFeS 2 ) (both high and low grades)  High metal recoveries of 96% to 97% to LME Grade A Copper  Reagents recycled  Elemental sulphur (85% to 95%) and hematite  Low Capex and Opex  Efficient / economic recovery of precious metals  Handles common impurities well  Net user of water (no effluent)  Moderate energy consumption (3200 kWh / t Cu incl. oxygen plant)  Construction of Usina Hidrometalúrgica Carajás (UHC) prototype plant recently completed ( tpa Cu cathode). Near Carajás, Brazil where Vale operates Sossego copper mine

17 UHC Project, Brazil

18 Morenci Flowsheet Cu conc. Slurry Super Fine Grinding Pressure Leaching Flash Let Down L / S Wash Neutralization Water Lime Tailings Heap / Stockpile / Tank Leaching Solution Extraction EW Feed Cu cathode WPLS SPLS Lean Bleed Coolant Streams Precious Metals Leaching / Recovery Ag, Au (optional) Conditions: °C psi O 2

19 Freeport - McMoran’s Morenci Pressure Leaching  Bagdad (Phelps Dodge) demonstration plant: medium temperature pressure leaching of copper concentrate with direct electrowinning (DEW) (commercial demonstration, 2005)  Morenci Western Copper concentrate: mixed chalcopyrite, covellite, chalcocite, pyrite  tpa of concentrate (grade: 34% Cu)  147 million pounds Cu produced per annum  97% Cu recovery  Capital cost: US $ 250m (incl. concentrator refurbishment, concentrate leach facilities)  Commissioning / start-up: 2007  Pressure leach vessel systems, L/S, DEW, silica removal, construction materials working well to date

20 Bacon, 2004 World Nickel Resources

21 Tati Nickel Flow Diagram  Treating lower grade Ni-sulphide concentrate

22 Tati Nickel Approaches  Ultra-fine milling – lower temp leach  S° reports to leach residue  Ni SX using versatic + Mintek synergist  The V10/Nicksyn™ system was more robust, and the circuit operation was simpler; risk associated with gypsum minimised  Higher recoveries of >99.8% were achieved with minimal or no calcium co-extraction.  The V10/Nicksyn™ system was operated with one less extraction stage, yielding higher recoveries. Potentially, two less extraction stages could be used.  Ammonia for neutralisation  Lime boil employing vibrating mill to limit impact of gypsum scaling

23 Bacon, 2004 Laterite Minerals  Limonite, asbolite: (1-1.7% Ni, % Co) – suitable for PAL and Caron process  Nontronite: (1-5% Ni, 0.05% Co) – suitable for PAL and smelting  Serpentine: (1.5-10% Ni, % Co); typical 1-2% Ni – suitable for pyromet processes (ferronickel and matte smelting)  Garnierite: (10-20% Ni, % Co); typical 2-3% Ni – suitable for pyromet processes (ferronickel and matte smelting, especially high C ferronickel)

24 Malachite Consulting Laterite: Simple Process Routes

25 Bacon, 2004

26 Laterite: Cost Comparison (Rusina) Cost Comparison as presented by Rusina

27 Bacon, 2004 Goro Process Selection  Pyromet route: drying (ore 50% mositure); selective reduction/smelting: high CAPEX and energy; poorer Ni and Co recoveries  Relatively low saprolite:limonite ratio and relatively low Mg-content of saprolite: hydromet HPAL route selected:  HPAL: lower CAPEX and OPEX (energy consumption lower – no drying required)  Higher Ni and Co recoveries  Ni and Co products: sulphide ppt considered; direct SX more cost-effective  Fe 3+ and Cu 2+ to be removed efficiently prior to SX – cause oxidation of reagent (regeneration of reagent part of flowsheet)

28 Goro Process Flowsheet

29 CYANEX 301 Extraction curves for 15 vol.% Cyanex 301  No Ca, Mg and Mn extraction  No neutralisation required for Ni, Co extraction  Sensitive to Cu and Fe in PLS  Stripping with HCl

30 Goro: innovative approaches  Cu removal by IX to ensure very low level  Cyanex 301: no extraction of Mn, Mg, Ca  No neutralisation required for Ni, Co extraction (for limited concentration of Ni)  Regeneration of oxidised Cyanex 301 on site (oxidation limited with use of BPCs)  Switching of sulphate to chloride medium  IX for Zn removal to low levels  Should currently be commissioning

31 Ravensthorpe: Atmospheric and HPAL Shipped to Yabulu for refining

32 Laterites: Heap Leach Developments  Existing operations: Murrin Murrin (Minara Resources)  Committed projects: Caldag (European Nickel)  Projects in development:  Vale Inco  Metallica (Queensland)  GME Resources (WA)  Rusina (Phillipines)  Nickelore (WA)  RMS (PNG)  Concerns: stability of heap and associated percolation efficiency

33 Costs: Various Process Options  Why considering heap leaching when it is expected that it might be a challenge?

34 Caldag: European Nickel  Heap leaching: Caldag laterite contains low clay content  3 leach phases: neutralisation (Mg leaching) (35 kg/t H 2 SO 4 ), primary (116 kg/t H 2 SO 4 ) and secondary leaching (377 kg/t H 2 SO 4 )  Primary leach intermediate product 33% Ni, 1.5% Co  Secondary leach intermediate product 25% Ni, <1% Co, 7% Mn

