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

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

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: % olivine + pyroxene
Dunite: >90% olivine
ophiolite, komatiite; layered intrusives (all ± serpentinized)

4. NICKEL SUPPLY: LATERITES AND SULPHIDES

5. 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
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6. EAST PINARES
Cuba
Oxide
Photo: Mick Elias

7. Oxide; some hydrous silicate
GORO
New Caledonia
Oxide; some hydrous silicate
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8. CAWSE
Western Australia
Oxide
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9. 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
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10. PRINCIPAL NICKEL MINERALS
OXIDE DEPOSITS
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11. PLATEAU
New Caledonia
Hydrous silicate; minor oxide
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12. PLATEAU
New Caledonia
Hydrous silicate
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13. CIRCE
New Caledonia
Hydrous silicate “garnierite” ore
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14. HYDROUS SILICATE (GARNIERITE) – OXIDE PROFILE

15. PRINCIPAL NICKEL MINERALS
HYDROUS NI-MG SILICATES
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16. BULONG
Western Australia
Smectite silicate
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17. MURRIN MURRIN
Western Australia
Smectite silicate
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18. MURRIN MURRIN Smectite silicate Western Australia
magnesite
Photo: Martin Wells

19. SMECTITE SILICATE PROFILE
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20. PRINCIPAL NICKEL MINERALS
SMECTITE DEPOSITS
Minor goethite, asbolan
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21. 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
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22. PROCESSING OPTIONS RELATIVE TO DEPOSIT TYPE
Oxide
(or smectite)
Transition
Hydrous silicate
Could process smectites by smelting but too costly
(after Elias 2001)

23. NICKEL LATERITE PROCESSING
Hydrous silicate ore
(“garnierite”; serpentine)
Too costly for smectite
e.g., tumbling of boulder ore
>1600ºC; high energy cost
SiO2/MgO <2 or >2.5
= ferronickel
SiO2/MgO
= 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: %
Fe: %
MgO: 25%
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24. 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: %
Co: %
Fe: %
MgO: <12.0%
Co:
90% recovery
Calcining
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25. 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
ºC; lower energy cost
cf Caron process
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26. Murrin Murrin

27. 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); ºC
Sechol/Jaguar tested HCl/MgCl2 leach at ºC. Process could also yield MgO and magnetite concentrate as products. Trial discontinued
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28. 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 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
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29. 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 *

30. 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
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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
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32. 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
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