Alkali metal compounds and alkaline earth metal compounds, and methods for producing them.

Abstract

To provide a simple method for producing alkali metal compounds and / or alkaline earth metal compounds with reduced nickel concentration. [Solution] A method for producing an alkali metal compound and / or an alkaline earth metal compound, comprising a purification step of filtering a first aqueous solution containing the alkali metal compound and / or the alkaline earth metal compound and nickel through a filter to obtain a second aqueous solution in which the concentration of nickel has decreased, wherein the pore size of the filter is 0.5 μm or less.

Description

Technical Field

[0001] The present invention relates to alkali metal compounds, alkaline earth metal compounds, and methods for producing them.

Background Art

[0002] Alkali metal compounds or alkaline earth metal compounds are used in the manufacture of precision instruments and the like, and their high purity is required.

[0003] Nickel members may be used in the production apparatus of alkali metal compounds or alkaline earth metal compounds. When an aqueous solution containing these compounds comes into contact with the nickel member, nickel may be mixed into the aqueous solution as an impurity.

[0004] Patent Document 1 discloses a method for purifying an alkali hydroxide. In an aqueous solution of an alkali hydroxide containing alkaline earth metal and iron as impurities, an aqueous solution of hydrogen peroxide and an inorganic acid salt of a rare earth element are added and stirred, and a coprecipitate is formed under cooling, and this coprecipitate is removed by filtration. It has been reported that by this method, heavy metals such as nickel are adsorbed and precipitated on the surface of the amorphous hydroxide of the rare earth element, and a high-purity alkali hydroxide solution can be obtained by filtering this with a filter.

[0005] Patent Document 2 discloses a method for purifying an alkaline aqueous solution, characterized in that an alkaline aqueous solution containing metal impurities is brought into contact with at least one of a fibrous weakly basic anion exchanger and a chelating material to remove the metal impurities from the alkaline aqueous solution. It has been reported that by this method, metal impurities contained in an alkaline aqueous solution can be removed simply and at a high rate, and the residual metal impurities can be sufficiently reduced.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Publication No. 3-75216 [Patent Document 2] Japanese Patent Publication No. 2011-051833 [Overview of the project] [Problems that the invention aims to solve]

[0007] The method described in Patent Document 1 requires cooling and standing after adding hydrogen peroxide solution and an inorganic salt of a rare earth element. Therefore, the production of high-purity alkali hydroxide is time-consuming and requires cooling equipment and storage tanks.

[0008] In the method described in Patent Document 2, the flow rate SV of the alkaline aqueous solution is slow, at a maximum of 50 (1 / h). Furthermore, the use of a chelating agent is costly, and there is a risk of the chelating agent itself contaminating the alkaline aqueous solution. Additionally, continuous filtration may result in the nickel not being captured and being released into the solution.

[0009] The present invention aims to provide a simple method for producing alkali metal compounds and / or alkaline earth metal compounds with reduced nickel concentration. [Means for solving the problem]

[0010] The inventors have discovered that alkali metal compounds and / or alkaline earth metal compounds with reduced nickel concentration can be produced by filtering an aqueous solution containing an alkali metal compound and / or alkaline earth metal compound through a filter having a predetermined pore size.

