Process for the recovery of valuable metals

Abstract

The application provides a valuable metal recovery method, which comprises the following steps: a leaching process, in which a metal-containing recovery material is contacted with an acid solution, so that the metal in the recovery material is leached into the acid solution to obtain an acid leaching solution; a removal process, in which the acid leaching solution is removed by using a first solvent to obtain a removed solution containing valuable metals, wherein the valuable metals include a first valuable metal element and a second valuable metal element, the first valuable metal element includes at least one of nickel, cobalt and manganese, and the second valuable metal element includes lithium; and an extraction process, in which the removed solution is extracted by using a second solvent to obtain an extraction solution containing the first valuable metal element and a raffinate containing the second valuable metal element, wherein the second solvent includes a pyridine-based extractant and a phosphate-based extractant. The recovery method can not only reduce the recovery cost of valuable metals, but also improve the recovery rate and utilization value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource recycling, in particular to a valuable metal recycling method. BACKGROUND

[0002] Valuable metals generally refer to metals with utilization value in raw materials for refining metals, such as nickel (Ni), cobalt (Co), manganese (Mn) and lithium (Li) metals, which can be utilized in various industrial fields such as automobiles and electrical equipment.

[0003] However, in the related art, the recycling cost of valuable metals is high, and the recycling rate and utilization value of valuable metals are low. SUMMARY

[0004] The present application provides a valuable metal recycling method which not only reduces the recycling cost of valuable metals, but also improves the recycling rate and utilization value.

[0005] The present application provides a valuable metal recycling method, which comprises:

[0006] An immersion process, in which a metal-containing recyclate is contacted with an acid solution to leach the metal in the recyclate into the acid solution, to obtain an acid leaching solution;

[0007] A purification process, in which the acid leaching solution is purified using a first solvent to obtain a purified solution containing valuable metals, wherein the valuable metals include a first valuable metal element and a second valuable metal element, the first valuable metal element includes at least one of nickel, cobalt and manganese, and the second valuable metal element includes lithium;

[0008] An extraction process, in which the purified solution is extracted using a second solvent to obtain an extraction solution containing the first valuable metal element and a raffinate containing the second valuable metal element, wherein the second solvent includes a pyridine-based extractant and a phosphate-based extractant.

[0009] In the recycling method provided by the present application, the pyridine-based extractant in the second solvent has a very high affinity for nickel, cobalt and manganese, the hydrocarbon functional group of the phosphate-based extractant in the second solvent can further enhance the extraction effect of cobalt and manganese metals, and the pyridine-based extractant has low affinity for impurity metals, which can inhibit the extraction effect of the phosphate-based extractant on other metals (such as Ca, Mg, Cu, Zn and other impurity metals) in the mixed system, so that the first valuable metal element and the second valuable metal element in the purified solution can be separated, i.e. the first valuable metal element in the purified solution is extracted to obtain an extraction solution containing the first valuable metal element, while the second valuable metal element is leached and retained in the raffinate, thereby improving the recycling rate of the first valuable metal element and the second valuable metal element.

[0010] Specifically, in the recycling method provided by the embodiments of the present application, through the leaching process, the metals in the recycled material can be leached into the acid leaching solution to improve the recovery rate of the valuable metals, through the impurity removal process, the impurity metals other than nickel, cobalt, manganese and lithium can be removed to reduce the content of impurity metals in the solution obtained in the subsequent extraction, through the extraction process, the second solvent including the pyridine-based extractant and the phosphate ester-based extractant is used to treat the impurity-removed solution, which can effectively separate the first valuable metal element from the second valuable metal element, that is, the extraction solution containing the first valuable metal element and the raffinate solution containing the second valuable metal element are obtained, so that the first valuable metal element and the second valuable metal element in the recycled material can be recycled synchronously, the process flow of recycling the valuable metals from the recycled material is simplified, the recovery rate of the valuable metals is improved, and the effective separation of the first valuable metal element and the second valuable metal element can also be used in battery manufacturing, so that their utilization value is improved. Further, the recycling method provided by the present application simplifies the process flow of recycling the valuable metals, which not only can reduce the loss of valuable metals in the recycling process, but also can reduce the water swelling in the recycling of lithium, reduce the evaporation water amount of the lithium solution in the subsequent lithium recovery, and reduce the comprehensive cost of recycling lithium, thereby helping to reduce the demand for recycling equipment and the floor area of the recycling plant, and further helping to reduce the recycling cost of the valuable metals in the recycled material. In addition, in the above processes, less pollutants are generated, so that the recycling method of the valuable metals is environmentally friendly. Therefore, the recycling method provided by the embodiments of the present application has the advantages of simplified process flow, low recycling cost, high recovery rate of valuable metals, high utilization value, and less pollutants, and is environmentally friendly.

[0011] In some embodiments of the present application, the extraction process comprises:

[0012] In the saponification step, the second solvent and the diluent are mixed for saponification to obtain a saponified extractant.

[0013] In the extraction step, the saponified extractant is used to extract the impurity-removed solution to obtain an extraction solution containing the first valuable metal element.

[0014] In some embodiments of the present application, in the saponification step, the mass ratio of the second solvent to the diluent is 1:(1-4).

[0015] In some embodiments of the present application, the saponification rate of saponification is 20%-80%.

[0016] In some embodiments of the present application, the volume ratio of the saponified extractant to the impurity-removed solution is (4-10):1.

[0017] In some embodiments of the present application, the pH of the impurity-removed solution is 3-5, and the extraction temperature is 30°C-60°C.

[0018] In some embodiments of the present application, in the extraction process, the pyridine-based extractant comprises pyridine or a pyridine-based derivative.

[0019] In some embodiments of the present application, the pyridine-based extractant comprises one or more of pyridine carboxylate and pyridine-based phosphoramide.

[0020] In some embodiments of the present application, the phosphate-based extractant comprises one or more of diisooctyl phosphate, 2-ethylhexyl 2-ethylhexyl phosphate, tributyl phosphate, 2,4,4-trimethylpentyl diphosphonic acid.

