Modeling
Refining Unit Process Stage
The refining process begins with nickel matte or crude nickel products’ delivery to the refining stage and
ends at the gate to delivery of the finished nickel products. The following sections provide more detail of
the technologies, processes, and modeling.
Matte refining into Class I Nickel
Matte refining into class 1 nickel begins with crushing, leaching, and separation of matte. One
questionnaire is sent for the crushing-leaching-separation stage due to the metal-containing coproducts.
The subsequent four stages, concentration of iron and cobalt, purification, and electrolysis, also each are
their own black box.
A mass allocation of the metal in the coproducts is made for each black box. The SOx allocation rule
applies to the leaching/separation stage.
Nickel Matte from Oxidic Ore or
Nickel Matte from Sulfidic Ore
Crushing
Cl2 leaching and
separation
Cu, Se
S to S
material
plant, as S
Chloride solution (Ni, Co, Fe) from refining leaching
H2SO4
plant
Cu, PGMs
Iron concentration
Nickel Chloride solution
(Fe separated)
Solvent
extraction,
treating
NiCl2 to
crystallisation
FeCl3 (reused, or to concentration
plant)
Cobalt concentration
Nickel Chloride solution
(Fe, Co separated)
Purification
CoCl, NiO, CoO
NiCl
2
Nickel Chloride solution
Electrolysis - cutting
Ni metal (class I)
Figure 29 Refining: Class 1 Ni Production from Matte (Integrated Facility)
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H2SO4
Modeling
Some facilities’ processes are not as integrated as those in Figure 29. Matte here may be leached
(producing coproducts), and then undergoes electrolysis to produce Class 1 nickel.
Separate data are collected to allocate the leaching flows to the metal coproducts, and a mass allocation
on the metals is made.
Nickel Matte from Oxidic Ore or
Nickel Matte from Sulfidic Ore
Leaching
Liquor
Co, Cu, Fe,
PGM
Nickel Chloride solution
Electrolysis
Ni metal (class I)
Figure 30 Refining: Class 1 Ni Production from Matte (Less Integrated Facility)
Hydrosulfidic Refining
Case 1
The processes for hydrosulfidic refining include electrorefining and electrolyte purification of nickel
matte (or sulfide anodes) to produce CoO and Ni cathodes. Only one black box is considered since the
CoO as a coproduct occurs at purification. A mass allocation on the metals is made.
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Modeling
Nickel Matte from Oxidic Ore or
Nickel Matte from Sulfidic Ore
Electrorefining
Spent anodes
and
impureanolyte
Purified
electrolyte
Electrolyte
purification
CoO
Nickel Cathode (deposit)
Figure 31 Refining (Hydrosulfidic): Ni Cathode Production from Nickel Matte (Part 1)
Ni cathodes are then shipped to another location which produces nickel products, according to the figure
below. Only one black box is needed for this process.
Nickel Cathode (deposit)
Nickel product
services
(shearing,etc. …)
Nickel metal (class I)
Nickel Powder
Figure 32 Refining (Hydrosulfidic): Ni Products Production from Ni Cathodes (Part 2)
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Modeling
Case 2a and 2b
Another hydrosulfidic refining process takes nickel cobalt sulfide or nickel matte and goes through the
following processes to produce Class 1 nickel products: leaching, cobalt and copper extraction, nickel
reduction, sulfide precipitation, and nickel handling, as shown in Figure 33a and b below:
(a)
(b)
Nickel Cobalt Sulfide
Nickel matte (Ni, Co, Cu, FeS)
Hexammine Leach
Fe Residue
Nickel Sulfate (iron separated)
Fe Residue
Cobalt Separation
Cobalt Sulfate
Nickel Sulfate (cobalt separated)
CuS
Copper Removal
Nickel Sulfate
(iron and copper separated)
Copper Removal
CuS
Nickel Sulfate
(Co and copper separated)
Nickel Reduction &
Sulfide precipitation
Reduced Nickel
(intermediate product)
Hexammine Leach
Nickel cobalt
sulfide
AMSUL
Nickel Reduction &
Sulfide precipitation
Reduced Nickel
(intermediate product)
Nickel Handling
Nickel Handling
Nickel Products
Nickel Products
ZnS
AMSUL
Figure 33a and b Refining (Hydrosulfidic): Ni Products Production from Nickel Cobalt Sulfide and Nickel
Matte
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Modeling
Case 3
A third hydrosulfidic refining case occurs by putting nickel matte through the following processes to
produce Class 1 nickel and nickel briquettes: grinding and leaching, cobalt removal, and electrowinning
and hydrogen reduction, as shown in Figure 34 below:
Nickel Matte from sulfidic Ore
Fe,
CuS
Grinding & Leaching
Nickel Sulfate Solution (Fe separated)
Cobalt removal (with
solvent extraction)
Cobalt
sulfate
Nickel Sulfate Solution (Fe, Co
separated)
Electrowinning &
Hydrogen reduction
Nickel Metal (Class I), Nickel briquettes
Figure 34 Refining (Hydrosulfidic): Ni Products Production from Nickel Matte
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Modeling
Case 4
A fourth hydrosulfidic refining case occurs by putting various nickel feeds through the following
processes to produce Class 1 nickel and a nickel-cobalt slurry: grinding and leaching, nickel purification,
roasting, and nickel electrolysis and cutting (see Figure 35).
