Production method of lithium hydroxide

Abstract

To provide a method which enables inexpensive production with a high yield of lithium hydroxide with a low amount of impurities such as sodium from lithium-containing water including a lithium ion and a chloride ion.SOLUTION: A production method of lithium hydroxide includes: a crystallizing step of crystallizing lithium hydroxide (LiOH) from lithium-containing water including a lithium ion and a chloride ion; a solid-liquid separation step of performing solid-liquid separation treatment of concentrated liquid including the LiOH to obtain the LiOH as a solid product and filtrate; a carbonation step of producing lithium carbonate from the filtrate by carbonation; a lithium carbonate recovery step of evaporating at least a part of ammonia from a mixed liquid obtained in the carbonation step and performing solid-liquid separation treatment of the resultant treated liquid to obtain lithium carbonate as a solid product; a lithium hydroxide production step of converting the obtained lithium carbonate into LiOH followed by solid-liquid separation treatment to obtain an aqueous LiOH solution (1) as a liquid component; and a recrystallizing step of crystallizing LiOH from the aqueous solution (1).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing lithium hydroxide. [Background technology]

[0002] In recent years, there has been widespread research into recovering various valuable metals from waste materials such as lithium-ion batteries and circuit boards that have been discarded due to reasons such as the end of their product life or manufacturing defects.

[0003] In the lithium-ion battery, typical materials used for the positive electrode include lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, and lithium manganese oxide, the electrode current collector includes aluminum foil or copper foil, the electrolyte includes lithium hexafluorophosphate, and the battery outer can includes aluminum or iron. Furthermore, the wiring of the substrate is typically made of copper. Therefore, examples of valuable metals that can be recovered from waste materials such as lithium-ion batteries and substrates include cobalt, nickel, manganese, copper, lithium, aluminum, and iron. Various studies have been conducted to recover these metals at high yields and low cost.

[0004] The valuable metals recovered are highly valuable if they are obtained as highly pure substances. To obtain highly pure substances, a combination of various methods is required for separation. Generally speaking, recovery methods include dry processing, in which waste is placed in a furnace and melted at high temperatures to separate the valuable metals from slag, and wet processing, which uses methods such as acid, neutralization, and solvent extraction. Wet processing has the advantage of consuming less energy and being able to separate the valuable metals individually by using the right chemicals and conditions.

[0005] For example, Patent Document 1, which examines wet treatment of waste, describes focusing on cobalt, nickel, and manganese, and carrying out specific pre-neutralization steps and post-neutralization steps to obtain a neutralization residue containing these metals. Patent Document 2 describes that an aqueous solution containing sodium sulfate and lithium is treated using a bipolar electrodialysis device equipped with a cation exchange membrane, a bipolar membrane, and an anion exchange membrane to obtain an aqueous solution of sodium hydroxide containing lithium, and that the aqueous solution can be used as a pH adjuster.

[0006] Patent Document 3 describes a method for acid leaching and further processing black lump feed material containing materials liberated from within a lithium iron phosphate battery material, in which the pH is adjusted to 8 to 11 with calcium hydroxide in order to remove iron and phosphorus in the acid leachate as precipitates, and lithium is reacted with sodium carbonate to form lithium carbonate.

[0007] Patent Document 4 describes the use of oxalic acid treatment to reduce calcium in brine during the process of producing lithium hydroxide monohydrate using lithium-containing brine as a raw material. Patent Document 5 describes that while conventional methods for producing lithium hydroxide generally involve extracting lithium carbonate from lithium chloride contained in irrigation water, adding calcium hydroxide to produce lithium hydroxide, and further reducing impurities, there are limitations to the extent to which impurities can be reduced. After extensive investigation, the researchers came up with a new method of purifying lithium hydroxide (as an alkaline solution) by subjecting an aqueous lithium chloride solution obtained by extraction from lithium-containing ore with hydrochloric acid to bipolar electrodialysis. Patent Document 6 describes a step of causticizing lithium chloride with sodium hydroxide as one step in a method for producing lithium hydroxide. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2023-63319 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-171827 [Patent Document 3] Special Publication No. 2023-516663 [Patent Document 4] Special Publication No. 2011-518257 [Patent Document 5] Japanese Patent Application Laid-Open No. 2009-269810 [Patent Document 6] Special Publication No. 2018-500261 Summary of the Invention [Problem to be solved by the invention]

[0009] The leachate obtained by acid leaching waste materials such as lithium-ion batteries contains lithium ions, fluoride ions, anions (conjugate bases) derived from the acid used for leaching, and trace amounts of sodium ions.

[0010] Lithium is used in the production of lithium-ion batteries in the form of lithium compounds such as lithium hydroxide and lithium carbonate. When considering recovering lithium from treated water such as the leachate and reusing it as a material for lithium-ion batteries, battery-grade lithium compounds must be highly pure, and it is necessary to recover lithium by sufficiently removing components other than lithium.

[0011] Regarding the recovery of lithium, Patent Document 1 focuses on cobalt, nickel, and manganese. Regarding the recovery of lithium, Patent Document 1 describes a method of crushing lithium-ion battery waste, bringing the resulting granules into contact with water to dissolve the lithium, and then performing acid leaching. However, the amount of lithium dissolved by contacting the granules with water is small, with most of it transferring to the acid leachate. In other words, Patent Document 1 does not provide any substantial description of the recovery of lithium.

[0012] Patent Document 2 relates to a process using a bipolar electrodialysis device. Fluoride ions are contaminated in the acid leachate due to the electrolyte of a lithium-ion battery, etc. Through investigations by the inventors, it has been found that the above process cannot sufficiently separate the fluoride ions from the lithium.

[0013] Patent Document 3 describes converting lithium to lithium carbonate, but does not describe how to remove fluoride ions when the lithium contains them. Patent Document 4 does not specifically mention lithium recovery.

[0014] In light of the above, the present inventors have conducted extensive research with the aim of providing a method for obtaining a lithium-containing solution useful as a raw material for producing high-purity lithium compounds from water to be treated that contains lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and anions that are the conjugate bases of acids.

[0015] As a result, the present inventors have discovered a method for producing a raw material solution for producing a lithium compound by treating acidic water to be treated, which contains lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and at least one strong acid ion selected from the group consisting of sulfate ions, chloride ions, and nitrate ions, the method comprising the steps of: adding a sulfiding agent and a calcium compound to the water to be treated and adjusting the pH of the water to neutral or weakly alkaline to form solids; and then subjecting the water to solid-liquid separation to obtain treated liquid A. The inventors have invented a method for producing a raw material solution for producing a lithium compound, which comprises the steps of: Step 1; Step 2; adding an oxalate ion source to the treatment solution A to form a solid matter, and then subjecting the treatment solution A containing the solid matter to solid-liquid separation to obtain a treatment solution B; and Step 3; electrodialyzing the treatment solution B using an electrodialysis device equipped with a bipolar membrane having an anion exchange layer and a cation exchange layer, and a cation exchange membrane, to obtain an alkaline solution containing lithium ions and sodium ions that has permeated the cation exchange membrane, as a raw material solution for producing the lithium compound, and have filed a patent application (Japanese Patent Application No. 2023-188699).

