Sulfidation of a solid metal feed containing Ni and / or Co

Abstract

The present invention provides a method for treating a metal-containing feed comprising at least one Ni compound and / or at least one Co compound, the feed further comprising one or more impurities, the method comprising: i. reacting the metal-containing feed with a sulfiding agent in an aqueous medium having a pH of 1.5 to 10, thereby obtaining a slurry comprising a Ni- and / or Co-containing solid phase and an aqueous phase comprising one or more water-soluble salts of Mn, Mg, Al, Fe, Ca, B, Na, and / or U; and ii. separating the solid phase and the aqueous phase.

Description

Technical Field

[0001] The present invention relates to a method for treating a metal-containing feedstock that contains at least one Ni compound and / or at least one Co compound, further contains impurities, and does not contain lithium.

Background Art

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

[0003] Due to the decreasing availability of high-purity nickel resources, new processes and refineries for purifying nickel-containing materials are needed. Similarly, the procurement of cobalt is restricted because natural production is limited and it is mainly available in politically unstable regions. Nickel and cobalt refineries need to enable a large-capacity and high-efficiency process to obtain elemental nickel and / or cobalt, or nickel and / or cobalt compounds in the desired amounts and high purity. Among other processes, the sulfidation of Ni and / or Co from laterite ore or battery scrap materials is considered to be one of the more promising routes.

[0004] In this regard, Liu S. et al. have provided an effective method for strongly recovering Ni from laterite ore by H2 reduction using sodium thiosulfate (Na2S2O3) as a promoter. It has been found that when using 20 wt% Na2S2O3 at 1100 °C, a Ni content of 9.97% and a Ni recovery rate of 99.24% are achieved. 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] Chinese Patent No. 113802002 discloses a method for recycling valuable metals in a lithium battery by a wet process. According to this method, waste lithium battery powder is selectively leached under the condition of introducing hydrogen sulfide gas under pressure, so that Mn, Li and Al metal ions enter the first-stage leachate, and nickel, cobalt, copper and iron exist in the form of sulfides in the first-stage leach residue, and only a small amount of sulfuric acid is consumed during the process. Then, the pH value of the first-stage leachate is adjusted to remove aluminum and manganese. Following the first-stage leaching process, this method requires a sophisticated purification procedure to obtain high-purity Ni.

[0006] Furthermore, in the use of energy and materials, there is a need for a new method to obtain high-purity and high-efficiency nickel and / or cobalt.

Summary of the Invention

[0007] The present invention provides a solution to at least one of the above-mentioned problems by providing a method for treating a lithium-free metal-containing feed as recited in claim 1. The inventors had assumed that compounds such as nickel hydroxide and cobalt hydroxide would form water-soluble nickel sulfate and water-soluble cobalt sulfate respectively when contacted with sulfuric acid in the absence of a sulphidising agent. The formation of such water-soluble compounds hinders direct recovery and as a result reduces the recovery of Ni and Co from the process. Thus, sulphidation is preferably first carried out at a relatively high pH, such as between 3 and 10, in order to enable complete conversion, more specifically complete sulphidation, of the Ni and / or Co compounds in the lithium-free metal-containing feed, after which an acid is added to further dissolve all impurities together with the formation of water-soluble sulphates and at the same time reduce the pH of the aqueous reaction medium to a pH of less than 3.5 or even less than 3.0.

DETAILED DESCRIPTION OF THE INVENTION

[0008] Unless otherwise defined, all terms used in the disclosure of the present invention, including technical and scientific terms, have the meaning commonly understood by one of ordinary skill in the technical field to which this invention belongs. Definitions of terms are included for further guidance 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 than one compartment.

[0009] As used herein, "about", when referring to a measurable value such as a parameter, quantity, duration, etc., means a variation of ±20% or less, preferably ±10% or less, more preferably ±5% or less, even more preferably ±1% or less, still more preferably ±0.1% or less from the specified value, as long as such variation is appropriate for the practice of the disclosed invention. It should be understood, however, that the value itself to which the modifier "about" refers is also 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, specifying the presence of what follows, e.g., components, and do not exclude or preclude the presence of additional, unrecited components, features, elements, members, steps known in the art or disclosed herein.

