Method for producing nickel compound or nickel hydroxide

Abstract

A method for producing a nickel compound, the method including: a step for preparing a starting material metal oxide which contains a first metal containing at least nickel and a second metal; a step for mixing the starting material metal oxide and an aqueous acid solution so as to obtain a first solution that contains ions of the first metal and the second metal by acid leaching; a first generation step for neutralizing the first solution with a first alkali so as to generate a solid content that contains the second metal and a second solution that contains at least ions of the first metal; a step for solid-liquid separating the second solution and the solid content; a second generation step for mixing the second solution and a second alkali that contains at least a metal hydroxide and ammonia so as to generate a nickel compound that contains at least nickel as the first metal and a third solution; and a step for solid-liquid separating the nickel compound and the third solution.

Description

Method for producing nickel compounds or nickel hydroxides Cross-reference of related applications

[0001] This disclosure claims priority rights to Japanese Patent Application No. 2024-189602, filed with the Japan Patent Office on 29 October 2024, and the entirety of the said patent application is incorporated herein by reference.

[0002] This disclosure relates to a method for producing nickel compounds or nickel hydroxides.

[0003] Patent Document 1 proposes a method for recovering valuable metals from battery residue of a lithium-ion battery containing valuable metals, comprising: (a) a step of dispersing the battery residue in water and adding sulfuric acid to obtain a leachate with a pH of 0 to 2; (b) a step of adding sodium hydroxide to the leachate to adjust the pH to 7 to 10 and separating the leachate containing Li and Mn from a precipitate containing hydroxides of other valuable metals; (c) a step of dispersing the precipitate in water and adding sulfuric acid to adjust the pH to 0 to 2 and separating the precipitate containing Cu from the leachate containing other valuable metals; (d) a step of adding an oxidizing agent to the leachate obtained in step (c) and separating the precipitate containing Mn from the leachate containing other valuable metals; and (e) a step of adding sodium hydroxide to the leachate obtained in step (d) to adjust the pH to 4 to 6 and separating the leachate containing Co and Ni from the precipitate containing Fe and Al.

[0004] Patent Document 2 describes a process comprising: a calcination step (S10) for calcining black mass; a pre-extraction step (S20) for separating the calcined black mass obtained from the calcination step (S10) into a lithium (Li) solution and a cake by leaching it with water; and a process for evaporating and concentrating the lithium (Li) solution produced in the pre-extraction step (S20) to obtain lithium carbonate (Li) ２ CO ３A first evaporation and concentration step (S30) for producing crystals; a leaching step (S40) for leaching the cake separated in the pre-extraction step (S20); a first purification step (S50) for removing copper and aluminum from the leaching solution produced in the leaching step (S40); a post-extraction step (S60) for neutralizing the solution from the first purification step (S50) to separate it into a lithium (Li) solution and a cake (NCM cake) containing Ni, Co, and Mn; and lithium carbonate (Li) produced in the first evaporation and concentration step (S30). ２ CO ３ The present invention proposes a method for producing secondary battery material from black mass, comprising: a transfer step of transferring the crystal and the lithium (Li) solution produced by the post-extraction step (S60) to a lithium hydroxide (LiOH) production step.

[0005] Patent Document 3 proposes a method for extracting metals from the black mass of a lithium-ion battery, wherein the black mass contains the anode material and cathode material of the battery, and the cathode material comprises lithium, nickel, and cobalt, and the method comprises (a) one or more pretreatment steps, wherein a fraction of nonmetallic materials is separated from the black mass and the pretreated black mass containing the anode material and cathode material is recovered; (b) one or more leaching steps, wherein an acid leaching step is performed in a sulfuric acid-containing solution by further adding a gas containing sulfur dioxide and molecular oxygen as extractants to the acid leaching step, thereby dissolving the cathode material of the pretreated black mass and recovering a leaching solution containing the dissolved cathode material; and (c) a metal separation step, wherein an initial fraction of metallic materials is separated from the leaching solution and a major fraction containing at least one of cobalt, nickel, and lithium is recovered.

[0006] Patent Document 4 proposes "a method for recovering lithium-ion battery material from black mass, the method comprising: a first step of acid leaching the black mass to produce an acid leached material; and a second step of applying a reducing agent to the acid leached material."

