Method for producing nickel-cobalt alloy

Abstract

The purpose of the present invention is to efficiently produce a valuable-metal-containing alloy, while suppressing excessive energy consumption, from a raw material including a waste battery material that contains iron, lithium, a rare earth element, nickel, and cobalt.　The present invention is a method for producing an alloy of nickel and cobalt from a raw material including a waste battery material that contains nickel and cobalt, the method comprising: a preparation step for preparing a raw material including a waste battery material that contains at least iron, lithium, a rare earth element, nickel, and cobalt; a reduction melting step for subjecting the raw material to a reduction melting treatment to obtain a reduced product that contains slag and a nickel-cobalt alloy; and a slag separation step for separating the slag from the reduced product and recovering the nickel-cobalt alloy. In the preparation step, the mass ratio of Li to the rare earth element in the raw material is 0.3 or greater, and in the reduction melting step, the rare earth element content of the resulting slag is 0.3-11 mass%.

Description

Manufacturing method for nickel-cobalt alloy

[0001] The present invention relates to a method for producing a nickel-cobalt alloy from raw materials including waste battery materials.

[0002] In recent years, lithium-ion rechargeable batteries have gained prominence as lightweight and high-output batteries, and their use is expanding in various applications, including automobiles and smartphones. However, the manufacture of these lithium-ion batteries relies on rare metals, and these rare metals may be depleted in the future. Therefore, establishing recycling technologies for these rare metals is a pressing need. For example, nickel and cobalt, primarily used in cathode materials, are expensive metals and are treated as valuable metals, requiring technologies for more efficient reuse.

[0003] As a recycling method, a dry smelting process has been proposed in which used lithium-ion batteries generated in accordance with the product lifecycle of automobiles and other products, as well as lithium-ion batteries discarded as defective products during manufacturing, are completely melted in a high-temperature furnace. The dry smelting process is a method in which crushed waste battery materials are melted and separated and recovered from valuable metals that are the target of recovery, such as cobalt and nickel, and low value-added metals such as iron and aluminum, by utilizing the difference in oxygen affinity between them. In this method, low value-added metals are oxidized as much as possible to form slag, while the oxidation of valuable metals is minimized as much as possible to recover them as alloys.

[0004] For example, Patent Document 1 discloses a method for recovering valuable metals containing nickel and cobalt from waste batteries containing nickel and cobalt. Specifically, the method comprises a melting step of melting the waste batteries to obtain a molten material, an oxidation step of oxidizing the waste batteries by applying oxidation to the molten material or to the waste batteries before the melting step, and a slag separation step of separating slag from the molten material to recover an alloy containing valuable metals. The proposed process involves adding calcium oxide in the melting step to lower the liquidus temperature of the slag in order to recover the valuable metals.

[0005] In the method of recovering valuable metals as alloys from waste battery materials, the raw materials containing these materials may include not only the aforementioned waste lithium-ion batteries, but also other types of waste batteries such as used nickel-metal hydride batteries, as well as electronic components containing valuable metals. This makes it possible to efficiently recover and reuse valuable metals from various types of waste battery materials.

[0006] However, if various waste battery materials are introduced into the processing step together in an uncrushed or unsorted state, the content of iron, for example, in the raw materials increases. This iron is then distributed into the resulting alloy, increasing the impurity content in the alloy, which can make it difficult to achieve a high recovery rate for valuable metals such as cobalt.

[0007] Furthermore, waste battery materials used in the recycling process of valuable metals, including nickel-metal hydride batteries, sometimes contain relatively large amounts of rare earth elements such as lanthanum, cerium, neodymium, praseodymium, and yttrium. When raw materials containing such rare earth elements are subjected to heating and melting treatment, these rare earth elements are distributed into the slag as oxides, but the resulting slag has a high melting point, requiring excessive energy input for the heating and melting treatment. In addition, there is the problem of loss of valuable metals such as cobalt.

[0008] Patent No. 6819827

[0009] This invention was proposed in view of the circumstances described above, and aims to provide a method for efficiently producing alloys containing valuable metals from raw materials, including waste battery materials containing at least iron, lithium, rare earth elements, nickel, and cobalt, while suppressing excessive energy consumption.

[0010] The inventors of this invention conducted extensive research to solve the above-mentioned problems. As a result, they discovered that controlling the composition of the slag, including the rare earth elements, is important, and that by adjusting the balance with the metal elements in the raw materials as the amount of rare earth elements in the raw materials increases, and thereby controlling the slag melting point, it is possible to efficiently produce alloys containing valuable metals. This led to the completion of the present invention.

[0011] (1) The first aspect of the present invention is a method for producing a nickel-cobalt alloy from raw materials including waste battery material containing nickel (Ni) and cobalt (Co), comprising: a preparation step of preparing raw materials including waste battery material containing at least iron (Fe), lithium (Li), rare earth elements, nickel, and cobalt; a reduction melting step of subjecting the raw materials to a reduction melting treatment to obtain a reduced product including slag and a nickel-cobalt alloy containing the nickel and cobalt; and a slag separation step of separating the slag from the reduced product to recover the nickel-cobalt alloy, wherein in the preparation step the mass ratio of Li / rare earth elements in the raw materials is 0.3 or more, and in the reduction melting step the rare earth element content in the obtained slag is 0.3 to 11% by mass.