[0021] In some embodiments of the present application, in the extraction process, the volume ratio of the pyridine-based extractant and the phosphate-based extractant is (1-100):(1-100).

[0022] In some embodiments of the present application, the first solvent comprises a basic substance and a decontamination extractant, and the decontamination process comprises:

[0023] The first decontamination step is to adjust the pH of the acid leaching solution to 3-5 using a basic substance to precipitate iron and aluminum in the acid leaching solution, and solid-liquid separation to obtain a post-iron and aluminum removal solution;

[0024] The second decontamination step is to use a decontamination extractant to extract and decontaminate the post-iron and aluminum removal solution to obtain a post-decontamination solution containing valuable metals.

[0025] In some embodiments of the present application, in the second decontamination step, the volume ratio of the decontamination extractant and the post-iron and aluminum removal solution is 1:(0.8-3).

[0026] In some embodiments of the present application, the decontamination extractant comprises a phosphoric acid-based extractant and / or a phosphonic acid-based extractant.

[0027] In some embodiments of the present application, the decontamination extractant comprises one or more of P204, P507, and C272.

[0028] In some embodiments of the present application, the pH of the post-iron and aluminum removal solution is 2-6.

[0029] In some embodiments of the present application, the recovery method further comprises:

[0030] The stripping process is to strip the extraction solution to obtain a stripping solution;

[0031] The oil removal process is to remove oil from the stripping solution.

[0032] In some embodiments of the present application, the stripping process comprises:

[0033] The washing step is to wash the extraction solution using a first acid solution to obtain a post-washing solution;

[0034] The stripping step uses a second acid solution to strip the washed solution to obtain a first valuable metal element-containing stripping solution.

[0035] In some embodiments of the present application, the first acid solution comprises sulfuric acid and / or hydrochloric acid.

[0036] In some embodiments of the present application, the acidity of the first acid solution is 0.1-1.5 mol / L.

[0037] In some embodiments of the present application, the second acid solution comprises sulfuric acid and / or hydrochloric acid.

[0038] In some embodiments of the present application, the acidity of the second acid solution is 1.5-3 mol / L.

[0039] In some embodiments of the present application, the recyclates comprise battery recyclates. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0041] Figure 1 The flowchart of the valuable metal recovery method provided by some embodiments of the present application;

[0042] Figure 2 The flowchart of the valuable metal recovery method provided by some embodiments of the present application;

[0043] Figure 3 The flowchart of the valuable metal recovery method provided by some embodiments of the present application;

[0044] Figure 4 The flowchart of the valuable metal recovery method provided by some embodiments of the present application;

[0045] Figure 5 The flowchart of the valuable metal recovery method provided by some embodiments of the present application;

[0046] Figure 6 The flowchart of the valuable metal recovery method provided by some embodiments of the present application. DETAILED DESCRIPTION

[0047] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0049] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0050] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0051] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0052] If not specifically stated, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following satisfy the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0053] In this application, the recyclates include battery recyclates. The battery recyclates refer to a mixture containing main components of batteries such as cathodes, which are obtained by recycling batteries, wherein the batteries can be nickel-sulfur secondary batteries, nickel-hydrogen secondary batteries, lithium-ion secondary batteries, etc. In some examples, the cathode in the lithium-ion secondary battery contains a cathode current collector, which can be a metal foil of aluminum, copper, nickel, etc., and a cathode active material, which can include valuable metals such as nickel (Ni), cobalt (Co), manganese (Mn), and lithium (Li). In some specific examples, the battery recyclates can be a mixture containing valuable metals such as Ni, Co, Mn, and Li and carbon powder obtained by processes such as disassembly, crushing, screening, pyrolysis, sorting, etc., which can also be referred to as battery black powder. Further, in some examples, the mass percentage of each component in the battery recyclates is: Ni 15%-25%, Co 2%-12%, Mn 6%-15%, Fe 0.5%-3%, Mg 0.01%-0.5%, Si 0.01%-0.5%, Zn 0.001%-0.05%, S 0.1%-1%, Cu 0.5%-3%, Al 1%-12%, and Li 3%-6%.

[0054] In this application, battery-grade nickel-cobalt-manganese sulfate refers to a nickel sulfate solution that meets the national standard GB / T 26524-2011, a cobalt sulfate solution that meets the industry standard HG / T 5918-2021, and a manganese sulfate solution that meets the industry standard HG / T 4823-2015.

[0055] In this application, battery-grade lithium carbonate refers to the industry standard YS / T 582-2013 for nickel carbonate solution.

[0056] Please refer to Figure 1 As shown in the drawings, the present application provides a valuable metal recovery method, which comprises:

[0057] S100, a leaching process, in which the metal-containing recyclates are contacted with an acid solution to leach the metals in the recyclates into the acid solution, to obtain an acid leaching solution;

[0058] S200, a removing impurity process, removing impurities from the acid leaching solution by using a first solvent to obtain a post-removing impurity solution containing valuable metals, wherein the valuable metals include first valuable metal elements and second valuable metal elements, the first valuable metal elements include at least one of nickel, cobalt and manganese, and the second valuable metal elements include lithium;

[0059] S300, an extraction process, extracting the post-removing impurity solution by using a second solvent to obtain an extraction solution containing the first valuable metal elements and a raffinate solution containing the second valuable metal elements, wherein the second solvent includes a pyridine-based extractant and a phosphate-based extractant.

[0060] In the recycling method provided by the embodiments of the present application, the pyridine-based extractant in the second solvent has a very high affinity for nickel, cobalt and manganese, the phosphate-based extractant in the second solvent can further enhance the extraction effect of cobalt and manganese metals, and the pyridine-based extractant has a low affinity for impurity metals. Thus, through the synergistic effect of the phosphate-based extractant and the pyridine-based extractant in the second solvent, the first valuable metal elements and the second valuable metal elements in the post-removing impurity solution can be effectively separated, that is, the first valuable metal elements in the post-removing impurity solution are extracted to obtain the extraction solution, and the second valuable leaching is retained in the raffinate solution, thereby improving the recovery rate of the first valuable metal elements and the second valuable metal elements.

