Presentation on theme: "Council for Mineral Technology General Manager: Technology"— Presentation transcript:
1 Council for Mineral Technology General Manager: Technology Developments in the hydrometallurgical processing of base metals and uranium24 February 2009Dr. Roger PaulGeneral Manager: Technology
2 IntroductionCrude forms of hydrometallurgy were practised hundreds of years agoLower grade and more complex ores, e.g. Ni lateritesMetal recoveries are of increasing importance to be cost effectiveMetal purities more stringent for modern applicationsTechnological advances, e.g. pressure leachingMajor developments in materials of constructionEnvironmental and energy issues around smelting technologies
3 Outline Cu: recovery from sulphides, low grade ores Ni: recovery from sulphides and lateritesCo: recent developments in AfricaUranium: higher price initiated numerous projectsConclusions
4 Escondida Sulphide Leach: Chile Bioleaching (mesophiles)Low-grade, run-of-mine (ROM) ore with SX / EWDesigned to produce tpa copper cathodeProject cost: US $ 870m (includes desalination plant at Coloso)Production at plant began in 2007Photograph: Becerra, E., Olea, A., Smithson, P. and Castillo, D., Engineering a Bioleaching Hydrometallurgy Plant To Achieve Maximum Microbial Activity, Viña del Mar, Chile, 2007.
5 Mintek: NICICO’s Sarcheshmeh Mine, Iran Bioleaching (mesophiles / thermophiles)Pilot heaps (6 m height, t)Ore: 100% passing 25 mm, transitional (53% of Cu(T) as CuFeS2)Maximum temperatures: up to 55°CCu dissolution: 60% ( days)Photograph: Van Staden, P. J., MINTEK.
6 Other Pacific Ore’s BioHeapTM process Geobiotics’s GEOLEACHTM process Completed a t pilot heap facility, inner MongoliaMicrobial assisted leaching of low-grade, copper mineral sulphide (whole) oresGeobiotics’s GEOLEACHTM processLow-grade, copper mineral sulphide (whole) oreMesophiles, moderate and extreme thermophilesPlanning demonstration heap at Quebrada Blanca Mine, Chile
7 Outotec’s HydroCopper® SolutionPurificationReductionChlor-AlkaliElectrolysisMelting &CastingCu conc.LeachLeach residueCu(I) oxideCu metalCu productChlorineHydrogenBrineCausticAgAuFlowsheet (Karonen, J., HydroCopper® - From Concentrate to Copper Product, Outotec Research Oy, 2008).HydroCopper® Process Block Diagram
8 Outotec’s HydroCopper® Atmospheric LeachingConcentrate (CuFeS2) leaching in acidic, chloride medium: use of chlorine / oxygenChloride stabilizes Cu(I) which is precipitated as CuO before meltingProduce high-quality copper powder (LME A Cu cathode equivalent), which can be melted and cast in required formProcess produces no sulphuric acidCan 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 recoveredClosed water circulation & efficient handling of process off-gasResidues (leach): S0, hematite or goethite
9 Outotec’s HydroCopper® Presently, engineering a commercial plant for Mongolian Erdenet Mining Corporation (Mongolia) to produce tpa copper wire rodAnother plant to be build ( tpa) for Zangezur Copper – Molybdenum Combine AG’s mine in Karajan, ArmeniaPhotograph: HydroCopperTM – Ground-Breaking Technology, Outokumpu, Internet.Demonstration Plant in Pori, Finland
10 GalvanoxTM L / S Neutralization Leach Autoclave SX / EW Cu concentrate + PyriteTailingsCathodeMiller, K. J., Sylwestrzak, L. A. and Baxter, K. G., Treatment of Copper Sulphide Deposits – Evaluation of a Galvanox™ Versus Sepon Circuit Configuration, Alta 2008 Copper Conference, June 2008.
