Method for metal vulcanization

Abstract

The present invention provides a process for producing a metal sulfide comprising nickel and / or cobalt, the process comprising the steps of: 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, the mother liquor comprising 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 hydrogen sulfide in an acidic aqueous medium, thereby obtaining a slurry consisting of a solid phase comprising metal sulfide precipitates and an aqueous phase comprising 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 metalliferous feed comprising at least one Ni compound and / or at least one Co compound, said feed also comprising impurities. Background Art

[0002] Nickel is an important industrial metal, mainly used in stainless steel production, non-ferrous corrosion-resistant alloys, electroplating, and alloy steel. High-purity nickel is necessary for the development of different applications. Nickel with a purity of more than 98% can be obtained from refined nickel ore resources such as nickel sulfide ores and nickel oxide ores. Usually, these ores also contain a certain amount of iron. In addition, cobalt is an important industrial metal, mainly used in alloys, battery materials, catalyst materials and pigments.

[0003] Due to the reduced availability of high-purity nickel resources, new methods and refineries for purifying nickel-containing materials are needed. Similarly, the source of cobalt is subject to limited natural existence and is mainly obtained from politically unstable areas. Such nickel refineries and cobalt refineries will need to provide high-capacity and high-efficiency methods to produce the required amount and high-purity elemental nickel and / or cobalt or nickel and / or cobalt compounds. Among other methods, it is believed that the sulfidation of Ni and / or Co from laterite nickel ore or waste battery materials is one of the more promising routes.

[0004] In this regard, Liu S. et al. provided an effective way to robustly recover Ni from laterite ore by H2 reduction using sodium thiosulfate (Na2S2O3) as a promoter. It was found that 9.97% Ni content and 99.24% Ni recovery were achieved with 20 wt% Na2S2O3 at 1100°C, Liu S. et al. (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] CN 113 802 002 discloses a method for recovering valuable metals in lithium batteries by wet process. According to the method, waste lithium battery powder is selectively leached under the condition of pressurization and introduction of hydrogen sulfide gas, so that Mn, Li and Al metal ions enter the first stage leaching solution, and nickel, cobalt, copper and iron are present in the first stage leaching residue in the form of sulfides. Only a small amount of sulfuric acid is consumed in the process, and then the pH value of the first stage leaching solution is adjusted to remove aluminum and manganese. After the first stage leaching process, the method requires a complex purification procedure to obtain high purity Ni.

[0006] However, new methods are needed to provide nickel and / or cobalt at high purity and efficiency for energy and materials applications. Summary of the invention

[0007] The present invention provides a solution to at least one of the above problems by providing a method for treating a metal-containing feed according to claim 1. The sulfidation reaction in step iv. of the method is advantageously carried out in the presence of an inorganic acid. This inorganic acid can be added as is, or can be generated in situ by the reaction of NiSO4, NiCl2, CoSO4 or CoCl2 with a sulfiding agent such as hydrogen sulfide in an aqueous reaction medium. Advantageously, according to such an embodiment, the total amount of Co and / or Ni in the aqueous medium is increased, which allows to improve the recovery efficiency. The process is robust enough to process Co and / or Ni-containing solutions from impure waste streams. In a particularly preferred embodiment, the inorganic acid is generated in situ by introducing a discharge containing NiSO4 or CoSO4 obtained from a NiSO4 crystallization unit or from a CoSO4 crystallization unit or from a mixed sulfate crystallization unit, respectively. DETAILED DESCRIPTION

[0008] Unless otherwise defined, all terms (including technical and scientific terms) used in disclosing the present invention have the meanings commonly understood by a person of ordinary skill in the art to which the present invention belongs. By way of further guidance, term definitions are included to better understand the teachings of the present invention. As used herein, the following terms have the following meanings:

[0009] As used herein, "a", "an", and "the" refer to both singular and plural references unless the context clearly dictates otherwise. For example, "a compartment" refers to one or more than one compartment.