[0007] Patent Document 5 proposes a recycled cathode material characterized by containing lithium, nickel, cobalt, and manganese, aluminum in an amount of 0.3% to 3% by mass, and at least one of copper and iron in an amount of less than 1% by mass.

[0008] Japanese Patent Publication No. 2024-112398, Japanese Patent Publication No. 2024-517044, Japanese Patent Publication No. 2024-516955, Japanese Patent Publication No. 2023-174586, Japanese Patent Publication No. 2023-183355

[0009] Patent documents 1 to 5 have proposed technologies for recycling battery materials. These technologies include a process for generating a coprecipitation by neutralization and a solid-liquid separation process. However, there is a problem in that the coprecipitation obtained by neutralization becomes a fine powder, and the solid-liquid separation takes a long time.

[0010] One aspect of this disclosure relates to a method for producing a nickel compound, comprising: a step of preparing a raw material metal oxide comprising a first metal comprising at least nickel and a second metal comprising at least one selected from the group consisting of magnesium, calcium, iron, silicon, zinc, copper, aluminum, and lithium (preparation step); a step of mixing the raw material metal oxide with an aqueous acid solution to obtain a first solution containing ions of the first and second metals by acid leaching (leaching step); a first production step of neutralizing the first solution with a first alkali to produce a solid component comprising the second metal and a second solution containing at least ions of the first metal; a step of solid-liquid separation of the second solution and the solid component (first solid-liquid separation step); a second production step of mixing the second solution with a second alkali containing at least a metal hydroxide and ammonia to produce a nickel compound comprising at least nickel as the first metal and a third solution; and a step of solid-liquid separation of the nickel compound and the third solution (second solid-liquid separation step).

[0011] According to this disclosure, it is possible to produce nickel compounds with particle sizes suitable for solid-liquid separation. Novel features of the present invention are described in the appended claims, but the present invention, in conjunction with other objects and features of the present invention, will be better understood by the following detailed description in conjunction with the drawings, both in terms of structure and content.

[0012] The embodiments of this disclosure will be described below with examples, but this disclosure is not limited to the examples described below. In the following description, specific numerical values, materials, etc. may be given as examples, but other numerical values, materials, etc. may be applied as long as the effects of this disclosure are obtained. In addition, known components may be applied to components other than those characteristic of this disclosure. In this specification, when "the range of numerical values ​​A to numerical values ​​B" is used, the range includes numerical values ​​A and B.

[0013] In the following explanation, when examples are given for the lower and upper limits of numerical values ​​related to specific physical properties or conditions, any combination of either of the given lower limits and any of the given upper limits is permitted, as long as the lower limit does not exceed the upper limit. When multiple materials are given as examples, unless otherwise specified, one type may be selected and used alone, or two or more types may be used in combination.

[0014] Furthermore, this disclosure encompasses any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims. In other words, any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims, is possible, provided that no technical inconsistency arises.

[0015] <Preparation Step> In a method for producing a nickel compound according to one embodiment of the present disclosure (hereinafter also referred to as "production method (M)"), a raw material metal oxide is used as a starting material, which includes a first metal containing at least nickel and a second metal containing at least one selected from the group consisting of magnesium, calcium, iron, silicon, zinc, copper, aluminum, and lithium. The first metal is the metal to be purified, and the second metal is positioned as an impurity. In addition to nickel, the first metal may further contain at least one selected from the group consisting of cobalt and manganese. The first metal may contain three types: nickel, cobalt, and manganese.

[0016] Typically, black mass can be used as the raw material metal oxide. Since black mass is recovered by incinerating the shredded material of collected used batteries, it contains oxides of various metals. Used batteries include lithium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and dry cell batteries. Black mass usually contains at least 1% by mass of iron, aluminum, and copper as secondary metals.

[0017] Black mass is an oxide containing metallic elements, primarily nickel, and also containing cobalt and other optional metals such as manganese. Therefore, the compound intended for production by manufacturing method (M) is a compound containing at least nickel, such as nickel-cobalt composite compounds or nickel-cobalt-manganese composite compounds. Here, compounds containing at least nickel are collectively referred to as "nickel compounds."

[0018] In black mass, the nickel content may be, for example, 3% to 30% by mass, the cobalt content may be, for example, 3% to 30% by mass, and the manganese content may be, for example, 0% to 30% by mass. The content of each metal element in black mass is not limited to the above, and depending on the recovered used battery, the nickel content may be 30% to 90% by mass.

