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

Abstract

Provided is a method for recovering nickel, cobalt, and manganese from a compound including metal oxides of nickel, cobalt, and manganese in which the concentration of manganese in recovered materials is kept low while increasing the concentrations of nickel and cobalt.　The method for recovering nickel, cobalt, and manganese includes: a mixing step in which a reducing agent and a compound containing metal oxides of nickel, metal oxides of cobalt, and metal oxides of manganese are mixed and a mixture is produced; and a heating step in which the mixture is heated to obtain a first product and a second product having a higher concentration of manganese than the first product. In the mixing step, one or more substances selected from among carbon reducing agents containing carbon as a component thereof, silicon reducing agents containing silicon as a component thereof, and aluminum reducing agents containing aluminum as a component thereof are 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, from a used lithium-ion battery, and a method for producing a valuable metal.

Background Art

[0002] In recent years, the demand for lithium-ion batteries has been rapidly increasing due to the spread of mobile terminals such as smartphones and notebook computers, and the spread of electric vehicles. In addition, the demand for electric vehicles that do not use fossil fuels is expected to further increase in the future from the perspective of reducing greenhouse gas emissions. Therefore, the demand for lithium-ion batteries is expected to further increase in the future.

[0003] Generally, a lithium-ion battery is composed of a positive electrode material, a negative electrode material, a separator that insulates the positive and negative electrodes, and an electrolyte. Compounds such as nickel, cobalt, and manganese are used for the positive electrode material. Examples of compounds such as nickel, cobalt, and manganese include LiNiO2, LiCoO2, and LiMnO2.

[0004] Nickel, cobalt, and manganese are not abundant resources globally. Therefore, recovering nickel, cobalt, and manganese from the positive electrode material of a used lithium-ion battery is very important from the viewpoints of resource recovery and effective utilization.

[0005] The compounds contained in the positive electrode material are reused by being reduced. Generally speaking, the reduction of the positive electrode material can be roughly classified into two methods: wet treatment and dry treatment. The wet treatment is a method of dissolving the powdered positive electrode material in an acidic solution and recovering nickel, cobalt, and manganese by methods such as solvent extraction and electrolytic refining.

[0006] As an example of wet treatment, after bringing the positive electrode material of a lithium-ion battery into contact with an acid to leach the target metal, nickel, cobalt, and manganese are recovered by performing a plurality of solvent extraction steps, as disclosed in Patent Document 1.

[0007] Dry treatment is a method in which nickel, cobalt, and manganese are reduced by heating a mixture of a powdery positive electrode material and a reducing agent, and then these are separated and recovered from the mixture.

[0008] As an example of dry treatment, a method for recovering valuable elements having a mixing step of mixing a recovered material from a secondary battery, a reducing agent, and a flux, and a reduction step of heating the mixture for reduction treatment is disclosed in Patent Document 2.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, in wet treatment, the amount that can be processed at one time is limited and a long processing time is required. For this reason, there is room for improvement in wet treatment in terms of efficiently recovering metals. In addition, wet treatment requires acids, solvents, etc. for the treatment, so there is a problem that the treatment cost becomes extremely high.

[0011] By the way, by subjecting the metal recovered by dry processing to wet processing, the purity of each metal to be recovered is increased. However, the method for recovering manganese in the wet processing varies depending on the form of manganese dissolved in the acidic solution. That is, since the metal recovered by the dry processing disclosed in Patent Document 2 contains manganese, there is a problem that complicated processing is required in the subsequent wet processing.

[0012] The present invention has been made in view of the above problems, and aims to provide a method for recovering nickel, cobalt, and manganese that increases the concentrations of nickel and cobalt while keeping the concentration of manganese in the recovered product low from a compound containing metal oxides of nickel, cobalt, and manganese. [Means for Solving the Problems]

[0013] To solve the above problems, the present invention has the following features.

