2. 1. Overview of Nickel and its deposits
2. What are nickel laterites
3. Description of a laterite profile
4. Chemical weathering of ultramafic rocks
5. Factors that influence laterite formation
6. Role of various elements during laterisation
7. Minerals associated with ultramafics and laterites
8. Physical and chemical properties of nickel laterites
relevant to their exploitation
9. Processing of Nickel Laterites
10. Exploration strategy and Management of Nickel Laterite
3.
4. Nickel was first discovered in 1751
Derived from German “kupfernickel” false copper
Major uses of nickel:
Stainless steel 65%
Specialty alloys 12%
Plating 8%
Other uses 15%
Addition of nickel imparts corrosion resistance, and ability
to withstand high temperatures and pressures
Primary nickel supply comes from newly mined ores
Secondary nickel supply comes from recycling scrap
5. Major Nickel producing companies:
1. Norilsk 243,000 t (19%)
2. CVRD Inco 221,000 t (17%)
3. BHP-Billiton 146,000 t (11%)
4. Falconbridge 114,000 t (9%) [Now Exstrata]
5. Jinchuan 93,000 t (7%)
6. Eramet 59,000 t (5%)
7. Sumitomo 51,000 t (4%)
Major Nickel producing countries:
1. Russia (Norilsk Nickel group)
2. Canada (CVRD Inco, Falconbridge, Sheritt)
3. Australia (BHP-B, Minara, Cawse, LionOre)
6. Sulphide nickel deposits
Nickel as nickel sulphide pentlandite, millerite
Nickel ores processed through milling and smelting
Laterite nickel deposits
Oxide Ni deposits: Ni as hydroxide in the ferruginous zone
Clay silicate deposits: Ni as clay silicate
Hydrous silicate deposits: Ni as hydrous-silicate in
saprolite
Nickel ores processed through pyro-metallurgy (smelting)
or hydro-metallurgy (leaching)
14. Buchanan Hamilton introduced the term for the “brick
stones” used by people in South India that hardened on
exposure to the sun (Latin word “later” means brick)
Current use of the term “laterite” does not require this
hardening characteristic
Nickel laterites are:
Residual soils
Rich in sesquioxides of iron with some nickel enrichment
Have developed over mafic/ultramafic rocks
Through processes of chemical weathering and supergene
enrichment
Under tropical climatic conditions
15. A soil is a naturally occurring body made up of
layers which differ from the parent material in
their physical, chemical, mineralogical,
biological and textural characteristics.
Soils are formed through several processes that
include:
Addition through transportation
Removal at the top of the profile through erosion
Removal from the soil profile through leaching
Migration of elements through the soil profile
(through leaching)
16. TEMPERATURE
HUMIDITY / RAINFALL
TUNDRA
Gray
Desert
and Sierozem
Brown
Chestnut
Degraded
Chernozem
Brunizem
PODZOL
Brown Podzolic
Gray-Brown Podzolic
Red Desert
Redd
ish
Bro
wn
Reddish
Chestnut Reddish
Prairie
Red-Yellow Podzolic
LATERITE
Reddish brown Latosolic
Yellowish brown Latosolic
TUNDRA
PODZOL
Red
Desert
Degraded
Chermozem
Brunizem
Brown Podzolic
Gray-Brown
Podzolic
Reddish
Prairie
Red-Yellow
Podzolic
Yellow-brown
Latsolic
Reddish-brown
Latsolic
LATERITE
Gray
Desert
&
Sierozem
Brown
Chestnut
Chemozem
Reddish
Brown
Reddish
Chestnut
Dry
Dry
Wet
Wet
Cold Cold
Hot Hot
GREAT SOIL GROUPS OF THE WORLD
17. In stratigraphy, laterites represent
unconformities (break in stratigraphic sequence)
Laterites make poor soils for agriculture
Laterites are source of metals:
Ni, Co, Cr, Fe (from laterites derived from ultramafic
rocks)
Al (from laterites derived from aluminous rocks)
21. Red Laterite
Yellow Laterite
Saprolite zone
Bedrock
Hematite zone
Limonite zone
Zone of altered bedrock
(clayey matrix + boulders)
Fresh bedrock Ferruginous
Zone
Intermediate zone
22. Red Laterite
Yellow Laterite
Saprolite zone
Bedrock
• Fresh bedrock
• Joints and fractures opening up as
hydrostatic pressure is removed
• Percolating rain water circulating along
joint and fracture surfaces
• Signs of incipient weathering
• Original rock composition and texture
fully preserved
23.
24. Red Laterite
Yellow Laterite
Saprolite zone
Bedrock
• Rock fragments + saprolised boulders +
precipitated silica + garnierite
• Chemical weathering proceeding actively
along joints and fractures
• Silica and magnesia being leached out
• Rock porosity increasing with time
• Bulk density decreasing with time
• Zone still not collapsed
• Original rock texture still preserved
• Upper part more ferruginous than lower
part
• High SiO2 and MgO contents
• Low Fe content
• Zone of supergene Ni enrichment
25.
26.
27. Red Laterite
Yellow Laterite
Saprolite zone
Bedrock
• Soft smectite clays + silica
• Chemical weathering (silica & magnesia
leaching) extremely advanced
• Rock porosity at its maximum
• Bulk density at its lowest
• Zone is ready to collapse
• Moisture content at its highest
• Original rock texture barely discernible
• Upper part more ferruginous than lower
part
• Often the preferred location for Mn and
Co enrichment
28. Red Laterite
Yellow Laterite
Saprolite zone
Bedrock
• Zone rich in hydrated Fe oxides +
• Chemical weathering near complete
• Silica and magnesia fully leached out
• Residual concentrations of other
elements at near maximum
• Rock porosity decreasing with time
• Bulk density increasing with time
• Zone is collapsed
• Original rock texture obliterated
29. Red Laterite
Yellow Laterite
Saprolite zone
Bedrock
• Zone rich in hematite and less hydrated
Fe oxides (goethite)
• Chemical weathering complete
• Silica and magnesia fully leached out
• Residual concentrations of other
elements at maximum
• Rock porosity decreasing with time
• Bulk density increasing with time
• Zone is completely collapsed
• Original rock texture obliterated
• Further changes include formation of
duricrust (ferricrete or silcrete)
35. TERMINOLOGY
Rich in mafic (ferro-magnesian) minerals
Generally contain less than 45% SiO2 (except pyroxenite)
Colour indices of more than 70
Generally lack any feldspar
No exact counterpart among lavas (extrusive rocks)
The density of ultramafic magma is too high to rise through the sialic
portion of the crust
FORMATION
Crystal settling (by gravity) in a magma chamber (layered intrusions)
Intrusion of hot, semi-solid, crystalline mass (dykes, lenses, stocks)
Through obduction of oceanic crust upon continental landmass in
orogenic belts
36. DUNITE
Monomineralic rock composed entirely of olivine. Originally seen at Dun
Mountain in New Zealand
PYROXENITE
Monomineralic rock composed entirely of pyroxene
Orthopyroxenites: Bronzitites
Clinopyroxenites: Diopsidites; diallagites
HORNBLENDITES
Monomineralic rocks composed entirely of hornblende
SERPENTINITE
Monomineralic rock composed entirely of serpentine
PERIDOTITE
Ultramafic rocks containing olivine and other mafic minerals
Pyroxene peridotite / Hornblende peridotite / Mica peridotite
40. Ni in ultramafic rocks is primarily in mafic minerals
High in olivines (0.2 – 0.3% Ni)
Low in orthopyroxenes (0.05 – 0.1% Ni)
Very low in clinopyroxenes (< 0.05% Ni)
Thus, decrease in the olivine content of the ultramafic
reduces the overall nickel content of the rock:
Highest Ni grades in dunites
Lower Ni grades in peridotites
Lowest Ni grades in pyroxenites
Ni in mafic minerals is largely as a replacement of Mg
Ni in mafic minerals falls with the order of crystallisation
Some Ni may exist as replacement of the larger Fe atoms
Primary chromite and magnetite may contain minor Ni
41. Four major processes under which rocks change their physical or chemical
properties:
Melting (at very high temperatures)
Metamorphism (high temperatures / pressure / addition)
Hydrothermal alteration (through high-temperature fluids)
Weathering (at ordinary temperatures and pressure)
Types of weathering:
Physical (mechanical breakdown of rocks)
▪ erosion, thermal expansion/contraction, action of plants
Chemical (breakdown of rocks through chemical processes)
▪ contact with water, oxygen, carbon dioxide, etc.
