Method for recovering nickel, cobalt, and manganese, and method for producing valuable metal

Abstract

Provided is a method for recovering nickel, cobalt, and manganese from a compound of a metal oxide containing nickel, cobalt, and manganese, the method increasing the concentration of nickel and cobalt while suppressing the concentration of manganese in the recovered product to a low level. The method for recovering nickel, cobalt, and manganese comprises: a mixing step in which a compound containing a metal oxide of nickel, a metal oxide of cobalt, and a metal oxide of manganese, and a reducing agent are mixed to produce a mixture; and a heating step for heating the mixture to obtain a first product and a second product having a higher manganese concentration than the first product. In the mixing step, at least one selected from the group consisting of a carbon reducing agent containing carbon as a constituent element, a silicon reducing agent containing silicon as a constituent element, and an aluminum reducing agent containing aluminum as a constituent element is used as the reducing agent, and the reducing agent is used in an amount satisfying a predetermined range.

Description

Technical Field

[0001] The present invention relates to a method for recovering nickel, cobalt and manganese, for example, by recovering nickel, cobalt and manganese from used lithium-ion batteries, and a method for producing valuable metals. Background Art

[0002] In recent years, the demand for lithium-ion batteries has increased rapidly due to the popularity of mobile terminals such as smartphones and laptops, and the popularity of electric vehicles. In addition, from the perspective of reducing greenhouse gases, it is also believed that the demand for electric vehicles that do not use fossil fuels will increase further in the future. Therefore, it is expected that the demand for lithium-ion batteries will increase further in the future.

[0003] Generally, lithium-ion batteries are composed of a positive electrode material, a negative electrode material, a separator for insulating the positive electrode from the negative electrode, and an electrolyte. The positive electrode material uses a compound of nickel, cobalt, and manganese. Examples of the compound of nickel, cobalt, and manganese include LiNiO2, LiCoO2, and LiMnO2.

[0004] Nickel, cobalt and manganese are not abundant in the world, so it is very important to recover nickel, cobalt and manganese from the positive electrode materials of used lithium-ion batteries from the perspective of recycling and effective utilization of resources.

[0005] The compounds contained in the positive electrode material are recycled by reduction. There are two main methods for reducing positive electrode materials: wet treatment and dry treatment. Wet treatment is a method in which powdered positive electrode materials are dissolved in an acidic solution and nickel, cobalt and manganese are recovered by solvent extraction, electrolytic refining and other methods.

[0006] As an example of wet treatment, Patent Document 1 discloses that a positive electrode material of a lithium ion battery is brought into contact with an acid to leach a target metal, and then a solvent extraction step is performed multiple times to recover nickel, cobalt, and manganese.

[0007] The dry treatment is a method of heating a mixture of a powdered positive electrode material and a reducing agent to reduce nickel, cobalt, and manganese, and then separating and recovering them from the mixture.

[0008] As an example of dry processing, Patent Document 2 discloses a method for recovering valuable elements, which includes a mixing step of mixing recovered materials from secondary batteries, a reducing agent, and a flux, and a reducing step of heating the mixture to perform a reducing treatment.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2016-186113

[0012] Patent Document 2: Japanese Patent Application Publication No. 2021-95628 Summary of the invention

[0013] Problems to be solved by the invention

[0014] However, in wet treatment, the amount that can be treated at one time is limited, and a long treatment time is required. Therefore, there is room for improvement in wet treatment in terms of efficient recovery of metals. In addition, wet treatment requires acid, solvent, etc., so there is a problem of extremely high treatment cost.

[0015] In addition, the purity of each metal recovered by wet treatment of the metal recovered by dry treatment is improved. However, the method of recovering manganese in the wet treatment is different depending on the form of manganese dissolved in the acidic solution. That is, the metal recovered in the dry treatment disclosed in Patent Document 2 also contains manganese, so there is a problem that complicated treatment is required in the subsequent wet treatment.