[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 are understood as weight percentages abbreviated as "wt%", or volume percentages abbreviated as "vol%", unless otherwise defined or unless it is clear from the use and context in which they are used that they have a different meaning to a person skilled in the art. Unless otherwise specified, the weight percentage of an element or compound is calculated relative to the dry weight of the compound or composition containing the element or compound.

[0012] 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 in nickel metallurgy obtained mainly from the treatment of laterite ores containing nickel and small amounts of cobalt. MHP is a solid product typically prepared by extracting nickel and cobalt from laterite ores.

[0013] In the context of the present invention, the term "CHIP" is considered an abbreviation of the term "cobalt hydroxide intermediate precipitate". The cobalt hydroxide intermediate mainly consists of cobalt and typically has a cobalt content of 25 wt% to 40 wt% based on the total weight of the intermediate product. Typically, the CHIP contains a significant amount of nickel. The CHIP is known to have very few impurities and is therefore optimal for the method of the present invention.

[0014] In the context of the present invention, the term "lithium-free metal-containing feed" is synonymous with the term "metal-containing feed" and refers to a solid feed comprising an MHP product, a CHIP product, or a mixture of two or more MHP products, two or more CHIP 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 a Co(II) compound, respectively. Further, the Ni compound and the Co compound may be included in a higher oxidation state such as 3+ or 4+, or the metal-containing feed may include a mixture of a Ni compound and / or a Co compound in oxidation state 2+ and a Ni compound and / or a Co compound in oxidation states 3+ and / or 4+.

[0015] In the context of the present invention, the term "lithium-free metal-containing feed" refers to a solid feed containing less than 3% by weight of lithium, preferably less than 2% by weight of lithium, preferably less than 1% by weight of lithium, more preferably less than 0.5% by weight of lithium, based on the total weight of the feed. Most preferably, the feed is lithium-free.

[0016] In the context of the present invention, the term "continuous process" is considered to be a process in which the resulting solution has a substantially constant composition. Specifically, a continuous process is a process in which the resulting solution has a constant composition within the range considered to be normal process variations. More specifically, the resulting solution 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 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 aqueous solutions. The aqueous medium facilitates the handling of the contents of the reactor, such as mixing or pumping. The aqueous medium may already contain other components involved in the reaction or may be added later. The aqueous medium may particularly contain mineral acids.

[0018] Preferably, a mineral acid such as sulfuric acid or hydrochloric acid is supplied intermittently or gradually to the process according to the present invention. The lithium-free metal-containing feed can be supplied intermittently or gradually to the process. Further, the lithium-free metal-containing feed is preferably supplied only at the initial stage of the process. The mineral acid may be added as it is, or may be generated in situ, for example, by adding NiSO4 or NiCl2 to an aqueous reaction medium in which H2S is introduced as a sulfiding agent. When NiSO4 or NiCl2 is brought into contact with H2S, a metal sulfide such as NiS and / or CoS precipitates, and a mineral acid, sulfuric acid or hydrochloric acid is generated in situ, respectively. Advantageously, according to such an embodiment, the total amount of Co and / or Ni in the aqueous medium increases, thereby improving the recovery efficiency. This process has sufficient robustness to handle Co- and / or Ni-containing solutions from impure waste liquid streams.

[0019] The sulfiding agent used in the contacting step must clearly be one that readily reacts with Co and / or Ni compounds. Therefore, a suitable sulfiding agent preferably dissolves at least partially in the aqueous medium. Preferably, a sulfiding agent such as H2S 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 sulfiding agent to the process is controlled within a range of ±20% or less, preferably ±10% or less, more preferably ±5% or less, still more preferably ±3% or less of its supply rate.

[0020] In a first aspect, the present invention is a method for treating a lithium-free metal-containing feed comprising at least one Ni compound and / or at least one Co compound, the feed further comprising one or more impurities including Mn, Mg, Al, Fe, Ca, B, Na and / or U, the method comprising i. contacting the lithium-free metal-containing feed with a sulfiding agent in an aqueous medium at pH 1.5 to 10, thereby obtaining a slurry comprising a Ni- and / or Co-containing solid phase and an aqueous phase comprising one or more water-soluble salts of Mn, Mg, Al, Fe, Ca, B, Na and / or U, and ii. separating the solid phase and the aqueous phase, thereby obtaining a solid phase containing Ni(II) sulfide and / or Co(II) sulfide and an aqueous phase containing one or more water-soluble components such as salts of Mn, Mg, Al, Fe, Ca, B, Na and / or U.

