Ferronickel alloy direct refining process and nickel sulfate or other nickel product manufacturing process

Abstract

Processes and methods for refining ferronickel alloys and producing nickel sulfate or other nickel products are provided in which the ferronickel alloys are treated with oxidative leaching. The oxidative leaching can be, for example, pressure oxidation (POX) leaching or leaching with peroxide or copper (II) ions. The treatment can be in the presence of added copper, such as by providing a copper sulfate solution. The production of nickel sulfate can include removing copper and iron after leaching, removing impurities, and either crystallizing the nickel sulfate or precipitating / obtaining another nickel product.

Description

[Technical field]

[0001] The present disclosure relates to the direct refining of ferronickel alloys. [Background technology]

[0002] Ferronickel (FeNi) alloys are normally used to make stainless steel. A shortage of nickel sulfate, which is used to make lithium-ion batteries, is predicted until the mid-2020s.

[0003] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying figures. [Brief description of the drawings]

[0004] [Figure 1] 1 is a schematic diagram of a ferronickel (FeNi) direct refining process according to an embodiment of the present disclosure. [Diagram 2] 1 is a flow diagram of a general process for producing crystallized nickel sulfate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] The present disclosure provides a process for refining ferronickel alloys, where the ferronickel alloys are treated with oxidative leaching. This treatment can be in the presence of copper or peroxide. In certain embodiments, a process is provided for directly refining ferronickel to provide nickel sulfate or other valuable nickel products. In one or more embodiments, a process is provided for refining ferronickel alloys, where the ferronickel alloys are treated with pressure oxidation (POX) leaching, optionally in the presence of added copper. In one or more embodiments, a process is provided for refining ferronickel alloys, where the ferronickel alloys are leached in the presence of peroxide. It will be understood that other methods of leaching, with or without copper, can be used without departing from the spirit of the invention. For example, copper can be provided during the ferronickel alloy leaching process. The ferronickel alloys can be treated with POX in the presence of added copper. The ferronickel alloys can be treated with direct acid leaching in the presence of added copper. The ferronickel alloys can be treated with heap leaching in the presence of added copper. The ferronickel alloy may be a feedstock originally intended for use in the production of stainless steel. The ferronickel alloy may be any suitable feedstock containing iron and nickel, such as a ferronickel alloy produced from a saprolite feedstock. The ferronickel alloy may be processed in a vessel (such as a column) in the presence of copper. The ferronickel alloy may be processed in a column leach in the presence of hydrogen peroxide and sulfuric acid, optionally in the presence of added copper.

[0006] Ferronickel alloys containing little copper may benefit from increased copper content to accelerate leaching, such as in oxidative leaching.

[0007] In one or more embodiments, copper may be added as a first fill reagent. The added copper may be dissolved in the POX leachate and then fully solidified. The copper may be fully solidified onto a portion of the ferronickel alloy added after POX leaching. The fully solidified copper may be recycled back to the POX leachate.

[0008] In one or more embodiments, copper may be added continuously to the process. The added copper may be in the form of a copper concentrate or a copper sulfate solution. The added copper may be in the form of a copper-containing stream from a copper plant. The added copper may then be removed and recovered by any suitable method, such as by a solvent exchange step or other means such as electrowinning and / or cementation and / or sulfidation and / or ion exchange.

[0009] In one or more embodiments, the copper added to the process is added as a copper concentrate, such as a copper sulfide or copper oxide concentrate, or as copper sulfate or any other suitable copper-rich material. In one or more embodiments, the copper added to the process may be treated in a pre-leaching step, such as POX leaching, atmospheric leaching, or a roasting step to increase its solubility.

[0010] In one or more embodiments, a portion of the effluent of the oxidative leaching containing soluble copper may be returned to the oxidative leaching, such as to the POX autoclave, to provide soluble copper to react and / or to provide a coolant.

[0011] In one aspect, the present disclosure provides an improved direct refining process for ferronickel alloys, the improvement including adding copper to the ferronickel alloy in a leaching step, such as pressure oxidation (POX) leaching.

[0012] In one aspect, the present disclosure provides a process for the production of nickel sulfate, or a nickel battery material or intermediate feedstock therefor, comprising treating a ferronickel alloy feedstock with oxidative leaching, such as pressure oxidative (POX) leaching in the presence of added copper, removing copper and iron, removing other impurities, and crystallizing nickel sulfate or precipitating / obtaining another nickel product.

[0013] In one aspect, the present disclosure provides a process for producing nickel products from ferronickel that minimizes residues and environmental impacts by producing a hematite product that can be used for iron, a potassium sulfate product that can be sold for sulfate, and a combined concentrated impurity stream that is used as input for other metallurgical processes.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. As used in this specification and claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. The term "comprising" as used herein will be understood to mean that the ensuing list is non-exhaustive and may or may not include any other additional suitable items, such as one or more additional features, components and / or ingredients, as appropriate.

[0015] Ferronickel alloy leaching and refining Provided herein are processes and methods for refining ferronickel alloys, where the ferronickel alloys are treated with oxidative leaching. The oxidative leaching can be in the presence of copper. In one or more embodiments, the ferronickel alloys are treated with pressure oxidative (POX) leaching in the presence of copper.

[0016] The purification of the ferronickel alloy may include treating the ferronickel alloy in the presence of a peroxide. The treatment of the ferronickel alloy may be in the presence of sulfuric acid. In one or more embodiments, the ferronickel alloy is treated at atmospheric pressure in a vessel, such as a column, which may be referred to as column leaching. The treatment may occur in the presence of a peroxide, such as hydrogen peroxide, and sulfuric acid. The treatment may occur in the presence of copper. The treatment may occur in the presence of a peroxide and copper. The treatment may occur in the presence of hydrogen peroxide, sulfuric acid, and copper.

[0017] The ferronickel alloy may be pretreated beforehand or the process or method may include a pretreatment step. The pretreatment step may include particle size reduction, such as atomization or granulation. It will be understood that any suitable pretreatment step may be used. For example, if the oxidative leaching is a POX leaching, particle size reduction may be preferred, whereas if the oxidative leaching is a leaching in the presence of peroxide and sulfuric acid, particle size reduction may not be required.

[0018] The oxidation leaching may provide an effluent, at least a portion of which may be recycled. For example, the effluent may be returned to the oxidation leaching. The purification of the ferronickel alloy may include both a peroxide treatment and a POX treatment. In such a case, the peroxide treatment may include treating the ferronickel alloy in the presence of a peroxide to provide a first effluent, and the POX treatment may include treating the first effluent with POX to provide a second effluent. In such a case, one or both of the first and second effluents may be recycled. For example, the POX effluent (second effluent) may be returned to the peroxide treatment or to the POX treatment. Recycling of the effluent (such as the POX effluent) may help the leaching circuit to reduce acid consumption and / or increase the nickel concentration in the effluent.

[0019] As used herein, "pressure oxidation" (POX) may be used interchangeably with pressure oxidative leaching or pressure oxidation reaction. Pressure oxidation may be carried out in the presence of oxygen and sulfuric acid. Pressure oxidation may be carried out at any suitable temperature and pressure. Pressure oxidation may be carried out for any suitable length of time. POX may be carried out in an autoclave. POX may be used to leach ferronickel alloys. POX may be used to produce iron products, such as hematite. POX may be used to purify ferronickel alloys (such as ferronickel alloys in the form of an iron / nickel-rich pregnant leach solution), thereby producing hematite and an effluent containing dissolved nickel. POX may be used to purify ferronickel alloys before or after additional oxidative leaching, such as leaching in the presence of peroxide. For example, ferronickel alloys may be purified by oxidative leaching in the presence of peroxide and sulfuric acid, and may additionally be purified by POX. The effluent from the pressure oxidation step may be referred to as the POX effluent, or the second effluent (in embodiments where a first effluent is defined). The POX effluent may be a solution or a slurry. If the POX effluent is a slurry, the slurry may be processed using solid / liquid separation, such as using thickening and / or filtration techniques. The POX effluent may be used directly or may be processed (e.g., by solid / liquid separation) to provide a pregnant leach solution containing nickel, iron, and other impurities. If the POX effluent is processed by solid / liquid separation, it may also provide a solid phase or a thickened slurry containing hematite and other insoluble components.