[0011] The present invention includes the following embodiments. [1] A method for producing alkali metal compounds and / or alkaline earth metal compounds that exhibit alkalinity, The process includes a purification step of filtering a first aqueous solution containing the alkali metal compound and / or the alkaline earth metal compound and nickel through a filter to obtain a second aqueous solution in which the concentration of nickel is reduced. The pore size of the aforementioned filter is 0.5 μm or less. Manufacturing method. [2] The manufacturing method according to [1], wherein the concentration of nickel contained in the first aqueous solution is 0.01 to 10,000 μg / kg, based on an aqueous solution in which the concentration of the alkali metal or alkaline earth metal is 12.8 mol / L. [3] The manufacturing method according to [1] or [2], wherein the concentration of nickel contained in the first aqueous solution is 1 to 50 μg / kg, based on an aqueous solution in which the concentration of the alkali metal or alkaline earth metal is 12.8 mol / L. [4] The manufacturing method according to any one of [1] to [3], wherein the nickel removal rate in the refining step is 60% or more. [5] The manufacturing method according to any one of [1] to [4], wherein the nickel removal rate in the refining step is 80% or more. [6] The manufacturing method according to any one of [1] to [5], wherein the concentration of nickel contained in the second aqueous solution is 25 μg / kg or less, based on an aqueous solution in which the concentration of the alkali metal or alkaline earth metal is 12.8 mol / L. [7] The first aqueous solution contains the alkali metal compound, The method for producing an alkali metal compound according to any one of [1] to [6], wherein the alkali metal compound comprises at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, and potassium carbonate. [8] The manufacturing method according to any one of [1] to [7], wherein the concentration of the alkali metal compound and / or the alkaline earth metal compound contained in the first aqueous solution is 25 to 52% by mass. [9] The production method according to any one of [1] to [8], wherein the first aqueous solution or its precursor solution contacts the inner surface of the production apparatus of the alkali metal compound and / or the alkaline earth metal compound before the purification step.

[10] The production method according to [9], wherein the inner surface of the production apparatus contains nickel.

[11] The production method according to any one of [1] to

[10] , wherein at least one pretreatment selected from the group consisting of aggregation, precipitation, and deposition is not performed on the nickel contained in the first aqueous solution.

[12] The production method according to any one of [1] to

[11] , wherein the first aqueous solution substantially does not contain a chemical for aggregating, precipitating, or depositing the nickel.

[13] The production method according to

[12] , wherein the chemical is at least one selected from the group consisting of a combination of hydrogen peroxide solution and an inorganic acid salt of a rare earth element, hypochlorous acid or its salt, a sulfur compound, a chelating agent, polyaluminum chloride, and ammonium sulfate.

[14] An alkali metal compound or an alkaline earth metal compound showing alkalinity, the number of particles having a particle size of 0.5 μm or more contained in the alkali metal compound or the alkaline earth metal compound is 100 particles / mL or less based on an aqueous solution having a concentration of the alkali metal or the alkaline earth metal of 1 mol / L, the concentration of nickel contained in the alkali metal compound or the alkaline earth metal compound is 10,000 μg / kg or less based on an aqueous solution having a concentration of the alkali metal or the alkaline earth metal of 12.8 mol / L, An alkali metal compound or an alkaline earth metal compound.

[15] The alkali metal compound or the alkaline earth metal compound according to

[14] , wherein the alkali metal compound or the alkaline earth metal compound is selected from the group consisting of potassium hydroxide, sodium hydroxide, and potassium carbonate. [Effects of the Invention]

[0012] The present invention can provide a simple method for producing an alkali metal compound and / or an alkaline earth metal compound with a reduced nickel concentration.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof.

[0014] <Manufacturing Method> One embodiment of the present invention is A method for producing an alkali metal compound showing alkalinity and / or an alkaline earth metal compound showing alkalinity, including a purification step of filtering a first aqueous solution containing the alkali metal compound and / or the alkaline earth metal compound and nickel with a filter to obtain a second aqueous solution with a reduced nickel concentration. The manufacturing method relates to a manufacturing method in which the pore diameter of the filter is 0.5 μm or less.

[0015] The manufacturing method according to this embodiment can also be expressed as a purification method for an alkali metal compound showing alkalinity and / or an alkaline earth metal compound showing alkalinity.

[0016] The manufacturing method according to this embodiment can also be expressed as a method for removing nickel contained in an alkali metal compound showing alkalinity and / or an alkaline earth metal compound showing alkalinity.

[0017] In the manufacturing method according to this embodiment, nickel can be removed simply by filtering an aqueous solution with a filter having a predetermined pore diameter, so the operation is simple.

[0018] [First Aqueous Solution] The first aqueous solution is an aqueous solution filtered with a filter having a pore diameter of 0.5 μm or less in the purification step.