11 GalvanoxTMAtmospheric LeachingPrimary copper sulphide (CuFeS2) concentrates leached in acidic, iron sulphate mediumEnhanced dissolution kinetics achieved by means of pyrite (FeS2) as catalystCopper recoveries of 98% in 4 h residence time; more typically, 20 h, 80°C (depending on extent of FeS2 recycle)S0 formationCompatible with SX / EWUsed in combination with high-pressure autoclave for acid, heat and Fe(III) generationEnhanced enargite (Cu3AsS4) dissolution kinetics also achieved with FeS2 as catalystArsenic converted into environmentally stable scorodite
12 Sepon Process Flow Diagram Cu concentrateFlotationNeutralizationL / SLeachSX / EWTailingsCathodeAutoclaveAcid & Fe(III)SolidsMiller, K. J., Sylwestrzak, L. A. and Baxter, K. G., Treatment of Copper Sulphide Deposits – Evaluation of a Galvanox™ Versus Sepon Circuit Configuration, Alta 2008 Copper Conference, June 2008.
13 Sepon Atmospheric / Pressure Leaching Secondary Cu-sulphide concentrates leached in acidic, iron sulphateUsed in combination with high-pressure autoclave for acid, heat and Fe(III) generationCommercialized successfully: Sepon Plant, LaosCould be modified for primary copper sulphides (CuFeS2)Main difference with respect to GalvanoxTM process:GalvanoxTM: CuFeS2 treated in atmospheric leachEquipment size, capital and operating costs not linked to primary copper sulphide content of feedSepon: CuFeS2 treated in high-pressure autoclaveEquipment size, capital and operating costs directly linked to primary copper sulphide content of feedArsenic bearing concentrates: conversion into environmentally stable scorodite
15 CESL Process Flowsheet A typical CESL copper / precious metals process flowsheet; solution to nickel and gold / silver recovery not related to Vale’s 10K plant (The CESL Process: An Environmentally Superior Alternative to Smelting, Teckcominco Brochure, Internet).
16 Teck Cominco’s CESL Process Pressure LeachingCan treat nearly all copper concentrates (incl. CuFeS2) (both high and low grades)High metal recoveries of 96% to 97% to LME Grade A CopperReagents recycledElemental sulphur (85% to 95%) and hematiteLow Capex and OpexEfficient / economic recovery of precious metalsHandles common impurities wellNet 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, BrazilAutoclave and evaporator at UHC, Brazil (Photograph: The CESL Process, Teckcominco presentation, Internet).
18 Morenci Flowsheet Cu conc. Slurry Super Fine Grinding Pressure LeachingFlashLet DownL / SWashNeutralizationWaterLimeTailingsHeap / Stockpile /Tank LeachingSolutionExtractionEWFeedCu cathodeWPLSSPLSLean BleedCoolantStreamsPrecious MetalsLeaching / RecoveryAg, Au(optional)Conditions:°C- 200 psi O2Flowsheet, Construction and Start-Up of the Freeport - McMoran Concentrate Leach Plant at Morenci, Arizona, Alta 2008 Copper Conference.
19 Freeport - McMoran’s Morenci Pressure LeachingBagdad (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, pyritetpa of concentrate (grade: 34% Cu)147 million pounds Cu produced per annum97% Cu recoveryCapital cost: US $ 250m (incl. concentrator refurbishment , concentrate leach facilities)Commissioning / start-up: 2007Pressure leach vessel systems, L/S, DEW, silica removal, construction materials working well to date
22 Tati Nickel Approaches Ultra-fine milling – lower temp leachS° reports to leach residueNi SX using versatic + Mintek synergistThe V10/Nicksyn™ system was more robust, and the circuit operation was simpler; risk associated with gypsum minimisedHigher 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 neutralisationLime boil employing vibrating mill to limit impact of gypsum scaling
23 Laterite MineralsLimonite, asbolite: (1-1.7% Ni, % Co) – suitable for PAL and Caron processNontronite: (1-5% Ni, 0.05% Co) – suitable for PAL and smeltingSerpentine: (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)Bacon, 2004
24 Laterite: Simple Process Routes Malachite Consulting
26 Laterite: Cost Comparison (Rusina) Cost Comparison as presented by Rusina
27 Goro Process Selection Pyromet route: drying (ore 50% mositure); selective reduction/smelting: high CAPEX and energy; poorer Ni and Co recoveriesRelatively 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 recoveriesNi and Co products: sulphide ppt considered; direct SX more cost-effectiveFe3+ and Cu2+ to be removed efficiently prior to SX – cause oxidation of reagent (regeneration of reagent part of flowsheet)Bacon, 2004