43. “The process in which rocks react to atmospheric, hydrospheric and biologic agencies to
produce mineral phases that are more stable”
1. Hydrolysis
Oxygen, carbon dioxide, ground water, dissolved acids attack the minerals in
the rock
2. Oxidation
Elements released by chemical weathering are oxidised
3. Hydration
Reaction with water adds the hydroxyl ion to newly formed minerals
4. Solution
The more soluble products of weathering are dissolved and removed
And the cycle continues .....
44. RAIN AND THUNDER STORMS
Nitrous oxides, CO2
HUMOUS (Organic) LAYER
WATER TABLE
ZONE OF OXIDATION
(Reducing conditions)
(Reducing conditions)
Acidic
Rain
Acidic
Rain
45. The sum of negative and positive charges are equal
within a crystal (Pauling’s Rule)
However, exposed atoms and ions on crystal surfaces
possess unsaturated valencies and are thus charged
Water molecules are attracted to the charged surfaces
Attractive forces cause polarisation of water into H+
and OH- ions
Hydroxyl (OH)- ions then bond to exposed cations
Hydrogen ions (H)+ bond to exposed oxygen and other
negative ions
In the case of silicates, H+ attacks the Si-O-Si bonds
and releases silica as orthosilicic acid (H4SiO4)
46. Common oxidising agent in the soil is oxygen dissolved in ground water
Much of ferrous ions in the weathering profile are converted to ferric
state under highly oxidising conditions.
Oxidising conditions exist only above the water table
Below the water table, conditions are generally reducing
Organic matter at the very top may also create reducing conditions
Hot, well-drained environment favours oxidation through the
destruction of organic matter and lowering of water table
Cool, poorly-drained environment promotes accumulation of organic
matter and reducing conditions
47. In the presence of Hydroxyl ion (OH)-, freshly created oxides are converted to
hydroxides
The more common hydroxides found in lateritic soils include:
Hydrated iron oxides: Goethite / Limonite
Hydrated Aluminum oxides:Boehmite / Bauxite / Gibbsite
Hydrated manganese oxides: Pyrochroite / Manganite /
Psilomelane
Many new secondary mafic minerals are formed due to hydration:
Serpentine /Talc / Chlorite
Hydration also results in the formation of clay minerals:
Kaolinite; Halloysite; Illite; Smectites; Saponite
48. For chemical weathering to continue, broken down constituents
must be removed
Solution of broken down constituents exposes new surfaces
Dissolved constituents are removed by percolating ground waters
Ground waters generally travel from top to bottom in a
weathering profile
Dissolved constituents are eventually drained out to rivers, lakes
and the ocean
The relative proportions of dissolved constituents in ground water
confirm the relative solubilities of various oxides in the laboratory
Dissolved CO2 in ground water is a very strong leaching agent
50. Polynov’s estimate of elemental mobilities:
Hudson’s estimate of elemental mobilities
Cl > SO4 > Na > Ca > Mg > K > Si > Fe+++ > Al
Berger’s estimate of hydroxide mobilities:
Cl SO4 Ca++ Na+ Mg++ K+ SiO2 Fe2O3 Al2O3
100 57.0 3.0 2.4 1.3 1.25 0.2 0.04 0.02
Soluble Supergene Residual
Mg Mn++ Co++ Ni++ Al+++ Cr+++ Fe+++
3.1 1.3 -1.7 -3.2 -15.3 -16.4 -18.1
51. Highly soluble and highly mobile
Easily leached out of the laterite profile
Taken to lakes, rivers and the sea
Ca, Na, Mg, K, Si
Limited solubility –— Supergene enrichment
Partly soluble in acidic ground water
Insoluble in the presence of more soluble elements (Si,
Mg)
Ni++, Co++, Mn++
Non soluble and residual
Insoluble in ground waters at ordinary pH / Eh conditions
Make up bulk of the residual soil
Al+++, Fe+++, Cr+++,Ti, Mn+++
52. Forsterite: 2MgO.SiO2 (MgO = 57.3%)
Highly unstable in weathering
environment
Individual SiO4 tetrahedra are
weakly bonded by cations
Magnesia is highly soluble in ground water
Release of magnesia breaks down the Olivine structure
Breakdown of Olivines releases various cations:
Mg, Fe, Al, Ni, Mn
Sorowako Olivine:
• FeO = 9.0%
• Al2O3 = 0.4%
• NiO = 0.37%
• MnO = 0.12%
• Cr2O3 = 0.02%
• TiO2 = 0.02%
Replacements
53. Enstatite: MgO.SiO2 (MgO = 40.2%)
Relatively unstable in weathering
environment (but < Olivine)
Individual SiO4 tetrahedra are
bonded by shared Oxygen
Magnesia is highly soluble in
ground water
Release of magnesia breaks down the Pyroxene
Breakdown of Pyroxenes releases various cations:
Mg, Fe, Al, Ca, Cr, Mn, Ni
Sorowako Pyroxene:
Opx Cpx
• FeO = 6.0 2.5
• Al2O3 = 3.2 3.5
• CaO = 1.9 21.7
• NiO = 0.08 0.05
• MnO = 0.13 0.08
• Cr2O3 = 0.58 0.86
• TiO2 = 0.05 0.09
Replacements
54. Serpentine: 3MgO.2SiO2.2H2O [H4Mg3Si2O9]
Magnesia is leached out first, leaving behind a silica
enriched phase or montmorillonite and chlorite
Ni can replace the magnesium being leached.This results
in the formation of:
Nickeliferous serpentine
Through a similar process, nickel is also fixed inTalc,
Chlorite, and Smectite
Eventually, montmorillonite and chlorite also break down,
releasing remaining magnesia and silica and forming iron
sesquioxides
55. Course of Laterisation
MgO
SiO2
FeO or F2O3
Bedrock
Soft
Saprolite
Hard
Saprolite
All compositions are shown
in terms of the three oxides
PATH OF
LATERISATION
Limonite
56. Highly Mobile
Ca, Na, K, Mg
Less Mobile
Si
Non-Mobile
Fe, Al, Cr, Ti
Olivine
Opx
Cpx
Montmorillonite
Illite
Nontronite
Goethite
Siliceous
Nontronite
Ultramafic
Rocks
57. Course of Laterisation
MOBILE vs. NON-MOBILE ELEMENTS
IN COMMON MINERALS ASSOCIATED WITH LATERITES
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100
NON-MOBILE ELEMENTS (Al2O3 + Fe2O3)
MOBILE
ELEMENTS
(Na2O+K2O+CaO+MgO+SiO2)
Halloysite
Kaolin
Illite
NATURAL OLIVINES
& PYROXENES
Serpentine
CLAYS &
CHLORITE
HYDROXIDES OF Al AND Fe
Clinochlore
Montmorillonite
Hematite
Parent rock
Saprolite with clays
having low Fe & Al
Saprolite & intermediate
zone with clays having high
Fe & Al
Hydroxides of aluminium and
iron (yellow & ochre colour)
Red
laterite
Nontronite
58. Dunite Goethite
Mineral Olivine Goethite
Composition (Mg,Fe)2SiO4 Fe2O3.H2O
Block size, m. 1 x 1 x 1 1 x 1 x 0.32
Particle density 3.2 4.4
Dry Bulk Density 3.2 1.1
Fe content, % 5.5% 50%
Kg of Fe 176 176
Dunite
Goethite
Volume of Goethite =
Dunite: density x % Fe
Goethite: density x % Fe
= =
17.6
55.0
0.32
1.0 m
0.32 m
61. WEATHERING
SYSTEM
Temperature
Rainfall
Acidity of rain
Seasonality
