Alloy powder and method for producing the same, method for producing nickel and cobalt mineral acid salt aqueous solution, method for producing nickel sulfate and cobalt sulfate, and method for producing precursor compound for synthesizing positive electrode material for lithium ion battery

Abstract

To provide a technique capable of increasing acid leachability and shortening leaching time with respect to an alloy powder containing at least nickel, cobalt, and copper, and enabling production of a mineral acid salt aqueous solution containing nickel and cobalt at a high concentration.SOLUTION: An alloy powder contains at least nickel, cobalt, and copper, wherein a content of copper is 25 mass% to 45 mass%, and a specific surface area is 0.07 m2 / g or more. A method for producing the alloy powder includes: a step for preparing an alloy containing at least nickel, cobalt, and copper, wherein a content of copper is 25 mass% to 45 mass%; and a step for obtaining an alloy powder having a specific surface area of 0.07 m2 / g or more by subjecting the alloy that has been prepared to atomization.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an alloy powder and a method for producing the same, a method for producing an aqueous solution of nickel and cobalt mineral salts using the alloy powder, a method for producing nickel sulfate and cobalt sulfate, and a method for producing a precursor compound for synthesizing a positive electrode material for a lithium-ion battery. [Background technology]

[0002] In recent years, lithium-ion secondary batteries have been attracting attention as lightweight, high-power batteries, and their use is expanding in various applications, including automobiles and smartphones. The production of such lithium-ion secondary batteries relies on rare metals, but these rare metals may become depleted in the future. Therefore, the establishment of recycling technologies for these rare metals is urgently needed. For example, nickel and cobalt, which are mainly used in the cathode, and copper, which is used in the anode, are expensive metals and are treated as valuable metals. In particular, copper, which is used in electrical circuits, is in extremely high demand due to the expansion of renewable energy, and more efficient recycling technologies are needed.

[0003] For example, Patent Document 1 discloses a technology for recycling lithium-ion secondary batteries. Specifically, it discloses a method for producing raw materials with increased concentrations of metals used in lithium-ion battery positive electrode materials, such as nickel and cobalt, by crushing, heat-treating, and sieving lithium-ion secondary batteries. In this way, the production of raw materials with increased proportions of valuable metals from scrap lithium-ion secondary batteries is being considered.

[0004] Patent Document 2 discloses a method for recovering scrap from lithium-ion secondary batteries by crushing and sieving the scrap, melting the entire amount at high temperature, and separating it into a valuable metal alloy of nickel, cobalt, and copper and slag. This method describes that by controlling the mass ratio of copper to nickel and cobalt, reduction melting can be performed at a lower temperature and at a lower cost than conventional methods.

[0005] Furthermore, Patent Document 3 discloses a technology for improving the acid leaching properties of alloy powder produced from, for example, waste lithium-ion batteries by controlling the oxygen content and particle size (D50) compared to conventional methods.

[0006] As in the above-described prior art, an aqueous solution of nickel and cobalt mineral acid salts can be produced by leaching an alloy powder containing nickel, cobalt, and copper, which is produced from raw materials including waste lithium-ion batteries, with a mineral acid such as sulfuric acid. However, no study has been made on the concentrations of nickel and cobalt in the produced aqueous solution of mineral acid salts, or on the overall leaching time. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-174032 [Patent Document 2] Patent Publication No. 2021-165415 [Patent Document 3] Japanese Patent Publication No. 2022-039445 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, an object of the present invention is to provide a technology that can improve the acid leaching properties of an alloy powder containing at least nickel, cobalt, and copper, shorten the leaching time, and produce an aqueous solution of nickel and cobalt mineral acid salts containing nickel and cobalt at high concentrations. [Means for solving the problem]

[0009] When an alloy powder containing nickel, cobalt, and copper is leached with a mineral acid to obtain an aqueous solution of nickel and cobalt mineral salts, if the copper content in the alloy powder is high, the nickel and cobalt concentrations in the aqueous solution of nickel and cobalt mineral salts produced will be low.On the other hand, if the copper content in the alloy powder is too low, the amounts of nickel and cobalt in the alloy powder will be relatively high, and it will take a long time to leach the nickel and cobalt.

[0010] As a result of extensive research, the present inventors have focused on the copper content and specific surface area of ​​alloy powders containing at least nickel, cobalt, and copper, and have discovered that by producing alloy powders in which the copper content and specific surface area are controlled within specific ranges, the above-mentioned trade-off relationship can be resolved, acid leaching properties can be improved, and an aqueous solution of nickel and cobalt mineral acid salts containing high concentrations of nickel and cobalt can be produced, thereby completing the present invention.

[0011] (1) The first aspect of the present invention is an alloy powder containing at least nickel, cobalt, and copper, wherein the copper content is 25% by mass to 45% by mass, and the specific surface area is 0.07 m 2 / g or more.