[0016] The present invention has been made in view of the above-mentioned problems, and its object is to provide a method for recovering nickel, cobalt and manganese from a compound containing metal oxides of nickel, cobalt and manganese, etc., which method increases the concentration of nickel and cobalt while suppressing the concentration of manganese in the recovered product to a low level.

[0017] Methods used to solve problems

[0018] In order to solve the above-mentioned problems, the present invention has the following features. [1]

[0020] A method for recovering nickel, cobalt and manganese, comprising:

[0021] A mixing step of mixing a compound containing a nickel metal oxide, a cobalt metal oxide, and a manganese metal oxide and a reducing agent to form a mixture; and

[0022] a heating step of heating the mixture to obtain a first product and a second product having a higher manganese concentration than the first product,

[0023] In the mixing step, as the reducing agent, one or more selected from a carbon reducing agent containing carbon as a constituent element, a silicon reducing agent containing silicon as a constituent element, and an aluminum reducing agent containing aluminum as a constituent element is used, and the reducing agent is used in an amount satisfying the following range.

[0024] (0.30a-0.15b+0.60) ×

[0025] R: the amount of the above reducing agent (mol)

[0026] X(Ni): The amount of nickel in the above compound (mol)

[0027] X(Co): the amount of cobalt in the above compound (mol)

[0028] X(Mn): the amount of manganese in the above compound (mol)

[0029] a: molar ratio of carbon reducing agent in the above reducing agent (mol / mol)

[0030] b: Molar ratio of silicon reducing agent in the above reducing agent (mol / mol) [2]

[0032] The method for recovering nickel, cobalt and manganese according to [1] includes a compound recovery step of recovering the above-mentioned compounds containing the above-mentioned nickel metal oxide, cobalt metal oxide and manganese metal oxide from a lithium ion battery. [3]

[0034] The method for recovering nickel, cobalt and manganese according to [1] or [2], wherein the heating step is performed at 1400° C. or higher. [4]

[0036] The method for recovering nickel, cobalt and manganese according to any one of [1] to [3], comprising:

[0037] A dissolving step of dissolving the first product obtained in the heating step with an acid to prepare a solution; and

[0038] The solution obtained in the dissolving step is subjected to an extraction step of extracting the solution with a solvent. [5]

[0040] A method for producing valuable metals, wherein valuable metals containing at least one element selected from nickel, cobalt and manganese are produced from a recovered product recovered using the method for recovering nickel, cobalt and manganese described in any one of [1] to [4].

[0041] Effects of the Invention

[0042] According to the present invention, a first product generated in the heating process and a second product having a higher manganese concentration than the first product can be obtained. Therefore, by wet treating the first product, nickel and cobalt can be recovered with high efficiency. In addition, by wet treating the second product, manganese can be recovered with high efficiency. That is, nickel, cobalt and manganese can be recovered from a compound containing metal oxides of nickel, cobalt and manganese by simple operation. In addition, valuable metals can be efficiently manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a process diagram schematically showing the metal recovery method in the present invention. DETAILED DESCRIPTION

[0044] Hereinafter, embodiments of the present invention will be described in detail.

[0045] like Figure 1 As shown, the method for recovering nickel, cobalt and manganese of the present invention includes: a mixing process (step S01) of mixing a compound containing nickel metal oxide, cobalt metal oxide and manganese metal oxide and a reducing agent for reducing the above nickel metal oxide, cobalt metal oxide and manganese metal oxide to generate a mixture; a heating process (step S02) of heating the above mixture to obtain a first product and a second product having a manganese concentration higher than that of the above first product; and a recovery process (step S03) of separating the slag and the metal after the above heating process and recovering them separately.

[0046] As the compound containing nickel metal oxide, cobalt metal oxide and manganese metal oxide, for example, a used positive electrode material of a lithium ion battery can be cited. In this embodiment, the case of using a positive electrode material of a lithium ion battery as a compound containing nickel metal oxide, cobalt metal oxide and manganese metal oxide is described.

