Continuous hydrometallurgical process for producing mixed hydroxide precipitate

Abstract

Disclosed examples generally relate to a continuous hydrometallurgical process for the production of mixed hydroxide precipitate from nickel sulfide concentrates. In at least one example, the process includes comprising: (a) mixing a sulphur deficient nickel sulphide concentrate with sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase; (b) primary neutralization of the aqueous phase of the leach slurry with a neutralizing agent for removal of at least one impurity to form a neutralized pregnant leach solution (PLS) having at least one primary metal; and (c) secondary neutralization of PLS to precipitate MHP and conducting solid / liquid separation to produce MHP product and MHP filtrate. In some examples, the process further enables production of high purity nickel sulphate crystals from the MHP product without the need for nickel solvent extraction. This may provide a simplified route to battery-grade nickel sulphate suitable for precursor cathode active material synthesis.

Description

TITLE: CONTINUOUS HYDROMETALLURGICAL PROCESS FOR PRODUCING MIXED HYDROXIDE PRECIPITATECROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] The present application claims the benefit of, and priority to, United States ProvisionalPatent Application No. 63 / 689,135, filed on August 30, 2024, the entire contents which are incorporated herein by reference.FIELD

[0002] Various examples are described herein that generally relate to production of mixed hydroxide precipitate (MHP), and in particular, to a continuous hydrometallurgical process for producing mixed hydroxide precipitate.BACKGROUND

[0003] Nickel is one of the critical metals used for production of precursor cathode active materials (pCAM) of lithium-ion batteries (LIBs). Cobalt is also an important metal used for LIB production as known in the art. The use of nickel and cobalt, containing mixed hydroxide precipitate (MHP), is expected to continue to increase to allow for the production of LIBs for electrification, all the while the supply of economically and environmentally recoverable natural resources is gradually decreasing.SUMMARY OF VARIOUS EMBODIMENTS

[0004] In accordance with one broad aspect, there is provided a continuous, hydrometallurgical process for producing mixed hydroxide precipitate (MHP) comprising: mixing a sulphur deficient nickel sulphide concentrate with sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase; primary neutralization of the aqueous phase of the leach slurry with a neutralizing agent for removal of at least one impurity to form a neutralized pregnant leach solution- 1 -WSLEGAL\097549\00002\41667351v6(PLS) having at least one primary metal; and secondary neutralization of PLS to precipitate MHP and conducting solid-liquid separation to produce MHP product and MHP filtrate.

[0005] In some examples, the process further comprises blending an excess sulphur containing feeds, such as nickel concentrate or iron sulphides (i.e. pyrite, pyrohotite), with the sulphur deficient nickel concentrate.

[0006] In some examples, the process further comprises a tertiary neutralization of the MHP filtrate to produce a scavenger precipitate and a scavenger filtrate.

[0007] In some examples, the process further comprises mixing the scavenger precipitate with the leach slurry for recovery of at least one primary metal.

[0008] In some examples, the process further comprises a quaternary neutralization of the scavenger filtrate to produce a solid residue for tailing.

[0009] In some examples, the process further comprises precipitating high-grade, very low impurity MHP.

[0010] In accordance with another broad aspect, there is provided a hydrometallurgical process for producing nickel sulphate product, comprising: mixing a sulphur deficient nickel sulphide concentrate with sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase; primary neutralization of the aqueous phase of the leach slurry with a neutralizing agent for removal of at least one impurity to form a neutralized pregnant leach solution (PLS) having at least one primary metal; and secondary neutralization of PLS to precipitate MHP and conducting solid-liquid separation to produce MHP product and a MHP filtrate; leaching the MHP with sulphuric acid and water to form a second pregnant leach solution (SPLS); subjecting the SPLS to impurity extraction to produce an impurity raffinate; and nickel extraction from the impurity raffinate to produce a nickel sulphate solution product.

[0011] In some examples, the process further comprises crystalizing the nickel sulphate solution product to form hydrated nickel sulphate crystals.

[0012] In another broad aspect, there is provided a hydrometallurgical process for producing nickel sulphate product, comprising: mixing a sulphur deficient nickel sulphide concentrate with- 2 -WSLEGAL\097549\00002\41667351v6sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase; primary neutralization of the aqueous phase of the leach slurry with a neutralizing agent for removal of at least one impurity to form a neutralized pregnant leach solution (PLS) having at least one primary metal; and secondary neutralization of PLS to precipitate MHP and solid-liquid separation to produce MHP product and a MHP filtrate; leaching the MHP with sulphuric acid and water to form a second pregnant leach solution (SPLS); and subjecting the SPLS to impurity extraction to produce an impurity raffinate to yield a nickel sulphate solution product.

[0013] In some examples, the process further comprises crystalizing the impurity raffinate to form hydrated nickel sulphate crystals.

[0014] In some examples, the process further comprises neutralization of the impurity raffinate with a neutralizing agent to form a high-grade, very low impurity nickel hydroxide product.

[0015] In some examples, the process further comprises a tertiary neutralization of the MHP filtrate to produce a scavenger precipitate and a scavenger filtrate.

[0016] In some examples, the process further comprises a quaternary neutralization of the scavenger precipitate filtrate to produce a tailing.

[0017] In some examples, the process further comprises blending an excess sulphur containing nickel concentrate with the sulphur deficient nickel concentrate.

[0018] In some examples, the sulphur deficient nickel sulphide concentrate has a particle size of greater than 40 pm, more specifically in between 40 pm and 80 pm.

[0019] In some examples, the nickel sulphide concentrate has molar ratio of sum of the acid consuming metals (Ni+Co+Al+As+Mg+Mn+Cr+Cu+Zn) to total sulphur in the range of 0.8 to 3.0.

[0020] In some examples, the mixing occurs at a minimum temperature of 140°C.

[0021] In some examples, the mixing occurs at an oxygen partial pressure of between 600 to750 kPa, preferably in between 650 to 750 kPa and more preferably 690 kPa.

[0022] In some examples, the leaching occurs over a residence time of at least 2 hours.

[0023] In some examples, the total sulphur oxidation occurs in the range of about 95% to 99%.- 3 -WSLEGAL\097549\00002\41667351v6

[0024] In some examples, the MHP recovers >97.0% nickel and cobalt.

[0025] In some examples, the nickel hydroxide recovers >97.0% nickel. In another broad aspect, there is provided a continuous, hydrometallurgical process for producing mixed hydroxide precipitate (MHP) comprising: mixing a sulphur deficient nickel sulphide concentrate with sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase; wherein the mixing the sulphur deficient nickel sulphide concentrate has a nominal particle size of greater than 48 pm, occurs at a minimum temperature of 140°C, at an oxygen partial pressure of between 600 to 750 kPa, preferably in between 650 to 750 kPa and more preferably 690 kPa, over a residence time of 2 to 4 hours and the consumption of sulphuric acid is no greater than 850 kg / t sulphide nickel concentrate.

[0026] In some examples, the leaching of the sulphur deficient nickel sulphide concentrate produces a stable solid tailing consisting primarily of magnetite and hematite iron minerals.

[0027] In some examples, the process further comprises about 99% leach recovery of Ni and Co from MHP at a pH between 3.0 and 4.0 with a sulphuric acid solution, without the addition of any redox reagents such as hydrogen peroxide (H2O2), under atmospheric pressure and elevated temperature to produce secondary pregnant leach solution (SPLS).

[0028] In some examples, the process comprises production of an impurity / cobalt raffinate comprising nickel sulphate solution with a high nickel concentration of more than 80 g / L, and low impurity levels comprising <5 mg / L Ca, <12 mg / L Mg and <700 mg / L Na, without any nickel solvent extraction.

[0029] In some examples, the nickel sulphate solution is used directly for pCAM synthesis or crystallization to produce hydrated nickel sulphate crystals.

[0030] Other features and advantages of the present application will become apparent from the following detailed description taken together with the accompanying drawings. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the application, are given by way of illustration only, since various changes and modifications within the spirit and scope of the application will become apparent to those skilled in the art from this detailed description.- 4 -WSLEGAL\097549\00002\41667351v6BRIEF DESCRIPTION OF THE DRAWINGS

[0031] For a better understanding of the various embodiments described herein, and to show more clearly how these various embodiments may be carried into effect, reference will be made, by way of example, to the accompanying drawings which show at least one example embodiment, and which are now described. The drawings are not intended to limit the scope of the teachings described herein.

[0032] FIG. 1A is an example process flow for a continuous hydrometallurgical process for producing mixed hydroxide precipitate (MHP) product.

[0033] FIG. IB is a continuation of the process flow in FIG. 1A and is an example process flow for producing and reusing scavenger filtrate as well as scavenger precipitate.

[0034] FIG. 1C is an example process for producing one or more additional products from the MHP product produced in the process flowsheet of FIG. 1 A.

[0035] FIG. ID is another example process for producing one or more additional products from the MHP product produced in the process flowsheet of FIG. 1A.

[0036] FIG. IE is still another example process for producing one or more additional products from the MHP product produced in the process flowsheet of FIG. 1A.

[0037] FIG. 2 is an example flowsheet for a continuous hydrometallurgical process for producing MHP product.

[0038] FIG. 3 is a flowsheet of an example process for producing, from MHP product, one or more of cobalt hydroxide product, hydrated nickel sulphate crystal product and sodium sulphate crystal product.

[0039] FIG. 4 A shows a portion of the flowsheet of FIG. 3 relating to the production of cobalt hydroxide product.

[0040] FIG. 4B shows a portion of the flowsheet of FIG. 3 relating to the production of hydrated nickel sulphate crystal product.

[0041] FIG. 4C shows a portion of the flowsheet of FIG. 3 relating to the production of sodium sulphate crystal product.- 5 -WSLEGAL\097549\00002\41667351v6

[0042] FIG. 5 is a flowsheet of another example process for synthesizing, from MHP product, one or more of cobalt hydroxide product, hydrated nickel sulphate crystal product and sodium sulphate crystal product.

[0043] FIG. 6 A shows a portion of the flowsheet of FIG. 5 relating to the production of cobalt hydroxide product.

[0044] FIG. 6B shows a portion of the flowsheet of FIG. 5 relating to the production of hydrated nickel sulphate crystal product.

[0045] FIG. 6C shows a portion of the flowsheet of FIG. 5 relating to the production of sodium sulphate crystal product.

[0046] FIG. 7 is a flowsheet of another example process for synthesizing, from MHP product, one or more of cobalt sulphate crystal product, nickel sulphate solution and crystal products and sodium sulphate crystal product.

[0047] FIG. 8A shows a portion of the flowsheet of FIG. 7 relating to the production of impurity raffinate.

[0048] FIG. 8B shows a portion of the flowsheet of FIG. 7 relating to the production of cobalt sulphate crystal product.

[0049] FIG. 8C shows a portion of the flowsheet of FIG. 7 relating to the production of nickel sulphate solution and crystal products, and cobalt and nickel hydroxide precipitate.

[0050] FIG. 8D shows a portion of the flowsheet of FIG. 7 relating to the production of sodium sulphate crystal product.

[0051] FIG. 9 A is a photograph of MHP product.

[0052] FIG. 9B is a photograph of hydrated nickel sulphate crystals.

[0053] FIG. 10 is a plot of an XRD pattern of a POX leach residue.

[0054] Further aspects and features of the example embodiments described herein will appear from the following description taken together with the accompanying drawings.- 6 -WSLEGAL\097549\00002\41667351v6DETAILED DESCRIPTIONI. GENERAL OVERVIEW

[0055] As discussed previously, the demand for nickel and cobalt is consistently increasing with the rapid advancement of lithium-ion batteries (LIBs) for use in clean technologies and energy storage.

[0056] To this end, traditional pyrometallurgical smelting processes typically use nickel sulphide concentrates to produce nickel mattes for supplying the stainless-steel and LIB industries. Traditional methods of pyrometallurgical processing of sulphide concentrates, however, are becoming less attractive due to a host of factors, including their adverse environmental footprint, undesirable gaseous emissions, production of dusts, as well as losses of valuable metal by-products in slags and residues discharged from pyrometallurgical processing plants.

[0057] In view of the foregoing, disclosed examples relate to a continuous hydrometallurgical process for producing mixed hydroxide precipitate (MHP) product. The disclosed hydrometallurgical process is believed to minimize the environmental impact of processing sulphide concentrates and can be used to convert nickel sulphide concentrates into MHP, which is a key precursor for electric vehicle (EV) batteries.

[0058] In at least one example, the disclosed hydrometallurgical process uses a pressure oxidation (POX) leaching process for the recovery of nickel and cobalt from sulphide concentrates. The POX leaching process produces a leach slurry which then undergoes pH adjustment with limestone to remove impurities, including aluminum and iron. The purified leach slurry is then subject to solid-liquid separation to separate a pregnant leach solution (PLS), which is used to produce MHP product using magnesia.