[0012] (2) A second aspect of the present invention is the alloy powder of the first aspect, wherein the total content of nickel and cobalt is 30 mass % or more.

[0013] (3) A third aspect of the present invention is a method for producing the alloy powder according to the first aspect of the present invention, comprising the steps of: preparing an alloy containing at least nickel, cobalt, and copper, the copper content of which is 25% by mass to 45% by mass; and atomizing the prepared alloy to produce an alloy having a specific surface area of ​​0.07 m. 2 and obtaining an alloy powder having a molecular weight of at least 1 / g.

[0014] (4) A fourth aspect of the present invention is a method for producing alloy powder according to the third aspect, wherein the alloy is obtained by subjecting raw materials including waste battery materials to a pyrometallurgical process including a reduction melting treatment.

[0015] (5) A fifth aspect of the present invention is a method for producing an aqueous solution of nickel and cobalt sulfate salts by using the alloy powder according to the first aspect of the present invention, which comprises leaching nickel and cobalt from the alloy powder with a mineral acid to produce an aqueous solution of mineral acid salts of nickel and cobalt.

[0016] (6) A sixth aspect of the present invention is a method for producing an aqueous solution of nickel and cobalt mineral acid salts, comprising the steps of: immersing the alloy powder in a mineral acid solution in the presence of one or more sulfiding agents selected from hydrogen sulfide, solid sulfur, sodium hydrogen sulfide, and sodium sulfide, thereby leaching nickel and cobalt from the alloy powder.

[0017] (7) A seventh aspect of the present invention is a method for producing an aqueous solution of nickel and cobalt mineral salts, wherein the acid is sulfuric acid in the fifth or sixth aspect of the present invention, and an aqueous solution of nickel and cobalt sulfates is produced.

[0018] (8) An eighth aspect of the present invention is a method for producing nickel sulfate and cobalt sulfate, comprising the steps of: carrying out the production method according to the fifth aspect of the present invention using sulfuric acid as the mineral acid to obtain an aqueous solution of nickel and cobalt sulfates; and performing a solvent extraction treatment on the aqueous solution of sulfates to extract and remove impurities, thereby obtaining a purified mixed aqueous solution of nickel sulfate and cobalt sulfate.

[0019] (9) A ninth aspect of the present invention is a method for producing nickel sulfate and cobalt sulfate according to the eighth aspect of the present invention, further comprising a step of crystallizing the obtained mixed aqueous solution to obtain a mixed salt of nickel sulfate and cobalt sulfate.

[0020] (10) A tenth aspect of the present invention is a method for producing a precursor compound for synthesizing a positive electrode material for a lithium ion battery, the method comprising the steps of: carrying out the production method of claim 5 to produce an aqueous solution of nickel and cobalt mineral salts; purifying the aqueous solution of nickel and cobalt mineral salts to obtain an aqueous solution containing purified nickel and cobalt; and adding hydroxides or carbonates to the aqueous solution containing purified nickel and cobalt to precipitate nickel and cobalt as hydroxides or carbonates, thereby obtaining a solid suitable for synthesizing the positive electrode material for a lithium ion battery. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a technology that can improve the acid leaching property of an alloy powder containing at least nickel, cobalt, and copper, shorten the leaching time, and produce an aqueous solution of mineral acid salts containing nickel and cobalt at high concentrations. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a graph showing the relationship between the specific surface area of ​​the alloy powder and the leaching time. [Figure 2] 1 is a graph showing the relationship between the copper content of the alloy powder and the leaching time. DETAILED DESCRIPTION OF THE INVENTION

[0023] Specific embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope that does not change the gist of the present invention. In this specification, the expression "X to Y" (X and Y are arbitrary numerical values) means "at least X and at most Y."

[0024] ≪1. Alloy powder≫ The alloy powder according to the present embodiment is an alloy powder containing at least nickel, cobalt, and copper. For example, this alloy powder is subjected to a hydrometallurgical process such as acid leaching, and the nickel and cobalt are separated and recovered from the copper, and the recovered alloy powder is used as a raw material for producing a positive electrode material for a lithium-ion battery.

[0025] Specifically, the alloy powder contains at least nickel, cobalt, and copper, the copper content being 25% by mass to 45% by mass, and the specific surface area being 0.07 m 2 / g or more.

[0026] As will be described in detail later, the alloy powder is obtained by atomizing raw materials containing nickel, cobalt, and copper, such as waste battery materials.

[0027] The raw materials for producing the alloy powder are not particularly limited, but from the viewpoint of resource recycling, they are preferably selected from products or scrap containing large amounts of nickel or cobalt. Examples include cathode and anode materials from used lithium-ion secondary batteries (waste batteries), and scrap lithium-ion batteries, cathode and anode materials generated as defective products during the manufacturing process. These are collectively referred to as "waste battery materials." Furthermore, the waste batteries may include other batteries such as nickel-metal hydride batteries in addition to lithium-ion secondary batteries. Furthermore, these waste battery materials may be used as the main raw material to which metallic copper, nickel, and cobalt, copper oxide, nickel oxide, cobalt oxide, ore, etc., have been added.