[0061] Specifically, in the recycling method provided by the embodiments of the present application, the metals in the recyclables can be leached into the acid leaching solution through the leaching process to improve the recovery rate of the valuable metals, the impurity metals other than nickel, cobalt, manganese and lithium can be removed through the removing impurity process to reduce the content of impurity metals in the solution obtained by subsequent extraction, and the first valuable metal elements and the second valuable metal elements can be effectively separated through the extraction process by using the second solvent including the pyridine-based extractant and the phosphate-based extractant to treat the post-removing impurity solution, that is, the extraction solution containing the first valuable metal elements and the raffinate solution containing the second valuable metal elements are obtained. Thus, the first valuable metal elements and the second valuable metal elements in the recyclables can be recovered synchronously, the process flow of recycling the valuable metals from the recyclables is simplified, the recovery rate of the valuable metals is improved, and the effective separation of the first valuable metal elements and the second valuable metal elements can also be used in battery manufacturing, so that their utilization value is improved.

[0062] Further, the recovery method provided by the application simplifies the process flow of valuable metal recovery, which can not only reduce the loss of valuable metals in the recovery process, but also reduce the water swelling in the lithium recovery process, reduce the evaporation water amount of the lithium liquid in the back end, reduce the comprehensive cost of lithium, and further help to reduce the demand for recovery equipment and the floor area of the recovery plant, and further reduce the recovery cost of valuable metals in the recovered material. In addition, in the above processes, the pollutants generated are less, and the valuable metal recovery method is environmentally friendly. Therefore, the recovery method provided by the embodiment of the application has the advantages of simplified process flow, low recovery cost, high recovery rate of valuable metals, high utilization value, and less pollutants, and is environmentally friendly.

[0063] Please refer to Figure 2 In the embodiment of the application, the extraction process includes:

[0064] S310, a saponification step, mixing the second solvent and the diluent for saponification to obtain a saponified extractant;

[0065] S320, an extraction step, using the saponified extractant to extract the impurity-removed liquid to obtain an extraction liquid containing the first valuable metal element.

[0066] In the embodiment, mixing the second solvent and the diluent and saponifying can help to reduce the density and viscosity of the second solvent, improve the phase separation performance of the second solvent and the impurity-removed liquid, reduce the loss of the second solvent, and adjust the concentration of the second solvent, so as to achieve a relatively ideal extraction rate and extraction selectivity. In some embodiments of the application, the diluent can be sulfonated kerosene (260# solvent oil).

[0067] In the embodiment of the application, in the saponification step S310, the mass ratio of the second solvent to the diluent is 1:(1-4). When the ratio of the second solvent to the diluent is in the above range, it can help to improve the extraction effect of the second solvent, so as to improve the recovery rate of the first valuable metal element. The diluent can be one or more of sodium hydroxide solution or ammonia water. In some embodiments, the mass ratio of the second solvent to the diluent can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4, etc.

[0068] A suitable saponification rate can help to improve the extraction effect of the second solvent on the first valuable metal element. In some embodiments of the application, the saponification rate of the saponification treatment can be controlled to be 20%-80%. In some embodiments, the saponification rate can be 20%, 30%, 40%, 50%, 60%, 70%, 80%, or a value range composed of any two of the above values, for example, 30%-80%, 40%-70%.

[0069] In some embodiments, the volume ratio of the saponification extractant and the impurity-removed solution is (4-18): 1. When the volume ratio of the saponification extractant and the impurity-removed solution is within the above range, the first valuable metal element and the second valuable metal element can be efficiently separated, thereby helping to improve the recovery rate of the first valuable metal element. In some embodiments, the volume ratio of the saponification extractant and the impurity-removed solution can be 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, or 10: 1, etc.

[0070] In addition, the parameters of the extraction process within a suitable range can help to improve the extraction effect of the second solvent, and further efficiently separate the first valuable metal element and the second valuable metal element. In some embodiments, the pH of the impurity-removed solution is 3-5. For example, the pH of the impurity-removed solution can be 3, 3.5, 4, 4.5, or 5, etc. The temperature of the impurity-removed solution can be maintained at 30-60°C. For example, the temperature of the impurity-removed solution can be 30°C, 40°C, 50°C, or 60°C, etc.

[0071] In addition, the parameters of the extraction process within a suitable range can help to improve the extraction effect of the second solvent, and further efficiently separate the first valuable metal element and the second valuable metal element. In some embodiments, the pH of the impurity-removed solution is 3-5. For example, the pH of the impurity-removed solution can be 3, 3.5, 4, 4.5, or 5, etc. The temperature of the impurity-removed solution can be maintained at 30-60°C. For example, the temperature of the impurity-removed solution can be 30°C, 40°C, 50°C, or 60°C, etc.

[0072] In the embodiments of the present application, in the extraction process S300, the pyridine-based extractant includes pyridine or a pyridine-based derivative. The pyridine-based extractant includes one or more of pyridine carboxylate and pyridine-based phosphoramide; the phosphate ester-based extractant includes one or more of diisooctyl phosphate, 2-ethylhexyl phosphate 2-ethylhexyl ester, tributyl phosphate, and 2,4,4-trimethylpentyl diphosphonic acid. These extractants have high cost performance, and commercially available models can be used, thereby helping to extract the first valuable metal element from the impurity-removed solution while reducing the recovery cost of the first valuable metal element. It should be understood that the plurality in the present application includes two and more than three. Therefore, the combination of the second solvent in the present embodiment can include the following combinations: one of the pyridine-based extractant and one of the phosphate ester-based extractant, one of the pyridine-based extractant and multiple of the phosphate ester-based extractant, multiple of the pyridine-based extractant and one of the phosphate ester-based extractant, and multiple of the pyridine-based extractant and multiple of the phosphate ester-based extractant.