[0010] As used herein, "about" in reference to a measurable value such as a parameter, amount, time duration, etc., is intended to encompass + / -20% or less, preferably + / -10% or less, more preferably + / -5% or less, even more preferably + / -1% or less, and still more preferably + / -0.1% or less and variations from the specified value, within which such variations are suitable for performing in the disclosed invention. However, it should be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

[0011] As used herein, "comprising," "having," and "consisting of" are synonymous with "including" or "containing" and are inclusive or open-ended terms that specify the presence of subsequent items, such as components, and do not exclude or preclude the presence of additional non-cited components, features, elements, members, steps known in the art or disclosed herein.

[0012] Numerical ranges recited by endpoints include all numbers and fractions contained within the range, as well as the recited endpoints. All percentages are understood to be weight percentages abbreviated as "wt %" or volume percentages abbreviated as "vol %", unless otherwise defined or unless a different meaning is apparent to one skilled in the art from its use and the context in which it is used. Unless otherwise indicated, the weight % of an element or compound is calculated relative to the dry weight of the compound or composition containing the element or compound.

[0013] In the context of the present invention, the term "raw material feed" refers to one or more raw materials comprising any one or a combination of nickel, cobalt, manganese or lithium. In some embodiments, the raw material feed may comprise any one or a combination of raw materials and recycled materials. Examples of raw materials include, but are not limited to, mixed hydroxide precipitates (MHP), mixed sulfide precipitates (MSP), nickel sulfide concentrates, cobalt sulfide concentrates, nickel laterites, nickel matte or nickel iron. Examples of recycled materials include, but are not limited to, spent cathode materials and materials derived from recycled lithium-ion batteries or lithium-ion battery manufacturing waste (collectively referred to herein as black matter).

[0014] In the context of the present invention, the term "MHP" is considered to be an abbreviation of the term "mixed hydroxide precipitate". Mixed hydroxide precipitate (MHP) is an intermediate product of nickel metallurgy obtained by processing laterite ores containing mainly nickel and a small amount of cobalt. MHP is a solid product generally prepared by extracting nickel and cobalt from laterite ores. Alternatively or in addition, MHP can be obtained from hydroxide materials containing nickel and / or cobalt generated as production waste during the preparation of cathode materials or obtained from battery recycling processes.

[0015] In the context of the present invention, the term "CHIP" is considered to be an abbreviation of the term "cobalt hydroxide intermediate precipitation". The cobalt hydroxide intermediate consists mainly of cobalt and generally has a cobalt content of 25% to 40% by weight relative to the total weight of the intermediate product. Typically, the CHIP contains a large amount of nickel. CHIPs are known to have very small amounts of impurities, which makes them attractive for the process according to the present invention.

[0016] In the context of the present invention, the term "solid metal-containing feed", in particular the solid metal-containing feed fed into step iv. of the process, refers to a solid feed comprising an MHP product, a CHIP product, or a mixture of two or more MHP products and two or more CHP products, or a mixture of one or more MHP products and one or more CHIP 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 included as a Ni (II) compound and as a Co (II) compound, respectively. However, the Ni compound and the Co compound included may also be in a higher oxidation state such as 3+ or 4+, or the metal-containing feed may comprise a mixture of Ni and / or Co compounds in the 2+ oxidation state and in the 3+ and / or 4+ oxidation state.

[0017] 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 a process in which the solution produced has a constant composition within the range considered to be normal process variation. More specifically, the solution produced has a composition in which the concentration of each component is within the range of + / -20% or less, preferably + / -10% or less, more preferably + / -5% or less, even more preferably + / -3% or less of its average concentration. In a preferred embodiment, the invention provides a continuous process operating under steady-state conditions.

[0018] In the context of the present invention, the term "aqueous medium" is used for water-based solutions. The aqueous medium facilitates the handling of the reactor contents, such as mixing or pumping. The aqueous medium may already contain some other ingredients that participate in the reaction, or those ingredients may be added later. The aqueous medium may in particular contain a mineral acid.

[0019] Preferably, a mineral acid such as sulfuric acid or hydrochloric acid is fed intermittently or gradually into the process according to the invention. The solid metal-containing feed can be fed intermittently or gradually into the process. However, the solid metal-containing feed is preferably fed only in the initial stages of the process.