[0019] The first aqueous solution or its precursor solution is, for example, one that has been in contact with the inner surface (specifically, an inner surface containing nickel) of the manufacturing apparatus for alkali metal compounds and / or alkaline earth metal compounds before the purification process. Since nickel is easily introduced as an impurity into the first aqueous solution or its precursor solution that has been in contact with an inner surface containing nickel, the removal of nickel is particularly necessary.

[0020] In this specification, the term "precursor solution" of the first aqueous solution means the aqueous solution that has undergone any treatment prior to filtration in the purification process described above, if such treatment exists prior to that treatment. For example, if a prior purification treatment exists before the purification process described above, the aqueous solution that has undergone the prior purification treatment is the precursor solution and not the first aqueous solution.

[0021] The precursor solution may be, for example, an aqueous solution obtained by concentrating an aqueous solution of an alkaline alkali metal compound and / or an alkaline earth metal compound at a high temperature (e.g., 70°C to 150°C, 90°C to 120°C, or 95°C to 110°C) to precipitate crystals of the compound, and then isolating the crystals from the slurry containing the crystals (hereinafter also referred to as the crystallization step). If the alkaline alkali metal compound and / or alkaline earth metal compound is potassium hydroxide, the crystallization step can be carried out, for example, by referring to International Publication 2007 / 018203. One embodiment is a method for producing alkali metal compounds and / or alkaline earth metal compounds that exhibit alkalinity, The process includes a purification step of filtering a first aqueous solution containing the alkali metal compound and / or the alkaline earth metal compound and nickel through a filter to obtain a second aqueous solution in which the concentration of nickel is reduced. The pore size of the aforementioned filter is 0.5 μm or less. The first aqueous solution includes a step of preparing it by obtaining the crystallization step, This is the manufacturing method.

[0022] It is preferable that the first aqueous solution has not undergone any pretreatment for filtration. Examples of pretreatment for filtration include treatments that cause nickel contained in the first aqueous solution to agglomerate, precipitate, or precipitate (hereinafter referred to as "aggregation, etc."). Pretreatment is a treatment that is actively performed to cause nickel to agglomerate, etc. (for example, a treatment that involves adding a chemical agent to cause nickel to agglomerate, etc.). Therefore, spontaneous agglomeration, etc. of nickel is not included in the pretreatment.

[0023] Preferably, the first aqueous solution contains substantially no agents for agglomerating nickel. "Substantially no agents" means that it does not contain a sufficient amount of agents to agglomerate nickel contained in the first aqueous solution (in other words, no agents have been added for the purpose of agglomerating nickel). Therefore, for example, even if an agent for agglomerating nickel is added to a precursor solution of the first aqueous solution, and after the nickel and agent are removed, a small amount of residue of that agent is still present in the first aqueous solution, the first aqueous solution will still be considered substantially free of agents.

[0024] Examples of agents used to coagulate nickel include a combination of hydrogen peroxide and an inorganic salt of a rare earth element, hypochlorous acid or its salt, sulfur compounds, chelating agents, polyaluminum chloride, and ammonium sulfate.

[0025] (Alkali metal compounds and alkaline earth metal compounds) The first aqueous solution contains an alkali metal compound and / or an alkaline earth metal compound that exhibits alkalinity.

[0026] The alkali metal compound may be a single type or a combination of multiple types. The alkaline earth metal compound may be a single type or a combination of multiple types.

[0027] Examples of alkali metal compounds include sodium compounds, which exhibit alkaline properties. Examples of sodium compounds include sodium hydroxide, sodium carbonate, and sodium bicarbonate.

[0028] Examples of alkali metal compounds include potassium compounds, which exhibit alkaline properties. Examples of potassium compounds that exhibit alkalinity include potassium hydroxide, potassium carbonate, and potassium bicarbonate.

[0029] Examples of alkaline earth metal compounds include calcium compounds that exhibit alkalinity. Examples of calcium compounds include calcium hydroxide, calcium carbonate, calcium oxide, and calcium bicarbonate.