[0073] In addition, the volume ratio of the pyridine extractant to the phosphate ester extractant in a proper range can also help to improve the recovery rate of the first valuable metal element. In some embodiments, the volume ratio of the pyridine extractant to the phosphate ester extractant is (1-100):(1-100), which can be 95:5, 9:1, 8:2, 7:3, or 6:4, etc. When the volume ratio of the pyridine extractant to the phosphate ester extractant is in the above proper range, both the recovery rate of the first valuable metal element and the utilization rate of the pyridine extractant and the phosphate ester extractant can be improved.

[0074] Referring to Figure 3 In the embodiments of the present application, the first solvent in S200 includes a basic substance and a decontamination extractant, and the decontamination process includes:

[0075] S210, a first decontamination step, the pH of the acid leaching solution is adjusted to 3-5 by using a basic substance to precipitate iron and aluminum in the acid leaching solution, and solid-liquid separation is performed to obtain a post-iron and aluminum removal solution.

[0076] S220, a second decontamination step, the post-iron and aluminum removal solution is extracted by using a decontamination extractant to obtain a post-decontamination solution containing valuable metals.

[0077] In the above embodiments, when the acid leaching solution contains iron and aluminum, the pH of the acid leaching solution is adjusted to 3 or more to remove the iron and aluminum therein, and the adjustment of the pH of the acid leaching solution to 3-5 also helps the decontamination extractant to function. The basic substance can include calcium carbonate, hydroxide, etc. The solid-liquid separation in the first decontamination step S210 can be any method for separating solids and liquids known in the art, for example, the solid-liquid separation process can be performed by centrifugal separation method, tilting method, filtration method, etc.

[0078] In the second decontamination step S200, the decontamination extractant can be selected from phosphoric acid extractant or phosphonic acid extractant to further remove impurity metals such as Zn, Al, Cu, Fe, Cd, Cr, Ca, Mg, etc., and the decontamination extractant is preferably one or more of P204, P507, C272.

[0079] In addition, the parameters of the post-iron and aluminum removal solution in a proper range can also help to improve the extraction effect of the decontamination extractant, further reduce the content of impurity metals in the post-decontamination solution, and retain valuable metals such as nickel, cobalt, manganese, and lithium in the post-decontamination solution. In some embodiments of the present application, the volume ratio of the decontamination extractant to the post-iron and aluminum removal solution is 1:(0.8-3), which can be 1:0.8, 1:1, 1:1.5, 1:2, or 1:3, etc.

[0080] In some embodiments of the present application, the pH of the post-iron and aluminum removal solution is maintained at 2-6. For example, the pH of the post-iron and aluminum removal solution can be 2, 3, 4, 5, or 6, etc.

[0081] In some embodiments of the present application, the temperature of the first impurity removal step can be maintained at 30-60°C. For example, the temperature of the first impurity removal step can be 30°C, 40°C, 50°C or 60°C, etc.

[0082] In addition, in order to further reduce the content of impurity metals such as Zn, Al, Cu, Fe, Cd, Cr, Ca, Mg, etc. in the impurity-removed solution, the extraction stages of the second impurity removal step can use multi-stage extraction according to the content of the extracted impurity metals and the degree of extraction required. In some embodiments, the extraction stages of the second impurity removal step can be 5-14 stages. For example, the extraction stages of the second impurity removal step can be 5 stages, 6 stages, 7 stages, 8 stages, 9 stages, 10 stages, 11 stages, 12 stages, 13 stages or 14 stages, etc.

[0083] Referring to Figure 4 In some embodiments of the present application, the recovery method can further include:

[0084] S400, a stripping process, stripping the extraction solution to obtain a stripping solution.

[0085] S500, an oil removal process, removing oil from the stripping solution.

[0086] In the present embodiment, in order to obtain a salt solution of the first valuable metal element of battery grade, the extraction solution needs to be further treated, i.e. the extraction solution is subjected to stripping and oil removal treatment. The stripping treatment can convert the first valuable metal element into its corresponding salt and transfer the first valuable metal element from the extraction solution to the stripping solution. Further, the oil removal treatment of the stripping solution can remove part of the diluent remaining in the stripping solution. In some embodiments, before the extraction solution is subjected to the stripping step, a washing step can be performed to further remove impurity metals from the extraction solution.

[0087] The acid solution used in the washing step and the stripping step can reduce the content of impurity metals and improve the recovery rate of the first valuable metal element within a suitable range. In some embodiments, the first acid solution used in the washing step can include sulfuric acid and / or hydrochloric acid, and the acidity of the first acid solution can be 0.1-1.5 mol / L. For example, the first acid solution can be sulfuric acid, and the acidity of the sulfuric acid can be 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L or 1.5 mol / L.

[0088] The second acid solution used in the stripping step can include sulfuric acid and / or hydrochloric acid, and the acidity of the second acid solution can be 1.5 mol / L-3 mol / L. Exemplarily, the second acid solution can be sulfuric acid, and the acidity of the sulfuric acid can be 1.5 mol / L, 1.7 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, or 3 mol / L.

[0089] Referring to Figure 5 As shown in the drawings, in some embodiments of the present application, the recovery method can further include:

[0090] S600, a lithium extraction process, after one or more of oil removal, impurity removal, and evaporation and lithium precipitation are sequentially performed on the raffinate, crude lithium carbonate is obtained, and after one or more of carbonization impurity removal, heating decomposition, and centrifugal drying are sequentially performed on the crude lithium carbonate, battery-grade lithium carbonate is obtained.

[0091] Referring to Figure 6 As shown in the drawings, in some embodiments of the present application, the recovery method can further include:

[0092] A first impurity removal step, using an alkaline substance to adjust the pH of the acid leaching solution of the recovered material to 3-5, to obtain a post-iron and aluminum removal solution.

[0093] A second impurity removal step, using one or more of P204, P507, and C272 to remove impurities from the post-iron and aluminum removal solution of the recovered material, to obtain a post-impurity removal solution.

