Metal Sulfurization Process

Abstract

The present invention provides a method for producing a metal sulfide containing nickel and / or cobalt, comprising: i. forming an aqueous metal sulfate solution by reacting sulfuric acid with a feedstock containing nickel and / or cobalt in water; ii. crystallizing the metal sulfate from the aqueous metal sulfate solution to form the crystallized metal sulfate in a mother liquor containing the non-crystallized metal sulfate; iii. separating the crystallized metal sulfate from the mother liquor; iv. reacting at least a portion of the non-crystallized metal sulfate with hydrogen sulfide in an acidic aqueous medium to thereby obtain a slurry comprising a solid phase containing a metal sulfide precipitate and an aqueous phase containing one or more impurities and sulfuric acid; and v. separating the solid phase and the aqueous phase.

Description

[Technical Field]

[0001] The present invention relates to a method for treating a metal-containing feed comprising at least one Ni compound and / or at least one Co compound, and further comprising impurities. [Background technology]

[0002] Nickel is an important industrial metal primarily used in the production of stainless steel, non-ferrous corrosion-resistant alloys, electroplating, and steel alloys. High-purity nickel is essential for the development of a variety of applications. Nickel with purity greater than 98% is obtained by refining nickel ore resources, such as nickel sulfide ore and nickel oxide ore. These ores often also contain a certain amount of iron. Cobalt is also an important industrial metal primarily used in alloys, battery materials, catalyst materials, and pigments.

[0003] The dwindling availability of high-purity nickel resources necessitates new processes and refineries for refining nickel-containing materials. Similarly, the procurement of cobalt is constrained by limited natural production, primarily in politically unstable regions. Such nickel and cobalt refineries must enable high-capacity, highly efficient processes to obtain elemental nickel and / or cobalt, or nickel and / or cobalt compounds, in desired quantities and with high purity. Sulfidation of Ni and / or Co from laterite ore or battery scrap materials, among other processes, is considered one of the more promising routes.

[0004] In this regard, Liu S. et al. have provided an effective method for robust recovery of Ni from laterite ore by H2 reduction using sodium thiosulfate (Na2S2O3) as a promoter. Using 20 wt% Na2S2O3 at 1100°C, a Ni content of 9.97% and a Ni recovery rate of 99.24% were found to be achieved. (2021) A Robust Recovery of Ni From Laterite Ore Promoted by Sodium Thiosulfate Through Hydrogen-Thermal Reduction. Front. Chem. 9:704012. doi:10.3389 / fchem.2021.704012.

[0005] Chinese Patent No. 113 802 002 discloses a method for recycling valuable metals in lithium batteries using a wet process. According to this method, waste lithium battery powder is selectively leached under pressurized hydrogen sulfide gas, resulting in Mn, Li, and Al metal ions entering the first-stage leachate, while nickel, cobalt, copper, and iron exist in the sulfide form in the first-stage leach residue. Only a small amount of sulfuric acid is consumed during the process, and the pH value of the first-stage leachate is then adjusted to remove aluminum and manganese. Following the first-stage leaching process, this method requires an elaborate purification procedure to obtain high-purity Ni. Summary of the Invention [Problem to be solved by the invention]

[0006] Furthermore, there is a need for new methods to obtain nickel and / or cobalt with high purity and high efficiency in energy and material use. [Means for solving the problem]

[0007] The present invention provides a solution to at least one of the above-mentioned problems by providing a method for treating a metal-containing feed as set forth in claim 1. The sulfidation reaction in step iv of the method advantageously proceeds in the presence of a mineral acid. Such mineral acid may be added as such or may be generated in situ from the reaction of NiSO4, NiCl2, CoSO4, or CoCl2 with a sulfiding agent such as hydrogen sulfide in the aqueous reaction medium. Advantageously, such an embodiment increases the total amount of Co and / or Ni in the aqueous medium, thereby improving recovery efficiency. The process is robust enough to handle Co and / or Ni-containing solutions from impure waste streams. In a particularly preferred embodiment, the mineral acid is generated in situ by introducing NiSO4- or CoSO4-containing bleed from a NiSO4 or CoSO4 crystallization unit, respectively, or from a mixed sulfate crystallization unit. DETAILED DESCRIPTION OF THE INVENTION

[0008] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art to which this invention belongs. By way of further guidance, definitions of terms are included to better understand the teachings of the present invention. As used herein, the following terms have the following meanings: As used herein, "a," "an," and "the" refer to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more compartments.