[0020] As used herein, "oxidative leaching" can include any suitable leaching conditions for solubilizing at least a portion of the ferronickel alloy to leach the ferronickel alloy so that nickel and / or iron products can be obtained therefrom. The oxidative leaching can be pressure oxidation. The oxidative leaching can be carried out at atmospheric pressure, such as by leaching in a vessel in the presence of at least one oxidizing agent. The at least one oxidizing agent can include a peroxide, such as hydrogen peroxide. In one or more embodiments, the oxidizing agent can include hydrogen peroxide and sulfuric acid. The at least one oxidizing agent can include copper, with or without an additional oxidizing agent, such as a peroxide. The vessel can be a column. The oxidative leaching can be carried out with or without added copper. In one or more embodiments, copper is added to the oxidative leaching, such as to a POX leaching or column leaching. The oxidative leaching can provide an effluent. A portion of the effluent can be returned to the oxidative leaching. The oxidative leaching can include iron precipitation or hematite production. The effluent from the oxidation leach may be further processed, such as with solids removal, copper cementation, iron removal, nickel sulfate production, nickel hydroxide production, or other purification / pretreatment steps, and / or by inclusion of further steps as disclosed herein.

[0021] As used herein, "oxidative leaching" can include treating ferronickel alloy or pretreated ferronickel alloy solids or solutions in the presence of copper. Oxidative leaching in the presence of copper (e.g., in the form of sulfide, oxide, or sulfate) can be referred to as "copper treatment". Copper treatment can be the only or additional oxidative leaching step. In one or more embodiments, the copper treatment is a column leaching process. Copper treatment can occur in a single stage or multiple stages. When copper treatment is performed in multiple stages, each stage can vary in terms of pH and / or oxidation-reduction potential (ORP) to an appropriate level. In such cases, ferric ions, Fe(III), can be partially or completely converted to ferrous ions, Fe(II), by adding ferronickel alloy particles and / or reducing agents such as sulfur dioxide (SO2) before POX treatment for hematite production. In one or more embodiments, the process includes copper treatment to provide a first effluent. The first effluent may be returned to the copper processing so that the copper processing is carried out in multiple stages. The first effluent may be provided to a POX process, where the POX process may further leach the ferronickel alloy and / or precipitate hematite to provide a second effluent. The second effluent may be returned upstream, such as to an oxidative leaching step. In one or more embodiments, the second effluent may be returned to the copper processing step. The second effluent may then be further processed, such as to crystallize nickel sulfate. The processes and methods described herein may include a copper processing step, such as those described above, or the copper processing step may be omitted. It will be understood that the process or method may include another form of oxidative leaching step, such as a peroxide process or a POX process, and that the oxidative leaching step may be carried out in the presence or absence of added copper.

[0022] As used herein, "peroxide treatment" can include treating ferronickel alloy or pretreated ferronickel alloy solid or solution in the presence of peroxide. The peroxide treatment can be in the presence of hydrogen peroxide and sulfuric acid. In one or more embodiments, the peroxide treatment is a column leaching process, which can alternatively be referred to as column leaching. The peroxide treatment can be carried out in one stage or multiple stages. When the peroxide treatment is carried out in multiple stages, each stage can be varied in terms of pH and / or oxidation-reduction potential (ORP) to an appropriate level. In such a case, the ferric ion, Fe(III), can be partially or completely converted to the ferrous ion, Fe(II), by adding ferronickel alloy particles and / or a reducing agent such as sulfur dioxide (SO2) before the POX treatment for hematite production. In one or more embodiments, the process includes a peroxide treatment to provide a first effluent. The first effluent can be returned to the peroxide treatment so that the peroxide treatment is carried out in multiple stages. The first effluent may be provided to a POX process, which may further leach the ferronickel alloy and / or precipitate hematite to provide a second effluent. The second effluent may be returned upstream, such as to an oxidation leaching step. In one or more embodiments, the second effluent may be returned to a peroxide treatment step to recycle the acid. The second effluent may then be further processed, such as to crystallize nickel sulfate.

[0023] In one or more embodiments, the copper present in the leaching step may be fully consolidated after the leaching treatment. The copper formed in the copper cementation step may be used elsewhere in the process or method. In one or more embodiments, the copper formed in the copper cementation step may be recycled back to the leaching step, such as by oxidative leaching. It will be appreciated that the copper may be removed in any suitable manner, such as by cementation, solvent exchange, electrowinning, sulfidation, and / or ion exchange.

[0024] As used herein, "copper cementation" may refer to the process of precipitating solubilized copper ions.

[0025] In one or more embodiments, the process or method includes iron removal.

[0026] As used herein, "iron removal" may refer to a process that precipitates solubilized iron ions or an ion exchange process. For example, the iron removal process may include precipitation of iron to form hematite. The processes disclosed herein may include a hematite production step. The hematite production step may be a POX process. The process may include an oxidative leaching step and a hematite production step, although it will be understood that the two steps may occur simultaneously. For example, the process may include both a POX process to leach the ferronickel alloy and to form hematite and remove the iron. In one or more embodiments, the process may include an oxidative leaching, such as a peroxide process, to leach the ferronickel alloy, and such a process may further include a separate hematite production step, such as a POX process, to precipitate the dissolved iron and form hematite. The hematite production step may include forming basic ferric sulfate. The basic ferric sulfate may be solubilized, such as under acidic conditions, and re-dissolved, for example, during flushing. The processes disclosed herein may include iron by-product production. The processes may include iron by-product production instead of or in addition to hematite production. The iron by-product may include jarosite or goethite. Iron by-product production may depend on conditions and other steps in the process.

[0027] In one or more embodiments, the process as described herein includes purifying an aqueous solution comprising nickel sulfate (e.g., a sulfate matrix, pregnant leach solution (PLS)), where the PLS is subjected to any one or combination of purification steps (also referred to herein as impurity or component removal steps) to remove certain impurities or components. The terms pregnant leach solution (PLS) and effluent (e.g., oxidation leach effluent, or POX effluent) may be used interchangeably herein to refer to an aqueous solution comprising nickel sulfate. Any suitable solution comprising nickel sulfate may be used for further purification, such as to crystallize nickel sulfate.

[0028] After leaching, the PLS may undergo one or more purification steps to purify the PLS by removing one or more impurities or components. The type and amount of impurities or components to be removed will depend, at least in part, on the type of feedstock from which the PLS is formed, as well as the specifications of the final product (e.g., purity, grade nickel sulfate (NiSO4)) produced by the process. Examples of impurities or components to be removed include, but are not limited to, sodium (Na), aluminum (Al), iron (Fe), copper (Cu), zinc (Zn), lithium (Li), cobalt (Co), and manganese (Mn). If battery grade nickel sulfate is required, there will be specific product specifications (e.g., limits) regarding such impurities that are permitted; any such impurities, water, or reagents present in the process feedstock in amounts that exceed the product specifications will need to have their concentrations reduced.

[0029] There are many suitable methods for removing impurities or components from PLS. Such methods include, but are not limited to, precipitation, atmospheric or pressure leaching, sulfidation, solvent extraction, ion exchange, and cementation. The selection of an appropriate method (and its operating conditions) depends, at least in part, on the type and amount of impurities or components to be removed and the specifications of the end product produced by the process. For example, copper can be removed by precipitation, solvent extraction, sulfidation, cementation, ion exchange, etc.; iron and aluminum can be removed by precipitation, ion exchange, etc.; zinc can be removed by sulfidation, solvent extraction, ion exchange, etc.; cobalt can be removed by solvent extraction, ion exchange, or oxidation precipitation, etc. The conditions and operating parameters for each method are generally known and can be selected depending on the type and amount of impurities or components to be removed.