[0094] In the second impurity removal step, the volume ratio of the impurity removal extractant to the post-iron and aluminum removal solution is 1:(0.8-3), the temperature of the post-iron and aluminum removal solution is maintained at 30°C-60°C, and the number of stages of impurity removal extraction is 5-14.

[0095] An extraction process, after a pyridine-based extractant (pyridine carboxylic acid ester, pyridyl-containing calixarene derivative, etc., acidic group compound, etc.) and a phosphoric acid ester-based extractant (diisooctyl phosphate, 2-ethylhexyl phosphate 2-ethylhexyl ester, tributyl phosphate, di(2,4,4-trimethylpentyl) phosphonic acid, etc.) are mixed in a volume ratio of (1-100):(1-100), and then mixed with a diluent in a volume ratio of 1:(1-4) and saponified to obtain a saponified extractant, the saponified extractant is used to extract the post-impurity removal solution to obtain an extract solution and a raffinate. The saponifying agent used for saponification is sodium soap or ammonia soap, the saponification rate is 20%-80%, the extraction temperature is 30°C-60°C, and the number of stages of extraction is 4-12.

[0096] A stripping process, after the extract solution is washed with dilute sulfuric acid with an acidity of 0.1 mol / L-1.5 mol / L, dilute sulfuric acid with an acidity of 1.5 mol / L-3 mol / L is used for stripping to obtain a stripped solution.

[0097] The oil removal process is performed on the stripping solution to obtain a solution of the first valuable metal element salt.

[0098] In addition, the recovery method provided by the present application further includes processing of the raffinate, i.e., a lithium extraction process, in which the raffinate is deoiled, impurities are removed, and then lithium is precipitated by evaporation to obtain crude lithium carbonate. The crude lithium carbonate is carbonized to remove impurities, heated and decomposed, and then centrifuged and dried to obtain battery-grade lithium carbonate.

[0099] It should be noted that the stripping process and the lithium extraction process have no sequence in the present application.

[0100] The following examples more specifically describe the disclosure of the present application, which are only used for illustrative purposes, because various modifications and changes within the scope of the disclosure of the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents and raw materials used in the examples are commercially available or synthesized according to conventional methods, and the instruments used in the examples are commercially available.

[0101] The components of the recovered material and its acid leaching solution used in the following examples are shown in the following table. It should be noted that the components of the recovered material used in the examples of the present application are only exemplary and should not be construed as limiting the idea of the present application, i.e., recovering valuable metals such as nickel, cobalt, manganese, and lithium from the recovered material.

[0102] Example 1

[0103] The present example provides a valuable metal recovery method, which includes the following steps:

[0104] The leaching process is performed on 200g of battery material containing nickel, cobalt, manganese, and lithium metals using concentrated sulfuric acid with a concentration of 98% to leach the metals into an acid solution, thereby obtaining an acid leaching solution. In the leaching process, the pH is maintained at about 1, the leaching temperature is 80°C, and the leaching reaction time is 6h.

[0105] The first impurity removal step is performed using calcium carbonate to adjust the pH of the acid leaching solution to 4.5 to remove iron and aluminum, thereby obtaining an iron and aluminum removed solution.

[0106] The second impurity removal step is performed using P204 impurity removal extractant to remove impurities from the iron and aluminum removed solution of the recovered material, thereby obtaining an impurity removed solution. The volume ratio of the P204 impurity removal extractant to the iron and aluminum removed solution is 1:3, the temperature of the impurity removal extraction is 30°C, and the extraction stages are 14 stages.

[0107] Table 1 Specific component table of recovered material

[0108] Raw material Ni Co Mn Fe Mg Si Zn S Cu Al Li Composition % 16.28 7.63 8.6 1.2 0.2 0.1 0.02 0.5 0.8 2.5 3.8

[0109] Table 2 Composition table of the iron and aluminum removed solution of the recovered material

[0110] After iron and aluminium removal Ni Co Mn Li Ca Mg Fe Cd Si Cu Zn Composition g / L After impurity removal 66.2 8.76 13.23 4.92 0.467 1.385 0.007 0.83 8.57 0.453 0.773 4.34

[0111] Table 3 Metal content table in the P204 removed solution

[0112] Ni Co Mn Li Ca Mg Fe Cd Si Cu Zn Composition g / L Solution composition (g / L) 66.1 8.65 12.12 4.90 0.03 0.028 0.0001 0.0001 8.23 0.002 0.0001

[0113] The extraction process is as follows: pyridine carboxylic acid ester and 2- ethylhexyl phosphoric acid 2-ethylhexyl ester are mixed at a volume ratio of 19:1, then mixed with 260# solvent oil at a mass ratio of 1:1 and saponified to obtain a saponified extraction agent, the saponified extraction agent is used for extraction of the removed solution with a pH of 3.5 to obtain an extraction liquid and a raffinate. In the saponification process, the saponifier is sodium soap, the saponification rate is 20%, the extraction temperature is 30°C, the extraction stage is 12 stages, and the volume ratio of the saponified extraction agent to the removed solution is 8:1.

[0114] The back extraction process is as follows: the extraction liquid is washed with dilute sulfuric acid with an acidity of 0.1 mol / L, and then the extraction liquid is back extracted with dilute sulfuric acid with an acidity of 1.5 mol / L to obtain a back extraction liquid.

[0115] Table 4 Valuable metal content table in the raffinate and back extraction liquid

[0116] Ni Co Mn Li Raffinate Strip solution 0.010 0.023 0.011 4.325 After impurity removal 57.531 7.613 11.498 0.003

[0117] The oil removal process is as follows: the back extraction liquid is subjected to oil removal treatment to obtain a battery-grade nickel-cobalt-manganese sulfate solution.

[0118] Table 5 Composition table of the battery-grade nickel-cobalt-manganese sulfate solution

[0119] The lithium extraction process is as follows: the raffinate is subjected to oil removal, impurity removal, evaporation and lithium precipitation to obtain crude lithium carbonate, and the crude lithium carbonate is subjected to carbonization, impurity removal, heating decomposition and centrifugal drying to obtain a battery-grade lithium carbonate.