[0030] The concentration of alkali metal compounds and / or alkaline earth metal compounds in the first aqueous solution is preferably 5 to 52% by mass, and more preferably 25 to 52% by mass. When the alkali metal compound and / or alkaline earth metal compound is sodium hydroxide, its concentration is preferably 5 to 49% by mass, and more preferably 25 to 49% by mass. When the alkali metal compound and / or alkaline earth metal compound is potassium hydroxide, its concentration is preferably 5 to 49% by mass, and more preferably 32 to 49% by mass. When the alkali metal compound and / or alkaline earth metal compound is potassium carbonate, its concentration is preferably 5 to 51% by mass, and more preferably 49 to 51% by mass. If the first aqueous solution contains alkali metal compounds and alkaline earth metal compounds, the concentration refers to the total concentration of the alkali metal compounds and alkaline earth metal compounds.

[0031] In this specification, the concentrations of alkali metal compounds and alkaline earth metal compounds are measured by titration. For example, the concentration of sodium hydroxide is measured by a neutralization titration method using hydrochloric acid (indicator: phenolphthalein solution). For example, the concentration of potassium hydroxide is measured by a neutralization titration method using hydrochloric acid (indicator: phenolphthalein solution). For example, the concentration of potassium carbonate is measured by potentiometric titration using hydrochloric acid. The specific measurement method is as described in the examples below.

[0032] (impurities) The first aqueous solution contains nickel as an impurity.

[0033] The nickel concentration in the first aqueous solution is preferably 0.01 to 10,000 μg / kg, more preferably 0.1 to 1,000 μg / kg, even more preferably 1 to 100 μg / kg, and particularly preferably 1 to 50 μg / kg, based on an aqueous solution in which the alkali metal or alkaline earth metal concentration is 12.8 mol / L.

[0034] The actual concentration of nickel in the first aqueous solution is preferably 0.01 to 1,000 μg / kg, more preferably 0.1 to 100 μg / kg, even more preferably 1 to 50 μg / kg, and particularly preferably 1 to 10 μg / kg.

[0035] According to the manufacturing method of this embodiment, nickel can be removed even when the concentration of nickel in the first aqueous solution is low.

[0036] In this specification, the nickel concentration is measured by inductively coupled plasma mass spectrometry (ICP-MS). The specific measurement method is as described in the examples below.

[0037] The first aqueous solution may contain impurities other than nickel. Examples of impurities other than nickel include iron and copper.

[0038] [filtration] The first aqueous solution is filtered using a filter with a pore size of 0.5 μm or less. By filtering the first aqueous solution with a filter with a pore size of 0.5 μm or less, nickel contained in the first aqueous solution can be removed.

[0039] (filter) The pore size of the filter is 0.5 μm or less, preferably 0.1 to 0.5 μm, and more preferably 0.2 to 0.5 μm.

[0040] The pore size of the filter is measured using the bubble point test method. If the filter is a commercially available product, refer to the pore size specified in the product's instruction manual.

[0041] The material of the filter is not particularly limited. Examples of filter materials include resins such as polytetrafluoroethylene (PTFE), polypropylene, and polyethersulfone. Preferably, the filter does not contain, for example, ion exchangers, chelating agents, and activated carbon.

[0042] (Filtration conditions) The filtration conditions are not particularly limited. The temperature of the first aqueous solution during filtration may be, for example, 5 to 50°C. The filtration pressure may be, for example, 0.01 to 0.4 MPa.

[0043] (Nickel removal rate) The percentage of nickel removed from the first aqueous solution by filtration ("nickel removal rate") is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, particularly preferably 90% or more, and most preferably 95% or more.

[0044] Since a higher nickel removal rate is preferable, there is no particular upper limit, but it may be, for example, 100%, 99%, 98%, or 97%.