[0030] For example, cementation is a process involving a redox reaction between a first metal ion and a first solid metal, whereby the first metal ion is reduced to a second solid metal, which in turn is oxidized to the second metal ion. Cementation may be chosen, for example, to remove copper, because it can add precious metals to the process without the use of other reagents (e.g., by adding Ni if nickel powder is used as the first solid metal); and / or because it can allow for the removal of impurities (e.g., by reduction) without the need to add acid or base reagents to the process.

[0031] The purification steps for removing impurities or components from the PLS can be selected to minimize the use of acid or base reagents. For example, Cu can be removed by cementation with nickel powder, which requires little acid and no base and produces no acid; in contrast, removal of Cu by solvent extraction (SX) requires one mole of sulfuric acid per mole of Cu removed, and all of the added acid needs to be neutralized downstream by base. In another example, Cu can be removed by cementation with ferronickel feed particles through a single or multi-stage column, or granular / micronized ferronickel material in a vessel (such as a tank). Other impurities such as Fe and Al can be removed by precipitation by raising the pH (e.g., to about 5.5), which requires added base but no added acid; the base can be introduced as an external neutralizing agent or as a basic metal salt produced downstream in the process. In contrast, removal of Fe and Al by ion exchange (IX) requires added base to load the Fe and Al onto the exchange column, and it also requires added acid to strip the Fe and Al from the exchange column, and additional reagents or process steps to convert these impurities into easily disposable forms.

[0032] Nickel product manufacturing In one or more embodiments, the process or method includes the crystallization of nickel sulfate or the precipitation / obtaining of another nickel product.

[0033] In one or more embodiments, leaching (and purification) of the ferro-nickel alloy results in a nickel sulfate solution or solid (e.g., sulfate matrix, pregnant leach solution (PLS) or POX effluent). The aqueous solution containing nickel sulfate may be crystallized to form crystallized nickel sulfate, such as battery grade nickel sulfate. In one or more embodiments, a process for producing a metal sulfate, such as nickel sulfate or nickel sulfate and cobalt sulfate, may be provided. In one or more embodiments, a process for producing nickel sulfate may be provided, comprising: crystallizing nickel sulfate from an aqueous solution to form crystallized nickel sulfate in a mother liquor (the mother liquor comprising uncrystallized nickel sulfate); separating the crystallized nickel sulfate from the mother liquor. The process may further comprise basifying a portion of the mother liquor to convert the uncrystallized nickel sulfate to a basic nickel salt. The basic nickel salt may be nickel hydroxide. The basic nickel salt may be used upstream of the crystallization of the nickel sulfate.

[0034] In one or more embodiments of the process described herein, using the basic nickel salt upstream may include converting the basic nickel salt back to non-crystallized nickel sulfate. Converting the basic nickel salt back to non-crystallized nickel sulfate may include using the basic nickel salt as a first neutralizing agent to neutralize acid upstream of the nickel sulfate crystallization. Basifying a portion of the mother liquor to convert the non-crystallized nickel sulfate to basic nickel salt may further include draining the mother liquor and controlling the draining rate to produce an amount of basic nickel salt that is at least approximately equivalent to the amount of acid neutralized upstream of the nickel sulfate crystallization. Using the basic nickel salt as a first neutralizing agent may include using the basic nickel salt as a first neutralizing agent in the leaching stage; or includes using the basic nickel salt as a first neutralizing agent in the purification stage.

[0035] In one or more embodiments of the process described herein, basifying a portion of the mother liquor may include the use of a second neutralizing agent to convert the non-crystallized nickel sulfate to a basic nickel salt. The second neutralizing agent may be sodium hydroxide, which may be converted to sodium sulfate when converting the non-crystallized nickel sulfate to a basic nickel salt. The process may further include converting the sodium sulfate back to sodium hydroxide by electrolysis. The second neutralizing agent may be any one or combination of potassium hydroxide, calcium hydroxide, lithium hydroxide, or magnesium oxide. The use of any one or combination of potassium hydroxide, calcium hydroxide, lithium hydroxide, or magnesium oxide may form any one or combination of potassium sulfate, calcium sulfate, lithium sulfate, or magnesium sulfate as a by-product.

[0036] In one or more embodiments of the process described herein, the process may further include crystallizing the uncrystallized nickel sulfate. The crystallization of nickel sulfate may further include draining the mother liquor and controlling the drainage rate to selectively inhibit crystallization of impurities when crystallizing nickel sulfate. The crystallization of nickel sulfate may further include controlling the amount of free water in the crystallizer to selectively inhibit crystallization of impurities when crystallizing nickel sulfate. Controlling the amount of free water may include controlling the rate of water evaporation from the crystallizer or controlling the addition of water to the crystallizer. The impurities may include lithium, sodium, potassium, manganese, or ammonium. In this context, "impurities" refer to components of the feedstock that are not nickel sulfate as described herein or that do not contribute to the formation of nickel sulfate or crystallized nickel sulfate as described herein. As used herein, "impurities" may be useful, valuable, or desirable materials once isolated from the feedstock.

[0037] In one or more embodiments of the processes described herein, the process may further include isolating the basic nickel salt from the mother liquor. Isolating the basic nickel salt may include using a one or two stage precipitation circuit and selectively precipitating the basic nickel salt. The basic nickel salt may include nickel hydroxide.

[0038] In one or more embodiments of the processes described herein, the crystallized nickel sulfate can be battery-grade crystallized nickel sulfate or electroplating-grade crystallized nickel sulfate. Of the crystallized nickel sulfate isolated from the process, some can be nickel sulfate hydrate (e.g., crystallized nickel sulfate and water molecules combined in various ratios as an integral part of the crystal; e.g., one water molecule per nickel sulfate, or six water molecules per nickel sulfate, or seven water molecules per nickel sulfate).

[0039] In one or more embodiments, the process as described herein may further include purifying the aqueous solution comprising nickel sulfate (e.g., sulfate matrix, pregnant leach liquor (PLS)), where the PLS is subjected to any one or combination of purification steps (also referred to herein as impurity or component removal steps) to remove specific impurities or components, such as Cu (e.g., by sulfidation, solvent extraction, cementation, ion exchange, etc.), Fe and Al (e.g., by precipitation, ion exchange, etc.), Zn (e.g., by sulfidation, solvent extraction, ion exchange, etc.), Co (e.g., by solvent extraction, ion exchange, precipitation, etc.), Ca (e.g., by solvent extraction, ion exchange, etc.), or Mg (e.g., by solvent extraction, ion exchange, etc.). The purified PLS may then be introduced into a crystallizer under conditions sufficient to selectively crystallize nickel sulfate (NiSO4) from the purified PLS to produce crystallized nickel sulfate in a mother liquor (e.g., by forced circulation, such as under vacuum, against lithium, magnesium, sodium, potassium or ammonium, depending on the feedstock). These crystallized nickel sulfate are then isolated from the mother liquor (e.g., discharged from a crystallizer). If one crystallization cycle (e.g., using one crystallizer) is insufficient to produce crystallized nickel sulfate (which can occur, for example, with feedstocks containing higher concentrations of impurities), the crystals discharged from the crystallizer can be dissolved in pure water to form an aqueous sulfate solution and then introduced into a second crystallization cycle (e.g., using a second crystallizer) for recrystallization.

