Method for producing metal-containing aqueous solutions

Abstract

The present disclosure relates to a method of producing an aqueous metal-containing solution, the method comprising acid leaching a lithium-containing feedstock and acid leaching a metal-based raw material. The lithium-containing feedstock may originate from a lithium-ion battery and may include one or more of the positive electrode active materials nickel, cobalt, or manganese.

Description

[Technical field]

[0001] The present disclosure relates to a method for producing an aqueous metal-containing solution, the method comprising acid leaching a lithium-containing raw material and acid leaching a raw metal-based material, in particular the lithium-containing raw material originating from a lithium-ion battery and including one or more of the positive electrode active materials nickel, cobalt, or manganese. [Background technology]

[0002] Especially considering the increasing demand for batteries, for example for electric vehicles, on the one hand, and the scarcity of resources on the other hand, some of the metals contained in batteries, such as lithium, cobalt, nickel, aluminum, copper or manganese, are valuable, so that the recovery of metals, for example from waste batteries, is crucial to realize an economical and environmentally friendly production of batteries. Batteries can be based on different technologies, such as for example nickel-cadmium (NiCd) or nickel-metal hydride (NiMH) technology. In the transport sector, lithium-ion secondary batteries (LIBs) have become the most widespread power source. In LIBs, lithium composite oxides, which contain lithium and the transition metals nickel, cobalt and / or manganese (the so-called "NCM metals"), are usually used as the active material of the positive electrode and are the main metals targeted for recovery.

[0003] From the standpoint of energy consumption and cost efficiency, hydrometallurgical methods are often preferred over pyrometallurgical methods for material recovery. Such hydrometallurgical methods utilize multi-step processes and chemical processing to extract metals from raw materials, and provide the metals separately or in advance as aqueous solutions of their salts, e.g., sulfates, in the desired stoichiometry for the synthesis of precursor materials in battery manufacturing. The composition of the aqueous metal salt solutions can be adjusted to the desired stoichiometry by the addition of single or mixed metal components.

[0004] For example, in view of the increasing demand for metals used in battery manufacturing, particularly in lithium-ion batteries, and increasing sensitivity to environmental issues, there is a significant need to improve hydrometallurgical processes to ensure efficient leaching of metals of interest from raw materials with high leaching yields, while at the same time reducing chemical consumption and waste generation. Summary of the Invention

[0005] It is an object of the present disclosure to provide a method for efficient leaching of lithium-bearing raw materials, such as black mass, to produce an aqueous metal-bearing solution, which is cost-effective and allows for increased leaching yields while at the same time reducing the consumption of chemicals and the amount of waste produced.

[0006] It is a further object of the present disclosure to provide a method for leaching lithium-containing feedstock that allows for the production of metal-containing aqueous solutions that are enriched in the metal of interest and that can be used to produce battery grade metal salts, such as metal sulfates, for battery precursor synthesis.

[0007] It is further an object of the present disclosure to provide an efficient method for leaching feedstocks including materials derived from recycled lithium-ion batteries or lithium-ion battery manufacturing scrap (so-called "black mass") that is cost-effective and allows for increased leaching yields of the target metals, in particular the cathode active metals Ni, Co and / or Mn, while at the same time reducing the consumption of chemicals and the amount of waste generated.

[0008] It is further an object of the present disclosure to provide an efficient method for leaching feedstocks including materials derived from recycled lithium-ion batteries or lithium-ion battery manufacturing scrap (so-called "black mass"), which makes it possible to control the ratio of the metals of interest, in particular the positive electrode active metals Ni, Co and / or Mn, in the resulting aqueous metal-containing solution, and to result in an aqueous metal-containing solution enriched in the metals of interest.

[0009] A further object of the present disclosure is to provide an efficient method for leaching lithium-containing raw materials, which allows for the integration of battery recycling and battery precursor synthesis.

[0010] One or more of the objects outlined above can be achieved by a method for producing an aqueous metal-containing solution as claimed in independent claim 1. The independent claim 1 and the dependent claims may be combined in any technically suitable and judicious manner to provide further aspects of the invention.

[0011] Specifically, disclosed herein is a method of producing an aqueous metal-containing solution, the method comprising: performing a first acid leach of a lithium-containing feedstock using a first leach solution to form the aqueous metal-containing solution, to obtain a first leachate; and performing a second acid leach of a raw metal-based material using a second leach solution to obtain a second leachate.

[0012] It has been surprisingly found that the process disclosed herein, which comprises a two-stage process of first and second leaching operations using different feedstocks, has the advantage that the synergistic effect of processing a lithium-containing feedstock such as black mass and a metal-based feedstock such as MHP together can increase the leaching yield, particularly of desirable cathode active metals such as Ni, Co or Mn, while reducing the amount of chemical consumption and waste generated, making the overall leaching process more efficient and economically viable. Thus, the process according to the present disclosure has the advantage that the recycling of used or discarded batteries can be integrated into the synthesis of battery precursors, making battery production more efficient.

[0013] Various aspects will now be described with reference to the drawings. Obviously, the drawings in the following description merely illustrate some aspects of the present application, and those skilled in the art can further derive other drawings from these drawings without creative efforts. [Brief description of the drawings]

[0014] [Figure 1]Figure 1 is a schematic flow chart showing one embodiment of a method for producing a metal-containing aqueous solution according to the present disclosure, applying a parallel configuration and using black mass (BM) as a lithium-containing raw material and mixed nickel hydroxide precipitate (Ni-MHP) as a metal-based raw material raw material. With reference to Figure 1, black mass obtained from, for example, crushed lithium-ion batteries containing Li and Ni, Co and / or Mn as target metals and metallic impurities such as Fe, Al, Cu, Zn, Mg, K and Ca is leached (A) by reductive acid leaching using a leaching solution of concentrated sulfuric acid (H2SO4), hydrogen peroxide (H2O2, 50 wt%) and water in a continuous process using, for example, a continuous stirred tank reactor (CSTR). By BM leaching (A), all target metals (Li and Ni, Co and / or Mn) and impurities contained in the BM are dissolved in the leachate (BM leachate) in the form of their sulfates, leaving mainly graphite as the undissolved fraction. The undissolved fraction is separated from the BM leachate by filtration (C1) and washed with water if necessary to remove any residual leach solution. The Ni-MHP, which may contain Ni and Co and / or Mn as metals of interest and metallic impurities such as Zn, Mg and Ca, is leached by reductive acid leaching (B) in a separate system, e.g. in a one-step process utilizing a batch stirred tank reactor (BSTR), using a leach solution of concentrated H2SO4, H2O2 (50 wt%) and water. The Ni-MHP leaching (B) completely dissolves the Ni-MHP as fed and no solid residue is obtained after leaching (B). In this case, no additional separation step is required. However, if the Ni-MHP as fed does not completely dissolve, the solid residue obtained after Ni-MHP leaching (B) is separated from the leachate by filtration (C2). The BM leachate and the leachate from Ni-MHP leaching are then mixed together (D), for example in a BSTR, to obtain an aqueous metal sulfate-containing solution (MS-solution) rich in Ni and Co and / or Mn, containing the respective metals of interest and impurities in the form of sulfates, which may be further purified to produce battery grade metal sulfates for battery precursor synthesis. [Diagram 2]Figure 2 is a schematic flow chart showing another embodiment of the method according to the present disclosure, applying a series configuration, using BM as lithium-containing raw material and Ni-MHP as metal-based raw material. With reference to Figure 2, black mass obtained, for example, from crushed lithium-ion batteries containing Li and Ni, Co and / or Mn as target metals and metallic impurities such as Fe, Al, Cu, Zn, Mg, K and Ca, is first leached (E) by reductive acid leaching using a leaching solution of concentrated H2SO4, H2O2 (50 wt%) and water, for example in a continuous process utilizing a CSTR. By BM leaching (E), all target metals (Li and Ni, Co and / or Mn) and impurities contained in the BM are dissolved in the leachate (BM leachate) in the form of their sulfates, leaving mainly graphite as the undissolved fraction. The undissolved fraction is separated from the BM leachate by filtration (F1) and washed with water, if necessary, to remove the residues of the leachate. The BM leachate obtained after separation of the undissolved fraction is then mixed with Ni-MHP, which may contain Ni and Co and / or Mn as metals of interest, as well as metallic impurities such as Zn, Mg and Ca, for Ni-MHP leaching (G) by reductive acid leaching using the BM leachate, additional H2O2 (50 wt%) and water as leach solution, for example in a continuous process utilizing another CSTR. The Ni-MHP leaching (G) results in complete dissolution of the Ni-MHP feed and no solid residue is obtained after leaching (G). In this case, no additional separation steps are required. However, if the Ni-MHP feed is not completely dissolved, the solid residue obtained after Ni-MHP leaching (G) is separated from the leachate by filtration (F2). The leachate obtained after Ni-MHP leaching (G) and optional filtration step (F2) contains the respective metals of interest and impurities in the form of sulfates, forming a Ni and Co and / or Mn rich metal sulfate containing aqueous solution (MS-solution) which may be further purified to produce battery grade metal sulfates for battery precursor synthesis. [Diagram 3]Figure 3 is a schematic flow chart showing another embodiment of the method according to the present disclosure using BM as lithium-containing raw material, Ni-MHP as metal-based raw material, and an additional graphite leaching step. With reference to Figure 3, black mass obtained from, for example, crushed lithium-ion batteries containing Li and Ni, Co and / or Mn as target metals and metallic impurities such as Fe, Al, Cu, Zn, Mg, K and Ca is leached by reductive acid leaching using a leaching solution of concentrated H2SO4, H2O2 (50 wt%) and water, for example in a continuous process using a CSTR (H). By BM leaching (H), all target metals (Li and Ni, Co and / or Mn) and impurities contained in the BM are dissolved in the leachate (BM leachate) in the form of their sulfates, leaving mainly graphite as the undissolved fraction. The undissolved graphite fraction is separated from the BM leachate by filtration (I1). The separated graphite fraction is then leached by reductive acid leaching using a leaching solution of concentrated H2SO4, H2O2 (50 wt%) and water, for example in a continuous process using another CSTR (J). The target metals (Li as well as Ni, Co and / or Mn) and impurities still contained in the graphite are dissolved in the leachate in the form of their sulfates by graphite leaching (J), leaving behind undissolved graphite. The undissolved graphite is separated from the leachate by filtration (I2) and, after optional washing with water to remove residues of the leachate, high purity graphite is obtained, which may be used in an upcycling process, for example in the manufacture of anode materials. After separation of undissolved graphite, the leachate from graphite leaching (J) is then mixed with Ni-MHP, which may contain Ni and Co and / or Mn as metals of interest, as well as metallic impurities such as Zn, Mg and Ca, for Ni-MHP leaching (K) by reductive acid leaching using the leachate from graphite leaching (J), additional H2O2 (50 wt%) and water as leach solution, for example in a continuous process utilizing another CSTR. Ni-MHP leaching (K) completely dissolves the supplied Ni-MHP, and no solid residue is obtained after leaching (K). In this case, no additional separation step is required.However, if the Ni-MHP supplied does not dissolve completely, the solid residue obtained after Ni-MHP leaching (K) is separated from the leachate by filtration (I3). The BM leachate and the leachate obtained from Ni-MHP leaching are then mixed together (L), for example in a BSTR, to obtain an aqueous metal sulfate-containing solution (MS-solution) rich in Ni and Co and / or Mn, containing the respective metals of interest and impurities in the form of sulfates, which may be further purified to produce battery grade metal sulfates for battery precursor synthesis. [Figure 4]Figure 4 is a schematic flow chart showing another embodiment of the method according to the present disclosure using BM as lithium-containing raw material, Ni-MHP as metal-based raw material, and an additional graphite leaching step. With reference to Figure 4, black mass obtained from, for example, crushed lithium-ion batteries containing Li and Ni, Co and / or Mn as target metals and metallic impurities such as Fe, Al, Cu, Zn, Mg, K and Ca is leached (M) by reductive acid leaching using a leaching solution of concentrated H2SO4, H2O2 (50 wt%) and water, for example in a continuous process using a CSTR. By BM leaching (M), all target metals (Li and Ni, Co and / or Mn) and impurities contained in the BM are dissolved in the leachate (BM leachate) in the form of their sulfates, leaving mainly graphite as the undissolved fraction. The undissolved graphite fraction is separated from the BM leachate by filtration (N1). The separated graphite fraction is then leached by reductive acid leaching using a leaching solution of concentrated H2SO4, H2O2 (50 wt%) and water, for example in a continuous process using another CSTR (O). The target metals (Li as well as Ni, Co and / or Mn) and impurities still contained in the graphite are dissolved in the leachate in the form of their sulfates by graphite leaching (O), leaving behind undissolved graphite. The undissolved graphite is separated from the leachate by filtration (N2) and, after optional washing with water to remove residues of the leachate, high purity graphite is obtained, which may be used in an upcycling process, for example in the manufacture of anode materials. After separation of undissolved graphite, the BM leachate is mixed with the leachate from graphite leaching (O) and Ni-MHP, which may contain Ni and Co and / or Mn as metals of interest and metallic impurities such as Zn, Mg and Ca, is added for Ni-MHP leaching (P) by reductive acid leaching using the mixed leachate, additional H2O2 (50 wt%) and water as leach solution, for example in a continuous process utilizing a separate CSTR. Ni-MHP leaching (P) completely dissolves the supplied Ni-MHP and no solid residue is obtained after leaching (P). In this case, no additional separation step is required.However, if the supplied Ni-MHP does not dissolve completely, the solid residue obtained after Ni-MHP leaching (P) is separated from the leachate by filtration (N3). The leachate obtained after Ni-MHP leaching (P) and the optional filtration step (N3) contains the respective metals of interest and impurities in the form of sulfates, forming an aqueous metal sulfate-containing solution rich in Ni and Co and / or Mn (MS-solution), which may be further purified to produce battery grade metal sulfates for battery precursor synthesis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Detailed Description The technical solutions of the aspects of the present application are described in more detail below with reference to the drawings. It is clear that the described aspects are not all but some of the aspects of the present application. The features of various aspects can be combined to form further representative aspects of the present disclosure that may not be explicitly described or illustrated. All other aspects obtained by those skilled in the art based on the aspects of the present invention without creative efforts shall be within the protection scope of the present invention. Furthermore, the scope of the present invention is defined by the claims and their equivalents, so it shall be understood that the words and terms used in this specification are merely used to describe specific aspects and are not intended to be limiting.