[0016] Furthermore, in the invention of the aforementioned application, sulfuric acid is selected as the first choice of acid for leaching from the viewpoint of the chemical cost of the acid, but this generates a large amount of gypsum (mainly consisting of calcium sulfate) in the subsequent treatment, which must be disposed of as industrial waste, and the waste disposal costs can be high due to the amount of gypsum.

[0017] Therefore, the present inventors have conducted research into a process for obtaining a lithium-containing solution useful as a raw material for producing high-purity lithium compounds by acid leaching waste materials such as lithium ion batteries and treating the resulting leachate (containing lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and anions that are the conjugate bases of the acid) as treated water, with the aim of providing a process in which the amount of substances that can become waste materials is reduced compared to the inventions in the above-mentioned applications, as well as elemental technologies and related technologies that can be used in the process.

[0018] As a result, the present inventors have discovered a method for producing a raw material solution for producing a lithium compound by treating acidic water to be treated that contains lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and chloride ions, the method comprising the steps of: 1) adding a calcium compound to the water to be treated and making the pH of the water to be treated weakly alkaline to form solids; 2) subjecting the water to solid-liquid separation to obtain treated solution A; 3) adding an alkaline substance to treated solution A to make the pH of treated solution A alkaline to form solids; The inventors have invented a method for producing a raw material solution for producing a lithium compound, which comprises the steps of: Step 2: treating the treated solution B with an oxalate ion source and / or a carbonate ion source to form a solid, and then subjecting the treated solution B containing the solid to solid-liquid separation to obtain treated solution C; and Step 4: electrodialyzing the treated solution C with an electrodialysis device equipped with a bipolar membrane having an anion exchange layer and a cation exchange layer, and a cation exchange membrane, to obtain an alkaline solution containing lithium ions and sodium ions that has permeated the cation exchange membrane, as the raw material solution for producing the lithium compound, and have filed a patent application (Japanese Patent Application No. 2023-207257).

[0019] However, in the invention of the aforementioned patent application, lithium hydroxide is crystallized from a raw material solution for producing a lithium compound containing lithium ions and chloride ions by, for example, evaporating water to concentrate it, but the resulting concentrated solution contains a considerable amount of chloride ions derived from the hydrochloric acid used in the acid leaching. Because lithium chloride has high solubility, the concentrated solution contains lithium in the (ionized) form of lithium chloride.

[0020] Therefore, the invention of this patent application makes it difficult to increase the yield of lithium hydroxide, which is a very important factor for practical industrial application. Furthermore, with regard to the production of lithium hydroxide, the inventors have found through their studies that the method described in Patent Document 5 does not sufficiently separate chloride ions from lithium during bipolar electrodialysis, meaning that a certain amount of lithium chloride remains in the resulting alkaline solution. This has a negative impact on the yield of lithium hydroxide. In the examples of Patent Document 5, it is believed that lithium chloride is converted to lithium hydroxide using an anion exchange resin (OH column), but using an anion exchange resin to remove chloride ions increases the cost of the process.

[0021] Furthermore, in the method described in Patent Document 6, sodium is added to produce lithium hydroxide, resulting in a lithium hydroxide aqueous solution containing sodium, but it is difficult to separate the sodium from the solution. To separate the sodium, the invention in this document involves a complex and lengthy process in which sodium chloride is crystallized in the solution and separated by filtration, and then sodium hydroxide is added to the filtrate, sodium chloride is crystallized in the solution, and the filtrate is filtered and separated, repeating this process until lithium compounds contaminated in the sodium chloride are separated. In order to increase the yield of lithium hydroxide, the filtration and separation must be repeated many times. This increases the cost of the process.

[0022] In view of the above, an object of the present invention is to provide a method capable of producing lithium hydroxide containing a small amount of impurities such as sodium in a high yield and at low cost from lithium-containing water containing lithium ions and chloride ions to a certain degree or more as described above. [Means for solving the problem]

[0023] As a result of intensive investigations to solve the above-mentioned problems, the present inventors have found that lithium hydroxide with a small amount of impurities can be produced inexpensively and in high yield through the entire process by carrying out crystallization of lithium hydroxide from the lithium-containing water in the same manner as in the above-mentioned patent application, carbonating the obtained liquid component (containing lithium ions and chloride ions), separating chloride ions from lithium carbonate, which is a solid component, by carrying out solid-liquid separation treatment, and subsequently converting the lithium carbonate to lithium hydroxide, which is then subjected to crystallization again, thereby completing the present invention.

[0024] That is, the present invention is as follows.

[0025] [1] a crystallization step of crystallizing lithium hydroxide by evaporating water from lithium-containing water containing 2500 ppm or more of lithium ions and 1500 ppm or more of chloride ions to obtain a concentrated solution containing lithium hydroxide crystals; a solid-liquid separation step of subjecting the concentrated liquid to solid-liquid separation to obtain lithium hydroxide as a solid and a filtrate as a liquid component; a carbonation step of mixing the filtrate obtained in the solid-liquid separation step with ammonium carbonate and / or ammonium bicarbonate to obtain a mixed liquid containing lithium carbonate; a lithium carbonate recovery step of subjecting the mixed liquid obtained in the carbonation step to a treatment for evaporating at least a part of the ammonia to obtain a treated liquid, and subjecting the treated liquid to a solid-liquid separation treatment to obtain lithium carbonate as a solid; a lithium hydroxide production step in which the lithium carbonate obtained in the lithium carbonate recovery step is mixed with water and calcium hydroxide to produce lithium hydroxide and calcium carbonate, and then a solid-liquid separation treatment is performed to obtain a lithium hydroxide aqueous solution (1) as a liquid component; a recrystallization step of evaporating water from the lithium hydroxide aqueous solution (1) to crystallize lithium hydroxide; A method for producing lithium hydroxide, comprising:

[0026] [2] a crystallization step of crystallizing lithium hydroxide by evaporating water from lithium-containing water containing 2500 ppm or more of lithium ions and 1500 ppm or more of chloride ions to obtain a concentrated solution containing lithium hydroxide crystals; a solid-liquid separation step of subjecting the concentrated liquid to solid-liquid separation to obtain lithium hydroxide as a solid and a filtrate as a liquid component; a carbonation step in which the filtrate obtained in the solid-liquid separation step is brought into contact with carbon dioxide gas to produce lithium carbonate; a lithium carbonate recovery step of subjecting the liquid containing lithium carbonate obtained in the carbonation step to solid-liquid separation to obtain lithium carbonate as a solid; a lithium hydroxide production step in which the lithium carbonate obtained in the lithium carbonate recovery step is mixed with water and calcium hydroxide to produce lithium hydroxide and calcium carbonate, and then a solid-liquid separation treatment is performed to obtain a lithium hydroxide aqueous solution (1) as a liquid component; a recrystallization step of evaporating water from the lithium hydroxide aqueous solution (1) to crystallize lithium hydroxide; A method for producing lithium hydroxide, comprising:

[0027] [3] The method for producing lithium hydroxide according to [1] or [2], wherein the lithium-containing water has a lithium ion content of 18,000 ppm or less and a chloride ion content of 25,000 ppm or less.