[0012] (2) The second invention of the present invention is a method for producing a nickel-cobalt alloy, wherein, in the first invention, the rare earth element is an element selected from lanthanum (La), cerium (Ce), neodymium (Nd), praseodymium (Pr), and yttrium (Y).

[0013] (3) The third invention of the present invention is a method for producing a nickel-cobalt alloy in which, in the preparation step of the first or second invention, the mass ratio of Fe / Co in the raw material is 0.0 to 0.7.

[0014] (4) The fourth invention of the present invention is that in any of the first to third inventions, in either the preparation step or the reduction melting step, a calcium (Ca) compound is added to the raw material and / or processed product, and in the reduction melting step, (Li) in the resulting slag ２ This is a method for producing nickel-cobalt alloys, wherein the mass ratio expressed as (O + CaO) / rare earth oxide is between 3.0 and 80.0.

[0015] (5) The fifth invention of the present invention is that in the fourth invention, the slag is 0.45 ≤ (2 × Li ２ O+CaO) / (3x rare earth oxide + Al ２ O ３ This is a method for manufacturing a nickel-cobalt alloy that satisfies ≤ 2.0.

[0016] (6) The sixth invention of the present invention is a method for producing a nickel-cobalt alloy in which, in any of the first to fifth inventions, the mass ratio expressed as Cu / (Ni+Co+Cu) in the raw materials is 0.25 to 0.70 in the preparation step.

[0017] (7) The seventh invention of the present invention is a method for producing nickel sulfate and / or cobalt sulfate from raw materials including waste battery material containing nickel (Ni) and cobalt (Co), comprising: an alloy manufacturing step of producing a nickel-cobalt alloy by the method of the first invention; and a wet processing step of producing nickel sulfate and / or cobalt sulfate from the nickel-cobalt alloy through a wet processing process including leaching with sulfuric acid.

[0018] (8) The eighth invention of the present invention is a method for producing nickel sulfate and cobalt sulfate, wherein, in the seventh invention, a mixed aqueous solution of nickel sulfate and cobalt sulfate is produced by going through the wet treatment process in the wet treatment step.

[0019] (9) The ninth invention of the present invention is a method for producing a precursor compound for the synthesis of a positive electrode material for a lithium-ion battery, comprising: an alloy production step of producing a nickel-cobalt alloy by the method of the first invention; a step of producing an aqueous solution of nickel and cobalt salt from the nickel-cobalt alloy through a wet treatment process including leaching with acid; a step of purifying the aqueous solution of salt to obtain an aqueous solution containing purified nickel and cobalt; and a step of adding hydroxide or carbonate to the aqueous solution containing purified nickel and cobalt to precipitate nickel and cobalt as hydroxide or carbonite to obtain a solid suitable for the synthesis of the positive electrode material for a lithium-ion battery.

[0020] According to the present invention, it is possible to provide a method for efficiently producing alloys containing valuable metals from raw materials, including waste battery materials containing at least iron, lithium, rare earth elements, nickel, and cobalt, while suppressing excessive energy consumption.

[0021] The following describes specific embodiments of the present invention (hereinafter referred to as "these embodiments") in detail. However, the present invention is not limited in any way to the following embodiments, and can be implemented with appropriate modifications without altering the gist of the invention. In this specification, the notation "X to Y" (where X and Y are arbitrary numerical values) means "X or more and Y or less".

[0022] ≪1. Method for Manufacturing Alloys Containing Valuable Metals≫ The method for manufacturing valuable metals according to this embodiment is a method for manufacturing a nickel-cobalt alloy (hereinafter also simply referred to as "alloy") from raw materials containing at least nickel (Ni) and cobalt (Co) as valuable metals. In particular, this method is a method that enables the efficient manufacture of alloys containing valuable metals, targeting raw materials including waste battery materials containing iron (Fe), lithium (Li), rare earth elements, nickel, and cobalt.

[0023] Furthermore, if copper (Cu) is also included as a valuable metal in the raw materials, an alloy containing even more copper, namely a nickel-cobalt-copper alloy, can be manufactured.

[0024] Specifically, the method according to this embodiment includes a preparation step of preparing raw materials including waste battery material containing at least iron, lithium, rare earth elements, nickel, and cobalt; a reduction melting step of subjecting the raw materials to a reduction melting treatment to obtain a reduced product including slag and a nickel-cobalt alloy containing nickel and cobalt; and a slag separation step of separating the slag from the reduced product and recovering the nickel-cobalt alloy.

[0025] Furthermore, the method according to this embodiment is characterized in that, in the preparation step, the mass ratio of Li / rare earth elements in the raw material is set to 0.3 or more, and in the reduction melting step, the rare earth element content in the resulting slag is set to 0.3 to 11% by mass.

[0026] Furthermore, in this method, it is preferable to add a calcium (Ca) compound in either the preparation step or the reduction melting step, or both, thereby reducing the amount of (Li) in the resulting slag during the reduction melting step. ２The mass ratio expressed as (O + CaO) / rare earth oxide should be between 3.0 and 80.0.

[0027] Furthermore, the slag obtained in the reduction melting process is 0.45 ≤ (2 × Li ２ O+CaO) / (3x rare earth oxide + Al ２ O ３ It is preferable that the relationship ) ≤ 2.0 is satisfied.