[0016] The present disclosure provides a method for producing an aqueous metal-containing solution, comprising: To form a metal-containing aqueous solution, - subjecting the lithium-containing raw material to a first acid leach using a first leach solution to obtain a first leach solution; and - subjecting the raw metallic material to a second acid leaching using a second leach solution to obtain a second leachate. The present invention provides a method comprising:

[0017] The lithium-containing feedstock utilized in the first acid leaching may be selected from recycled feedstock materials, such as, for example, spent battery material. In a preferred embodiment, the lithium-containing feedstock is selected from recycled feedstock materials, collectively referred to herein as "black mass", including, but not limited to, materials derived from crushed lithium-ion batteries, particularly lithium-ion batteries utilizing lithium transition metal composite oxides as the positive electrode active material (so-called "NCM-based lithium-ion batteries"), or lithium-ion battery manufacturing scrap, particularly NCM-based lithium-ion battery manufacturing scrap, or combinations thereof.

[0018] In this application, the term "battery" is intended to include battery cells, battery modules that typically have multiple battery cells, and battery packs that typically have multiple battery modules. Additionally, in this application, the term "battery" is intended to include both disposable batteries and rechargeable (also called "secondary") batteries.

[0019] Battery shredding is usually a process step in battery recycling to recover valuable battery materials contained therein, especially cathode materials. Battery recycling usually starts with sorting discarded or used batteries according to their chemical composition and then crushing or shredding them to obtain battery materials of reduced size. Batteries contain various materials, including plastics and metals that make up the battery housing, separators, cathode and anode materials, and electrolytes. After shredding, a series of filtering and sieving steps are performed to separate the plastic and metal debris, and finally obtain as product the refined crushed battery material, so-called "black mass", which mainly contains cathode and anode materials, but may also contain, for example, electrolyte materials. However, because battery sorting is often difficult or not performed, the composition of the black mass usually varies depending on the type of battery being crushed.

[0020] The terms "positive electrode material" and "positive electrode active material" are used interchangeably to describe the material or metal that constitutes the main active component of the positive electrode. In lithium-ion batteries, lithium transition metal composite oxides or lithium iron phosphate (LiFePO4) containing the active metals nickel (Ni), cobalt (Co) and / or manganese (Mn) (so-called "NCM metals") are usually used as the positive electrode active material. General examples of lithium transition metal composite oxides include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), lithium nickel cobalt oxide (LiNi x Co 1-x O2 (0 < x < 1) or LiNi 1-x-y Co x Al y O2 ((0 < x ≤ 0.2, 0 < y ≤ 0.1)) and lithium nickel cobalt manganese (NCM) oxide (LiNi 1-x-y Co x Mn y O2 (0 < x + y < 1)).

[0021] The terms "negative electrode material" and "negative electrode active material" are used interchangeably to describe the material or metal that constitutes the main active component of the negative electrode. Usually, graphite powder is used as the negative electrode material in lithium-ion batteries. However, in this specification, the terms "negative electrode material" and "negative electrode active material" should be understood to include natural and artificial graphite, activated carbon, carbon black, conductive additives, lithium titanate (LTO), silicon, SiO x and silicon-based materials such as SiC, as well as high-performance powdered graphene.

[0022] The electrolyte in a lithium-ion battery is a liquid and typically contains a fluoride-containing salt, such as lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis((bistrifluoromethanesulfonyl)) (LiTFSI) or a lithium fluoroalkylphosphate, dissolved in an organic solvent, for example a mixture of C1-C6 alkyl carbonates, e.g., ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), propylene carbonate (PC), and the like.

[0023] Thus, black mass obtained from shredded lithium ion batteries and / or lithium ion battery manufacturing scrap typically contains Li and one or more of Ni, Co, and Mn. For example, the composition of black mass obtained from shredded lithium ion batteries may be about 28-40 wt.% Ni, Co, and / or Mn, about 3-5 wt.% Li, about 30-40 wt.% graphite, about 2-5 wt.% metallic impurities such as Al, Cu, Fe, and / or Mg, about 1-2 wt.% organic compounds, about 1 wt.% other impurities such as Ca, P, Si, Zn, K, and / or Na, and about 1-2 wt.% fluorides, although other compositions are possible.

[0024] According to a preferred embodiment of the process described herein, the lithium-containing feedstock utilized in the first acid leaching comprises, in addition to Li, one or more of Ni, Co and Mn, more preferably two or more of Ni, Co and Mn, even more preferably Ni, Co and Mn; more preferably it is black mass derived from crushed lithium-ion batteries, in particular crushed NCM-based lithium-ion batteries.

[0025] In a further preferred embodiment, the method of the present disclosure further comprises a step of preparing a lithium-containing raw material prior to the first acid leaching, which comprises crushing or shredding one or more lithium-ion batteries, in particular one or more NCM-based lithium-ion batteries, to obtain a black mass, in particular a black mass comprising lithium and one or more of the active metals nickel, cobalt and manganese. It should be noted that the method and apparatus for crushing or shredding the batteries are not particularly limited, and any method and apparatus suitable for crushing or shredding batteries and battery materials known to those skilled in the art can be used.

[0026] The metal-based feedstock for the second acid leaching is preferably a feedstock containing one or more of the metals nickel, cobalt and manganese, more preferably two or more of nickel, cobalt and manganese, even more preferably nickel, cobalt and manganese. The term "feedstock" is understood to mean a material that does not or has not functioned as a positive electrode material, for example a material that has essentially zero capacity for lithium intercalation / deintercalation in a Li-ion cell, such as a specific capacity of less than 50 mAh / g, preferably less than 25 mAh / g, even more preferably less than 10 mAh / g, or that has properties that dramatically reduce the lifespan of a Li-ion cell, such that the lifespan is reached when the capacity of the cell reaches 80% or less of the initial capacity, using a voltage cut-off appropriate for the electrode material in question, within 100 charge / discharge cycles, preferably within 50 charge / discharge cycles, even more preferably within 25 charge / discharge cycles. Suitable examples of raw materials include, but are not limited to, metal-bearing concentrates such as nickel sulfide concentrate or cobalt sulfide concentrate; mixed hydroxide precipitates (MHPs) such as mixed nickel hydroxide precipitates (Ni-based MHPs), mixed cobalt hydroxide precipitates (Co-based MHPs) or mixed manganese hydroxide precipitates (Mn-based MSPs) or combinations thereof such as mixed nickel-cobalt hydroxide precipitates; mixed sulfide precipitates (MSPs) such as mixed nickel sulfide precipitates (Ni-based MSPs), mixed cobalt sulfide precipitates (Co-based MSPs) or mixed manganese sulfide precipitates (Mn-based MSPs) or combinations thereof; matte such as nickel matte; nickel laterite; ferronickel; or combinations thereof. In a preferred embodiment, the metal-based raw materials are selected from MHPs, more preferably from mixed nickel hydroxide precipitates (Ni-based MHPs). In yet a further preferred embodiment of the method of the present disclosure, the metal-based raw materials for the second acid leaching are lithium-free. The use of such materials can make the method of the present disclosure more economically viable.

[0027] The terms mixed hydroxide precipitate (MHP) and mixed sulfide precipitate (MSP) are known to those skilled in the art of Li battery manufacturing. In particular, mixed hydroxide precipitation is a relatively recent large-scale industrial technology. For example, mixed nickel hydroxide precipitate (Ni-based MHP) is an intermediate product usually produced from processing nickel laterite or nickel sulfide ore by hydrometallurgical routes and contains nickel together with variable amounts of cobalt and / or manganese and further metals and / or impurities. Such materials are relatively cheap and available in large quantities, which may be preferred from the standpoint of economic viability.