[0014] [1] A mixing step of mixing a compound containing a metal oxide of nickel, a metal oxide of cobalt, and a metal oxide of manganese, and a reducing agent to produce a mixture; 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, which is a method for recovering nickel, cobalt, and manganese, 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 are used, and the reducing agent is used in an amount satisfying the following range, a method for recovering nickel, cobalt, and manganese. (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) R: Amount (mol) of the reducing agent X(Ni): Amount (mol) of nickel in the compound X(Co): Amount of cobalt (mol) in the compound X(Mn): Amount of manganese (mol) in the compound a: Molar ratio (mol / mol) of carbon reducing agent in the reducing agent b: Molar ratio (mol / mol) of silicon reducing agent in the reducing agent [2] A method for recovering nickel, cobalt and manganese according to [1], comprising a compound recovery step of recovering the compound containing the metal oxide of nickel, the metal oxide of cobalt and the metal oxide of manganese from a lithium-ion battery. [3] The method for recovering nickel, cobalt and manganese according to [1] or [2], wherein the heating step is carried out at 1400 °C or higher. [4] A dissolution step of dissolving the first product obtained in the heating step in an acid to form a solution, and An extraction step of performing solvent extraction on the solution obtained in the dissolution step, and The method for recovering nickel, cobalt and manganese according to any one of [1] to [3], comprising. [5] A method for producing a valuable metal containing at least one element selected from nickel, cobalt and manganese from a recovered product recovered by using the method for recovering nickel, cobalt and manganese according to any one of [1] to [4].[[]END]]

Advantages of the Invention

[0015] According to the present invention, the first product generated in the heating step and manganese more than the first product Large quantityThe second product can be obtained. Therefore, by performing wet treatment on the first product, nickel and cobalt can be recovered with high efficiency. Further, by performing wet treatment on the second product, manganese can be recovered with high efficiency. That is, it becomes possible to recover nickel, cobalt, and manganese from a compound containing metal oxides of nickel, cobalt, and manganese by a simple operation. Also, it becomes possible to efficiently produce valuable metals.

Brief Description of the Drawings

[0016]

Figure 1

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail. As shown in FIG. 1, the method for recovering nickel, cobalt, and manganese according to the present invention includes a mixing step (step S01) of mixing a compound containing metal oxides of nickel, cobalt, and manganese, and a reducing agent for reducing the metal oxides of nickel, cobalt, and manganese to form a mixture, a heating step (step S02) of heating the mixture to obtain a first product and a second product having a higher manganese concentration than the first product, and a recovery step (step S03) of separating slag and metal after the heating step and recovering each of them.

[0018] Examples of the compound containing metal oxides of nickel, cobalt, and manganese include a positive electrode material of a used lithium-ion battery. In the present embodiment, the case where a positive electrode material of a lithium-ion battery is used as the compound containing metal oxides of nickel, cobalt, and manganese will be described.

[0019] That is, in the method for recovering nickel, cobalt, and manganese, it is preferable to include a compound recovery step of recovering a compound containing nickel metal oxide, cobalt metal oxide, and manganese metal oxide from a lithium-ion battery. The used lithium-ion battery is a battery recovered after being manufactured as a rechargeable battery regardless of its usage state. Examples of the used lithium-ion battery include those whose charge capacity has decreased to a predetermined value or less due to repeated charge and discharge, and those from which unused rechargeable batteries have been recovered.

[0020] A lithium-ion battery is composed of a positive electrode material, a negative electrode material, a separator that insulates the positive and negative electrodes, and an electrolyte. The positive electrode material contains compounds such as nickel, cobalt, and manganese. Examples of the compounds of nickel, cobalt, and manganese include LiNiO2, LiCoO2, and LiMnO2.

[0021] The procedure for recovering the positive electrode material from a lithium-ion battery is carried out 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 then pulverized into a powder.

[0022] In addition, the amount (mol) of nickel, the amount (mol) of cobalt, and manganese quantity of (mol) in the compound of the positive electrode material are respectively shown as follows. X(Ni): The amount (mol) of nickel in the compound X(Co): The amount (mol) of cobalt in the compound X(Mn): The amount (mol) of manganese in the compound

[0023] The amount (mol) of nickel, the amount (mol) of cobalt, and the amount (mol) of manganese in the compound can be measured, for example, by fluorescent X-ray analysis.

[0024] In the mixing step S01, the compound obtained from the positive electrode material by the above method and a reducing agent are mixed to produce a mixture. The reducing agent is a carbon reducing agent containing carbon in its constituent elements , and one or more selected from a silicon reducing agent containing silicon in its constituent elements and an aluminum reducing agent containing aluminum in its constituent elements are used.

[0025] Examples of the carbon reducing agent include graphite, coal, coke, etc.

[0026] As the silicon reducing agent, ferrosilicon, metallic silicon, silicon sludge, etc. can be used.

[0027] As the aluminum reducing agent, in addition to elemental aluminum, for example, aluminum sludge, aluminum dross, etc. can be used.