[0028] [4] The method for producing lithium hydroxide according to any one of [1] to [3], wherein the lithium-containing water contains 3000 ppm or more of lithium ions, 3500 ppm or more of chloride ions, 20 ppm or more of sodium ions, and each of magnesium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions, and zinc ions is 10 ppm or less, and the calcium ion content is 150 ppm or less, and the lithium-containing water is an ammonium ion-removed solution obtained by removing at least a portion of ammonium ions from metal- and other-containing water containing 3000 ppm or more of ammonium ions.

[0029] [5] The metal-containing water A step A includes adding a calcium compound to acidic water to be treated that contains lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and chloride ions, and adjusting the pH of the water to be treated to 7.1 to 9.0 to form solid matter, and then subjecting the water to solid-liquid separation to obtain a treated liquid A; a step B of adding an alkaline substance to the treatment liquid A to adjust the pH of the treatment liquid A to 9.8 to 13.0 to form a solid, and then subjecting the treatment liquid A containing the solid to a solid-liquid separation treatment to obtain a treatment liquid B; a step C of adding at least one selected from the group consisting of ammonium carbonate, ammonium bicarbonate, and ammonium oxalate to the treatment liquid B to form a solid, and then subjecting the treatment liquid B containing the solid to solid-liquid separation to obtain a treatment liquid C; and step D of subjecting the treated liquid C to bipolar electrodialysis, In the bipolar electrodialysis, the treated liquid C is electrodialyzed using an electrodialysis device equipped with a bipolar membrane having an anion exchange layer and a cation exchange layer, and a cation exchange membrane, to obtain an alkaline liquid containing lithium ions, sodium ions, and ammonium ions that have permeated the cation exchange membrane. The method for producing lithium hydroxide according to any one of [1] to [4].

[0030] [6] The method for producing lithium hydroxide according to any one of [1] to [5], further comprising a step C' of filtering the treated liquid C through a nanofilter, and subjecting the obtained filtrate to a reverse osmosis membrane treatment to obtain a concentrated liquid, and the obtained concentrated liquid is subjected to the step D.

[0031] [7] The method for producing lithium hydroxide according to any one of [1] to [6], wherein the water to be treated is a leachate obtained by leaching with hydrochloric acid granules obtained by subjecting waste containing lithium ion batteries to a granulation process including a roasting step, a crushing step, and a magnetic separation step.

[0032] [8] The lithium hydroxide obtained in the solid-liquid separation step contains lithium carbonate, a carbonate conversion step in which the lithium hydroxide containing lithium carbonate is mixed with water, the resulting mixture is subjected to solid-liquid separation to obtain a lithium hydroxide aqueous solution (2) as a filtrate and lithium carbonate as a solid component, the lithium carbonate is mixed with water and calcium hydroxide to produce lithium hydroxide and calcium carbonate, and then solid-liquid separation is performed to obtain a lithium hydroxide aqueous solution (3) as a liquid component; The method for producing lithium hydroxide according to any one of [1] to [7], further comprising carrying out a second recrystallization step of evaporating water from the lithium hydroxide aqueous solution (2) and the lithium hydroxide aqueous solution (3) obtained in the carbonate content conversion step to crystallize lithium hydroxide.

[0033] [9] In the carbonate content conversion step, lithium hydroxide containing lithium carbonate and water are mixed with the lithium hydroxide aqueous solution (1) obtained in the lithium hydroxide production step, The method for producing lithium hydroxide according to [8], wherein the second recrystallization step also serves as the recrystallization step.

[0034]

[10] the concentrated liquid in which lithium hydroxide crystals have been produced, obtained in the second recrystallization step, is subjected to solid-liquid separation to obtain purified lithium hydroxide as a solid component and a purified lithium hydroxide filtrate as a liquid component; The method for producing lithium hydroxide according to [8] or [9], which comprises at least one of the following: The purified lithium hydroxide filtrate is recycled to the crystallization step. The purified lithium hydroxide filtrate is recycled to step D.

[0035]

[11] The method for producing lithium hydroxide according to

[10] , wherein the purified lithium hydroxide is washed with water and at least one of the following is carried out: · Recycle the water used for the water washing to the crystallization step. · Recycle the water used for the water washing to Step D.

Advantages of the Invention

[0036] According to the present invention, there is provided a method capable of producing lithium hydroxide with a small amount of impurities such as sodium at a high yield and at low cost from lithium-containing water containing lithium ions and chloride ions.

Brief Description of the Drawings

[0037] [Figure 1] FIG. 1 is a diagram showing an overview of a bipolar electrodialysis apparatus and electrodialysis used in a three-chamber method. [Figure 2] FIG. 2 is a diagram showing an overview of the process of the present invention. [Figure 3] FIG. 3 is a diagram showing an overview of the process implemented in the examples.

Embodiments for Carrying Out the Invention

[0038] Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments. In this specification, "X to Y" represents X or more and Y or less (X and Y are numerical values satisfying X < Y).

[0039] [Method for Producing Lithium Hydroxide] The present invention relates to a method capable of producing lithium hydroxide with a small amount of impurities such as sodium at a high yield and at low cost from lithium-containing water containing lithium ions and chloride ions. The above-mentioned lithium-containing water is typically generated by hydrochloric acid leaching of waste from lithium-ion batteries and further performing appropriate treatment. First, the generation of lithium-containing water will be described below.

[0040] <<Generation of Lithium-Containing Water>> <Production of Granular Material (Black Mass)> Lithium ion batteries are widely used in electronic devices such as mobile phones and personal computers, as well as in vehicles, and when these electronic devices are discarded due to the end of their battery life, manufacturing defects, or other reasons, waste containing lithium ion batteries is generated. In this invention, the widely used lithium ion batteries (waste) are the subject of treatment.

[0041] There are no particular limitations on the shape, structure, size, and material of lithium ion batteries (particularly lithium ion secondary batteries). Examples of lithium ion battery shapes include laminated, cylindrical, button, coin, square, and flat types. Examples of lithium ion battery forms include battery cells, battery modules, and battery packs. Here, a battery module refers to a plurality of battery cells, which are unit batteries, connected together and housed in a single housing, and a battery pack refers to a plurality of battery modules housed in a single housing. The battery pack may also include a controller or a cooling device.