ATMOSPHERIC BIOSPHERIC
HYDROSPHERIC LITHOSPHERIC
COMBINATION
Vegetation type
Decay intensity
Microbial activity
Human activity
Water availability
Water absorption
Up/down movement
Porosity/drainage
Water table position
Water table fluctuation
Geomorphology
Rock composition
Mineral grain size
Mineral stabilities
Porosity
Fractures & joints
pH (acidity)
Eh (Redox)
Rate of removal
Time duration
FACTORS THAT INFLUENCE CHEMICAL
WEATHERING
62. TEMPERATURE
Each 10 C change increases weathering speed by 2-3 times
Chemical weathering in tropics is 20-40 times higher than in
temperate regions
RAINFALL
Acidity of rain (dissolved CO2, Nitrous oxides)
Amount of precipitation (higher rainfall = higher leaching)
Seasonality:Constant humid vs.Wet/dry seasonal
EFFECT OF CLIMATE
Hematitic soils develop in hot and dryer climate
Goethitic/limonitic soils develop in hot and wet climate
Hot and humid climate leads to complete leaching of SiO2 & MgO
Seasonal wet/dry climate leads to formation of smectites
Climate can vary considerably over time [fossil laterites]
64. Tropical climate leads to rapid decay of biological
matter
Microbial activity hastens the decay process
Vegetation decay forms various organic acids: humic,
carbonic, fulvic, crenic, apocrenic, oxalic and lichenic
acids
Presence of organic matter creates reducing
conditions (assists the conversion of ferric to ferrous
iron)
65. WATER ABSORPTION
WATERTABLE
Vadose zone: lying above the water table.
This zone is wetted by meteoric water that comes from
above. Zone of non-saturation. Zone of oxidation.
Phreatic zone: lying below the water table.
This zone is wetted by water held in pore spaces.
Zone of saturation. Zone of reduction.
FLUCTUATION OFWATERTABLE
Assists greatly in flushing the laterite of dissolved material
Controls supergene enrichment of Mn and Co
66. The position of water table depends on:
Amount of rainfall
Ground porosity/permeability
Topographic characteristics
Permanently High water table
Much of rock filled with water
Less oxygen being supplied
Permanently Low water table
Likely less rainfall and little ground water to attack minerals
Slow removal of dissolved material
Fluctuating water table
Varying zones of oxidation and reduction
Frequent flushing of system to remove dissolved material
67. PARENT ROCK COMPOSITION
Rocks high in Fe yield iron laterites (mafic / ultramafic)
Rocks high in Al yield aluminous bauxites (syenites / trachytes)
Rocks with some nickel content yield nickeliferous laterites
Unserpentinised peridotites are more susceptible to weathering than
serpentinised peridotites
MINERAL GRAIN SIZE
Coarse-grained rocks are more susceptible to weathering
FRACTURES / FAULTS / JOINTS
Provide access to acidic ground waters; assist in removal of dissolved
material
STABILITYOF MINERALS
Process of chemical weathering leads to the formation of secondary
minerals that are increasingly more stable
70. In general, crystal structure of mafic silicates controls weathering:
Olivine, with its independent silicon tetrahedra is the most unstable
Pyroxenes, with polymerised chains, are more stable
Amphiboles, with their ring structures, are still more stable
Clays and micas with sheet-like structure are the most stable
Reiche (1943) devised aWeathering Potential Index:
Mineral WPI Mineral WPI
Forsterite 66 Biotite 22
Enstatite 55 Orthoclase 12
Anthophyllite 40 Quartz 0
Augite 39 Muscovite -10.7
Hornblende 36 Kaolinite -67
Talc 29 Gibbsite -300
72. The progression of clay minerals generally follows
the line of reduction of leachable components (SiO2,
MgO):
Type of clay % Leachables % Non-leachables
Nontronite 38.0 (SiO2) 50.6 (Fe2O3)
Halloysite 40.8 (SiO2) 34.6 (Al2O3)
Kaolinite 46.5 (SiO2) 39.5 (Al2O3)
Siliceous
nontronite
57.5 (SiO2) 38.2 (Fe2O3)
Montmorillonite 62.3 (CaO, MgO, SiO2) 18.3 (Al2O3)
Clinochlore 68.7 (MgO, SiO2) 18.3 (Al2O3)
73. Control of water absorption
High water run-off on steep slopes
High water absorption on moderate & gentle slopes
Water logging and saturation in basin areas
Rate of sub-surface drainage and removal of dissolved
Rate of erosion
Control of laterite preservation
Slopes of <15% are generally required to preserve the laterite
Ideal landforms for laterite development & preservation
Rolling to gently sloping morphology
Elevated area
Surface runoff is not excessive
Sub-surface drainage is good
75. pH of normal waters lies between 4 and 9
Most oxides show some solubilities in natural waters
Oxides of Ca, Mg, Na and K are completely soluble
Oxides ofTi,Al, and Ferric iron (Fe+++) are insoluble
Solubilities of many oxides are pH dependent:
Ti, Ca, Fe++ iron
Alumina is not soluble in the normal ground water pH
Alumina is soluble at pH < 4 and at pH > 10
With abundant organic matter available, pH may drop to < 4
Plant roots carry low pH values, commonly 4 but down to 2
Where abundant basic minerals are being weathered (olivine, pyroxene,
nepheline), pH conditions may climb to beyond 9
76. Redox Potential of a system is a measure of the ability to bring about reduction
or oxidation reactions
Reduction: decrease in the positive valency of an element (Fe+++ to Fe++) or an
increase in the negative valency of an element
Oxidation: increase in the positive valency of an element (Fe++ to Fe+++) or the
decrease in the negative valency of an element
The neutral value of Redox Potential is zero
At lower values (-), the R. Potential represents reducing conditions
At higher values (+), the R. Potential represents oxidising conditions
Two factors control the Redox Potential during weathering:
Atmospheric oxygen (creates oxidising conditions)
Organic matter (creates reducing conditions)
78. Laterisation rate based on mineral solubilities:
1mm/100 years; 1m/100,000 years; 10m/million years
Laterisation rate based on drainage water compositions
(P. Golightly, 1979)
1.4mm/100 years; 1.4m/100,000 years; 14m/million years
Chemical weathering in New Caledonia (Trescases, 1975)
2.9-4.7mm/100 years
Chemical weathering in Africa (Tardy, 1969)
0.5-3.3mm/100 years
Chemical weathering tends to slow down with time
Interruptions in chemical weathering
Fossil laterites
79. Water table
Water table
Regolith
Weathering Front
Thick Regolith due to
soil preservation
Thick Regolith due to
deposition of transported soil
Thin Regolith due to
soil erosion
80.