[0047] That is, in the method for recovering nickel, cobalt and manganese, it is preferred to include a compound recovery step of recovering a compound containing a metal oxide of nickel, a metal oxide of cobalt and a metal oxide of manganese from a lithium ion battery. A used lithium ion battery is a battery that is recovered after being manufactured as a rechargeable battery regardless of the state of use. Examples of used lithium ion batteries include lithium ion batteries whose charging capacity has decreased to below a specified value due to repeated charging and discharging, and lithium ion batteries after unused rechargeable batteries have been recovered.

[0048] Lithium-ion batteries are composed of a positive electrode material, a negative electrode material, a separator that insulates the positive electrode from the negative electrode, and an electrolyte. The positive electrode material contains compounds such as nickel, cobalt, and manganese. Examples of compounds such as nickel, cobalt, and manganese include LiNiO2, LiCoO2, and LiMnO2.

[0049] The steps for recovering positive electrode materials from lithium-ion batteries are as follows. First, the electrolyte stored in the battery body is removed. Next, the positive electrode material is separated from the battery body. The positive electrode material separated from the battery body is crushed and pulverized into powder.

[0050] In addition, the amount (mol) of nickel, the amount (mol) of cobalt, and the content (mol) of manganese in the compound of the positive electrode material are respectively as shown below.

[0051] X(Ni): The amount of nickel in the compound (mol)

[0052] X(Co): the amount of cobalt in the compound (mol)

[0053] X(Mn): the amount of manganese in the compound (mol)

[0054] The amount (mol) of nickel, the amount (mol) of cobalt, and the amount (mol) of manganese in the compound can be measured by, for example, fluorescent X-ray analysis.

[0055] In the mixing process of step S01, the compound obtained from the positive electrode material by the above method and the reducing agent are mixed to form a mixture. The reducing agent is one or more selected from a carbon reducing agent containing carbon as a constituent element, a silicon reducing agent containing silicon as a constituent element, and an aluminum reducing agent containing aluminum as a constituent element.

[0056] Examples of the carbon reducing agent include graphite, coal, and coke.

[0057] As the silicon reducing agent, ferrosilicon, metallic silicon, silicon mud, or the like can be used.

[0058] As the aluminum reducing agent, in addition to simple aluminum, for example, aluminum mud, aluminum slag, etc. can be used.

[0059] The heating process of step S02 is performed by heating the mixture after powder compacting with a heater. The powder compacting is performed by filling the mixture obtained in the mixing process into a molding container and then applying pressure to the molding container. By performing the heating process of step S02, a slag is obtained as a metal as a first product and a second product having a higher manganese concentration than the first product.

[0060] As the heater, for example, a resistance furnace, a high-frequency melting furnace, a low-frequency melting furnace, a rotary kiln, a vertical furnace, a steelmaking furnace, etc. can be used.

[0061] When the mixture is heated, it can be carried out under an inert gas atmosphere. As the inert gas, for example, Ar or N2 can be used. In addition, a reducing gas can be used instead of the inert gas. As the reducing gas, for example, CO or H2 can be used.

[0062] The heating temperature can be set to be above the melting point of the compound containing nickel metal oxide, cobalt metal oxide and manganese metal oxide. If the heating efficiency of the electric furnace is considered, the heating temperature is preferably 1400-1600°C, more preferably 1450-1600°C, and further preferably 1450-1550°C. It should be noted that if the positive electrode material recovered from the lithium ion battery is treated at the above heating temperature, lithium carbonate is generated by the decomposition reaction of the positive electrode material. The generated lithium carbonate reaches above the melting point due to heating and becomes liquid, so there is a problem of being difficult to handle. In contrast, in the present embodiment, lithium is an oxide, and its melting point is more than 500°C higher than that of lithium carbonate. Therefore, in the present embodiment, the lithium oxide migrates to the slag while maintaining its form. Therefore, in the present embodiment, the problem of handling caused by the liquid state as described above does not occur.

[0063] The reduction reaction rate increases as the heating temperature increases, so the heating process time can be shortened by increasing the heating temperature. It should be noted that when the heating temperature exceeds 1600°C, evaporation loss of nickel and cobalt may occur. Therefore, the heating temperature is preferably below 1600°C.