[0040] After crystallization, the mother liquor may contain undesired salts / metals (e.g., Li2SO4, MgSO4, Na2SO4, CoSO4, (NH4)2SO4, K2SO4, etc.) as well as nickel sulfate that did not crystallize out of solution (also referred to herein as uncrystallized nickel sulfate). To selectively recover these uncrystallized nickel sulfates from the remaining undesired materials in solution, the mother liquor is drained from the crystallizer and basified to convert the uncrystallized nickel sulfate to basic nickel salts, such as nickel hydroxide (Ni(OH)2). These nickel hydroxides may be used upstream to neutralize acids introduced during the leaching and / or purification steps of the process to form the PLS, thus converting the nickel hydroxide back to nickel sulfate, which can then be isolated by crystallization. Prior to upstream use, the nickel hydroxide may be isolated from the mother liquor, washed, and reslurried with water for transfer, which limits exposure to air and thus oxidation of the hydroxide.

[0041] In addition to or instead of using nickel hydroxide as a neutralizing agent, the process uses an external source of neutralizing agent (e.g., added oxide, hydroxide) to basify the mother liquor exiting the crystallizer, and optionally neutralize the acid introduced during the leaching and / or purification steps. These external neutralizing agents are selected either for their ability to be regenerated (e.g., by electrolysis, etc.) from their waste streams to minimize or avoid forming waste streams (e.g., CaO / CaCO3 as a reagent, CaSO4·2H2O as a waste stream; NaOH as a reagent, Na2SO4 as a waste stream); or for their ability to generate more highly valued by-products (e.g., KOH as a reagent, K2SO4 as a by-product).

[0042] In one or more embodiments of the present disclosure, a process is provided as depicted in Figure 1 or Figure 2 or as described in Example 1. In one or more embodiments of the process and method of the present disclosure, a process is provided as depicted in Figure 2, where: the leaching and purification step includes pretreating a ferronickel alloy feedstock as described herein to form a pre-leached feedstock, and subjecting the pre-leached feedstock to a leaching and purification step to form a purified, leached solution containing uncrystallized nickel sulfate; the crystallization step includes introducing the purified, leached solution into a crystallizer, and forming crystallized nickel sulfate in a mother liquor (the mother liquor includes the remaining uncrystallized nickel sulfate), and separating the crystallized nickel sulfate from the mother liquor; and the basification step includes basifying a portion of the mother liquor to convert the remaining uncrystallized nickel sulfate to a basic nickel salt; and using the basic nickel salt upstream of the crystallization of the nickel sulfate; for example, as a neutralizing agent to neutralize an acid upstream of the crystallization of the nickel sulfate.

[0043] Crystallization The processes and methods described herein may include crystallizing a metal sulfate from an aqueous solution to form a crystallized metal sulfate, such as nickel sulfate, cobalt sulfate, or a combination thereof. An aqueous solution, such as purified PLS, may be introduced into a crystallizer under conditions sufficient to selectively crystallize the metal sulfate from solution. Such selective crystallization occurs against components, such as lithium, sodium, potassium, magnesium, ammonium, etc. (depending on the feedstock) remaining in the purified PLS to provide one or more crystallized metal sulfates in the mother liquor.

[0044] Different types of crystallizers may be suitable to affect selective crystallization or co-crystallization of metal sulfates, such as nickel sulfate crystallization or nickel sulfate and cobalt sulfate co-crystallization. Such crystallizers include, but are not limited to, evaporative crystallizers, forced circulation (FC) crystallizers, indirect forced circulation (IFC) crystallizers, and draft tube baffle (DTB) crystallizers. The conditions and operating parameters for such crystallizers can be selected depending on the type and purity of nickel sulfate to be crystallized and / or the type and concentration of impurities in the PLS. For example, if an IFC or DTB crystallizer is used, coarser crystals may be formed when crystallizing nickel sulfate; this may prevent the entrainment of impurities, such as lithium, sodium, magnesium, and / or potassium, during said crystallization. If a forced circulation crystallizer is used, it may be operated under vacuum to flash cool the PLS to ambient temperature (e.g., about 25° C.), which in turn may facilitate evaporation of water and metal salt crystallization. In such cases, the amount of free water evaporated may be less than the amount required to reach the saturation point of a particular impurity, such as lithium or sodium. When a crystallizer is used to selectively crystallize nickel sulfate as opposed to impurities such as lithium and sodium, the crystallizer may be operated at a pH level between 1 and 5, or between 1.5 and 2.5. In some embodiments, pH levels below 0, below 1.5, or between 0.5 and 1.5 are effective.

[0045] The crystallizer conditions and operating parameters may be selected to selectively crystallize nickel sulfate over other sulfates and components (e.g., impurities) in the solution. The crystallizer conditions and operating parameters may be selected to selectively co-crystallize nickel sulfate and cobalt sulfate over other sulfates and components (e.g., impurities) in the solution. The crystallizer conditions and operating parameters may also be selected to control the purity of the crystallized metal sulfate. The drainage of the mother liquor from the crystallizer during crystallization, and the rate at which the drainage occurs, can affect the purity of the crystallized nickel sulfate, for example, by selectively inhibiting the crystallization of the impurity. As used herein, selecting a drainage rate to selectively inhibit the crystallization of a particular impurity means setting the crystallizer drainage rate within a range of possible drainage rates that inhibits the crystallization of the particular impurity more than it would inhibit the crystallization of a different impurity. The drainage rate may be selected such that it maximizes inhibition of crystallization of the particular impurity. The impurity may be sodium, potassium, magnesium, etc. The use of a higher drainage rate of the mother liquor helps to maintain a lower concentration of impurities and other components in the mother liquor, which could affect the purity of the crystallized nickel sulfate.

[0046] Furthermore, impurity solubility is temperature dependent; therefore, the crystallizer temperature as well as the crystallizer drainage rate can be effective in controlling the purity of the metal sulfate during crystallization.

[0047] Impurity solubility can also be dependent on the amount of free water present in the PLS and / or mother liquor; therefore, controlling the water level in the crystallizer can be an effective means of controlling the purity of the metal sulfate during crystallization. For example, in some cases, the metal sulfate crystallizes out of solution as metal sulfate hydrates (i.e., crystallized metal sulfate and water molecules combined in a defined ratio as an integral part of the crystal), which reduces the concentration of water in the mother liquor. By reducing the concentration of free water, the concentration of impurities (e.g., lithium, sodium, potassium, magnesium, etc.) in the mother liquor can also increase to the point where they crystallize out of solution, affecting the purity of the crystallized metal sulfate. However, if a sufficient amount of water is added to the PLS and / or mother liquor while in the crystallizer, or if there is an amount of excess water (e.g., at least as much water as would be expected to be lost by hydrate formation) remaining in the PLS after upstream processing, the presence of that free water can prevent the impurities from crystallizing out of solution.

[0048] Crystallized metal sulfates, such as nickel sulfate or nickel sulfate and cobalt sulfate, can be isolated from the mother liquor by discharging them from the crystallizer. For example, the crystallized metal sulfates can be discharged as a slurry, and the slurry is passed through a filter or centrifuge to separate the crystals from the mother liquor. The filtrate or concentrate (i.e., mother liquor) can then be passed back through the crystallizer, or a portion of it can be drained; the isolated crystals are washed on the filter or centrifuge and dried. In some cases, the use of only one crystallizer is insufficient to produce adequately pure crystallized metal sulfates, such as when the PLS is formed from a dirtier feedstock. The crystals discharged from the first crystallizer are then dissolved in water (e.g., pure water) and then recrystallized and introduced into a second crystallizer for further purification.

[0049] In some embodiments, the processes described herein can help reduce capital and operating costs by isolating crystallized metal sulfate salts using a crystallizer instead of a solvent extraction circuit. Although crystallization requires energy input, it does not require the use of additional reagents, thereby helping to reduce operating costs. Furthermore, the capital costs associated with crystallization are lower than those associated with a solvent extraction circuit.