[0028] [Preparation Process] In the preparation process, the raw materials to be processed are prepared. The raw materials are those to be processed for the production of alloys containing valuable metals, and are subjected to processing in the reduction melting process described later. As mentioned above, the raw materials to be prepared contain at least iron, lithium, and rare earth elements, as well as waste battery material containing the valuable metals nickel and cobalt. The raw materials may also contain waste battery material containing copper as a further valuable metal. In the raw materials, these components (Fe, Li, rare earth elements, Ni, Co, etc.) may be contained in the form of metals or in the form of compounds such as oxides. In addition, the raw materials may contain inorganic and organic components other than these components.

[0029] The rare earth elements included in the raw materials are not particularly limited, but are, for example, elements selected from lanthanum (La), cerium (Ce), neodymium (Nd), praseodymium (Pr), and yttrium (Y). These rare earth elements are included in batteries, including nickel-metal hydride batteries, which will be described later, and are also included as unavoidable impurities in waste battery materials. These rare earth elements are particularly responsible for raising the melting point of the slag obtained by reducing and melting the raw materials.

[0030] The waste battery materials that make up the raw materials are not particularly limited in scope and include used lithium-ion batteries, nickel-metal hydride batteries, and other waste batteries, as well as scrap batteries, positive electrode materials, and negative electrode materials that are defective products generated during the manufacturing process of these batteries. In addition to these waste batteries, the waste battery materials may also include dielectric materials containing valuable metals, magnetic materials, etc.

[0031] Waste battery materials generally contain valuable metals such as nickel, cobalt, and copper. In addition to lithium, they also contain metals with low added value, such as iron and aluminum (Al). In particular, nickel-metal hydride batteries contain relatively more rare earth elements than other waste batteries. Therefore, the method according to this embodiment is a particularly suitable method when using waste battery materials containing nickel-metal hydride batteries as raw materials.

[0032] Note that the form of the waste battery material is not limited as long as it is suitable for the treatment in the reduction melting process described later. For example, in the preparation process, the raw material may be subjected to a pulverization treatment or the like to make it in a form suitable for the treatment. Also, in the preparation process, the raw material may be subjected to treatments such as heat treatment and separation treatment to remove unnecessary components such as moisture and organic substances.

[0033] In the method according to this embodiment, in the preparation process, the mass ratio of lithium (Li / rare earth element) to the rare earth element in the raw material is 0.3 or more. Also, the mass ratio of Li / rare earth element is preferably 0.5 or more, and more preferably 1.0 or more.

[0034] Here, the lithium and rare earth elements contained in the raw material are distributed as oxides in the slag through the treatment in the reduction melting process described later. At this time, lithium oxide (Li ２ O) contributes to lowering the melting point of the obtained slag. On the other hand, rare earth oxides contribute to increasing the melting point of the obtained slag. When the melting point of the slag obtained by the reduction melting treatment becomes high, it is necessary to input excessive energy to heat and melt it in that treatment, and the separation of valuable metals such as cobalt from the slag becomes insufficient, resulting in a recovery loss of valuable metals.

[0035] In this regard, in the method according to this embodiment, by adjusting the mass ratio of Li / rare earth element in the raw material to 0.3 or more in the preparation process, it is possible to suppress the melting point of the slag obtained by subjecting the raw material to the reduction melting treatment from becoming high, and to suppress the consumption of excessive energy. Also, it is possible to prevent poor separation of valuable metals such as cobalt from the slag.

[0036] In addition, the upper limit value of the mass ratio of Li / rare earth elements in the raw material is not particularly limited, but for example, it is preferably 30.0 or less.

[0037] Further, in the preparation step, it is preferable that the mass ratio of iron (Fe / Co) to cobalt in the raw material is 0.0 to 0.7. By using the raw material with the adjusted Fe / Co mass ratio in this way, it is possible to suppress the distribution of iron, which is an impurity, into the alloy and the decrease in the purity of valuable metals in the alloy. In addition, the degree of oxidation in the reduction melting treatment can be suppressed, the distribution of cobalt into the slag can be suppressed, and the decrease in the recovery rate of cobalt, which is a valuable metal, can be suppressed.

[0038] Specifically, by setting the mass ratio of Fe / Co in the raw material to 0.0 to 0.7 in the preparation step, the cobalt content in the slag obtained by subjecting the raw material to reduction melting treatment can be set to 0.1 to 1% by mass, and the iron content in the obtained alloy can be set to 0 to 6% by mass.

[0039] Further, in the preparation step, a waste battery material containing copper, which is a valuable metal, can be used. At this time, regarding nickel, cobalt, and copper, which are valuable metals in the raw material, the mass ratio represented by Cu / (Ni + Co + Cu) is preferably 0.25 to 0.70. By using the raw material with the mass ratio of Cu / (Ni + Co + Cu) adjusted within such a range, it is possible to suppress the increase in the melting point of the alloy (metal) obtained by subjecting the raw material to reduction melting treatment and facilitate the separation from the slag. As a result, it is possible to more efficiently suppress the decrease in the recovery rate of valuable metals.

[0040] The raw material composition in the preparation step can be easily controlled by adjusting the combination of the types of waste battery materials to be treated, the treatment amount, and the like.