[0028] The alloy powder according to this embodiment has a copper content of 25% to 45% by mass. Preferably, the copper content is 25% to 40% by mass, and more preferably, the copper content is 30% to 40% by mass. By ensuring that the copper content in the alloy powder is 25% by mass or more, it is possible to maintain high concentrations of nickel and cobalt in the aqueous solution of mineral acid salts of nickel and cobalt obtained by acid leaching the alloy powder. By ensuring that the copper content in the alloy powder is 45% by mass or less, it is possible to increase the leaching rate of nickel and cobalt during acid leaching of the alloy powder, thereby improving efficiency.

[0029] Furthermore, the contents of nickel and cobalt other than copper and other inevitable impurities in the alloy powder are not particularly limited. From the viewpoint of recovering nickel and cobalt from the alloy powder, the total content of nickel and cobalt is preferably 30% by mass or more, and more preferably 50% by mass or more. Furthermore, examples of inevitable impurities include iron, manganese, zinc, phosphorus, aluminum, etc., and the contents of these are preferably 15% by mass or less. By keeping the content of inevitable impurities at 15% by mass or less, nickel and cobalt can be efficiently recovered in a hydrometallurgical process including acid leaching using the alloy powder, and the load on the hydrometallurgical process can be reduced.

[0030] If the analyzed copper content of the alloy powder is lower than the range of the above-mentioned content, the content can be adjusted by adding copper powder or copper oxide to the alloy powder, etc. Even if the analyzed copper content is higher than the range of the above-mentioned content, the copper content can be relatively adjusted by adding metallic nickel or cobalt, nickel oxide or cobalt oxide, etc.

[0031] The content of metal elements in the alloy powder can be analyzed by inductively coupled plasma mass spectrometry (ICP-MS). For example, an Agilent ICP5100 ICP atomic emission spectrometer can be used as the ICP-MS device. The content of metal elements is analyzed by sampling 0.1 to 1.0 g of the alloy powder and dissolving it in a mixed acid of nitric acid, hydrochloric acid, and bromine, with the concentration and other parameters adjusted as appropriate. Random sampling is used for the analysis sample. Random sampling methods include random extraction. In addition, with the ICP-MS method, it is preferable to perform the measurement five times and use the average value as an index.

[0032] The alloy powder according to the present embodiment has a specific surface area of ​​0.07 m 2 / g or more. Preferably, the specific surface area is 0.09 m or more. 2 / g or more. 2 / g or more, the leaching rate of nickel and cobalt can be improved in acid leaching of the alloy powder, and an aqueous solution of mineral acid salts of nickel and cobalt can be efficiently obtained.

[0033] Since the alloy powder is an alloy, it becomes active as the specific surface area increases and is treated as a dangerous material. In addition, the reaction rate between the metal in the alloy powder and the acid may become too high, which may cause heat generation. Therefore, although there are no particular restrictions on the upper limit of the specific surface area, from the viewpoint of facilitating control and management in the manufacturing process, it is set to 0.20 m 2 Thus, the specific surface area of ​​the alloy powder is preferably 0.07 m / g or less. 2 / g~0.20m 2 / g is preferred, and 0.07m 2 / g~0.15m 2 / g is more preferred, and 0.09m 2 / g~0.15m 2 / g is more preferred.

[0034] The specific surface area of ​​the alloy powder can be analyzed by the BET method. It is preferable to use a volumetric method for the BET method. The gas used for this is preferably nitrogen gas or krypton gas. While this depends on the specifications of the instrument, krypton gas is preferred due to its higher analytical accuracy. In the BET method, for example, 20 to 30 g of alloy powder is randomly sampled, and the measurement is repeated five times to obtain the average value. The random sampling method can be the same as that for the ICP-MS method described above.

[0035] 2. Manufacturing method of alloy powder The alloy powder having the above-described properties can be produced as follows: That is, the method for producing the alloy powder according to the present embodiment includes a preparation step of preparing an alloy containing at least nickel, cobalt, and copper, with the copper content being 25% by mass to 45% by mass, and an atomization process of the prepared alloy to produce an alloy having a specific surface area of ​​0.07 m 2 and a powdering step to obtain an alloy powder of at least 1000 kJ / g.

[0036] [Preparation process] In the preparation step, an alloy containing at least nickel, cobalt, and copper, with the copper content being 25% by mass to 45% by mass, is prepared.