81. Ca
Na
Mg High mobility; mostly leached out
K
Si
Mn
Co Medium mobility; supergene
enrichment
Ni
Al
Cr No mobility; residual enrichment
Fe
82. Ca is present essentially in clinopyroxenes
Ca in olivines = maximum 1%
Ca in Orthopyroxenes = maximum 2%
Ca in clinopyroxenes = 22% at Sorowako; 18% at Goro
Ca is extremely soluble in ground water
Practically all Ca is leached out in the early
stages of laterisation
Final laterite residuum (goethite/limonite) have
Ca generally < 0.05%
83. Na and K present in ultramafic rocks in
extremely small quantities (< 0.1% each)
Na and K are highly soluble in ground waters
and are quickly leached out of original
ferromagnesian minerals
All Na goes to the rivers/lakes/sea
K is preferentially fixed in clay minerals
(vermiculite, montmorillonite, chlorites,
micas, illites)
Relative abundance of Na and K:
Wt.% in
earth’s crust
Wt.% in
Igneous rocks
Wt.% in
sea water
Na 2.8 2.29 1.08
K 2.6 2.22 0.04
84. Magnesia is present in Olivine, Pyroxene and Serpentine
Olivine = 57%; Enstatite = 40%; Serpentine = 44%
Magnesia is released by the breakdown of ferromagnesian
minerals
Magnesia is highly soluble in ground water
It is the first major component to be leached out in large
quantities
Some magnesia may stay in the laterite profile to form
clay minerals and nickel hydrosilicates
Final products of lateritic weathering (hematite/goethite/
limonite) do not contain any magnesia
85. Silica is present in Olivine, Pyroxene and Serpentine
Olivine = 43%; Enstatite = 60%; Serpentine = 43%
Silica is released by the breakdown of ferro-
magnesian silicates
In humid environments, laterite is constantly flushed
and little silica gets fixed as smectite/nontronite clays
In wet-dry environments, flushing of laterite profile is
poor and silica gets fixed as smectite/nontronite clays
in the Intermediate Zone
In the alkaline environment (where MgO is being
released), silica can precipitate from solution as
amorphous silica (silica veins, boxwork, coatings)
87. Iron in ultramafics: Ferrous Ferric
In olivine (MgO.FeO.SiO2) : Fe++
In pyroxene (MgO.FeO.2SiO2) : Fe++
In chromite (FeO.Cr2O3) : Fe++
In ilmenite (FeO.TiO2) : Fe++
In magnetite (FeO.Fe2O3) : Fe++ Fe+++
Fe in mafic minerals causes great instability during weathering
Breakdown of mafic minerals releases Ferrous ions
Ferrous ions are quite soluble and mobile
Ferrous ions get quickly oxidised to ferric ions, as:
Hematite / Maghemite,Goethite, Limonite
Iron in primary magnetite and ilmenite oxidises to form:
Hematite / Maghemite,Goethite, Limonite
88. Favourable conditions for the formation of
hematite and goethite (Kampf and
Schwertmann, 1983):
Temperature Excess
Moisture
Soil
Carbon
pH Altitude
Hematite High Low Low High Low
Goethite Low
< 15 C
High
> 1000mm
High
> 3%
Low High
89. Alumina is present in:
Pyroxenes (as impurity and as solid solution) 2-4%
Common Spinel (MgO.Al2O3)
On the breakdown of pyroxenes, alumina is temporarily
fixed in the chlorites (Clinochlore: 5MgO.Al2O3.3SiO2.4H2O)
After the breakdown of chlorites, alumina is fixed in
gibbsite (Al2O3.3H2O)
Alumina is very insoluble in ground water in the pH range
commonly found (4 – 9)
Al+++ and Fe+++ are truly residual elements in laterites
90. Chromite occurs in ultramafics as
Accessory chromite: FeO.Cr2O3
Ionic replacement of Mg and Fe in Olivines and pyroxenes
Trivalent Cr3+ in chromite is insoluble and very stable
Divalent Cr2+ in ferromagnesian minerals is soluble and mobile
Some Cr2+ is oxidised to Cr3+ and thus stabilised
Some Cr2+ is oxidised to Cr6+ as hexavalent oxide (CrO3) or hexavalent
chromate (CrO4)2-
Some hexavalent chrome may naturally get reduced to trivalent
chrome
Remaining hexavalent chrome may be released to the natural
environment where it is extremely toxic (carcinogenic)
91. Nickel is present in ferromagnesian minerals as ionic
replacement of Mg and Fe
Olivines: 0.3%
Orthopyroxenes: 0.1%
Clinopyroxenes: 0.05%
Serpentines: inherited from the primary mafic mineral
After breakdown of mafic minerals, Ni is released
Ni is soluble in percolating acidic waters
Ni is insoluble in alkaline waters in the saprolite zone
Ni is precipitated as hydrous nickel silicate with
serpentine, chlorite or clay structure
Some nickel is adsorbed or enters the goethite structure
92. Minor amounts of Mn and Co are present in the mafic
minerals (Olivine and Pyroxene)
On the breakdown of mafic minerals, Mn and Co are
released
Mn and Co are slightly soluble in acidic waters at the top of
the laterite profile
Mn and Co are very insoluble in alkaline waters
Mn and Co concentrate at the bottom of the Limonite
Zone
Much of Cobalt is tied to the manganese wad
102. Forsterite crystallises first (higher melting temperature)
If the olivine is allowed to react with the liquid magma, it
will change its composition towards ferrous olivine
As the larger ferrous cations replace the smaller Mg
cations, the melting temperature is progressively reduced
If the original magma has more silica than can be used by
the olivines (> 40%), then the more siliceous mafic
minerals such as pyroxenes will be formed
Olivines can take up to 0.5% of NiO (0.4% Ni)
Ni occurs as replacement of Mg atoms by Ni atoms
103. General Formula: R2Si2O6 or RO.SiO2
Orthopyroxenes:
Enstatite: MgSiO3
Ferrosilite: FeSiO3
Hypersthene: (Mg,Fe)SiO3
Clinopyroxenes:
Diopside: (Ca,Mg)SiO3
Augite: (Ca, Mg, Fe)SiO3
Wo (Ca)
En
(Mg)
Fs
(Fe)
Orthopyroxenes
Pigeonite
Augite
Diopside
Ferro-
augite
107. Olivine Serpentine
Mg2SiO4 H4Mg3Si2O9
2(MgO).SiO2 3(MgO).2SiO2.2H2O
D = 3.2 D = 2.2 – 2.4
In terms of equivalent MgO content:
6(MgO).3SiO2 6(MgO).4SiO2.4H2O
Process of serpentinisation involves:
Addition of water
Addition of silica (or removal of MgO)
Release of FeO and its oxidation to Fe3O4 (magnetite)
Lowering of bulk density (increase in volume)
108. Lizardite: (not the same as serpentinite)
Most common form
Massive
Antigorite:
Micaceous, foliated, lamellar, columnar form
Lamellae are stiff and brittle
Chrysotile:
Delicately fibrous
Fibres are flexible and easily separable
Occurs in veins or matted masses
Most common constituent of commercial “asbestos”
Hazardous to human health if fibres are inhaled
115. Hematite – Fe2O3
Non-magnetic
Formed through reduction of Ferric Hydroxides
Gives the laterite its distinctive “red” colour (laterite rouge)
Maghemite –Fe2O3 — Fe3O4
Magnetic variety of hematite
Partial reduction of hematite through forest fires?