[0021] Preferably, step i comprises a. contacting the metal-containing feed with a sulfurizing agent in an aqueous medium having a pH of 3 to 10 in the presence of a mineral acid, thereby obtaining a slurry; b. adding a mineral acid to the slurry obtained in step a to obtain a slurry having a pH of less than 3; and c. adding a sulfurizing agent to the slurry obtained in step b, thereby obtaining a slurry containing a Ni- and / or Co-containing solid phase and an aqueous phase containing one or more water-soluble salts of Mn, Mg, Al, Fe, Ca, B, Na and / or U.

[0022] Preferably, the lithium-free metal-containing feed containing at least one Ni compound and / or at least one Co compound is provided as a solid or as a slurry, i.e., as a solid in an aqueous medium. The pH of the aqueous medium in step i is preferably controlled by adding a mineral acid such as sulfuric acid or hydrochloric acid. A basic pH in the range of 7 to 10 can be the result of the basicity of the lithium-free metal-containing feed. Specifically, the present invention provides a method in which the lithium-free metal-containing feed in the aqueous medium first reacts with the sulfurizing agent at a pH of 3.0 to 10, preferably 3 to 7, more preferably 3 to 6, and then the pH of the aqueous medium is lowered to a pH of less than 3.0. More preferably, the pH of the aqueous medium is lowered to a pH from 1.5 to 3.0. It is likewise possible to lower the pH to a pH value of less than 1.5. Thus, step i is essentially carried out in at least two stages, with each stage of step i being carried out at a different pH. Preferably, the sulfurization reaction in step i 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.

[0023] The inventors considered that when compounds such as nickel hydroxide and cobalt hydroxide come into contact with sulfuric acid in the absence of a sulfurizing agent, they form water-soluble nickel sulfate and / or water-soluble cobalt sulfate, respectively. When such water-soluble compounds are formed, the recovery rates of Ni and Co decrease. Therefore, preferably, sulfidation is first carried out at a higher pH, such as a pH between 3 and 10, more specifically to enable complete conversion, more specifically complete sulfidation, of the Ni and / or Co compounds in the lithium-free metal-containing feed, and then a mineral acid such as sulfuric acid is further added to dissolve all impurities accompanied by the formation of water-soluble sulfates, and at the same time reduce the pH of the aqueous reaction medium to a pH less than 3.0 or even less than 2.5. Preferably, the sulfidation is carried out in the first stage at a pH of 3 to 6, preferably 3 to 5, more preferably 3 to 4. Preferably, the sulfidation is carried out in the second stage after reducing the pH of the aqueous solution to a pH of 1.5 to 3.0, preferably 2 to 3, more preferably about 2.2, 2.4, 2.6, 2.8 or any value in between. Preferably, the difference in pH between the first stage and the second stage is at least 0.2 pH units, preferably at least 0.5 pH units, more preferably at least 1 pH unit, or even at least 1.5 pH units.

[0024] Therefore, it is expected to provide a process that enables the selective leaching of impurities such as Mg and Mn from a feed material containing Ni and / or Co. Other impurities typically contained in such a lithium-free metal-containing feed include, but are not limited to, Al, Fe, Ca, B, Na, and U. The impurities are typically contained in an amount of less than 10% by weight, preferably less than 5% by weight, and even more preferably less than 2% by weight, based on the total weight of the metal-containing feed. Other impurities such as Zn and Cu, although not limited, tend to remain in the solid phase because they do not form water-soluble salts in the process environment. Such impurities can be separated from the Ni and / or the Co in the state-of-the-art refining process. Further, the organic carbon present in the metal feed may be washed away as a water-soluble compound and recovered in the aqueous phase.