[0120] Example 2

[0121] The same as example 1, the difference is that the recovered material, the other process parameters, specifically including the following steps:

[0122] The second impurity removal step is as follows: P204 is used for impurity removal extraction of the iron and aluminum removed solution of the recovered material to obtain a removed solution. In the impurity removal extraction process, the volume ratio of the impurity removal extraction agent to the iron and aluminum removed solution is 1:2, the extraction temperature is 40°C, and the extraction stage is 5 stages.

[0123] Table 6 Metal content table in the P204 removed solution

[0124] Ni Co Mn Li Ca Mg Fe Cd Si Cu Zn Composition g / L Solution composition (g / L) 66.05 8.32 12.21 4.89 0.033 0.035 0.0001 0.0001 8.37 0.0025 0.0001

[0125] The extraction process is as follows: pyridine carboxylic acid ester and pyridine phosphoramide (volume ratio 10:1) are mixed with di(2,4,4-trimethylpentyl) phosphonic acid at a volume ratio of 25:3, then mixed with 260# solvent oil at a mass ratio of 1:1 and saponified to obtain a saponified extraction agent, and the saponified extraction agent is used for extraction of the impurity-removed solution with a pH of 3.48 to obtain an extraction solution and a raffinate. In the saponification process, the saponifying agent is sodium soap, the saponification rate is 60%, the extraction temperature is 40°C, the extraction stages are 4, and the volume ratio of the saponified extraction agent to the impurity-removed solution is 7.5:1.

[0126] The back extraction process is as follows: the extraction solution is washed with dilute sulfuric acid with an acidity of 0.3 mol / L, and then back extracted with dilute sulfuric acid with an acidity of 2 mol / L to obtain a back extraction solution.

[0127] Table 7 Content table of valuable metals in the raffinate and back extraction solution

[0128] Ni Co Mn Li Raffinate Strip solution 0.009 0.012 0.013 4.223 After impurity removal 76.708 10.151 15.331 0.001

[0129] The oil removal process is as follows: the back extraction solution is subjected to oil removal treatment to obtain a battery-grade nickel-cobalt-manganese sulfate solution.

[0130] Table 8 Composition table of the battery-grade nickel-cobalt-manganese sulfate solution

[0131]

[0132] The lithium extraction process is as follows: the raffinate is subjected to oil removal, impurity removal, evaporation and lithium precipitation to obtain crude lithium carbonate, which is subjected to carbonization, impurity removal, heating decomposition and centrifugal drying to obtain a battery-grade lithium carbonate.

[0133] Example 3

[0134] The same as example 1, the difference is that the other process parameters, specifically including the following steps:

[0135] The second impurity removal step is as follows: P204 and C272 are used for impurity removal extraction of the iron and aluminum removal solution of the recovered material to obtain an impurity-removed solution. In the impurity removal extraction process, the volume ratio of the impurity removal extraction agent to the iron and aluminum removal solution is 1:0.8, the extraction temperature is 30°C, and the extraction stages are 12.

[0136] Table 9 Metal content table in the P204 and C272 impurity-removed solution

[0137] Ni Co Mn Li Ca Mg Fe Cd Si Cu Zn Composition g / L Solution composition (g / L) 66.13 8.08 10.21 4.80 0.033 0.001 0.0001 0.0001 8.46 0.0002 0.0001

[0138] The pyridine carboxylic acid ester and diisooctyl phosphate are mixed at a volume ratio of 9:1, then mixed with 260# solvent oil at a mass ratio of 1:1 and saponified to obtain a saponified extractant, and the saponified extractant is used for extraction of the impurity-removed solution with a pH of 4.8 to obtain an extract and a raffinate. In the saponification, the saponifying agent is sodium soap, the saponification rate is 50%, the extraction temperature is 30°C, the extraction stages are 10, and the volume ratio of the saponified extractant to the impurity-removed solution is 6:1.

[0139] The extract is washed with dilute sulfuric acid with an acidity of 1 mol / L, and then the extract is back-extracted with dilute sulfuric acid with an acidity of 3 mol / L to obtain a back-extracted solution.

[0140] Table 10 Content table of valuable metals in the raffinate and back-extracted solution

[0141] Ni Co Mn Li Raffinate Strip solution 0.023 0.022 0.035 4.362 After impurity removal 72.436 8.925 12.023 0.005

[0142] The back-extracted solution is subjected to oil removal treatment to obtain a battery-grade nickel-cobalt-manganese sulfate solution, wherein the TOC content in the oil-removed nickel-cobalt-manganese sulfate solution is 2.1 ppm.

[0143] Table 11 Composition table of the battery-grade nickel-cobalt-manganese sulfate solution

[0144]

[0145] The raffinate is subjected to oil removal, impurity removal, and evaporation and lithium precipitation to obtain crude lithium carbonate, and the crude lithium carbonate is subjected to carbonization and impurity removal, heating decomposition, and centrifugal drying treatment to obtain a battery-grade lithium carbonate.

[0146] Example 4

[0147] The same as example 1, the difference is other process parameters, including the following steps:

[0148] The second impurity removal step uses P204 to remove iron and aluminum from the recovered material to obtain an impurity-removed solution. The volume ratio of the impurity removal extractant to the iron and aluminum removal solution is 1:1.5, the extraction temperature is 60°C, and the extraction stages are 10.

[0149] Table 12 Metal content table in the P204 impurity-removed solution

[0150] Ni Co Mn Li Ca Mg Fe Cd Si Cu Zn Composition g / L Solution composition (g / L) 59.69 8.17 12.32 4.88 0.035 0.028 0.0001 0.0001 8.49 0.0022 0.0001

[0151] The extraction process is carried out by mixing pyridine carboxylic acid ester and 2-ethylhexyl phosphonic acid 2-ethylhexyl ester, di(2,4,4-trimethylpentyl) phosphonic acid in a volume ratio of 90:7, mixing with 260# solvent oil in a mass ratio of 1:1 and saponifying to obtain a saponified extraction agent, using the saponified extraction agent to extract the impurity-removed solution with a pH of 3.6 to obtain an extraction liquid and a raffinate. In the saponification process, the saponifying agent is sodium soap, the saponification rate is 60%, the extraction temperature is 60°C, the extraction stages are 8, and the volume ratio of the saponified extraction agent to the impurity-removed solution is 8:1.