[0059] As discussed herein, the disclosed POX-based method demonstrates over 97% nickel and cobalt extraction, and in some examples, 99% nickel and cobalt extraction from nickel sulphide concentrate, which has molar ratio of sum of the acid consuming metals (Ni+Co+Al+As+Mg+Mn+Cr+Cu+Zn) to total sulphur in the range of 0.9 to 3.0, under relatively mild conditions (e.g., 150°C and 690 kPa oxygen overpressure).- 7 -WSLEGAL\097549\00002\41667351v6

[0060] More generally, almost all iron and aluminum are selectively precipitated over nickel and cobalt from the POX autoclave discharge slurry using limestone with -0.8% Ni and -0.7% Co deported to solid residues, which suggests that one stage neutralization is sufficient for impurity removal. Sulphur oxidation is also increased with increasing residence time and occurs in a range of about 95% to 99%. In at least one example, sulphur oxidation reaches >96.7% within 4 hours of residence time. Mixed hydroxide precipitation tests also suggest that high grade MHP can be produced by stoichiometric magnesia addition with a minimal impurity.

[0061] As provided herein, the disclosed process can be used to produce relatively clean and high-grade MHP containing very low impurities, such as iron, aluminum, copper, manganese, and zinc. The MHP product can be used as a feed for making nickel and cobalt salts as well as to directly produce precursor cathode active materials (pCAM) for LIBs.

[0062] The exemplified process is believed to have many advantages over conventional pyrometallurgical treatment, including minimizing the emission of gases and dusts, converting sulphide sulphur into sulphuric acid, which is consumed by the process, producing high-grade, low impurity MHP with higher recovery of nickel and cobalt, and treating high magnesium containing nickel sulphide concentrates. The disclosed process also reduces environmental concerns relating to traditional smelting processes and decreases the operating costs by simplifying the process flowsheet.

[0063] Disclosed examples generally can be implemented in either a batch or continuous process.

[0064] Various features of the continuous hydrometallurgical process for producing MHP product are now described herein.- 8 -WSLEGAL\097549\00002\41667351v6II. EXAMPLE CONTINUOUS HYDROMETALLURGICAL PROCESSES FOR PRODUCING MIXED HYDROXIDE PRECIPITATE (MHP) PRODUCT

[0065] The following is a discussion of continuous hydrometallurgical processes for producing MHP product.

[0066] (i.) Example Process for Producing MHP Product

[0067] FIG. 1A shows an example process for a continuous hydrometallurgical process for producing MHP product from nickel sulphide concentrates. The produced MHP product contains nickel and cobalt precipitate products, e.g., nickel and cobalt hydroxides.

[0068] Concurrent reference is also made to FIG. 2, which illustrates a flowsheet 200 for producing MHP product using a continuous hydrometallurgical process. At a general level, the flowsheet 200 includes the following process steps: feed preparation, POX leaching, re-leaching and impurity removal, solid-liquid separation, MHP production, scavenger precipitation, and effluent treatment.

[0069] As shown in FIG. 1A, at act 102a, the process initially begins by processing sulphur deficient nickel concentrate to produce a POX leach slurry.

[0070] The sulphur deficient nickel concentrate, used at act 102a, may be produced by processing ore by conventional methods known in the art. For example, this includes flotation and magnetic separation to produce nickel concentrate for the hydrometallurgical flowsheet.

[0071] In at least one example, the sulphur deficient nickel concentrate has a particle size greater than 40 pm, and more preferably in a range of 40 pm and 80 pm. The sulphur deficient nickel concentrate may further have a molar ratio of sum of acid consuming metals (e.g., Ni+Co+Al+As+Mg+Mn+Cr+Cu+Zn) to total sulphur in the range of approximately 0.8 to 3.0.

[0072] To this end, the particle size distribution (PSD) of the nickel sulphide concentrates was determined by standard screen analysis. Representative samples were dried, weighed, and passed through a series of sieves with decreasing mesh sizes. The material retained on each sieve was collected, weighed, and expressed as a percentage of the total sample mass to establish the cumulative particle size distribution profile of the concentrate.- 9 -WSLEGAL\097549\00002\41667351v6

[0073] In some cases, the sulphur deficient nickel concentrate is blended with excess sulphur containing feeds, such as nickel concentrate or iron sulphides (i.e. pyrite, pyrohotite), to increase the amount of sulphur content in the nickel concentrate.

[0074] As shown in flowsheet 200 in FIG. 2, act 102a (FIG. 1A) may involve mixing the sulphur deficient nickel concentrate with sulphuric acid (H2SO4), water and oxygen. The mixture is then subject to pressure oxidation 202 which can be performed, for example, in an autoclave. This, in turn, produces a leach slurry 204.

[0075] To this effect, the addition of oxygen in the mixture can assist in the oxidation of the sulphide minerals to produce sulphates, as expressed in the Equations below. The addition of water can assist in slurry formation, temperature control as well as certain precipitation and oxidation reactions. Sulphuric acid assists in the leaching and dissolution of various metals in the concentrate, as well as breaking down gangue material.

[0076] In at least one example, the mixing in the autoclave occurs under relatively mild conditions and may be performed at a minimum temperature of 140°C and a minimum oxygen partial pressure of 600 kPa. The residence time may be at least 2 hours, and more preferably between 2 to 4 hours. In some examples, the consumption of sulphuric acid during pressure oxidation is no greater than 850 kg / t sulphide concentrate. In some examples, the oxygen partial pressure in the autoclave is between 600 to 750 kPa, preferably between 650 to 750 kPa and more preferably 690 kPa. As used herein, pressure is expressed relative to atmospheric pressure.

[0077] During pressure oxidation, the primary chemical reactions occurring in the autoclave to release nickel and cobalt from unwanted gangue metals, in the nickel sulphide concentrate, is expressed by Equations (1) - (8):• Pentlandite oxidation:(Fe, Ni)9S8+ 9 H2SO4 + 4.54.5 NiSO4+ 4.5 FeSO4+ 8 S + 9 H2O (1)• Heazlewoodite oxidation:- 10 -WSLEGAL\097549\00002\41667351v6• Cobaitpentlandite oxidation:(Fe, Co, Ni)9S8+ 9 H2SO4+ 4.5• Lizardite leaching:• Brucite leaching:Mg(OH)2+ H2SO4MgSO4+ 2 H2O (5)• Sulphur Oxidation:S + 1.5 O2+ H2O - H2SO4(6)• Ferrous Oxidation2 FeSO4+ 0.5• Iron Precipitation

[0078] Continuing with reference to FIG. 1 A, at act 104a, the leach slurry is subject to primary neutralization to form a neutralized leach slurry.

[0079] As shown in the flowsheet 200 in FIG. 2, the POX slurry 204 is subject to a primary neutralization 206 by mixing the leach slurry 204 with a primary neutralizer in presence of an oxidizer(e.g., air, oxygen or hydrogen peroxide). The result is a neutralized leach slurry 208. The purpose of the primary neutralization is to facilitate precipitation of certain metal ions that are not of interest to the process, such as aluminum (Al), iron (Fe), chromium (Cr) and to a lesser extent copper (Cu). The leach slurry 208 can be subjected to solid-liquid separation 210 to then separate a pregnant leach solution (PLS) 212.

[0080] In this example, the primary neutralizer is selected as calcium carbonate, Ca(CO3) (i.e., limestone) and oxidizer is selected as air. Further, the primary neutralization may be conducted at elevated temperatures with at least 2 hours of residence time. In some examples, the primary- 11 -WSLEGAL\097549\00002\41667351v6neutralization is performed at conditions of at least about 70°C, and more preferably at least about 75°C. The primary neutralizer may be added in an amount to achieve a target pH between about 3.0 and 5.0, and more preferably about 3.0 and 4.0.

[0081] In more detail, the POX slurry 204, obtained from the autoclave at 202, is rich in nickel with low concentration of metals including aluminum (Al), iron (Fe), and chromium (Cr), as well as low content of free sulphuric acid (H2SO4). The primary neutralization is accordingly carried out on the autoclave discharge slurries to remove at least one of these impurities using limestone. The following chemical reactions, shown in Equations (9) - (12), may occur during the primary neutralization of leach slurry to precipitate Fe and Al:

[0082] As shown in flowsheet 200 (FIG. 2), the leach slurry 208 is then subject to solid / liquid separation 210, and which may involve addition of water for washing the solids residue. This allows separating the PLS 212 from the residue precipitate 246. The PLS 212 includes the metals of interest (e.g., nickel and cobalt). The residue precipitate 246 includes the undesired metals, from POX leach residue and as resulting from Equations (9) - (12). For example, this includes precipitated calcium sulfate dihydrate (CaSO4*2 H2O), iron (III) hydroxide (Fe(OH)3) and aluminum hydroxide (A1(OH)3). In some examples, iron (Fe) and aluminum (Al) are also precipitated, and chromium (Cr) and copper (Cu) to a lesser extent.

[0083] At act 106a (FIG. 1 A), mixed hydroxide precipitation is applied to the PLS 212 to form an MHP slurry, through a secondary neutralization. The purpose of the MHP precipitation is to precipitate both nickel and cobalt hydroxides, which can then be used in downstream flowsheets, as provided herein. For example, the nickel and cobalt hydroxides can be used for producing cobalt product, nickel sulphate crystal product.- 12 -WSLEGAL\097549\00002\41667351v6

[0084] As shown in the flowsheet 200 (FIG. 2), the PLS is subject to MHP precipitation 214. The MHP precipitation 214 occurs through a second neutralization, using a second neutralization agent. In this example, the second neutralization agent is magnesia (MgO). In at least one example, magnesia is selected to eliminate foreign ions e.g., Ca and Na in the product, as Mg is already present in the PLS.

[0085] In some examples, the MHP precipitation step 214 is performed with a residence time of at least about 2 hours. The temperature may be in a range of about 40°C to 70°C and more preferably, between about 50°C and 60°C. The neutralization agent (e.g., MgO) added may be at least 70% of the stoichiometric amount, and preferably, 90% of the stoichiometric amount, to reach pH of between about 6.5 and 7.5, and preferably a pH of between about 6.75 to 7.25.

[0086] As noted, the purpose of the second neutralization is to precipitate the metals of interest, e.g., as hydroxides. To this effect, the chemical reactions, expressed by Equations (13) - (14), may occur during the mixed hydroxides precipitation:NiSO4+ MgO + H2O Ni(0H)2+ MgSO4(13)CoSO4+ MgO + H2O CO(OH)2+ MgSO4(14)

[0087] As further exemplified in the flowsheet 200 (FIG. 2), an MHP slurry 216 is formed by the MHP precipitation 214. The MHP slurry 216 is subjected to solid / liquid separation 220. The solid / liquid separation 220 separates the final solid MHP product 222 from the MHP filtrate 224. In this manner, the target metals - nickel and cobalt hydroxides - are precipitated. In some examples, the MHP product 222 may then be used as a feed for making nickel and cobalt sulphate products as well as to directly produce pCAM of LIB s.

[0088] In at least one example, the resulting MHP filtrate 224 is disposed of. In other examples, the MHP filtrate 224 is subjected to further processing, as explained below in method 100b (FIG. IB).- 13 -WSLEGAL\097549\00002\41667351v6

[0089] (ii.) Example Process for Continued Refinement of MHP Filtrate

[0090] FIG. IB shows an example process for continued refinement of the MHP filtrate for further production of MHP product. Concurrent reference is still made to the flowsheet 200 (FIG. 2).

[0091] At 102b (FIG. IB), tertiary neutralization is applied to the MHP filtrate to produce a scavenger precipitate and a scavenger filtrate.

[0092] For example, as shown in the flowsheet 200 (FIG. 2), the MHP filtrate 224 is subject to scavenger precipitation 240 using a third neutralizing agent. In this example, the neutralizing agent is lime, e.g., Ca(OH)2. The result is then a scavenger slurry 226.

[0093] In some examples, the scavenger precipitation 240 is performed with a residence time of at least about 2 hours, and more preferably, at least about 3 hours. The precipitation may be performed within a temperature range of about 40°C to 70°C and more preferably, between about 50°C and 60°C. The neutralization agent (e.g., Ca(OH)2) added may be at least about 70% of the stoichiometric amount, and preferably, about 130% of the stoichiometric amount. The neutralization can achieve a pH of at least about 8, and preferably a pH of about 9.25.

[0094] Equations (15) - (16) provide the reactions, which may occur during the scavenger precipitation 240:NiSO4+ Ca(OH)2+ 2 H2O Ni(0H)2+ CaSO4«2H2O (15)

[0095] The scavenger precipitation 240 is therefore used to precipitate further nickel and cobalt hydroxides that were not fully precipitated in the original MHP precipitation 214. In at least one example, the scavenger precipitation occurs at temperature of at least 50°C to maximize nickel and cobalt recovery.