[0028] The composition of the mixed nickel hydroxide precipitate (Ni-based MHP) suitable for use in the method of the present disclosure may typically be about 35-45 wt.% Ni, about 4-7 wt.% Mn, about 3-5 wt.% Co, about 2-3 wt.% impurities such as Mg, Ca, P, or Zn, and about 45-55 wt.% water, although other compositions are possible.

[0029] In a preferred embodiment, the lithium-containing raw material and the metal-based raw material are composed of distinctly different materials. In a further preferred embodiment, the lithium-containing raw material and the metal-based raw material contain different metals and / or molar ratios thereof from each other. By using different materials, different metals and / or different molar ratios of metals between the raw materials, it is possible to achieve metal-containing aqueous solutions with different metal contents and / or molar ratios of metals compared to the lithium-containing raw material. Preferably, this is achieved to compensate for the variable metal contents and / or molar ratios of metals in the lithium-containing raw material, which is preferably composed of black mass.

[0030] In a further preferred embodiment, the metals in the metal-containing aqueous solution include lithium and one or more of nickel, cobalt, and manganese. In a further preferred embodiment, the metals include lithium and two or more of nickel, cobalt, and manganese. In an even more preferred embodiment, the metals include lithium, nickel, cobalt, and manganese.

[0031] For the first acid leach, the lithium-containing feedstock is treated with a leach solution as described below with respect to embodiments of the method according to the present disclosure to dissolve lithium and other metals contained in the feedstock in their ionic form in the leach solution. Typically, the lithium-containing feedstock is leached under conditions to form an aqueous solution containing the respective metal salts, e.g. metal sulfates, as a leach solution.

[0032] Similarly, for the second acid leach, the raw metal-based material is treated with a leach agent as described below with respect to aspects of the method according to the present disclosure to dissolve the metals contained in the material in their ionic form in the leach solution. Typically, the raw metal-based material is leached under conditions to form an aqueous solution containing the respective metal salts, e.g. metal sulfates, as a leach solution.

[0033] It is to be understood that during the leaching operations described herein, not only the metals of interest, i.e. Li and the positive active metals Ni, Co and Mn, contained in the raw materials utilized, but also undesirable metals such as Cu, Mg or Na are transferred to the respective aqueous solutions / leachates, where they are dissolved as metal salts (e.g. metal sulfates such as uncrystallized lithium sulfate (Li2SO4), nickel sulfate (NiSO4), cobalt sulfate (CoSO4), manganese sulfate (MnSO4) etc.) and the leachates and aqueous solutions obtained from the leaching operations described herein also contain undesirable metals / metal salts (e.g. uncrystallized copper sulfate (CuSO4), magnesium sulfate (MgSO4), sodium sulfate (Na2SO4) etc.). The final content of the positive electrode active metals Ni, Co, Mn, other than Li, in the leachate and in the formed aqueous solution, as well as which undesirable metals are final, mainly depends on the composition of the raw material or black mass used, and their amounts or concentrations in the leachate or in the formed aqueous solution depend not only on the composition of the raw material or black mass used, but also on the conditions applied during the leaching operations described herein, including the first acid leaching and the second acid leaching.

[0034] According to a preferred embodiment, the acid leaching is carried out in the presence of an acid leaching reagent. That is, according to this preferred embodiment, the first leaching solution for the first acid leaching of the lithium-containing raw material and the second leaching solution for the second acid leaching of the metallic raw material contain an acid leaching reagent independently of each other. In this specification, "independently" means that the acid leaching reagent and its concentration can be selected independently for the first and second leaching solutions. The type of the acid leaching reagent for the first and second acid leaching is not particularly limited and can be selected from organic and inorganic acids as desired by a person skilled in the art.

[0035] Even more preferably, according to the method of the present disclosure, the acid leaching reagents associated with the first and second acid leaches are independently selected from sulfuric acid, nitric acid, hydrochloric acid, citric acid and combinations thereof, more preferably selected from sulfuric acid. The acid may be used as a concentrated acid or as an aqueous acid solution or a dilute acid, as appropriate. The concentration of the acid may vary over a wide range, for example from 0.1 to 98% by weight, preferably from 10 to 98% by weight.

[0036] According to a further preferred embodiment, the first acid leach is carried out in the presence of a reducing agent. According to a further preferred embodiment, the second acid leach is carried out in the presence of a reducing agent. The addition of a reducing agent may improve the leach yield and, if necessary, may bring the metal ions to the correct oxidation state. That is, according to this further preferred embodiment, either the first leach solution of the first acid leach of the lithium-containing raw material contains a reducing agent, the second leach solution of the second acid leach of the metallic raw material contains a reducing agent, or both the first and second leach solutions contain a reducing agent.

[0037] The reducing agent for the first and second acid leaching is not particularly limited and can be selected independently for these leaching operations. The preferred reducing agent for the first and second acid leaching is one that leaves no impurities based on metals other than metals, especially Ni, Co or Mn. Examples of reducing agents are organic reducing agents such as methanol, ethanol, sugar, ascorbic acid, urea, starch or cellulose, and inorganic reducing agents such as hydrazine and its salts such as sulfates and hydrogen peroxide. Hydrogen peroxide (H2O2) is the preferred reducing agent for the first and / or second acid leaching.

[0038] Thus, in an even more preferred embodiment, the first and / or second leaching solution comprises a reducing agent preferably selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose and combinations thereof, more preferably selected from hydrogen peroxide.

[0039] According to a further preferred embodiment of the method of the present disclosure, the total concentration of the target metal in the first leachate obtained by performing a first acid leach on the lithium-containing raw material and / or the second leachate obtained by performing a second acid leach on the metallic raw material is controlled to be in a range sufficiently lower than the solubility limit of each metal by the addition of water during the first acid leach and the second acid leach, respectively.

[0040] In this disclosure, the metals of interest are generally lithium and the positive electrode active metals nickel, cobalt and manganese, if present. This means that, as already indicated, not all of these metals must necessarily be present in the raw material used, except for lithium, which is essential in the lithium-containing raw material. For example, if the lithium-containing raw material used in the first acid leaching is derived from a LIB that uses lithium NCM oxide as the positive electrode active material, the metals of interest contained therein are Li, Ni, Co and Mn. For example, if the metallic base raw material used in the second acid leaching is MHP, the metals of interest contained therein are one or more of Ni, Co and Mn.

[0041] As used herein, the term "total concentration" should be understood to mean the sum of the concentrations of all metals of interest present in the respective leachate, e.g., if Li and Ni are the only metals of interest contained in the leachate, then the total concentration is the sum of the Ni and Li concentrations in the leachate, etc.

[0042] More preferably, the total concentration of the target metals, i.e. Li and preferably Ni, Co and / or Mn, in the first leachate obtained by subjecting the lithium-containing raw material to a first acid leach is controlled to be between 80 g / L and 120 g / L by the addition of water during the first acid leach.

[0043] More preferably, the total concentration of the target metal, preferably Ni, Co and / or Mn, in the second leachate obtained by subjecting the metallic raw material to the second acid leaching is controlled to be 80 g / L to 120 g / L by the addition of water during the second acid leaching.

[0044] Ensuring that the concentrations of the target metals leached from the feedstock are within these ranges ensures that they are within the solubility range of the respective metals in the first and second leach solutions even when optimal leaching conditions based on leaching yields of greater than 99% are achieved.

[0045] The amounts of acid leach reagent, in particular sulphuric acid, reducing agent, in particular hydrogen peroxide, and water added can be varied depending on the needs of the first and second acid leaches, for example when leaching metal-based raw materials the amount of reducing agent added in the second acid leach can be reduced if necessary to completely avoid leaching of impurities and certain metals such as manganese, or when leaching lithium-containing raw materials a higher leach yield of >99.9% of the NCM metals can be achieved by leaching with a higher concentration of acid leach reagent.

[0046] The process conditions for the leaching operations described herein, including the first acid leach, the second acid leach and the optional third acid leach described below, are not particularly limited and may be independently selected and may include leaching the feedstock under conditions such as pressure leaching or pressure oxidation, so long as the metals are provided as aqueous solutions of their salts, e.g., sulfates, to obtain metal-containing aqueous solutions. Preferably, according to the present disclosure, the leaching temperature is between 40°C and 60°C, independently for each leaching operation described herein. More preferably, according to the present disclosure, the leaching pressure is atmospheric pressure (about 1 bar), independently for each leaching operation described herein. More preferably, according to the present disclosure, the leaching time is between 10 minutes and 10 hours, preferably between 1 and 3 hours, independently for each leaching operation described herein.

[0047] The vessels or reactors for carrying out the leaching operations described herein, including the first acid leach, the second acid leach and the optional third acid leach described below, are not particularly limited as long as they are protected against (strong) acids. For example, a batch stirred tank reactor (BSTR) or a continuous stirred tank reactor (CSTR) may be used. In a preferred embodiment of the present disclosure, the acid leach of the lithium-containing feedstock (first acid leach) is carried out in a continuous process using a CSTR, the acid leach of the metallic feedstock (second acid leach) is carried out in a one-step process using a BSTR, and the third acid leach described below is carried out in a continuous process using another CSTR.

[0048] According to a first aspect of the method of the present disclosure, the first acid leaching of the lithium-containing raw material and the second acid leaching of the raw metal-based material are carried out in a parallel configuration, for example in separate vessels or reactors, as previously described with reference to Figure 1. The method according to this aspect further comprises mixing a first leachate from the first acid leaching of the lithium-containing raw material and a second leachate from the second acid leaching of the raw metal-based material to form an aqueous metal-containing solution.

[0049] By mixing the leachate (first leachate) obtained from leaching the lithium-containing raw material with the leachate (second leachate) obtained from leaching the metallic raw material, the content of the desired positive electrode active metals, such as Ni, Co and / or Mn, in the combined leachate (i.e., the formed metal-containing aqueous solution) can be selectively increased as required, while at the same time reducing the concentration of impurities compared to the leachate obtained from leaching only the lithium-containing raw material. In addition, the leaching of the metallic raw material and the mixing of the leachate make it possible to control the ratio of the desired positive electrode active metals, such as Ni, Co and / or Mn, in the combined leachate and compensate for the variation of these metals due to the nature and composition of the lithium-containing raw material.

[0050] Preferably, according to this aspect of the method according to the present disclosure, the first leach solution of the first acid leach of the lithium-containing feedstock comprises an acid leach reagent, preferably selected from sulfuric acid, nitric acid, hydrochloric acid, citric acid and combinations thereof, more preferably sulfuric acid, in stoichiometric excess, preferably in an amount of at least 5 wt. % in excess of the stoichiometric amount, more preferably between 8 wt. % and 65 wt. %, even more preferably between 8 wt. % and 43 wt. %, even more preferably between 15 wt. % and 25 wt. % in excess.