[0037] The alloy to be prepared is not particularly limited, but can be obtained, for example, by subjecting waste battery materials, such as used lithium-ion batteries, defective batteries generated during the manufacturing process, scrap cathode materials, and anode materials, to a pyrometallurgical process. Note that the cathode materials and anode materials of lithium-ion batteries contain valuable metals such as nickel, cobalt, and copper.

[0038] Pyrometallurgical processes are methods of changing the physical or chemical properties of raw materials by heat treatment. Specifically, in pyrometallurgical processes, raw materials are heated to high temperatures in a melting furnace and reduced to melt, and the material is separated into an alloy containing valuable metals and slag by utilizing its affinity for oxygen. This allows nickel, cobalt, and copper contained in raw materials such as waste battery materials to be separated into the alloy, while other impurities such as aluminum, iron, manganese, and zinc are separated into the slag.

[0039] In the preparation step, the copper content in the alloy obtained through the pyrometallurgical process as described above is adjusted to 25% by mass to 45% by mass.

[0040] For example, in an alloy obtained using waste battery materials as raw materials, the contents of nickel, cobalt, and copper are determined by the mixing ratio of waste lithium-ion batteries and the like in the raw materials. Therefore, one method for adjusting the copper content in the alloy is to control the mixing ratio of the original raw materials used to obtain the alloy. Specifically, if the copper content of the resulting alloy is high, the raw material composition is adjusted by adding cathode material or cathode material scrap from waste lithium-ion batteries with a high nickel content, nickel powder, or cobalt powder. On the other hand, if the copper content of the resulting alloy is low, the raw material composition is adjusted by adding copper scrap, anode material, or copper powder with a high copper content.

[0041] Alternatively, when the raw material is supplied to the pyrometallurgical process, the adjustment may be performed by controlling the sieve size of the raw material containing the waste battery material after crushing and pulverization, thereby managing the undersize fraction having a high content of nickel and cobalt and the oversize fraction having a high content of copper.

[0042] [Powdering process] In the powdering process, the prepared alloy is powdered to a specific surface area of ​​0.07m 2 / g or more. The powdering method is not particularly limited, but atomization treatment such as water atomization or gas atomization is preferred. Among these, it is particularly preferred to produce alloy powder by atomization treatment using water atomization, since it can effectively increase the specific surface area per unit mass of the alloy powder and can be processed inexpensively.

[0043] (Atomization method) The method of atomizing an alloy to powder will be described in more detail below, taking as an example a water atomization process. Hereinafter, the alloy to be atomized will also be referred to as an "alloy raw material." Furthermore, the alloy powder obtained by atomizing the alloy raw material will also be referred to as an "atomized powder."

[0044] Atomization by water atomization can be performed using known methods. Specifically, first, prepared alloy raw materials are placed in a crucible furnace or a high-frequency induction furnace, and the alloy raw materials are heated and melted in the furnace to form a fluid molten alloy. The heating temperature is preferably about 1350°C to 1600°C in order to obtain the desired atomized powder. In this case, if the copper content of the alloy raw materials is 25% by mass or more, the melting temperature can be kept low, making the material easier to handle. For example, if the copper content is 25% by mass to 45% by mass, a melting temperature of about 1350°C to 1500°C is possible, which is efficient.

[0045] The resulting molten alloy is then poured into a tundish and allowed to fall into the chamber of an atomizing device. Water is sprayed onto the falling molten alloy from a water atomizing nozzle, causing it to split, cool, and solidify, resulting in alloy powder. The amount of water sprayed is approximately 5 to 7 times the mass of the falling molten alloy. The resulting alloy powder is collected by a slurry pump, transported to a collection container, and dried. To prevent air from entering the chamber, the internal pressure is preferably maintained above atmospheric pressure using an inert gas such as nitrogen gas. Nitrogen gas or argon gas is preferably used as the inert gas.

[0046] In an atomizing device, alloy powder with a desired specific surface area can be obtained by adjusting the nozzle structure and injection conditions for injecting water at high pressure. For example, it is known that reducing the injection angle of water from the nozzle causes the alloy powder to become coarse and approach spherical shape, so the specific surface area can be increased by increasing the injection angle and increasing the water pressure.

[0047] Specifically, the spray angle of the water sprayed from the high-pressure water nozzle is not particularly limited, but is preferably 15° to 25° relative to the falling molten alloy. By adjusting the spray angle to this extent, it is possible to reduce the particle size and obtain alloy powder with an irregular shape and low sphericity. This allows for the production of alloy powder with the desired high specific surface area.

[0048] The pressure of the sprayed water is not particularly limited, but is preferably 10 MPa to 100 MPa, and more preferably 20 MPa to 40 MPa. By setting the pressure to 10 MPa or more, the particle size of the obtained alloy powder can be made small. On the other hand, by setting the pressure to 100 MPa or less, excessive fineness can be prevented. By preventing the particle size of the alloy powder from becoming too small, the alloy powder can react stably with the acid during the acid leaching treatment.