[0025] Generally, the refining process flow sheet for the refining of MHP and / or CHIP of Ni and / or Co depends on the extraction of impurities such as Mn and Mg from the solution. This method provides an alternative way to remove Mg and Mn from Ni. Through the following series of reactions, when Ni and Co are present, they are recovered in the solid phase, and the selected impurities (e.g., Mn and Mg) in the lithium-free metal-containing feed are recovered in the aqueous phase:

Chemical formula

[0026] Also, other elements 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 materials such as F, W, Si, P, C, K, Fe, Cl, SO4, etc. will be recovered in the aqueous phase. Other impurities such as Cu, Zn, Pb, and Cd are reported in the solid residue. The formation of a solid residue containing Co sulfide and / or Ni sulfide depleted in Mn has several advantages for the hydrometallurgical refining process. Since Mn does not dilute the Ni and / or Co-containing solution and there is no need to isolate Mn by solvent extraction or the like, a more efficient process becomes possible.

[0027] 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) sulfide and / or Co(II) sulfide obtained in step ii is leached with an acid and / or an oxidizing agent such as Cl2. In this way, a high-purity Ni salt and / or Co salt solution can be obtained, while the sulfurizing agent can be regenerated and recycled to step i of the method of the present invention. When NiS and CoS are leached with an acid, Ni salts and / or Co salts are formed respectively, and H2S is formed. For example, the reaction of NiS with sulfuric acid forms NiSO4 and H2S, which can advantageously be recycled and reused as a sulfurizing agent in step i. Similarly, the reaction of NiS with chlorine gas forms NiCl2 and S. S is advantageously reduced to become a sulfurizing agent such as H2S and can be recycled and reused as a sulfurizing agent in step i.

[0028] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, in which the lithium-free metal-containing feed in the aqueous medium first reacts with the sulfurizing agent at a pH of 3 to 8, preferably 3 to 6. It has been found that the higher the pH, the more the sulfidation is promoted, and the lower the pH, the more the leaching of impurities from the metal-containing feed is promoted. However, the 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 to 4, optimal process conditions are obtained. Preferably, the first sulfidation step is carried out with a treatment time of 1 to 16 hours, preferably 2 to 12 hours, more preferably 2 to 8 hours.

[0029] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, in which the lithium-free metal-containing feed is reacted at a pH of 3 to 10 and then the pH of the aqueous medium is lowered to a pH higher than 1.5 and lower than 3.0. It has been found that lowering the pH promotes the formation of sulfates of impurity metals in the feed. Also, it has been found that lowering the pH below 1.5 does not significantly improve the dissolution of impurities and the cost of the mineral acid consumed in the process cannot be sufficiently recovered. The inventors have found that when the second sulfidation reaction is carried out at a pH of about 2.0 to 2.5, optimal process conditions are obtained. Preferably, the second sulfidation step is carried out with a treatment time of 2 to 16 hours, preferably 2 to 12 hours, more preferably 2 to 8 hours.

[0030] The multi-step process is advantageous when most of the process is carried out at a pH of 3.0 to 10.0, or 3.0 to 6.0, and the pH is lowered to a pH higher than 1.5 and lower than 3.0 in the second or subsequent addition steps. The rate of formation of sulfide is promoted the higher the pH. For this reason, since the formation of sulfide is the rate-determining step, it is advantageous to carry out most of the process at a relatively high pH. In the second or subsequent addition steps, a lower pH is selected to maximize the dissolution of Mn and other impurities. After each such addition step, solid-liquid separation can be optionally carried out. Most of the conversion to sulfide is usually carried out in the first reaction step and then completed in the second or subsequent addition steps. Since sulfide formation does not occur at a pH below 1, the process needs to be completed at a pH between 1 and 5. Working at a pH above the upper limit results in insufficient dissolution of Mn.

[0031] After completion of the process, the pH can also be further lowered to less than 1.5 to maximize the removal of impurities. In fact, the formed metal sulfides do not redissolve in the absence of an oxidizing agent, but some impurities can be removed from the residue.

[0032] The solid residue obtained in the step of separating the solid from the solution and containing most of Co and / or Ni as Co sulfide and / or Ni sulfide can be further processed in different ways. Hydrometallurgical treatment of the solid residue is a preferred option.

[0033] Therefore, in a further embodiment, a process is described in which the solid residue is used as a starting material in a subsequent hydrometallurgical purification process. The hydrometallurgical refining process comprises - leaching the solid residue containing Co sulfide and / or Ni sulfide with a mineral acid, preferably H2SO4 or HCl, optionally in the presence of oxygen and in the presence of an oxidizing agent such as HCl, thereby obtaining a Ni and / or Co-containing solution; - separating the solution from the solid under the condition that insoluble solids remain; and - Crystallizing Ni and / or Co from the Ni- and / or Co-containing solution, preferably as nickel sulfate and / or cobalt sulfate.