Nickel Matte from sulfidic Ore
Miscellaneous Ni-bearing mat. from off-site
Feed solutions from on site recirculation
Grinding
Iron
Cl2 leaching
Nickel Chloride Solution (Fe
separated)
Cl2 leach residue
NiCO3 slurry
H2SO4
Nickel purification
Pb, and Co
Roasting
SO2 to S
abatement
Cu-leach
resiude
Nickel Chloride Solution (Fe,
Co separated)
Nickel Electrolysis
& cutting
Ni Metal (Class I)
NiCO3 slurry
Figure 35 Refining (Hydrosulfidic): Ni Products Production from Various Nickel Feeds
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Modeling
Caron Process
For this process, nickel cobalt liquor undergoes solvent extraction to separate the nickel and cobalt into
different product streams. The nickel liquor is then converted to a slurry and refined to produce Class 1
nickel metal and nickel oxide. The cobalt liquor is further refined and then precipitated to produce cobalt
oxide hydroxide (with a mass allocation made on the metals content in the two products). The slurry is
then reduced to produce Class 1 nickel metal and nickel oxide. A total mass allocation is made for these
two nickel products.
Nickel Cobalt Liquor
Solvent
Extraction
Cobalt Oxide
Hydroxide
NiCO 3 slurry
Calcination
Reduction
Ni metal
(class I)
NiO
Figure 36 Caron Process: Ni products Production from Nickel Cobalt Liquor
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Modeling
Carbonyl Process
The carbonyl process involves processing nickel and copper metallics and nickel oxide to produce crude
liquid carbonyl, which is further processed into Class 1 nickel and ferronickel. A mass allocation is made
between the mass of the nickel content in the crude liquid carbonyl and the metals contained in the
Integrated Pressure Carbonyl (IPC) residues in the first process box, considered a black box. A total
mass allocation is made on the Class 1 nickel and ferronickel produced at the end.
Nickel metal from primary extraction
Copper metal from primary extraction
Nickel Oxide (NiO)
Natural Gas
reforming
Feed preparation
CO
H2, N.G., N 2
Incineration
Integrated Pressure
Carbonyl (IPC)
Residues to Co refinery
Pressure carbonyl reactors
Crude Liquid Carbonyl (intermediate product)
Distillation columns
Vaporizers
Ferronickel (FeNi)
Nickel metal
(Class I)
Nickel Powder
Figure 37 Refining: Class 1 Ni and FeNi Production with Cu/Ni Metallics and NiO (Carbonyl Process)
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Modeling
Pyrometallurgical Refining of NiO
Pyrometallurgical refining of nickel includes reduction of nickel oxide and subsequent volatilization into
Class 1 nickel and nickel sulfate. A mass allocation is made on the nickel content of these two products.
One black box is considered for this process.
Nickel Oxide ( NiO)
Reduction Kiln
Ni
H2
Natural gas
reforming
CO
Volatiliser Kiln
Ni Pellet/Powder decomposers
Nickel Sulphate plant
Nickel metal (Class I)
Nickel powder
NiSO4*6H2O
Figure 38 Refining (Pyrometallurgical): Class 1 Ni Production from NiO
Treatment of Shared Processes at the Same Facility
Introduction
Careful modeling of shared processes on-site is done due to their inclusion in nickel-related processes and
the allocation to each respective unit process to which they deliver their function. The shared processes
considered in this study include:
•
Wastewater treatment plant (WWTP);
•
Power plant; and
•
S-abatement plant.
Shared on-site processes deliver their function inside and outside the study system boundaries.
Therefore, care is taken to account for only the flows for which nickel products are responsible. This
procedure is described in the next section.
Allocation of Shared Processes to Each Unit Process
Using WWTP at a mining/beneficiation site as an example, the total inflows and outflows of the WWTP
(i.e., for 1998) are collected, as well as direct site release, and are allocated to mining and beneficiation
(see Table 9), as if there were a separate WWTP for each process. This method was chosen because it
would produce the more accurate results than other allocations means: knowing the overall inputs and
outputs and estimating the percent contribution to each process was thought to be more accurate than
providing water effluent values for each individual process (another method of applying shared process
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