[0009] As used herein, "about" referring to a measurable value such as a parameter, amount, duration, etc., is meant to encompass a variation of no more than ±20%, preferably no more than ±10%, more preferably no more than ±5%, even more preferably no more than ±1%, and still more preferably no more than ±0.1% from the specified value, provided such variation is appropriate for the practice of the disclosed invention, although it should be understood that the value referred to by the modifier "about" is itself specifically disclosed.

[0010] As used herein, "comprise," "comprising," "comprises," and "comprised of" are synonymous with "include," "including," "includes," or "contain," "containing," "contains," and are inclusive or open-ended terms that specify the presence of what follows, e.g., a component, and do not exclude or preclude the presence of additional, unlisted components, features, elements, materials, steps, or elements that are known in the art or disclosed therein.

[0011] The recitation of numerical ranges by endpoints includes not only the recited endpoints but also all numbers and fractions subsumed within that range. All percentages, unless otherwise defined or unless a different meaning is apparent to one of ordinary skill in the art from their use and the context in which they are used, are understood to be percent by weight, abbreviated as "wt %," or percent by volume, abbreviated as "vol %." Unless otherwise specified, weight percent of an element or compound is calculated based on the dry weight of the compound or composition containing that element or compound.

[0012] In the context of the present invention, the term "feedstock" refers to one or more feedstocks containing any one or combination of nickel, cobalt, manganese, or lithium. In some embodiments, the feedstock may include any one or combination of raw materials and recycled materials. Examples of feedstocks include, but are not limited to, mixed hydroxide precipitate (MHP), mixed sulfide precipitate (MSP), nickel sulfide concentrate, cobalt sulfide concentrate, nickel laterite, nickel matte, or ferronickel. Examples of recycled materials include, but are not limited to, spent cathode material and materials derived from recycled lithium-ion batteries or lithium-ion battery manufacturing scrap (collectively referred to herein as black mass).

[0013] In the context of the present invention, the term "MHP" is considered an abbreviation of the term "mixed hydroxide precipitate." Mixed hydroxide precipitate (MHP) is an intermediate product of nickel metallurgy obtained from the processing of laterite ore, which contains mainly nickel and small amounts of cobalt. MHP is a solid product that is typically prepared by extracting nickel and cobalt from laterite ore. Alternatively or additionally, MHP can be obtained from nickel- and / or cobalt-containing hydroxide material generated as manufacturing waste during the preparation of cathode materials, or from nickel- and / or cobalt-containing hydroxide material obtained from battery recycling processes.

[0014] In the context of the present invention, the term "CHIP" is considered an abbreviation of the term "cobalt hydroxide intermediate precipitate." Cobalt hydroxide intermediates consist primarily of cobalt and typically have a cobalt content of 25% to 40% by weight, based on the total weight of the intermediate product. Typically, CHIP also contains a significant amount of nickel. CHIP is known to be very low in impurities, making it ideal for the process of the present invention.

[0015] In the context of the present invention, the term "solid metal-containing feed", specifically the solid metal-containing feed fed to the process in step iv, refers to a solid feed comprising an MHP product, a CHIP product, or a mixture of two or more MHP products, two or more CHP products, or one or more MHP products and one or more CHP products. Preferably, the metal-containing feed comprises at least one Ni compound and / or at least one Co compound. Preferably, the Ni compound and the Co compound are present as Ni(II) compounds and Co(II) compounds, respectively. Furthermore, the Ni compound and the Co compound may be present in a higher oxidation state, such as 3+ or 4+, or the metal-containing feed may comprise a mixture of Ni compounds and / or Co compounds in the oxidation state 2+ and Ni compounds and / or Co compounds in the oxidation states 3+ and / or 4+.