35 Caldag: European Nickel

36 Co production – Projects in DRC, Zambia  Co market increased from 35 to 60 ktpa due to demand  Price increased from US$20 to US$50  Mintek evaluated many different flowsheets for numerous clients  Various products targetted: metal, hydroxides (low and high grade), carbonates, oxide  Process options:  Classical precipitation using lime/limestone, MgO, Na 2 CO 3  Solvent extraction  Price sensitive to the type of product and the Co:impurity levels  Transport costs of reagents and products high: products aimed at as high as possible Co content

37 Oxidative Precipitation using Air/SO 2  Oxidative precipitation of Fe and Mn using air/SO 2 received much attention from various institutes  Very attractive process option, as SO 2 generally available on site from either roaster or S-burner  Fe can be oxidised quantitatively at relatively low pH values (2-2.8) within a reasonably short period (2 g/L within 1 hour)  Mn oxidation done at somewhat higher pH values (3-3.5)  Co losses to be minimised  No commercial plant yet, Ruashi being commissioned  Test work indicated that gas mixing, sparging and agitation critical  Energy demand for agitation to be optimised

38 Solvent Extraction  Purification of Co stream: DEHPA for Zn, Mn, Ca  Ca extraction will result in gypsum precipitation in strip circuit when using H 2 SO 4 as strip liquor, unless flowrate similar to PLS flowrate so that gypsum maintained below solubility level  Strong extraction of Fe3+  requires stripping with HCl  Co SX using Cyanex 272 for Zn removal, and for Co recovery and separation from Ni  More than one type of SX reagent in one circuit a major concern – this can be designed to prevent contamination, but there is a risk  Neutralisation required during purification and recovery of Co  Contamination of effluent streams with dilute Na 2 SO 4 is an environmental issue  Future of SX for Co:  need to be able to produce a concentrated stream that will make crystallization viable, or  neutralization by means of ammonia that could be recycled (lime boil an problematic operation)

39 Classical Precipitation  Precipitation with lime/limestone:  Readily available, relatively cheap  Low grade Co (15-17% Co in dried solids)  Mass/volume of cake cause complications when in loop with EW  Transport costs/ton Co very high  Precipitation with Na 2 CO 3 :  Environmental issue – produce dilute Na 2 SO 4  Produce 40-50% Co product  Can be calcined for further upgrading of product  Precipitation with MgO:  Produced high grade Co product (40%)  Mg can be precipitated from barren stream prior to dumping  Very expensive reagent  Efficient use requires careful design considerations  Impact on EW bleed can be large if reagent addition un-optimal

40 Ion Exchange: Co purification  Purification of Co stream: Zn, Cu, Ni, and more recently Cd  Zn and Cu can be removed from the Co PLS stream, or advance electrolytes to the required levels (30 mg/kg in Grade A metal)  Ni removal – Dowex M4195 resin most effective option, but very costly  Cd removal by IBC’s Molecular Recognition product (10 mg/kg in Grade A metal)  Ionex or Septor CCIX systems considered where resin cost high  Ion exchange systems efficient to consistently achieve the required levels

41 Uranium  Revival after decades of inactivity!  Previous technologies still valid for today  Some new developments could make projects economically more viable, eg. direct SX using BPCs and RIP

42 Bateman Pulsed Columns (BPC) Mixer/SettlersBPC ExtractionStagedContinuous EfficiencyLower for cost-effective # of stages High EntrainmentPoorerImproved Moving partsHighLow MaintenanceHighLow FootprintLargeSmall Solvent vapour lossHigherLower SafetyHigher fire hazardMuch lower

43 BPC vs MS – Stage Performance Org g/l Aqueous g/l Operating line O : A = 1 NTU ~ 4 Operating Line O : A <1NTU ~ 2 Equilibrium line - Isotherm Feed (PLS) concentration Raff Concentration Improved efficiency with marginal increase of capital cost Bateman

44 Olympic Dam – recovery of Uranium by BPcs

45 Uranium One: BPCs Klerksdorp

46 RIP - Metrix  Mintek developed RIP for Au, base metals and uranium  Currently testing 3 resins for their metallurgical performance in laboratory as well as durability in 2m 3 Metrix plant  Suitable for recovery and upgrading of uranium from pulps, especially where solid/liquid separation costly  Kayelekera, Paladin Resources, Malawi currently commissioning RIP application

47 Metrix Demonstration Plant

48 Hydromet Challenges  Cu: chalcopyrite, especially ambient conditions, remains difficult especially for low grade ores  Ni: laterites – a number of laterite projects to date have failed or performed poorly, so it remains a challenge to get it right  Water availability and quality (now desalination plants part of CAPEX/OPEX of new plants)  S and acid balance in world: often not used where produced, transport costs high; storage facilities limited  All S used as H 2 SO 4 needs to be neutralized and dumped

49 Thank you

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