[0041] In the preparation step, a calcium (Ca) compound can be added to the raw material. The calcium compound acts as a flux, and the calcium oxide contained in the resulting slag contributes to lowering the melting point of the slag. More details will be described later. In the method according to this embodiment, a calcium compound is added to the raw material and / or the processed product in either the preparation step or the reduction melting step, or both.

[0042] [Reduction Melting Process] In the reduction melting process, the prepared raw materials are charged into a melting furnace, for example, and subjected to a reduction melting treatment to obtain a reduced product containing slag and a nickel-cobalt alloy containing nickel and cobalt.

[0043] As described above, the reduction melting process is a treatment that reduces raw materials by heating them and melting them. The purpose of this treatment is to utilize the difference in oxygen affinity to oxide low-value metals (Fe, Al, etc.) and rare earth elements contained in the raw materials, while reducing and melting valuable metals (Ni, Co, etc.) to recover them as an integrated alloy. After the reduction melting process, a molten alloy is obtained. In this way, the reduction melting process makes it possible to separate the components containing valuable metals (alloy) from other components (slag) in the reduced material.

[0044] In the method according to this embodiment, in the reduction melting step, the raw material prepared in the preparation step, having a Li / rare earth element mass ratio of 0.3 or more, is subjected to reduction melting treatment so that the rare earth element content in the resulting slag is 0.3 to 11% by mass.

[0045] This suppresses the high melting point of the slag obtained during the reduction melting process, thereby reducing excessive energy consumption. Furthermore, it prevents insufficient separation of valuable metals such as cobalt from the slag, thus preventing a decrease in the recovery rate of alloys containing valuable metals.

[0046] Furthermore, as described above, by adjusting the Fe / Co mass ratio in the raw materials prepared in the preparation process to preferably be 0.0 to 0.7, the distribution of cobalt, a valuable metal, into the slag obtained by reducing and melting the raw materials can be suppressed, and the cobalt content in the slag can be reduced to 0.1 to 1 mass%. In addition, the distribution of iron, an impurity, into the resulting alloy can be suppressed, and the iron content in the alloy can be reduced to 0 to 6 mass%.

[0047] In the reduction melting process, calcium (Ca) compounds can be added to the treated material. Here, "treated material" includes not only the material undergoing reduction melting treatment on the raw material, but also the raw material itself before being charged into a melting furnace and heated. In other words, the timing of adding calcium compounds in the reduction melting process is not particularly limited.

[0048] Calcium compounds act as fluxes, and the calcium oxides contained in the resulting slag contribute to lowering the melting point of the slag. The calcium compounds added are not particularly limited, but include calcium oxide (CaO) and calcium carbonate (CaCO3). ３ Examples include the following. In the method according to this embodiment, a calcium compound may be added to the raw material and / or the processed product in either the preparation step or the reduction melting step, or both.

[0049] Thus, by adding a calcium compound to the raw material and / or processed product in either the preparation step or the reduction melting step, the (Li) in the resulting slag is reduced in the reduction melting step. ２ It is preferable that the mass ratio expressed as (O + CaO) / rare earth oxide be between 3.0 and 80.0. By processing the slag to produce a slag with such a composition, the rise in the melting point of the slag can be suppressed more efficiently, and excessive energy consumption can be reduced.

[0050] Furthermore, a higher calcium content in the slag makes it easier to remove phosphorus from the raw material if it is present. This is because phosphorus becomes an acidic oxide when oxidized, while calcium becomes a basic oxide when oxidized. Therefore, the higher the calcium content in the resulting slag, the more basic the slag composition becomes, and as a result, it becomes easier to incorporate and remove phosphorus from the slag.

[0051] Here, the slag obtained after the reduction melting treatment is 0.45 ≤ (2 × Li ２ O+CaO) / (3x rare earth oxide + Al ２ O ３ It is preferable that the condition ) ≤ 2.0 is satisfied.

[0052] As described above, in the slag obtained by the reduction melting treatment, lithium oxide (Li ２ O) contributes to lowering the slag melting point, while rare earth oxides contribute to raising the slag melting point. Calcium oxide (CaO) contributes to lowering the slag melting point, while aluminum oxide (Al) contributes to raising the slag melting point. ２ O ３ This contributes to raising the slag melting point. Therefore, by processing the material to obtain slag with the above-mentioned composition, the increase in the slag melting point can be suppressed more efficiently. In addition, poor separation of valuable metals such as cobalt from the slag can be prevented, thereby suppressing a decrease in the recovery rate of alloys containing valuable metals.

[0053] The composition of the slag can be easily controlled by adjusting the composition of the raw materials and the amount of flux added to the raw materials. In particular, in the method according to this embodiment, slag with the above-described composition can be obtained by adjusting the mass ratio of Li / rare earth elements in the raw materials to 0.3 or more in the preparation step. It is also preferable to adjust the aluminum content in the raw materials in the preparation step as appropriate. Furthermore, it is preferable to adjust the amount of calcium compound added in either the preparation step or the reduction melting step, or both.

[0054] In the reduction melting process, it is preferable to introduce a reducing agent. As the reducing agent, carbon and / or carbon monoxide can be used. Carbon has the ability to easily reduce the valuable metal to be recovered. For example, 1 mole of carbon can reduce 2 moles of valuable metal oxide (e.g., cobalt oxide, nickel oxide). Furthermore, reduction methods using carbon or carbon monoxide are extremely safer than methods using metal reducing agents, such as the thermite reaction method using aluminum. As carbon, artificial graphite and / or natural graphite can be used. In addition, coal or coke can be used if there is no risk of impurity contamination.