[0028] The heating step S02 is performed by heating the compacted mixture with a heater. The compacting is performed by filling the mixture obtained in the mixing step into a molding container and then applying pressure to the molding container. By performing the heating step S02, a metal as a first product and a slag as a second product having more manganese than the first product are obtained. Large quantity

[0029] As the heater, for example, an electric 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.

[0030] When heating the mixture, it is preferably performed in an inert gas atmosphere. As the inert gas, for example, Ar, N2 can be used. Also, a reducing gas may be used instead of the inert gas. As the reducing gas, for example, CO, H2 can be used.

[0031] ​The heating temperature is preferably equal to or higher than the melting point of the compound containing nickel metal oxide, cobalt metal oxide and manganese metal oxide. Considering the heating efficiency of the electric furnace, the heating temperature is preferably 1400 - 1600°C, more preferably 1450 - 1600°C, and even more preferably 1450 - 1550°C. When the positive electrode material recovered from the lithium-ion battery is treated at the above-mentioned heating temperature, lithium carbonate is generated by the decomposition reaction of the positive electrode material. The generated lithium carbonate becomes liquid as its melting point is reached by heating, which causes a problem in that it is difficult to handle. In contrast, in this embodiment, lithium is an oxide and its melting point is 500°C or higher than that of lithium carbonate. Therefore, in this embodiment, the lithium oxide transfers to the slag while maintaining its form. Therefore, in this embodiment, the handling problem caused by the above-mentioned liquid state does not occur.

[0032] As the heating temperature increases, the reduction reaction rate increases. Therefore, by increasing the heating temperature, the time of the heating process can be shortened. However, if the heating temperature exceeds 1600°C, there is a risk of evaporation loss of nickel and cobalt. Therefore, the heating temperature is preferably 1600°C or lower.

[0033] In the recovery step of step S03, the metal which is the first product and the slag which is the second product obtained in the heating step of step S02 are separated, and each of the metal and the slag is recovered.

[0034] Next, nickel and cobalt are separated from the metal obtained in the heating step of step S02. Specifically, for example, a dissolution step of dissolving the metal in an acid such as sulfuric acid is performed (step S04). Next, an extraction step (step S05) of performing solvent extraction on the solution in which the metal is dissolved is performed. In the extraction step of step S05, solvent extraction is performed using an extractant, and the solvent containing cobalt is back-extracted.

[0035] As the extractant, for example, a phosphonic acid ester-based one can be used. From the viewpoint of separation efficiency of nickel and cobalt, etc., bis(2-ethylhexyl) phosphonic acid (trade name: PC-88A, Ionquest801) is preferable as the phosphonic acid ester-based extractant.

[0036] Furthermore, after cobalt is extracted, the solution is subjected to solvent extraction using an extractant, and the solvent containing nickel is back-extracted.

[0037] As the extractant, for example, a carboxylic acid-based one can be used. Examples of the carboxylic acid-based extractant include neodecanoic acid, naphthenic acid, etc.

[0038] In addition, as a method for recovering manganese from slag, for example, a method of reheating the slag using carbon, silicon, or aluminum as a reducing agent and performing molten reduction to extract metallic manganese can be mentioned.

[0039] When manganese is contained in the metal, the wet treatment becomes very complicated depending on the form of manganese. Therefore, it is desirable that the metal to be subjected to the wet treatment is free of manganese. Small quantity The method for recovering nickel, cobalt, and manganese according to this embodiment can make the metallic manganese as the first product obtained after the heating step lower than the slag as the second product. Thereby, nickel and cobalt can be recovered with high efficiency by performing wet treatment on the first product. Also, manganese can be recovered with high efficiency by performing wet treatment on the second product. That is, it becomes possible to recover nickel, cobalt, and manganese from a compound containing metal oxides of nickel, cobalt, and manganese with a simple operation. quantity It is preferable to produce a valuable metal containing at least one element selected from nickel, cobalt, and manganese from the recovered product recovered using the above method for recovering nickel, cobalt, and manganese.

[0040]

Example

[0041] Next, using examples and comparative examples, the effects of the method for recovering nickel, cobalt, and manganese of the present invention will be described in detail.

[0042] (Test Example 1: Carbon Reducing Agent Blending Test) The components of the metal obtained by heating a mixture of a compound containing metal oxides of nickel, cobalt, and manganese and a carbon reducing agent were analyzed.

[0043] As the compound containing metal oxides of nickel, cobalt, and manganese, a sample obtained by mixing 1 mol each of NiO, CoO, and MnO was used. Also, as the reducing agent, coke, which is a carbon reducing agent, was used.