Crystal structure closer to that of magnetite (Fe2.66 O4)
Iron deficiency in structure amounts to 11.33%
The spinel structure of maghemite inverts to the hematite structure
on heating
120. Asbolane or manganese wad is black and amorphous
It occurs as thin coatings on joints, fractures and occasionally as
nodules and beads
The material is rich in manganese and contains appreciable
quantities of Fe2O3, Al2O3, CoO and NiO
Significant amount of water of hydration may be present (12% in
a sample from New Caledonia)
Soroako
Lim. 3-6m
Soroako
Lim. 6-9m
Soroako
Lim. 9-12m
Soroako
Saprolite
New
Caledonia
Al2O3 9.0 15.0 7.0 3.5 19.2
Fe2O3 18.4 14.3 36.0 14.2 16.0
Mn2O3 31.0 33.6 33.0 32.0 39.3
NiO 1.7 3.4 2.3 16.2 n.a.
CoO 7.1 7.4 5.0 3.2 7.0
125. In nickel hydrosilicates, nickel replaces the Mg atoms
Replacement occurs in serpentine, talc and chlorite
Garnierite is a group name for nickel hydrosilicates
Garnierites have the crystal structure of serpentine, talc, or
chlorite
Garnierites are largely of supergene origin
Garnierites occur as fillings in open spaces or as coatings in joint
and fracture surfaces
Garnierites range in colour from green (light and dark), to yellow-
green, to light blue and turquoise blue. Dark green varieties carry
more nickel
126. SiO2 MgO FeO NiO
New Caledonia, sample-1 53.0 18.1 0.1 20.9
New Caledonia, sample-2 49.0 18.9 0.2 21.7
New Caledonia, sample-3 53.2 15.0 0.0 24.5
New Caledonia, sample-4 49.8 13.5 0.2 29.2
New Caledonia, sample-5 37.4 2.7 0.3 49.6
Morro do Cerisco, Brazil 43.7 30.4 5.5 5.5
Morro do Niquel, Brazil 52.9 18.3 0.2 16.8
Riddle, Oregon, USA 47.8 18.6 0.1 19.6
Riddle, Oregon, USA 52.3 16.3 n.a. 20.8
131. High Density
Bedrock zone
Variable Density
Saprolite zone
Ferruginous
zone
Bulk Density
Depth
Top
Bottom
Intermediate
zone
Ferricrete /
Silcrete
132. Run-of-mine
Wt.% / Ni
Reject
Wt.% / Ni
Recovered
Wt.% / Ni
Ni
upgrading
Sorowako W. Block
-1” ore type
100%
1.09% Ni
65%
0.6% Ni
35%
2.0% Ni 83%
Sorowako E. Block
-1” ore type
100%
1.33% Ni
55%
1.03% Ni
45%
1.7% Ni 28%
Sorowako E. Block
-6” ore type
100%
1.51% Ni
23%
0.89% Ni
77%
1.7% Ni 13%
Sorowako E. Block
-18” ore type
100%
1.59% Ni
14%
0.9% Ni
86%
1.7% Ni 7%
Bulong
High upgrading ore
100%
1.60%
25%
0.94% Ni
75%
1.82% Ni 14%
Bulong
Low upgrading ore
100%
1.58% Ni
14%
0.85%
86%
1.7% Ni 7%
Vermelho
-100# fraction
100%
0.8% Ni
49.6%
0.34%
50.4%
1.25% Ni 56%
133. 0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
0 10 20 30 40 50 60 70 80 90 100
QUANTITY OF REJECT, wt%
UPGRADING
INDEX
Values of Upgrading Index are based on a
constant Head Grade of 1.0%Ni with variable
quantity of rejects (X-axis) and variable grade of
rejects (different curves).
0.1
0.0
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
134. P.T. INCO
Saprolite zone
Ferruginous zone
Bedrock
Forms of nickel in the laterite profile
Nickel as hydroxide essentially in the
goethite-limonite structure. Some Ni
adsorbed by Mn-Hydroxides.
Nickel as hydro-silicate essentially with
the talc-serpentine-clay lattice structure:
Nickel talc
Nickel serpentine
Nickel smectites
Nickel as silicate essentially in the ferro-
magnesian minerals, as ionic
replacement of Mg and Fe atoms:
Olivine
Pyroxene
Serpentine
135.
136. Nickel grade; cobalt grade
Resource tonnage / Life of Mine / scale of operation
Ore chemistry and mineralogy
Ore consistency
Upgradeability of ore
Process selection
Availability of cheap power supply
Selection of fuel
Availability of raw materials: water, silica flux, aggregate
Availability of infrastructure
Location of project
Mining method
Environmental considerations
Negotiations with local and central governments
Funding of the project
Selection of engineer and contractor
138. New Projects:
Goro Nickel, New Caledonia 54 k
Onca-Puma, Brazil 25 k
Ravensthorpe, Australia (QNI) 50 k
Ramu River, PNG
Expansions:
Sorowako, Indonesia 22 k
Doniambo, New Caledonia 15 k
Murrin-Murrin, Australia 10 k
Under
Construction
139. New Projects:
Koniambo, New Caledonia 54 k
Vermellho, Brazil 45 k
Ambatovy, Madagascar 40 k
BarroAlto, Brazil 20 k
Fenix (Skye), Guatemala 20 k
Sorowako HPAL, Indonesia 20 k
Pomalaa HPAL, Indonesia 20-45
Expansions:
Coral Bay, Philippines 15 k
Moa Bay, Cuba 17 k
Loma de Niquel,Venezuela 17 k
140. New Projects:
Bahodopi, Indonesia
Gag Island, Indonesia
Weda Bay, Indonesia
Expansions:
Goro, New Caledonia
Sulawesi, Indonesia
Onca-Puma, Brazil
Cuba
141.
142. Pyrometallurgical processing
(Ore is melted)
Production of Ferro-nickel
Production of Ni-S matte
Hydrometallurgical processing (Leaching by acid)
PAL (Pressure acid leaching) – HPAL
EPAL (Enhanced Pressure Acid Leaching
AL (Atmospheric Leaching)
Heap Leaching
Combined pyro and hydro process (Caron)
(Ore is reduced at high temperature, then leached)
143. Project Owner Country Remarks
Cerro Matoso BHP-B Columbia
Codemin Anglo Brazil
Doniambo SLN/Eramet New Caledonia
Exmibal Ex. Inco Guatemala Mothballed
Falcondo Falconbridge Dominican Rep.