[0055] In the reduction melting treatment, although not particularly limited, it is preferable to set the heating temperature to 1400°C or higher and 1600°C or lower. It is even more preferable to set the heating temperature to 1500°C or higher and 1600°C or lower. If the heating temperature exceeds 1600°C, thermal energy will be wasted, and the refractory material will be consumed rapidly, which may reduce productivity. On the other hand, if the heating temperature is below 1400°C, the separation of the slag and the alloy will deteriorate, which may reduce the recovery rate of the alloy containing valuable metals.

[0056] Furthermore, oxidation treatment may be performed concurrently with the reduction melting process. However, if an oxidation roasting process, described later, is provided and the oxidation roasting process is performed prior to the reduction melting process, it is not necessary to perform oxidation treatment during the reduction melting process. Performing oxidation treatment concurrently with the reduction melting process allows for more precise control of the degree of oxidation. One method for performing oxidation treatment is to blow an oxidizing agent such as air, pure oxygen, or oxygen-enriched gas into the material being treated during the reduction melting process. Specifically, oxidation treatment is performed by inserting a metal tube (lance) into the material and blowing in the oxidizing agent by bubbling.

[0057] [Oxidative Roasting Process] In the method according to this embodiment, if necessary, an oxidative roasting process may be further provided prior to the reduction melting treatment, in which the raw material is oxidatively roasted to obtain an oxidative roasted product.

[0058] Oxidative roasting is a process in which raw materials are oxidized and roasted to produce oxidative roasted products. Even if carbon is present in the raw materials, this process oxidizes and removes the carbon, promoting the integration of valuable metals into the alloy during the reductive melting process. Specifically, in the reductive melting process, valuable metals are reduced to localized molten fine particles. However, the carbon contained in the charge acts as a physical obstacle to the aggregation of these metal-containing fine particles, hindering the aggregation and integration of the particles and the resulting separation of the alloy from the slag, which can reduce the recovery rate of valuable metals. In this respect, by subjecting the raw materials to oxidative roasting, carbon in the raw materials can be effectively removed, making it possible to produce alloys containing valuable metals with high purity.

[0059] Generally, oxidation occurs in the order of Al > Li > C > Mn > P > Fe > Co > Ni > Cu. Therefore, it is preferable to perform the oxidation roasting treatment at a level where the oxidation is kept to such an extent that the valuable metal cobalt is not oxidized and distributed into the slag.

[0060] In oxidative roasting, it is preferable to introduce an appropriate amount of oxidizing agent to adjust the degree of oxidation. In particular, raw materials containing waste battery materials may contain metals such as aluminum and iron as outer casing materials, and aluminum foil and carbon materials as positive and negative electrode materials. Therefore, by introducing an oxidizing agent to adjust the degree of oxidation, the degree of oxidation can be efficiently adjusted to an appropriate range.

[0061] The oxidizing agent is not particularly limited as long as it can oxidize carbon or low-value metals, but air, pure oxygen, oxygen-enriched gas, etc., which are easy to handle, are preferred. The amount of oxidizing agent to be introduced should be approximately 1.15 to 1.25 times the amount (chemical equivalent) required for the oxidation of each substance to be subjected to the oxidative roasting treatment.

[0062] The heating temperature for the oxidative roasting process is not particularly limited, but it is preferably 700°C to 1100°C, and more preferably 800°C to 1000°C. By heating to 700°C or higher, the carbon oxidation efficiency can be further increased, and the oxidation time can be shortened. Also, by heating to 1100°C or lower, the thermal energy cost can be suppressed, and the efficiency of oxidative roasting can be increased.

[0063] [Slag Separation Process] In the slag separation process, slag is separated from the reduced material obtained by the reduction melting process, and the alloy containing valuable metals is recovered. The slag and the alloy have different specific gravities, and since the slag has a lower specific gravity than the alloy, it accumulates on top of the alloy. Therefore, efficient separation and recovery can be achieved by specific gravity separation.

[0064] Furthermore, after separating the slag from the reduced material in the slag separation process and recovering the alloy, a sulfidation process may be included to sulfidize the obtained alloy, and a pulverization process may be included to pulverize the mixture of sulfides and alloy obtained in the sulfidation process. In addition, a wet smelting process may be performed on the alloy obtained through such a dry smelting process. The wet smelting process can remove impurities and separate and purify valuable metals (Ni, Co, etc.) for recovery.

[0065] ≪2. Method for Producing Nickel Sulfate and Cobalt Sulfate≫ According to the nickel-cobalt alloy production method described above, nickel-cobalt alloys containing the valuable metals nickel and cobalt can be efficiently produced from waste battery materials. Then, by using the nickel-cobalt alloy produced in this way, nickel sulfate and cobalt sulfate containing high concentrations of nickel and cobalt can be produced. Therefore, the method for producing nickel sulfate and cobalt sulfate can be defined as follows.

[0066] In other words, the method for producing nickel sulfate and cobalt sulfate is a method for producing nickel sulfate and cobalt sulfate from raw materials including waste battery material containing nickel and cobalt, comprising: an alloy production step of producing a nickel-cobalt alloy by performing the above-described method for producing a nickel-cobalt alloy; and a wet treatment step of producing nickel sulfate and cobalt sulfate from the produced nickel-cobalt alloy through a wet treatment process including leaching with sulfuric acid.

