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NICKEL LATERITES characteristics, classification and processing options Charles Butt August 2007.

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Presentation on theme: "NICKEL LATERITES characteristics, classification and processing options Charles Butt August 2007."— Presentation transcript:

1 NICKEL LATERITES characteristics, classification and processing options Charles Butt August 2007

2 NICKEL DEPOSITS: LATERITES AND SULPHIDES

3 NICKEL LATERITE Regolith, derived from ultramafic rocks, that contains commercially exploitable reserves of nickel (and, commonly, cobalt) i.e., an economic term, implying high grades and/or tonnages of Ni-rich material ultramafic rocks, >~2500ppm Ni Peridotite:40-90% olivine + pyroxene Dunite: >90% olivine ophiolite, komatiite; layered intrusives (all ± serpentinized)

4 NICKEL SUPPLY: LATERITES AND SULPHIDES

5 A: Hydrous Mg-Ni silicate deposits (~35% of total resource) Altered serpentines, népouite, “garnierite” in saprolite High grade: global mean 1.53% Ni Moderate to high relief; savanna, tropical rainforest B: Smectite silicate deposits (~15% of total resource) Clays (e.g., nontronite) in upper saprolite and pedolith Low grade: global mean 1.21% Ni Low relief; savanna, semi-arid C: Oxide deposits (~50% of total resource) Fe and minor Mn oxides, in upper saprolite and pedolith Low grade: global mean 1.06% Ni Most environments CRMB CLASSIFICATION OF NICKEL LATERITES

6 EAST PINARES Cuba Photo: Mick Elias Oxide

7 GORO New Caledonia Oxide; some hydrous silicate CRMB

8 CAWSE Western Australia Oxide CRMB

9 CRBs Ni % Co % MgO % Fe % SiO % Duricrust Mottled and plasmic clays Ferruginous saprolite Saprolite Saprock Bedrock Mn oxides Shear Silica Mg discontinuity CAWSE Magnesite Serpentinized dunite Shear Mn oxides OXIDE NICKEL LATERITE PROFILE: CAWSE CRMB

10 PRINCIPAL NICKEL MINERALS OXIDE DEPOSITS CRMB

11 PLATEAU New Caledonia Hydrous silicate; minor oxide CRMB

12 PLATEAU New Caledonia Hydrous silicate CRMB

13 CIRCE New Caledonia Hydrous silicate “garnierite” ore CRMB

14 HYDROUS SILICATE (GARNIERITE) – OXIDE PROFILE Oxide

15 HYDROUS NI-MG SILICATES PRINCIPAL NICKEL MINERALS CRMB

16 BULONG Western Australia Smectite silicate CRMB

17 MURRIN Western Australia Smectite silicate CRMB

18 MURRIN MURRIN Smectite silicate Western Australia magnesite Photo: Martin Wells

19 SMECTITE SILICATE PROFILE CRMB

20 SMECTITE DEPOSITS Minor goethite, asbolan PRINCIPAL NICKEL MINERALS CRMB

21 PROCESSOREPRODUCTCOMMENT Smelting 1859, New Caledonia Hydrous silicateFerro-nickel matte Energy intensive; (smelting ~1600ºC) Caron process Reduction & ammoniacal leach 1944, Cuba Oxide; hydrous silicate (Mg <4%) Ni oxide; Ni briquettesEnergy intensive (reduction ~700ºC) low Co recovery High pressure acid leach (HPAL) 1959, Moa Bay, Cuba Oxide; smectite (Mg <4%) Ni briquettes; electronickel; oxide, sulphide, carbonate Less energy intensive. Plant & process problems Enhanced high pressure acid leach (EPAL) Hydrous silicateNi-Co hydroxideAtmospheric leach after HPAL Acid heap leach H 2 SO 4 Atmospheric leach H 2 SO 4 HCl/MgCl 2 Oxide; smectite hydrous silicate Ni-Co hydroxideLower capital cost; Lower recoveries CRMB PROCESSING OPTIONS FOR NICKEL LATERITES

22 Oxide (or smectite) Transition Hydrous silicate ( after Elias 2001) PROCESSING OPTIONS RELATIVE TO DEPOSIT TYPE

23 Hydrous silicate ore (“garnierite”; serpentine) Too costly for smectite e.g., tumbling of boulder ore >1600ºC; high energy cost SiO 2 /MgO 2.5 = ferronickel SiO 2 /MgO = matte ~77% of total production in % or less of new capacity NICKEL LATERITE PROCESSING Smelting FEEDFEED PROCEESSPROCEESS Drying Upgrading Reduction roast Smelting Converting PRODUCTPRODUCT Fe-Ni or Ni matte 90% recovery Ni: >2.0% Co: 0.04% Fe: 20% MgO: 25% CRMB