[0049] Furthermore, the fewer coarse particles in the alloy powder, the shorter the acid leaching time for nickel and cobalt in the alloy powder. To prevent the formation of coarse particles, for example, methods such as increasing the water injection angle or increasing the jet swirl angle can be used. Furthermore, to reduce the sphericity of the resulting alloy powder and increase its specific surface area, methods such as increasing the proportion of water injected into the molten alloy and increasing the cooling rate can be used.

[0050] For example, in the atomization process using the water atomization method, the specific surface area is preferably 0.07 m under the above-mentioned conditions. 2 / g or more alloy powder can be produced.

[0051] ≪3. Hydrometallurgical process for alloy powder (recovery of valuable metals)≫ By subjecting the alloy powder having the above-mentioned properties to a hydrometallurgical process, the valuable metals nickel and cobalt contained in the alloy powder can be separated from copper and recovered. The hydrometallurgical process refers to the production of valuable metals contained in the alloy powder through acid treatment, refining treatment, etc.

[0052] [Method for producing aqueous solution of nickel and cobalt mineral salts] Specifically, the alloy powder according to this embodiment contains at least nickel, cobalt, and copper, and by subjecting the alloy powder to a leaching treatment using a mineral acid, the nickel and cobalt are selectively leached and separated from the copper, thereby obtaining an aqueous solution of mineral acid salts of nickel and cobalt. In particular, the alloy powder according to this embodiment has a copper content of 25% to 45% by mass and a specific surface area of ​​0.07 m 2 / g or more, it is possible to improve the acid leaching property and obtain an aqueous solution of mineral acid salts containing nickel and cobalt at high concentrations.

[0053] Therefore, a method for producing an aqueous solution of nickel and cobalt mineral salts by leaching nickel and cobalt from an alloy powder with a mineral acid can be defined, where the resulting aqueous solution of mineral salts is a leachate obtained by acid leaching, and is a mixed aqueous solution of mineral salts of nickel and cobalt.

[0054] The mineral acid used in the acid leaching process can be sulfuric acid, hydrochloric acid, or the like, but sulfuric acid is particularly preferred. By carrying out the acid leaching using sulfuric acid, an aqueous solution of nickel and cobalt sulfates can be produced. The amount of acid is not particularly limited, but is preferably in the range of 1 to 15 equivalents relative to the total amount of nickel and cobalt contained in the alloy powder. When sulfuric acid is used, for example, the amount of acid is the equivalent calculated by the following reaction equations [i] and [ii]. Ni + H2SO4 → NiSO4 + H2 [i] Co+H2SO4→ CoSO4+H2...[ii]

[0055] In addition, in the acid leaching process, nickel and cobalt are preferably leached from the alloy powder by immersing the alloy powder in an acid solution in the presence of a sulfurizing agent. For example, in an acid leaching process using a sulfuric acid solution as the mineral acid and solid sulfur as the sulfurizing agent, the alloy powder is immersed in the sulfuric acid solution in the presence of sulfur, and nickel and cobalt in the alloy powder are dissolved into the sulfuric acid solution, forming an aqueous solution of nickel and cobalt sulfates. Meanwhile, copper, which has low solubility, reacts with sulfur to become copper sulfate and precipitate. In this way, acid leaching in the presence of a sulfurizing agent allows nickel and cobalt to be selectively present in the aqueous solution of sulfates, effectively separating copper from nickel and cobalt.

[0056] Examples of sulfurizing agents include hydrogen sulfide, solid sulfur, sodium hydrogen sulfide, and sodium sulfide. When using solid sulfur, it is preferable to grind it appropriately to facilitate the sulfurization reaction. The amount of sulfurizing agent is not particularly limited, but is preferably at least 1 equivalent of the amount of copper contained in the alloy powder in sulfur equivalent. The amount of sulfurizing agent is calculated from the equivalent amount that forms the sulfurizing agent shown in the following reaction formula [iii]. Cu + S → CuS [iii]

[0057] Furthermore, when acid leaching is performed in the presence of a sulfurizing agent, the alloy powder may be immersed in a mineral acid under predetermined conditions, and then the sulfurizing agent may be added to a solution containing the alloy powder immersed in the mineral acid to leach nickel and cobalt. By preliminarily immersing the alloy powder in a mineral acid for a predetermined period of time, the surface condition of the alloy powder can be changed, and the leaching rate of nickel and cobalt can be increased, allowing nickel and cobalt to be leached in a short time after the addition of the sulfurizing agent.

[0058] By the above-described process, copper is separated from nickel and cobalt, and the separated copper may be recovered and recycled, for example, in copper smelting processes.