[0096] As further shown in flowsheet 200 (FIG. 2), the scavenger slurry 226 is subjected to soli d / li quid separation 228 to separate a scavenger filtrate 230 from the scavenger precipitate 232 (i.e., the residue recycle 232).

[0097] At 104b (FIG. IB), the scavenger precipitate 232 is recycled and subject to further releaching 206 to produce a re-leach slurry 208 for further recovery of nickel and cobalt.- 14 -WSLEGAL\097549\00002\41667351v6

[0098] In some examples, the re-leaching 206 uses residual hydrated lime from the scavenger precipitation for neutralizing the free acid contained in the autoclave discharge POX slurry 204. Accordingly, the re-leaching can allow for further recovery of nickel and cobalt metals as the flowsheet 200 continues to iterate.

[0099] (Hi. ) Effluent Treatment

[0100] As exemplified in the flowsheet 200 (FIG. 2), in some examples, the residue precipitate246, from the leaching / re-leaching 206, is further processed into tailings 218.

[0101] As shown, effluent treatment 292 can be applied to both the residue precipitate 246 and / or the scavenger filtrate (barren solution) 230. This treatment involves removal of soluble metals from the scavenger filtrate 230 in the presence of washed residue 246.

[0102] In some examples, the solution fed into the effluent treatment 292 contains magnesium sulphate, which can be reacted with a quaternary neutralizing agent, e.g., Ca(OH)2, in a quaternary neutralization to precipitate magnesium hydroxide according to the following chemical reaction expressed in Equation (17):

[0103] In some examples, Ca(OH)2is used to eliminate Na in the aqueous effluent and minimizing the process costs. More generally, this precipitate slurry combined with the solid residue 246 - obtained from primary neutralization stage - may then be directed to a tailing's facility 218. In some examples, a stable solid tailing is produced comprising primarily of magnetite and hematite iron minerals. In some examples, the effluent treatment is performed with a residence time of at least about 2 hours, and more preferably, at least about 3 hours. The treatment may be performed within a temperature range of about 40°C to 70°C and more preferably, between about 50°C and 60°C. The neutralization agent (e.g., Ca(OH)2) added may be at least about 90% of the stoichiometric amount, and preferably, about 120% of the stoichiometric amount, to reach a pH in between about 9.5 and 11.5, and more preferably, a pH in between about 10.5 to 11.5.- 15 -WSLEGAL\097549\00002\41667351v6III. EXAMPLE "A" - PROCESSES FOR PRODUCING ADDITIONAL PRODUCTS FROM MHP PRODUCT

[0104] FIG. 1C shows an example process 100c for further processing MHP product to produce one or more of cobalt product, nickel sulphate crystal products.

[0105] As shown, 102c, the MHP product - produced in the method 100a (FIG. 1A) - is leached to form a second pregnant leach slurry. Solid / liquid separation is then applied to separate the solids from a second pregnant leach solution (SPLS).

[0106] At 104c, impurity extraction (e.g., solvent extraction) is applied to the SPLS to produce an impurity raffinate and an impurity strip solution.

[0107] The purpose of the impurity extraction step is to separate nickel from the SPLS into the impurity raffinate solution. In some examples, producing the impurity raffinate solution involves an iterative combination of impurity extraction followed by nickel scrubbing, such as to ensure that as much nickel is isolated in the raffinate solution.

[0108] At 106c, the impurity strip solution is processed to produce a cobalt hydroxide product.

[0109] At 108c, the impurity raffinate solution is processed using a nickel extraction step, which produces a nickel-rich strip solution as well as a nickel raffinate solution.

[0110] At 110c, the nickel -rich strip solution is processed to produce hydrated nickel sulphate crystal product.

[0111] At 112c, the nickel raffinate is also further processed to produce sodium sulphate crystal biproduct.

[0112] In view of the foregoing, method 100c provides an efficient process for processing MHP product and producing cobalt hydroxide product, nickel sulphate crystal product and sodium sulphate crystals by-product. The process flowsheet is efficiently structured such that the by-product output of one refinery step (e.g., the impurity raffinate) is not disposed of, but is further processed to produce other products downstream. In some examples, the method further involves using one or more the byproducts produced in method 100c for the manufacture of precursor active cathode materials (pCAM) and active cathode materials (CAM) of LIBs, using processes known in the art.- 16 -WSLEGAL\097549\00002\41667351v6

[0113] FIG. 3 provides a more detailed flowsheet 300 exemplifying the process 100c in greater detail.

[0114] FIGs. 4A - 4C segment different portions of the flowsheet 300 relating to production of each of the cobalt hydroxide product (FIG. 4A), hydrated nickel sulphate crystal product (FIG. 4B) and sodium sulphate crystal product (FIG. 4C). The discussion that follows considers each of FIGs. 4 A - 4C in more detail.

[0115] (i.) Example Process for Producing Cobalt Hydroxide Product

[0116] FIG. 4A is a flowsheet 400a for an example process for producing cobalt hydroxide product from MHP product. Flowsheet 400a corresponds to the combination of acts 102c - 106c in method 100c (FIG. 1C).

[0117] As shown in the flowsheet 400a, leaching is initially performed on the MHP product 222 to form the second pregnant leach slurry 408a (act 102c in FIG. 1C). In this example, the leaching is performed using selective atmospheric leaching 402a. The atmospheric leaching 402a involves mixing: (i) the MHP product 222 produced in flowsheet 200 (FIG. 2), and (ii) a leaching agent 406a (e.g., sulphuric acid). The atmospheric leaching 402a can also be performed in the presence of recycled water 404a to enhance process recovery. In some examples, to increase the efficiency of the flowsheet, the steam is in the form of evaporated and condensed water recycled from downstream processes.

[0118] In at least one example, the conditions for performing the atmospheric leaching 402a are selectively controlled such as to cause nickel and cobalt to extract but limit impurity extraction, when mixed with sulphuric acid. For example, the nickel hydroxide and cobalt hydroxide in the MHP product 222 may react and dissolve, under the correct conditions, with the sulphuric acid 406a to produce nickel sulphate and cobalt sulphate but at least a portion of the impurities, such as iron and aluminum, remains as a precipitate / leach residue.

[0119] In some examples, the atmospheric leaching 402a is performed within a pH range of about 1.0 to 7.0, and more preferably, between about 3.5 and 6.0, or about 4.0. The residence time for the leaching may be at least about 2 hours, and more preferably about 4.5 hours. The temperature conditions range between about 50°C and 85°C, and more preferably about 75°C. The pulp density of- 17 -WSLEGAL\097549\00002\41667351v6MHP product with the sulphuric acid may be greater than about 10 wt%, but more preferably about 30% wt of the total combined weight.

[0120] Continuing with reference to flowsheet 400a (FIG. 4A), solid / liquid separation 410a is applied to the leach SPLS 408a such as to separate the unleached hydroxides from the remaining filtrate, herein referred to as the second pregnant leach solution (SPLS) 412a. The separated unleached hydroxides are recycled to the re-leach step 206.

[0121] With respect to the SPLS 412a, this filtrate may still include solubilized impurities. Accordingly, impurity extraction 414a is applied to the SPLS 412a to separate the impurities and cobalt from any other remaining metals (see act 104c in FIG. 1C).

[0122] In this example, the impurity extraction 414a involves applying a solvent extraction technique in which neutralizing agent, e.g., sodium hydroxide is used to control pH. The organic solvent used in the solvent extraction is recycled from further downstream. In some examples, the impurity extraction is applied to a mixture that includes spent scrub 418a (also produced further downstream) and / or spent scrub 428a from subsequent nickel scrubbing 424a. Mixing the spent scrub 418a, 428a allows for further extraction of any remanent or nickel in the scrub 418a, 428a, thereby providing for a more efficient process.

[0123] Examples of extractants, at 414a, used for the selective separation of metals including Mg, Co, Cu, Mn and Zn over Ni from SPLS include bis (2,4,4 trimethyl pentyl) phosphinic acid (Cyanex™ 272) or bis (2,4,4-trimethylpentyl) phosphonic acid (lonquest™ 290) or D2EHPA (di(2- ethylhexyl)phosphoric acid), which can be used individually or in combination under the certain conditions. Suitable diluents include organic solvents such as kerosene (e.g., Exxsol™ D80).

[0124] Impurity solvent extraction, at 414a, may be performed at room temperature (e.g. , about20°C and 25°C) or elevated temperatures (e.g., between about 30°C and 50°C), with pH between about 5.0 to 6.0, and preferably about 5.5 to 5.8.

[0125] The result of the impurity extraction 414a is then a loaded organic 420a and cobalt / impurity raffinate 422a, which includes solubilized nickel.

[0126] The raffinate 422a is carried downstream for further processing, in flowsheet 400b (FIG. 4B), to produce nickel sulphate crystal product.- 18 -WSLEGAL\097549\00002\41667351v6

[0127] With respect to the remaining loaded organic 420a, this is further processed to produce cobalt product 442a. This further processing to the loaded organic 420a corresponds to act 106c (FIG. 1C).

[0128] In some examples, before any further processing of the loaded organic 420a - nickel scrubbing 424a is applied to the loaded organic 420a to further remove any nickel that was extracted during the impurity extraction 414a. The nickel scrubbing 424a can be applied using a scrubbing agent, e.g., dilute sulphuric acid 498a. The result is a scrubbed loaded organic 426a, which can be processed to strip cobalt and other loaded impurities such as magnesium. In some cases, the spent scrub 428a produced by the nickel scrubbing 424a is returned for further impurity extraction 414a. In some examples, the scrubbing is performed at room temperature (e.g., about 20°C and 25°C) or elevated temperatures (e.g., between about 30°C and 50°C), with a pH of between about 5.0 to 6.0, and preferably about 5.0.

[0129] Once the scrubbed loaded organic 426a is formed, it is then subjected to stripping 432a. The stripping 432a is performed in the presence of a stripping agent, e.g., sulphuric acid 430a. The result of the stripping 432a generates a strip solution 436a and the organic phase 434a, which is then recycled to the impurity extraction stage 414a. In some examples, the stripping is performed at ambient room temperature (e.g., about 20°C and 25°C) or elevated temperatures (e.g., between about 30°C and 50°C), with a pH of between about 1.0 and 2.0, and preferably about 1.2.

[0130] Cobalt hydroxide precipitation (CHP) 438a can be applied to the strip solution 436a using a precipitating agent 440a, e.g., sodium hydroxide 440a. This causes any cobalt in the strip solution 426a to precipitate, e.g., as cobalt hydroxide. In this manner, a CHP slurry 446a is formed that contains precipitated cobalt hydroxide. In some examples, the CHP 438a is applied within a pH range of about 6.0 to 7.0, and more preferably about 6.75. The reaction time may be at least about 2 hours, and more preferably about 4 hours. The temperature range may be between about 50°C and 70°C, and more preferably about 60°C.

[0131] Liquid / solid separation 444a is applied to separate the cobalt hydroxide precipitate from the slurry 446a, which then forms the final cobalt hydroxide product 442a. The remaining filtrate 490a, from the liquid / solid separation 444a, is used downstream in method 400c.- 19 -WSLEGAL\097549\00002\41667351v6

[0132] (ii.) Example Process for Producing Nickel Sulphate Crystal Product

[0133] FIG. 4B is flowsheet 400b for an example process for producing nickel sulphate crystal product. As explained, the nickel sulphate crystal product is produced from the impurity / cobalt raffinate 422a produced during the impurity extraction 414a (FIG. 4 A). Flowsheet 400b corresponds to the combination of acts 108c - 110c, in method 100c (FIG. 1C).

[0134] As shown, the cobalt raffinate 422a is initially subject to nickel extraction 402b. The purpose of the nickel extraction 402b is to recover solubilized nickel in the raffinate 422a, which results from the impurity extraction 414a and nickel scrubbing 424a (FIG. 4 A).

[0135] The nickel extraction 402b produces a nickel-loaded organic 404b, that is rich in dissolved nickel. As provided herein, the nickel-loaded organic 404b is processed to produce the desired nickel sulphate crystal product.

[0136] The nickel extraction 402b also produces further nickel raffinate 406b. In some examples, the nickel raffinate 406b is processed downstream in flowsheet 400c (FIG. 4C) to make sodium sulphate crystal product.

[0137] In at least one example, nickel extraction 402b involves a solvent extraction process. This involves mixing the impurity / cobalt raffinate 422a with organic solvent. The organic solvent is recycled organic solvent 416b, that is reused from further downstream in the process during the nickel stripping 412b.

[0138] Examples of extractants suitable for nickel extraction, at 402b, from impurity raffinate include highly branched CIO tertiary carboxylic acid / neodecanoic acid (Versatic™ 10), 5,8-diethyl- 7-hydroxydodecan-6-one oxime (LIX 63), bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex™ 272), and bis(2,4,4-trimethylpentyl) phosphonic acid (lonquest™ 290), which can be used individually or in combination. Examples of the diluent are organic phase diluents, include for instance kerosene, e.g., Exxsol™ D80 or ShellSol™ Dx where x=70, 80, or 90.