[0016] In the context of the present invention, the term "continuous process" is considered to be a process in which the solution produced has a substantially constant composition. Specifically, a continuous process is one in which the solution produced has a constant composition within what is considered normal process variation. More specifically, the solution produced has a composition in which the concentration of each component is within ±20% or less of its average concentration, preferably ±10% or less, more preferably ±5% or less, and even more preferably ±3% or less. In a preferred embodiment, the present invention provides a continuous process operating under steady-state conditions.

[0017] In the context of the present invention, the term "aqueous medium" is used for an aqueous solution. The aqueous medium facilitates handling of the reactor contents, such as mixing or pumping. The aqueous medium may already contain other components participating in the reaction, or may be added later. The aqueous medium may contain, in particular, a mineral acid.

[0018] Preferably, the mineral acid, such as sulfuric acid or hydrochloric acid, is fed intermittently or gradually to the process according to the invention. The solid metal-containing feed can be fed intermittently or gradually to the process. Furthermore, the solid metal-containing feed is preferably fed only at an early stage of the process.

[0019] The sulfurizing agent used in the sulfurization reaction of step iv must be clearly reactive with Co and / or Ni oxides. Therefore, a suitable sulfurizing agent is preferably at least partially soluble in an aqueous medium. Preferably, the sulfurizing agent, such as HS or NaHS, is supplied to the process according to the present invention at a substantially constant concentration and flow rate. Preferably, the supply rate of the sulfurizing agent to the process is controlled within ±20% or less of the supply rate, preferably ±10% or less, more preferably ±5% or less, and even more preferably ±3% or less.

[0020] In a first aspect, the present invention provides a method for producing metal sulfides comprising nickel and / or cobalt, the method comprising: i. forming an aqueous metal sulfate solution by reacting sulfuric acid with a raw material feed comprising nickel and / or cobalt in water; ii. crystallizing the metal sulfate from the aqueous metal sulfate solution to form a crystallized metal sulfate in a mother liquor containing uncrystallized metal sulfate; iii. separating the crystallized metal sulfate from the mother liquor; iv. reacting at least a portion of the uncrystallized metal sulfate with a sulfiding agent, preferably hydrogen sulfide, in an acidic aqueous medium, thereby obtaining a slurry consisting of a solid phase containing a metal sulfide precipitate and an aqueous phase containing one or more impurities and sulfuric acid; and v. separating the solid phase and the aqueous phase, thereby obtaining a solid phase containing metal sulfides and an aqueous phase.

[0021] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the aqueous medium in step iv further comprises a solid metal-containing feed comprising a nickel compound and / or a cobalt compound. Preferably, the solid metal-containing feed is provided as a solid or as a slurry, i.e., as a solid in an aqueous medium. Preferably, the solid metal-containing feed is composed of MHP material and / or CHIP material. In one embodiment, the raw material feed consumed in step i may have the same composition as the solid metal-containing feed. In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, further comprising, in step iv, adding a basic salt of Li, Na, K, Ca, Mg, Al, Fe, B, Mn, W, and / or U to the aqueous medium. Suitable basic salts include, but are not limited to, MHP, CHIP, Mn carbonate, Mg oxide, battery scrap material, etc.

[0022] The sulfiding reaction in step iv produces a mineral acid that can be advantageously used to simultaneously achieve leaching of impurities in the solid metal-bearing feed. For example, Na or K impurities can be leached with sulfuric acid to produce water-soluble Na or K sulfates, respectively. Such mineral acids can be added neat to facilitate leaching of the impurities, or can be generated in situ from the reaction of NiSO4, NiCl2, CoSO4, or COCl2 with a sulfiding agent, such as hydrogen sulfide, in an aqueous reaction medium according to one or more of the following reactions:

[0023]

number

[0024] Similarly, Ni and / or Co phosphates, nitrates, etc. can be used to generate mineral acid in situ. Contacting NiSO4 or NiCl2 with HS precipitates metal sulfides, such as NiS and / or CoS, and generates mineral acid, sulfuric acid, or hydrochloric acid, respectively, in situ. Advantageously, such embodiments increase the total amount of Co and / or Ni in the aqueous medium, thereby improving recovery efficiency. The process is robust enough to handle Co and / or Ni-containing solutions from impure waste streams. In a particularly preferred embodiment, mineral acid is generated in situ by introducing NiSO4- or CoSO4-containing bleed from a NiSO4 crystallization unit or a CoSO4-containing bleed from a mixed sulfate crystallization unit, respectively.