[0020] The sulfiding agent used in the sulfiding reaction of step iv. should obviously react easily with oxidized Co and / or Ni. Therefore, a suitable sulfiding agent should preferably be at least partially soluble in an aqueous medium. Preferably, the sulfiding agent such as H2S or NaHS is fed into the process according to the invention at a substantially constant concentration and flow rate. Preferably, the feed rate of the sulfiding agent into the process is controlled within the range of + / -20% or less, preferably + / -10% or less, more preferably + / -5% or less, even more preferably + / -3% or less of its feed rate.

[0021] In a first aspect, the present invention provides a method for producing a metal sulfide comprising nickel and / or cobalt, the method comprising the steps of:

[0022] i. forming an aqueous metal sulfate solution by reacting sulfuric acid with a raw material feed comprising nickel and / or cobalt in water;

[0023] ii. crystallizing the metal sulfate from the aqueous metal sulfate solution to form a crystallized metal sulfate in a mother liquor comprising uncrystallized metal sulfate;

[0024] iii. separating the crystalline metal sulfate from the mother liquor;

[0025] iv. reacting at least a portion of the uncrystallized metal sulfate with a sulfiding agent, preferably hydrogen sulfide, in an acidic aqueous medium to obtain a slurry consisting of a solid phase comprising a precipitate of metal sulfide and an aqueous phase comprising one or more impurities and sulfuric acid; and

[0026] v. separating the solid phase and the aqueous phase, thereby obtaining an aqueous phase and a solid phase comprising metal sulfides.

[0027] 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 containing 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., a solid in an aqueous medium). Preferably, the solid metal-containing feed consists 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, the method further comprising the step of 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. Suitable basic salts are, but are not limited to, MHP, CHIP, Mn carbonate, Mg oxide, waste battery materials, and the like.

[0028] The sulfidation reaction in step iv. produces a mineral acid which can be advantageously used to simultaneously effect leaching of impurities in the solid metalliferous 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 also be added as is to stimulate leaching of impurities, or can be generated in situ by 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:

[0029]

[0030] Similarly, phosphates, nitrates, etc. of Ni and / or Co can be used for in-situ generation of inorganic acid. At NiSO or NiCl When contacting with H S, sulfide metals such as NiS and / or CoS precipitate, and respectively in-situ generation of inorganic acid, i.e., sulfuric acid or hydrochloric acid. Advantageously, according to such an embodiment, the total amount of Co and / or Ni in the aqueous medium increases, which allows to improve recovery efficiency. The process is robust enough to process Co and / or Ni solutions from impure waste streams. In a particularly preferred embodiment, by introducing respectively from NiSO crystallization unit or from CoSO crystallization unit or from mixed sulfate crystallization unit containing NiSO or CoSO The effluent produces inorganic acid in-situ.

[0031] 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 with an oxidant to regenerate hydrogen sulfide, and wherein the regenerated hydrogen sulfide is used in step iv.

[0032] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the uncrystallized metal sulfate is reacted with hydrogen sulfide in step iv. at a temperature between 25°C and 80°C, preferably between 40°C and 80°C, and more preferably at about 60°C.

[0033] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the non-crystallized metal sulfate is reacted with hydrogen sulfide in step iv. at atmospheric pressure.

[0034] In a preferred embodiment, the present invention provides a process according to the first aspect of the invention, wherein at least a portion of the uncrystallized metal sulfate is reacted with hydrogen sulfide in step iv. in an acidic aqueous medium at a pH between 1.5 and 10, preferably at a pH between 1.5 and 6, and more preferably at a pH between about 3 and 6. Preferably, the acidic aqueous medium comprises sulfuric acid.

[0035] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein 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 prior to step ii. Preferably, at least a portion of the mother liquor obtained in step iii. is alkalized to form an alkaline metal salt. Preferably, the alkaline metal salt is used in one or more of the above-mentioned precipitation, ion exchange and extraction steps, such as for preparing an extractant preloaded with nickel and / or cobalt.