[0051] As used herein, the term "stoichiometric excess" in relation to the amount of acidic leaching reagent relates to the overall amount of metal of interest actually contained in the feedstock utilised in the leaching operation as defined herein, which amount is usually known and can be readily calculated, for example from manufacturer's specifications, prior to the leaching or recycling process.

[0052] Thus, according to this aspect, the first leach solution preferably comprises the acidic leach reagent in stoichiometric excess, preferably at least 5% by weight, more preferably 8% to 65% by weight, more preferably 8% to 43% by weight, even more preferably 15% to 25% by weight in excess of the stoichiometric amount (theoretically) required to leach / dissolve substantially all (more than 99%) of the target metals, i.e. Li and preferably the active metals Ni, Co and / or Mn, from the lithium-containing feedstock.

[0053] It has been found that within this excess amount of acid leaching reagent for the first acid leaching, the optimal leaching conditions in this embodiment can be obtained to ensure an optimal balance between maximum leaching yield of the metals of interest, i.e. Li and, if present, Ni, Co and / or Mn, from the lithium-containing feedstock and minimum consumption of leaching reagent. That is, if the excess amount of acid leaching reagent for the first acid leaching relative to the lithium-containing feedstock is below the above range, the leaching yield from the feedstock is low. If the excess amount of acid leaching reagent for the first acid leaching is above the above range, the consumption of acid leaching reagent increases without further significantly increasing the leaching yield of the metals of interest from the feedstock.

[0054] In this application, the leaching yield is calculated according to the formula: Leaching yield (%) = (1 - amount of target metal in residual solids (g) / amount of target metal in feedstock (g)) x 100 is defined as:

[0055] Preferably, according to this aspect, independently of the first leach solution, the second leach solution for the second acid leaching of the metallic raw material comprises an acid leach reagent, preferably selected from sulphuric acid, nitric acid, hydrochloric acid, citric acid and combinations thereof, more preferably sulphuric acid, in an amount between 0 wt. % (i.e. the stoichiometric amount of the acid leach reagent but not in excess) and 10 wt. % in excess of the stoichiometric amount, more preferably between 0 wt. % and 5 wt. % in excess of the stoichiometric amount.

[0056] Thus, according to this aspect, the second leach solution preferably comprises 0% to 10% by weight, more preferably 0% to 5% by weight, in excess of the stoichiometric amount (theoretically) required to leach / dissolve substantially all (>99%) of the target metal, preferably Ni, Co and / or Mn, from the raw metallic base material.

[0057] It has been found that the amount of excess acid leaching reagent for the second acid leach may be at most slight, providing optimal leaching conditions that ensure complete dissolution of the raw metal-based material (i.e. substantially no solid residue after leaching) while minimizing consumption of leaching reagent.

[0058] As previously explained, it may be preferred to carry out the first and / or second acid leach in the presence of a reducing agent.

[0059] More preferably, according to this aspect of the method of the present disclosure, the first leach solution of the first acid leach of the lithium-containing raw material comprises 2% to 7% by volume of the reducing agent, preferably 3% to 7% by volume, even more preferably 2.5% to 6% by volume, preferably 4% to 6% by volume, based on the total volume of the first leach solution. As explained above, the reducing agent for the first acid leach is not particularly limited, but is preferably selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose and combinations thereof, more preferably hydrogen peroxide.

[0060] It has been found that this amount of reducing agent in the first acid leach of the lithium-containing feedstock has the advantage that it allows reducing the amount of acid leach chemicals required while at the same time ensuring optimal conditions based on maximizing the leaching yield of the metals of interest, i.e. Li and, if present, Ni, Co and / or Mn, from the lithium-containing feedstock.

[0061] More preferably, according to this embodiment, the second leaching solution for the second acid leaching of the metallic raw material, independent of the first leaching solution, contains 0.1% to 3% by volume of a reducing agent, more preferably 0.1% to 1.5% by volume, even more preferably 0.5% to 1.5% by volume, based on its total volume. As explained above, the reducing agent for the second acid leaching is not particularly limited, but is preferably selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose and combinations thereof, more preferably hydrogen peroxide. In another preferred embodiment, the second leaching solution does not contain a reducing agent.

[0062] The addition of a reducing agent to the second acid leach of the raw metal-based material has been found to have the advantage that it can reduce the amount of acid leach chemicals required while at the same time ensuring optimal conditions for complete dissolution of the raw metal-based material (i.e. substantially no solid residue after leaching).

[0063] Thus, according to this aspect of the disclosed method, the first leach solution for the first acid leach of the lithium-containing raw material contains an acid leach reagent, preferably sulfuric acid, in an amount of at least 5 wt. % above the stoichiometric amount, more preferably between 8 wt. % and 65 wt. %, more preferably between 8 wt. % and 43 wt. %, even more preferably between 15 wt. % and 25 wt. % in excess of the stoichiometric amount, and an acid leach reagent, preferably sulfuric acid, in an amount of at least 2 vol. % to 7 vol. %, preferably between 3 vol. % to 7 vol. %, even more preferably between 2.5 vol. % to 6 vol. %, preferably between 4 vol. % to 5 vol. %, more preferably between 5 vol. % to 6 vol. %, even more preferably between 5 vol. % to 7 vol. %, based on the total volume of the first leach solution. It is even more preferred that the second leaching solution for the second acid leaching of the metallic raw material contains 0.1% to 3% by volume, more preferably 0.1% to 3% by volume, and even more preferably 0.5% to 1.5% by volume of a reducing agent, preferably hydrogen peroxide, based on the total volume of the acid leaching reagent, preferably sulfuric acid, and the second leaching solution in an amount of 0% to 10% by weight, more preferably 0% to 5% by weight in excess of the stoichiometric amount.

[0064] According to a first aspect of the method of the present disclosure, the pH of the first leachate obtained from the first acid leaching of the lithium-containing raw material may be 0.2 to 0.5, for example 0.3 to 0.5, and the pH of the second leachate obtained from the second acid leaching of the metallic raw material may be 1.0 to 1.5. According to this aspect, the pH of the combined leachate, i.e., the metal-containing aqueous solution formed after mixing the first and second leachates, may be 0.7 to 1, preferably 0.8 to 1.

[0065] This means that by mixing the leachate (first leachate) obtained by leaching the lithium-containing raw material with the leachate (second leachate) obtained by leaching the metallic raw material, the pH of the resulting combined leachate (i.e., the formed metal-containing aqueous solution) is advantageously increased without the addition of additional base or basic compound compared to when only the lithium-containing raw material is leached (i.e., the metallic raw material is not subjected to a second acid leach), while the content of the desired positive electrode active metals, such as Ni, Co and / or Mn, can be selectively increased as required, and the concentration of impurities, such as Cu, Mg or Na, can be reduced in the combined leachate, as previously described.

[0066] Even more preferably, according to this aspect of the disclosed method, the concentration of the resulting combined leachate (ie, the formed metal-containing aqueous solution) may be between 1.1 and 1.6, more preferably between 1.2 and 1.4 g / mL.

[0067] Thus, according to the first aspect previously described, the present disclosure provides in a particularly preferred aspect a method for producing an aqueous metal-containing solution, comprising the steps of: - subjecting the lithium-containing raw material to a first acid leach using a first aqueous leach solution comprising an acid leach reagent and a reducing agent to obtain a first leach solution; - subjecting the raw metal material to a second acid leaching using a second aqueous leaching solution comprising an acid leaching reagent and a reducing agent to obtain a second leachate; and - mixing the first leachate from the first acid leach and the second leachate from the second acid leach to form a metal-containing aqueous solution. The present invention provides a method comprising:

[0068] The preferred leaching conditions previously described also apply to this particularly preferred method.

[0069] According to a second aspect of the process according to the present disclosure, the first acid leaching of the lithium-containing feedstock and the second acid leaching of the metallic base feedstock are carried out in a series configuration, for example in separate vessels or reactors, as previously described with reference to FIG.

[0070] According to this embodiment, the lithium-containing raw material is first subjected to acid leaching, and the first leachate obtained from the first acid leaching, which contains the metal leached from the lithium-containing raw material as a result, is then used as a second leachate solution for the second acid leaching of the metal-based raw material. According to this embodiment, the leachate (second leachate) produced by leaching the metal-based raw material, which contains the metal leached from the lithium-containing raw material and the metal (i.e., from the first and second leaching operations), as a result, forms a metal-containing aqueous solution.

[0071] Preferably, according to this aspect of the method according to the present disclosure, the first leach solution of the first acid leach of the lithium-containing feedstock comprises an acid leach reagent, preferably selected from sulfuric acid, nitric acid, hydrochloric acid, citric acid and combinations thereof, more preferably sulfuric acid, in an amount at least 20% by weight in excess of the stoichiometric amount, preferably between 20% by weight and 65% by weight, more preferably between 20% by weight and 60% by weight, even more preferably between 20% by weight and 65% by weight, even more preferably between 50% by weight and 60% by weight.

[0072] Thus, according to this preferred aspect, the first leach solution comprises an amount of acidic leach reagent in excess of 20% by weight or more, preferably 20% to 65% by weight, more preferably 20% to 60% by weight, even more preferably 20% to 65% by weight, even more preferably 50% to 60% by weight, of the stoichiometric amount (theoretically) required to leach / dissolve substantially all (>99%) of the metals of interest, i.e. Li and preferably Ni, Co and / or Mn, from the lithium-containing feedstock.

[0073] It has been found that within this excess amount of acid leaching reagent for the first acid leaching, optimal leaching conditions can be obtained in this embodiment to ensure maximum leaching yield of the metals of interest, i.e. Li and, if present, Ni, Co and / or Mn, from the lithium-containing feedstock, while allowing modification and control of the leaching conditions for the second acid leaching of the metal-based feedstock, if required.

[0074] As previously explained, it may be preferred to carry out the first and / or second acid leach in the presence of a reducing agent.

[0075] More preferably, according to the second aspect of the method of the present disclosure, the first leach solution for the first acid leach of the lithium-containing raw material comprises 3% to 5% by volume of a reducing agent relative to its total volume. As explained above, the reducing agent for the first acid leach is not particularly limited, but is preferably selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose and combinations thereof, more preferably hydrogen peroxide.

[0076] In this embodiment, it has been found that such an amount of reducing agent in the first acid leach of the lithium-containing raw material has the advantage that it allows a reduction in the amount of acid leach chemicals required while at the same time ensuring optimal conditions based on maximizing the leaching yield of the metals of interest, i.e. Li and, if present, Ni, Co and / or Mn, from the lithium-containing raw material.