[0067] [Alloy Manufacturing Process] The alloy manufacturing process is the process for producing nickel-cobalt alloys. These alloys can be manufactured by using raw materials, including waste battery materials containing nickel and cobalt, and carrying out the method detailed above. This allows for the efficient production of nickel-cobalt alloys containing the valuable metals nickel and cobalt from waste battery materials. Therefore, a detailed explanation is omitted here.

[0068] [Wet Treatment Process for Producing Nickel Sulfate and Cobalt Sulfate] The wet treatment process includes a process in which a nickel-cobalt alloy obtained from the alloy manufacturing process is subjected to a wet treatment with sulfuric acid to obtain aqueous solutions of nickel and cobalt sulfates. Note that "nickel sulfate and cobalt sulfate" includes not only nickel sulfate and cobalt sulfate in solid form, but also aqueous solutions of nickel and cobalt sulfates, as well as mixed aqueous solutions of nickel sulfate and cobalt sulfate.

[0069] (Leaching Treatment) In the leaching treatment, the nickel-cobalt alloy is brought into contact with a mineral acid solution containing sulfuric acid to leach nickel and cobalt from the nickel-cobalt alloy into the sulfuric acid solution. If the nickel-cobalt alloy contains copper, the leaching treatment is performed under conditions in which a sulfidating agent is present. In leaching treatment under conditions in which a sulfidating agent is present, the coexisting sulfidating agent can precipitate the copper leached from the alloy as solid copper sulfide, while the leached nickel and cobalt remain in the leaching solution. This effectively separates copper from nickel and cobalt.

[0070] In the leaching treatment, a mineral acid solution containing sulfuric acid is used as described above. By leaching nickel and cobalt with sulfuric acid, an aqueous sulfate solution of nickel and cobalt can be obtained. The amount of sulfuric acid should be 1 equivalent or more relative to the total amount of nickel and cobalt contained in the nickel-cobalt alloy, preferably 5 equivalents or more, and more preferably 10 equivalents or more. There is no particular upper limit to the amount of sulfuric acid, but 15 equivalents or less is preferred.

[0071] Furthermore, when leaching is performed in the presence of a sulfidating agent, the amount of sulfidating agent added is not particularly limited, but it is preferable to add at least one equivalent of sulfur relative to the amount of copper contained in the nickel-cobalt alloy.

[0072] Regarding other conditions in the leaching process, it is preferable to conduct preliminary tests to determine appropriate ranges for temperature, time, and slurry concentration obtained by adding sulfuric acid-containing mineral acid to the nickel-cobalt alloy. Furthermore, regarding the reaction in the leaching process, since the oxidation-reduction potential (ORP) rises sharply when the hydrogen-evolving nickel and cobalt leaching is complete, the endpoint of nickel and cobalt leaching can be determined by measuring the ORP value of the resulting leached aqueous solution.

[0073] (Reduction Treatment) Furthermore, the nickel and cobalt sulfate aqueous solution obtained from the leaching treatment described above may be subjected to further reduction treatment using a reducing agent. If the nickel-cobalt alloy being leached contains copper, even after leaching in the presence of a sulfidizing agent, some of the copper may not react with the sulfidizing agent and may be leached out by sulfuric acid, and thus contained in the nickel and cobalt sulfate aqueous solution. Therefore, by performing a reduction treatment on the nickel and cobalt sulfate aqueous solution obtained from the leaching treatment, trace amounts of copper in the aqueous solution can be reduced, generating a precipitate containing copper which can then be removed by solid-liquid separation. This makes it possible to obtain a nickel and cobalt sulfate aqueous solution with a reduced copper content, which is an impurity.

[0074] The method of reduction is not particularly limited. When using a solid or liquid reducing agent, the reducing agent can be added directly to the aqueous solution, and when the reducing agent is a gas, it can be added to the aqueous solution by bubbling. Furthermore, it is preferable to select the optimal range for the amount of reducing agent added and the reaction temperature by conducting tests in advance.

[0075] (Purification treatment of sulfate aqueous solution) The nickel and cobalt sulfate aqueous solution obtained as described above contains nickel and cobalt, but since it is obtained via a nickel-cobalt alloy manufactured from raw materials including waste battery materials, it may contain impurities such as iron, zinc, and phosphorus due to the raw materials. Therefore, the nickel and cobalt sulfate aqueous solution may be subjected to a purification treatment, thereby removing impurities and obtaining a purified aqueous solution. The purified aqueous solution is a sulfate aqueous solution in which nickel and cobalt are concentrated.

[0076] The purification treatment for nickel and cobalt sulfate aqueous solutions is not particularly limited, but examples include purification treatment and solvent extraction treatment. In the purification treatment, depending on the type of impurities contained in the aqueous solution, any of the treatments may be performed individually or in combination of two or more treatments.

[0077] Specifically, examples of purification treatments include oxidation treatment and oxidation-neutralization treatment. For example, in oxidation-neutralization treatment, an oxidizing agent is added to an aqueous solution of nickel and cobalt sulfate to induce an oxidation reaction, and a neutralizing agent is added to control the pH of the solution within a predetermined range, thereby generating a precipitate of impurities such as iron and phosphorus contained in the aqueous solution. In this way, by performing oxidation-neutralization treatment as a purification treatment, impurities can be separated as precipitates, and a purified aqueous solution of nickel and cobalt sulfate can be obtained.