[0064] In the recovery process of step S03, the metal as the first product and the slag as the second product obtained in the heating process of step S02 are separated, and the metal and the slag are recovered separately.

[0065] Next, nickel and cobalt are separated from the metal obtained in the heating process of step S02. Specifically, for example, a dissolution process (step S04) is performed to dissolve the metal in an acid such as sulfuric acid. Next, an extraction process (step S05) is performed to extract the solution containing the metal with a solvent. In the extraction process of step S05, solvent extraction is performed using an extractant to strip the solvent containing cobalt.

[0066] As the extractant, for example, a phosphonate extractant can be used. As the phosphonate extractant, 2-ethylhexylphosphonate (trade names: PC-88A, Ionquest 801) is preferred from the viewpoint of separation efficiency of nickel and cobalt.

[0067] Furthermore, in the solution from which the cobalt has been extracted, solvent extraction is performed using an extractant to strip off the solvent containing nickel.

[0068] As the extractant, for example, a carboxylic acid-based extractant can be used. Examples of the carboxylic acid-based extractant include neodecanoic acid and cyclohexane acid.

[0069] As a method for recovering manganese from slag, for example, there is a method in which the slag is heated again using carbon, silicon, or aluminum as a reducing agent to be melted and reduced to extract manganese in a metallic state.

[0070] If the metal contains manganese, the wet treatment becomes very complicated due to the form of manganese. Therefore, the metal to be wet treated preferably has a low manganese concentration. The method for recovering nickel, cobalt and manganese of the present embodiment can make the manganese concentration of the metal as the first product obtained after the heating process lower than the slag as the second product. Thus, by wet treating the first product, nickel and cobalt can be recovered with high efficiency. In addition, by wet treating the second product, manganese can be recovered with high efficiency. That is, nickel, cobalt and manganese can be recovered from a compound of metal oxides containing nickel, cobalt and manganese by simple operation.

[0071] It is preferable to produce valuable metals containing at least one element selected from nickel, cobalt and manganese from the recyclate recovered using the above method for recovering nickel, cobalt and manganese.

[0072] Example

[0073] Next, the effects of the method for recovering nickel, cobalt, and manganese according to the present invention will be described in detail using examples and comparative examples.

[0074] (Test Example 1: Carbon Reducing Agent Mixing Test)

[0075] A mixture obtained by mixing a compound containing metal oxides of nickel, cobalt and manganese and a carbon reducing agent was heated, and the components of the metals obtained were analyzed.

[0076] As the compound containing metal oxides of nickel, cobalt and manganese, a sample in which 1 mol of each of NiO, CoO and MnO was mixed was used. In addition, as the reducing agent, coke, which is a carbon reducing agent, was used.

[0077] (Mixing process)

[0078] The carbon reducing agent was mixed with the sample in the range of 0.9 to 2.7 mol as shown in Table 1 to produce the mixtures of Examples No. 1 to 6. Similarly, the carbon reducing agent was mixed with the sample in the range of 0.7 mol and 3.0 to 4.0 mol to produce the mixtures of Comparative Examples No. 7 to 9.

[0079] (Heating process)

[0080] The mixture obtained in the mixing step is filled into a molding container. Pressure is applied to the molding container from the outside to pressurize the mixture. The heating step is performed for 3 hours in an Ar gas atmosphere using a resistance furnace as a heater. During the heating step, the temperature of the resistance furnace is maintained at 1450°C.

[0081] (Component Analysis)

[0082] After removing the slag as the second product generated in the heating process, the metal as the first product is recovered. The metal of the first product is subjected to component analysis using a fluorescent X-ray analyzer. The obtained component analysis results are shown in Table 1. It should be noted that the reduction rate is calculated in the form of the amount of each component in the recovered metal relative to the amount of each component in the raw material before heating.