[0019] Oxides containing primary metals (i.e., nickel, cobalt, and manganese) are in high demand as raw materials for positive electrode active materials in non-aqueous electrolyte secondary batteries. Non-aqueous electrolyte secondary batteries include lithium-ion batteries, lithium metal batteries, and all-solid-state batteries. Such oxides are usually manufactured using nickel sulfate as the main raw material. However, the process of producing nickel sulfate from raw material metal oxides such as black mass, which contain many impurities, consumes a large amount of energy, so process simplification is desired.

[0020] This disclosure relates to a process for obtaining a nickel compound with increased purity of the primary metal, which is the active ingredient, from a raw material metal oxide containing impurities. This disclosure can be described as a method for producing a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery.

[0021] <Leaching Process> The manufacturing method (M) comprises a step of mixing a raw material metal oxide with an acidic aqueous solution to obtain a first solution containing ions of a primary and secondary metal by acid leaching. For example, by mixing the raw material metal oxide with an acidic aqueous solution, the primary and secondary metals contained in the raw material metal oxide dissolve as ions into the acidic aqueous solution.

[0022] The concentration of the acidic aqueous solution is not particularly limited, but may be, for example, 0.1 mol / L to 5 mol / L, or 1 mol / L to 5 mol / L. In addition to sulfuric acid, nitric acid, hydrochloric acid, organic acids, etc., can be used as the acid. The temperature of the acidic aqueous solution is not particularly limited, but may be, for example, 60°C to 90°C, preferably 65°C to 80°C, and more preferably 70°C to 80°C. That is, a mixture containing the raw material metal oxide and the acidic aqueous solution may be heated to acid-leach the ions of the first and second metals.

[0023] The pH of the first solution containing various metal ions obtained by acid leaching is, for example, pH 4.0 or lower, and preferably may be controlled to pH 3.0 or lower or 2.0 or lower. The total ion concentration of the first and second metals in the first solution may be controlled to, for example, 0.1 mol / L to 3 mol / L, or to 1 mol / L to 3 mol / L.

[0024] In the leaching process, a reducing agent may be mixed with the raw material metal oxide together with an acidic aqueous solution to acid-leach the ions of the first metal and the second metal. By using the reducing agent in combination with the acid, the trivalent first metal is reduced to divalent, and the dissolution rate of the ions of the first metal is improved. For example, by adding an appropriate amount of a reducing agent to a mixture of the raw material metal oxide and an aqueous sulfuric acid solution, the trivalent nickel is reduced to divalent, and the dissolution rate of nickel ions is improved. The trivalent nickel is reduced to divalent nickel by the following reaction. Other metals generally react in a similar manner.

[0025] Ni ２ O ３ + NaHSO ３ + 2H ２ O → 2Ni ２＋ + SO ４ ２－ + Na ＋ + 5H ＋

[0026] As the reducing agent, a reducing agent exhibiting weak acidity is preferable. For example, NaHSO ３ , ascorbic acid, citric acid, oxalic acid, hydrogen peroxide, etc. can be used. Among them, hydrogen peroxide is composed of hydrogen and oxygen and has little influence on the reaction system, so it is preferable to use hydrogen peroxide. The amount of hydrogen peroxide used per 100 parts by mass of the raw material metal oxide may be, for example, 1.5 mol to 5 mol, may be 3 mol to 5 mol, or may be 4 mol to 5 mol. Setting the amount of hydrogen peroxide used within the above range is preferable in terms of increasing the leaching rate.

[0027] <First production step> Next, a first production step is performed in which the first solution is neutralized with a first alkali to produce a solid content containing the second metal and a second solution containing at least the ions of the first metal. In the first production step, a solid content containing at least one selected from the group consisting of calcium, iron, silicon, zinc, copper, aluminum, and lithium among the second metals is produced. Most of the ions of the second metal precipitate at a pH of 7.0 or less (for example, pH = 5.0 to 7.0). For example, the following reaction proceeds.