Fenimark FENI (govt.) Macedonia Closed
Hyuga Sumitomo Japan Imported ore
Larymna Larco Greece
Loma de Hiero Anglo Venezuela
Morro do Niquel Anglo Brazil Closed
Oheyama Nippon Yakin Japan Imported ore
Onca-Puma Vale Inco Brazil
PAMCO Nippon Steel Japan Imported ore
Pomalaa ANTAM Indonesia Some imported ore
144. Project Owner Country Remarks
Sorowako PT Inco Indonesia
Doniambo SLN/Eramet New Caledonia
145. Project Owner Country Remarks
Moa Bay Cuba Niquel Cuba First HPAL
Bulong Australia Shut down
Cawse Norilsk Australia
Murrin-Murrin Minara Australia
Coral Bay Sumitomo Philippines
Goro Vale Inco New Caledonia Under construction
Ramu River PNG Under construction
Ravensthorpe BHP-B Australia Under construction
146. Project Owner Country Remarks
Nicaro Union del Niq Cuba
Punta Gorda Union del Niq Cuba
Nonoc Philippines Closed
QNI BHP-Billiton Australia Imported ores
Tocantins Niquel Toc. Brazil
147. Project Owner Country Remarks
Caldag European
Nickel
Turkey First Heap Leach
project
Ravensthorpe BHP-B Australia Part of flow sheet
Murrin-Murrin Minara Australia Expansion of
project
Piaui Vale Brazil Being fast-tracked
for production
148. Ferro-Nickel Process
Upgrading in the mine
Drying of ore
Upgrading after drying
Calcining
Electric Furnace Smelting
Refining Furnace
Ferro-Nickel Product
20 – 50% Ni
Nickel-Matte Process
Upgrading in the mine
Drying of ore
Upgrading after drying
Calcining
Electric Furnace Smelting
Converting
Nickel-Matte Product
78% Ni
149. Important concerns:
Slag should not attack refractory (S/M ratio)
Melting temperature should be suitable (S/M;
Fe)
Olivine should not be introduced to the furnace
Appropriate reduction of ore prior to smelting
Ni/Fe ratio in the ore for ferro-nickel operation
150. Ore Preparation: wetting, screening
Pre Heating through flash steam
Pressure Acid Leach in autoclave
Heat recovery from leached pulp
CCD thickening and washing
Neutralisation of pregnant solution
Precipitation of metals by adding H2S/alkali
Solid/liquid separation
Ni/Co products as mixed sulphides, oxides, hydroxides
151. Important concerns:
Amounts of soluble Mg and Al in ore (acid consumers)
Acid to ore ratio required for process
Minimum operating temperature required to leach
What is the appropriate pressure during leaching
Retention time in the autoclave
Rheological behaviour during slurrying
How to recover metals in the back end of processing
What product to make
152. Ore Preparation: screening, upgrading
Drying, using oil or coal
Grinding
Reduction, using CO/H2
Ammonia leaching
CCD thickening and washing
Stripping, using steam
Calcining of Ni/Co precipitate
Sintering of calcine
Nickel oxide product
153. Nickel Sulphide Nickel Laterite
Mining Hard rock mining more
expensive. Many sulphides U/G
Soft rock mining cheap.
Only open cast mining
Deposit
uniformity
More uniform in chemistry and
mineralogy
More varied in chemistry
and mineralogy; stratified
Upgrading Highly upgradeable to sulphide
concentrate
Low upgradeability. Final
grade generally <2.0% Ni.
Ore/Con
shipping
Relatively cheap (per lb Ni) due
to high upgradeability
Relatively high (per lb Ni)
due to low upgradeability
Processing cost Modest due to high Ni content.
Sulphur provides latent heat.
High due to low Ni content.
High energy input required.
Ni recovery High due to consistency of ore
chemistry and mineralogy
Modest due to compromise
for prevalent chemistry
Capital cost Modest per lb of Ni High per lb of Ni
Project size/life Can be short to medium Long to pay for high capital
160. Packing
E.L E.L E.L
ESP
THICKENER
Scrubber
500 T
BIN
100 T
BIN
ESP
M.C
Slag to Disposal area (1500°C)
Furnace Matte (1350°C)
Electric Furnace
Silica Flux
Scrap
Converter
Matte Cast
Hot Calcine (700°C)
Wet Ore Stockpile
Dryer Kiln
Reduction Kiln
Recycle
to Dryer
Slurry
Dry Dust
Pugmill
Dust
Market
Fluid Bed
Stack
HSFO
Air
Granulation
HSFO
Air
Liquid Sulphur
Dry Dust
DKP
Dried Ore Storage
Rock
West Block (Reject)
East Block (Crushed)
Hot Gas
Water (Hi pressure)
Granulated
Matte
Oversize
(Recycle to Converter)
M.C
Air
Product Dryer
Simplified Process Plant Flow Sheet
162. For efficient operation smelter feed must meet
the following requirement:
S/M ratio 1.95 – 2.15 (optimum level of
2.05)
Iron content 20 – 23% Fe (optimum level of
21.5%)
Olivine content of <22% in any East Block batch
163. Packing
E.L E.L E.L
ESP
THICKENER
Scrubber
500 T
BIN
100 T
BIN
ESP
M.C
Slag to Disposal area (1500°C)
Furnace Matte (1350°C)
Electric Furnace
Silica Flux
Scrap
Converter
Matte Cast
Hot Calcine (700°C)
Wet Ore Stockpile
Dryer Kiln
Reduction Kiln
Recycle
to Dryer
Slurry
Dry Dust
Pugmill
Dust
Market
Fluid Bed
Stack
HSFO
Air
Granulation
HSFO
Air
Liquid Sulphur
Dry Dust
DKP
Dried Ore Storage
Rock
West Block (Reject)
East Block (Crushed)
Hot Gas
Water (Hi pressure)
Granulated
Matte
Oversize
(Recycle to Converter)
M.C
Air
Product Dryer
Drying Operation
Screening of dried ore at 3/4“ screen
- 3/4“ + 3/4“
West Block type Product.
Saved as Ore
Reject.
Discarded
East Block type Product.
Saved as Ore
Crushed.
Added to Ore
169. 18 m
Matte
Refractory bricks on
Sidewalls & hearth
Slag
Matte
Slag
Copper “fingers”
(water cooled)
Olivine mush
causing ineffective
heat transfer
170. Packing
E.L E.L E.L
ESP
THICKENER
Scrubber
500 T
BIN
100 T
BIN
ESP
M.C
Slag to Disposal area (1500°C)
Furnace Matte (1350°C)
Electric Furnace
Silica Flux
Scrap
Converter
Matte Cast
Hot Calcine (700°C)
Wet Ore Stockpile
Dryer Kiln
Reduction Kiln
Recycle
to Dryer
Slurry
Dry Dust
Pugmill
Dust
Market
Fluid Bed
Stack
HSFO
Air
Granulation
HSFO
Air
Liquid Sulphur
Dry Dust
DKP
Dried Ore Storage
Rock
West Block (Reject)
East Block (Crushed)
Hot Gas
Water (Hi pressure)
Granulated
Matte
Oversize
(Recycle to Converter)
M.C
Air
Product Dryer
• Converter Matte is cast, granulated with water sprays, dried,
screened, packed into 3-tonne polypropylene cloth bags,
and shipped to the client in Japan
• Average Product analysis: 78% Ni
1-2% Co
20% S
Converting, Granulating, Packing,
Shipping
171. E. Block
Ore
W. Block
Ore
RKF Calcine EF
Slag
EF
Matte
Product
SiO2 34.7 37.1 36.1 40.8 47.7
MgO 20.7 15.4 18.1 18.9 22.2
Fe2O3 27.7 32.0 30.0 29.2 25.9 Fe=61.5 Fe=0.5
FeO All iron reported as Fe2O3
Al2O3 3.12 2.53 2.92 2.77 3.02
Cr2O3 1.42 1.87 1.64 1.68 1.78
MnO 0.53 0.63 0.57 0.57 0.66
NiO 1.80 2.60 2.44 2.57 0.19 Ni=27.5 Ni=78.5
CoO 0.08 0.10 0.09 0.09 0.03 Co=0.76 Co=1.2
CaO 0.32 0.46 0.39 0.45 0.50
LOI ? ? ? 0.0 0.0 S=9.2 S=19.7
Total 90.86 92.69 92.25 97.03 101.98 98.96 99.90
172.
173. Eksplorasi nikel laterite merupakan salah satu
usaha bisnis yang berisiko tinggi.
Diperlukan konsep dan strategi yang matang
serta personil yang berpengalaman untuk
menjalankan bisnis tersebut.
Keberhasilan bisnis diukur dari cara
mengelola tingkat resiko dengan cara/
metode yang efektif dan efesien
174. Apa definisi eksplorasi dan Strategi eksplorasi
Kenapa strategi dan managemen eksplorasi itu
penting?
Aspek apa saja yang mempengaruhi dalam
menyusun strategi eksporasi
Strategi eksplorasi meliputi apa saja?