[0036] 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 with a sulfiding agent in an aqueous medium at a pH between 1.5 and 10, thereby obtaining a slurry comprising a solid phase rich in Ni and / or Co and an aqueous phase comprising one or more water-soluble salts of Li, Mn, Mg, Al, Fe, Ca, B, Na and / or U. The pH of the aqueous medium can be controlled by adding an inorganic 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 between 3.0 and 10, and wherein the pH of the aqueous medium is subsequently reduced to a pH below 3.0. A first sulfidation at a pH of up to 10 is advantageous because sulfidation proceeds kinetically faster at a higher pH, preferably at a pH of 6.5 to 8.0. In addition, at a higher pH, impurities such as Na, Mg and Ca may have been removed from the feed material. It has been found that lowering the pH to a value below 3.0, preferably below 2.5, in the second sulfiding step 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 between 1.5 and 2.5. It is also possible to further lower the pH to a pH value below 1.5. Preferably, the sulfiding reaction of step iv. is carried out in a closed reactor to avoid the emission of harmful gases. Preferably, the reactor offgas is recycled into the feed to the reactor.

[0037] In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein the volume ratio of the inorganic acid in the aqueous medium having a pH between 3 and 10 to the inorganic acid in the aqueous medium having a pH below 3.0 is AC is between 0.0 and 0.95. Preferably, the ratio φ AC is between 0.10 and 0.95, and more preferably, the ratio φ AC is about 0.80, 0.85, 0.90 or 0.95, or any value therebetween.

[0038] Therefore, it is also desirable to provide a method capable of selectively leaching impurities such as Li, Mg and Mn from a feed material containing Ni and / or Co. Other impurities typically contained in such solid metal-containing 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 under the conditions of the method and therefore tend to remain in the solid phase. Such impurities can be separated from the Ni and / or the Co in a refining process according to the prior art. In addition, organic carbon present in the metal feed can be washed out as a water-soluble compound and will be collected in the aqueous phase.

[0039] Typically, refining process flowsheets for Ni and / or Co MHP and / or CHIP refining rely on extracting impurities such as Mn and Mg from solution. The present method provides an alternative way to remove Mg and Mn from Ni.

[0040] Other elements that are also removed by forming water-soluble salts are Al, Fe, U, Na, B, Ca and U. Many other impurities such as F, W, Si, P, C, K, Fe, Cl, SO4 may be present in the feed material and will be collected in the aqueous phase. Other impurities such as Cu, Zn, Pb and Cd will be reported as solid residues. The generation of a solid residue containing Mn-depleted Co and / or Ni has several advantages for the hydrometallurgical refining process. It makes the process more intensive because Mn does not dilute the solution containing Ni and / or Co and avoids the need to separate Mn, for example, by solvent extraction.

[0041] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the solid phase comprising sulfided Ni(II) and / or sulfided Co(II) obtained in step ii. is leached with an acid and / or an oxidizing agent such as, but not limited to, O2 or Cl2. In this way, a high-purity Ni salt solution and / or Co salt solution can be obtained, while the sulfiding agent can be regenerated and can be recycled to step iv. of the process of the present invention. Leaching NiS and CoS with acid results in the formation of Ni salts and Co salts, respectively, and in the formation of H2S. For example, the reaction of NiS with sulfuric acid results in the formation of NiSO4 and H2S, the latter of which can advantageously be recycled as a sulfiding agent in step iv. Similarly, the reaction of NiS with oxygen and HCl or with chlorine results in the formation of NiCl2 and S. S can advantageously be reduced to provide a sulfiding agent such as H2S, which can be recycled as a sulfiding agent in step iv.

[0042] 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 between 3.0 and 4.5. It has been found that a lower pH is conducive to the leaching of impurities from the solid metal-containing feed and fast process kinetics. However, sulfidation at too low a pH is not sufficiently selective. The inventors have found that when the first sulfidation reaction is carried out at a pH of about 3.0 to 4.5, optimal process conditions are obtained. Preferably, the first sulfidation step is carried out for a treatment time of 2 hours to 16 hours, preferably 4 hours to 12 hours, more preferably 4 hours to 10 hours.