[0028] H ２ SO4 + CaCO ３ → CaSO４ +H ２ O + CO ２ FeSO4 + 2H ２ O → Fe(OH)2 + H ２ SO4 Fe(OH)2 + O2 → +Fe ２ O3 + H ２ O

[0029] For the first alkali for neutralization, for example, metal hydroxides and carbonates such as sodium hydroxide, lime, calcium carbonate, calcium oxide, calcium hydroxide, sodium carbonate, etc. can be used. An aqueous solution in which the first alkali is dissolved in water may also be used. The concentration of the first alkali aqueous solution may be, for example, 1 mol / L to 10 mol / L.

[0030] The neutralization may be carried out in two steps. In the first neutralization, when the pH is controlled to 4.5 to 5.5, Cu, Al, Fe, etc. precipitate. After the precipitate is separated into solid and liquid by filtration, the second neutralization is carried out. In the second neutralization, when the pH is controlled to 6 to 7, Cu, Fe, Al, Zn, etc. precipitate. Also, by bubbling oxygen into the first solution, divalent metal ions may be oxidized to trivalent and precipitated. For example, by bubbling oxygen, Fe ２＋ ions can be precipitated as Fe ２ O ３ and precipitated.

[0031] <First solid-liquid separation step> At any time, a step of separating the second solution and the solid content into solid and liquid is carried out. When the neutralization is carried out in two steps, the step of separating the solid and liquid may be carried out multiple times. The solid-liquid separation can be carried out by methods such as a vacuum dehydrator, a centrifugal concentrator dehydrator, a multi-disc dehydrator, a filter press, a belt press, a screw press, a rotary drum screen, a belt screen, a vibrating screen, a multi-plate wave filter, suction filtration, etc. In the second solution, ions of the first metal are dissolved, and ions of some second metals such as magnesium may also be included. The concentration of the ions of the first metal in the second solution is, for example, 0.5 mol / L to 2.5 mol / L. Here, it is preferable to generate a second solution with a pH of 5.0 to 7.0.

[0032] <Second Production Step> Next, the separated second solution is mixed with a second alkali containing at least a metal hydroxide and ammonia to produce a nickel compound containing at least nickel as the first metal, and a third solution (residual solution).

[0033] The second solution contains at least nickel and may contain at least one selected from the group consisting of cobalt, manganese, and magnesium. By adding a second alkali to the second solution and controlling the pH to 10-12, the first metals, nickel, cobalt, and manganese, form precipitates. This allows for the production of a nickel compound containing at least nickel, for example, with a sufficiently reduced impurity content. Furthermore, when the first metals include nickel, cobalt, and manganese, a nickel-cobalt-manganese composite compound can be obtained. Such compounds can be suitably used as raw materials for positive electrode active materials in lithium-ion secondary batteries, lithium metal secondary batteries, and the like.

[0034] For the second alkali, for example, metal hydroxides such as sodium hydroxide and potassium hydroxide, and ammonia can be used. An aqueous solution obtained by dissolving the second alkali in water may also be used. The overall concentration of the aqueous solution of the second alkali is, for example, 0.5 N (normal) to 10 N, but may also be 0.5 N to 2 N or 0.5 N to 1.5 N. The concentration of the aqueous solution of the metal hydroxide may also be 0.5 N (normal) to 10 N, but may also be 0.5 N to 2 N or 0.5 N to 1.5 N.

[0035] When the pH is controlled to 10 or higher, lithium ions remain in the solution. Magnesium coprecipitates with the primary metal, but the amount of Mg is trace (e.g., less than 0.3% by mass).

[0036] Here, it is important to mix ammonia into the second solution as part of the second alkali. In the presence of both ammonia and other alkalis, the rate of nickel compound precipitate formation is slow, and the precipitate particle size grows large. The particle size can be controlled by appropriately adjusting the amount of ammonia used.

[0037] Ammonia may be added by bubbling it into the second solution, or an aqueous ammonia solution may be used. The concentration of the aqueous ammonia solution is, for example, 0.01 N to 2 N, and may also be 0.5 N to 1.5 N.

[0038] In one preferred mixing method, the second solution and the metal hydroxide aqueous solution are added simultaneously to an ammonia aqueous solution and mixed. Alternatively, the metal hydroxide aqueous solution is added to a mixture obtained by mixing the ammonia aqueous solution and the second solution. When mixed in this manner, the reaction between the first metal ion and the second alkali does not proceed excessively quickly, making it easier to increase the particle size of the nickel compound.