[0139] Nickel solvent extraction (NiSX) may be carried out at room temperature (about 20°C to 25°C) or at elevated temperatures (about 30°C to 50°C), with pH adjustment between about 6.0 to 7.0, and more preferably 6.5 to 7.0.- 20 -WSLEGAL\097549\00002\41667351v6

[0140] Continuing with reference to flowsheet 400b, the nickel-loaded organic 404b is subjected to impurity scrubbing 406b. The purpose of the impurity scrubbing 406b is to remove other metal impurities (i.e., aside from nickel) that may still reside in the organic solvent in the nickel-loaded organic 404b. In some examples, the impurity scrubbing 406b is performed by mixing the nickel- loaded organic 420a with a scrub feed solution 407b. In some examples, the scrub feed solution 407b is produced from the Ni pregnant strip solution by adjusting Ni content and pH. The result of the impurity scrubbing 406b is then a scrubbed loaded organic 408b, as well as spent scrub 418a. In some cases, the spent scrub 418a is recycled and used during the impurity extraction 414a (FIG. 4A).

[0141] In some examples, the scrubbing 406b is carried out at room temperature (about 20°C to 25°C) or at elevated temperatures (30°C to 50°C), with pH adjustment between about 5.0 to 6.0, and more preferably 5.8 to 6.0.

[0142] Nickel stripping 412b is subsequently applied to the scrubbed loaded organic 408b. The purpose of the nickel stripping 412b is to isolate out the nickel in the organic solvent, in the scrubbed extract solution 408b. The stripping agent 410b used can be sulphuric acid 410b. The result of the nickel stripping 412b is a nickel sulphate solution product 414b. The separated organic solvent 416b is also formed and is reused during the nickel extraction 402b as explained previously.

[0143] In some examples, the stripping 412b is carried out at room temperature (about 20°C to 25°C) or at elevated temperatures (30°C to 50°C), with pH adjustment between about 2.0 to 3.5, and more preferably around 2.7.

[0144] Once the nickel sulphate solution product 414b is formed, it is crystallized via nickel sulphate crystallization 418b. The crystallization process can involve, for instance, an evaporation followed by cooling process. The result of the crystallization is then a crystallization slurry 420b that includes a mix of nickel sulphate crystals and mother liquor solution. The crystallization process also results in evaporated water 404a. In some examples, the evaporated water 404a is condensed and recycled back for use in the atmospheric leaching 402a of MHP (FIG. 4A).

[0145] In some examples, the crystallization is performed using nickel pregnant strip solutions using a pH of between about 3.5 and 4.5, and more preferably, about 4.0.- 21 -WSLEGAL\097549\00002\41667351v6

[0146] Solid / liquid separation 424b is applied to the crystallization slurry 420b to separate the hydrated nickel sulphate crystal product 426b from the mother liquor filtrate 428b. In at least one example, the mother liquor filtrate 428b is recycled back into the nickel sulphate crystallization 418b to further crystallize any uncrystallized solute. Some of the mother liquor filtrate 428b can also be used during the impurity extraction 414a (FIG. 4 A).

[0147] In view of the foregoing, the flowsheet 400b provides a process for synthesizing nickel sulphate crystal product using the biproduct cobalt raffinate 422a from flowsheet 400a. The nickel sulphate crystal product has widespread applications, including in the production of pCAM for nickel- based LIBs.

[0148] (Hi. ) Example Process for Producing Sodium Sulphate Crystal Product

[0149] FIG. 4C is flowsheet 400c for an example process for production of sodium sulphate crystal product. As explained, sodium sulphate crystal product is produced from the nickel raffinate 406b byproduct produced during the nickel extraction 402b (FIG. 4B). Flowsheet 400c corresponds to acts 112c in method 100c (FIG. 1C).

[0150] As shown, the nickel raffinate 406b is subject to magnesium precipitation 402c using a precipitating agent 404c, e.g., sodium hydroxide. The magnesium precipitation 402c may also be applied to the filtrate 490a, from the solid / liquid precipitation 444a (FIG. 4A). The result is a magnesium hydroxide slurry 408c that includes magnesium hydroxide precipitate and filtrate.

[0151] Solid / liquid separation 410c is applied to the slurry 408c such that the solid magnesium hydroxide precipitate is disposed of, e.g., in a tailing facility. The combination of magnesium precipitation 402c and the solid / liquid separation 410c, accordingly, is to remove magnesium impurities from the nickel raffinate 406b.

[0152] Filtrate 414c, remaining after solid / liquid separation 410c, is then processed to produce the sodium sulphate product. As shown, this process involves applying sodium sulphate crystallization 420c. This produces a crystallization slurry that includes sodium sulphate crystal product and a mother liquor solution. The crystallization process can also result in evaporated water 404a. In some examples, the evaporated water 404a is recycled back into the atmospheric leaching 402a (FIG. 4A).- 22 -WSLEGAL\097549\00002\41667351v6

[0153] Solid / liquid separation 424c is applied to the crystallization slurry 422c to separate the sodium sulphate crystal product 428c from the mother liquor filtrate 426c. In some examples, the mother liquor filtrate 428c is recycled back into the sodium sulphate crystallization 420c to further crystallize any uncrystallized solute.IV. EXAMPLE "B" - PROCESSES FOR PRODUCING PRODUCTS FROM MHP PRODUCT

[0154] FIG. ID shows another example process lOOd for further processing MHP product to produce one or more of cobalt hydroxide product, hydrated nickel sulphate crystal product and / or sodium sulphate crystal product.

[0155] At 102d, the MHP product - produced in the method 100a (FIG. 1A) - is leached to form a second pregnant leach solution (SPLS). This is similar to act 102c in FIG. 1C.

[0156] At 104d, impurity extraction (e.g., solvent extraction) is applied to the SPLS with a nickel preloaded organic to produce an impurity raffinate and an impurity rich strip solution.

[0157] At 106d, crystallization is applied to the impurity raffinate to produce hydrated nickel sulphate crystal product.

[0158] At 108d, cobalt hydroxide precipitation is applied to the impurity rich strip solution to produce cobalt hydroxide product and CHP filtrate.

[0159] At 1 lOd, magnesium precipitation is applied to the CHP filtrate and a nickel raffinate to produce a magnesium hydroxide slurry. After applying solid / liquid separation to the slurry, at 112d, the filtrate is crystallized to produce sodium sulphate crystal product.

[0160] In some examples, the method further involves using one or more the byproducts produced in method lOOd for the manufacture of any intermediate products, such as pCAM used in LIBs, using processes known in the art.

[0161] FIG. 5 provides a more detailed flowsheet 500 exemplifying the process lOOd in greater detail.- 23 -WSLEGAL\097549\00002\41667351v6

[0162] FIGs. 6A - 6C segment different portions of the flowsheet 500 relating more specifically to production of each of cobalt hydroxide product (FIG. 6A), hydrated nickel sulphate crystal product (FIG. 6B) and sodium sulphate crystal product (FIG. 6C). The discussion that follows considers each of FIGs. 6A - 6C in more detail.

[0163] (i.) Example Process for Producing Cobalt Hydroxide Product

[0164] FIG. 6A is a flowsheet 600a for an example process for producing cobalt hydroxide product from the MHP product. Flowsheet 600a corresponds to the combination of acts 102d - 108d in method lOOd (FIG. ID).

[0165] As shown, atmospheric leaching 602a is initially performed, similar to the atmospheric leaching 402a (FIG. 4A). The atmospheric leaching 602a involves mixing the MHP product 222 with a leach solution 604a (e.g., sulphuric acid) and water 606a. In some cases, the water 606a is recycled from downstream processes. The atmospheric leaching also involves mixing nickel precipitate 608a, which is generated further downstream.

[0166] Analogous to the atmospheric leaching 402a (FIG. 4 A), the conditions for performing the atmospheric leaching 602a can be selectively controlled to cause nickel and cobalt to extract, but limit at least one impurity (e.g., iron and aluminum) to extraction, when mixed with the sulphuric acid.

[0167] The product from the atmospheric leaching 602a is a second pregnant leach slurry 610a. Solid / liquid separation 612a is applied to the slurry 610a to separate the unleached hydroxides 442a from a SPLS 614a.

[0168] Impurity extraction 616a is then applied to the SPLS 614a. In some examples, the impurity extraction involves using solvent extraction, whereby nickel preloaded organic solvent 618a is recycled from downstream in the process, i.e., nickel preloading 652a. The impurity extraction 616a is used to isolate dissolved nickel from the remaining dissolved metals in the SPLS 614a. The use of nickel preloading organic for extracting impurities helps to minimize sodium in the impurity raffinate.

[0169] The result of the impurity extraction 616a is loaded organic 622a and impurity raffinate620a. The impurity raffinate 620a is used downstream, in flowsheet 600b, to produce hydrated nickel sulphate crystal product.- 24 -WSLEGAL\097549\00002\41667351v6

[0170] Nickel scrubbing 624a is applied to the loaded organic 622a using a scrubbing agent 626a, e.g., dilute sulphuric acid. This, in turn, results in a scrub loaded organic 630a, as well as spent scrub 628a.

[0171] Impurity stripping 632a is subsequently applied to the scrub loaded organic 630a and using a stripping agent 634a, e.g., sulphuric acid. This results in a pregnant strip solution 636a and a stripped organic 650a.

[0172] The strip solution 636a is subject to cobalt hydroxide precipitation 640a using a precipitating agent 642a, e.g., sodium hydroxide. Solid-liquid separation 646a is applied to the CHP slurry 644a to separate the precipitate comprising cobalt hydroxide product 442a from CHP filtrate 648a. In some examples, the CHP filtrate 648a is sent further downstream for use in flowsheet 600c (FIG. 6C), for producing sodium sulphate crystal product.

[0173] In contrast to the stripped organic 650a produced by the impurity stripping 632a is subject to nickel preloading 652a. The nickel preloading 652a can involve further mixing nickel sulphate solution 654a and sodium hydroxide solution 656a. In some examples, the use of nickel preloading organic for extracting impurities such as Co, Al, Mg, Cu, Mn, and Zn, helps to minimize sodium in the impurity raffinate, which can be used to crystalize nickel sulphate. The output of the nickel preloading 652a is a nickel preloaded organic 618a and nickel preloaded raffinate 658a.

[0174] Nickel precipitation 660a is then applied to the nickel preloaded raffinate 658a, with sodium hydroxide 680a. In some cases, the nickel precipitation 660a is also applied to a mixture of mother liquor filtrate 610b which may include residue nickel, and which is received from the flowsheet 600b, i.e., during crystallization of hydrated nickel sulphate crystal product.

[0175] The output of the nickel precipitation 660a is then a slurry 662a. Solid / liquid separation 664a is performed to separate the nickel precipitate 608a from the filtrate 666a. The nickel precipitate 608a may be recycled to the atmospheric leaching 602a. In some examples, the filtrate 666a is used downstream in flowsheet 600c, for sodium sulphate crystals production.- 25 -WSLEGAL\097549\00002\41667351v6

[0176] (ii.) Example Process for Producing Hydrated Nickel Sulphate Crystal Product

[0177] FIG. 6B is a flowsheet 600b for an example process for producing hydrated nickel sulphate crystal product from MHP product. Flowsheet 600b corresponds to act 108d in method lOOd (FIG. ID).

[0178] As shown, impurity raffinate byproduct 620a - resulting from the impurity extraction 616a (FIG. 6A) - is subject to nickel sulphate crystallization 602b. This produces a crystallized slurry 604b, as well as evaporated water 606a. The evaporated water 604a can be condensed and recycled to the atmospheric leaching 602a (FIG. 6A).

[0179] The crystallized slurry 604b is then further subject to solid / liquid separation 606b to separate hydrated nickel sulphate crystal product 608b from filtrate 610b. In some cases, the filtrate 610b is recycled to the crystallization 602b to crystallize any residue nickel sulphate. In some cases, some of the filtrate 610b can bleed back into the nickel precipitation 660a (FIG. 6A).

[0180] (Hi.) Example Process for Producing Sodium Sulphate Product

[0181] FIG. 6C is a flowsheet 600c for an example process for producing sodium sulphate crystal product from MHP product. Flowsheet 600c corresponds to act 114d in method lOOd (FIG. ID).

[0182] As shown, magnesium precipitation 602c is applied to the mixture of filtrate 666a from the solid / liquid separation 664a (FIG. 6A), as well as a precipitating agent, e.g., sodium hydroxide 604c and CHP filtrate 648a. The resulting magnesium hydroxide slurry 660c is then subject to further solid / liquid separation 608c to separate filtrate 610c from the precipitate. The solid magnesium hydroxide precipitate may be disposed of in a tailing facility.