[0077] Therefore, according to this aspect of the method of the present disclosure, it is even more preferred that the first leach solution of the first acid leach of the lithium-containing raw material comprises an acid leach reagent, preferably sulfuric acid, in an amount of at least 20 wt. % above the stoichiometric amount, preferably 20 wt. % to 65 wt. %, more preferably 20 wt. % to 60 wt. %, even more preferably 20 wt. % to 65 wt. %, even more preferably 50 wt. % to 60 wt. % excess, and an acid leach reagent, preferably hydrogen peroxide, in an amount of 3 vol. % to 5 vol. %, based on the total volume of the first leach solution.

[0078] As explained above, according to the second aspect of the method of the present disclosure, the leachate (first leachate) obtained from the leaching of the lithium-containing raw material is used as a leach solution (second leach solution) for the second acid leach of the metallic raw material. As a result, the second leach solution in this aspect contains not only the metal leached from the lithium-containing raw material, but also the acid leach reagent used to perform the first acid leach as the acid leach reagent, preferably sulfuric acid, and optionally a reducing agent and water if added in the first acid leach.

[0079] However, according to this aspect of the disclosed method, even when optimal leaching conditions based on a leaching yield of greater than 99% are achieved, it may still be preferred to add water during the second acid leach to ensure that the total concentration of the target metals in the second leachate obtained by performing the second acid leach on the raw metal-based material using the first leachate as the second leach solution is controlled to be well below the solubility of the respective metals, more preferably between 80 g / L and 120 g / L, during the second acid leach to ensure that the total concentration of the target metals in the second leachate is within the solubility range of the respective metals, more preferably between 80 g / L and 120 g / L.

[0080] Also, according to this aspect of the disclosed method, it may be further preferred to add an additional reducing agent, preferably selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose and combinations thereof, more preferably selected from hydrogen peroxide, particularly in an amount such that the second leach solution of the second acid leaching of the raw metal-based raw material contains 0.4% to 0.8% by volume of the reducing agent relative to its total volume. In another preferred aspect, the second leach solution does not contain a reducing agent.

[0081] In this embodiment, the addition of a reducing agent to the second acid leaching of the raw metal-based material has been found to have the advantage that it can reduce the amount of acid leaching chemicals required while at the same time ensuring optimal conditions for complete dissolution of the raw metal-based material (i.e. substantially no solid residue after leaching).

[0082] According to a second aspect of the method of the present disclosure, the pH of the first leachate resulting from the first acid leaching of the lithium-containing raw material may be between 0.1 and 0.4. After the second acid leaching of the metallic raw material using the first leachate as the second leach solution, the resulting second leachate forming a metal-containing aqueous solution due to consumption of free acid by ions present in the metallic raw material, such as hydroxide ions, may have a pH between 0.8 and 1. In an aspect, the pH may be between 0.8 and 1.6, preferably between 1 and 1.6.

[0083] More preferably, according to this aspect of the method of the present disclosure, the concentration of the resulting second leachate forming the metal-containing aqueous solution may be between 1.1 and 1.6, more preferably between 1.2 and 1.4 g / mL.

[0084] Therefore, this aspect of the method according to the present disclosure, which applies a series configuration for a first acid leaching of a lithium-containing raw material and a second acid leaching of a metallic raw material, has the advantage that, compared to the case where only the lithium-containing raw material is leached (i.e., the metallic raw material is not subjected to a second acid leaching) as described above, the pH of the resulting metal-containing aqueous solution can be increased without adding additional base or basic compound, and at the same time, the content of the positive electrode active metals Ni, Co and / or Mn can be selectively increased as required, and the concentration of impurities such as Cu, Mg or Na in the resulting aqueous solution can be reduced.

[0085] More advantageously, the series configuration allows for a reduction in the consumption of chemicals, particularly the acid leaching reagent and the reducing agent. In particular, this series configuration allows for the addition of more acid in the first leaching stage, for example the amount of acid required to leach the raw metal-based raw material in addition to the excess acid added for leaching the lithium-containing raw material, allowing for an increase in the leaching yield of the metals of interest, i.e. Li and, if present, Ni, Co and / or Mn, from the lithium-containing raw material, while at the same time controlling the leaching yield from the raw metal-based raw material by adding a smaller amount of reducing agent, thereby completely avoiding the leaching of impurities from the leaching of the raw metal-based raw material. In addition, the leaching of the raw metal-based raw material allows for the control of the ratio of the desired positive electrode active metals, such as Ni, Co and / or Mn, in the resulting leachate (i.e., metal-containing aqueous solution), and for compensating for the variation of these metals due to the nature and composition of the lithium-containing raw material.

[0086] Thus, according to the second aspect previously described, the present disclosure provides in a particularly preferred aspect a method for producing an aqueous metal-containing solution, comprising the steps of: - subjecting the lithium-containing raw material to a first acid leach using a first aqueous leach solution comprising an acid leach reagent and a reducing agent to obtain a first leach solution; and - subjecting the raw metallic material to a second acid leaching using the second aqueous leaching solution to obtain a second leachate. wherein a first leachate from a first acid leach is used as a second aqueous leach solution for a second acid leach, the resulting second leachate forming an aqueous metal-containing solution.

[0087] The preferred leaching conditions previously described also apply to this particularly preferred method.

[0088] In a further preferred embodiment of the method of the present disclosure, the method may further comprise a step of filtering the first leachate obtained from the first acid leaching of the lithium-containing raw material to separate the undissolved fraction from the first leachate. Filtration of the leachate obtained from leaching the lithium-containing raw material may be carried out especially when the lithium-containing raw material is material from crushed lithium-ion batteries, i.e. black mass, since such material contains insoluble components (i.e. elements / metals that are not dissolved in the acid leaching solution during leaching), mainly anode materials such as graphite, silicon or silicon-based materials.

[0089] The method and device for filtering and separating the undissolved fraction are not particularly limited, and filtering methods and devices known to those skilled in the art, such as the use of a filter press, can be applied as necessary.

[0090] The separated undissolved fraction may be discarded or recycled and reused, for example, in the production of anode materials for batteries. However, the separated undissolved fraction obtained after the leaching process may still contain trace amounts of metals, including metals of interest such as Li and the cathode active metals Ni, Co and Mn, for example, in amounts of 2-6 wt.%.

[0091] Therefore, the separated undissolved fraction may be subjected to a further acid leaching (also referred to herein as a "third" acid leaching) in order to reduce the content of residual metals in the separated undissolved fraction, e.g. to produce high purity graphite, silicon or silicon-based material of a quality that can be used in an upcycling process in the manufacture of anode materials with minimal pre-treatment steps, as well as to increase the overall leaching yield of the metals of interest, i.e. Li and, if present, Ni, Co and / or Mn, from the feedstock.

[0092] The same process conditions as previously described for the first and second acid leaches may be applied to carry out an acid leach on the separated undissolved fraction.

[0093] Therefore, in an even more preferred embodiment, the method of the present disclosure further comprises subjecting the separated undissolved fraction to acid leaching to obtain a leachate, wherein the leachate solution for acid leaching of the separated undissolved fraction comprises an acid leaching reagent and a reducing agent.

[0094] The acid leaching reagents associated with the acid leaching of the separated undissolved fraction are preferably independently selected from sulfuric acid, nitric acid, hydrochloric acid, citric acid and combinations thereof, more preferably sulfuric acid, including the respective concentrated and dilute acids or aqueous acid solutions. The concentration of the acid may vary over a wide range, for example from 0.1 to 98% by weight, preferably from 10 to 98% by weight.

[0095] The reducing agent associated with the acid leaching of the separated undissolved fraction is not particularly limited, but is preferably independently selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose, and combinations thereof, more preferably hydrogen peroxide.

[0096] More preferably, the leaching solution for the acid leaching of the separated undissolved fraction contains an acid leaching reagent in an amount of at least 20% by weight, preferably 20% to 30% by weight, in excess of the stoichiometric amount.

[0097] It should be understood that in the context of leaching of the undissolved fraction, "in excess of the stoichiometric amount" relates to the overall amount of residual metals of interest, i.e. Li and preferably Ni, Co and / or Mn, actually contained in the separated undissolved fraction utilized for leaching.

[0098] More preferably, the leaching solution for the acid leaching of the separated undissolved fraction contains 0.1 vol % to 3 vol %, more preferably 0.5 vol % to 1.5 vol %, of the reducing agent relative to its total volume.

[0099] It has been found that such an amount of reducing agent for the acid leaching of the separated undissolved fraction has the advantage that it allows to reduce the overall amount of acid leaching chemicals required while at the same time ensuring optimal conditions based on maximizing the leaching yield of the metals of interest, i.e. Li and, if present, Ni, Co and / or Mn, from the separated undissolved fraction.

[0100] More preferably, the total concentration of the metals of interest, i.e. Li and preferably the active metals Ni, Co and / or Mn, in the leachate resulting from acid leaching of the separated undissolved fraction is controlled to be in a range well below the solubility of the respective metals, more preferably between 80 g / L and 120 g / L, by adding water during acid leaching of the separated undissolved fraction to ensure that it is within the solubility range of the respective metals at optimal leaching conditions based on a leaching yield of more than 99%.

[0101] According to the third embodiment as previously described with reference to FIG. 3, the method of the present disclosure further comprises filtering the first leachate obtained from the first acid leaching of the lithium-containing feedstock to separate an undissolved fraction, such as graphite, silicon or silicon-based material, and subjecting the separated undissolved fraction to acid leaching to obtain a leachate as described above.

[0102] The separated undissolved fraction may be leached, followed by filtration, and the solid residue may be washed with water to obtain a leachate.

[0103] According to a third aspect of the method of the present disclosure, the leachate obtained from the acid leaching of the separated undissolved fraction, which contains the metals leached from the separated undissolved fraction, is then used as a second leach solution for a second acid leaching of the raw metal-based material. The leachate (second leachate) produced by leaching the raw metal-based material with the leachate obtained from the acid leaching of the separated undissolved fraction, which contains the metals leached from the separated undissolved fraction and the raw metal-based material, is finally mixed with the first leachate obtained from the first acid leaching of the lithium-containing material to form a metal-containing aqueous solution.

[0104] Preferably, according to this aspect of the method according to the present disclosure, the first leach solution of the first acid leach of the lithium-containing feedstock comprises an acid leach reagent, preferably selected from sulfuric acid, nitric acid, hydrochloric acid, citric acid and combinations thereof, more preferably sulfuric acid, in excess of the stoichiometric amount, preferably in an amount of at least 5 wt. % in excess of said stoichiometric amount, more preferably in an amount between 8 wt. % and 65 wt. %, more preferably in an amount between 8 wt. % and 43 wt. %, even more preferably in an amount between 15 wt. % and 25 wt. % in excess.