[0025] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the metal sulfide precipitate obtained in step iv is subsequently leached with an acid and / or an oxidizing agent to regenerate hydrogen sulfide, and the regenerated hydrogen sulfide is used in step iv.

[0026] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the uncrystallized metal sulfate is reacted with hydrogen sulfide in step iv at a temperature of from 25°C to 80°C, preferably at a temperature of from 40°C to 80°C, more preferably at a temperature of about 60°C.

[0027] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the uncrystallized metal sulfate is reacted in step iv with hydrogen sulfide under atmospheric pressure.

[0028] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein at least a portion of the uncrystallized metal sulfate is reacted in step iv with hydrogen sulfide in an acidic aqueous medium at a pH of 1.5 to 10, preferably a pH of 1.5 to 6, more preferably a pH of 3 to 6. Preferably, the acidic aqueous medium comprises sulfuric acid.

[0029] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein prior to step ii, the amount of impurities in the aqueous metal sulfate solution is reduced by precipitation, ion exchange and / or extraction of impurities from the aqueous metal sulfate solution. Preferably, at least a portion of the mother liquor obtained in step iii is basified to form a basic metal salt. Preferably, the basic metal salt is used in one or more of the aforementioned precipitation, ion exchange and extraction steps, such as for the preparation of an extractant pre-loaded with nickel and / or cobalt.

[0030] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein step iv comprises reacting the solid metal-containing feed in an aqueous medium with a sulfiding agent at a pH of 1.5 to 10, thereby obtaining a slurry comprising a solid phase enriched in Ni and / or Co and an aqueous phase comprising water-soluble salts of one or more of Li, Mn, Mg, Al, Fe, Ca, B, Na, and / or U. The pH of the aqueous medium can be controlled by adding a mineral acid, such as sulfuric acid or hydrochloric acid. Preferably, the present invention provides a method wherein the solid metal-containing feed is first reacted with a sulfiding agent in step iv at a pH of 3.0 to 10, and then the pH of the aqueous medium is lowered to a pH below 3.0. Because sulfidation proceeds kinetically faster at higher pHs, preferably at a pH of 6.5 to 8.0, it is advantageous to carry out the first sulfidation at a maximum pH of 10. Furthermore, at higher pHs, impurities such as Na, Mg, and Ca can already be removed from the feed. It has been found that lowering the pH in the second sulfurization step to a value below 3.0, preferably below 2.5, is advantageous for dissolving all impurities such as Fe, Al, Si, and U. More preferably, the pH of the aqueous medium is lowered to a pH of 1.5 to 2.5. It is equally possible to lower the pH further to a pH value below 1.5. Preferably, the sulfurization reaction of step iv is carried out in a closed reactor to avoid the emission of harmful gases. Preferably, the reactor off-gas is recycled to the reactor feed.

[0031] In a preferred embodiment, the present invention provides a mineral acid solution containing a mineral acid having a pH of 3 to 10 in an aqueous medium having a pH of less than 3.0, wherein the volume ratio φ AC is 0.0 to 0.95. AC is 0.10 to 0.95, and more preferably, the ratio φ AC is about 0.80, 0.85, 0.90, or 0.95, or any value therebetween.

[0032] It is therefore also expected to provide a process capable of selectively leaching impurities such as Li, Mg, and Mn from feed materials containing Ni and / or Co. Other impurities typically found in such solid metal-bearing feeds include, but are not limited to, Al, Fe, Ca, B, Na, and U. Other impurities, such as, but not limited to, Zn and Cu, do not form water-soluble salts in the process environment and therefore tend to remain in the solid phase. Such impurities can be separated from the Ni and / or Co in state-of-the-art refining processes. Additionally, organic carbon present in metal feeds may be washed away as water-soluble compounds and recovered in the aqueous phase.

[0033] Generally, refining process flowsheets for MHP and / or CHIP refining of Ni and / or Co rely on the extraction of impurities such as Mn and Mg from solution. This method provides an alternative method for removing Mg and Mn from Ni.