[0034] In a preferred embodiment, the mother liquor from the crystallization unit containing NiSO4 and / or CoSO4 is recycled to the aqueous reaction medium to form sulfuric acid in situ in the presence of a sulfurizing agent.

[0035] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the volume ratio φ of the mineral acid used in step ia to the total amount of the mineral acid used in step i AC is from 0.01 to 0.95. Preferably, the ratio φ AC is from 0.05 to 0.90, more preferably from 0.40 to 0.90. Most preferably, the ratio φ AC is about 0.40, 0.50, 0.60, 0.70, 0.80 or 0.90, or any value therebetween.

[0036] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feed reacts with the sulfurizing agent at a temperature of 20 °C to 80 °C, preferably 30 °C to 80 °C. Preferably, the feed reacts with the sulfurizing agent at a substantially constant temperature. Since the reaction is moderately exothermic, heating alone may be required at the initial stage of the process. In a preferred embodiment, the temperature is controlled to a temperature below 80 °C, preferably a temperature of 40 °C to 80 °C, more preferably about 60 °C. By preventing the reaction temperature from being too high, the solubility of H2S in the aqueous medium can be increased, and as a result, the rate of the sulfidation reaction is accelerated.

[0037] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feed reacts with the sulfurizing agent at normal 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. By operating under low pressure conditions, it is ensured that H2S used in the process does not leak into the environment. Preferably, the process proceeds in an atmosphere free of oxygen or air. By performing the process including the filtration step without an oxidizing agent such as oxygen and air, unnecessary oxidation of nickel sulfide and / or cobalt sulfide can be avoided.

[0038] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the weight ratio of the lithium-free metal-containing feed to the amount of the aqueous medium is at least 0.05, preferably at least 0.10, more preferably at least 0.15, even more preferably at least 0.20 or further 0.25, and most preferably at least 0.30. Preferably, the weight ratio is at most 0.50, preferably at most 0.45, more preferably at most 0.40. It has been found that as the weight ratio increases, the efficiency of the process improves in terms of energy consumption. However, it has been found that as the weight ratio increases, the separation efficiency of impurities such as Ca impurities decreases.

[0039] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the sulfurizing agent is one or more selected from the group consisting of H2S, NaHS, NH4HS, Na2S, (NH4)2S and Li2S, preferably one or more selected from the group consisting of H2S, NaHS and Li2S. H2S and NaHS are preferred sources of sulfide. Most preferably, the sulfurizing agent contains H2S. H2S can be introduced directly into the aqueous medium or generated in situ by adding elemental sulfur under reducing conditions, more specifically in the presence of H2. In the present invention, the sulfurizing agent not only acts as a precipitant to form metal sulfides, but also advantageously acts as a reducing agent for high-valent metals in an oxidation state such as 3+ or 4+. The amount of the sulfurizing agent added is preferably an amount sufficient to saturate the slurry with H2S. Saturation can be easily confirmed by monitoring the absorption rate of H2S by the reaction mixture. The optimal rate is obtained by saturation. Alternatively or additionally, NaHS can be introduced as a sulfurizing agent. It is assumed that NaHS forms H2S in an acidic aqueous medium, which dissolves and reacts with the slurry, and NaOH reacts with the acid to form a salt. Since only a limited amount of this salt is produced, it is not very desirable. Similarly, Na2S can be used as a sulfurizing agent. However, it is not very desirable because it generates twice the amount of salt as NaHS. Ammonium sulfide can also be used.

[0040] Preferably, the suitable sulfurizing agent is at least partially soluble in the aqueous medium. For example, Li2S reacts with the slurry to form soluble Li salts and soluble sulfides. On the other hand, insoluble sulfides such as CuS under the described conditions are not regarded as suitable sources of sulfides according to the present invention, i.e., sulfurizing agents.

[0041] The mineral acid is preferably selected from the list consisting of H2SO4, HCl, H3PO4, and HNO3, or mixtures thereof. In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the mineral acid is sulfuric acid. Alternatively, the mineral acid can be hydrochloric acid.