[0183] Sodium sulphate crystallization 612c may then be performed using the filtrate 610c, as well as the MHP filtrate 648a from the solid / liquid separation 646a (FIG. 6A). The result is a crystallization slurry 614c, as well as evaporated water 606a. The evaporated water can be recycled for use in the atmospheric leaching 602a (FIG. 6A).- 26 -WSLEGAL\097549\00002\41667351v6

[0184] Solid / liquid separation 616c is then performed to the crystallization slurry 614c to separate the sodium sulphate crystal product 418b from the filtrate 618c. The filtrate 618c can be returned for further crystallization at 612c.V. EXAMPLE "C" - PROCESSES FOR PRODUCING PRODUCTS FROM MHP PRODUCT

[0185] FIG. IE shows another example process lOOe for further processing MHP product to produce one or more of cobalt sulphate crystal product, nickel sulphate crystal product and / or sodium sulphate crystal product. The same process produced nickel sulphate and cobalt sulphate product solutions can also be directly used for pCAM synthesis.

[0186] At 102e, the MHP product is leached to produce the second pregnant leach solution (SPLS). At 106e, impurity extraction is applied to SPLS to produce an impurity raffinate and an impurity rich strip solution. At 108e, cobalt and magnesium extraction is applied to the impurity raffinate to produce cobalt raffinate and loaded organic.

[0187] At 11 Oe, crystallization is applied to cobalt raffinate to produce a nickel sulphate crystal product or pCAM synthesis is applied to cobalt raffinate.

[0188] At 112e, cobalt stripping is applied to the loaded organic to produce cobalt sulphate strip solution. At 114e, crystallization may be applied to the cobalt strip solution or pCAM synthesis may be applied to the cobalt strip solution.

[0189] At 116e, nickel preloading is applied to the cobalt raffinate to generate preloaded raffinate. At 118e, residual nickel and cobalt precipitation is applied to a mixed aqueous stream consisting of Ni preloaded raffinate, bleed solution and spent scrub to produce cobalt and nickel hydroxide precipitate and liquid filtrate. At 119e, magnesium is precipitated from liquid filtrate obtained from 118e to precipitate magnesium and to produce a filtrate. At 120e, crystallization is applied to the filtrate from 119e to produce sodium sulphate crystal product.

[0190] In some examples, the method further involves using one or more the byproducts produced in method lOOe for the manufacture of pCAM and CAM from LIBs, using processes known in the art.- 27 -WSLEGAL\097549\00002\41667351v6

[0191] FIG. 7 provides a more detailed flowsheet 700 exemplifying the process lOOe in greater detail.

[0192] FIGs. 8 A - 8D segment different portions of the flowsheet 700 relating more specifically to production of impurity raffinate (FIG. 8A), cobalt sulphate crystal product (FIG. 8B), nickel sulphate crystal product (FIG. 8C) and sodium sulphate crystal product (FIG. 8D). The discussion that follows considers each of FIGs. 8A - 8D in more detail. The steps of these flowsheets are generally similar to that shown in flowsheets 400a - 400c of FIGs. 4A - 4C (as shown by the common numerals), except where indicated otherwise.

[0193] As exemplified in these flowsheets, various appreciated advantages of this process include: (i) production of higher-purity, battery-grade cobalt sulphate instead of lower-grade cobalt hydroxide; (ii) providing for reduced sodium, magnesium and calcium content in a Co raffinate; (iii) increased nickel concentration in a Co raffinate; and (iv) production of battery -grade nickel sulphate solution and crystals suitable for pCAM synthesis without introducing nickel solvent extraction steps.

[0194] (i.) Example Process for Producing Impurity Raffinate

[0195] FIG. 8 A shows a flowsheet 800a for producing an impurity raffinate 422a from the MHP product. Flowsheet 800a corresponds to the combination of acts 102e - 108e in method lOOe (FIG. IE).

[0196] As shown, the process initially includes atmospheric leaching 402a which involves mixing: (i) the MHP product 222 produced in flowsheet 200 (FIG. 2), (ii) a leaching agent 406a (e.g., sulphuric acid), evaporated water / process water 404a, as well as cobalt and nickel hydroxide 848. The result of the leaching is the second pregnant leach slurry (SLPS) 408a. The SLPS 408a is then processed along similar steps as in flowsheet 400a, and produces the impurity raffinate 422a, a filtrate 490a and an impurity precipitate 804.

[0197] (ii.) Example Process for Producing Cobalt Sulphate Crystal Product

[0198] FIG. 8B shows a flowsheet 800b for producing cobalt sulphate crystal product. Flowsheet 800b corresponds to act 112e in method lOOe (FIG. IE).

[0199] As shown, the impurity raffinate 422a undergoes cobalt and magnesium solvent extraction at 806 using a nickel preloaded organic 822, to produce a cobalt raffinate 806a and a cobalt- 28 -WSLEGAL\097549\00002\41667351v6and magnesium loaded organic 808. In some examples, the extraction occurs at a pH between about 5.0 and 6.0, and more preferably, about 5.2 to 5.8.

[0200] The cobalt and magnesium loaded organic 808 is then subjected to magnesium and nickel scrubbing 810 with a scrub solution 407b (e.g., cobalt sulphate solution), resulting in a spent scrub 418a and a scrubbed loaded organic 812. In some cases, the scrub solution was at a pH between 4.0 and 5.0, and more preferably, 4.5 to 4.75.

[0201] The scrubbed loaded organic 812 is mixed with sulphuric acid 410b for cobalt stripping 814, leading to the production of a cobalt strip solution 816 as well as the stripped organic 818. In some examples, the stripping occurs at a pH of between about 0.1 and 3.5, and more preferably 2.5. The organic 818, in presence of sodium hydroxide 410b, is used for nickel preloading with cobalt raffinate 806a, which produces the nickel preloaded organic 821 and a preloaded raffinate 822. In some cases, the nickel preloading 820 is performed at a pH range at about 6.0.

[0202] The final step involves cobalt sulphate crystallization 824, which results in a crystallization slurry 826, and whereby the slurry is separated at 828 into liquid and solid phases, yielding the final solid cobalt sulphate crystal product 832. The remaining liquid forms a filtrate that is reused at the crystallization 824 and a bleed passed downstream.

[0203] (Hi. ) Example Process for Producing Nickel Sulphate Crystal Product

[0204] FIG. 8C shows a flowsheet 800c for producing nickel sulphate crystal product. Flowsheet 800c corresponds to the act 1 lOe, 114e and 118e in method lOOe (FIG. IE).

[0205] As shown, the cobalt raffinate 806a along with the cobalt strip solution enter the pCAM synthesis step 834 to produce pCAM for LIBs production.

[0206] The cobalt raffinate 806a is also used for nickel sulphate crystallization 836, which produces the crystallization slurry 837. The slurry is separated into solid and liquid phases at 838. The solid phase is collected as nickel sulphate crystals 840. The liquid phase is directed back to the crystallization step 836, as well as being used in the nickel and cobalt precipitation 844.

[0207] Nickel and cobalt precipitation 844 is performed from the raffinate 822 from the nickel preloading 820, with the addition of sodium hydroxide 846, as well as process streams from various- 29 -WSLEGAL\097549\00002\41667351v6steps as shown. This step produces (after solid / liquid separation, which is not shown) an aqueous stream 860 used downstream, and a cobalt and nickel hydroxide precipitate product 848. Cobalt and nickel hydroxide precipitate is used to adjust the pH of the SPLS prior to impurity solvent extraction and is recycled to the leaching step.

[0208] (iv.) Example Process for Producing Sodium Sulphate Crystal Product

[0209] FIG. 8D shows a flowsheet 800d for producing sodium sulphate crystal product. Flowsheet 800d is generally analogous to flowsheet 400c (FIG. 4C), as shown. Flowsheet 800d corresponds to acts 119e and 120e in method lOOe (FIG. IE).VI. EXAMPLE TEST RESULTS

[0210] The following examples are intended solely to illustrate aspects or features associated with the described invention, and not to limit any claimed invention.

[0211] Example 1 - Nickle Concentrate Characterization

[0212] As discussed with respect to the flowsheet 200 (FIG. 2), nickel sulphide concentrates are used to form the POX leach slurries (see also act 102a in FIG. 1 A).

[0213] The nickel sulphide concentrates were sourced from the Dumont Nickel Project located in the Abitibi region of Quebec, Canada. The disseminated nickel sulphide and alloy mineralization is hosted within the dunite subzone of the Dumont Sill; a differentiated, ultramafic sill of komatitic affinity. Pentlandite, heazlewoodite - and to a lesser extent awaruite - were the dominant nickel- bearing minerals present in the ore. Chemical assay results and molar ratios of sum of acid consuming metals ((Ni+Co+As+Mg+Cu+Zn+Cr+Al+Mn) / S) to total sulphur for the nickel sulphide concentrates used in method 100a and flowsheet 200, are shown in Table 1.- 30 -WSLEGAL\097549\00002\41667351v6* Molar (mole / mole) ratio = (Ni+Co+As+Mg+Cu+Zn+Cr+Al+Mn) / STable 1 - Assay results of the nickel sulphide concentrate used to develop the flowsheet

[0214] The nickel concentrate contained a range of minerals comprising of pentlandite ( Fe,Ni)9Ss), heazlewoodite (NisSi), magnetite (FesO4), cobalt pentlandite ((Fe,Co,Ni)9S8), brucite (Mg(OH)2), Lizardite (Mg3Si2Os(OH)4), violarite (FeNi2S4), and various gangue minerals including silicates.

[0215] As shown in Table 1, excluding iron (Fe), the sum of the molar mass of acid consuming metals to total sulphur (S) ratios are higher for Cone 2 (2.96) and Cone 3 (1.34), and lower for Cone 4 (0.30) compared to Cone 1 (0.99) and Cone 5 (0.98), which suggests that Cone 2 and Cone 3 are S deficient and Cone 4 contains excess S.

[0216] As used herein and in the remaining Examples, "Cone 1", "Cone 2", "Conc 3", "Cone 4" and "Cone 5" refer to the sulphide concentrates in Table 1.

[0217] Example 2 - Pressure Oxidation.

[0218] In the flowsheet 200 (FIG. 2), pressure oxidation (POX) is performed at 202 to form the POX slurry 204 (see also act 102a in FIG. 1 A).

[0219] During testing, POX leach tests were carried on different nickel sulphide concentrates shown in Table 1 by varying parameters including, temperature, oxygen overpressure, sulphuric acid addition, feed particle size and residence time. The POX tests were conducted using 2 L Parr titanium autoclaves equipped with necessary equipment under autothermal conditions. Some of the conditions and results of POX tests (POX1 - POX4) on a nickel sulphide Cone 1 (Table 1) are summarized in Table 2. Each of these POX tests was conducted at 690 kPa oxygen overpressure under autothermal conditions.WSLEGAL\097549\00002\41667351v6Table 2 - The POX test conditions and results

[0220] As shown in Table 2, extraction of Ni decreases with increasing temperature and achieved excellent Ni and Co extraction and sulphur oxidation (SOX), reaching 95.4% Ni and 94.9% Co in 2 hours, and 99.2% Ni and 98.9% Co within 4 hours of residence time at 150°C and 690 kPa oxygen overpressure with a sulphuric acid (H2SO4) a discharge free sulphuric acid (H2SO4) of 23.6 g / L in POXl.

[0221] It was found that the increasing oxygen over pressure (>690 kPa) and acid addition (>177 kg / t cone) and decreasing particle size (I<xo <48 pm) of sulphur deficient nickel Cone 1 had a negligible impact on the nickel and cobalt extraction kinetics.

[0222] Two POX tests POX5 and POX6 were conducted with another sulphur deficient nickel Cone 2 (Table 1) at 150°C and 175°C, respectively, at 690 kPa oxygen overpressure to evaluate the effect of temperature on Ni extraction and SOx kinetics. Test conditions and results are summarized in Table 3.Table 3 - Effect of temperature on POX leaching of Cone 2 at 690 kPa oxygen overpressure- 32 -WSLEGAL\097549\00002\41667351v6

[0223] As shown in Table 3, increasing temperature from 150°C (POX5) to 175°C (POX6) had an effect on extraction of Ni, Co and SOX, and observes lower extraction of 60.4% Ni, 43.1% Co and 20.0% SOXat 175°C compared to 99.1% Ni, 94.8% Co and 97.3% SOXat 150°C within 4 hours of residence time (although still successfully extracting these elements). Higher Fe concentration is observed in the leach solution of POX5 (10.3 g / L Fe) compared to POX6 solution (0.4 g / L Fe), resulting in lower free acid (8.1 g / L H2SO4) in the POX5 solution than POX6 solution (17.9 g / L H2SO4).