24 High grade oxide ore, some hydrous silicate; tolerates more Mg than HPAL. Too costly for smectite. ~700ºC; high energy cost Complex pyrometallurgical - hydrometallurgical process; high energy cost with lower recoveries than smelting and PAL. No new plants anticipated NICKEL LATERITE PROCESSING Caron process FEEDFEED PROCEESSPROCEESS Reduction roast Grinding, drying Leach ammoniacal CO 3 Cobalt separation Ni carbonate precipitation PRODUCTPRODUCT Ni: 94% recovery Ni: 1.8% Co: 0.1% Fe: 25-40% MgO: <12.0% Co: 90% recovery Calcining CRMB

25 Oxide or smectite ore, low Mg and Al to reduce acid consumption Upgrade oxide by screening to remove barren silica High capital costs, with new plants having numerous teething problems in plant and process. Product options include sulphides: Murrin 2, Halmahera hydroxide: Ravensthorpe, Vermelho carbonate: Cawse NICKEL LATERITE PROCESSING High pressure acid leaching FEEDFEED PROCEESSPROCEESS Leach H 2 SO 4 Ore preparation Acid plant S Energy Wash/neutralize SX-EW or precipitate PRODUCTPRODUCT Ni: 94% recovery Ni: 1.3% Co: 0.13% MgO: <5.0% Co: 90% recovery ºC; lower energy cost cf Caron process CRMB

26 Murrin

27 NICKEL LATERITE PROCESSING Atmospheric leaching FEEDFEED Oxide ore (but, potentially, any ore type, including low grade hydrous silicate) PROCEESSPROCEESS Agitate, heat and leach H 2 SO 4 Ore preparation Acid plant or excess from HPAL S Energy Wash/neutralize SX-EW or precipitate PRODUCTPRODUCT Ni (Co) hydroxide ~80-90% recovery Ravensthorpe, Gag Island: oxide, serpentine saprolite (hydrous silicate) Sechol: oxide, saprolite Enhanced high pressure acid leaching (EPAL); ºC Sechol/Jaguar tested HCl/MgCl 2 leach at ºC. Process could also yield MgO and magnetite concentrate as products. Trial discontinued CRMB

28 NICKEL LATERITE PROCESSING Heap leaching FEEDFEED Potentially, any ore type, including low grade hydrous silicate and rejects PROCEESSPROCEESS Heap, irrigate for months Ore preparation Acid plant or excess from HPAL S Energy Wash/neutralize PRODUCTPRODUCT Ni (Co) hydroxide ~80% recovery SX-EW or precipitate Caldag, Nornico - oxide; Murrin Murrin - smectite Crush; upgrade by screening to remove barren silica Neutralize using low grade saprolite ore Suitable for smaller deposits; low capex and opex CRMB

29 From top of Heap 2 looking at Çaldağ mountain Demonstration precipitation plant European Nickel plc m 20 km Çaldağ Heap Leach project, Turkey Çaldağ Izmir * Istanbul 50 km *

30 HPALAtmospheric leach Heap leach Capital expenditure $17-22$13-16$8-12 Operating expenditure $2.50 $ US/lb Ni Source: Minara Resources, 2006 PROCESSING OPTIONS FOR NICKEL LATERITES CRMB

31 NICKEL LATERITE PROCESSING: Summary and conclusions 1: Nickel laterites form ~ 75% of known Ni resources 2: By 2010, over 50% of Ni will be derived from NiL 3: Three main ore types: oxide, hydrous silicate, smectite; all products of humid weathering, ± later modification 4: “Traditional” processing (smelting, Caron) is generally very energy intensive 5: HPAL plants use less energy but require high capital expenditure and are yet to be fully optimized; best suited to large deposits CRMB

32 6: Acid leaching at lower temperatures and ambient pressures offer lower capital expenditure (but lower recovery). Suited for treating lower grade ore and small or remote deposits 7: Better mineralogical characterization is needed to optimize grade control, beneficiation and processing NICKEL LATERITE PROCESSING: Summary and conclusions (continued): CRMB


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