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

NICKEL DEPOSITS: LATERITES AND SULPHIDES CUBA INDONESIA AUSTRALIA LATERITES SULPHIDES NEW CALEDONIA PHILIPPINES 22oN 22oS

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)

NICKEL SUPPLY: LATERITES AND SULPHIDES

CLASSIFICATION OF NICKEL LATERITES 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

EAST PINARES Cuba Oxide Photo: Mick Elias

Oxide; some hydrous silicate GORO New Caledonia Oxide; some hydrous silicate CRMB

CAWSE Western Australia Oxide CRMB

OXIDE NICKEL LATERITE PROFILE: CAWSE CRBs021-01 Ni % 0.08 0.20 1.26 0.46 0.47 0.19 0.25 Co % 0.04 0.07 0.15 0.16 0.09 0.12 MgO % 1.0 0.3 1.1 29.4 39.5 42.3 Fe % 7.6 8.5 44.1 18.1 7.2 5.8 8.3 SiO % 2 70.8 82.3 35.9 72.3 26.7 28.3 36.6 Duricrust Mottled and plasmic clays Ferruginous saprolite Saprolite Saprock Bedrock Mn oxides Shear Silica Mg discontinuity CAWSE Magnesite Serpentinized dunite CRMB

PRINCIPAL NICKEL MINERALS OXIDE DEPOSITS CRMB

PLATEAU New Caledonia Hydrous silicate; minor oxide CRMB

PLATEAU New Caledonia Hydrous silicate CRMB

CIRCE New Caledonia Hydrous silicate “garnierite” ore CRMB

HYDROUS SILICATE (GARNIERITE) – OXIDE PROFILE

PRINCIPAL NICKEL MINERALS HYDROUS NI-MG SILICATES CRMB

BULONG Western Australia Smectite silicate CRMB

MURRIN MURRIN Western Australia Smectite silicate CRMB

MURRIN MURRIN Smectite silicate Western Australia magnesite Photo: Martin Wells

SMECTITE SILICATE PROFILE CRMB

PRINCIPAL NICKEL MINERALS SMECTITE DEPOSITS Minor goethite, asbolan CRMB

PROCESSING OPTIONS FOR NICKEL LATERITES ORE PRODUCT COMMENT Smelting 1859, New Caledonia Hydrous silicate Ferro-nickel matte Energy intensive; (smelting ~1600ºC) Caron process Reduction & ammoniacal leach 1944, Cuba Oxide; hydrous silicate (Mg <4%) Ni oxide; Ni briquettes Energy 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) Ni-Co hydroxide Atmospheric leach after HPAL Acid heap leach H2SO4 Atmospheric leach H2SO4 HCl/MgCl2 Oxide; smectite hydrous silicate Lower capital cost; Lower recoveries CRMB

PROCESSING OPTIONS RELATIVE TO DEPOSIT TYPE Oxide (or smectite) Transition Hydrous silicate Could process smectites by smelting but too costly (after Elias 2001)

NICKEL LATERITE PROCESSING Hydrous silicate ore (“garnierite”; serpentine) Too costly for smectite e.g., tumbling of boulder ore 1400 - >1600ºC; high energy cost SiO2/MgO <2 or >2.5 = ferronickel SiO2/MgO 1.8-2.2 = matte ~77% of total production in 2000 33% or less of new capacity NICKEL LATERITE PROCESSING Smelting F E D P R O C S Drying Upgrading Reduction roast Converting U T Fe-Ni or Ni matte 90% recovery Ni: >2.0% Co: 0.04% Fe: 20% MgO: 25% CRMB

NICKEL LATERITE PROCESSING 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 F E D P R O C S Reduction roast Grinding, drying Leach ammoniacal CO3 Cobalt separation Ni carbonate precipitation U T Ni: 94% recovery Ni: 1.8% Co: 0.1% Fe: 25-40% MgO: <12.0% Co: 90% recovery Calcining CRMB

High pressure acid leaching 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: Murrin2, Halmahera hydroxide: Ravensthorpe, Vermelho carbonate: Cawse NICKEL LATERITE PROCESSING High pressure acid leaching F E D P R O C S Leach H2SO4 Ore preparation Acid plant Energy Wash/neutralize SX-EW or precipitate U T Ni: 94% recovery Ni: 1.3% Co: 0.13% MgO: <5.0% Co: 90% recovery 240-270ºC; lower energy cost cf Caron process CRMB

Murrin Murrin

NICKEL LATERITE PROCESSING Atmospheric leaching F E D Oxide ore (but, potentially, any ore type, including low grade hydrous silicate) P R O C S Agitate, heat and leach H2SO4 Ore preparation Acid plant or excess from HPAL Energy Wash/neutralize SX-EW or precipitate U T Ni (Co) hydroxide ~80-90% recovery Ravensthorpe, Gag Island: oxide, serpentine saprolite (hydrous silicate) Sechol: oxide, saprolite Enhanced high pressure acid leaching (EPAL); 80-105ºC Sechol/Jaguar tested HCl/MgCl2 leach at 80-105ºC. Process could also yield MgO and magnetite concentrate as products. Trial discontinued CRMB

NICKEL LATERITE PROCESSING Heap leaching F E D Potentially, any ore type, including low grade hydrous silicate and rejects P R O C S Heap, irrigate for 12-18 months Ore preparation Acid plant or excess from HPAL Energy Wash/neutralize U T 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

Çaldağ Heap Leach project, Turkey From top of Heap 2 looking at Çaldağ mountain Demonstration precipitation plant European Nickel plc 2006 200 m 20 km Çaldağ Heap Leach project, Turkey Çaldağ Izmir * Istanbul 50 km *

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

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

NICKEL LATERITE PROCESSING: Summary and conclusions (continued): 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 CRMB