[0152] The back-extraction process is carried out by washing the extraction liquid with dilute sulfuric acid with an acidity of 1.5N and then back-extracting the extraction liquid with dilute sulfuric acid with an acidity of 2N to obtain a back-extraction liquid.

[0153] Table 13 Content table of valuable metals in the raffinate and back-extraction liquid

[0154] Ni Co Mn Li Raffinate Strip solution 0.015 0.032 0.023 4.358 Solution composition (g / L) 73.126 9.233 13.458 0.005

[0155] The oil removal process is carried out on the back-extraction liquid to obtain a battery-grade nickel-cobalt-manganese sulfate solution, wherein the TOC content in the oil-removed nickel-cobalt-manganese sulfate solution is 2.0 ppm.

[0156] Table 14 Composition table of the battery-grade nickel-cobalt-manganese sulfate solution

[0157]

[0158] The lithium extraction process is carried out by oil-removing, impurity-removing, and evaporation and lithium precipitation on the raffinate to obtain crude lithium carbonate, and the crude lithium carbonate is carbonized, impurity-removed, heated and decomposed, and centrifuged and dried to obtain a battery-grade lithium carbonate.

[0159] Example 5

[0160] Based on Example 1, in the extraction process, the mass ratio of the second solvent to 260# solvent oil is 1:4, the volume ratio of the saponified extraction agent to the impurity-removed solution is 16:1, and the other process conditions are the same as those in Example 1.

[0161] Example 6

[0162] Based on Example 1, in the extraction process, the volume ratio of pyridine carboxylic acid ester to 2-ethylhexyl phosphonic acid 2-ethylhexyl ester is changed to 1:1, the volume ratio of the saponified extraction agent to the impurity-removed solution is 18:1, and the other process conditions are the same as those in Example 1.

[0163] Example 7

[0164] Based on Example 1, in the extraction process, the volume ratio of pyridine carboxylic acid ester to 2-ethylhexyl phosphonic acid 2-ethylhexyl ester is changed to 100:1, the volume ratio of the saponified extraction agent to the impurity-removed solution is 10:1, and the other process conditions are the same as those in Example 1.

[0165] Example 8

[0166] On the basis of Example 1, the sodium soap in the recovery process is changed to ammonium soap (saponification is performed using ammonia water), the volume ratio of saponification extractant and impurity-removed liquid is 8:1, and other process conditions are the same as in Example 1.

[0167] Table 15 Table of contents of valuable metals in raffinate and stripping solution

[0168] Ni Co Mn Li Raffinate Strip solution 1.235 0.286 0.396 4.325 Composition (g / L) 48.230 5.677 8.748 0.003

[0169] Table 16 Table of contents of valuable metals in raffinate and stripping solution

[0170]

[0171] Comparative Example 1

[0172] On the basis of Example 1, the second solvent is only pyridine carboxylate, and other process conditions are the same as in Example 1, which results in a significant decrease in the recovery rate of manganese.

[0173] Table 17 Table of contents of valuable metals in raffinate and stripping solution

[0174] Ni Co Mn Li Raffinate Composition (g / L) 0.023 0.028 7.62 4.315

[0175] Comparative Example 2

[0176] On the basis of Example 1, the second solvent is only 2-ethylhexyl 2-ethylhexyl phosphonate, and other process conditions are the same as in Example 1.

[0177] Table 18 Table of contents of valuable metals in raffinate and stripping solution

[0178] Ni Co Mn Li Raffinate ​ 1.56 1.08 8.42 3.256

[0179] Test Part

[0180] Recovery rate test of valuable metals

[0181] The raffinate containing lithium obtained in the extraction process and the stripping solution containing nickel, cobalt and manganese obtained in the stripping process;

[0182] 5 mL of the raffinate / stripping solution is taken and diluted with 45 mL of concentrated sulfuric acid to obtain a test sample solution;

[0183] 10 mL of the sample solution is taken and tested in an ICP, and the concentration of each valuable metal in the sample solution is obtained through the test. The total amount of valuable metals in the raffinate / stripping solution is calculated according to the concentration, and the recovery rate of valuable metals (such as Ni, Co, Mn or Li, etc.) is calculated according to the following formula:

[0184] Ni, Co, Mn and Li recovery rate = stripping liquid volume * stripping liquid metal concentration / (liquid volume before extraction * metal concentration before extraction).

[0185] Li comprehensive recovery rate = battery-grade lithium carbonate mass * lithium content of battery-grade lithium carbonate / (battery material mass * lithium content of battery material).

[0186] Table 19: Recovery rates of valuable metals in each example and comparative example

[0187]

[0188] Note: In combination with Table 17 and Table 18, the valuable metal content in the raffinate is high, which leads to the separation effect of nickel, cobalt, manganese and lithium not meeting the requirements, therefore, the comprehensive recovery rate of lithium is not calculated.

[0189] As can be seen from Table 19, from Example 1 to Example 8, using the recovery method provided in the present application, the recovery rate of nickel, cobalt and manganese is as high as 85% or more, the recovery rate of lithium is as high as 80% or more, and the content of impurity metals in the stripping liquid and the raffinate is within the allowable range, that is, the recovery method provided in the present application can realize effective separation of nickel, cobalt, manganese and lithium, and can also reduce the processing cost of nickel, cobalt, manganese and lithium metals, thereby reducing the recovery cost of valuable metals and improving the recovery rate and utilization value of valuable metals.