[0039] <Second Solid-Liquid Separation Process> Next, a solid-liquid separation process is carried out to separate the third solution from the solid components. Solid-liquid separation can be performed using methods such as a vacuum dehydrator, centrifugal concentrate dehydrator, multi-disc dehydrator, filter press, belt press, screw press, rotary drum screen, belt screen, vibrating screen, multi-plate wave filter, and suction filtration.

[0040] The median diameter at 50% of the cumulative volume in the volume-based particle size distribution of the nickel compound (hereinafter referred to as "D50") is preferably greater than 0.5 μm. In this case, solid-liquid separation can be performed quickly and efficiently, and the productivity of the nickel compound is dramatically improved. The D50 of the nickel compound may be controlled to be between 1 μm and 30 μm, between 2 μm and 15 μm, or between 4 μm and 10 μm.

[0041] If ammonia is not used in the second production step, the D50 of the nickel compound will become very small, requiring a long time for solid-liquid separation.

[0042] <Nickel Compounds> Nickel compounds separated by solid-liquid separation contain hydroxides and, typically, sulfates. That is, nickel compounds are obtained as a mixture of hydroxide sulfate, hydroxide, and sulfate. The sulfate content in nickel compounds is, for example, 20 mol% or less.

[0043] At least a portion of the nickel compound obtained through the above process is of formula (1): (Ni ａ Co ｂ Mn ｃ ) (OH) ｘ (SO ４ ) ｙ It can be expressed as follows. In this case, the following conditions may be satisfied: a≧0.1, b≧0.01, c≧0, a+b+c=1, 1.5≦x+2y≦2.5, y≦0.2. In equation (1), the following conditions may be satisfied: a≧0.5 and c≧0.1. In addition, nickel compounds may contain magnesium or zinc, which are secondary metals, as impurities in amounts of about 0.1 to 1 atomic percent.

[0044] <Crystallization Process> A nickel compound, or a mixture of hydroxide sulfate, hydroxide, and sulfate may be further dissolved in an aqueous sulfuric acid solution for component adjustment and pH adjustment. From the resulting aqueous nickel sulfate solution, nickel hydroxide containing at least nickel as the primary metal may be crystallized. For example, by dissolving alkali in the aqueous nickel sulfate solution, a high-purity nickel hydroxide can be obtained. Through crystallization, the value of y in formula (1), which shows the composition of the nickel compound, can be reduced to, for example, y ≤ 0.05. The obtained hydroxide can be suitably used as a raw material for positive electrode active materials in lithium-ion secondary batteries, lithium metal secondary batteries, etc.

[0045] (Note) The following technologies are disclosed in accordance with the above description. (Technology 1) A method for producing a nickel compound, comprising: a step of preparing a raw material metal oxide comprising a first metal comprising at least nickel and a second metal comprising at least one selected from the group consisting of magnesium, calcium, iron, silicon, zinc, copper, aluminum, and lithium; a step of mixing the raw material metal oxide with an aqueous acid solution to obtain a first solution containing ions of the first and second metals by acid leaching; a first production step of neutralizing the first solution with a first alkali to produce a solid component containing the second metal and a second solution containing at least ions of the first metal; a step of solid-liquid separation of the second solution and the solid component; a second production step of mixing the second solution with a second alkali containing at least a metal hydroxide and ammonia to produce a nickel compound comprising at least nickel as the first metal and a third solution; and a step of solid-liquid separation of the nickel compound and the third solution. (Technical 2) A method for producing a nickel compound according to Technical 1, wherein the first metal further comprises at least one selected from the group consisting of cobalt and manganese. (Technical 3) A method for producing a nickel compound according to Technical 1 or 2, wherein the nickel compound comprises a hydroxide sulfate, a hydroxide, and a sulfate, and the content of the sulfate is 20 mol% or less. (Technical 4) A nickel compound comprising the formula: (Ni ａ Co ｂ Mn ｃ ) (OH) ｘ (SO ４ ) ｙA method for producing a nickel compound according to any one of the technologies 1 to 3, wherein when expressed as, a≧0.1, b≧0.01, c≧0, a+b+c=1, 1.5≦x+2y≦2.5, and y≦0.2 are satisfied. (Technology 5) A method for producing a nickel compound according to any one of the technologies 1 to 4, wherein the pH of the second solution is in the range of 5.0 to 7.0. (Technology 6) A method for producing a nickel compound according to any one of the technologies 1 to 5, wherein the pH of the third solution is in the range of 10 to 12. (Technology 7) A method for producing a nickel compound according to any one of the technologies 1 to 6, wherein in the second production step, the nickel compound is produced in which the median diameter of 50% of the cumulative volume in the volume-based particle size distribution exceeds 0.5 μm. (Technical 8) A method for producing a nickel compound according to any one of Technical 1 to 7, wherein the concentration of the first metal ions in the second solution is 0.5 mol / L to 2.5 mol / L, the metal hydroxide is mixed with the second solution as an alkaline aqueous solution of 0.5 N to 2 N, and the ammonia is mixed with the second solution as an aqueous ammonia aqueous solution of 0.01 N to 2 N. (Technical 9) A method for producing a nickel compound according to any one of Technical 1 to 8, wherein in the step of obtaining the first solution, a reducing agent is mixed with the raw material metal oxide together with the acid aqueous solution to acid-leach the ions of the first metal and the second metal. (Technical 10) A method for producing a nickel compound according to any one of Technical 1 to 9, wherein in the first step, a mixture containing the raw material metal oxide and the acid aqueous solution is heated to acid-leach the ions of the first metal and the second metal. (Technical 11) A method for producing nickel hydroxide, further comprising the steps of: dissolving a nickel compound obtained by the method described in any one of Technical 1 to 10 in an aqueous sulfuric acid solution to obtain an aqueous nickel sulfate solution; and crystallizing a nickel hydroxide containing at least nickel as the first metal from the aqueous nickel sulfate solution.