29 Extraction curves for 15 vol.% Cyanex 301 No Ca, Mg and Mn extractionNo neutralisation required for Ni, Co extractionSensitive to Cu and Fe in PLSStripping with HCl
30 Goro: innovative approaches Cu removal by IX to ensure very low levelCyanex 301: no extraction of Mn, Mg, CaNo 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 mediumIX for Zn removal to low levelsShould currently be commissioning
31 Ravensthorpe: Atmospheric and HPAL Shipped to Yabulufor refining
36 Co production – Projects in DRC, Zambia Co market increased from 35 to 60 ktpa due to demandPrice increased from US$20 to US$50Mintek evaluated many different flowsheets for numerous clientsVarious products targetted: metal, hydroxides (low and high grade), carbonates, oxideProcess options:Classical precipitation using lime/limestone, MgO, Na2CO3Solvent extractionPrice sensitive to the type of product and the Co:impurity levelsTransport costs of reagents and products high: products aimed at as high as possible Co content
37 Oxidative Precipitation using Air/SO2 Oxidative precipitation of Fe and Mn using air/SO2 received much attention from various institutesVery attractive process option, as SO2 generally available on site from either roaster or S-burnerFe 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 minimisedNo commercial plant yet, Ruashi being commissionedTest work indicated that gas mixing, sparging and agitation criticalEnergy 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 H2SO4 as strip liquor, unless flowrate similar to PLS flowrate so that gypsum maintained below solubility levelStrong extraction of Fe3+ requires stripping with HClCo SX using Cyanex 272 for Zn removal, and for Co recovery and separation from NiMore than one type of SX reagent in one circuit a major concern – this can be designed to prevent contamination, but there is a riskNeutralisation required during purification and recovery of CoContamination of effluent streams with dilute Na2SO4 is an environmental issueFuture of SX for Co:need to be able to produce a concentrated stream that will make crystallization viable, orneutralization by means of ammonia that could be recycled (lime boil an problematic operation)
39 Classical Precipitation Precipitation with lime/limestone:Readily available, relatively cheapLow grade Co (15-17% Co in dried solids)Mass/volume of cake cause complications when in loop with EWTransport costs/ton Co very highPrecipitation with Na2CO3:Environmental issue – produce dilute Na2SO4Produce 40-50% Co productCan be calcined for further upgrading of productPrecipitation with MgO:Produced high grade Co product (40%)Mg can be precipitated from barren stream prior to dumpingVery expensive reagentEfficient use requires careful design considerationsImpact 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 CdZn 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 costlyCd removal by IBC’s Molecular Recognition product (10 mg/kg in Grade A metal)Ionex or Septor CCIX systems considered where resin cost highIon exchange systems efficient to consistently achieve the required levels
41 Uranium Revival after decades of inactivity! Previous technologies still valid for todaySome new developments could make projects economically more viable, eg. direct SX using BPCs and RIP
42 Bateman Pulsed Columns (BPC) Mixer/SettlersBPCExtractionStagedContinuousEfficiencyLower for cost-effective # of stagesHighEntrainmentPoorerImprovedMoving partsLowMaintenanceFootprintLargeSmallSolvent vapour lossHigherLowerSafetyHigher fire hazardMuch lower
43 BPC vs MS – Stage Performance Improved efficiency with marginal increase of capital costFeed (PLS) concentrationEquilibrium line - IsothermNTU ~ 2Operating Line O : A <1NTU ~ 4Orgg/lOperating line O : A = 1Raff ConcentrationAqueous g/lBateman
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 2m3 Metrix plantSuitable for recovery and upgrading of uranium from pulps, especially where solid/liquid separation costlyKayelekera, Paladin Resources, Malawi currently commissioning RIP application
48 Hydromet ChallengesCu: chalcopyrite, especially ambient conditions, remains difficult especially for low grade oresNi: laterites – a number of laterite projects to date have failed or performed poorly, so it remains a challenge to get it rightWater 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 limitedAll S used as H2SO4 needs to be neutralized and dumped