[0042] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feedstock contains Ni and / or Co in an amount of 5 to 75% by weight, preferably 10 to 65% by weight, based on the total weight of the lithium-free metal-containing feedstock. Preferably, the lithium-free metal-containing feedstock contains Ni and / or Co in an amount of 20 to 60% by weight, more preferably 30 to 50% by weight.

[0043] In an alternative embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feedstock comprises a lithium-free battery material such as a delithiated manufacturing waste material obtained from battery manufacturing, or a partially recycled battery material from which the lithium content has been removed.

[0044] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feedstock contains Ni in an amount of 10 to 70% by weight, preferably 20 to 60% by weight, more preferably 30 to 55% by weight, based on the total weight of the lithium-free metal-containing feedstock. Preferably, the lithium-free metal-containing feedstock further contains Co in an amount of 0.5 to 15% by weight, preferably 1 to 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the lithium-free metal-containing feedstock.

[0045] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the Ni compound and / or the Co compound present in the lithium-free metal-containing feedstock is in the oxidation state 2+. Further, the method of the present invention also allows the Ni compound and the Co compound to contain compounds in a higher oxidation state such as 3+ or 4+. Preferably, the compound is a water-insoluble compound. Advantageously, under the reaction conditions of the present invention, it has been found that Ni and / or Co metal compounds having a higher oxidation state are efficiently reduced by a sulfurizing agent, preferably H2S, during the first step of the method of the present invention.

[0046] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the Ni compound and / or at least one Co compound in the lithium-free metal-containing feedstock comprises a carbonate, a hydroxycarbonate, a sulfate, a sulfite, a phosphate, a hydroxide, and / or an oxide. Preferably, the Ni compound and / or at least one Co compound in the lithium-free metal-containing feedstock is composed of a hydroxycarbonate, a hydroxide and / or an oxide, most preferably a hydroxycarbonate and / or a hydroxide.

[0047] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feedstock contains Mn in an amount of 1 to 15% by weight, more specifically 3 to 10% by weight, based on the total weight of the lithium-free metal-containing feedstock.

[0048] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feedstock contains Mg in an amount of 0.1 to 10% by weight, more specifically 1 to 7% by weight, based on the total weight of the lithium-free metal-containing feedstock.

[0049] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feedstock contains Al in an amount of 0.01 to 2.00% by weight, more specifically 0.02 to 1.50% by weight, based on the total weight of the lithium-free metal-containing feedstock.

[0050] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feedstock further contains Cu in an amount of 0.01 to 0.20% by weight based on the total weight of the lithium-free metal-containing feedstock, and / or Zn in an amount of 0.2 to 1.0% by weight based on the total weight of the lithium-free metal-containing feedstock.

[0051] In a preferred embodiment, the present invention provides a method according to a first aspect of the present invention, wherein the lithium-free metal-containing feed is a powder, and the powder preferably has 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 an ASTM standard test method for measuring the particle size of granular 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 compounds are more reactive and easier to react when present in powder form. 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. Such powders do not have to be dry powders and can be derived from wet processes such as filter cakes. This is particularly advantageous since the formation of Ni sulfide and Co sulfide has been found to be the rate-limiting step.

[0052] 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 setting, the feed and the acid are continuously added to the reactor while the slurry is being withdrawn from the reactor. The addition and withdrawal can also be carried out batchwise, for example, repeated every 30 minutes. Continuous operation has several advantages. First, the use of reactor equipment is enhanced by continuous operation. Second, the quality is more stable since solid Co sulfide and / or Ni sulfide are formed in a steady state. This facilitates further refining. In an alternative embodiment, the method according to the first aspect of the present invention is carried out in a batch operation. In such an operation, the first stage of the sulfidation process is carried out in a first reactor at a pH between 3.0 and 6.0, and the second stage of the process is carried out in a second separate reactor at a pH of less than 3.0.

Examples

[0053] The following examples are intended to clarify the present invention further and are not intended to limit the scope of the present invention.

[0054] Example 1 220 kg of impure Ni hydroxide powder is added to a reactor. 800 L of water is added and the mixture is stirred. The lithium-free metal-containing feed product contains 32 wt% Ni, 5.5 wt% Mn, 1.6 wt% Co, 0.8 wt% Al, and 2.4 wt% Mg.