[0050] In other embodiments, the processes described herein reduce capital and operating costs by reducing the use of reagents. For example, a nickel solvent extraction circuit to form nickel sulfate requires one mole of sulfuric acid and two moles of sodium hydroxide per mole of nickel sulfate produced. In contrast, crystallization does not require the use of any additional reagents. The processes described herein may help reduce reagent usage, even when a solvent extraction step is used as part of a purification stage, since the solvent extraction will generally experience a smaller load (i.e., impurities at a lower concentration) and therefore require less acid and base. In some embodiments, the processes described herein may help reduce capital and operating costs by reducing the number of processing steps. Reducing the number of process steps not only reduces capital and operating costs, but it also reduces the complexity of the process and therefore the complexity of the infrastructure and the skill set required to carry out the process. For example, solvent extraction is a relatively complex unit operation that requires multiple stages of extraction, scrubbing, and stripping; as well as systems for treating aqueous exhaust streams, crud removal, organic vapor recovery, and fire protection. By isolating crystallized nickel sulfate using a crystallizer instead of a solvent extraction circuit, such process complications (and associated costs) can be reduced or avoided altogether.

[0051] In other embodiments, the processes described herein may help to increase the yield of crystallized metal sulfate by reducing or preventing the addition of certain impurities or components in the leaching and / or purification stages of the process, such as lithium, sodium, potassium, or magnesium. For example, as the single-pass yield of crystallized nickel sulfate goes up in the crystallizer, the concentration of impurities such as lithium, sodium, etc. in the mother liquor may also increase. As a result, the crystallizer bleed rate must also be increased to manage the purity of the crystallized nickel sulfate (e.g., by inhibiting or preventing the impurities from approaching their saturation concentration in the mother liquor). However, increasing the crystallizer bleed rate may create inefficiencies, as the bled, uncrystallized nickel sulfate would be basified and precipitated, consuming reagents. Thus, reducing or preventing the addition of these impurities in the leaching and / or purification stages of the process means that the crystallizer may be able to operate at a lower bleed rate while avoiding co-crystallization of the impurities with nickel sulfate, which may improve the single-pass yield of crystallized nickel sulfate while also lowering operating costs. In one or more embodiments of the disclosed process, the addition of certain impurities (e.g., lithium, sodium, magnesium, etc.) can be reduced or prevented by using basic metal salts (e.g., metal hydroxides Ni(OH)2, Co(OH)2, Mn(OH)2, etc.) that are precipitated from the mother liquor draining from the crystallizer. In some embodiments, the precipitation and washing of the basic metal salt can be carefully controlled (e.g., by selection of pH levels, use of a two-stage precipitation circuit, etc.) to reduce or prevent precipitation of impurities (e.g., lithium, sodium, magnesium, etc.) into the basic metal salt.

[0052] In some embodiments, the processes described herein may increase the yield of crystallized nickel sulfate by using a loop to isolate and basify the crystallization mother liquor to convert the uncrystallized nickel sulfate in solution to basic nickel salts (e.g., nickel hydroxide), and by using those basic nickel salts as neutralizing agents to convert the salts back to nickel sulfate for crystallization. The repetitive nature of the loop may help ensure good recovery of the crystallized nickel sulfate.

[0053] In other embodiments, the processes described herein may reduce or eliminate sodium sulfate as a waste stream by regenerating sodium hydroxide from sodium sulfate, a by-product of poor marketability that is commonly feared to be a costly waste disposal problem, both from an environmental and financial standpoint.

[0054] Basification The processes and methods described herein may include basifying a portion of the mother liquor. The basifying a portion of the mother liquor may be to convert non-crystallized metal sulfates to basic metal salts. The basifying a portion of the mother liquor may be to convert non-crystallized metal sulfates (such as nickel sulfate or nickel sulfate and cobalt sulfate) to basic metal salts (such as nickel hydroxide or nickel hydroxide and cobalt hydroxide). The basifying a portion of the mother liquor may be to convert non-crystallized nickel sulfate to basic nickel salts, such as nickel hydroxide. In one or more embodiments of the processes described herein, the process may include basifying a portion of the mother liquor using a second neutralizing agent to convert non-crystallized nickel sulfate to basic nickel salts. In one or more embodiments, converting the basic nickel salt back to non-crystallized nickel sulfate may include neutralizing an acid upstream of the crystallization of nickel sulfate using a basic nickel salt as a first neutralizing agent.

[0055] The crystallization mother liquor contains uncrystallized metal sulfates (nickel or nickel and cobalt) in addition to other impurities and components, such as metals and salts such as Li2SO4, Na2SO4, etc. It will be understood that the following discussion of nickel sulfate may also apply to other metal sulfates, such as nickel sulfate and cobalt sulfate. To selectively recover these uncrystallized nickel sulfates and to form a basic nickel salt for upstream use as a neutralizing agent (also referred to herein as a first neutralizing agent), the mother liquor may be drained from the crystallizer and basified to convert the uncrystallized nickel sulfate remaining in the mother liquor to said basic nickel salt, such as nickel hydroxide (Ni(OH)2). When basifying the mother liquor, sufficient base may be added to raise the pH level to 7.5-10, or 7.5-9.5. The resulting nickel hydroxide precipitates from the mother liquor and may be isolated from the mother liquor by filtration, washed to form a cake, and repulped to form a slurry. For example, the nickel hydroxide may be recovered by filtration, concentration and filtration, or centrifugation, and then washed on a filter or centrifuge to form a cake. At least a portion of the cake may be passed to a repulping tank and slurried with water or process liquor. The nickel hydroxide may be selectively precipitated from the mother liquor, for example, by a one- or two-stage precipitation circuit. The precipitation circuit may be used to selectively precipitate the nickel hydroxide from impurities in the nickel hydroxide due to their presence in the mother liquor.

[0056] In one or more embodiments, metal hydroxide (such as nickel hydroxide and / or cobalt hydroxide) may be introduced upstream in the process. For example, nickel hydroxide may be used as a neutralizing agent to neutralize the acid introduced in the leaching and / or purification steps. For example, about 0% to 40% of the nickel hydroxide (e.g., as a cake) may be introduced to the leaching step; about 60% to 100% of the nickel hydroxide (e.g., as a cake) may be introduced to the purification step. The use of nickel hydroxide as a neutralizing agent reduces and / or eliminates the need to introduce an external neutralizing agent; this reduces reagent usage (and associated costs) as well as reduces and / or eliminates an additional source of impurities that may affect product purity (e.g., impurity metal cations from the external neutralizing agent) and that would otherwise require higher crystallizer bleed rates to avoid co-precipitation of impurities and contaminants in the crystallized nickel sulfate. In some cases, to help ensure that there is a sufficient amount of basic nickel salt, e.g., nickel hydroxide, available for use as a neutralizing agent, the rate at which the mother liquor is drained from the crystallizer and basified to form nickel hydroxide can be controlled so that the amount of nickel hydroxide formed is at least about equal to, or about equal to, the amount of acid introduced in the leaching and / or purification steps. For example, if the purified PLS is of high purity, the crystallizer drain rate may not need to be very high to control the purity of the crystallized nickel sulfate (e.g., as described above); however, the crystallizer drain rate may nevertheless need to be increased to ensure that a sufficient amount of nickel hydroxide is formed for upstream use. In other cases, the rate at which the mother liquor is drained from the crystallizer and basified to form nickel hydroxide can be controlled so that the amount of nickel hydroxide formed in combination with the amount of external neutralizing agent added is at least approximately equal to the amount of acid introduced in the leaching and / or purification steps; however, the amount of external neutralizing agent added can be kept low enough so that the use of the external neutralizing agent does not introduce impurities (e.g., impurity metal cations) at concentrations that would affect the purity of the crystallized nickel sulfate.In such cases, a combination of the formed nickel hydroxide with an external neutralizing agent may be used to manage capital and / or operating costs. Additionally, the rate at which nickel hydroxide is metered to an upstream process may be controlled by the pH set point for that process (e.g., leaching, purification, etc.).