[0105] Thus, according to this preferred aspect of the method according to the present disclosure, the first leach solution comprises the acidic leach reagent in a stoichiometric excess, preferably in an amount of at least 5 wt.%, more preferably between 8 wt.% and 65 wt.%, more preferably between 8 wt.% and 43 wt.%, even more preferably between 15 wt.% and 25 wt.% in excess of the stoichiometric amount (theoretical) required to leach / dissolve substantially all (more than 99%) of the target metals, i.e. Li and preferably Ni, Co and / or Mn, from the lithium-containing feedstock, and the leach solution for the acid leaching of the separated undissolved fraction comprises the acidic leach reagent in an amount of at least 20 wt.%, preferably between 20 wt.% and 30 wt.% in excess of the stoichiometric amount (theoretical) required to leach / dissolve substantially all (more than 99%) of the target metals, i.e. Li and preferably the active metals Ni, Co and / or Mn, from the separated undissolved fraction.

[0106] It has been found that within this excess of acid leaching reagent for the first acid leaching and for the acid leaching on the separated undissolved fraction, optimal leaching conditions can be obtained in both cases to ensure an optimal balance between maximum leaching yield of the metals of interest, i.e. Li and NCM metals, if present, from the lithium-containing feedstock and the separated undissolved fraction, and minimum consumption of leaching reagent.

[0107] More preferably, according to this aspect of the method according to the present disclosure, the first leach solution of the first acid leach of the lithium-containing raw material comprises from 2 vol.% to 7 vol.%, preferably from 3 vol.% to 7 vol.%, even more preferably from 2.5 vol.% to 6 vol.%, preferably from 4 vol.% to 6 vol.%, of reducing agent relative to its total volume.

[0108] As explained above, the reducing agent for the first acid leaching and / or the acid leaching of the separated undissolved fraction is not particularly limited, but is preferably selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose and combinations thereof, more preferably hydrogen peroxide.

[0109] Thus, according to this aspect of the disclosed method, the first leach solution for the first acid leach of the lithium-containing raw material contains an acid leach reagent, preferably sulfuric acid, in an amount of at least 5 wt. % above the stoichiometric amount, more preferably between 8 wt. % and 65 wt. %, more preferably between 8 wt. % and 43 wt. %, even more preferably between 15 wt. % and 25 wt. % excess, based on the total volume of the first leach solution, of 2 vol. % to 7 vol. %, preferably between 3 vol. % and 7 vol. %, even more preferably between 2.5 vol. % and 6 ... more preferably between 3 vol. % and 7 vol. %, It is even more preferred that the leaching solution for acid leaching of the separated undissolved fraction contains an acid leaching reagent, preferably sulfuric acid, in an amount of at least 20% by weight, preferably 20% by weight to 30% by weight in excess of the stoichiometric amount, and 0.1% by volume to 3% by volume, more preferably 0.5% by volume to 1.5% by volume of the reducing agent, preferably hydrogen peroxide, based on the total volume of the leaching solution used to leach the separated undissolved fraction.

[0110] By applying these leaching conditions, it is possible to achieve leaching yields of more than 99%, even more than 99.9%, of the target metals, i.e. Li and, if present, Ni, Mn and / or Co, from the lithium-containing feedstock, while reducing the amount of metals contained in the separated undissolved fraction containing the target metals, Li, Ni, Co and / or Mn, to less than 1 wt.%, preferably less than 0.5 wt.%, more preferably even less than 0.1 wt.%.

[0111] As explained above, according to the third aspect of the method of the present disclosure, the leachate obtained from the acid leaching of the separated undissolved fraction is used as a leach solution (second leach solution) for the second acid leaching of the raw metal-based material. As a result, the second leach solution in this aspect contains not only the metal leached from the separated undissolved fraction, but also the acid leaching reagent used to perform acid leaching of the separated undissolved fraction as an acid leaching reagent, preferably sulfuric acid, and optionally a reducing agent and, if used, water.

[0112] However, according to this aspect of the disclosed method, even when optimal leaching conditions based on a leaching yield of greater than 99% are achieved, it may still be preferred to add water during the second acid leaching to ensure that the total concentration of the target metals in the second acid leaching solution obtained by performing a second acid leaching on the raw metal-based material using the leachate from leaching the separated undissolved fraction as the second leach solution is controlled to be well below the solubility of the respective metals, more preferably between 80 g / L and 120 g / L, in order to ensure that the total concentration of the target metals in the second acid leaching solution is within the solubility range of the respective metals, more preferably between 80 g / L and 120 g / L.

[0113] According to a third aspect of the method of the present disclosure, the pH of the first leachate obtained from the first acid leaching of the lithium-containing raw material may be 0.2 to 0.5, for example 0.3 to 0.5, and the pH of the leachate obtained from the acid leaching of the separated undissolved fraction may be 0 to 0.3. After performing the second acid leaching of the metallic raw material using the leachate obtained from the leaching of the separated undissolved fraction as the second leach solution, the pH of the second leachate formed due to consumption of free acid by ions present in the metallic raw material, for example hydroxide ions, may be 1.0 to 1.6, for example 1.0 to 1.4. According to this aspect, the pH of the combined leachate, i.e., the metal-containing aqueous solution formed after mixing the first and second leachates, may be 1.2 to 1.5. In this aspect, the pH may be 0.8 to 1.5.

[0114] Even more preferably, according to this aspect of the disclosed method, the concentration of the resulting combined leachate (ie, the formed metal-containing aqueous solution) may be between 1.1 and 1.6, more preferably between 1.2 and 1.4 g / mL.

[0115] Therefore, this aspect of the method according to the present disclosure, which applies the mixing of the leachate (first leachate) obtained by acid leaching of the separated undissolved fraction and leaching of the lithium-containing raw material with the leachate (second leachate) obtained by leaching of the metallic raw material, has the advantage that the pH of the resulting metal-containing aqueous solution can be increased without the addition of additional bases or basic compounds, compared to the case where only the lithium-containing raw material is leached (i.e., no second acid leaching of the metallic raw material is performed). At the same time, the leaching yield of the desired positive electrode active metals such as Ni, Co and / or Mn can be increased, and their contents can be selectively increased as required, while the concentration of impurities such as Cu, Mg or Na in the resulting aqueous solution can be reduced by leaching of the metallic raw material and the separated undissolved fraction.

[0116] More advantageously, this aspect of the disclosed method allows for control of the leaching yield from the raw metal-based raw material by adding less reducing agent and acidic leaching reagent, thereby completely avoiding leaching of impurities from the leaching of the raw metal-based raw material and reducing chemical consumption. In addition, leaching of the raw metal-based raw material allows for control of the ratio of desired cathode active metals, such as Ni, Co and / or Mn, in the resulting leachate (i.e., metal-containing aqueous solution) and compensates for the variation of these metals due to the nature and composition of the lithium-containing raw material.

[0117] Furthermore, this aspect of the method according to the present disclosure can reduce the content of metals in the final separated undissolved fraction to produce graphite, silicon or silicon-based materials of a quality that can be utilized in upcycling processes in the manufacture of anode materials with minimal pre-treatment steps, for example.

[0118] According to the third aspect described above, the present disclosure provides in a particularly preferred aspect a method for producing an aqueous metal-containing solution, comprising the steps of: - subjecting the lithium-containing raw material to a first acid leach using a first aqueous leach solution comprising an acid leach reagent and a reducing agent to obtain a first leach solution; - filtering the first leachate from the first acid leach to separate the undissolved fraction; - subjecting the separated undissolved fraction to acid leaching using an aqueous leaching solution containing an acid leaching reagent and a reducing agent to obtain a leachate; - subjecting the raw metallic material to a second acid leaching using a second aqueous leaching solution to obtain a second leachate; and - mixing the first leachate from the first acid leach and the second leachate from the second acid leach to form a metal-containing aqueous solution. Including, The method comprises using the leachate obtained from the acid leaching of the separated undissolved fraction as a second aqueous leach solution for a second acid leach.

[0119] The preferred leaching conditions previously described also apply to this particularly preferred method.

[0120] According to the fourth embodiment as previously described with reference to FIG. 4, the method of the present disclosure further comprises filtering the first leachate obtained from the first acid leaching of the lithium-containing feedstock to separate an undissolved fraction, such as graphite, silicon or silicon-based material, and subjecting the separated undissolved fraction to acid leaching to obtain a leachate as described above.

[0121] The separated undissolved fraction may be leached, followed by filtration, and the solid residue may be washed with water to obtain a leachate.

[0122] According to a fourth aspect of the method of the present disclosure, the method further comprises the step of mixing the first leachate obtained from the first acid leaching of the lithium-containing raw material with the leachate obtained from the acid leaching of the separated undissolved fraction to obtain a mixed leachate containing the metals leached from the lithium-containing raw material and the separated undissolved fraction. The mixed leachate thus obtained is then used as a second leachate for the second acid leaching of the metal-based raw material. According to this aspect, the leachate (second leachate) produced by leaching the metal-based raw material with the mixed leachate containing the metals leached from the lithium-containing raw material, the separated undissolved fraction and the metals (i.e., from all three leaching operations) forms a metal-containing aqueous solution.

[0123] Preferably, according to this aspect of the method according to the present disclosure, the first leach solution of the first acid leach of the lithium-containing feedstock comprises an acid leach reagent, preferably selected from sulfuric acid, nitric acid, hydrochloric acid, citric acid and combinations thereof, more preferably sulfuric acid, in excess of the stoichiometric amount, preferably in an amount of at least 5 wt. % in excess of said stoichiometric amount, more preferably in an amount between 8 wt. % and 65 wt. %, more preferably in an amount between 8 wt. % and 43 wt. %, even more preferably in an amount between 15 wt. % and 25 wt. % in excess.

[0124] More preferably, according to this aspect of the method according to the present disclosure, the first leach solution for the first acid leaching of the lithium-containing raw material comprises 2% to 7% by volume, preferably 3% to 7% by volume, even more preferably 2.5% to 6% by volume, preferably 4% to 6% by volume of the reducing agent relative to its total volume. As explained above, the reducing agent for the first acid leaching and / or the acid leaching of the separated undissolved fraction is not particularly limited, but is preferably selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose and combinations thereof, more preferably hydrogen peroxide.

[0125] Thus, according to this aspect of the disclosed method, the first leach solution for the first acid leach of the lithium-containing raw material contains an acid leach reagent, preferably sulfuric acid, in an amount of at least 5 wt. % above the stoichiometric amount, more preferably 8 wt. % to 65 wt. %, more preferably 8 wt. % to 43 wt. %, even more preferably 15 wt. % to 25 wt. % in excess of the stoichiometric amount, and an acid leach reagent, preferably sulfuric acid, in an amount of at least 2 vol. % to 7 vol. %, preferably 3 vol. % to 7 vol. %, even more preferably 2.5 vol. % to 6 vol. %, more preferably 10 vol. % to 20 vol. %, more preferably 15 vol. % to 25 vol. %, more preferably 10 vol. % to 20 ... It is even more preferable that the leaching solution for acid leaching of the separated undissolved fraction contains an acid leaching reagent, preferably sulfuric acid, in an amount 20% by weight or more, preferably 20% by weight to 30% by weight in excess of the stoichiometric amount, and 0.1% by volume to 3% by volume, more preferably 0.5% by volume to 1.5% by volume of a reducing agent, preferably hydrogen peroxide, based on the total volume of the leaching solution used to leach the separated undissolved fraction.