[0043] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein after reacting the metal-containing feed at a pH between 3.0 and 10, the pH of the aqueous medium is reduced to a pH between 1.5 and 3.0. It has been found that reducing the pH is conducive to faster process kinetics. It has also been found that reducing the pH to less than 1.5 further improves the removal of impurities, but will not fully compensate for the cost of inorganic acid consumption in the method. The inventors have found that when the second sulfidation reaction is carried out at a pH of about 2.0 to 3.0, most preferably at a pH of 2.1, 2.2, 2.3, 2.4 or 2.5 or any value therebetween, optimal process conditions are obtained. Preferably, the second sulfidation step is carried out for a treatment time of 0.5 hours to 8 hours, preferably 1 hour to 4 hours, more preferably 1 hour, 2 hours, 3 hours or 4 hours or any period therebetween.

[0044] The multi-step method is advantageous, wherein the majority of the method is carried out at a pH between 3.2 and 6.0, or even at a pH between 3.5 and 6.0, and in the second or any subsequent additional step, the pH is reduced to between 1.5 and 3. Sulfide formation kinetics is favored at a higher pH. For this reason, it is advantageous that the majority of the method is carried out at a relatively high pH, ​​because sulfide formation is a rate-limiting step. In the second or any subsequent additional step, a lower pH is selected to maximize the dissolution of Mn and other impurities. After each such additional step, optionally, solid-liquid separation can be carried out. Most of the conversion to sulfide is usually carried out in the first reaction step, and then completed by the second or any subsequent additional step. Since sulfide will not be formed at a pH lower than 1, the method must be completed at a pH between 1 and 5. Operating at a pH higher than the upper limit will result in insufficient dissolution of Mn.

[0045] After the process is complete, the pH can be further reduced to below 1.5 in order to maximize impurity removal. In fact, although the metal sulfides formed will not redissolve in the absence of an oxidizing agent, some impurities can also be removed from the residue.

[0046] The solid residue obtained in step v. of separating the solid from the solution, which solid residue comprises a major part of the Co and / or Ni as sulphided Co and / or Ni, can be further treated in different ways. Hydrometallurgical treatment of the solid residue is a preferred option.

[0047] Therefore, another embodiment describes a method in which the solid residue is used as a starting material in a subsequent hydrometallurgical refining process. The hydrometallurgical refining process comprises the following steps:

[0048] - leaching the solid residue comprising sulfided Co and / or Ni with a mineral acid, preferably H2SO4, thereby obtaining a solution containing Ni and / or Co;

[0049] - separating the solution from the insoluble solid under conditions that retain the insoluble solid; and,

[0050] - Crystallization of Ni and / or Co from a Ni and / or Co containing solution, preferably as Ni and / or Co sulfate.

[0051] 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 and the sulfiding agent are reacted in step iv. at a temperature between 20°C and 80°C, preferably between 25°C and 80°C. Preferably, the feed and the sulfiding agent are reacted at a substantially constant temperature. Since the reaction is moderately exothermic, only heating is required in the initial stages of the method. In a preferred embodiment, the temperature is controlled at a temperature below 80°C, preferably at a temperature between 40°C and 80°C, more preferably at a temperature of about 60°C. Ensuring that the reaction temperature is not too high can enhance the solubility of H2S in the aqueous medium and thus facilitate the sulfidation reaction kinetics.

[0052] 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 is reacted with the sulfiding agent in step iv. at atmospheric pressure, i.e. at 1 bar, or at a reduced pressure of less than 0.3 bar, preferably less than 0.2 bar and more preferably less than 0.1 bar. Operating under low pressure conditions ensures that the H2S used in the method does not leak into the environment. Preferably, the method is carried out in an atmosphere free of oxygen or air. In a preferred embodiment, the gas atmosphere above the aqueous medium is purged with an inert gas such as N2. Carrying out the method in the absence of an oxidant such as oxygen and air avoids undesirable oxidation of nickel sulfide and / or cobalt.

[0053] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the 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 into the aqueous medium as is, 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 precipitating agent to form metal sulfides, but also advantageously acts as a reducing agent for metals in higher valence states such as 3+ or 4+ oxidation states. The amount of sulfiding agent added is preferably sufficient to saturate the slurry in H2S. Saturation can be easily verified by monitoring the absorption rate of H2S by the reaction mixture. Saturation provides optimal kinetics. Alternatively or in addition, NaHS can be introduced as a sulfiding agent. Ammonium sulfide can also be used.