[0224] Three POX tests POX7, POX8 and POX9 were conducted on three different nickel sulphide concentrates of Cone 3, Cone 4 and Cone 5, respectively, at 150°C and 690 kPa oxygen overpressure for 4 hours of residence time, to evaluate the effect of moral ratios of sum of acid consuming metals to total sulphur ((Ni+Co+As+Mg+Cu+Zn+Cr+Al+Mn) / S) on Ni extraction kinetics. In this estimation, the molar mass of Fe is excluded as assuming Fe reports into the POX leach residue. It is noted that Cone 3 is a blend of 75 wt% Cone 1 and 25 wt% Cone 2, and Cone 5 was prepared by blending of 80 wt% Cone 3 and 20 wt% Cone 4. As seen in Table 1, the moral ratios of these metals to S are 1.34, 0.3 and 0.98 for Cone 3, Cone 4 and Cone 5, respectively, which suggest that Cone 3 is a S deficient nickel feed, while Cone 4 has significant amount of excess S and Cone 5 has balanced S. POX7, POX8 and POX9 were conducted by targeting ~22 g / L free H2SO4 in the final pregnant leach solution. Conditions and results of these POX tests are summarized in Table 4.Table 4 - Effect of molar ratios of (Ni+Co+As+Mg+Cu+Zn+Cr+Al+Mn) / S on Ni extraction kinetics- 33 -WSLEGAL\097549\00002\41667351v6

[0225] As shown in Table 4, excess S in the Cone 4 has a negative effect on the extraction of Ni and Co as well as SOX, which results lower recovery of Ni (76.5 %), Co (84.3%) and SOX(82.7%) in POX8 compared to POX7 and POX9 in which over 97% Ni and -99% Co extraction and over 94.5% SOXare observed within 4 hours of residence time. Furthermore, the results of POX1 to POX9 suggest that the autoclave leach conditions such as 150°C (POX5), 690 kPa oxygen overpressure, 4 hours of residence time and minimum particle size of 48 pm of feed, are suitable for higher extraction of Ni, Co and SOXfrom the nickel sulphide concentrates, which have molar ratios of sum of the acid consuming metals to sulphur (Ni+Co+As+Mg+Cu+Zn+Cr+Al+Mn) / S in between 0.9 to 3.0.

[0226] Example 3 - Impurity Removal.

[0227] In flowsheet 200 (FIG. 2), leaching and impurity removal 206 were performed on thePOX slurry 204 to form a pregnant leach solution (PLS) 208 (see also act 104a in FIG. 1 A).

[0228] An impurity removal test was carried out by varying pH values to evaluate the effect of pH on the removal of impurities such as Fe, Al and Cr from an autoclave discharge slurry obtained from the leaching of Cone 3. The pH adjustment was performed with limestone (CaCOs) at 75°C for 2 hours. Before adjusting pH, the oxidation-reduction potential (ORP) of the slurry was increased to about 600 mV with H2O2 for oxidizing ferrous ions into ferric ions, and the 25 wt% CaCCh slurry was used to reach the target pH values of 3.0, 3.5, 4.0 and 4.5. The holding time for each of these pH values was 30 min, and then slurry sample was taken at these pH values, filtered and analyzed solids and liquids for mass and material balance. The results of the impurity removal test are shown in Table 5.- 34 -WSLEGAL\097549\00002\41667351v6Table 5 - Impurity removal from a POX leach slurry obtained from the leaching of Cone 3

[0229] As seen in Table 5, over 99.8% Fe, -99.0% of Al and Cr can be precipitated in between pH of 3.0 and 4.0, with >0.8% Ni and Co deportment to solids. The recovery for Ni and Co was >99.0%, which suggests that one stage precipitation is sufficient to selectively remove these impurities over Ni and Co from the autoclave discharge slurry.

[0230] Example 4 - Mixed Hydroxide Precipitation.

[0231] In flowsheet 200 (FIG. 2), mixed hydroxide precipitation is applied at step 214 (see also act 106a in FIG. 1 A).

[0232] Mixed hydroxide precipitation (MHP) tests MHP1, MHP2, MHP3 and MHP4 were carried out on the feed solution obtained from impurity removal stage with 90% stoichiometric magnesia (MgO) addition for 2 hours at modest temperature (50°C and 60°C) with and without seeding. Tests MHP1 and MHP3 were conducted without seeding and the products obtained from these two tests were recycled as seeds to MHP2 and MHP4, respectively. In the end of each test, slurry was filtered, solids and liquids were analyzed for mass and materials balance. The conditions and results of these tests are summarized in Table 6 and a photograph of a MHP product is shown in Figure 7A.- 35 -WSLEGAL\097549\00002\41667351v6Table 6 - The conditions and results of mixed hydroxide precipitate tests

[0233] As shown in Table 6, seeding of MHP in the tests MHP2 and MHP4 helps to increase Ni and Co precipitation rates, reaching to about 94% Ni and -99% Co precipitation, and minimizes Mg contents in the final products with aNi+Co grade over 47%. About 3.5 wt.% S and 4.3 wt.% S are observed in MHP2 and MHP4 tests, respectively. Sulphur may present in these products as sulphate suspected to be due to formation of some basic nickel and cobalt sulphate during precipitation.

[0234] Example 5 - Scavenger Precipitation.

[0235] In flowsheet 200 (FIG. 2), scavenger precipitation is applied at step 240 (i.e., method 100b in FIG. IB).

[0236] A scavenger precipitation (SP) test, SP1 was carried out on a filtrate obtained from MHP precipitation stage to recover remaining Ni and Co with calcium hydroxide (Ca(OH)2) at 60°C for 3 hours. Test results are summarized in Table 7, which suggests that over 99.0% of Ni and Co can be precipitated with 130 % stoichiometric Ca(OH)2 addition at a pH of -9.1 within 3.0 hours of residence time. A filtrate assay results showed -14.2 mg / L Ni, <0.3 mg / L Co and 17600 mg / L Mg.The SP solids analyzed about 5.9% Ni, 0.04% Co with 5.7% Mg and -17.7% Ca. It is noted that SP product is recycled to re-leaching stage of the flowsheet to recover these Ni and Co.- 36 -WSLEGAL\097549\00002\41667351v6Table 7 - The assay results of different process streams of scavenger precipitate (SP) test

[0237] Example 6 - Effluent Treatment.

[0238] An effluent treatment (ET) test, ET1 was carried out on a filtrate obtained from SP precipitation stage to remove Mg and other metals with Ca(OH)2 at 50°C for 3 hours. The solids obtained from impurity removal stage (iii) were added as a seed to this test. Test conditions and results are summarized in Table 8, which suggests that most of Mg can be precipitated with 120% stoichiometric lime addition within 3.0 hours of residence time. A filtrate assay results showed -1.89 mg / L Mg, <0.6 mg / L Ni and 702 mg / L Ca. It is noted that ET product slurry will be stored in the tailing management facility.- 37 -WSLEGAL\097549\00002\41667351v6Table 8 - The assay results of different process streams of effluent treatment (ET) test

[0239] Example 7 - POX Leach Solids Residue.

[0240] X-Ray refractory (XRD) analysis was carried out on a POX leach residue obtained from the leaching of nickel Cone 3, to identify the minerals present in residue. The identified minerals are shown in Table 9 and FIG. 10. These XRD results suggest that the POX leaching of the sulphur deficient nickel sulphide concentrate produces a stable solid tailing consisting primarily of magnetite and hematite iron minerals.- 38 -WSLEGAL\097549\00002\41667351v6POX ResidueMineral wt %Hematite 30.4Magnetite 45.9Quartz 5.7Tridymite 4.4Lizardite 3.3Cristobalite 2.4Talc 2.4Pentlandite 1.8Clinoch lore 1.8Pyrrhotite 1.2Manganosite 0.5TOTAL 100Table 9 - Mineralogy of a POX leach residue obtained from the leaching of nickel Cone 3

[0241] Example 8 - Atmospheric Leaching of MHP.

[0242] In flowsheet 300 (FIG. 3) and flowsheet 400a (FIG. 4A), selective atmospheric pressure leaching was performed at step 402a (i.e., method 102c in FIG. 1C) to produce second pregnant leach solution (SPLS) 412a, which was subsequently used to obtain cobalt product 442a and nickel sulphate products 414b and 426b (Flowsheet 400b and Fig. 4B).

[0243] An atmospheric pressure leaching test was performed in a 1 L reactor on MHP product by varying the pH from 7.0 to 1.5 with sulphuric acid solution at about 75 °C for a total residence time of 4.5 hours at a pulp density of about 30 wt. %. The holding time at each pH level was 45 minutes.The oxidation-reduction potential (ORP) ranged between 181 mV and 338 mV, with an average value of 254 mV. The test results are summarized in Tables 10a and 10b.

[0244] As shown in Tables 10a and 10b, excellent selective extraction of Ni and Co was achieved over Al and Fe at about pH 3.0 - 4.0 under these conditions without adding any redox reagents (i.e., hydrogen peroxide (H2O2)).WSLEGAL\097549\00002\41667351v6Table 10a - Atmospheric leaching of MHP with sulphuric acid solution- 40 -WSLEGAL\097549\00002\41667351v6Table 10b - Atmospheric leaching of MHP with sulphuric acid solution

[0245] Example 9 - Impurity Solvent Extraction-I

[0246] In flowsheet 400a (FIG. 4A), impurity extraction 414a is performed on SPLS 412a with an organic phase 434a to produce impurity raffinate 422a and an impurity -loaded organic phase 420a.This loaded organic phase is subsequently used in nickel scrubbing 424a and impurity stripping 432a to produce an impurity strip solution 436a (see also act 104c in FIG. 1C, and flowsheet 300, FIG. 3).

[0247] The SPLS / feed solution was subjected to a four-stage counter-current extraction with an organic phase consisting of 12% v / v Cyanex™ 272 in Exxsol™ D80 at approximately 50°C, with an organic-to-aqueous (O / A) phase ratio of about 1.5: 1 and a contact time of about 3 minutes per stage to produce an impurity loaded organic and an ISX raffinate. The loaded organic was then subjected to a three-stage counter-current scrubbing (3 minutes per stage) and a three-stage stripping (3 minutes per stage) with dilute and concentrate sulphuric acid solutions, respectively, to produce an impurity pregnant strip solution and a metal-depleted organic phase. The advance O / A phase ratios for scrubbing and stripping were about 18: 1 and 28: 1, respectively. The ISX test conditions and results are presented in Tables I la and 1 lb.

[0248] As shown in Tables I la and 1 lb, complete extraction of Co, Mn, Cu and Zn, and nearly all of the Mg, was achieved selectively over Ni at a pH of range of 5.3 - 5.8 under these conditions. More than 99% of co-extracted Ni was scrubbed from the loaded organic phase at around pH 5.0,WSLEGAL\097549\00002\41667351v6resulting in a pregnant strip solution containing approximately 41300 mg / L Co, 29400 mg / L Mg, and other impurities. This stripped organic was recycled to the extraction stage, and the strip liquor was used in the Co recovery step. The ISX raffinate was subsequent used in the Ni solvent extraction process steps.Table 1 la - Impurity solvent extraction (ISX) test resultsTable 1 lb - Impurity solvent extraction (ISX) test results

[0249] Example 10 - Nickel Solvent Extraction.

[0250] In flowsheet 400b (FIG. 4B), nickel extraction 402b is performed on impurity raffinate422a with an organic phase 416b to produce nickel raffinate 406b and a Ni loaded organic phase 404b. This loaded organic phase is subsequently used in impurity scrubbing 406b and nickel stripping 412b steps to generate a nickel strip solution / nickel sulphate solution product 414b (see also act 108c in FIG. 1C, and flowsheet 300, FIG. 3).

[0251] The impurity raffinate was subj ected to a three-step counter-current extraction with an organic phase consisting of 40% v / v Versatic™ 10 in Exxsol™ D80 at about 50°C, with an advance- 42 -WSLEGAL\097549\00002\41667351v6O / A phase ratio of 1.9: 1 for a contact time of 3 minutes per stage to produce a nickel loaded organic phase and a nickel raffinate. The loaded organic was subsequently subjected to three-stage countercurrent scrubbing (3 minutes per stage) and a three-stage stripping (3 minutes per stage) with a 35 g / L Ni-containing sulphate solution and a 200 g / L sulphuric acid solution, respectively, to produce a nickel strip solution and a nickel-depleted organic phase. The advance O / A phase ratios for scrubbing and stripping were about 15: 1 and 5: 1, respectively. Nickel solvent extraction (NiSX) test conditions and results are summarized in Tables 12a and 12b.