[0057] Additionally, the use of a basic metal salt (e.g., nickel hydroxide) as a neutralizing agent can convert the basic metal salt back to metal sulfate within the purified PLS. The purified PLS, including the converted metal sulfate, can then proceed to a crystallizer where the converted metal sulfate can be crystallized and isolated from the mother liquor. This loop of isolating and basifying the mother liquor to convert the non-crystallized metal sulfate in solution to basic metal salts, and using those basic metal salts as neutralizing agents to convert the basic metal salts back to metal sulfates (which can then be isolated by crystallization) can help improve the yield of isolated, crystallized metal sulfate from a particular feedstock.

[0058] In addition to the use of a basic metal salt, e.g., nickel hydroxide, as a neutralizing agent, the process may use an external source of neutralizing agent (e.g., an added oxide, hydroxide, etc.) (also referred to herein as a second neutralizing agent) to neutralize the acid in the refining step and / or to basify the mother liquor bleed from the crystallizer. The selection of the type and amount of external neutralizing agent may depend, at least in part, on the nature of the refining step and the type of nickel sulfate and other components in the mother liquor. There are different types of external neutralizing agents that may be suitable for use in the refining step and / or for use in basifying the mother liquor. Suitable external neutralizing agents include, but are not limited to, potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), sodium hydroxide (NaOH), lithium hydroxide (LiOH), or magnesium oxide (MgO). For example, any one or combination of potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), sodium hydroxide (NaOH), lithium hydroxide (LiOH), and magnesium oxide (MgO) may be used as the external neutralizing agent. There are types of external neutralizing agents that are less suitable for use in the purification step and / or for use in basifying the mother liquor. For example, the use of ammonia as an external neutralizing agent may result in the formation of double salts, or nickel complexes, such as nickel ammonium sulfate. Such cations, salts or complexes may make the process less viable and / or increase operating and capital costs due to the required solvent extraction circuit.

[0059] The amount of external neutralizing agent may be selected depending on the nature of the refining step. For example, if there is a high concentration of Cu that needs to be removed in the refining step, a high concentration / volume of neutralizing agent may be required to neutralize any acid generated in the copper solvent extraction step. Additionally, if there is a high concentration of Fe that needs to be removed in the refining step, a high concentration / volume of neutralizing agent will be required to increase the pH and remove the Fe by hydrolysis.

[0060] The type of external neutralizing agent may be selected to produce and recover a particular by-product from the salt recovery step, such as a by-product having commercial value. For example, if the external neutralizing agent is selected to be potassium hydroxide, its use may produce potassium sulfate (K2SO4), a fertilizer. If the external neutralizing agent is selected to be calcium hydroxide, its use may produce gypsum (CaSO4·2H2O), a product that may be treated as waste or used in drywall and construction. If the external neutralizing agent is selected to be magnesium oxide (MgO), its use may produce magnesium sulfate. If the external neutralizing agent is selected to be lithium oxide (LiOH), its use may produce lithium sulfate.

[0061] The type of external neutralizing agent may also be selected based on its ability to be recovered and regenerated by a salt recovery step so that the neutralizing agent can be used in the process and then regenerated for reuse. For example, if the external neutralizing agent is selected to be sodium hydroxide, its use may produce sodium sulfate as a by-product. Sodium hydroxide can be regenerated from sodium sulfate by electrolysis. Generally, electrolysis can convert the by-product sodium sulfate directly back to sodium hydroxide for reuse in the process, producing sulfuric acid during this conversion. More specifically, electrolysis is performed using an electrochemical cell that uses an applied potential and one or more ion selective membranes to regenerate the acid and base from the salt solution and can include two or more compartments separated by selective membranes. For example, electrolysis can be performed at 1500-3000 A / m 2 The present invention may involve a three-compartment cell operating under a potential of 6 V at a current density of 0.15 to 1.0 V, which may produce from sodium sulfate an approximately 20% by weight solution of sodium hydroxide together with an approximately 10% by weight solution of sulfuric acid, both of which may be recycled for use upstream in the process. If the external neutralizing agent is selected to be LiOH, its use may produce lithium sulfate which may be converted back to LiOH using downstream recovery steps such as basification and crystallization, or electrolysis, or may be converted to lithium carbonate as a saleable product.

[0062] In one or more embodiments, the processes described herein do not use a solvent extraction circuit to isolate battery-grade, crystallized nickel sulfate. In one or more embodiments, the processes described herein help to reduce capital and operating costs; increase the yield of crystallized nickel sulfate; and / or reduce or eliminate sodium sulfate as a solid waste product (if sodium hydroxide is used as an external neutralizing agent and sodium sulfate is converted back to sodium hydroxide by electrolysis or the amount of external neutralizing agent required is reduced). EXAMPLES

[0063] Example 1 FIG. 1 shows a schematic diagram of a FeNi (ferronickel) alloy direct refining process according to certain embodiments of the present disclosure. The FeNi alloy is subjected to pressure oxidation (POX) leaching, followed by solids removal, and then copper cementation. The fully consolidated copper in the copper cementation step is then recycled back to the POX leaching. The fully consolidated copper in the copper cementation step can be treated with pre-leaching and then recycled back to the POX leaching. Further processing steps can include iron removal and nickel sulfate production. Further processing steps can include nickel hydroxide crystallization. In one or more embodiments, the process further includes processing to precipitate nickel hydroxide for use upstream in the process, including in connection with copper cementation and / or iron removal.

[0064] In this example, granular / micronized FeNi particles are provided directly to a POX autoclave for copper assisted POX leaching; leaching and hematite production occur in one unit operation.

[0065] Example 2 The process of Example 1 may be carried out with the following modifications: instead of the FeNi alloy being directly treated with pressure oxidation (POX) leaching, the FeNi alloy may instead be treated with leaching in a vessel (such as a column) in the presence of peroxide and sulfuric acid.

[0066] As an alternative or complement to the copper-assisted POX leaching described in Example 1 and FIG. 1, hydrogen peroxide can be used as an oxidizing agent in column leaching to dissolve ferronickel in the presence of sulfuric acid. In this example, FeNi alloy shot (having a larger particle size than the granular / micronized FeNi particles of Example 1) is provided to a peroxide / sulfuric acid leaching column, thereby leaching ferronickel in one step. In a second step, the effluent from the leaching column is sent to POX to precipitate hematite. In this example, no copper was added to the POX step. In this process, the POX PLS (or second effluent) can be recycled to the peroxide-assisted leaching circuit to reduce acid consumption and increase nickel concentration. By increasing the nickel concentration, the autoclave operation can enable high acidity and high iron throughput. Since the nickel concentration is controlled by the PLS recycle stream, the stability of the autoclave operating conditions can be improved. Another advantage of the high nickel concentration PLS may be that it helps to reduce downstream flow rates for nickel production, thus reducing capital costs.

[0067] The recycle ratio of the PLS can be adjusted to reduce the formation of basic sulfates or goethite. The desired iron product in the process is hematite due to its high iron content, low sulfur content and marketability potential.

[0068] After oxidative leaching, this example can be carried out in the same manner, including solids removal, followed by copper cementation (if copper was added to the oxidative leaching). Further processing steps can include those listed above with respect to Example 1.

[0069] Example 3 The process of Example 1 may be carried out with the following modification: instead of the FeNi alloy being directly subjected to pressure oxidation (POX) leaching, the FeNi alloy may instead be subjected to leaching in a vessel (such as a column) in the presence of added copper.