[0042] An example of a lithium ion battery is one that includes a positive electrode, a negative electrode, a separator, an electrolytic solution containing an electrolyte and an organic solvent, and an outer container that is a battery case that houses the positive electrode, the negative electrode, the separator, and the electrolytic solution. Note that the lithium ion battery may be in a state in which the positive electrode, the negative electrode, etc. have fallen off.

[0043] Lithium-ion battery waste is heat-treated (roasted) at temperatures of, for example, 500 to 1000°C to convert valuable metals in the batteries, such as lithium and cobalt, into a form that is easily dissolved by acid. Organic matter, such as plastic, is also removed from the waste at this stage. A crushing process is then carried out, using, for example, an impact crusher (e.g., a sample mill, hammer mill, tornado mill, hammer crusher), to destroy the casing of the lithium-ion battery waste and granulate the waste. The crushed material may be sieved (classified), and in this case, a classified recovered material with a certain amount of aluminum removed is obtained at the bottom of the sieve. The crushing and sieving conditions can be appropriately selected from conventionally known conditions. A magnetic separation process is carried out on the crushed material and the classified recovered material, whereby cobalt, nickel, manganese, and other magnetic materials are separated from the crushed material / classified recovered material. This results in a granular material containing lithium (also known as black mass) as a non-magnetic material. The magnetic separation conditions can be appropriately selected from conventionally known conditions.

[0044] <Production of hydrochloric acid leachate> The resulting granules are leached with hydrochloric acid. This dissolves the various metals contained in the granules, and solid-liquid separation is performed on the negative electrode active material (graphite) and other materials. Through this process, a hydrochloric acid leachate of waste containing lithium-ion batteries is obtained. The conditions for the hydrochloric acid leaching can be appropriately selected from those known in the art. For example, a mixed solution obtained by adding hydrochloric acid to the granules at room temperature (the temperature of the solution may rise to about 60°C as the situation progresses) is stirred for 0.25 to 2 hours with the pH of the mixed solution adjusted to, for example, less than 1 (preferably 0.8 or less). Note that, to improve the leaching efficiency, the granules may be crushed before hydrochloric acid leaching.

[0045] <Composition of hydrochloric acid leachate> The chloride ion content in the hydrochloric acid leachate is, for example, 10,000 ppm or more. Although there is no particular upper limit to the content, the content is usually 200,000 ppm or less. The chloride ion content may be 25,000 to 120,000 ppm.

[0046] The hydrochloric acid leachate contains lithium ions. The content is, for example, 1000 ppm or more. The content may be 1500 ppm or more, or may be 2500 ppm or more. The upper limit of the content is not particularly limited, but is, for example, 15000 ppm.

[0047] The hydrochloric acid leachate contains sodium ions. Since lithium-ion batteries are basically made of materials that do not contain sodium, sodium is only mixed in as an impurity, and the sodium ion content in the treated water is usually 100 ppm or less. Note that this content is usually 1 ppm or more.

[0048] The hydrochloric acid leachate contains various metal ions other than lithium ions and sodium ions (hereinafter also referred to as "other metal ions") derived from the components of lithium ion batteries, such as the electrodes, electrolyte, and housing. Specific examples include magnesium ions, calcium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions, and zinc ions, and the hydrochloric acid leachate contains at least one of these ions. Among these, iron ions, aluminum ions, and nickel ions are often contained.

[0049] The total content of the magnesium ions, calcium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions and zinc ions in the hydrochloric acid leachate is, for example, 3000 ppm or more (usually 100000 ppm or less).

[0050] When the hydrochloric acid leachate contains these metal ions, the content of each ion is as follows: The magnesium ion content in the hydrochloric acid leachate is, for example, 15 ppm or more (usually 1000 ppm or less). The calcium ion content is, for example, 50 ppm or more (usually 3500 ppm or less). The aluminum ion content is, for example, 1500 ppm or more (usually 30000 ppm or less). The cobalt ion content is, for example, 150 ppm or more (usually 5000 ppm or less). The nickel ion content is, for example, 300 ppm or more (usually 15000 ppm or less). The manganese ion content is, for example, 300 ppm or more (usually 10000 ppm or less). The iron ion content is, for example, 5 ppm or more (usually 3000 ppm or less). The copper ion content is, for example, 500 ppm or more (usually 15000 ppm or less). The zinc ion content is, for example, 15 ppm or more (usually 1200 ppm or less).

[0051] Since fluorine-containing materials are widely used in the electrolytes and binders of lithium-ion batteries, the hydrochloric acid leachate contains fluoride ions. The fluoride ion content is, for example, 1000 ppm or more. Although there is no particular upper limit, the content is usually 12000 ppm or less.

[0052] The hydrochloric acid leachate may contain other components. An example of such a component is phosphate ions, which are typically contained in the positive electrode material. The content of phosphate ions in the hydrochloric acid leachate is, for example, 500 ppm or more. There is no particular upper limit to the content, but the content is usually 10,000 ppm or less.

[0053] Furthermore, the hydrochloric acid leachate often contains a trace amount of sulfuric acid. In such cases, the content of sulfate ions in the hydrochloric acid leachate is, for example, 80 ppm or more. Although there is no particular upper limit for this content, the content is usually 3000 ppm or less.

[0054] <Composition of hydrochloric acid leachate> The pH of the hydrochloric acid leachate is, for example, 0.1 to 2.5, and may be 0.3 to 2.0.

[0055] <Hydrochloric acid leachate treatment process> In order to produce lithium hydroxide from the hydrochloric acid leachate described above, various treatments are carried out. The treatment processes are described below. In the treatment processes, steps A, B, C, and D are carried out, and step C' may also be carried out optionally. In addition, step E is carried out in certain cases.

[0056] (Step A (First Reaction)) In step A, a calcium compound is added to the hydrochloric acid leachate to make the pH of the water to be treated slightly alkaline. In this solution, a wide variety of metal ions other than lithium ions and sodium ions (other metal ions) can be precipitated as solids. The calcium compound also reacts with fluoride ions and phosphate ions to form solid precipitates.

[0057] If the lithium ion content in the hydrochloric acid leachate exceeds 2000 ppm, precipitation may occur in each step of the leachate treatment process, and the amount of lithium ions captured by the separation means (filter paper, etc.) during solid-liquid separation may increase. Therefore, water may be added to the hydrochloric acid leachate to dilute the lithium ion content to 2000 ppm or less (usually 500 ppm or more) before carrying out step A.

[0058] Although the type of calcium compound used in step A is not particularly limited, slaked lime (calcium hydroxide) is preferred, because the addition of this compound can change the pH of the water to a weak alkaline state without adding any other alkaline substances.