[0083]

[0084] As shown in Table 1, in Example No. 1-6, the concentration of manganese contained in the metal recovered after the heating step was 9.1 mol % or less, and the reduction rate of Ni was 85% or more.

[0085] On the other hand, in Comparative Example No. 7-9, the concentration of manganese contained in the metal recovered after the heating step was 28.5 mol % or more, or the reduction rate of Ni was 70%.

[0086] Therefore, in the example, the concentration of manganese contained in the metal recovered after the heating step is lower than that in the comparative example. In addition, in the example, the reduction rate of Ni is higher than that in the comparative example.

[0087] According to the results of this test example, the upper limit of the amount R of the reducing agent in this test example can be set to 2.7 mol. Here, the inventors consider that the upper limit of the amount R of the reducing agent can be expressed as X(Ni)+X(Co)+α(C)×X(Mn), and α(C)=0.7 is obtained. In addition, when the amount R of the reducing agent is too low, NiO is not reduced, and the slag after the heating process contains nickel, so the amount of nickel in the metal recovered after the heating process is reduced.

[0088] When the amount R of the reducing agent was 0.7 mol, the reduction rate of Ni was as low as 70%, 30% of NiO was separated as slag, and the amount of nickel in the metal recovered after the heating step was reduced.

[0089] When the amount R of the reducing agent is 0.9 mol or more, the reduction rate of Ni is as high as 85% or more, and the amount of NiO separated as slag decreases, so the lower limit of the amount R of the reducing agent in this experiment is set to 0.9 mol. Here, the inventors consider that the lower limit can be expressed as β(C)×X(Ni), and obtain β(C)=0.9.

[0090] In order to efficiently recover not only Ni but also Co, it is appropriate to set the amount R of the reducing agent to 2 mol or more. The lower limit of the amount R of the reducing agent corresponds to X(Ni)+X(Co).

[0091] (Test Example 2: Silicon reducing agent combination test)

[0092] A mixture obtained by mixing a compound containing metal oxides of nickel, cobalt, and manganese and a silicon reducing agent was heated, and the components of the metals obtained were analyzed.

[0093] As the compound containing metal oxides of nickel, cobalt and manganese, a sample in which 1 mol of each of NiO, CoO and MnO was mixed was used. In addition, as the reducing agent, metal silicon, which is a silicon reducing agent, was used.

[0094] (Mixing process)

[0095] The silicon reducing agent was mixed in the sample in the range of 0.45 to 1.35 mol as shown in Table 2 to produce the mixtures of Examples No. 10 to 15. Similarly, the silicon reducing agent was mixed in the sample in the range of 1.5 to 2.0 mol to produce the mixtures of Comparative Examples No. 16 to 18.

[0096] The heating step and component analysis were performed in the same manner as in Test Example 1. Table 2 shows the obtained component analysis results.

[0097]

[0098] The obtained component analysis results are shown in Table 1. As shown in Table 1, in Examples No. 10 to 15, the concentration of manganese contained in the metal recovered after the heating step was 8.9 mol % or less, and the reduction rate of Ni was 86% or more.

[0099] On the other hand, in Comparative Examples No. 16 to 18, the concentration of manganese contained in the metal recovered after the heating step was 27.6 mol % or more, or the reduction rate of Ni was 70%.

[0100] Therefore, in the example, the concentration of manganese contained in the metal recovered after the heating step is lower than that in the comparative example. In addition, in the example, the reduction rate of Ni is higher than that in the comparative example.

[0101] According to the results of this test example, the upper limit of the amount R of the reducing agent in this experiment can be set to 1.35 mol. Here, the inventors consider that the upper limit of the amount R of the reducing agent is expressed as 0.50×X(Ni)+0.50×X(Co)+α(Si)×X(Mn), and α(Si)=0.35 is obtained. On the other hand, when the amount R of the reducing agent is too low, NiO is not reduced, and nickel is contained in the slag after the heating process, so the amount of nickel in the metal recovered after the heating process is reduced.