[0046] [Examples] The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0047] <Example 1> <Preparation Step> Black mass (a metal oxide containing nickel, cobalt, and manganese, and containing a secondary metal as an impurity) was prepared as the raw material metal compound.

[0048] <Leaching Process> 20 g of black trout was dispersed in 500 ml of water and mixed with 125 ml of sulfuric acid solution (6.5 mol / L (13 N)) and 80 ml of hydrogen peroxide solution (33 mol / L) to make the overall sulfuric acid concentration 0.8 mol / L (1.6 N). The mixture was heated to 70°C and acid leached to obtain the first solution (pH = 1.9). The amount of hydrogen peroxide solution used per 100 g of black trout was 3.2 mol.

[0049] <First Production Process and First Solid-Liquid Separation Process> Calcium carbonate was added to the first solution as the first alkali, and the pH was controlled to 4.5-5.5 to perform the first neutralization, causing the solid containing the second metal to precipitate. The solid containing the second metal was separated from the solution by suction filtration. The solid contains calcium sulfate, but the separation of calcium sulfate does not take time.

[0050] Next, sodium hydroxide was added to the solution to control the pH to 6, and a second neutralization was performed, causing solid components containing Cu, Fe, Al, Si, etc. to precipitate. The solid components containing the second metal were separated from the second solution by suction filtration.

[0051] <Second Production Step> In the second solution (the ion concentration of the first metal is 1.0 mol / L), a 1.0 mol / L NaOH aqueous solution and a 0.2 mol / L ammonia aqueous solution were mixed as the second alkali aqueous solution. Specifically, 500 mL of the second solution and 1000 mL of the NaOH aqueous solution were added to 125 mL of the ammonia aqueous solution in a beaker using a double-jet method, and the three were mixed simultaneously. This produced nickel compound A1 containing nickel, cobalt, and manganese, and the third solution. The pH of the third solution was controlled to 10.5.

[0052] <Second Solid-Liquid Separation Step> The nickel compound was separated from the third solution by suction filtration. When the nickel compound obtained after drying was observed with an electron microscope, the particle size was in the range of 6 μm to 30 μm, and the filtration time was approximately 15 minutes.

[0053] Example 2: The amount of hydrogen peroxide solution used in the leaching step was changed to 40 ml, and the heating temperature of the mixture was changed to 60°C. The amount of hydrogen peroxide solution used per 100 g of black mass was 1.6 mol. In addition, in the second production step, the volume of the ammonia aqueous solution in the beaker was changed to 250 mL. Except as above, the same procedure as in Example 1 was performed to obtain nickel compound A2. When the nickel compound obtained after drying was observed with an electron microscope, the particle size was in the range of 1 μm to 11 μm, and the time required for filtration was approximately 15 minutes.