[0059] In step A, the pH of the water to be treated is made weakly alkaline, preferably to a pH of 7.1 to 9.0.

[0060] By carrying out the above-described operations, a precipitate derived from other metal ions contained in the hydrochloric acid leachate is formed. This precipitate is subjected to solid-liquid separation. The means for this treatment are not particularly limited, and examples include filtration and filter press. A solid is recovered as a residue from the solid-liquid separation treatment.

[0061] By carrying out the step A described above, a treated liquid A (first post-reaction liquid) separated by solid-liquid separation treatment is obtained.

[0062] (Step B (Second Reaction)) In step B, an alkaline substance is added to the treated solution A obtained in step A to make the pH of the water to be treated alkaline. In this solution, a wide variety of metal ions other than lithium ions and sodium ions (other metal ions) can be further precipitated as solids.

[0063] The alkaline substance used in step B is a substance that dissolves in water and exhibits alkalinity, such as slaked lime, ammonia, and sodium hydroxide. Among these, slaked lime is preferred because it does not form an ammine complex with the transition metal to promote dissolution, and it does not add metals that are difficult to remove to the treatment solution A that is the target of treatment in step B.

[0064] The amount of alkaline substance used is determined by adding the alkaline substance until the pH of the water to be treated becomes alkaline.

[0065] In step B, the pH of treatment solution A is adjusted to alkaline by adding an alkaline substance. By adjusting the solution to this alkaline condition, other metal ions (those that remain and are not removed in step 1) are easily precipitated as hydroxides, etc. Note that alkaline is preferably a pH of 9.8 to 13.0.

[0066] By carrying out the operations described above, precipitates derived from other metal ions and the like contained in the treatment liquid A are generated. These precipitates are subjected to solid-liquid separation treatment. The means for this treatment are not particularly limited, and examples include filtration and filter press.

[0067] By carrying out the step B described above, a treated liquid B (second post-reaction liquid) separated by solid-liquid separation treatment is obtained.

[0068] (Step C (Third Reaction)) In step C, an oxalate ion source and / or a carbonate ion source is added to the treatment solution B obtained in step B. Calcium oxalate and calcium carbonate, which are produced by the reaction of oxalate ions and carbonate ions with calcium ions, have low solubility and readily precipitate, and can therefore be easily removed by solid-liquid separation.

[0069] In the oxalate ion source and carbonate ion source, counter cations other than protons may remain in the solution and become impurities, so oxalic acid and carbonate, in which the counter cation is a proton, and ammonium oxalate, ammonium carbonate, and ammonium bicarbonate, in which the counter cation is an ammonium ion (which is alkaline and becomes volatile ammonia), are preferred.

[0070] The amount of the oxalate ion source and / or carbonate ion source used is preferably 1 to 10 molar amounts relative to Ca, from the viewpoint of sufficiently precipitating calcium ions.

[0071] The reaction pH in step C (pH of the solution obtained by adding the oxalate ion source and / or carbonate ion source to treatment solution B) is, for example, 8 to 13. The reaction time is usually 5 minutes or more and 90 minutes or less.

[0072] The addition of the oxalate ion source and / or carbonate ion source causes calcium ions to form precipitates, and then solid-liquid separation is carried out to obtain treated liquid C. The specific means for the solid-liquid separation is the same as in the solid-liquid separation in step A.

[0073] By carrying out steps A to C, almost all metal ions except for lithium and sodium ions in the hydrochloric acid leachate, i.e., other metal ions, are removed, and most anion components are also removed except for chloride ions. As a result, lithium ions are dissolved in water in the form of salts with chloride ions (ionized). Because lithium chloride has high solubility, the recovery loss of lithium ions up to step C is minimized.

[0074] <Process C'> The treated liquid C obtained in step C may be subjected to nanofilter filtration and reverse osmosis membrane treatment (step C').

[0075] By nanofilter filtration, polyvalent ions other than lithium ions (and sodium ions) can be removed from treated liquid C (third post-reaction liquid).Then, to concentrate the resulting permeate, a reverse osmosis membrane (RO membrane) is used.

[0076] The nanofilter is typically a cross-flow filter equipped with a semipermeable membrane made of resin, and is configured to remove polyvalent ions. It is particularly effective in removing polyvalent ions and allowing Li to pass through, especially in the acidic range. Specific examples of nanofilters include commercially available polypiperazine nanofilters (e.g., NF270 manufactured by DOW Chemical) and polyamide nanofilters (e.g., NF90 manufactured by DOW Chemical). Among these, polypiperazine nanofilters are effective in removing polyvalent ions and allowing Li to pass through.

[0077] Furthermore, by adjusting the pH of treated liquid C (third post-reaction liquid) during nanofilter filtration to 1 to 11, particularly 1.2 to 4, it is possible to prevent the distribution of multivalent ions such as calcium ions into the permeate, recover high-purity Li in the permeate, and also separate the remaining CO2.

[0078] Subsequently, the permeate obtained by nanofilter filtration is subjected to reverse osmosis membrane treatment. This treatment is sufficient as long as it can concentrate the permeate, and any conventionally known cross-flow reverse osmosis membrane can be used without particular limitation. The pH of the permeate during reverse osmosis membrane treatment is not particularly limited, but may be, for example, in the range of pH 1 to 11.

[0079] <Process D> In step D, the treated liquid C obtained in step C or the concentrated liquid obtained in step C' is subjected to electrodialysis using a bipolar electrodialysis device. The details are as follows.

[0080] In bipolar electrodialysis, known bipolar electrodialysis devices can be used, and so-called two-compartment and three-compartment methods can be adopted. Here, the three-compartment method, which is also adopted in the examples described below, will be explained. In the three-compartment method, for example, a bipolar electrodialysis device 10 having the configuration shown in Figure 1 is used.

[0081] 1, an anode 11 is arranged on the far left, a left-end bipolar membrane 1 is arranged to its right, a left anion exchange membrane 2 is arranged to its right, a left cation exchange membrane 2' is arranged to its right, a central bipolar membrane 3 is arranged to its right, a right anion exchange membrane 4 is arranged to its right, a right cation exchange membrane 4' is arranged to its right, a right-end bipolar membrane 5 is arranged to its right, and a cathode 12 is arranged on the far right. Flow paths (1) to (4') are formed between these membranes.

[0082] When the bipolar electrodialysis device 10 is powered on, the treated water tank 6 supplies the treated liquid C obtained in step C or the concentrated liquid obtained in step C' (hereinafter also referred to as "treated liquid C, etc.") to the flow paths (2) and (4). In these flow paths, anions (chloride ions, etc.) in the concentrated liquid move toward the anode 11. Focusing on flow path (2), for example, anions pass through the left anion exchange membrane 2 and enter flow path (1), where they are absorbed from the left cation exchange layer 1b of the left bipolar membrane 1. + As a result, for example, hydrochloric acid is regenerated and recovered in the acid liquid tank 7.