[0102] When the amount R of the reducing agent is 0.35 mol, the reduction rate of Ni is as low as 70%, 30% of NiO is separated as slag, and the amount of nickel in the metal recovered after the heating process is reduced. When the amount R of the reducing agent is 0.45 mol or more, the reduction rate of Ni is as high as 86% or more, and the amount of NiO separated as slag is also small, so it can be said that the amount of the reducing agent is appropriate.

[0103] Therefore, the lower limit of the amount R of the reducing agent in this experiment is set to 0.45. Here, the inventors consider that the lower limit of the amount R of the reducing agent is expressed as β(Si)×X(Ni), and obtain β(Si)=0.45. It should be noted that if the amount of reducing material R is 1.25 mol or more, silicon is mixed in the recovered metal, but it does not hinder the recovery when nickel and cobalt are separated and recovered in the subsequent wet treatment.

[0104] In order to efficiently recover not only Ni but also Co, it is appropriate to set the amount R of the reducing agent to 1 mol or more. The lower limit of the amount R of the reducing agent corresponds to 0.50×X(Ni)+0.50×X(Co).

[0105] (Test Example 3: Aluminum reducing agent combination test)

[0106] A mixture obtained by mixing a compound containing metal oxides of nickel, cobalt, and manganese and an aluminum reducing agent was heated, and the components of the metals obtained were analyzed.

[0107] As the compound containing metal oxides of nickel, cobalt and manganese, a sample in which 1 mol of each of NiO, CoO and MnO was mixed was used. In addition, as the reducing agent, metal aluminum, which is an aluminum reducing agent, was used.

[0108] (Mixing process)

[0109] The aluminum reducing agent was mixed in the sample in the range of 0.60 to 1.80 mol as shown in Table 2 to produce the mixtures of Examples No. 19 to 24. Similarly, the aluminum reducing agent was mixed in the sample in the range of 0.47 mol and 2.00 to 2.67 mol to produce the mixtures of Comparative Examples No. 25 to 27.

[0110] The heating step and component analysis were performed in the same manner as in Test Example 1. Table 3 shows the obtained component analysis results.

[0111]

[0112] The obtained component analysis results are shown in Table 1. As shown in Table 1, in Examples No. 19 to 24, the concentration of manganese contained in the metal recovered after the heating step was 8.8 mol % or less, and the reduction rate of Ni was 85% or more.

[0113] On the other hand, in Comparative Examples No. 25-27, the concentration of manganese contained in the metal recovered after the heating step was 27.1 mol % or more, or the reduction rate of Ni was 70%.

[0114] Therefore, in the example, the concentration of manganese contained in the metal recovered after the heating step is lower than that in the comparative example. In addition, in the example, the reduction rate of Ni is higher than that in the comparative example.

[0115] According to the results of this test example, the upper limit of the amount R of the reducing agent in this experiment can be set to 1.80 mol. Here, the inventors consider that the upper limit of the amount R of the reducing agent is expressed as 0.67×X(Ni)+0.67×X(Co)+α(Al)×X(Mn), and obtain α(Al)=0.47.

[0116] On the other hand, when the amount R of the reducing agent is too low, NiO is not reduced, and the slag after the heating process contains nickel, so the amount of nickel in the metal recovered after the heating process decreases. When the amount R of the reducing agent is 0.47 mol, the reduction rate of Ni is as low as 70%, 30% of NiO is separated as slag, and the amount of nickel in the metal recovered after the heating process decreases.

[0117] When the amount R of the reducing agent is 0.60 mol or more, the reduction rate of Ni is as high as 85% or more, the amount of NiO separated as slag is small, and the metal after the heating step does not contain manganese, so it can be said that the amount of the reducing agent is appropriate.

[0118] Thus, the lower limit of the amount R of the reducing agent in this experiment is set to 0.60 mol. Here, the inventors consider that the lower limit of the amount R of the reducing agent is expressed as β(Al)×X(Ni), and obtain β(Al)=0.60. It should be noted that if the amount of reducing material R is 1.67 mol or more, aluminum is mixed in the recovered metal, but it does not hinder the recovery when nickel and cobalt are separated and recovered in the subsequent wet treatment.