[0054] <Comparative Example 1> The amount of hydrogen peroxide solution used in the leaching process was changed to 14.4 ml, and the mixture was acid-leached at 30°C without heating. Also, aqueous ammonia solution was not used in the second production process. Except as above, the same procedure as in Example 1 was performed to obtain nickel compound B1. When the nickel compound obtained after drying was observed with an electron microscope, the particle size was less than 0.5 μm, and the time required for filtration was 90 minutes.

[0055] Table 1 shows the main manufacturing conditions and results for each example.

[0056]

[0057] As shown in Table 1, in Examples 1 and 2, the use of ammonia in the second production step resulted in larger nickel compound particle sizes, allowing for efficient filtration. On the other hand, in Comparative Example 1, the nickel compound particle size was very small, requiring a long time for filtration. Furthermore, it can be seen that the leaching rate of metal ions is significantly improved by raising the temperature of the mixture in the leaching step to 60°C or higher (and even 70°C or higher) and using a sufficient amount of reducing agent. The NiCoMn leaching rate was calculated using the following formula.

[0058] NiCoMn leaching rate (%) = (Mass of black mass used to obtain the first solution - Mass of undissolved residue) / Mass of black mass used to obtain the first solution

[0059] The method for producing nickel compounds described herein is low-cost, has a low environmental impact, and is highly economically rational.

[0060] Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

Claims

1. A method for producing a nickel compound, comprising: a step of preparing a raw material metal oxide comprising a first metal comprising at least nickel and a second metal comprising at least one selected from the group consisting of magnesium, calcium, iron, silicon, zinc, copper, aluminum, and lithium; a step of mixing the raw material metal oxide with an acidic aqueous solution to obtain a first solution containing ions of the first and second metals by acid leaching; a first production step of neutralizing the first solution with a first alkali to produce a solid component containing the second metal and a second solution containing at least ions of the first metal; a step of solid-liquid separation of the second solution and the solid component; a second production step of mixing the second solution with a second alkali containing at least a metal hydroxide and ammonia to produce a nickel compound comprising at least nickel as the first metal and a third solution; and a step of solid-liquid separation of the nickel compound and the third solution.

2. The method for producing a nickel compound according to claim 1, wherein the first metal further comprises at least one selected from the group consisting of cobalt and manganese.

3. The method for producing the nickel compound according to claim 1, wherein the nickel compound comprises a hydroxide sulfate, a hydroxide, and a sulfate, and the content of the sulfate is 20 mol% or less.

4. The nickel compound is given by formula: (Ni ａ Co ｂ Mn ｃ ) (OH) ｘ (SO ４ ) ｙ A method for producing a nickel compound according to claim 1, wherein when expressed as, a≧0.1, b≧0.01, c≧0, a+b+c=1, 1.5≦x+2y≦2.5, and y≦0.2 are satisfied.

5. The method for producing a nickel compound according to claim 1, wherein the pH of the second solution is in the range of 5.0 to 7.

0.

6. The method for producing a nickel compound according to claim 1, wherein the pH of the third solution is in the range of 10 to 12.

7. The method for producing a nickel compound according to claim 1, wherein in the second production step, the nickel compound is produced in which the median diameter of 50% of the cumulative volume in the volume-based particle size distribution exceeds 0.5 μm.

8. The method for producing a nickel compound according to claim 1, wherein the concentration of ions of the first metal in the second solution is 0.5 mol / L to 2.5 mol / L, the metal hydroxide is mixed with the second solution as an alkaline aqueous solution of 0.5 N to 2 N, and the ammonia is mixed with the second solution as an aqueous ammonia aqueous solution of 0.01 N to 2 N.

9. The method for producing a nickel compound according to claim 1, wherein in the step of obtaining the first solution, a reducing agent is mixed with the raw material metal oxide together with the acid aqueous solution to acid-leach ions of the first metal and the second metal.

10. The method for producing a nickel compound according to claim 1, wherein in the first step, a mixture containing the raw material metal oxide and the acid aqueous solution is heated to acid-leach ions of the first metal and the second metal.

11. A method for producing nickel hydroxide, further comprising the steps of: dissolving a nickel compound obtained by the method of claim 1 in an aqueous sulfuric acid solution to obtain an aqueous nickel sulfate solution; and crystallizing a nickel hydroxide containing at least nickel as the first metal from the aqueous nickel sulfate solution.

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