[0070] As an alternative or complement to the copper-assisted POX leaching described in Example 1 and FIG. 1, copper can be used as an oxidizing agent in column leaching to dissolve ferronickel. The added copper can be any suitable source of copper ions, such as a copper sulfate solution. The treatment can be with or without pretreatment, such as granulation or atomization of the FeNi alloy. The treatment can be carried out as a single stage or multiple stages. After treatment, the copper can be fully consolidated in the form of a sponge and leaves the column. The copper can be recycled. For example, the copper can be returned to the oxidative leaching stage or directly to the POX leaching process, such as that of Example 1.

[0071] Embodiment 1. A process for refining ferronickel alloy, comprising: Treating ferronickel alloys by oxidation leaching A process including.

[0072] 2. The process of embodiment 1, wherein treating the ferronickel alloy with oxidative leaching comprises treating the ferronickel alloy with pressure oxidation (POX) leaching.

[0073] 3. The process of embodiment 1 or 2, wherein treating the ferronickel alloy with oxidative leaching comprises treating the ferronickel alloy in the presence of copper.

[0074] 4. The process of any one of embodiments 1-3, wherein treating the ferronickel alloy with oxidative leaching comprises treating the ferronickel alloy in the presence of a peroxide.

[0075] 5. The process of any one of embodiments 1-4, wherein treating the ferronickel alloy with oxidative leaching comprises treating the ferronickel alloy in the presence of sulfuric acid.

[0076] 6. The process of any one of the preceding embodiments, wherein treating the ferronickel alloy with oxidative leaching comprises treating the ferronickel alloy in a vessel, such as a column, at atmospheric pressure.

[0077] 7. Treating ferronickel alloys with oxidative leaching is providing a peroxide treatment comprising treating a ferro-nickel alloy in the presence of peroxide and sulfuric acid to provide an effluent; providing a POX treatment, comprising treating the effluent with POX; The process of any one of embodiments 4 to 6, comprising:

[0078] 8. The process of any one of embodiments 3 to 7, wherein the copper is provided as copper sulfide, copper oxide, or copper sulfate.

[0079] 9. Pretreating the ferronickel alloy before subjecting it to oxidation leaching The process of any one of embodiments 1 to 8, further comprising:

[0080] 10. The process of embodiment 9, wherein pretreating the ferronickel alloy includes particle size reduction, such as atomization or granulation.

[0081] 11. The process of any one of the preceding embodiments, wherein the oxidative leaching provides an effluent, and at least a portion of the effluent is returned to the oxidative leaching.

[0082] 12. Treating ferronickel alloys with oxidative leaching is providing a peroxide treatment comprising treating the ferronickel alloy in the presence of a peroxide to provide a first effluent; providing a POX process comprising treating a ferro-nickel alloy with POX to provide a second effluent; Returning at least a portion of the second effluent to the peroxide treatment. 8. The process of embodiment 7, comprising:

[0083] 13. The process of embodiment 12, wherein returning the second effluent to the peroxide treatment enhances the concentration of nickel in the peroxide treatment.

[0084] 14. The process of embodiment 12 or 13, wherein returning the second effluent to the peroxide treatment adjusts the pH of the peroxide treatment.

[0085] 15. Manufacturing iron products 15. The process of any one of embodiments 1 to 14, further comprising:

[0086] 16. The process of embodiment 15, wherein producing the iron product comprises producing hematite, jarosite, or goethite.

[0087] 17. The process of embodiment 16, wherein producing the iron product comprises selectively removing iron in the form of hematite by pressure oxidation (POX) of the ferronickel alloy.

[0088] 18. The process of any one of embodiments 3 to 17, further comprising a copper recovery step after oxidative leaching to recover at least a portion of the copper.

[0089] 19. The process of embodiment 18, wherein the copper recovery step comprises a solvent extraction step, an electrowinning step, a cementation step, a sulfidation step, a pH adjustment step, an ion exchange step, or a pressure oxidation step.

[0090] 20. The process of embodiment 19, wherein the copper recovery step includes a cementation step, and a portion of the ferro-nickel alloy or nickel powder is provided to cement the copper.

[0091] 21. The process of embodiment 19 or 20, wherein the copper recovery step comprises a cementation step in a vessel, such as a column.

[0092] 22. The process of any one of embodiments 18 to 21, wherein at least a portion of the recovered copper is returned upstream to the step of treating the ferronickel alloy with oxidative leaching or to a pre-leaching step upstream of the oxidative leaching treatment step.

[0093] 23. The process of any one of embodiments 3 to 22, wherein copper is added to the process during the copper cementation step, the oxidative leaching, or a pre-leaching step upstream of the oxidative leaching.

[0094] 24. The process of any one of embodiments 3 to 23, wherein the copper comprises a copper-containing stream from a copper plant.

[0095] 25. Manufacturing nickel products 25. The process of any one of embodiments 1 to 24, further comprising:

[0096] 26. The process of embodiment 25, wherein oxidative leaching provides an effluent containing uncrystallized metal sulfate, and producing the nickel product comprises crystallizing the uncrystallized metal sulfate to form crystallized nickel sulfate or co-crystallized nickel and cobalt sulfate in the mother liquor.

[0097] 27. The process of embodiment 26, wherein the nickel product is crystallized nickel sulfate.

[0098] 28. The process of embodiment 26 or 27, further comprising purifying the effluent before crystallization.

[0099] 29. The process of any one of embodiments 26-28, further comprising separating the crystallized nickel sulfate or co-crystallized nickel and cobalt sulfate from the mother liquor.

[0100] 30. The process of embodiment 29, wherein the mother liquor contains residual non-crystallized metal sulfate, further comprising basifying a portion of the mother liquor to convert the residual non-crystallized metal sulfate to a basic metal salt.

[0101] 31. The process of embodiment 30, further comprising using a basic metal salt upstream of the crystallization of the metal sulfate.

[0102] 32. The process of embodiment 31, wherein the upstream use of the basic metal salt comprises converting the basic metal salt back to a non-crystallized metal sulfate.

[0103] 33. An improved process for direct refining of ferronickel alloys, the improvement including providing copper during leaching of the ferronickel alloy.

[0104] 34. The method of embodiment 33, wherein leaching the ferronickel alloy comprises oxidative leaching.

[0105] 35. A process for producing nickel products comprising: treating a ferronickel alloy feedstock with oxidative leaching to form a leached material, the leached material comprising nickel and iron; removing at least a portion of the iron from the leached material; To recover nickel products A process including.

[0106] 36. The process of embodiment 35, wherein treating the ferronickel alloy feedstock with oxidative leaching comprises treating the ferronickel alloy feedstock with pressure oxidation (POX) leaching.

[0107] 37. The process of embodiment 35 or 36, wherein treating the ferronickel alloy feedstock with oxidative leaching comprises treating the ferronickel alloy feedstock in the presence of copper.

[0108] 38. The process of any one of embodiments 35-37, wherein treating the ferronickel alloy feedstock with oxidative leaching comprises treating the ferronickel alloy feedstock in the presence of a peroxide.

[0109] 39. The process of any one of embodiments 35-38, wherein treating the ferronickel alloy feedstock with oxidative leaching comprises treating the ferronickel alloy feedstock in the presence of sulfuric acid.

[0110] 40. The process of embodiment 38 or 39, wherein treating the ferronickel alloy feedstock with oxidative leaching comprises treating the ferronickel alloy feedstock at atmospheric pressure in a vessel, such as a column.

[0111] 41. Treating a ferronickel alloy feedstock with oxidative leaching providing a peroxide treatment comprising treating a ferronickel alloy feedstock in the presence of a peroxide; providing a POX process comprising treating a ferronickel alloy feedstock with POX; The process of any one of embodiments 38 to 40, comprising:

[0112] 42. The process of any one of embodiments 35-41, further comprising removing impurities from the leached material.

[0113] 43. The process of any one of embodiments 35-42, wherein the nickel product comprises nickel sulfate, nickel sulfate and cobalt sulfate co-crystallized material, or battery grade nickel material.