[0054] Suitable sulfiding agents should preferably be at least partially soluble in the aqueous medium. For example, Li2S reacts with the slurry to form a soluble Li salt and a soluble sulfide. On the other hand, it is believed that sulfides (such as CuS) that are insoluble under the conditions described are not suitable sources of sulfides (respectively sulfiding agents) according to the present invention.

[0055] The inorganic acid is preferably selected from 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 inorganic acid is sulfuric acid. Alternatively, the inorganic acid may be hydrochloric acid.

[0056] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the method is a continuous process. Specifically, the method is carried out under continuous flow conditions.

[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. comprises Ni and / or Co in an amount of 5 wt% to 75 wt%, preferably 10 wt% to 65 wt%, relative to the total weight of the solid metal-containing feed. Preferably, the solid metal-containing feed comprises Ni and / or Co in an amount of 20 wt% to 60 wt%, such as 30 wt% to 50 wt%.

[0058] 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 a battery material that does not contain lithium, such as non-lithiated production waste obtained from battery production or partially recycled battery material from which the lithium content has been removed. In addition to the oxides of Co and / or Ni, a typical battery waste-based feed may also contain anode materials such as carbon, electrode foil and electrolyte. Preferably, at least a major portion (more preferably at least 80% by weight, most preferably at least 90% by weight) of the Co and / or Ni contained in the feed is in the form of their respective metal oxides. The remainder may include Co and / or Ni in metallic form.

[0059] 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. contains Ni in an amount of 10 wt% to 70 wt%, preferably 20 wt% to 60 wt%, more preferably 30 wt% to 55 wt%, relative to the total weight of the solid metal-containing feed. Preferably, the solid metal-containing feed further contains Co in an amount of 0.5 wt% to 15 wt%, preferably 1 wt% to 10 wt%, more preferably 1 wt% to 5 wt%, relative to the total weight of the solid metal-containing feed.

[0060] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the Ni compound and / or the Co compound present in the solid metal-containing feed in step iv. is in the 2+ oxidation state. However, the present method also allows the Ni compound and the Co compound to also contain compounds in a higher oxidation state such as 3+ or 4+. Preferably, the compound is a water-insoluble compound. Advantageously, it has been found that under the reaction conditions of the present invention, Ni and / or Co metal compounds with a higher oxidation state are effectively reduced by a sulfiding agent, preferably H2S, during the first step of the present method.

[0061] In a preferred embodiment, the present invention provides a method according to the first aspect of the present invention, wherein the Ni compound and / or at least one Co compound in the solid metal-containing feed in step iv. comprises carbonates, basic carbonates, sulfates, sulfites, phosphates, hydroxides and / or oxides. Preferably, the Ni compound and / or at least one Co compound in the solid metal-containing feed consists of basic carbonates, hydroxides and / or oxides, most preferably consisting of basic carbonates and / or hydroxides.

[0062] 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. contains Mn in an amount of 1 wt.% to 15 wt.%, preferably in an amount of 3 wt.% to 10 wt.%, relative to the total weight of the solid metal-containing feed.

[0063] In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein the solid metalliferous feed in step iv. comprises Mg in an amount of 0.1 wt.% to 10 wt.%, preferably in an amount of 1 wt.% to 7 wt.%, relative to the total weight of the solid metalliferous feed.

[0064] In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein the solid metal-containing feed in step iv. contains Al in an amount of 0.01 wt.% to 2.00 wt.%, preferably in an amount of 0.02 wt.% to 1.50 wt.%, relative to the total weight of the solid metal-containing feed.

[0065] 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. further comprises Cu in an amount of 0.01 wt.% to 0.20 wt.% relative to the total weight of the solid metal-containing feed and / or Zn in an amount of 0.2 wt.% to 1.0 wt.% relative to the total weight of the solid metal-containing feed.