[0126] By applying these leaching conditions, it is possible to achieve leaching yields of more than 99%, even more than 99.9%, of the target metals, i.e. Li and, if present, Ni, Co and / or Mn, from the lithium-containing feedstock, while reducing the amount of metals contained in the separated undissolved fraction containing the target metals, Li, Ni, Co and / or Mn, to less than 1 wt.%, preferably less than 0.5 wt.%, more preferably even less than 0.1 wt.%.

[0127] As previously described, according to the fourth aspect of the method of the present disclosure, the mixed leach solution is used as a second leach solution for the second acid leach of the metallic raw material, so that it contains not only the metals leached from the lithium-bearing raw material and the separated undissolved fraction, but also the acid leach reagent used to carry out the acid leach of the lithium-bearing raw material (first acid leach) and the acid leach of the separated undissolved fraction, respectively, preferably sulphuric acid, and optionally a reducing agent and, if used, water.

[0128] However, according to this aspect of the disclosed method, even when optimal leaching conditions based on a leaching yield of greater than 99% are achieved, it may still be preferred to add additional water during the second acid leach to ensure that the metals are within their solubility range, in particular to control the total concentration of the target metals in the second leachate obtained by performing the second acid leach on the raw metal-based material using the mixed leachate as the second leach solution to be well below the solubility of the respective metals, more preferably between 80 g / L and 120 g / L.

[0129] According to a fourth aspect of the method of the present disclosure, the pH of the first leachate obtained from the first acid leaching of the lithium-containing raw material may be 0.2 to 0.5, for example 0.3 to 0.5, and the pH of the leachate obtained from the acid leaching of the separated undissolved fraction may be 0 to 0.3. The pH of the mixed leachate obtained after mixing the first leachate obtained from the first acid leaching and the leachate obtained from the acid leaching of the separated undissolved fraction may be 0.2 to 0.5. After the second acid leaching of the metal-based raw material using the mixed leachate as the second leach solution, the pH of the resulting second leachate forming the metal-containing aqueous solution according to this aspect due to consumption of free acid by ions present in the metal-based raw material, such as hydroxide ions, may be 1.2 to 1.5.

[0130] More preferably, according to this aspect of the method of the present disclosure, the concentration of the resulting second leachate forming the metal-containing aqueous solution may be between 1.1 and 1.6, more preferably between 1.2 and 1.4 g / mL.

[0131] Thus, this aspect of the disclosed method using a mixed leach solution for the acid leaching of the separated undissolved fraction and the acid leaching of the raw metal-based material has the advantage that the pH of the resulting metal-containing aqueous solution can be increased without the addition of additional base or basic compounds compared to the case where only the lithium-containing raw material is leached (i.e., no second acid leaching of the raw metal-based material is performed), and at the same time, the leaching yield of the desired cathode active metals such as Ni, Co and / or Mn can be increased and their contents can be selectively increased as required, while the concentration of impurities such as Cu, Mg or Na in the resulting aqueous solution can be reduced by leaching the raw metal-based material and the separated undissolved fraction.

[0132] More advantageously, this aspect of the disclosed method allows for control of the leaching yield from the raw metal-based raw material by adding less reducing agent and acidic leaching reagent, completely avoiding leaching of impurities from the leaching of the raw metal-based raw material, and reducing chemical consumption. In addition, leaching of the raw metal-based raw material allows for control of the ratio of desired cathode active metals, such as Ni, Co and / or Mn, in the resulting leachate (i.e., metal-containing aqueous solution) and compensates for the variation of these metals due to the nature and composition of the lithium-containing raw material.

[0133] Furthermore, this aspect of the method according to the present disclosure can reduce the content of metals in the final separated undissolved fraction to produce high purity graphite, silicon or silicon-based materials of a quality that can be utilized in upcycling processes in the manufacture of anode materials with minimal pre-treatment steps, for example.

[0134] According to the fourth aspect described above, the present disclosure provides in a particularly preferred aspect a method for producing an aqueous metal-containing solution, comprising the steps of: - subjecting the lithium-containing feedstock to a first acid leach using a first aqueous leach solution comprising an acid leach reagent and a reducing agent to obtain a first leach solution; - filtering the first leachate from the first acid leach to separate the undissolved fraction; - subjecting the separated undissolved fraction to acid leaching using an aqueous leaching solution containing an acid leaching reagent and a reducing agent to obtain a leachate; - mixing the first leachate from the first acid leachate with the leachate from the acid leachate of the separated undissolved fraction to obtain a mixed leachate; and - subjecting the raw metallic material to a second acid leaching using the second aqueous leaching solution to obtain a second leachate. and using the mixed leachate as a second aqueous leach solution for a second acid leach, the resulting second leachate forming an aqueous metal-containing solution.

[0135] The preferred leaching conditions previously described also apply to this particularly preferred method.

[0136] In a particularly preferred embodiment of the present disclosure, the acidic leach reagent used in each of the leach solutions for the first, second and optional third acid leaches defined herein is sulphuric acid and the metal-containing aqueous solution formed is an aqueous metal sulphate-containing solution comprising at least lithium sulphate and more preferably one or more of nickel sulphate, cobalt sulphate and manganese sulphate.

[0137] Without further elaboration, it is believed that one skilled in the art can utilize the present invention to its fullest extent using this specification, including the drawings. Although the present invention has been described in this specification with respect to preferred embodiments thereof which represent the best mode contemplated for carrying out the invention, it will be understood that various modifications apparent to those skilled in the art can be made without departing from the scope of the present disclosure as set forth in the claims.

[0138] Preferred embodiments of the present invention will be described in more detail by means of examples and comparative examples, which are, however, presented herein for illustrative purposes only. EXAMPLES

[0139] Black mass used in the examples The black mass used in the following examples contained positive and negative electrode materials from NMC / graphite-based Li-ion batteries and was obtained by mechanical processing of these lithium-ion batteries. The composition of the black mass was as shown in Table 1a (dry basis; moisture <1%).

[0140] [Table 1a]

[0141] MHP used in the examples A commercially available nickel-rich MHP of the composition shown in Table 1b below was used in the following examples (dry basis).

[0142] [Table 1b]

[0143] Comparative Example 1: Leaching of black trout A 1 L laboratory reactor was used for leaching of black mass. The temperature was maintained at 40 °C with a hot plate. 126 g of H2SO4, corresponding to a 20% wt. excess over the stoichiometric amount required to leach black mass, was added to 356 g of water and mixed. 100 g of black mass was added to the solution and mixed for 1 h. Then, 28 g of H2O2 was added to the mixture and the slurry was mixed for another 2 h. The slurry was then filtered through a Büchner filter and the solid residue, consisting mainly of graphite, was washed with at least 3 times the mass of the solid residue with water. All the graphite was removed by filtration along with the solid residue. 42.3 g (dry weight) of solid was obtained. The pH of the filtrate was 0.2-0.4.

[0144] The composition of the graphite / solid residue after washing and drying, in terms of the amount of residual metals, expressed as wt % on a dry basis, was as shown in Table 2.

[0145] [Table 2]

[0146] Leaching yield is usually defined to better understand the efficiency of the process. It is defined as the weight percentage of each specific metal extracted from the black mass into the liquid solution. This leaching yield can be defined by the difference between the total initial mass of a metal in the black mass and the amount of this metal remaining in the graphite / solid residue. Thus, the leaching yield for black mass can be calculated by the following Equation 1:

[0147]

number

[0148] In the formula, the metal in the graphite ("Metal グラファイト ") and metals in black mass ("Metal ブラックマス ") is calculated from the concentration and weight of each material according to Equation 2 and Equation 3 below.

[0149]

number

[0150] The leaching yields of Ni, Co, Mn, Li, Al and Cu obtained with this method of leaching black mass are given in Table 3a below.

[0151] [Table 3a]

[0152] Example 1. Leaching of BM+MHP (parallel configuration according to FIG. 1) Black trout infusion Leaching of black mass was carried out in a 1 L laboratory reactor by the same method and conditions as in Comparative Example 1. After filtering off all the graphite together with the solid residue, 42.3 g (dry weight) of solid was obtained, and the pH of the filtrate was 0.2-0.4.

[0153] As a result, the composition of the graphite / solid residue after washing and drying, in terms of the amount of residual metals, was the same as that shown in Table 2 above, and the leaching yields of Ni, Co, Mn, Li, Al and Cu obtained with this method of leaching black mass were the same as those shown in Table 3a above.

[0154] Leaching of MHP A separate 1 L laboratory reactor was used for leaching of MHP. The temperature was maintained at 40 °C with a hot plate. 46 g of H2SO4, corresponding to 0% by weight excess over the stoichiometric amount required to leach MHP, was added to 356 g of water and mixed. 100 g of MHP was added to the solution and mixed for 1 h. 2.8 g of H2O2 was then added to the mixture and the slurry was mixed for an additional 2 h. The slurry was then filtered through a Büchner filter, but no solid residue was obtained. The pH of the filtrate was 1.3-1.5.

[0155] As no solids were obtained (i.e. the mass of Ni, Co and Mn in the solid residue was estimated to be 0 g), the leaching yields of Ni, Co and Mn obtained with this method of leaching MHP are as shown in Table 3b below.

[0156] [Table 3b]

[0157] Filtrate Mixing 500 g of filtrate from black mass leaching was mixed with 500 g of filtrate from MHP leaching in a 1 / 1 mass ratio in a 2 L laboratory reactor. The temperature was maintained at 40 °C using a hot plate and the solution was mixed for 3 h. The mixture was then filtered through a Büchner filter, but no solids were obtained. The pH of the resulting final solution was 0.7-0.9.

[0158] comparison The method according to Comparative Example 1 and the method according to Example 1 allow the leaching of lithium-containing raw material (black mass) with yields of more than 90% for Ni, Co, Mn and Li, with the Ni, Co, Mn and Li contents of the graphite residue being less than 4% by weight. The method according to Example 1 additionally allows the leaching of 100% of Ni, Co and Mn in the leaching of MHP. The leaching of MHP in the method according to Example 1, which is carried out in a parallel configuration to the leaching of black mass according to this aspect of the disclosure, advantageously allows the obtaining after mixing of a final treatment solution enriched in Ni, Co and Mn and with an elevated pH such that its properties are suitable for further processing and recovery of Ni, Co, Mn and Li in subsequent impurity removal and recovery processes.

[0159] Example 2. Leaching of BM+MHP (series configuration according to FIG. 2) Black trout infusion A 1 L laboratory reactor was used for leaching of black mass. The temperature was maintained at 40 °C with a hot plate. 170 g of H2SO4, corresponding to a 61.9 wt% excess over the stoichiometric amount required to leach black mass, was added to 356 g of water and mixed. 100 g of black mass was added to the solution and mixed for 1 h. After 1 h, 28 g of H2O2 was added to the mixture and the slurry was mixed for another 2 h. The slurry was then filtered through a Büchner filter and the solid residue, consisting mainly of graphite, was washed with at least 3 times the mass of the solid residue with water. All the graphite is removed by filtration together with the solid residue. 40.3 g (dry weight) of solid was obtained. The pH of the filtrate was 0.1-0.3.