[0034] Other elements also removed through the formation of water-soluble salts are Al, Fe, U, Na, B, Ca, and U. Many additional impurities that may be present in the feed, such as F, W, Si, P, C, K, Fe, Cl, and SO4, will be recovered in the aqueous phase. Other impurities, such as Cu, Zn, Pb, and Cd, are reported in the solid residue. The production of a solid residue containing Mn-depleted Co and / or Ni sulfides offers several advantages to the hydrometallurgical refining process: the Mn does not dilute the Ni and / or Co-containing solution, and there is no need to isolate the Mn by solvent extraction, etc., allowing for a more robust process.

[0035] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the solid phase containing Ni(II) sulfides and / or Co(II) sulfides obtained in step ii is leached with an acid and / or an oxidizing agent (such as, but not limited to, O or Cl). In this way, a high-purity Ni salt and / or Co salt solution can be obtained, while the sulfiding agent can be regenerated and recycled to step iv of the method of the present invention. Leaching NiS and CoS with acid leads to the formation of Ni salts and Co salts, respectively, and the formation of H2S. For example, the reaction of NiS with sulfuric acid leads to the formation of NiSO4 and H2S, which can be advantageously recycled as a sulfiding agent in step iv. Similarly, the reaction of NiS with oxygen and HCl or chlorine gas leads to the formation of NiCl2 and S. S can be advantageously reduced to a sulfiding agent, such as H2S, which can be recycled as a sulfiding agent in step iv.

[0036] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the solid metal-containing feed in the aqueous medium is first reacted with the sulfiding agent in step iv at a pH of 3.0 to 4.5. It has been found that a lower pH promotes leaching of impurities from the solid metal-containing feed and increases the process rate. However, sulfidation at too low a pH is not sufficiently selective. The inventors have found that optimal process conditions are obtained when the first sulfiding reaction is carried out at a pH of about 3.0 to 4.5. Preferably, the first sulfiding step is carried out for a treatment time of 2 to 16 hours, preferably 4 to 12 hours, and more preferably 4 to 10 hours.

[0037] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the metal-containing feed is reacted at a pH of 3.0 to 10, and then the pH of the aqueous medium is lowered to a pH of 1.5 to 3.0. Lowering the pH has been found to increase the rate of the process. It has also been found that lowering the pH below 1.5 further improves impurity removal, but does not fully recover the cost of the mineral acid consumed in the process. The inventors have found that optimal process conditions are obtained when the second sulfurization reaction is carried out at a pH of about 2.0 to 3.0, most preferably 2.1, 2.2, 2.3, 2.4, or 2.5, or any value therebetween. Preferably, the second sulfurization step is carried out for a treatment time of 0.5 to 8 hours, preferably 1 to 4 hours, more preferably 1 hour, 2 hours, 3 hours, 4 hours, or any value therebetween.

[0038] Multi-step processes are advantageous when most of the process is carried out at a pH between 3.2 and 6.0, or 3.5 and 6.0, with the pH lowered to 1.5 to 3 in the second or subsequent addition steps. The rate of sulfide formation is enhanced at higher pHs. For this reason, it is advantageous to conduct most of the process at a relatively high pH, ​​since sulfide formation becomes the rate-limiting step. In the second or subsequent addition steps, a lower pH is selected to maximize dissolution of Mn and other impurities. After each such addition step, a solid-liquid separation can optionally be performed. The majority of the conversion to sulfide typically occurs in the first reaction step, and is then completed in the second or subsequent addition step. Because sulfide formation does not occur below pH 1, the process must be completed at a pH between 1 and 5. Operating above the upper pH limit results in insufficient Mn dissolution.

[0039] After the process is complete, the pH can be further reduced to below 1.5 to maximize the removal of impurities. Indeed, the metal sulfides formed do not redissolve in the absence of an oxidizing agent, but some impurities can be removed from the residue.

[0040] The solid residue obtained in step v of separating the solid from the solution, containing a majority of the Co and / or Ni as Co and / or Ni sulfides, can be further processed in different ways: hydrometallurgical processing of the solid residue is the preferred option.