[0045] The nickel removal rate can be calculated using the following formula. Note that the "nickel concentration of the first aqueous solution" and the "nickel concentration of the second aqueous solution" in the following formula are based on an aqueous solution with an alkali metal or alkaline earth metal concentration of 12.8 mol / L. Nickel removal rate (%) = {[(Nickel concentration in the first aqueous solution) - (Nickel concentration in the second aqueous solution)] / (Nickel concentration in the first aqueous solution)} × 100

[0046] [Second aqueous solution] The second aqueous solution is an aqueous solution in which the nickel concentration has been reduced, obtained by filtering the first aqueous solution through a filter with a pore size of 0.5 μm or less.

[0047] The nickel concentration in the second aqueous solution is preferably 10,000 μg / kg or less, more preferably 1,000 μg / kg or less, even more preferably 50 μg / kg or less, particularly preferably 25 μg / kg or less, and most preferably 10 μg / kg or less, based on an aqueous solution in which the alkali metal or alkaline earth metal concentration is 12.8 mol / L.

[0048] Since a lower nickel concentration in the second aqueous solution (based on an aqueous solution with an alkali metal or alkaline earth metal concentration of 12.8 mol / L) is preferable, there is no particular lower limit, but for example, it may be 1 μg / kg, 0.5 μg / kg, or 0.2 μg / kg.

[0049] The actual concentration of nickel in the second aqueous solution is preferably 1,000 μg / kg or less, more preferably 100 μg / kg or less, even more preferably 25 μg / kg or less, particularly preferably 10 μg / kg or less, and most preferably 5 μg / kg or less.

[0050] Since a lower actual concentration of nickel in the second aqueous solution is preferable, there is no particular lower limit, but for example, it may be 0.5 μg / kg, 0.1 μg / kg, or 0.01 μg / kg.

[0051] <Alkali metal compounds / Alkaline earth metal compounds> One embodiment of the present invention is Alkali metal compounds exhibiting alkalinity or alkaline earth metal compounds exhibiting alkalinity, The number of particles with a particle size of 0.5 μm or larger contained in the alkali metal compound or the alkaline earth metal compound is 100 particles / mL or less, based on an aqueous solution in which the alkali metal or alkaline earth metal has a concentration of 1 mol / L. The concentration of nickel contained in the alkali metal compound or the alkaline earth metal compound is 10,000 μg / kg or less, based on an aqueous solution in which the alkali metal or alkaline earth metal concentration is 12.8 mol / L. This relates to alkali metal compounds or alkaline earth metal compounds.

[0052] Specific examples of alkali metal compounds and alkaline earth metal compounds include those listed in the (Alkali Metal Compounds and Alkaline Earth Metal Compounds) section above.

[0053] [Particles] The number of particles contained in the alkali metal compound or alkaline earth metal compound is preferably 10 particles / mL or less, more preferably 1 particle / mL or less, and even more preferably 0.1 particles / mL or less.

[0054] Since a lower number of particles is preferable, there is no particular lower limit, but for example, it may be 0.8 particles / mL, 0.5 particles / mL, or 0.2 particles / mL.

[0055] The number of particles is based on an aqueous solution with an alkali metal or alkaline earth metal concentration of 1 mol / L. Furthermore, when determining the number of particles, it is not always necessary to prepare an aqueous solution with an alkali metal or alkaline earth metal concentration of 1 mol / L; the number of particles can be calculated by converting the concentration to 1 mol / L. For example, if the number of particles in an aqueous solution with an alkali metal or alkaline earth metal concentration of 0.5 mol / L is 1,000 particles / mL, the number of particles can be calculated as 2,000 particles / mL by converting the concentration to 1 mol / L (similarly, calculation by concentration conversion is possible when measuring the concentration of impurities).

[0056] The particles to be measured have a particle size of 0.5 μm or larger. There is no particular upper limit to the particle particle size, but for example, it may be 1 μm, 5 μm, or 10 μm.

[0057] The number of particles can be reduced by filtering an aqueous solution containing alkali metal compounds or alkaline earth metal compounds. For example, the number of particles can be adjusted by changing the pore size of the filter or the number of filtration cycles.

[0058] The number of particles can be measured using a commercially available particle counter. Specifically, it can be measured using a side scattering method with a semiconductor laser.