[0066] 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, the powder preferably having a D50 of less than 100 μm 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 an ASTM standard test method for determining the size of particulate metals and compounds by laser diffraction. Preferably, the D50 of the powder is preferably less than 50 μm, more preferably less than 30 μm, and greater than 0.1 μm, more preferably greater than 1 μm. When present in powder form, metal oxides are more susceptible to reaction. Therefore, an average particle size of less than 100 μm, less than 50 μm or even less than 30 μm is preferred in an industrial setting. It is not required that this powder is a dry powder, it can also be derived from a wet process, such as a filter cake. This is particularly advantageous because it has been found that the formation of sulfided Ni and Co is a rate-controlling step.

[0067] In another embodiment, the method according to the first aspect of the present invention is carried out with continuous operation. In this arrangement, feed and acid are continuously added to the reactor, and slurry is extracted from the reactor simultaneously. Addition and extraction can also be carried out in batches, for example, repeated every 30 minutes. Continuous operation has several advantages. First, continuous operation enhances the use of reactor equipment. Secondly, the quality of solid sulfided Co and / or Ni is more consistent because they are formed in a steady-state scheme. This is conducive to further refining. In an alternative embodiment, the method according to the first aspect of the present invention is carried out with batch operation. In this operation, the first stage of the sulfidation process at a pH between 3.0 and 10.0 is carried out in the first reactor, and the second stage of the process at a pH lower than 3.0 is carried out in the second independent reactor.

Claims

1. A method for producing a metal sulfide containing nickel and / or cobalt, the method comprising the following steps: 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, the mother liquor comprising uncrystallized metal sulfate; iii. separating the crystalline metal sulfate from the mother liquor; iv. reacting at least a portion of the uncrystallized metal sulfate with a sulfiding agent in an acidic aqueous medium to obtain a slurry consisting of a solid phase comprising a precipitate of metal sulfide and an aqueous phase comprising one or more impurities and sulfuric acid; and v. separating the solid phase and the aqueous phase to obtain an aqueous phase and a solid phase comprising metal sulfides, The aqueous medium in step iv. further comprises a solid metal-containing feed containing a nickel compound and / or a cobalt compound.

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

4. The process according to any one of claims 1 to 3, wherein the uncrystallized metal sulfate is reacted with a sulfiding agent in step iv. at a temperature between 40°C and 80°C.

5. The process according to any one of claims 1 to 4, wherein the non-crystallized metal sulfate is reacted with the sulfiding agent in step iv. at atmospheric pressure.

6. The process according to any one of claims 1 to 5, wherein at least a portion of the non-crystallized metal sulfate is reacted with a sulfiding agent in step iv. in an aqueous medium at a pH between 1.5 and 10.

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

8. The process according to any one of claims 1 to 7, 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. The process according to any one of claims 1 to 8, wherein the solid metalliferous feed material in step iv. comprises Ni and / or Co in an amount of 5 to 75 wt.% relative to the total weight of the solid metalliferous feed material.

10. The process according to any one of claims 1 to 9, wherein the solid metalliferous feed in step iv. comprises Ni and / or Co in the form of carbonates, hydroxycarbonates, sulfates, phosphates, hydroxides and / or oxides.

11. The process according to any one of claims 1 to 10, wherein the solid metalliferous feed material in step iv. comprises Mn in an amount of 1 to 15 wt.% relative to the total weight of the solid metalliferous feed material.

12. The process according to any one of claims 1 to 11, wherein the solid metalliferous feed material in step iv. comprises Mg in an amount of 0.1 wt.% to 10 wt.% relative to the total weight of the solid metalliferous feed material.

13. The process according to any one of claims 1 to 12, wherein the solid metalliferous feed material in step iv. comprises Al in an amount of 0.01 wt.% to 2.00 wt.% relative to the total weight of the solid metalliferous feed material.

14. The process according to any one of claims 1 to 13, wherein the solid metalliferous feed in step iv. further comprises Cu in an amount of 0.01 wt.% to 0.20 wt.% relative to the total weight of the solid metalliferous feed and / or Zn in an amount of 0.2 wt.% to 1.0 wt.% relative to the total weight of the solid metalliferous feed.

15. The process according to any one of claims 1 to 14, wherein the solid metalliferous feed material in step iv. is a powder having an average particle size D50 of between 0.1 µm and 100 µm as determined according to ASTM B822-97.

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