[0160] The composition of the graphite / solid residue after washing and drying, in terms of the amount of residual metals, expressed as wt % on a dry basis, was as shown in Table 4.

[0161] [Table 4]

[0162] The leaching yields of Ni, Co, Mn, Li, Al and Cu obtained with this method of leaching black mass, calculated according to equations 1 to 3 above, are given in Table 5 below.

[0163] [Table 5]

[0164] Leaching of MHP The filtrate from black mass leaching was placed in another 1 L laboratory reactor. The temperature was maintained at 40 °C with a hot plate. 520 g water was added to maintain the solid to liquid mass ratio (S / L) at 0.1-0.2. 100 g MHP was added to the solution and mixed for 1 h. After 1 h, 3 g H2O2 was added to the mixture and the slurry was mixed for another 2 h. The mixture was then filtered through a Buchner filter but no solids were obtained. 100 wt% of Ni, Co and Mn were leached. The final pH of the resulting solution was 1.4-1.6.

[0165] comparison Compared to the methods according to Comparative Example 1 and Example 1, the leaching of MHP in a second leaching stage carried out in series with the leaching of black mass according to this aspect of the disclosure allows the addition of more H2SO4 to the first stage leaching (leaching of black mass), e.g. the amount of H2SO4 required to leach MHP in addition to the excess H2SO4 added for the leaching of black mass, resulting in a corresponding increase in the excess H2SO4 in the filtrate obtained in the first stage leaching of black mass. Thus, compared to the black mass leaching carried out according to Comparative Example 1 and Example 1, a significant improvement in the metal extraction rate is observed, as indicated by the lower concentration of metals in the graphite (see Tables 2 and 4), so that a higher leaching yield of Ni, Co, Mn and Li of more than 99% in the black mass and the recovery of graphite with reduced impurities of Ni, Co, Mn and Li of less than 0.3% by weight (higher quality graphite) can be achieved by the method of Example 2. Furthermore, the subsequent leaching of MHP in the second leaching stage ensures that a greater amount of excess acid remaining unreacted in the black mass leaching is consumed by MHP, thereby advantageously increasing the pH of the final treated solution to a greater extent, allowing the pH of the solution to be adjusted to a pH suitable for further processing, and further ensuring that the final treated solution is enriched in Ni, Co and Mn, the properties of which are suitable for further processing and recovery of Ni, Co, Mn and Li in the subsequent impurity removal and recovery process.

[0166] Example 3. Leaching of BM+Graphite+MHP (series configuration according to FIG. 3) Black trout infusion The leaching of black mass was carried out in the same manner and under the same conditions as in Comparative Example 1 or Example 1. After filtering off all the graphite together with the solid residue, 42.3 g (dry weight) of solid was obtained, and the pH of the filtrate was 0.2-0.4.

[0167] The purity of the resulting graphite / solid residue and leaching yields were the same as those shown in Tables 2 and 3a above.

[0168] Graphite Leaching A 1 L laboratory reactor was used for leaching of graphite. The temperature was maintained at 40 °C with a hot plate. 46 g of H2SO4, corresponding to 0% by weight excess over the stoichiometric amount required to leach MHP, was added to 356 g of water and mixed. 43.2 g of residual graphite from the black mass leaching was added to the solution and mixed for 1 h. After 1 h, 2.8 g of H2O2 was added to the mixture and the slurry was mixed for another 2 h. The slurry was then filtered through a Büchner filter and the residual graphite was washed with at least 3 times the mass of the residual graphite with water. 40.2 g of graphite (dry weight) was obtained. The pH of the filtrate was 0.1-0.3.

[0169] After washing and drying, the composition of the graphite, in terms of the amount of residual metals, in weight percent on a dry basis, was as shown below in Table 6.

[0170] [Table 6]

[0171] The leaching yields of Ni, Co, Mn, Li, Al and Cu obtained by this method of leaching black mass and graphite, calculated according to equations 1 to 3 above, are given in Table 7 below.

[0172] [Table 7]

[0173] MHP leaching and filtrate mixing 500 g of the filtrate from the graphite leaching was placed in another 1 L laboratory reactor. The temperature was maintained at 40°C with a hot plate. 100 g of MHP was added to the solution and mixed for 3 hours. After this 3 hour period, the mixture was filtered through a Buchner filter but no solids were obtained. 100 wt% of Ni, Co and Mn were leached. The final pH of the resulting solution was 1.4-1.6. 500 g of this filtrate was mixed with 500 g of the filtrate from the black mass leaching and mixed at 40°C for 1 hour. The mixture was then filtered through a Buchner filter but no solids were obtained. The final pH of the resulting solution was 0.8-1.0.

[0174] Example 4. Leaching of BM+Graphite+MHP (series configuration according to FIG. 4) Black trout infusion The leaching of the black mass was carried out in the same manner and under the same conditions as previously described for Comparative Example 1 or Example 1. After filtering off all the graphite together with the solid residue, 42.3 g (dry weight) of solid was obtained, the pH of the filtrate was 0.2-0.4.

[0175] The purity of the resulting graphite / solid residue and leaching yields were the same as those shown in Tables 2 and 3a above.

[0176] Graphite Leaching Graphite leaching was performed in the same manner and under the same conditions as in Example 3. 40.2 g (dry weight) of graphite was obtained. The pH of the filtrate was 0.1-0.3. The purity and leaching yield of the obtained graphite were the same as those shown in Tables 6 and 7 above.

[0177] Blending of filtrates and leaching of MHP 500 g of the filtrate from black mass leaching was mixed with 500 g of the filtrate from graphite leaching in a 1 / 1 mass ratio in a 2 L laboratory reactor. The temperature was maintained at 40°C with a hot plate and the solution was mixed for 1 hour. 100 g of MHP was then added to the solution and mixed for 3 hours. After this 3 hour period, the mixture was filtered through a Buchner filter but no solids were obtained. 100 wt% of Ni, Co and Mn were leached. The final pH of the resulting solution was 1.2-1.4.

[0178] comparison Due to the graphite leaching step, the method according to the embodiment of the present disclosure described in Examples 3 and 4 allows for an overall more significant improvement in metal extraction rates as shown by the lower concentration of metals in the graphite (see Table 6), resulting in higher Ni, Co, Mn and Li leaching yields of over 99.9% (see Table 7) and recovery of graphite with even fewer impurities (higher quality graphite). Furthermore, the subsequent leaching of the MHP ensures that the excess H2SO4 remaining unreacted in the leaching of the black mass and / or graphite is consumed by the MHP, thereby advantageously increasing the pH of the final treated solution, allowing the pH of the solution to be adjusted to a pH suitable for further processing, further ensuring that the final treated solution is enriched in Ni, Co and Mn, properties suitable for further processing and recovery of Ni, Co, Mn and Li in the subsequent impurity removal and recovery processes.

Claims

1. A method for producing a metal-containing aqueous solution, In order to form the aforementioned metal-containing aqueous solution, - To perform a first acid leaching on a lithium-containing raw material using a first leaching solution to obtain a first leachate; and - A second acid leaching is performed on a metal-based material raw material using a second leaching solution to obtain a second leaching solution. Methods that include...

2. The method according to claim 1, wherein the lithium-containing raw material comprises one or more of Ni, Co, and Mn, and / or the metal-based material raw material comprises one or more of Ni, Co, and Mn.

3. The method according to claim 1, wherein the first leaching solution for the first acid leaching comprises a reducing agent, and / or the second leaching solution for the second acid leaching comprises a reducing agent, wherein the reducing agent is preferably selected from hydrogen peroxide, hydrazine and its salts, methanol, ethanol, sugar, ascorbic acid, urea, starch, cellulose, and combinations thereof.

4. The method according to claim 1, wherein the total concentration of the target metal in the first leaching solution is controlled by adding water during the first acid leaching so that it is in a range sufficiently lower than the solubility of each metal, preferably 80 g / L to 120 g / L, and / or the total concentration of the target metal in the second leaching solution is controlled by adding water during the second acid leaching so that it is in a range sufficiently lower than the solubility of each metal, preferably 80 g / L to 120 g / L.

5. The method according to claim 1, further comprising mixing a first leachate obtained by the first acid leaching with a second leachate obtained by the second acid leaching to form the metal-containing aqueous solution.

6. The method according to claim 1, wherein the first leaching solution contains an amount of acidic leaching reagent in an excess of 5% by weight or more compared to the stoichiometric amount, and / or the second leaching reagent contains an amount of acidic leaching reagent in an excess of 0% to 10% by weight compared to the stoichiometric amount.

7. The method according to claim 1, wherein the first leaching solution contains 2% to 7% by volume of a reducing agent based on its total volume, and / or the second leaching solution contains 0.1% to 3% by volume of a reducing agent based on its total volume.

8. The method according to claim 1, wherein the first leachate obtained in the first acid leaching is used as a second leaching solution for the second acid leaching, and the resulting second leachate forms the metal-containing aqueous solution.

9. The method according to claim 8, wherein the first leaching solution contains an amount of acidic leaching reagent in an excess of 20% by weight or more compared to the stoichiometric amount.

10. The method according to claim 1, further comprising filtering the first leachate obtained by the first acid leaching to separate the undissolved fraction.

11. The method according to claim 10, further comprising performing acid leaching on the separated undissolved fraction to obtain an leachate, wherein the leaching solution for acid leaching of the separated undissolved fraction comprises an acid leaching reagent and a reducing agent.

12. The leachate obtained by acid leaching of the separated undissolved fraction is used as the second leaching solution for the second acid leaching; The method according to claim 11, further comprising mixing the second leachate produced by the second acid leaching with the first leachate obtained by the first acid leaching to form the metal-containing aqueous solution.

13. The method further includes mixing the first leachate obtained by the first acid leaching with the leachate obtained by the acid leaching of the separated undissolved fraction to obtain a mixed leachate. The method according to claim 11 or 12, wherein the mixed leachate is used as a second leaching solution for the second acid leaching, and the resulting second leaching solution forms the metal-containing aqueous solution.

14. The method according to claim 1, wherein the lithium-containing raw material is selected from recycled material raw materials, preferably from crushed lithium-ion batteries or lithium-ion battery manufacturing scrap, or a combination thereof, and / or the metallic material raw material is selected from metal-containing concentrate, mixed hydroxide precipitate (MHP), mixed sulfide precipitate (MSP), matte, nickel laterite, or ferronickel, or a combination thereof.

15. The method according to claim 1, wherein the metal in the metal-containing aqueous solution comprises one or more of Li, Ni, Co, and Mn, preferably two or more of Li, Ni, Co, and Mn, and more preferably Li, Ni, Co, and Mn.

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