[0083] The cations that have permeated the left cation exchange membrane 2' are transferred from the central anion exchange layer 3a of the central bipolar membrane 3 to the left cation exchange membrane 2', and the OH - is supplied to the flow path (2') and forms hydroxide with the cations. The liquid (alkaline liquid) flowing through the flow path (2') is then collected in the alkaline liquid tank 9.

[0084] Substances that have no charge do not permeate either the anion exchange membrane or the cation exchange membrane, but remain in the flow path to which they were originally supplied, and circulate between the flow path and the tank 6 for treated water.

[0085] 1 shows an example in which two sets of combinations of a left-end bipolar membrane 1, a left-side anion exchange membrane 2, and a left-side cation exchange membrane 2' are arranged, and a right-end bipolar membrane 5 is provided. However, there is no limit to the number of such combinations (membrane structures in which the three types of membranes are repeatedly arranged), and for example, the number of such combinations may be 10 to 200, and the right-end bipolar membrane 5 may be provided.

[0086] The conditions for the electrodialysis step are not limited. An example is as follows: Voltage of applied current in bipolar electrodialysis: 25~35V Current applied in bipolar electrodialysis: Maximum 4.4A Current application time: Change as appropriate depending on the desired lithium ion concentration in the alkaline solution and the amount of treatment solution C to be treated. Temperature at which bipolar electrodialysis is carried out (temperature of treatment liquid C, etc.): Taking into consideration the influence on various membranes such as anion exchange membranes used in this embodiment, it can be set to room temperature, for example, 2 to 40°C.

[0087] In the alkaline solution (also referred to as metal-containing water) obtained in step D, impurities other than lithium ions and sodium ions (and ammonium ions) are well reduced (other metal ions have been well reduced up to step C), and lithium ions and sodium ions are concentrated.

[0088] The alkaline solution obtained in step D, which contains mainly lithium ions and is substantially free of ammonia, can be used to produce battery-grade lithium hydroxide. This alkaline solution is useful as a raw material solution for producing lithium compounds, and can be used as lithium-containing water in the method for producing lithium hydroxide of the present invention. If the alkaline solution contains ammonium ions, these are removed in step E, which will be described next.

[0089] The composition of the alkaline solution containing the ammonium ions is, for example, as follows: The alkaline solution usually contains 3000 ppm or more of lithium ions (usually 12000 ppm or less). The alkaline solution usually contains 20 ppm or more of Na (usually 600 ppm or less). In the alkaline solution, the content of each of magnesium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions and zinc ions is, for example, 10 ppm or less. In the alkaline solution, the calcium ion content is usually 150 ppm or less (usually 5 ppm or more). In the alkaline solution, the content of fluoride ions is usually 30 ppm or less (usually 2 ppm or more). The alkaline solution usually contains 3500 ppm or more of chloride ions (usually 25000 ppm or less). In the alkaline solution, the content of phosphate ions is usually 10 ppm or less. In the alkaline solution, the content of sulfate ions is usually 100 ppm or less. The alkaline solution usually contains 3000 ppm or more of ammonium ions (the content is usually 60000 ppm or less).

[0090] <Process E> If chemicals that produce ammonium ions are used in steps B and C, the alkaline solution obtained in step D will contain ammonium ions (ammonia), which will be removed in step E (ammonia stripping).

[0091] Conventional methods can be used to remove ammonium ions. The alkaline substances in the alkaline solution are basically lithium hydroxide and ammonia. Because lithium hydroxide is a stronger alkali than ammonia (its aqueous solution is more alkaline), a high proportion of ammonia exists in the alkaline solution in a free form rather than an ion form, and it can be easily removed by volatilization simply by heating or reducing the pressure.

[0092] By carrying out ammonia stripping in step E, a treated liquid with a reduced ammonium ion content (also referred to as an ammonium ion-removed liquid) is obtained. If the alkaline liquid or ammonium ion-removed liquid obtained in steps D or E has a high calcium ion content, the alkaline liquid or the like may be passed through a chelating resin to remove the calcium ions. Examples of chelating resins include chelating resins having iminodiacetic acid as a functional group. It is also desirable to replace the cation moiety of the chelating resin with lithium ions so that lithium ions are not also removed by passing the liquid through the chelating resin.

[0093] <<Crystallization process>> <Composition of lithium-containing water> Fig. 2 is a diagram showing an outline of the process of the present invention after the crystallization step. The following description will be made with reference to this diagram. The alkaline solution obtained in step D when it is substantially free of ammonia, and the ammonium ion-removed solution obtained by treatment in step E (or the post-resin treatment solution obtained by further passing the solution through a chelating resin) can be used as lithium-containing water in the method for producing lithium hydroxide of the present invention. The specific composition of the lithium-containing water is as follows:

[0094] The content of ammonium ions in the lithium-containing water is, for example, 800 ppm or less, preferably 400 ppm or less, and is usually 5 ppm or more. The lithium ion content in the lithium-containing water is, for example, 2500 ppm or more (usually 30000 ppm or less), and may be 3500 to 18000 ppm. The sodium ion content in the lithium-containing water is, for example, 800 ppm or less. The sodium ion content is preferably 500 ppm or less, and more preferably 350 ppm or less. The content is usually 20 ppm or more. The contents of magnesium ions, calcium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions, and zinc ions in the lithium-containing water are, for example, 100 ppm or less, preferably 50 ppm or less, and more preferably 10 ppm or less, respectively. The content of fluoride ions in the lithium-containing water is, for example, 50 ppm or less, preferably 30 ppm or less, and more preferably 20 ppm or less. The content of chloride ions in the lithium-containing water is, for example, usually 1500 to 25000 ppm, and may be 4000 to 15000 ppm. The content of phosphate ions in the lithium-containing water is, for example, 300 ppm or less, preferably 100 ppm or less, and more preferably 20 ppm or less. The content of sulfate ions in the lithium-containing water is, for example, 200 ppm or less, preferably 100 ppm or less, and more preferably 70 ppm or less.

[0095] <Crystallization operation> Next, the specific crystallization procedure in the crystallization step will be described. As described above, the lithium-containing water contains lithium ions and has a small content of other impurities. The anions contained in the lithium-containing water are chloride ions and hydroxide ions supplied in step D, etc., with the latter being present in a significantly larger amount. For this reason, the pH of the lithium-containing water is alkaline, typically 10 or higher (typically 13 or lower).