[0078] Furthermore, in the solvent extraction process, impurities contained in the nickel and cobalt sulfate aqueous solution, or the aqueous solution obtained after the purification process, are selectively extracted into an organic solvent to separate and remove the impurities and obtain a purified nickel and cobalt sulfate aqueous solution. Alternatively, nickel and cobalt contained in the nickel and cobalt sulfate aqueous solution may be selectively extracted into an organic solvent, and then back-extracted with sulfuric acid to separate and remove impurities and obtain a purified nickel sulfate aqueous solution and a cobalt sulfate aqueous solution.

[0079] (Process for precipitating nickel sulfate and cobalt sulfate) By precipitating nickel sulfate and cobalt sulfate from aqueous solutions of nickel and cobalt sulfates, nickel sulfate and cobalt sulfate can be obtained in solid form.

[0080] The method for precipitating nickel sulfate and cobalt sulfate is not particularly limited. For example, one method involves using a crystallization apparatus to evaporate the water in an aqueous solution and precipitate crystals of nickel sulfate and cobalt sulfate.

[0081] ≪3. Method for producing precursor compounds for synthesizing positive electrode materials for lithium-ion batteries≫ Furthermore, precursor compounds for synthesizing positive electrode materials for lithium-ion batteries can be produced from nickel-cobalt alloys produced by the nickel-cobalt alloy production method described above.

[0082] Specifically, a method for producing a precursor compound for synthesizing a positive electrode material for lithium-ion batteries includes: an alloy manufacturing step of producing a nickel-cobalt alloy by carrying out the nickel-cobalt alloy manufacturing method described above; a step of producing an aqueous solution of nickel and cobalt salts from the nickel-cobalt alloy through a wet treatment process including acid leaching; a step of purifying the aqueous solution of salts to obtain an aqueous solution containing purified nickel and cobalt; and a step of adding hydroxide or carbonate to the aqueous solution containing purified nickel and cobalt to precipitate nickel and cobalt as hydroxide or carbonite to obtain a solid suitable for synthesizing a positive electrode material for lithium-ion batteries.

[0083] [Process for Manufacturing Nickel-Cobalt Alloys] In the process for manufacturing nickel-cobalt alloys, the nickel-cobalt alloy manufacturing method described in detail above is carried out using raw materials including waste battery materials containing nickel and cobalt. This makes it possible to efficiently manufacture nickel-cobalt alloys containing the valuable metals nickel and cobalt from waste battery materials. Therefore, a detailed explanation is omitted here.

[0084] [Process for producing nickel and cobalt salt solutions] In the process for producing nickel and cobalt salt solutions, a nickel-cobalt alloy is subjected to a wet treatment with a mineral acid to obtain nickel and cobalt salt solutions. For example, if sulfuric acid is used as the mineral acid in the leaching treatment, a nickel and cobalt sulfate solution can be obtained. If hydrochloric acid is used, a nickel and cobalt hydrochloride solution can be obtained. For example, the process for producing a nickel and cobalt sulfate solution using sulfuric acid as the mineral acid has been described in detail above, and a detailed explanation is omitted here.

[0085] [Process for purifying the saline solution] In the process for purifying the saline solution, impurities are removed from the obtained nickel and cobalt saline solution. This reduces the amount of impurities and allows for the production of a purified saline solution in which nickel and cobalt are concentrated. As described above, the purification process can be carried out by performing treatments such as liquid purification and solvent extraction, either individually or in combination of two or more, depending on the type of impurities contained in the saline solution.

[0086] [Process for obtaining a solid suitable for the synthesis of positive electrode material for lithium-ion batteries] Next, hydroxide or carbonate is added to the aqueous solution containing purified nickel and cobalt to precipitate nickel and cobalt as hydroxide or carbonite. Through this process, a solid containing nickel and cobalt can be obtained.

[0087] The nickel and cobalt hydroxides or carbonides thus precipitated can be effectively used as raw materials for precursor compounds to synthesize lithium-ion battery cathode materials of a desired composition.

[0088] Specifically, for example, by adding manganese sulfate or the like to precipitated nickel and cobalt hydroxide or carbonite, a precursor compound for synthesizing a ternary cathode material (NMC) mainly composed of nickel, manganese, and cobalt can be obtained.

[0089] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0090] [Regarding the manufacturing process of nickel-cobalt alloys] In each example and comparative example, a nickel-cobalt alloy was manufactured using raw materials that included waste battery material containing nickel and cobalt, as well as impurities containing rare earth elements.

[0091] (Preparation Process) Used lithium-ion batteries and used nickel-metal hydride batteries were prepared as waste battery materials to constitute the raw materials. In the preparation process, the mass ratio of Li / rare earth elements in the raw materials was adjusted based on the composition of the prepared lithium-ion batteries and nickel-metal hydride batteries, as shown in Table 1 below. In addition, in the preparation process, the mass ratio of Fe / Co and the mass ratio of Cu / (Ni+Co+Cu) for valuable metals in the raw materials were adjusted, as shown in Table 1 below.