[0055] H2S is injected into the slurry at a constant rate of 20 kg / h. The temperature is adjusted to 40 °C. H2SO4 solution (1000 g / L) is added at a constant rate of 3.8 kg / h to bring the pH to 3.7 in the first stage and to about 2.8 in the second stage. The temperature is maintained at 40 °C and H2S is continuously injected at the specified rate. The addition of H2SO4 is stopped when the pH of the slurry reaches 2.5. This is the situation after 13 hours.

[0056] The slurry is filtered to obtain 110 kg of solid residue and 700 L of solution after washing and drying. The material balance for the whole experiment can be found in Table 1 below. [Table 1]

[0057] Example 2 200 kg of impure Ni hydroxide powder is added to a reactor. 630 L of water is added and the mixture is stirred. The lithium-free metal-containing feed product contains 32 wt% Ni, 5.5 wt% Mn, 1.6 wt% Co, 0.8 wt% Al, and 2.4 wt% Mg.

[0058] Inject H2S into the slurry at a constant rate of 20 kg / h. Adjust the temperature to 60 °C. Add 38 kg of H2SO4 over 6 hours to bring the pH of the slurry at the end of Step 1 to 6.3. In Step 2, add 9 kg of acid (1000 g / L H2SO4) to the slurry over 6 hours to bring the pH to 1.96. The H2S injection rate is maintained at 20 kg / h in Step 2. The temperature is maintained at 60 °C.

[0059] Filter the slurry to obtain 122 kg of solid residue and 550 L of solution after washing and drying. The material balance for the entire experiment can be found in Table 2 below.

Table 2

[0060] Example 3 Add 300 kg of Li-depleted battery scrap to the reactor. Add 1300 L of water and stir the mixture. The metal-containing feed product contains 33 wt% Ni, 8 wt% Mn, 7.4 wt% Co, 1.9 wt% Li, 0.5 wt% Al, 0.3 wt% Cu, 0.9 wt% F, 0.1 wt% Fe and 33 wt% C.

[0061] Inject H2S into the slurry at a constant rate of 40 kg / h. Adjust the temperature to 40 °C. Add 88 kg of H2SO4 over 2 hours to bring the pH of the slurry at the end of Step 1 to 4.3. In Step 2, add 35 kg of acid (1000 g / L H2SO4) to the slurry over 3.5 hours to bring the pH to 2.4. The H2S injection rate is maintained at 20 kg / h in Step 2. The temperature is maintained at 40 °C.

[0062] Filter the slurry to obtain 272 kg of solid residue and 1200 L of solution after washing and drying. The material balance for the entire experiment can be found in Table 3.

Table 3

[0063] Example 4 A continuous two-step sulfidation process is carried out using two reactors connected in series (referred to as Reactor A and Reactor B). The lithium-free metal-containing feed product contains 32 wt% Ni, 5.5 wt% Mn, 1.6 wt% Co, 0.8 wt% Al and 2.4 wt% Mg.

[0064] 200 kg / h of the feed product and 760 L / h of water are continuously added to Reactor A and the mixture is stirred. After the reaction, to maintain a level of 4 m in Reactor A, the slurry is pumped from Reactor A to Reactor B. 3 To maintain a level of 4 m, the slurry is continuously removed from Reactor B onto a filter. H2S is continuously injected into Reactors A and B at mass flow rates of 80 kg / h and 40 kg / h respectively. After 7 days of operation, the pH in Reactor A rises to 4.6. To control the pH to 2, HCl is added to Reactor B to a mass flow rate of 82 kg / h of an HCl solution (430 g / L). 3 After 7 days, the slurry is filtered to obtain 102 kg of solid residue per hour and 750 L of solution after washing and drying. The material balance for the entire experiment can be found in Table 4.

[0065]

Table 4

[0066] Example 5 122 kg of the sulfide residue produced in Example 2 is added to an autoclave together with 150 L of sulfuric acid (1000 g / L H2SO4) and 1050 L of water. The sulfide residue contains 52 wt% Ni, 2.6 wt% Co and 35 wt% S, and further contains 13.4 wt% impurities. The slurry is heated to 60 °C and an oxygen pressure of 5 bara is applied to the reactor. For 6 hours, the temperature is maintained at 60 °C and oxygen is added to maintain 5 bara.