Bagaimana mengelola eksplorasi sebagai bisnis
yang berisiko tinggi menjadi sesuatu yang
menguntungkan
Bagaimana mengimplementasikan strategi
eksplorasi untuk cebakan nikel laterite.
175. Secara khusus definisi Eksplorasi Geologi
(Koesoemadinata,_) adalah :
“Suatu aktifitas untuk mencari tahu keberadaan
suatu objek geologi di suatu daerah atau ruang
yang sebelumnya tidak diketahui keberadaannya.
Objek geologi yang dimaksud terutama komoditi
potensi bahan galian seperti cebakan mineral,
batubara, minyak dan gas bumi ataupun air tanah.
Selain itu objek geologi dapat berupa gejala geologi
yang bermanfaat atau memiliki dampak negatif
seperti: patahan, data batuan untuk keperluan
konstruksi sipil dll.”.
176. “Suatu keahlian dalam perencanaan dan dan
pengarahan kegiatan eksplorasi yang berskala besar
dalam bentuk tahapan-tahapan yang efektif dan efisien
untuk mencari daerah yang favorable akan terdapatnya
cebakan mineral ekonomis”.
177. Kegiatan eksplorasi adalah kegiatan usaha ekonomi yg beresiko
tinggi (geologi, teknologi, ekonomi dan politik)
Paradigma eksplorasi yang tumbuh seiring dengan resiko yang
ada
• Dalam kegiatan eksplorasi sangat diperlukan pentahapan dimana pada akhir
suatu tahap dilakukan pengambilan keputusan dilanjutkan atau tidak.
• Peluang yang lebih besar tergantung pada kerapatan data, teknologi yang lebih
tinggi, personil yang lebih banyak dan waktu yang lebih lama
• Keseluruhan faktor tersebut berbanding lurus dengan biaya yang dibutuhkan
Paradigma tersebut merupakan dasar dalam menyusun Strategi
eksplorasi untuk
Menentukan urutan kegiatan eksplorasi,
Memperbesar peluang keberhasilan
Memperkecil resiko kegagalan
178. • Peluang atau probabilitas / Success ratio
• Pertaruhan dengan resiko yang sangat tinggi
• Parameter geologi (model dan kriteria geologi)
• keberadaan data yang merupakan situasi sesaat.
• Kegagalan salah satu aktifitasnya.
179. Penentuan tahapan-tahapan eksplorasi
Penentuan metode pada setiap tahapan
Penentuan target atau hasil yang diharapkan
dari setiap tahapan
Penentuan desain eksplorasi dalam setiap tahapan
Penentuan personil, peralatan dan biaya dari
setiap tahapan
180. TAHAPAN EKSPLORASI
Catatan :
Dalam penilaian daerah
prospek hanya didasar-
kan kepada
pertimbangan aspek
geologi saja
STUDI KELAYAKAN, AMDAL & PERENCANAAN TAMBANG
TAHAP EKSPLORASI PENDAHULUAN (RECONNAISSANCE)
Lingkup pekerjaan : studi pustaka, pemetaan geologi skala 1:50.000, pengambilan conto, pembuatan sumur uji (jika dipandang perlu)
dan analisa conto
TIDAK PROSPEK
TAHAP EKSPLORASI SEMI DETIL
Lingkup pekerjaan : pemetaan geologi dan topografi skala
1:5.000/ 1:10.000, pengambilan conto, pembuatan sumur uji (jika
diperlukan), pemboran pandu, survey geofisika dan geokimia,
analisa laboratorium.
PROSPEK
DISEBAGIAN WILAYAH
EVALUASI
Evaluasi Geologi Permukaan &
Bawah Permukaan-Semi Detil
TAHAP EKSPLORASI DETAIL
Lingkup pekerjaan : pemetaan geologi dan topografi skala 1:1.000/1:2.000, pengambilan conto, pemboran detil,
survey geofisika dan geokimia, analisa laboratorium, penelitian geologi teknik
Evaluasi Geologi Permukaan & Bawah Permukaan - Detil
Dilanjutkan
Dilanjutkan
DAERAH KETERDAPATAN/KP. EKSPLORASI
JIKA DATA-DATA GEOLOGI CUKUP
MEMADAI (kerapatan datanya)
LOKASI TAMBANG/ KP. EKSPLOITASI
TAHAPAN STUDI LITERATUR DAN SITE VISIT
STOP
PENYELIDIKAN TIDAK
DILANJUTKAN
181. Membuat strategi eksplorasi dan menjalankan
secara konsisten, efektif dan efesien dengan
mengurangi resiko
Memahami secara utuh model geologi daerah
eksplorasi
Improvisasi dan kompetensi geologist berperan
dalam proses evaluasi dan peningkatan tahapan
eksplorasi selanjutnya.
Pengelola eksplorasi (Manager proyek) harus
memiliki wawasan tentang orientasi bisnis
perusahaan, perkembangan teknologi eksplorasi
dan kebutuhan pasar komoditi
182. Memahami karakteristik dan model geologi nikel laterite
Memahami spesifikasi bijih untuk kebutuhan pasar
(market deman) maupun untuk rencana pembuatan
pabrik (pig iron, limonite ore dan high grade saprolite ore)
Membuat strategi eksplorasi yang efektif dan efisien
untuk nikel laterite (tahapan, metode, target, personil dan
peralatan)
Melaksanakan strategi eksplorasi secara konsisten dan
melakukan kontrol terhadap kualitas dan kuantitas data
yang dihasilkan/
Memaksimalkan data evaluasi geologi untuk perencanaan
tahapan berikutnya
183. Ada 3 jenis spesifikasi bijih nikel laterite yang
diperdagangkan secara umum
Pig Iron (Ni 1.2 – 1.4; Fe > 45%
Limonite ore (Ni 1.5 ; Fe 35%
High Grade Saprolite ore (Ni> 1.9%
185. To Located the landform characteristic based on :
Aerial photograph (smaller map scale)
landsat imagerial (Regional view)/Satellite
Aster Image
Access recognition
Cultivated Boundary
Open space area recognition.
Structural geology dan lithology interpretation.
186.
187. Significant Zn anomalies and Minor Cu Pb anomalies
TARGETING PROSPECTING -
ASTER IMAGING ANALYSIS
The green color that
represent Magnetit-
Chromite mineral has
showing good indication
Key objective : Preliminary
observation of lithology (ultramafic,
sediment, limestone, etc), alteration
(clay, silicic, laterite, gossans),
structure geology, lineament,
morphology, drainage and vegetation
anomaly for defining further
exploration target.
188. Digitizing from old data
Aanalyzing and evaluation for
previous data collected
Map Overlay and combining and
extraction for target selection
Exploration
Target
Criteria :
Slope and landform identification from landsat or
aerial photograph
Geological Condition
Drainage system
Undulating Topography
Good Laterite Profile (define from previous testpit
recognition)
189. Preliminary visit to confirm the
lithology and morphology of
the target area.
To confirm the accessibility of
the target area.
190. To define the geological condition I.e,
lithology, structure, serpentinization
and iron crust distribution.
Outcrop observation
Float mapping
Structural geology (fault, joint, fold)
Surface Sampling (assay, thin section
Float Mapping
Outcrop observation
GPS Reading
191.
192. The pit location was selected ramdomly base on topography interpretation
Tespit dimension 1.5m x 1.25 m
To provide large samples for more accurate tonnage factor and ore type fraction.