[0044] (Mixing Step) The carbon reducing agent was mixed with the sample in the range of 0.9 to 2.7 mol in the manner shown in Table 1 to produce the mixtures according to Examples No. 1 - 6. Similarly, the carbon reducing agent was mixed with the sample in the ranges of 0.7 mol and 3.0 to 4.0 mol to produce the mixtures according to Comparative Examples No. 7 - 9.

[0045] (Heating Step) The mixture obtained in the mixing step was filled into a molding container. Pressure was applied to the molding container from the outside to compact the mixture into a powder. In the heating step, an electric resistance furnace was used as the heater, and it was carried out for 3 hours in an Ar gas atmosphere. In the heating step, the temperature of the electric resistance furnace was maintained at 1450 °C.

[0046] (Component Analysis) After removing the slag as the second product generated in the heating step, the metal as the first product was recovered. The components of the metal of the first product were analyzed using a fluorescent X-ray analyzer. The obtained component analysis results are shown in Table 1. Note that the reduction rate was calculated as the amount of each component in the recovered metal with respect to the amount of each component in the raw material before heating.

[0047]

Table 1

[0048] As shown in Table 1, in Examples 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.

[0049] On the other hand, in Comparative Examples 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%.

[0050] Therefore, in the examples, the concentration of manganese contained in the metal recovered after the heating step is lower than that in the comparative examples. Also, in the examples, the reduction rate of Ni is higher than that in the comparative examples.

[0051] From the results of this test example, the upper limit of the amount R of the reducing agent in this test example can be 2.7 mol. Here, the inventors considered that the upper limit value of the amount R of the reducing agent can be expressed as X(Ni)+X(Co)+α(C)×X(Mn), and obtained α(C)=0.7. Also, if the amount R of the reducing agent is too low, NiO is not reduced and nickel is contained in the slag after the heating step, so the amount of nickel in the metal recovered after the heating step is reduced.

[0052] When the amount R of the reducing agent is 0.7 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 step is reduced.

[0053] 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 is reduced. Therefore, the lower limit value of the amount R of the reducing agent in this experiment was set to 0.9 mol. Here, the inventors considered that the lower limit value can be expressed as β(C)×X(Ni), and obtained β(C)=0.9.

[0054] 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 value of the amount R of this reducing agent corresponds to X(Ni) + X(Co).

[0055] (Test Example 2: Silicon Reducing Agent Blending Test) The components of the metal obtained by heating a mixture of a compound containing metal oxides of nickel, cobalt and manganese and a silicon reducing agent were analyzed.

[0056] As the compound containing metal oxides of nickel, cobalt and manganese, a sample in which 1 mol each of NiO, CoO and MnO was mixed was used. Also, as the reducing agent, metallic silicon which is a silicon reducing agent was used.

[0057] (Mixing Step) The silicon reducing agent was mixed with the sample in the range of 0.45 to 1.35 mol in the manner shown in Table 2 to produce the mixtures according to Examples Nos. 10 - 15. Similarly, the silicon reducing agent was 0.35~2.00 mixed with the sample in the range of mol to produce the mixtures according to Comparative Examples Nos. 16 - 18.

[0058] The heating step and component analysis were carried out in the same manner as in Test Example 1. The obtained component analysis results are shown in Table 2.

[0059] [Table 2]

[0060] The obtained component analysis results are shown in Table 1. As shown in Table 1, in Examples Nos. 10 - 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.

[0061] On the other hand, in Comparative Examples Nos. 16 - 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%.

[0062] Therefore, in the examples, the concentration of manganese contained in the metal recovered after the heating step is lower than that in the comparative examples. Also, in the examples, the reduction rate of Ni is higher than that in the comparative examples.

[0063] From the results of this test example, the upper limit value of the amount R of the reducing agent in this experiment can be set to 1.35 mol. Here, the inventors considered that the upper limit value of the amount R of the reducing agent is expressed as 0.50×X(Ni)+0.50×X(Co)+α(Si)×X(Mn), and obtained α(Si)=0.35. On the other hand, if the amount R of the reducing agent is too low, NiO will not be reduced, and nickel will be contained in the slag after the heating step, so the amount of nickel in the metal recovered after the heating step will decrease.

[0064] 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 step decreases. 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.

[0065] From this, the lower limit value of the amount R of the reducing agent in this experiment was set to 0.45 mol Here, the inventors considered that the lower limit value of the amount R of the reducing agent is expressed as β(Si)×X(Ni), and obtained β(Si)=0.45. Note that when the amount R of the reducing material is 1.25 mol or more, silicon is mixed into the recovered metal, but it does not hinder the recovery when separating and recovering nickel and cobalt in the next wet treatment.