[0190] Please continue to refer to Table 19, Example 1 compared with Comparative Example 1 and Comparative Example 2, in Comparative Example 1, the second solvent only includes pyridine carboxylic acid ester, which leads to a significant reduction in the recovery rate of manganese, which is only 66.29%, it can be seen that the recovery method provided in the present application can improve the recovery rate of nickel and cobalt, and also improve the recovery rate of manganese, and realize effective separation of nickel, cobalt, manganese and lithium, and the manganese in the stripping liquid can be directly used as battery-grade manganese sulfate, compared with the traditional process, this part of manganese needs to be subjected to a whole extraction and stripping process and then subjected to deep extraction to obtain a battery-grade manganese sulfate solution, which improves the utilization value of manganese. In Comparative Example 2, the second solvent only includes 2-ethylhexyl 2-ethylhexyl phosphonate, which leads to a significant reduction in the recovery rate of manganese, which is only 66.29%, and the recovery rate of nickel and cobalt is also reduced, the recovery rate of nickel is 79.64%, the recovery rate of cobalt is 89.37%, and a large amount of lithium is extracted, causing loss of lithium, and the extraction amount of calcium and magnesium is increased, leading to impurities in the stripping liquid not meeting the standard, and because the equivalent of the stripping acid is low, the stripping process progresses slowly, and the nickel, cobalt and manganese metal ions cannot be effectively enriched. It can be seen that, using the recovery method of the present application, the second solvent contains pyridine extractant and phosphonate extractant, which can effectively separate nickel, cobalt, manganese and lithium, and also improve the recovery rate of nickel, cobalt, manganese and lithium.

[0191] Any of the technical features described above can be combined. Although not all possible combinations of the technical features are described, any combination of the technical features should be considered as being covered by the present specification, as long as such a combination does not result in a contradiction.

[0192] Finally, it should be noted that the above-described embodiments are merely intended to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for recycling valuable metals, characterized in that, The recycling method includes: In the leaching process, the metal-containing recycled material is contacted with an acid solution to leach the metal from the recycled material into the acid solution, thereby obtaining an acid leaching solution. In the impurity removal process, the acid leaching solution is treated with a first solvent to remove impurities, resulting in a purified solution containing a valuable metal. The valuable metal includes a first valuable metal element and a second valuable metal element. The first valuable metal element includes at least one of nickel, cobalt, and manganese, and the second valuable metal element includes lithium. In the extraction process, the purified liquid is extracted using a second solvent to obtain an extract containing a first valuable metal element and a raffinate containing a second valuable metal element, wherein the second solvent includes pyridine extractants and phosphate ester extractants. The extraction process includes: The saponification step involves mixing the second solvent and the diluent and saponifying them to obtain the saponified extractant. The extraction step involves using the saponifying extractant to extract the purified liquid, thereby obtaining an extract containing the first valuable metal element.

2. The recycling method according to claim 1, characterized in that, In the saponification step, the mass ratio of the second solvent to the diluent is 1:(1-4).

3. The recycling method according to claim 1, characterized in that, In the extraction process, the pyridine extractant includes pyridine or pyridyl derivatives.

4. The recycling method according to claim 3, characterized in that, In the extraction process, The volume ratio of the pyridine extractant to the phosphate extractant is (1-100):(1-100).

5. The recycling method according to claim 1, characterized in that, The first solvent includes an alkaline substance and a purification extractant, and the purification process includes: The first impurity removal step involves using an alkaline substance to adjust the pH of the acid leaching solution to 3-5 so that iron and aluminum in the acid leaching solution precipitate, and then separating the solid and liquid to obtain the liquid after removing iron and aluminum. The second impurity removal step involves using an impurity removal extractant to extract and remove impurities from the iron and aluminum-removed liquid, thereby obtaining the impurity-removed liquid containing valence metals.

6. The recycling method according to claim 5, characterized in that, In the second impurity removal step, the volume ratio of the impurity removal extractant to the iron and aluminum removed liquid is 1:(0.8-3).

7. The recycling method according to claim 1, characterized in that, Also includes: The back-extraction process involves back-extracting the extract to obtain a back-extract. The oil removal process involves removing oil from the back-extraction solution.

8. The recycling method according to claim 7, characterized in that, The back-extraction process includes: The washing step involves washing the extract with a first acid solution to obtain a washed liquid. In the back-extraction step, the washing liquid is back-extracted using a second acid solution to obtain a back-extraction solution containing the first valuable metal element.

9. The recycling method according to claim 1, characterized in that, The recyclables include battery recyclables.

10. The recycling method according to claim 1, characterized in that, The saponification rate of the saponification is 20%-80%.

11. The recycling method according to claim 1, characterized in that, The volume ratio of the saponifying extractant to the purified liquid is (4-10):

1.

12. The recycling method according to claim 1, characterized in that, The pH of the purified solution is 3-5, and the extraction temperature is 30℃-60℃.

13. The recycling method according to claim 1, characterized in that, The pyridine extractant includes one or more of pyridine carboxylate and pyridine phosphoramide.

14. The recycling method according to claim 1, characterized in that, The phosphate ester extractant includes one or more of diisooctyl phosphate, 2-ethylhexyl phosphate, tributyl phosphate, and 2,4,4-trimethylpentyl diphosphonic acid.

15. The recycling method according to claim 5, characterized in that, The impurity removal extractant includes phosphoric acid extractants and / or phosphonic acid extractants.

16. The recycling method according to claim 5, characterized in that, The impurity removal extractant includes one or more of P204, P507, and C272.

17. The recycling method according to claim 5, characterized in that, The pH of the solution after iron and aluminum removal is 2-6.

18. The recycling method according to claim 8, characterized in that, The first acid solution contains sulfuric acid and / or hydrochloric acid.

19. The recycling method according to claim 8, characterized in that, The acidity of the first acid solution is 0.1 mol / L to 1.5 mol / L.

20. The recycling method according to claim 8, characterized in that, The second acid solution contains sulfuric acid and / or hydrochloric acid.

21. The recycling method according to claim 8, characterized in that, The acidity of the second acid solution is 1.5 mol / L-3 mol / L.

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