[0114] 44. The process of any one of embodiments 35-43, wherein recovering the nickel product comprises crystallization, precipitation, or electrowinning.

[0115] 45. The process of embodiment 44, wherein the crystallizing comprises crystallizing uncrystallized nickel sulfate from the leached material to form crystallized nickel sulfate in the mother liquor.

[0116] 46. ​​The process of embodiment 45, further comprising separating the crystallized nickel sulfate from the mother liquor.

[0117] 47. The process of embodiment 46, wherein the mother liquor contains residual non-crystallized nickel sulfate, further comprising basifying a portion of the mother liquor to convert the non-crystallized nickel sulfate to a basic nickel salt.

[0118] 48. The process of embodiment 47, further comprising using a basic nickel salt upstream of the crystallization of the nickel salt.

[0119] 49. The process of embodiment 48, wherein using the basic nickel salt upstream comprises converting the basic nickel salt back to uncrystallized nickel sulfate.

[0120] 50. A process for the production of nickel products from ferronickel that serves to minimize residues and environmental impacts by producing a usable hematite product from the ferric salts, a saleable potassium sulfate product from the sulfate salts, and a combined concentrated impurity stream that is used as an input for other metallurgical processes.

[0121] The embodiments described herein are intended to be examples only. Changes, modifications, and variations can be made to the specific embodiments by those skilled in the art. The scope of the claims should not be limited by the specific embodiments set forth herein, but should be interpreted in a manner consistent with the present specification as a whole.

[0122] All publications, patents, and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains, and are hereby incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

[0123] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be apparent to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A process for refining a ferro-nickel alloy, comprising: treating the ferronickel alloy with oxidative leaching; The process of treating the ferronickel alloy includes adding a copper reagent and treating the ferronickel alloy in the presence of copper from the copper reagent.

2. Treating the ferronickel alloy with the oxidative leaching comprises: treating the ferronickel alloy with pressure oxidation (POX) leaching; treating the ferro-nickel alloy in the presence of a peroxide; or treating said ferronickel alloy in the presence of sulfuric acid; The process of claim 1 , comprising:

3. 2. The process of claim 1, wherein treating the ferronickel alloy with the oxidative leaching comprises treating the ferronickel alloy in a vessel at atmospheric pressure.

4. Treating the ferronickel alloy with the oxidative leaching comprises: providing a peroxide treatment comprising treating the ferro-nickel alloy in the presence of peroxide and sulfuric acid to provide an effluent; providing a POX process comprising treating said effluent with said POX; The process of claim 2, comprising:

5. 10. The process of claim 1, wherein the copper is provided as copper sulfide, copper oxide, or copper sulfate.

6. Treating the ferronickel alloy with the oxidative leaching comprises: providing said peroxide treatment comprising treating said ferronickel alloy in the presence of a peroxide to provide a first effluent; providing a POX process comprising treating said ferronickel alloy with said POX to provide a second effluent; returning at least a portion of said second effluent to said peroxide treatment. The process of claim 4, comprising:

7. 7. The process of claim 6, wherein returning the second effluent to the peroxide treatment enhances the concentration of nickel in the peroxide treatment.

8. 7. The process of claim 6, wherein returning the second effluent to the peroxide treatment adjusts the pH of the peroxide treatment.

9. 2. The process of claim 1, wherein producing the iron product comprises producing hematite, jarosite, or goethite.

10. 10. The process of claim 9, wherein producing the iron product comprises selectively removing iron in the form of hematite by pressure oxidation (POX) of the ferronickel alloy.

11. The process of claim 1, further comprising a copper recovery step after the oxidative leaching to recover at least a portion of the copper from the copper reagent when the ferro-nickel alloy is treated in the presence of copper.

12. 12. The process of claim 11, wherein the copper recovery step comprises a solvent extraction step, an electrowinning step, a cementation step, a sulfidation step, a pH adjustment step, an ion exchange step, or a pressure oxidation step.

13. 13. The process of claim 12, wherein the copper recovery step comprises a cementation step, wherein a portion of a ferro-nickel alloy or nickel powder is provided to cement the copper from the copper reagent.

14. The process of claim 11, wherein at least a portion of the recovered copper from the copper reagent is returned to a pre-leaching step upstream to the step of treating the ferronickel alloy with oxidative leaching or upstream of the oxidative leaching treatment step.

15. 2. The process of claim 1, wherein the copper is added to the process during the oxidative leaching, the copper cementation step, or a pre-leaching step upstream of the oxidative leaching.

16. 2. The process of claim 1, wherein the oxidative leaching provides an effluent comprising uncrystallized metal sulfates, and producing the nickel product further comprises crystallizing the uncrystallized metal sulfates to form crystallized nickel sulfate or co-crystallized nickel and cobalt sulfates in a mother liquor.

17. 17. The process of claim 16, further comprising separating the crystallized nickel sulfate or co-crystallized nickel and cobalt sulfate from the mother liquor, the mother liquor containing remaining non-crystallized metal sulfates, the process further comprising basifying a portion of the mother liquor to convert the remaining non-crystallized metal sulfates to basic metal salts, and using the basic metal salts upstream of the crystallization of the metal sulfates.

18. 20. The process of claim 17, wherein using the basic metal salt upstream comprises converting the basic metal salt back to the non-crystallized metal sulfate.

19. 1. An improved process for direct refining of a ferronickel alloy, said improvement comprising providing copper during leaching of said ferronickel alloy.

20. 20. The method of claim 19, wherein leaching the ferronickel alloy comprises oxidative leaching.

21. 1. A process for producing a nickel product, comprising: treating a ferro-nickel alloy feedstock with oxidative leaching to form a leached material, said leached material comprising nickel and iron; removing at least a portion of the iron from the leached material; and recovering the nickel product. Including, The process of treating the ferronickel alloy feedstock includes adding a copper reagent and treating the ferronickel alloy feedstock in the presence of copper from the copper reagent.

22. The step of treating the ferronickel alloy feedstock with oxidative leaching comprises: treating the ferronickel alloy feedstock with pressure oxidation (POX) leaching; treating said ferronickel alloy feedstock in the presence of a peroxide; or treating said ferronickel alloy feedstock in the presence of sulfuric acid; 22. The process of claim 21 further comprising:

23. Treating the ferronickel alloy feedstock in the presence of a peroxide comprises providing a peroxide treatment comprising treating said ferronickel alloy feedstock in the presence of a peroxide; providing a POX process comprising treating said ferronickel alloy feedstock with said POX; 23. The process of claim 22, comprising:

24. The process of claim 21, wherein recovering the nickel product comprises crystallizing uncrystallized nickel sulfate from the leached material to form crystallized nickel sulfate in a mother liquor, separating the crystallized nickel sulfate from the mother liquor, the mother liquor containing residual uncrystallized nickel sulfate, and basifying a portion of the mother liquor to convert the uncrystallized nickel sulfate to a basic nickel salt.

25. 25. The process of claim 24, further comprising using the basic nickel salt upstream of the crystallization of the nickel salt.

26. 26. The process of claim 25, wherein using the basic nickel salt upstream comprises converting the basic nickel salt back to the uncrystallized nickel sulfate.

27. Treating the ferro-nickel alloy with pressure oxidation (POX) leaching; providing an effluent from said oxidative leaching, said effluent comprising uncrystallized metal sulfate; crystallizing the uncrystallized metal sulfate to form crystallized nickel sulfate or co-crystallized nickel and cobalt sulfate in a mother liquor to produce a nickel product; separating the crystallized nickel sulfate or co-crystallized nickel and cobalt sulfate from the mother liquor; basifying a portion of the mother liquor to convert the remaining uncrystallized metal sulfate salts into basic metal salts; using said basic metal salt upstream of the crystallization of said metal sulfate; The process of claim 1 further comprising:

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