[0119] In order to efficiently recover not only Ni but also Co, it is appropriate to set the amount R of the reducing agent to 1.34 mol or more. The lower limit of the amount R of the reducing agent corresponds to 0.67×X(Ni)+0.67×X(Co).

[0120] The appropriate range of the amount R of the reducing agent also applies when the type of the reducing agent is a mixture of a carbon reducing agent, a silicon reducing agent, and an aluminum reducing agent. That is, when the molar ratio of carbon in the reducing agent is a and the molar ratio of silicon is b, the amount R of the reducing agent can be set to (0.30a-0.15b+0.60)×X(Ni)≤R≤(0.33a-0.17b+0.67)×X(Ni)+(0.33a-0.17b+0.67)×X(Co)+(0.23a-0.12b+0.47)×X(Mn). By defining the amount R of the reducing agent in this way, the amount of NiO separated as slag after the heating process can be reduced, and the concentration of manganese contained in the metal after the heating process can be suppressed to a low level.

[0121] (Test Example 4: Metal Recovery Test)

[0122] A compound containing a nickel metal oxide, a cobalt metal oxide, and a manganese metal oxide was reduced using a carbon reducing agent, a silicon reducing agent, and an aluminum reducing agent, and the reduction rate was derived.

[0123] As the compound containing nickel metal oxide, cobalt metal oxide, and manganese metal oxide, a positive electrode material recovered from a used lithium ion battery was used. The positive electrode material used in this test was a material that was crushed and pulverized into a powder.

[0124] The total amount of nickel, cobalt and manganese in the compound was measured using a fluorescent X-ray analyzer, and the molar ratio was derived. The result showed that the total amount of nickel, cobalt and manganese in the compound was 0.4 mol. In addition, the molar ratio of nickel, cobalt and manganese was Ni:Co:Mn=6:2:2.

[0125] The amount of nickel in the compound, X(Ni), is X(Ni)=0.6×n0.4=0.24 mol. Similarly, the amount of cobalt in the compound, X(Co), is X(Co)=0.2×0.4=0.08 mol. The amount of manganese in the compound, X(Mn), is X(Mn)=0.2×0.4=0.08 mol.

[0126] (Mixing process)

[0127] The carbon reducing agent, silicon reducing agent and aluminum reducing agent were mixed with the compound in the manner shown in Table 4 to produce the mixtures of Examples No. 28 to 45 and the mixtures of Comparative Examples No. 46 to 54. It should be noted that graphite was used as the carbon reducing agent, metal silicon was used as the silicon reducing agent, and metal aluminum was used as the aluminum reducing agent.

[0128] The heating step and component analysis were performed in the same manner as in Test Example 1. Table 4 shows the obtained component analysis results.

[0129]

[0130] As shown in No. 28-33 of Table 4, when a carbon reducing agent is used as a reducing agent, the amount of the reducing agent R (mol) can be set to 0.90×X(Ni)≤R≤X(Ni)+X(Co)+0.70×X(Mn). That is, the amount of the reducing agent R (mol) can be set to 0.216 mol≤R≤0.376 mol.

[0131] In Examples No. 28 to 33 where the amount R of the reducing agent was within the above range, the reduction rate of nickel was 79% or more. In these Examples, the concentration of manganese in the recovered metal was also 4.6% or less, which was suppressed to a low level.

[0132] In contrast, in Comparative Example No. 46, in which the amount R of the reducing agent is less than the above range, the reduction rate of nickel is 69%, which is lower than the above examples. In addition, in Comparative Example No. 46, the amount of nickel recovered as metal is lower than that of each example. In Comparative Examples No. 47 and 48, in which the amount R of the reducing agent exceeds the above range, the reduction rate of nickel is 100%. However, the concentration of manganese in the metal of Comparative Examples No. 47 and 48 is 17% or more, which is higher than that of Examples No. 28-33.