To understand the actual laterite profile characteristic
Weighing
Quartering
Enter the
Hole
Transfer Material to
surface
Bottom Pit
193. First phase core drilling for 400m stagger
Secod phase core drilling for 200 m regular spacing
Using Jacro rig with HQ size tripple tube
Objective to understand ore continuity, thickness,
chemistry distribution for resource estimation
Critical Issues:
- Quality of sample (core recovery)
-- Accuracy (deptth, interbal, etc)
195. QAQC Program is mandatory for exploration
drilling projects which will be reported under NI
43-101.
The QAQC program is to ensure a consistently
high quality work that will maintain public
confidence and assist securities regulators, at
any stage of project from pre-feasibility,
feasibility and operating mine.
This guidelines is to be implemented for
exploration and the lab. Based on this, MRMR
document will more reliable and in line with
current industry practice
196. Precision = Cluster
Accuracy = closeness to target
Bias = difference from target
Good
Accuracy &
Precision
Good Precision,
Bias
Poor Precision,
good accuracy
Poor Precision
Poor accuracy
Quality Assurance (QA) Setup system (all those planned or systematic actions
necessary to provide adequate confidence that a product or service will satisfy given
needs.
Establishment of systems and standards
Ensure quality
QualityControl (QC) Implementation (assurance in the quality context is the relief of
concern about the quality of product. Sampling plans and audits, the quality control
devices, are designed to supply part of this assurance
use of statistical tools and checks (duplicate, standard, blank, check assay and repetition)
ensure the systems are in statistical control
197. To control the preparation samples during splitting /reduce samples.
Using for calculate precision (average difference between samples)
and bias (repeatability between the duplicate pairs)
Consists of :
-Wet Duplicate
- Splitter Duplicate
- Pulp Duplicate
Drilling
Preparation
(Wet splitting)-
Wet Duplicate
Preparation
(Boyd splitting)-
Splitter Duplicate
Preparation
(CRM splitting)-
Pulp Duplicate
Lab Assaying
Pulp Duplicate
Contribute Error
Wet Dup
20 %
Splitter Dup
15 %
Pulp Dup
10 %
Pulp Dup
3 %
199. Certified references material or in- house standard.
Value is known
Allows assessment of accuracy and bias
Purpose of standards:
▪ Ensure accuracy of results
▪ Ensure required analytical precision – mechanical failure
▪ Ensure there is no bias
Ni (QC SAPO)
1.90
1.95
2.00
2.05
2.10
2.15
2.20
Bias in Ni Sap Ore, but still in
acceptable range of 3SD
Standard Sample Monitoring
200. Samples with grade less than the limit detection.
Blank sample measure the contamination cleanliness in sample
preparation
Also need to be able to compare results with immediately preceding
laboratory analyzed sample (develop QAQC program)
Blank materials are better in silica sand, but granite and granodiorite
as much better.
Ni (SPL Blank New )
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
Blank Sample Monitoringc
201. Check Assay is precision check to compare analysis data between
primary lab and secondary lab
To send 3 – 5% samples/month to External lab for checks.
Repetition is precision check to control the lab instruments (XRF)
and to control backup sample (Pulp Storage)
To send 30 samples/week to External Lab.
Repetition Samples
y = 0.9847x + 0.009
R2
= 0.9941
0
1
2
3
4
5
0 1 2 3 4 5
Ni % Previous result
Ni
%
Current
Result
Ni Comparison
y = 0.9839x + 0.0132
R2
= 0.9943
0
1
2
3
4
5
6
7
0 1 2 3 4 5 6 7
PTI Lab
Intertek
Lab
Check Assay Repetition Sample
202. DATA COMPILATION
To collect all the data I.e field data, laboratory, logging and store in
database format
Integrating the information from the various data.
Mostly store in digital data
DATAVALIDATION
Data Clean-Up, to make sure the data are ready to use and do not
contain an error, I.e:
Coordinat and grid check (drill and test pit)
Miss type of Assay value and logging data
Hole and sample number check
To combine the spread sheet assay data with location where sample was
taken
204. Evaluasi geologi adalah salah tahapan penting dalam kegiatan eksplorasi dimana
hasil evaluasi ini akan menentukan tahapan apakah suatu kegiatan eksplorasi
prospek untuk dilanjutkan/ ditingkatkan atau tidak
Setiap peningkatan tahapan eksplorasi akan memberikan konsekuensi biaya
yang sangat besar sehingga keputusan prospek atau tidak suatu wilayah
eksplorasi harus dilakukan secara akurat dan komprehensif.
Tujuan akhir dari suatu kegitan eksplorasi adalah
Mengetahui berapa besar nilai ekonomi dari endapan bahan galian disuatu daerah
Diketahui berapa banyak, besar dan kuantitas, kualitas endapan bahan galian
Besarnya, kuantitas dan kualitas dinyatakan sebagai cadangan bahan tambang.
Evaluasi geologi meliputi beberapa tahapan
Kompilasi data geologi dan penysunan database geologi
Validasi database geologi dan akuisisi data
Pengolahan data dan perhitungan cadangan
Pembuatan laporan sumberdaya dan cadangan
205. Titik Bor Easting Northing FR TO Length Ni co fe soi2 CaO Mgo
Geo
Layer
Ore Layer
BH_178 510198,92 9911099,2 0,00 1,00 1,00 0,74 0,06 41,60 7,25 <0.01 0,83 LIM OB
BH_178 510198,92 9911099,2 1,00 2,00 1,00 0,79 0,09 42,10 6,71 <0.01 0,86 LIM OB
BH_178 510198,92 9911099,2 2,00 3,00 1,00 0,95 0,09 43,20 6,95 0,01 1,98 LIM OB
BH_178 510198,92 9911099,2 3,00 4,00 1,00 1,19 0,09 37,70 16,70 0,05 5,46 LIM OB
BH_178 510198,92 9911099,2 4,00 5,00 1,00 1,51 0,04 16,40 38,80 0,32 22,20 SAP OB
BH_178 510198,92 9911099,2 5,00 6,00 1,00 2,12 0,03 11,70 10,90 0,17 27,20 SAP HGO
BH_178 510198,92 9911099,2 6,00 7,00 1,00 2,18 0,03 12,40 38,70 0,17 26,80 SAP HGO
BH_178 510198,92 9911099,2 7,00 8,00 1,00 2,44 0,03 12,80 38,10 0,16 26,80 SAP HGO
BH_178 510198,92 9911099,2 8,00 9,00 1,00 2,38 0,04 13,80 36,70 0,18 25,30 SAP HGO
BH_178 510198,92 9911099,2 9,00 10,00 1,00 1,60 0,02 8,56 41,20 0,31 32,70 SAP BZ
BH_178 510198,92 9911099,2 10,00 11,00 1,00 1,38 0,03 10,30 41,60 0,26 29,60 SAP BZ
BH_178 510198,92 9911099,2 11,00 12,00 1,00 1,33 0,03 12,80 42,40 0,38 24,20 SAP BZ
BH_178 510198,92 9911099,2 12,00 13,00 1,00 1,18 0,03 10,60 42,40 0,23 28,10 SAP BZ
207. Metode perhitungan coventional (Geometrik)
Section
Isochore
Poligonal
▪ Included area
▪ Extended area (regular grid)
▪ Triangle
▪ Bi-sect polygon
Metode perhitungan Moderen (geostatistik)
Linear regresion
Inverse distance
Kriging
208.
209. Strategi eksplorasi adalah sangat penting dan
merupakan kunci keberhasilan dalam
kegiatan eksplorasi
Kegiatan eksplorasi yang dikelola dengan
baik akan memberikan hasil yang optimal,
efektif dan efesien serta mengurangi resiko
yang timbul
Evaluasi geologi merupakan kunci layak
tidaknya suatu tahapan eksplorasi untuk
dilanjutkan atau tidak.