[0066] In addition, 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 value of this amount R of the reducing agent corresponds to 0.50×X(Ni)+0.50×X(Co).

[0067] (Test Example 3: Aluminum Reducing Agent Blending Test) The components of the metal obtained by heating a mixture of a compound containing metal oxides of nickel, cobalt, and manganese and an aluminum reducing agent were analyzed.

[0068] As the compound containing metal oxides of nickel, cobalt, and manganese, a sample in which 1 mol each of NiO, CoO, and MnO was mixed was used. Also, as the reducing agent, metallic aluminum which is an aluminum reducing agent was used.

[0069] (Mixing step) The aluminum reducing agent was mixed with the sample in the range of 0.60 to 1.80 mol in the manner shown in Table 2 to produce the mixtures according to Examples Nos. 19 - 24. Similarly, the aluminum reducing agent was mixed with the sample at 0.47 mol and in the range of 2.00 to 2.67 mol to produce the mixtures according to Comparative Examples Nos. 25 - 27.

[0070] The heating step and component analysis were performed in the same manner as in Test Example 1. The obtained component analysis results are shown in Table 3.

[0071]

Table 3

[0072] The obtained component analysis results are Table 3 shown in. As shown in Table 1, in the examples of Nos. 19 - 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.

[0073] On the other hand, in the comparative examples of Nos. 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%.

[0074] Therefore, in the examples, the concentration of manganese contained in the metal recovered after the heating step was lower than that in the comparative examples. Also, in the examples, the reduction rate of Ni was higher than that in the comparative examples.

[0075] From 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 considered 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 obtained α(Al)=0.47.

[0076] On the other hand, if the amount R of the reducing agent is too low, NiO will not be reduced and nickel will be contained in the slag after the heating process, so the amount of nickel in the metal recovered after the heating process will decrease. 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.

[0077] 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 manganese is not contained in the metal after the heating process, so it can be said that the amount of the reducing agent is appropriate.

[0078] From this, the lower limit of the amount R of the reducing agent in this experiment was set to 0.60 mol. Here, the inventors considered that the lower limit of the amount R of the reducing agent is expressed as β(Al)×X(Ni), and obtained β(Al)=0.60. In addition, when the amount R of the reducing material is 1.67 mol or more, aluminum is mixed in the recovered metal, but it does not interfere with the recovery when nickel and cobalt are separated and recovered in the next wet treatment.

[0079] In addition, 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. This lower limit of the amount R of the reducing agent corresponds to 0.67×X(Ni)+0.67×X(Co).

[0080] The appropriate range of the amount R of the reducing agent described above also holds 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 is preferably set as (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 step can be reduced, and the concentration of manganese contained in the metal after the heating step can be suppressed to a low level.

[0081] (Test Example 4: Metal Recovery Test) Using a carbon reducing agent, a silicon reducing agent, and an aluminum reducing agent, a compound containing nickel metal oxide, cobalt metal oxide, and manganese metal oxide was reduced, and its reduction rate was derived.

[0082] 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 in a powdered form after being crushed and pulverized.

[0083] 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. As a result, the total amount of nickel, cobalt, and manganese in the compound was 0.4 mol. Also, the molar ratio of nickel, cobalt, and manganese was Ni:Co:Mn = 6:2:2.

[0084] The amount X(Ni) of nickel in the compound was X(Ni) = 0.6× 0.4 = 0.24 mol. Similarly, the amount X(Co) of cobalt in the compound was X(Co) = 0.2×0.4 = 0.08 mol. The amount X(Mn) of manganese in the compound was X(Mn) = 0.2×0.4 = 0.08 mol.

[0085] (Hybrid process) In the manner shown in Table 4, a carbon reducing agent, a silicon reducing agent, and an aluminum reducing agent were mixed with a compound to produce a mixture according to Examples Nos. 28 - 45 and a mixture according to Comparative Examples Nos. 46 - 54. Note that graphite was used as the carbon reducing agent. Metallic silicon was used as the silicon reducing agent. Metallic aluminum was used as the aluminum reducing agent.

[0086] A heating process and component analysis were performed in the same manner as in Test Example 1. The resulting component analysis results are shown in Table 4.