[0133] As shown in No. 34-39 of Table 4, when a silicon reducing agent is used as a reducing agent, the amount of the reducing agent R (mol) can be set to 0.45×X(Ni)≤R≤0.5×X(Ni)+0.5×X(Co)+0.35×X(Mn). That is, the amount of the reducing agent R (mol) can be set to 0.108 mol≤R≤0.188 mol.

[0134] In Examples No. 34-39 in which the amount R of the reducing agent was within the above range, the reduction rate of nickel was as high as 76% or more, and the concentration of manganese in the recovered metal was also suppressed to a low level of 4.6% or less.

[0135] In contrast, in Comparative Example No. 49, where the amount R of the reducing agent is below the above range, the nickel reduction rate is as low as 70%, and the amount of nickel recovered as metal is reduced. In Comparative Examples No. 50 and 51, where the amount R of the reducing agent is outside the above range, the nickel reduction rate is 100%. However, in Comparative Examples No. 50 and 51, the concentration of metal manganese is 16% or more, which is higher than that of Examples No. 34 to 39.

[0136] As shown in No. 40-45 of Table 4, when an aluminum reducing agent is used as a reducing agent, the amount of the reducing agent R (mol) can be set to 0.60×X(Ni)≤R≤0.67×X(Ni)+0.67×X(Co)+0.47×X(Mn). That is, the amount of the reducing agent R (mol) can be set to 0.144 mol≤R≤0.252 mol.

[0137] In Examples No. 40 to 45 in which the amount R of the reducing agent was within the above range, the reduction rate of nickel was as high as 77% or more, and the concentration of manganese in the recovered metal was also suppressed to a low level of 4.4% or less.

[0138] In contrast, in Comparative Example No. 52, in which the amount R of the reducing agent is below the above range, the nickel reduction rate is as low as 60%, and the amount of nickel recovered as metal is reduced. In Comparative Examples No. 53 and 54, in which the amount R of the reducing agent is outside the above range, the nickel reduction rate is 100%. However, the manganese concentration of the metal in Comparative Examples No. 53 and 54 is 12% or more, which is higher than that of Examples No. 40 to 45.

Claims

1. A method for recovering nickel, cobalt and manganese, comprising: A mixing step of mixing a compound containing a nickel metal oxide, a cobalt metal oxide, and a manganese metal oxide and a reducing agent to form a mixture; as well as a heating step of heating the mixture to obtain a first product and a second product having a higher manganese concentration than the first product, In the mixing step, as the reducing agent, one or more selected from a carbon reducing agent containing carbon as a constituent element, a silicon reducing agent containing silicon as a constituent element, and an aluminum reducing agent containing aluminum as a constituent element is used, and the reducing agent is used in an amount satisfying the following range: (0.30a-0.15b+0.60) × R: the amount of the reducing agent (mol), X(Ni): the amount of nickel in the compound (mol), X(Co): the amount of cobalt in the compound (mol), X(Mn): the amount of manganese in the compound (mol), a: molar ratio of the carbon reducing agent in the reducing agent (mol / mol), b: molar ratio of the silicon reducing agent in the reducing agent (mol / mol).

2. The method for recovering nickel, cobalt and manganese according to claim 1, wherein: The invention comprises a compound recovery step of recovering the compound containing the nickel metal oxide, the cobalt metal oxide and the manganese metal oxide from a lithium ion battery.

3. The method for recovering nickel, cobalt and manganese according to claim 1 or 2, wherein: The heating step is performed at a temperature above 1400°C.

4. The method for recovering nickel, cobalt and manganese according to any one of claims 1 to 3, wherein: include: a dissolving step of dissolving the first product obtained in the heating step with an acid to prepare a solution; as well as The solution obtained in the dissolving step is subjected to an extraction step of performing solvent extraction.

5. A method for producing a valuable metal, wherein: A valuable metal containing at least one element selected from nickel, cobalt and manganese is produced from a recovered product recovered using the method for recovering nickel, cobalt and manganese according to any one of claims 1 to 4.

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