[0252] As shown in Tables 12a and 12b, more than 99.9% of Ni can be selectively extracted over Mg at a pH rage of 6.5 - 7.0 under these conditions. Most impurities, including Mg and Ca were scrubbed from the loaded organic phase at about pH 5.8 - 6.0 and produced a very high-purity nickel sulphate solution (>99.99% purity) consisting about 128,000 mg / L Ni and less than 5 mg / L total impurities. This stripped organic was recycled back to the extraction stage, and stripped liquor was used in the nickel sulphate crystallization step. The nickel raffinate can be used in the subsequent sodium sulphate crystallization step.Table 12a - Nickel solvent extraction test resultsTable 12b - Nickel solvent extraction test resultsWSLEGAL\097549\00002\41667351v6

[0253] Example 11 - Nickel Sulphate Crystallization on Nickel Strip Solution.

[0254] In flowsheet 400b (FIG. 4B), nickel sulphate crystallization 418b is performed on the nickel sulphate solution product 414b by evaporative crystallization to produce a hydrated nickel sulphate crystal product 426b and evaporated water 404a (see also act 110c in FIG. 1C, and flowsheet 300, FIG. 3).

[0255] Nickel sulphate crystallization tests were conducted in a 10 L reactor using nickel strip solutions of about pH 4.0 by 40 - 50 % volume reduction through evaporation. The resulting slurry wase cooled to about 40°C and then filtered to recover hydrated nickel sulphate (NiSCh.xH?!)) crystals and filtrate, which can be recycled back to the crystallizer.

[0256] As shown in Tables 13a and 13b, high-purity nickel sulphate hexahydrate(NiSC>4 6H2O) was produced under these conditions, containing 22.3 wt.% Ni and a purity exceeding 99.999%. Most impurities in the NiSC>4 crystal product were below 1 ppm. A photograph of the hydrated nickel sulphate crystals is presented in FIG. 9B.Table 13a - Nickel sulphate crystallization test results on a nickel sulphate strip solution- 44 -WSLEGAL\097549\00002\41667351v6

[0257] Example 12 - Cobalt Hydroxide Precipitation.

[0258] In flowsheet 400a (FIG. 4A), cobalt hydroxide precipitation 438a is performed on impurity strip solution 436a to produce a valuable cobalt hydroxide precipitate by-product 442a and a filtrate 490a (see also flowsheet 300, FIG. 3 and act 106c in FIG. 1C).

[0259] Cobalt hydroxide precipitation tests were carried in a 2 L reactor on an impurity strip solution by varying residence time and pH with a sodium hydroxide solution at 60°C to evaluate the selective cobalt precipitation over magnesium. A precipitation test results are shown in Table 14.

[0260] As shown in Table 14, about 91.5% of cobalt was precipitated at pH 6.75 within 4 hours at 60°C, with minimal co-precipitation of magnesium (less than 0.6%). This process yielded a highgrade cobalt hydroxide product containing 50.7 wt.% Co and about 0.22 wt.% Mg. The remaining -8.5% of cobalt in the filtrate can be further recovered by increasing the pH in a subsequent precipitation step, prior to magnesium precipitation with caustic solution.Table 14 - Cobalt hydroxide precipitation test results on an impurity pregnant strip solution

[0261] Example 13 - Sodium Sulphate Crystallization.

[0262] In flowsheet 400c (FIG. 4C), sodium sulphate crystallization 420c is performed on the magnesium precipitate filtrate 414c via evaporative crystallization to produce hydrated sodium sulphate crystal product 428c and evaporated water 404a (see also act 112c in FIG. 1C and flowsheet 300, FIG. 3).

[0263] Sodium sulphate crystallization tests were carried in a 10 L reactor using the magnesium precipitate filtrate by 70 - 75% volume reduction through evaporation. The resulting slurries were cooled and filtered to recover hydrated sodium sulphate (Na2SO4.xH2O) crystals and- 45 -WSLEGAL\097549\00002\41667351v6filtrates. The filtrates can be recycled back to the crystallizer. A sodium sulphate crystallization test results are shown in Table 15.

[0264] As shown in Table 15, high-purity hydrated sodium sulphate (ISfeSCh.xfhO) product was produced under these conditions, containing approximately 21.4 wt.% Na and a purity exceeding 99.9%. This hydrated sodium sulphate can be further dried to produce an anhydrous sodium sulphateTable 15 - Sodium sulphate crystallization test results.

[0265] Example 14 - Impurity Solvent Extraction - II

[0266] In flowsheet 600a (FIG. 6A), impurity extraction 616a can be performed on SPLS 614a with a nickel loaded organic phase 618a to produce impurity raffinate 620a and an impurity-loaded organic phase 622a. This loaded organic phase can be subsequently used in scrubbing 624a and impurity stripping 632a to produce an impurity strip solution 636a (see also act 104d in FIG. ID, and flowsheet 500, FIG. 5).

[0267] As mentioned earlier, metals such as Mg, Co, Cu, Mn and Zn can be selectively separated over Ni from SPLS with an organic phase consisting of bis (2,4,4 trimethyl pentyl) phosphinic acid (Cyanex™ 272), bis (2,4,4-trimethylpentyl) phosphonic acid (lonquest™ 290) or- 46 -WSLEGAL\097549\00002\41667351v6di(2-ethylhexyl)phosphoric acid (D2EHPA), either individually or in combination, under the certain conditions.

[0268] For example, a Ni-preloaded synergistic extraction system comprising of 8% v / v Cyanex 272 and 8% v / v D2EHPA in Exxsol™ D80 can be used to selectively extract Ca, Co, Cu, Mg, Mn and Zn over Ni from the feed solution (SPLS).

[0269] The use of Ni-preloaded organic for extracting these metals minimizes sodium content in the impurity raffinate. The addition of D2EHPA to Cyanex 272 in organic phase can enhance Ca extraction, as Cyanex 272 alone has very low extraction affinity for Ca.

[0270] Prior to impurity extraction, Ni-preloading can be performed by contacting this synergistic extraction system with a nickel sulphate solution (impurity raffinate) under certain conditions. The resulting impurity raffinate can be used directly for nickel sulphate (NiSCh.xEEO) crystal production, as well as for synthesizing precursor cathode active materials (pCAM) for nickel- manganese-cobalt (NMC) LIBs. In contrast, the loaded organic phase can subsequently be contacted with dilute acid for scrubbing Ni, followed by concentrated acid for stripping the impurity metals.

[0271] Example 15 - Impurity Solvent Extraction-Ill.

[0272] In flowsheet 800a (FIG. 8A), impurity extraction 414a is performed on SPLS with an organic phase to produce an impurity raffinate 422a and an impurity-loaded organic phase 420a. The loaded organic is subsequently subjected to scrubbing and impurity stripping to produce an impurity strip solution.

[0273] The second pregnant leach solution (SPLS) 412a (FIG. 8 A) was subjected to contact with an organic phase consisting of 5% by volume D2EHPA (di(2-ethylhexyl)phosphoric acid) and 1.5% TBP (Tri-butyl phosphate) in Exxsol™ D80 by varying O / A phase ratios of 5: 1, 2: 1, 1 : 1, 1 :2 and 1 : 10 for 3 minutes at 45°C to extract impurities including Ca, Cu, Fe, Mn and Zn and to generate an impurity solvent extraction (ISX) raffinate for subsequent Co and Mg solvent extraction.

[0274] The loaded organic 420a (FIG. 8 A) was subjected to three-stage successive contacts at the O / A phase ratio of 1 :2 with a dilute sulphuric acid solution at pH 2.5, for 3 minutes at 45°C, to scrub co-extracted Co and Ni. The scrubbed organic was contacted with a dilute sulphuric acid solution at pH 1.0 at the O / A phase ratio of 1 : 1, for 3 minutes at 45°C, to strip the impurities. The results of- 47 -WSLEGAL\097549\00002\41667351v6impurity extraction, scrubbing and stripping test results are shown in Tables 16, 17 and 18, respectively.

[0275] As shown in Table 16, most impurities were effectively extracted using 5% v / v D2EHPA, with Ni co-extraction remaining below 0.13% under these conditions. Scrubbing results in Table 17 suggest that most of the co-extracted Co and Ni were successfully scrubbed from the loaded organic at pH 2.5. As presented in Table 18, the impurities were effectively stripped from the scrubbed organic at pH 1.0.Ca Co Cu Fe Mg Mn Ni Zn NaSecond Pregnant Leach Solution, mg / L126 2740 15 0.8 2000 1.0 75000 21Raffinate, mg / L4.2 1770 1.7 < 0.2 879 <0.6 73500 1 597011.5 2490 5 < 0.2 1680 <0.6 76700 1 152022.6 2730 8.5 < 0.2 1910 <0.6 79800 1 70941.7 2810 11 < 0.2 2020 <0.6 79700 1 39967.3 2860 13.4 < 0.2 2050 <0.6 77300 <1 4Loaded organic, mg / L30.9 210.7 4.1 8.1 222.9 1.6 772.0 4.967.2 177.4 5.7 8.1 200.0 1.6 309.4 12.1119.8 157.9 7.3 8.1 183.0 1.6 217.0 24.3201.6 173.3 9.7 8.1 183.0 1.6 200.8 49.4660.0 290.0 21.0 8.2 337.0 3.3 454.0 239.0Extraction, %96.5 36.2 91.9 99.5 54.7 92.8 4.8 95.990.8 12.4 69.2 98.8 19.1 84.2 0.8 96.082.1 5.5 46.2 97.6 8.7 73.0 0.3 96.066.9 3.0 30.6 95.3 4.3 57.4 0.13 96.147.0 1.0 14.0 80.0 1.6 35.0 0.10 96.0Table 16 - Impurity extraction tests results with D2EHPAWSLEGAL\097549\00002\41667351v6Scrubbed-loaded organic, mg / LTable 17 - Impurity scrubbing tests resultsStripped organic, mg / LTable 18 - Impurity stripping results

[0276] Example 16 - Cobalt and Magnesium Solvent Extraction.

[0277] In flowsheet 800b (FIG. 8B), extraction of cobalt and magnesium 806 is performed on an impurity raffinate 422a with a Ni-preloaded organic phase to produce a cobalt-free raffinate 806a for nickel recovery and a Co- and Mg-loaded organic phase 808. This loaded organic is subsequently subjected to magnesium scrubbing 810 and cobalt stripping 814 steps to produce a cobalt strip solution 816 for cobalt sulphate product recovery.

[0278] As mentioned earlier, the metals including Mg, Co, Cu, Mn and Zn can be selectively separated over Ni from SPLS with an organic phase consisting of bis (2,4,4 trimethyl pentyl) phosphinic acid (Cyanex™ 272), bis (2,4,4-trimethylpentyl) phosphonic acid (lonquest™ 290) or D2EHPA (di(2-ethylhexyl)phosphoric acid), either individually or in combination under certain conditions. For an example, a Ni-preloaded synergistic organic phase consisting of 15% v / v Cyanex 272 and 1% v / v lonquest in Exxsol™ D80 was used to selectively extract Co and Mg over Ni from ISX raffinate. The use of Ni-preloaded organic for extracting Co and Mg minimizes sodium content in the cobalt raffinate.- 49 -WSLEGAL\097549\00002\41667351v6

[0279] Prior to Co and Mg extraction 806, Ni-preloading was performed by contacting this organic phase with a nickel sulphate solution (feed solution) at an O / A phase ratio of 5: 1, at 50°C for 3 minutes, and at pH 6.0. The results of the nickel preloading test are shown in Table 19, which suggests that about 5124 mg / L Ni can be preloaded onto the organic phase under these conditions.Table 19 - Nic cel preloading test results with a synergistic organic phase

[0280] The ISX raffinate 422a (FIGs. 8 A, 8B) was subjected to pH adjustment at about 5.8 with a nickel hydroxide slurry prior to cobalt and magnesium extraction. The pH adjusted ISX raffinate was then subjected to three successive contacts with a Ni-preloaded organic phase at an O / A phase ratio of 1 : 1, at 50°C for 3 minutes per contact, without pH control, to extract Co and Mg and generate a raffinate for nickel recovery. The pH was not controlled with caustic solution during the extraction to minimize sodium content in the ISX raffinate.

[0281] The results are shown in Table 20, which suggests that more than 99.5% of cobalt and magnesium can be selectively extracted with this Ni-preloaded organic phase under the given conditions. Furthermore, the resulting high-purity cobalt raffinate 806a (i.e. nickel sulphate solution) can be directly used in the synthesis of precursor cathode active materials (pCAM) for lithium-ion batteries, as well as in the production of hydrated nickel sulphate (i.e., NiSCL 6H2O) crystals.Table 20 - Cobalt and magnesium extraction results with Ni-preloaded organic phase

[0282] A cobalt and magnesium loaded organic phase 808 (FIG. 8B) was subjected to three successive contacts with a cobalt sulphate solution (scrub feed solution) containing of 50,000 mg / LWSLEGAL\097549\00002\41667351v6Co at pH 4.75 - 4.5, for 3 minutes at 50°C, to scrub Mg and Ni from the loaded organic phase. The results are shown in Table 21, which suggests that magnesium and nickel can be selectively scrubbed under these conditions.