[0087]

Table 4

[0088] As shown in Nos. 28 - 33 of Table 4, when a carbon reducing agent is used as the reducing agent, the amount R (mol) of the reducing agent is preferably 0.90×X(Ni) ≦ R ≦ X(Ni) + X(Co) + 0.70×X(Mn). That is, the amount R (mol) of the reducing agent is preferably 0.216 mol ≦ R ≦ 0.376 mol.

[0089] In Examples Nos. 28 - 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 kept low.

[0090] In contrast, in Comparative Example No. 46 where the amount R of the reducing agent was below the above range, the reduction rate of nickel was 69%, which was lower than that of the above examples. Also, in Comparative Example No. 46, the amount of nickel recovered as a metal decreased compared to each of the examples. In Comparative Examples Nos. 47 and 48 where the amount R of the reducing agent exceeded the above range, the reduction rate of nickel was 100%. However, the manganese concentration in the metal of Comparative Examples Nos. 47 and 48 was 17% or more, which was higher than that of Examples Nos. 28 - 33.

[0091] As shown in Nos. 34 - 39 of Table 4, when a silicon reducing agent is used as the reducing agent, the amount R (mol) of the reducing agent is preferably 0.45×X(Ni)≦R≦0.5×X(Ni)+0.5×X(Co)+0.35×X(Mn). That is, the amount R (mol) of the reducing agent is preferably 0.108 mol≦R≦0.188 mol.

[0092] In the examples of Nos. 34 - 39 where the amount R of the reducing agent is within the above range, the reduction rate of nickel is as high as 76% or more, and the concentration of manganese in the recovered metal is also kept low at 4.6% or less.

[0093] On the other hand, in Comparative Example No. 49 where the amount R of the reducing agent is below the above range, the reduction rate of nickel is as low as 70%, and the amount of nickel recovered as metal has decreased. In Comparative Examples Nos. 50 and 51 where the amount R of the reducing agent exceeds the above range, the reduction rate of nickel is 100%. However, in Comparative Examples Nos. 50 and 51, the concentration of manganese in the metal is 16% or more, which is higher than that in the examples of Nos. 34 - 39.

[0094] As shown in Nos. 40 - 45 of Table 4, when an aluminum reducing agent is used as the reducing agent, the amount R (mol) of the reducing agent is preferably 0.60×X(Ni)≦R≦0.67×X(Ni)+0.67×X(Co)+0.47×X(Mn). That is, the amount R (mol) of the reducing agent is preferably 0.144 mol≦R≦0.252 mol.

[0095] In the examples of Nos. 40 - 45 where the amount R of the reducing agent is within the above range, the reduction rate of nickel is as high as 77% or more, and the concentration of manganese in the recovered metal is also kept low at 4.4% or less.

[0096] On the other hand, in Comparative Example No. 52 where the amount R of the reducing agent was below the above range, the reduction rate of nickel was as low as 60%, and the amount of nickel recovered as a metal decreased. In Comparative Examples No. 53 and 54 where the amount R of the reducing agent exceeded the above range, the reduction rate of nickel was 100%. However, the manganese concentration of the metal in Comparative Examples No. 53 and 54 was 12% or more, which was higher than that in Examples Nos. 40 to 45.

Claims

1. A mixing step of mixing a nickel metal oxide, a cobalt metal oxide, a compound containing a manganese metal oxide, and a reducing agent to produce a mixture; A heating step of heating the mixture to obtain a first product and a second product having a higher amount of manganese than the first product, the method for recovering nickel, cobalt, and manganese, comprising: The concentration of manganese in the first product obtained in the heating step is 9.1 mol% or less; 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 are used, and the reducing agent is used in an amount satisfying the following range, the method for recovering nickel, cobalt, and manganese. (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) R: The amount (mol) of the reducing agent X(Ni): The amount (mol) of nickel in the compound X(Co): The amount (mol) of cobalt in the compound X(Mn): The amount (mol) of manganese in the compound a: The molar ratio (mol / mol) of the carbon reducing agent in the reducing agent b: The molar ratio (mol / mol) of the silicon reducing agent in the reducing agent

2. The method for recovering nickel, cobalt, and manganese according to claim 1, comprising 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 carried out at 1400 °C or higher.

4. A dissolving step of dissolving the first product obtained in the heating step in an acid to form a solution; An extraction step of performing solvent extraction on the solution obtained in the dissolving step; The method for recovering nickel, cobalt, and manganese according to claim 1 or 2, comprising:

5. A method for producing a valuable metal containing at least one element selected from nickel, cobalt, and manganese from a recovered product recovered by using the method for recovering nickel, cobalt, and manganese according to claim 1 or 2.

Images