[0059] [Method for producing a mixed aqueous solution of nickel sulfate and cobalt sulfate] In the above-described method for producing an aqueous solution of nickel and cobalt mineral salts, an aqueous solution of nickel and cobalt sulfates can be obtained by acid leaching using, for example, sulfuric acid as the mineral acid. The resulting aqueous solution of nickel and cobalt sulfates contains nickel and cobalt. However, if the alloy powder is produced using waste battery materials as raw materials, the aqueous solution may contain impurities such as aluminum, iron, manganese, and zinc due to the raw materials. Therefore, the produced aqueous solution of nickel and cobalt sulfates can be purified to remove the impurities and obtain a purified aqueous solution. The purified aqueous solution is an aqueous solution of concentrated nickel and cobalt sulfates.

[0060] The purification treatment for the aqueous solution of nickel and cobalt sulfates is not particularly limited, but examples include a solution purification treatment, a solvent extraction treatment, etc. In the purification treatment, depending on the types of impurity components contained in the aqueous solution, any one treatment may be performed alone, or two or more treatments may be performed in combination.

[0061] (liquid purification treatment) Examples of the liquid purification treatment include oxidation treatment and oxidation neutralization treatment.

[0062] Specifically, in the oxidation neutralization treatment, an oxidizing agent is added to an aqueous solution of nickel and cobalt sulfates to cause an oxidation reaction, and a neutralizing agent is added to control the pH of the solution within a predetermined range, thereby producing a precipitate of impurity components such as iron and phosphorus contained in the aqueous solution. In this way, by performing the oxidation neutralization treatment as a solution purification treatment, the impurities can be separated as precipitates, and a purified aqueous solution of nickel and cobalt sulfates can be obtained.

[0063] As the oxidizing agent, conventionally known oxidizing agents such as hydrogen peroxide, hypochlorous acid, oxygen, etc. are usable. The addition of the oxidizing agent is preferably controlled within a predetermined range by monitoring the oxidation-reduction potential (ORP) of the aqueous solution. Specifically, the oxidizing agent is added to the solution to control the ORP within a range of 380 mV to 430 mV, for example, based on a silver / silver chloride electrode.

[0064] After the oxidizing agent is added to cause an oxidation reaction, a neutralizing agent is added to adjust the pH of the aqueous solution to preferably within the range of 3.8 to 4.5. By controlling the pH within this range and carrying out the neutralization treatment, impurities such as iron and phosphorus can be effectively precipitated. As the neutralizing agent, conventionally known alkalis such as sodium hydroxide and potassium hydroxide can be used.

[0065] In the oxidation neutralization treatment, the oxidizing agent may be added after the neutralizing agent is added to the aqueous solution of nickel and cobalt sulfates. However, it is preferable to add the oxidizing agent and the neutralizing agent simultaneously, or to add the oxidizing agent first and then the neutralizing agent.

[0066] (Solvent extraction treatment) In the solvent extraction treatment, impurities contained in an aqueous solution of nickel and cobalt sulfates or an aqueous solution obtained through a solution purification treatment are selectively extracted into an organic solvent, and the impurities are separated and removed to obtain a purified mixed aqueous solution of nickel sulfate and cobalt sulfate. Alternatively, nickel and cobalt contained in the aqueous solution of nickel and cobalt sulfates may be selectively extracted into an organic solvent, and then back-extracted with sulfuric acid to separate and remove the impurities to obtain a purified mixed aqueous solution of nickel sulfate and cobalt sulfate.

[0067] The solvent extraction treatment can be carried out by a conventionally known method using an acidic extractant or the like. The extractant to be used is selected depending on the metal element to be extracted. Furthermore, during extraction, the extractant is diluted with a hydrocarbon organic solvent or the like. The concentration of the extractant in the organic solvent is not particularly limited, but taking into consideration phase separation and the like, it is preferably 5% to 30% by volume, more preferably 10% to 25% by volume.

[0068] The obtained mixed aqueous solution of nickel sulfate and cobalt sulfate is then subjected to a crystallization treatment, whereby a mixed salt of nickel sulfate and cobalt sulfate can be produced.

[0069] [Method for producing an aqueous nickel sulfate solution and method for producing an aqueous cobalt sulfate solution] In the above-described solvent extraction treatment, an extractant that selectively extracts either nickel or cobalt contained in the aqueous solution of nickel and cobalt sulfates may be used, and then the extracted nickel or cobalt may be back-extracted with sulfuric acid, thereby producing an aqueous nickel sulfate solution or an aqueous cobalt sulfate solution, respectively.

[0070] Specifically, for example, cobalt is extracted from an aqueous solution of nickel and cobalt sulfate using an extractant that selectively extracts cobalt, and then the cobalt is stripped with sulfuric acid to produce an aqueous cobalt sulfate solution. Solid cobalt sulfate can be precipitated by subjecting the aqueous cobalt sulfate solution to a crystallization treatment. A nickel sulfate aqueous solution, which is the residual liquid after the solvent extraction, can then be obtained as a purified product. Solid nickel sulfate can be precipitated by subjecting the aqueous nickel sulfate solution to a crystallization treatment. The order of extraction of cobalt and nickel may be reversed.