[0059] [impurities] (nickel) The concentration of nickel in the alkali metal compound or alkaline earth metal compound is preferably 10,000 μg / kg or less, more preferably 1,000 μg / kg or less, even more preferably 50 μg / kg or less, particularly preferably 25 μg / kg or less, and most preferably 10 μg / kg or less, based on an aqueous solution in which the alkali metal or alkaline earth metal concentration is 12.8 mol / L.

[0060] Since a lower concentration of nickel in the alkali metal compound or alkaline earth metal compound is preferable, there is no particular lower limit, but for example, it may be 1 μg / kg, 0.5 μg / kg, or 0.2 μg / kg.

[0061] The nickel concentration in alkali metal compounds or alkaline earth metal compounds is based on an aqueous solution with an alkali metal or alkaline earth metal concentration of 12.8 mol / L.

[0062] The concentration of nickel in alkali metal compounds or alkaline earth metal compounds can be reduced by filtering the aqueous solution containing the alkali metal compound or alkaline earth metal compound. For example, the nickel concentration can be adjusted by changing the pore size of the filter or the number of filtration cycles. [Examples]

[0063] The present invention will be described in more detail below using examples and comparative examples, but the technical scope of the present invention is not limited thereto.

[0064] The various values ​​in the examples may be preferred lower or upper limits in the embodiments of the present invention. Alternatively, two similar values ​​in the examples may be combined as appropriate to form a preferred numerical range.

[0065] Hereafter, "ppb" is synonymous with "μg / kg".

[0066] <Measurement method> [Measurement of nickel concentration in the first or second aqueous solution] Nickel extracted from a sample was measured using an inductively coupled plasma mass spectrometer (ICP-MS) (Agilent 7500cs, manufactured by Agilent Technologies, Inc.) in accordance with the method described in Japanese Patent Publication No. 2022-092416, and the nickel concentration was determined.

[0067] [Measurement of the concentration of alkali metal compounds or alkaline earth metal compounds in the first aqueous solution] The concentrations of sodium hydroxide and potassium hydroxide were measured by a neutralization titration method using hydrochloric acid (indicator: phenolphthalein solution).

[0068] [Measuring the number of particles] Using a particle counter (KS-42AF manufactured by Rion Co., Ltd.), the number of particles with a particle size of 0.5 μm or larger in the second aqueous solution was measured, using an aqueous solution with an alkali metal or alkaline earth metal concentration of 1 mol / L as a reference.

[0069] <Purification process> [Example 1] A first aqueous solution, in which the concentration of potassium hydroxide was 10% by mass and the concentration of nickel was 48 ppb (based on an aqueous solution with a potassium hydroxide concentration of 12.8 mol / L), was filtered through a hydrophilic PTFE filter with a pore size of 0.2 μm to obtain a second aqueous solution.

[0070] [Example 2] The same procedure as in Example 1 was followed, except that the pore size of the filter was changed to 0.5 μm.

[0071] [Example 3] A first aqueous solution, in which the potassium hydroxide concentration was 48% by mass and the nickel concentration was 31 ppb (based on an aqueous solution with a potassium hydroxide concentration of 12.8 mol / L), was filtered through a hydrophilic PTFE filter with a pore size of 0.2 μm to obtain a second aqueous solution.

[0072] [Example 4] The same procedure as in Example 3 was followed, except that the pore size of the filter was changed to 0.5 μm.

[0073] [Example 5] A first aqueous solution, in which the concentration of sodium hydroxide was 10% by mass and the concentration of nickel was 85 ppb (based on an aqueous solution with a sodium hydroxide concentration of 12.8 mol / L), was filtered through a hydrophilic PTFE filter with a pore size of 0.2 μm to obtain a second aqueous solution.

[0074] [Example 6] The same procedure as in Example 5 was followed, except that the pore size of the filter was changed to 0.5 μm.

[0075] [Comparative Example 1] A first aqueous solution, in which the potassium hydroxide concentration was 48% by mass and the nickel concentration was 4.8 ppb (based on an aqueous solution with a potassium hydroxide concentration of 12.8 mol / L), was filtered through a hydrophilic PTFE filter with a pore size of 1 μm to obtain a second aqueous solution.