[0283] The scrubbed-loaded organic phase 812 was subjected to contact with a concentrated sulphuric solution at the O / A phase ratios of 8: 1 and 15.9: 1, for 3 minutes at 50°C, to strip cobalt from the organic phase.

[0284] The results are shown in Table 22, which suggests that a high-purity cobalt sulphate strip solution with a purity greater than 99.9% can be obtained under these conditions. This high-purity cobalt sulphate solution can be directly used for the synthesis of pCAM for lithium-ion batteries, as well as to produce hydrated cobalt sulphate crystals (CoSO^xkbO).Table 22 - Cobalt stripping tests results.- 51 -WSLEGAL\097549\00002\41667351v6

[0285] Example 17 - Nickel Sulphate Crystallization on Cobalt Raffinate.

[0286] In flowsheet 800c (FIG. 8C), nickel sulphate crystallization 836 is performed on the cobalt raffinate via evaporative crystallization to produce hydrated nickel sulphate crystals and evaporated water.

[0287] Nickel sulphate crystallization test was carried in a 1 L reactor using the cobalt raffinate 806a, with approximately 60% volume reduction through evaporation. The resulting slurry was cooled to about 40°C and filtered to obtain hydrated nickel sulphate (NiSCU’xFhO) crystals and a filtrate, which can be recycled back to the crystallizer.

[0288] As shown in Table 23, high-purity hydrated nickel sulphate (NiSC xFbO) was produced under these conditions, containing 21.9 wt.% Ni and a purity exceeding 99.8%.Ni Al Ca Co Cr Cu Fe K Mg Mn Na ZnSample mg / LCobalt ra 83600 <0.3 3.3 <0.5 0.2 <0.1 <0.2 7 59.5 <0.04 1480 <2NiSO i C.9 wt.% <1.7 7.9 <2.6 <1.7 <0.9 <1.7 <8.7 104.7 <0.3 34.0 <17.5Table 23 - Nickel sulphate crystallization test results on a cobalt raffinateV. INTERPRETATION

[0289] Various systems or methods have been described to provide an example of an embodiment of the claimed subject matter. No embodiment described limits any claimed subject matter and any claimed subject matter may cover methods or systems that differ from those described below. The claimed subject matter is not limited to systems or methods having all of the features of any one system or method described below or to features common to multiple or all of the apparatuses or methods described below. It is possible that a system or method described is not an embodiment that is recited in any claimed subject matter. Any subject matter disclosed in a system or method described that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicants, inventors or owners do- 52 -WSLEGAL\097549\00002\41667351v6not intend to abandon, disclaim or dedicate to the public any such subject matter by its disclosure in this document.

[0290] Furthermore, it will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Also, the description is not to be considered as limiting the scope of the embodiments described herein.

[0291] It should also be noted that the terms “coupled” or “coupling” as used herein can have several different meanings depending in the context in which these terms are used. For example, the terms coupled or coupling may be used to indicate that an element or device can electrically, optically, or wirelessly send data to another element or device as well as receive data from another element or device. As used herein, two or more components are said to be “coupled”, or “connected” where the parts are joined or operate together either directly or indirectly (i.e., through one or more intermediate components), so long as a link occurs. As used herein and in the claims, two or more parts are said to be “directly coupled”, or “directly connected”, where the parts are joined or operate together without intervening intermediate components.

[0292] It should be noted that terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree may also be construed as including a deviation of the modified term if this deviation would not negate the meaning of the term it modifies.

[0293] As used herein, the term “about” is intended to encompass variations of ±20%, ±15%, ±10%, ±5% or ±1% of the recited value, unless the context clearly dictates otherwise.

[0294] Additionally, it should be appreciated that items included in a list in the form of “at least one of A, B, and C” can mean (A); (B); (C); (A and B); (B and C); (A and C); or (A, B, and C).- 53 -WSLEGAL\097549\00002\41667351v6Similarly, items listed in the form of “at least one of A, B, or C” can mean (A); (B); (C); (A and B); (B and C); (A and C); or (A, B, and C).

[0295] Further, with respect to the claims, the use of words and phrases such as “a,” “an,” “at least one,” and / or “at least one portion” should not be interpreted so as to be limiting to only one such element unless specifically stated to the contrary, and the use of phrases such as “at least a portion” and / or “a portion” should be interpreted as encompassing both embodiments including only a portion of such element and embodiments including the entirety of such element unless specifically stated to the contrary.

[0296] Furthermore, any recitation of numerical ranges by endpoints herein includes all numbers and fractions subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, and 5). It is also to be understood that all numbers and fractions thereof are presumed to be modified by the term "about" which means a variation of up to a certain amount of the number to which reference is being made if the end result is not significantly changed.

[0297] In the drawings, some structural or method features may be shown in specific arrangements and / or orderings. However, it should be appreciated that such specific arrangements and / or orderings may not be required. Rather, in some embodiments, such features may be arranged in a different manner and / or order than shown in the illustrative figures unless indicated to the contrary. Additionally, the inclusion of a structural or method feature in a particular figure is not meant to imply that such feature is required in all embodiments and, in some embodiments, may not be included or may be combined with other features.

[0298] It should further be appreciated that although reference to a “preferred” component or feature may indicate the desirability of a particular component or feature with respect to an embodiment, the disclosure is not so limiting with respect to other embodiments, which may omit such a component or feature. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.- 54 -WSLEGAL\097549\00002\41667351v6

[0299] The present invention has been described here by way of example only, while numerous specific details are set forth herein in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that these embodiments may, in some cases, be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the description of the embodiments. Various modification and variations may be made to these exemplary embodiments without departing from the spirit and scope of the invention, which is limited only by the appended claims.- 55 -WSLEGAL\097549\00002\41667351v6

Claims

CLAIMS:

1. A continuous, hydrometallurgical process for producing mixed hydroxide precipitate (MHP) comprising: a. mixing a sulphur deficient nickel sulphide concentrate with sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase; b. primary neutralization of the aqueous phase of the leach slurry with a neutralizing agent for removal of at least one impurity to form a neutralized pregnant leach solution (PLS) having at least one primary metal; and c. secondary neutralization of PLS to precipitate MHP and conducting solid-liquid separation to produce MHP product and MHP filtrate.

2. A continuous, hydrometallurgical process for producing MHP as claimed in claim 1, further comprising blending an excess sulphur containing nickel concentrate or iron sulphide (i.e., pyrite, pyrrhotite) with the sulphur deficient nickel concentrate.

3. A continuous, hydrometallurgical process for producing MHP as claimed in claims 1 or 2, further comprising a tertiary neutralization of the MHP filtrate to produce a scavenger precipitate and a scavenger filtrate.

4. A continuous, hydrometallurgical process for producing MHP as claimed in claims 3, further comprising mixing the scavenger precipitate with the leach slurry for recovery of at the least one primary metal.

5. A continuous, hydrometallurgical process for producing MHP as claimed in claim 3 or 4, further comprising a quaternary neutralization of the scavenger filtrate to produce a solid residue for tailings.

6. A continuous, hydrometallurgical process for producing MHP as claimed in claims 1 or 2, wherein the process precipitates high-grade, very low impurity MHP.- 56 -WSLEGAL\097549\00002\41667351v67. A hydrometallurgical process for producing nickel sulphate product, comprising: a. mixing a sulphur deficient nickel sulphide concentrate with sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase; i. primary neutralization of the aqueous phase of the leach slurry with a neutralizing agent for removal of at least one impurity to form a neutralized pregnant leach solution (PLS) having at least one primary metal; and ii. secondary neutralization of PLS to precipitate MHP and conducting solid-liquid separation to produce MHP product and a MHP filtrate; b. leaching the MHP with sulphuric acid and water to form a second pregnant leach solution (SPLS); c. subjecting the SPLS to impurity extraction to produce an impurity raffinate; and d. nickel extraction from the impurity raffinate to produce a nickel sulphate solution product.

8. A hydrometallurgical process for producing nickel sulphate product as claimed in claim 7, further comprising crystalizing the nickel sulphate solution product to form hydrated nickel sulphate crystals.

9. A hydrometallurgical process for producing nickel sulphate product, comprising: a. mixing a sulphur deficient nickel sulphide concentrate with sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase; i. primary neutralization of the aqueous phase of the leach slurry with a neutralizing agent for removal of at least one impurity to form a neutralized pregnant leach solution (PLS) having at least one primary metal; and- 57 -WSLEGAL\097549\00002\41667351v6ii. secondary neutralization of PLS to precipitate MHP and solid - liquid separation to produce MHP product and a MHP filtrate; b. leaching the MHP with sulphuric acid and water to form a second pregnant leach solution (SPLS); and c. subjecting the SPLS to impurity extraction to produce an impurity raffinate to yield a nickel sulphate solution product.

10. A hydrometallurgical process for producing nickel sulphate product as claimed in claim 9, further comprising crystalizing the impurity raffinate to form hydrated nickel sulphate crystals.

11. A hydrometallurgical process for producing nickel sulphate product as claimed in any one of claims 7 to 10, wherein the process further comprises a tertiary neutralization of the MHP filtrate to produce a scavenger precipitate and a scavenger filtrate.

12. A hydrometallurgical process for producing nickel product as claimed in claim 11, wherein the process further comprises a quaternary neutralization of the scavenger precipitate filtrate to produce a tailing.

13. A hydrometallurgical process for producing nickel product as claimed in any one of claims 7 to 10, further comprising blending an excess sulphur containing nickel concentrate or iron sulphide (i.e., pyrite, pyrrhotite) with the sulphur deficient nickel concentrate.

14. The process as claimed in any one of claims 1 to 13, wherein the sulphur deficient nickel sulphide concentrate has a particle size of less than 80 pm, more specifically in between 40 pm and 80 pm.

15. The process as claimed in any one of claim 1 to 14, wherein the nickel sulphide concentrate has molar ratio of sum of the acid consuming metals (Ni+Co+Al+As+Mg+Mn+Cr+Cu+Zn) to total sulphur in the range of 0.8 to 3.0.- 58 -WSLEGAL\097549\00002\41667351v616. The process as claimed in any one of claim 1 to 15, wherein the mixing occurs at a minimum temperature of 140°C.

17. The process as claimed in any one of claims 1 to 16, wherein the mixing occurs at an oxygen partial pressure of between 600 to 750 kPa, preferably in between 650 to 750 kPa and more preferably 690 kPa.

18. The process as claimed in any one of claim 1 to 17, wherein the leaching occurs over a residence time of at least 2 hours.

19. The process as claimed in any one of claim 1 to 18, wherein the total sulphur oxidation occurs in the range of about 95% to 99%.

20. The process as claimed in any one of claim 1 to 19, wherein the MHP recovers >97.0% nickel and cobalt respectively.

21. The process as claimed in any one of claim 7 to 20, wherein the nickel hydroxide recovers >97.0% nickel.

22. A continuous, hydrometallurgical process for producing mixed hydroxide precipitate (MHP) comprising: mixing a sulphur deficient nickel sulphide concentrate with sulphuric acid, water and oxygen to form a leach slurry having an aqueous phase, wherein the mixing the sulphur deficient nickel sulphide concentrate has a particle size of greater than 48 pm occurs at a minimum temperature of 140°C, at an oxygen partial pressure of between 600 to 750 kPa, preferably in between 650 to 750 kPa and more preferably 690 kPa, over a residence time of 2 to 4 hours and the consumption of sulphuric acid is no greater than 1,100 kg / t sulphide concentrate.- 59 -WSLEGAL\097549\00002\41667351v623. The process as claimed in any one of claims 1 to 23, wherein the leaching of the sulphur deficient nickel sulphide concentrate produces a stable solid tailings consisting primarily of magnetite and hematite iron minerals mixed with gypsum.

24. The process as claimed in any one of claims 1, 7, 9 or 22, further comprising about 99% leach recovery of Ni and Co from MHP at a pH between 3.0 and 4.0 with a sulphuric acid solution, without the addition of any redox reagents such as hydrogen peroxide (H2O2), under atmospheric pressure and elevated temperature to produce secondary pregnant leach solution (SPLS).

25. The process as claimed in any one of claims 1, 7, 9 or 22, further comprising production of an impurity / cobalt raffinate comprising nickel sulphate solution with a high nickel concentration of more than 80 g / L, and low impurity levels comprising <5 mg / L Ca, <12 mg / L Mg and <700 mg / L Na, without any nickel solvent extraction.

26. The process as claimed in claim 25, wherein the nickel sulphate solution is used directly for pCAM synthesis or crystallization to produce hydrated nickel sulphate crystals with a purity exceeding 99.8%.- 60 -WSLEGAL\097549\00002\41667351v6

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