[0071] The extractant used in the solvent extraction treatment is not particularly limited, and may be, for example, a phosphate ester-based organic solvent, of which bis(2-ethylhexyl) hydrogen phosphate (trade name: D2EHPA) and 2-ethylhexyl (2-ethylhexyl)phosphonate (trade name: PC-88A) are preferred.

[0072] 4. Method for producing precursor compound for synthesizing positive electrode material for lithium-ion batteries Furthermore, a precursor compound for synthesizing a positive electrode material for a lithium-ion battery can be produced from the aqueous solution of nickel and cobalt mineral salts produced by the above-described method for producing an aqueous solution of nickel and cobalt mineral salts. The aqueous solution of nickel and cobalt mineral salts is an aqueous solution obtained by acid leaching an alloy powder having the above-described properties, and is an aqueous solution in which the copper content is effectively reduced. It is also an aqueous solution containing nickel and cobalt at high concentrations. Therefore, by producing a precursor compound for a positive electrode material using the aqueous solution of nickel and cobalt mineral salts, a precursor compound containing almost no impurities such as copper can be obtained.

[0073] Specifically, the method for producing a precursor compound for synthesizing a positive electrode material for a lithium-ion battery includes the steps of: carrying out a method for producing an aqueous solution of nickel and cobalt mineral salts on an alloy powder containing nickel, cobalt, and copper, thereby producing an aqueous solution of nickel and cobalt mineral salts; purifying the obtained aqueous solution of mineral salts to obtain an aqueous solution containing purified nickel and cobalt; and adding hydroxides or carbonates to the aqueous solution containing purified nickel and cobalt, thereby precipitating nickel and cobalt as hydroxides or carbonates, and obtaining a solid suitable for synthesizing a positive electrode material for a lithium-ion battery.

[0074] [Step of Producing an Aqueous Solution of Nickel and Cobalt Mineral Acid Salts] The aqueous solution of nickel and cobalt mineral salts can be produced by carrying out the method for producing an aqueous solution of nickel and cobalt mineral salts described above in detail, and therefore, a detailed description thereof will be omitted here.

[0075] [Step of purifying the mineral acid salt aqueous solution] As described above, in the step of purifying the obtained aqueous solution of mineral acid salt, treatments such as solution purification and solvent extraction can be carried out alone or in combination depending on the types of impurities contained in the aqueous solution of mineral acid salt, thereby obtaining a purified aqueous solution in which the impurities are reduced and nickel and cobalt are concentrated.

[0076] [Process for obtaining a solid suitable for synthesizing positive electrode materials for lithium-ion batteries] Subsequently, hydroxides or carbonates are added to the aqueous solution containing the purified nickel and cobalt, thereby precipitating the nickel and cobalt as hydroxides or carbonates. By this treatment, impurities remaining in the aqueous solution can be removed.

[0077] The nickel and cobalt hydroxides or carbonates thus deposited can be effectively used as raw materials for precursor compounds for synthesizing a positive electrode material for a lithium ion battery having a desired composition.

[0078] Specifically, for example, by adding manganese sulfate or the like to the precipitated hydroxide or carbonate of nickel and cobalt, a precursor compound for synthesizing a ternary cathode material (NMC) containing nickel, manganese, and cobalt as the main components can be obtained. [Example]

[0079] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to the following examples in any way.

[0080] [Preparation of alloy powder] Using waste battery materials, including lithium-ion secondary battery scrap, as raw materials, atomization was performed using a water atomization method to produce alloy powder containing nickel, cobalt, and copper. In the atomization process, a molten alloy containing nickel, cobalt, and copper, obtained through a dry smelting process of the raw materials, was poured into a small crucible with holes in the bottom, and high-pressure water was sprayed onto the molten alloy that flowed out from the holes, causing it to scatter and solidify, and then the alloy powder (atomized powder) was obtained by sieving.

[0081] Furthermore, in the atomization treatment, the raw materials to be subjected to the pyrometallurgical treatment, the conditions for the pyrometallurgical treatment, and the conditions for the water atomization method were adjusted in various ways so that the copper content and specific surface area of ​​the obtained alloy powder would be the values ​​shown in Table 1 below.

[0082] [Acid leaching treatment for alloy powder] Next, 25.0 g of the produced alloy powder was sampled in each example and comparative example. Sulfur was prepared as a sulfurizing agent in an amount equivalent to 1 to form copper sulfide relative to the amount of copper contained in the alloy powder. The sulfur was placed in a 500 ml separable flask equipped with a baffle and slurried with 250 ml of sulfuric acid solution at pH 1.0.