[0041] Thus, in a further embodiment, a process is described in which the solid residue is used as a starting material in a subsequent hydrometallurgical refining process. - leaching the solid residue containing Co and / or Ni sulfides with a mineral acid, preferably H2SO4, thereby obtaining a Ni and / or Co containing solution, - separating the solution from the insoluble solids, under the condition that the insoluble solids remain; and - crystallizing Ni and / or Co from the Ni and / or Co containing solution, preferably as Ni sulphate and / or Co sulphate.

[0042] In a preferred embodiment, the present invention provides a process according to the first aspect of the present invention, wherein the solid metal-containing feed is reacted with the sulfiding agent in step iv at a temperature of 20°C to 80°C, preferably 25°C to 80°C. Preferably, the feed is reacted with the sulfiding agent at a substantially constant temperature. Because the reaction is moderately exothermic, heating may only be required in the early stages of the process. In a preferred embodiment, the temperature is controlled to a temperature below 80°C, preferably between 40°C and 80°C, more preferably at about 60°C. Avoiding excessively high reaction temperatures can increase the solubility of HS in aqueous media, thereby accelerating the rate of the sulfiding reaction.

[0043] In a preferred embodiment, the present invention provides a process according to the first aspect of the present invention, wherein the solid metal-containing feed is reacted with the sulfiding agent in step iv at atmospheric pressure, i.e., 1 bar, or at a low pressure of less than 0.3 bar, preferably less than 0.2 bar, more preferably less than 0.1 bar. Working at low pressure conditions ensures that the H2S used in the process does not leak into the environment. Preferably, the process proceeds in an oxygen- or air-free atmosphere. In a preferred embodiment, the gaseous atmosphere above the aqueous medium is flushed with an inert gas such as N2. By carrying out the process without oxidizing agents such as oxygen and air, unwanted oxidation of nickel sulfide and / or cobalt sulfide can be avoided.

[0044] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein hydrogen sulfide in step iv is replaced with NaHS, KHS, or LiHS. H2S and NaHS are preferred sources of sulfide. Most preferably, the sulfiding agent comprises H2S. H2S can be introduced directly into the aqueous medium or can be generated in situ by adding elemental sulfur under reducing conditions, more specifically, in the presence of H2. In the present invention, the sulfiding agent not only acts as a precipitant to form metal sulfides but also advantageously acts as a reducing agent for high-valent metals in oxidation states such as 3+ or 4+. The amount of sulfiding agent added is preferably sufficient to saturate the slurry with H2S. Saturation can be easily confirmed by monitoring the rate of absorption of H2S by the reaction mixture. Saturation provides the optimum rate. Alternatively or additionally, NaHS can be introduced as the sulfiding agent. Ammonium sulfide can also be used.

[0045] Suitable sulfiding agents are preferably at least partially soluble in aqueous media. For example, LiS reacts with the slurry to form a soluble Li salt and a soluble sulfide. On the other hand, sulfides that are insoluble under the described conditions, such as CuS, are not considered suitable sources of sulfide, i.e., sulfiding agents, respectively, according to the present invention.

[0046] The mineral acid is preferably selected from the list consisting of H2SO4, HCl, H3PO4, and HNO3, or mixtures thereof. In a preferred embodiment, the invention provides a method according to the first aspect of the invention, wherein the mineral acid is sulfuric acid. Alternatively, the mineral acid may be hydrochloric acid.

[0047] In a preferred embodiment, the present invention provides a method according to the first aspect of the invention which is a continuous process, in particular the method is carried out under continuous flow conditions.

[0048] In a preferred embodiment, the present invention provides a process according to the first aspect of the present invention, wherein the solid metalliferous feed in step iv comprises Ni and / or Co in an amount of 5 to 75 wt%, preferably 10 to 65 wt%, based on the total weight of the solid metalliferous feed. Preferably, the solid metalliferous feed comprises Ni and / or Co in an amount of 20 to 60 wt%, such as 30 to 50 wt%.

[0049] In an alternative embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the solid metal-containing feed in step iv comprises lithium-free battery material, such as non-lithiated manufacturing waste material obtained from battery manufacturing, or partially recycled battery material from which its lithium content has been removed. In addition to oxides of Co and / or Ni, a typical battery scrap-based feed may also contain anode materials such as carbon, electrode foil, and electrolyte. Preferably, at least the majority of the Co and / or Ni contained in the feed, more preferably at least 80 wt.%, and most preferably at least 90 wt.%, is in the form of the respective metal oxide. The remainder may comprise Co and / or Ni in metallic form.