[0096] When the water in this lithium-containing water is evaporated, lithium ions can be crystallized as lithium hydroxide, which is a compound with hydroxide ions, which are counter anions. Although the raw material solution also contains a certain amount of sodium ions, sodium hydroxide has high solubility and the amount of sodium ions is sufficiently small compared to the amount of lithium ions, so crystallization can be easily carried out under conditions where lithium hydroxide crystallizes but sodium hydroxide does not.

[0097] Specifically, for example, crystallization can be carried out using a known evaporation and concentration apparatus under the following conditions. Evaporation concentrator: Either a steam-heated type or a heat pump type concentrator can be used. Pressure inside the evaporator: 0.03 to 0.3 atm Heating temperature (temperature of heated raw material liquid): 35-70℃ Treatment time: Can be adjusted appropriately to achieve the desired amount of lithium hydroxide crystallized.

[0098] <<Solid-liquid separation process>> The concentrated liquid containing the crystallized lithium hydroxide obtained in the crystallization step is subjected to solid-liquid separation (for example, filtration or filter press). The resulting solid may be washed as needed. Washing may be with water or a separately prepared saturated aqueous solution of lithium hydroxide. The washed lithium hydroxide is then dried to obtain lithium hydroxide powder suitable for battery grade.

[0099] Specifically, the composition of the lithium hydroxide powder is as follows: The lithium content in the lithium hydroxide powder is, for example, 15 to 17 mass %. The sodium content in the lithium hydroxide powder is, for example, 500 ppm or less, and preferably 100 ppm or less. The lithium hydroxide powder contains, for example, 30 ppm or less, preferably 10 ppm or less, of each of iron, aluminum, nickel, copper, calcium, magnesium, cobalt, manganese, zinc, phosphoric acid, and ammonia. The potassium content in the lithium hydroxide powder is, for example, 30 ppm or less, and preferably 10 ppm or less. The fluorine content in the lithium hydroxide powder is, for example, 50 ppm or less, and preferably 10 ppm or less. The content of chloride ions in the lithium hydroxide powder is, for example, 100 ppm or less, preferably 20 ppm or less, and more preferably 5 ppm or less. The content of sulfur element in the lithium hydroxide powder is, for example, 80 ppm or less, and preferably 10 ppm or less. The content of phosphorus element in the lithium hydroxide powder is, for example, 80 ppm or less, and preferably 10 ppm or less. The content of boron element in the lithium hydroxide powder is, for example, 80 ppm or less, and preferably 10 ppm or less. The carbon element content in the lithium hydroxide powder is, for example, 1.2% by mass or less, and preferably 1.0% by mass or less. The balance of the lithium hydroxide powder is oxygen, hydrogen, and inevitable impurities.

[0100] On the other hand, with respect to the filtrate obtained by carrying out the solid-liquid separation treatment, the lithium-containing water subjected to the crystallization step contains a considerable amount of chloride ions, specifically, typically 1500 to 25000 ppm. Because the lithium-containing water contains a large amount of hydroxide ions, the main form of Li is lithium hydroxide, but a certain amount is present as lithium chloride. And because lithium chloride has a very high solubility, the filtrate contains lithium.

[0101] Specifically, the composition of the filtrate is as follows: The lithium ion content in the filtrate is, for example, 10,000 ppm or more (usually 150,000 ppm or less), and may be 20,000 to 70,000 ppm. The sodium ion content in the filtrate is, for example, 6000 ppm or less. The sodium ion content is preferably 5000 ppm or less, and more preferably 3500 ppm or less. The content is usually 500 ppm or more. The contents of magnesium ions, calcium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions, and zinc ions in the filtrate are, for example, 50 ppm or less, preferably 20 ppm or less, and more preferably 10 ppm or less, respectively. The fluoride ion content in the filtrate is, for example, 1000 ppm or less, preferably 500 ppm or less, and more preferably 200 ppm or less. The chloride ion content in the filtrate is, for example, 20,000 ppm or more (usually 200,000 ppm or less), and may be 30,000 to 150,000 ppm. The phosphate ion content in the filtrate is, for example, 1000 ppm or less, preferably 600 ppm or less, and more preferably 250 ppm or less. The content of sulfate ions in the filtrate is, for example, 1000 ppm or less, preferably 600 ppm or less, and more preferably 250 ppm or less.

[0102] The ratio of the content of lithium ions to the content of chloride ions in the filtrate (Li / Cl) is, for example, 0.2 to 1.

[0103] As explained above, since the filtrate contains a certain amount of lithium ions, if the process is limited to the solid-liquid separation step, the lithium ions transferred to the filtrate side will be lost, and the production yield of lithium hydroxide from lithium-containing water will not be satisfactory. Therefore, in the present invention, further steps such as a carbonation step described below are carried out to increase the yield.

[0104] <<Carbonation process>> In the method for producing lithium hydroxide of the present invention, a carbonation step is carried out. In one carbonation method, the filtrate as the liquid component obtained in the solid-liquid separation step is mixed with ammonium carbonate and / or ammonium bicarbonate to carbonate the lithium contained in the filtrate. In this case, the amount of ammonium carbonate and / or bicarbonate used is, for example, 0.45 to 1.8 mol in total per 1 mol of lithium.

[0105] In another carbonation method, the filtrate obtained in the solid-liquid separation step is contacted with carbon dioxide gas. In this case, an excess amount of carbon dioxide gas is blown into the filtrate to ensure complete carbonation. Because the filtrate is alkaline, the carbon dioxide blown into the filtrate exists in the form of ions, which may be difficult to remove. For this reason, it is preferable to use ammonium carbonate and / or ammonium bicarbonate in the carbonation step.

[0106] In the above two carbonation methods, when the solids are washed with water in the solid-liquid separation step, lithium hydroxide may be dissolved in the wash water. Therefore, in order to increase the yield of lithium hydroxide, the wash water may be combined with the filtrate and the resulting mixed liquid may be subjected to the carbonation step. Furthermore, both the filtrate and the mixed liquid contain lithium hydroxide as the main solute and are therefore weakly alkaline to alkaline. When the above method using ammonium carbonate or the like is adopted, the pH can be increased to about 10 or higher by adding a small amount of an alkaline substance to the liquid, thereby facilitating the volatilization of ammonia from the liquid.

[0107] <<Lithium carbonate recovery process>> The liquid containing lithium carbonate obtained in the carbonation step is subjected to solid-liquid separation to recover lithium carbonate. Before the solid-liquid separation, the liquid may be heated and concentrated to adjust the liquid volume. If the liquid contains ammonia (ammonium ions), a certain amount of ammonia will evaporate during this heating and concentration. The heating and concentration method is not particularly limited, but for example, it is as follows. Evaporation concentrator: Either a steam-heated type or a heat pump type concentrator can be used. Pressure inside the evaporator: 0.03 to 0.3 atm Heating temperature (temperature of heated lithium carbonate-containing liquid): 35 to 70°C Processing time: Can be adjusted to achieve the desired volume of liquid.