[0083] In each example and comparative example, the prepared slurry was stirred at a rotation speed of 300 rpm, air was blown in as an oxidizing agent at a rate of 250 ml / min, and while maintaining the liquid temperature at 60°C or higher, 70% sulfuric acid was added to adjust the pH to 1.0, thereby carrying out a leaching treatment to leach nickel and cobalt from the alloy powder.

[0084] The alloy powder conditions, leaching time, and measurement results of the nickel and cobalt concentrations in the resulting leachates used in each example and comparative example are shown in Table 1. The nickel and cobalt concentrations were measured using an ICP-5100 optical emission spectrometer manufactured by Agilent.

[0085] Fig. 1 is a graph showing the relationship between the specific surface area of ​​the alloy powder and the leaching time, with the plots in the graph showing, from left to right, the results of Comparative Example 1, Example 1, Example 2, Example 3, and Example 4. Fig. 2 is a graph showing the relationship between the specific surface area of ​​the alloy powder and the copper content, with the "○" plots in the graph showing, from left to right, the results of Example 6, Example 1, and Example 8, and the "△" plots in the graph showing, from left to right, the results of Comparative Example 3, Example 2, Example 5, and Comparative Example 2.

[0086] [Table 1]

[0087] As can be seen from the results of the examples shown in Table 1, in alloy powders with a copper content of 25 mass % to 45 mass %, the specific surface area was 0.07 m 2 / g or more, it was possible to obtain a nickel and cobalt sulfate aqueous solution containing high concentrations of nickel and cobalt while shortening the leaching time.

[0088] On the other hand, in Comparative Example 1, the specific surface area was 0.05 m 2 / g alloy powder, nickel and cobalt could be effectively leached, but the leaching time was long. In Comparative Example 2, the copper content was high, so the leaching time was relatively short, but the concentrations of nickel and cobalt in the obtained nickel and cobalt sulfate aqueous solution were low. In Comparative Example 3, the copper content was low, so although an aqueous nickel and cobalt sulfate solution containing high concentrations of nickel and cobalt was obtained, the leaching time was relatively long.

Claims

1. An alloy powder containing at least nickel, cobalt, and copper, The copper content is 25% by mass to 45% by mass, and the specific surface area is 0.07 m ２ / g or more.

2. The total content of nickel and cobalt is 30% by mass or more. The alloy powder of claim 1.

3. 10. A method for producing the alloy powder of claim 1, comprising: providing an alloy containing at least nickel, cobalt, and copper, the copper content being between 25% and 45% by weight; The prepared alloy was subjected to atomization to obtain a powder with a specific surface area of ​​0.07 m ２ / g or more of alloy powder; A method for producing an alloy powder, comprising:

4. The alloy is obtained through a pyrometallurgical process including a reduction melting treatment of raw materials including waste battery materials. The method for producing the alloy powder according to claim 3.

5. 10. A method for producing an aqueous solution of nickel and cobalt mineral salts using the alloy powder of claim 1, comprising the steps of: leaching nickel and cobalt from the alloy powder with a mineral acid to produce an aqueous solution of mineral acid salts of nickel and cobalt; A method for producing aqueous solutions of nickel and cobalt mineral salts.

6. leaching nickel and cobalt from the alloy powder by immersing the alloy powder in a mineral acid solution in the presence of one or more sulfiding agents selected from hydrogen sulfide, solid sulfur, sodium hydrogen sulfide, and sodium sulfide; 6. The method for producing an aqueous solution of nickel and cobalt mineral salts according to claim 5.

7. the acid is sulfuric acid; producing an aqueous solution of nickel and cobalt sulfates; 7. The method for producing an aqueous solution of nickel and cobalt mineral salts according to claim 5 or 6.

8. 1. A method for producing nickel sulfate and cobalt sulfate, comprising:

6. The method of claim 5, wherein sulfuric acid is used as the mineral acid to obtain an aqueous solution of nickel and cobalt sulfates; a step of subjecting the aqueous sulfate solution to a solvent extraction treatment to extract and remove impurities, thereby obtaining a purified mixed aqueous solution of nickel sulfate and cobalt sulfate; A method for producing nickel sulfate and cobalt sulfate, comprising:

9. The method further comprises a step of crystallizing the obtained mixed aqueous solution to obtain a mixed salt of nickel sulfate and cobalt sulfate. The method for producing nickel sulfate and cobalt sulfate according to claim 8.

10. 1. A method for producing a precursor compound for the synthesis of a positive electrode material for a lithium ion battery, comprising: Implementing the method of claim 5 to produce an aqueous solution of nickel and cobalt mineral salts; purifying the aqueous solution of nickel and cobalt mineral salts to obtain an aqueous solution containing purified nickel and cobalt; adding hydroxides or carbonates to an aqueous solution containing the purified nickel and cobalt to precipitate nickel and cobalt as hydroxides or carbonates, thereby obtaining a solid suitable for synthesizing the lithium-ion battery positive electrode material; A method comprising:

Images