[0092] In addition, in the raw material process, by adjusting the combination of waste battery materials, the slag obtained after processing in the reduction melting process is (LiO ２ (2 × Li) / Mass ratio expressed as (2 × Li) ２ O+CaO) / (3x rare earth oxide + Al ２ O ３ The mass ratio expressed as ) was adjusted to produce slag as shown in Table 1 below.

[0093] (Reduction Melting Process) Approximately 20 g of raw materials, including the waste battery material prepared in the preparation process, was placed in a 30 ml crucible, and the raw materials were heated and melted to perform the reduction melting treatment. In the reduction melting treatment, 1 to 5 g of calcium oxide (CaO) and 0 to 1 g of carbon as a reducing agent were added to the material being treated. A small electric furnace was used as the melting furnace.

[0094] (Slag Separation Process) After the reduction melting treatment, the obtained reduced material was separated by specific gravity, with the slag going to the upper layer and the nickel-cobalt alloy to the lower layer. The crucible was then cooled to recover the slag and nickel-cobalt alloy, respectively.

[0095] [Component Analysis of Slag and Alloy] The slag and nickel-cobalt alloy (metal) separated from the reduced material were recovered, cooled, and then pulverized. Component analysis was then performed using X-ray fluorescence. Based on the results of this component analysis, the recovery rates of the valuable metals nickel, cobalt, and copper were calculated as follows: (Valuable Metal Recovery Rate) For example, the recovery rate of the valuable metal (Co) was calculated based on the following formula 1. Nickel and copper were calculated similarly. Valuable Metal Recovery Rate (%) = (Weight of Co in recovered alloy) ÷ (Weight of Co in recovered alloy + Weight of Co in slag) × 100 ... (Formula 1)

[0096] [Results] Table 1 below shows the composition of the raw materials used in each example and comparative example, as well as the composition of the obtained slag, the iron content in the metal, and the recovery rate of valuable metals.

[0097]

[0098] In Examples 1 to 10, which are specific examples of the present invention, the mass ratio of Li / rare earth elements in the raw materials containing waste battery material was adjusted to 0.3 or higher, and the reduction melting treatment was performed using these raw materials. As a result, it was possible to suppress the decrease in the recovery rate of valuable metals and efficiently produce alloys containing those valuable metals.

Claims

1. A method for producing a nickel-cobalt alloy from raw materials including waste battery material containing nickel (Ni) and cobalt (Co), comprising: a preparation step of preparing raw materials including waste battery material containing at least iron (Fe), lithium (Li), rare earth elements, nickel, and cobalt; a reduction melting step of subjecting the raw materials to a reduction melting treatment to obtain a reduced product including slag and a nickel-cobalt alloy containing the nickel and cobalt; and a slag separation step of separating the slag from the reduced product to recover the nickel-cobalt alloy, wherein in the preparation step, the mass ratio of Li / rare earth elements in the raw materials is 0.3 or more, and in the reduction melting step, the rare earth element content in the obtained slag is 0.3 to 11% by mass.

2. The method for producing a nickel-cobalt alloy according to claim 1, wherein the rare earth element is an element selected from lanthanum (La), cerium (Ce), neodymium (Nd), praseodymium (Pr), and yttrium (Y).

3. The method for producing a nickel-cobalt alloy according to claim 1, wherein in the preparation step, the mass ratio of Fe / Co in the raw material is 0.0 to 0.

7.

4. In either the preparation step or the reduction melting step, or both, a calcium (Ca) compound is added to the raw material and / or the processed product, and in the reduction melting step, (Li) is added to the slag obtained. ２ A method for producing a nickel-cobalt alloy according to claim 1, wherein the mass ratio expressed as (O + CaO) / rare earth oxide is 3.0 to 80.

0.

5. The slag is 0.45 ≤ (2 × Li ２ O+CaO) / (3x rare earth oxide + Al ２ O ３ A method for producing a nickel-cobalt alloy according to claim 4, satisfying ) ≤ 2.

0.

6. The method for producing a nickel-cobalt alloy according to claim 1, wherein in the preparation step, the mass ratio expressed as Cu / (Ni+Co+Cu) in the raw materials is 0.25 to 0.

70.

7. A method for producing nickel sulfate and / or cobalt sulfate from raw materials including waste battery materials containing nickel (Ni) and cobalt (Co), comprising: an alloy manufacturing step of producing a nickel-cobalt alloy by the method of claim 1; and a wet treatment step of producing nickel sulfate and / or cobalt sulfate from the nickel-cobalt alloy through a wet treatment process including leaching with sulfuric acid.

8. The method for producing nickel sulfate and / or cobalt sulfate according to claim 7, wherein a mixed aqueous solution of nickel sulfate and cobalt sulfate is produced by going through the wet treatment process in the wet treatment step.

9. A method for producing a precursor compound for the synthesis of a positive electrode material for a lithium-ion battery, comprising: an alloy production step of producing a nickel-cobalt alloy by the method of claim 1; a step of producing an aqueous solution of nickel and cobalt salt from the nickel-cobalt alloy through a wet treatment process including leaching with acid; a step of purifying the aqueous solution of the salt to obtain an aqueous solution containing purified nickel and cobalt; and a step of adding hydroxide or carbonate to the aqueous solution containing purified nickel and cobalt to precipitate nickel and cobalt as hydroxide or carbonite to obtain a solid suitable for the synthesis of the positive electrode material for a lithium-ion battery.

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