[0076] [Comparative Example 2] A first aqueous solution, in which the potassium hydroxide concentration was 10% by mass and the nickel concentration was 4.8 ppb (based on an aqueous solution with a potassium hydroxide concentration of 12.8 mol / L), was filtered through a hydrophilic PTFE filter with a pore size of 1 μm to obtain a second aqueous solution.

[0077] The results of the examples and comparative examples are shown in Table 1. [Table 1]

Claims

1. A method for producing alkali metal compounds and / or alkaline earth metal compounds that exhibit alkalinity, The process includes a purification step of filtering a first aqueous solution containing the alkali metal compound and / or the alkaline earth metal compound and nickel through a filter to obtain a second aqueous solution in which the concentration of nickel is reduced. The pore size of the aforementioned filter is 0.5 μm or less. Manufacturing method.

2. The concentration of nickel contained in the first aqueous solution is 0.01 to 10,000 μg / kg, based on an aqueous solution in which the concentration of the alkali metal or alkaline earth metal is 12.8 mol / L. The manufacturing method according to claim 1.

3. The concentration of nickel contained in the first aqueous solution is 1 to 50 μg / kg, based on an aqueous solution in which the concentration of the alkali metal or alkaline earth metal is 12.8 mol / L. The manufacturing method according to claim 1.

4. The nickel removal rate in the aforementioned refining process is 60% or more. The manufacturing method according to any one of claims 1 to 3.

5. The nickel removal rate in the aforementioned refining process is 80% or more. The manufacturing method according to any one of claims 1 to 3.

6. The concentration of nickel in the second aqueous solution is 25 μg / kg or less, based on an aqueous solution in which the concentration of the alkali metal or alkaline earth metal is 12.8 mol / L. The manufacturing method according to any one of claims 1 to 3.

7. The first aqueous solution contains the alkali metal compound, The alkali metal compound comprises at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, and potassium carbonate. The manufacturing method according to any one of claims 1 to 3.

8. The concentration of the alkali metal compound and / or alkaline earth metal compound contained in the first aqueous solution is 25 to 52% by mass. The manufacturing method according to any one of claims 1 to 3.

9. The first aqueous solution or its precursor solution comes into contact with the inner surface of the apparatus for producing the alkali metal compound and / or the alkaline earth metal compound before the purification step. The manufacturing method according to any one of claims 1 to 3.

10. The inner surface of the manufacturing apparatus contains nickel, The manufacturing method according to claim 9.

11. The nickel contained in the first aqueous solution has not undergone at least one pretreatment selected from the group consisting of aggregation, precipitation, and deposition. The manufacturing method according to any one of claims 1 to 3.

12. The first aqueous solution substantially does not contain any agent for agglomerating, precipitating, or depositing the nickel. The manufacturing method according to any one of claims 1 to 3.

13. The aforementioned agent is at least one selected from the group consisting of a combination of hydrogen peroxide solution and an inorganic salt of a rare earth element, hypochlorous acid or its salt, sulfur compounds, chelating agents, polyaluminum chloride, and ammonium sulfate. The manufacturing method according to claim 12.

14. Alkali metal compounds exhibiting alkalinity or alkaline earth metal compounds exhibiting alkalinity, The number of particles with a particle size of 0.5 μm or larger contained in the alkali metal compound or the alkaline earth metal compound is 100 particles / mL or less, based on an aqueous solution in which the alkali metal or alkaline earth metal has a concentration of 1 mol / L. The concentration of nickel contained in the alkali metal compound or the alkaline earth metal compound is 10,000 μg / kg or less, based on an aqueous solution in which the alkali metal or alkaline earth metal concentration is 12.8 mol / L. Alkali metal compounds or alkaline earth metal compounds.

15. The alkali metal compound or alkaline earth metal compound is selected from the group consisting of potassium hydroxide, sodium hydroxide, and potassium carbonate. The alkali metal compound or alkaline earth metal compound according to claim 14.

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