[0050] In a preferred embodiment, the present invention provides a process according to the first aspect of the present invention, wherein the solid metalliferous feed in step iv comprises Ni in an amount of 10 to 70 wt%, preferably 20 to 60 wt%, more preferably 30 to 55 wt%, based on the total weight of the solid metalliferous feed. Preferably, the solid metalliferous feed further comprises Co in an amount of 0.5 to 15 wt%, preferably 1 to 10 wt%, more preferably 1 to 5 wt%, based on the total weight of the solid metalliferous feed.

[0051] In a preferred embodiment, the present invention provides a process according to the first aspect of the present invention, wherein the Ni and / or Co compounds present in the solid metal-containing feed in step iv are in the oxidation state 2+. Furthermore, the process of the present invention also enables the Ni and Co compounds to include compounds in higher oxidation states, such as 3+ or 4+. Preferably, the compounds are water-insoluble compounds. Advantageously, it has been found that under the reaction conditions of the present invention, Ni and / or Co metal compounds having higher oxidation states are efficiently reduced by a sulfiding agent, preferably HS, during the first step of the process of the present invention.

[0052] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the Ni compounds and / or at least one Co compound in the solid metal-containing feed in step iv comprises carbonates, hydroxycarbonates, sulfates, sulfites, phosphates, hydroxides, and / or oxides. Preferably, the Ni compounds and / or at least one Co compound in the solid metal-containing feed are composed of hydroxycarbonates, hydroxides and / or oxides, most preferably hydroxycarbonates and / or hydroxides.

[0053] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the solid metalliferous feed in step iv comprises Mn in an amount of 1 to 15 wt.%, preferably in an amount of 3 to 10 wt.%, relative to the total weight of the solid metalliferous feed.

[0054] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein the solid metalliferous feed in step iv comprises Mg in an amount of 0.1 to 10 wt.%, preferably in an amount of 1 to 7 wt.%, relative to the total weight of the solid metalliferous feed.

[0055] In a preferred embodiment, the present invention provides a process according to the first aspect of the present invention, wherein the solid metalliferous feed in step iv comprises Al in an amount of 0.01 to 2.00 wt.%, preferably 0.02 to 1.50 wt.%, relative to the total weight of the solid metalliferous feed.

[0056] In a preferred embodiment, the present invention provides a process according to the first aspect of the present invention, wherein the solid metalliferous feed in step iv further comprises Cu in an amount of 0.01-0.20 wt. %, relative to the total weight of the solid metalliferous feed, and / or Zn in an amount of 0.2-1.0 wt. %, relative to the total weight of the solid metalliferous feed.

[0057] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the solid metal-containing feed in step iv is a powder, preferably having a D50 of less than 100 μm, as measured according to ASTM B822-97 Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by Light Scattering, American Society for Testing and Materials, West Conshohocken, PA (1997). ASTM B822-97 is the ASTM Standard Test Method for Particle Size Measurement of Particulate Metals and Compounds by Laser Diffraction. Preferably, the powder has a D50 of less than 50 μm, more preferably less than 30 μm, and greater than 0.1 μm, more preferably greater than 1 μm. Metal oxides are more reactive when present in powder form. Therefore, average particle sizes of less than 100 μm, less than 50 μm, or even less than 30 μm are preferred in industrial settings. Such powders need not be dry powders but can be derived from wet processes, such as filter cakes. This is particularly advantageous since the formation of Ni and Co sulfides has been found to be the rate-limiting step.

[0058] In a further embodiment, the method according to the first aspect of the present invention is carried out in a continuous operation. In such a setup, the feed and acid are continuously added to the reactor while the slurry is extracted from the reactor. The addition and extraction can also be carried out in a batch mode, for example, repeated every 30 minutes. Continuous operation has several advantages. First, continuous operation enhances the use of reactor equipment. Second, the solid Co and / or Ni sulfides are formed at a steady state, resulting in more consistent quality, which facilitates further refinement. In an alternative embodiment, the method according to the first aspect of the present invention is carried out in a batch mode. In such an operation, the first stage of the sulfurization process is carried out in a first reactor at a pH between 3.0 and 10.0, and the second stage of the process is carried out in a second, separate reactor at a pH below 3.0.