[0067] ​After 6 hours, the slurry is filtered to obtain 36 kg of solid residue and 1120 L of solution after washing and drying. The material balance for the entire experiment can be found in Table 5. It is found that approximately 80% of the S present in the sulfide residue is oxidized to elemental S.

Table 5

Claims

1. A method for treating a solid metal-containing feedstock, wherein the solid metal-containing feedstock contains at least one Ni compound and / or at least one Co compound, and an amount of Li less than 3% by weight based on the total weight of the feedstock, and the feedstock further contains one or more impurities including Mn, Mg, Al, Fe, Ca, B, Na and / or U, and the method comprises: i. a. contacting the solid metal-containing feedstock with a sulfurizing agent in an aqueous medium having a pH of 3 to 10 in the presence of a mineral acid, thereby obtaining a slurry; b. adding a mineral acid to the slurry obtained in step a to obtain a slurry having a pH of less than 3; c. adding a sulfurizing agent to the slurry obtained in step b, thereby obtaining a slurry containing a Ni and / or Co-containing solid phase and an aqueous phase containing one or more water-soluble salts of Mn, Mg, Al, Fe, Ca, B, Na and / or U; ii. separating the solid phase and the aqueous phase, thereby obtaining a solid phase containing Ni(II) sulfide and / or Co(II) sulfide and an aqueous phase containing one or more water-soluble salts of Mn, Mg, Al, Fe, Ca, B, Na and / or U.

2. The method according to claim 1, wherein step ia consists of contacting the solid metal-containing feedstock with a sulfurizing agent in an aqueous medium before introducing the mineral acid.

3. The method according to claim 1 or 2, wherein the solid phase obtained in step ii is leached with an acid and / or an oxidizing agent to regenerate the sulfurizing agent, and the regenerated sulfurizing agent is used in step i.

4. The method according to any one of claims 1 to 3, wherein the solid metal-containing feedstock reacts at a pH of 3.0 to 6.0 before the pH of the aqueous medium is reduced to a pH of 2.0 to 2.

5.

5. The volume ratio φ of the total amount of the mineral acid used in step ia to the mineral acid used in step i ＡＣ is 0.40 to 0.

90.

6. The method according to any one of claims 1 to 5, wherein the solid metal-containing feed in the aqueous medium reacts with the sulfurizing agent at a pH of 3.0 to 4.0 in step ia.

7. The method according to any one of claims 1 to 6, wherein the solid metal-containing feed reacts with the sulfurizing agent at a temperature of 25 °C to 80 °C.

8. The method according to any one of claims 1 to 7, wherein the solid metal-containing feed reacts with the sulfurizing agent at atmospheric pressure.

9. The sulfurizing agent is H ２ S, NaHS, NH ４ HS, Na ２ S, (NH ４ ) ２ S and Li ２ S, and is one or more selected from the group consisting of, the method according to any one of claims 1 to 8.

10. The method according to any one of claims 1 to 9, wherein the mineral acid is sulfuric acid.

11. The method according to any one of claims 1 to 10, wherein the solid metal-containing feed contains Ni and / or Co in an amount of 5 to 75% by weight based on the total weight of the solid metal-containing feed.

12. The method according to any one of claims 1 to 11, wherein the Ni compound and / or at least one of the Co compounds in the solid metal-containing feed contains carbonate, hydroxycarbonate, sulfate, phosphate, hydroxide, and / or oxide.

13. The method according to any one of claims 1 to 12, wherein the solid metal-containing feed contains Mn in an amount of 1 to 15% by weight based on the total weight of the solid metal-containing feed.

14. The method according to any one of claims 1 to 13, wherein the solid metal-containing feed contains Mg in an amount of 0.1 to 10% by weight based on the total weight of the solid metal-containing feed.

15. The method according to any one of claims 1 to 14, wherein the solid metal-containing feedstock contains Al in an amount of 0.01 to 2.00% by weight based on the total weight of the solid metal-containing feedstock. **Claim 16** The method according to any one of claims 1 to 15, wherein the solid metal-containing feedstock further contains Cu in an amount of 0.01 to 0.20% by weight based on the total weight of the solid metal-containing feedstock, and / or Zn in an amount of 0.2 to 1.0% by weight based on the total weight of the solid metal-containing feedstock. **Claim 17** The method according to any one of claims 1 to 16, wherein the solid metal-containing feedstock 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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