Claims

1. 1. A method for producing metal sulfides containing nickel and / or cobalt, comprising: i. forming an aqueous metal sulfate solution by reacting sulfuric acid with a raw material feed comprising nickel and / or cobalt in water, wherein the metal sulfate comprises nickel and / or cobalt sulfate; ii. Crystallizing the metal sulfate from the aqueous metal sulfate solution to form a crystallized metal sulfate in a mother liquor containing uncrystallized metal sulfate; iii. Separating the crystallized metal sulfate from the mother liquor; iv. reacting at least a portion of the non-crystallized metal sulfate with a sulfiding agent in an acidic aqueous medium, thereby obtaining a slurry consisting of a solid phase containing a metal sulfide precipitate and an aqueous phase containing one or more impurities and sulfuric acid; v. Separating the solid phase and the aqueous phase, thereby obtaining a solid phase containing metal sulfides including nickel and / or cobalt, and an aqueous phase; In step iv, a solid metal-containing feed comprising a nickel compound and / or a cobalt compound is added to the aqueous medium; The method of claim 1, wherein the Ni and / or Co in the solid metal-containing feed in step iv is configured as carbonates, hydroxycarbonates, sulfates, phosphates, hydroxides, and / or oxides.

2. 2. The method of claim 1, further comprising adding a basic salt of Li, Na, K, Ca, Mg, Al, Fe, B, Mn, W and / or U to the aqueous medium in step iv.

3. 2. The method of claim 1, wherein the metal sulfide precipitate obtained in step iv is subsequently leached with an acid and / or an oxidizing agent to regenerate hydrogen sulfide, and the regenerated hydrogen sulfide is used in step iv.

4. 2. The method of claim 1, wherein the uncrystallized metal sulfate is reacted with a sulfiding agent in step iv at a temperature of 40°C to 80°C.

5. 2. The method of claim 1, wherein the uncrystallized metal sulfate is reacted with a sulfiding agent in step iv at atmospheric pressure.

6. 2. The method of claim 1, wherein at least a portion of the uncrystallized metal sulfate is reacted with a sulfiding agent in step iv in an aqueous medium having a pH of 1.5 to 6.

7. 7. The method of claim 6, wherein sulfuric acid is added to the aqueous medium in step iv.

8. 2. The method of claim 1, wherein prior to step ii, the amount of impurities in the aqueous metal sulfate solution is reduced by precipitation, ion exchange, and / or extraction of impurities from the aqueous metal sulfate solution.

9. 2. The method of claim 1, wherein the solid metalliferous feed in step iv comprises Ni and / or Co in an amount of 5 to 75 wt. %, based on the total weight of the solid metalliferous feed.

10. 2. The method of claim 1, wherein the Ni and / or Co in the solid metal-containing feed in step iv is configured as hydroxides.

11. 2. The method of claim 1, wherein the solid metalliferous feed in step iv comprises Mn in an amount of 1 to 15 wt. %, based on the total weight of the solid metalliferous feed.

12. 2. The method of claim 1, wherein the solid metalliferous feed in step iv comprises Mg in an amount of 0.1 to 10 wt. %, based on the total weight of the solid metalliferous feed.

13. 2. The method of claim 1, wherein the solid metalliferous feed in step iv comprises Al in an amount of 0.01 to 2.00 wt. %, based on the total weight of the solid metalliferous feed.

14. 2. The method of claim 1, wherein the solid metalliferous feed in step iv further comprises Cu in an amount of 0.01 to 0.20 wt. %, based on the total weight of the solid metalliferous feed, and / or Zn in an amount of 0.2 to 1.0 wt. %, based on the total weight of the solid metalliferous feed.

15. 15. The method of any one of claims 1 to 14, wherein the solid metal-containing feed in step iv is a powder having an average particle size D50 of 0.1 to 100 μm measured according to ASTM B822-97.

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