[0108] After the heating and concentration as necessary, the liquid containing lithium carbonate is subjected to solid-liquid separation (for example, filtration or filter press) to obtain lithium carbonate as a solid. At this time, chloride ions contained in the lithium carbonate-containing water are present in the filtrate, and lithium and chloride ions are separated in this step. Most sodium ions also migrate to the filtrate. Furthermore, if the liquid containing lithium carbonate contains ammonia (ammonium ions), this is also separated into the filtrate by the solid-liquid separation. In this way, in the present invention, chloride ions and ammonia can be separated from lithium by conventionally known, inexpensive processes of carbonation and solid-liquid separation using inexpensive chemicals.

[0109] <<Lithium hydroxide production process>> Next, lithium carbonate is converted to lithium hydroxide. Specifically, the lithium carbonate obtained in the lithium carbonate recovery step is mixed with water and calcium hydroxide to produce lithium hydroxide (and calcium carbonate). The amount of calcium hydroxide used is preferably 50 to 150 parts by mass per 100 parts by mass of lithium carbonate so that it reacts sufficiently with carbonate ions and so that calcium ions do not remain in the liquid in excess.

[0110] After producing lithium hydroxide and calcium carbonate, a solid-liquid separation process (e.g., filtration or filter press) is performed on the mixture containing them. Although the solubility of lithium hydroxide is not that high, a certain proportion of lithium is recovered in the initial crystallization step. Furthermore, the solubility of calcium carbonate is much lower than that of lithium hydroxide. Therefore, by adjusting the amount of water, it is possible to transfer substantially all of the lithium without transferring calcium carbonate to the filtrate. In other words, the solid-liquid separation process allows the lithium hydroxide aqueous solution (1) to be obtained with a high lithium recovery rate. The calcium carbonate obtained as a solid is a by-product of the lithium hydroxide production method of the present invention and can be sold, for example.

[0111] To more thoroughly remove calcium ions from the lithium hydroxide aqueous solution obtained by the solid-liquid separation treatment, the aqueous solution may be passed through a chelating resin to remove calcium ions. Examples of chelating resins include chelating resins having iminodiacetic acid as a functional group. It is also desirable to replace the cation moiety of the chelating resin with lithium ions so that lithium ions are not also removed by passing the solution through the chelating resin.

[0112] The specific composition of the lithium hydroxide aqueous solution (1) obtained in the lithium hydroxide production step described above is as follows. The lithium ion content in the filtrate is, for example, 3000 ppm or more (usually 80000 ppm or less), and may be 5000 to 30000 ppm. The sodium ion content in the filtrate is, for example, 150 ppm or less. The sodium ion content is preferably 100 ppm or less, and more preferably 50 ppm or less. The content is usually 1 ppm or more. The contents of magnesium ions, calcium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions, and zinc ions in the filtrate are, for example, 30 ppm or less, preferably 10 ppm or less, and more preferably 5 ppm or less, respectively. The fluoride ion content in the filtrate is, for example, 100 ppm or less, preferably 50 ppm or less, and more preferably 20 ppm or less. The chloride ion content in the filtrate is, for example, 500 ppm or less, preferably 300 ppm or less, and more preferably 120 ppm or less. The phosphate ion content in the filtrate is, for example, 60 ppm or less, preferably 30 ppm or less, and more preferably 20 ppm or less. The content of sulfate ions in the filtrate is, for example, 400 ppm or less, preferably 200 ppm or less, and more preferably 100 ppm or less.

[0113] The ratio of the content of lithium ions to the content of chloride ions in the filtrate (Li / Cl) is 100 to 1000, for example.

[0114] <<Recrystallization process>> The lithium hydroxide aqueous solution (1) obtained in the lithium hydroxide production step described above has few impurities and contains substantially no metal ions other than lithium, and also contains only trace amounts of anions other than hydroxide ions.

[0115] Therefore, in the present invention, lithium hydroxide with a small amount of impurities can be crystallized by simply evaporating water from the lithium hydroxide aqueous solution (1) (recrystallization step). As a specific operation of the recrystallization step, for example, water is evaporated using a known evaporation concentration apparatus under the following conditions. Evaporation concentrator: Either a steam-heated type or a heat pump type concentrator can be used. Evaporator internal pressure: 0.03 to 0.95 atm Heating temperature: 35~95℃ Treatment time: Can be adjusted appropriately to achieve the desired amount of lithium hydroxide crystallized.

[0116] The resulting concentrated liquid containing lithium hydroxide crystals is subjected to solid-liquid separation (for example, filtration or filter press), and then washed with water and dried as necessary to obtain lithium hydroxide powder.

[0117] The lithium hydroxide obtained by carrying out the crystallization step or the lithium hydroxide obtained by carrying out the recrystallization step described above may be recrystallized to obtain a lithium hydroxide powder with even higher purity.

[0118] <<Carbonate conversion process>> In the solid-liquid separation step, lithium hydroxide powder is obtained as a solid content, but a part of the lithium hydroxide is converted to lithium carbonate during handling (often carried out in the air) in various processes up to obtaining this. In order to obtain lithium hydroxide in high yield, it is desirable to convert this lithium carbonate remaining in the lithium hydroxide to lithium hydroxide.

[0119] In the present invention, the lithium hydroxide containing lithium carbonate is mixed with water to obtain a mixed solution. Since lithium hydroxide has a higher solubility than lithium carbonate, lithium hydroxide dissolves but lithium carbonate does not. The amount of water used is such that the lithium hydroxide and lithium carbonate are separated into a liquid phase and a solid phase.

[0120] The resulting mixture is then subjected to solid-liquid separation (for example, filtration or filter press) to obtain a lithium hydroxide aqueous solution (2) as a liquid component and lithium carbonate as a solid component. This lithium carbonate is mixed with water and calcium hydroxide to produce lithium hydroxide (and calcium carbonate), similar to the lithium hydroxide production step described above. Since lithium hydroxide exists in the liquid phase and calcium carbonate exists in the solid phase, the resulting mixture is subjected to solid-liquid separation to obtain a lithium hydroxide aqueous solution (3). To more thoroughly remove calcium ions from the lithium hydroxide aqueous solution (3), the aqueous solution may be passed through a chelating resin, such as a chelating resin having iminodiacetic acid as a functional group.

[0121] <<Second recrystallization step>> In this step, lithium hydroxide is crystallized by evaporating water from the lithium hydroxide aqueous solutions (2) and (3) obtained in the carbonate content conversion step. As a specific operation for crystallization, for example, water is evaporated using a known evaporation concentration apparatus under the following conditions. Evaporation concentrator: Either a steam-heated type or a heat pump type concentrator can be used. Evaporator internal pressure: 0.03 to 0.95 atm Heating temperature: 35~95℃ Treatment time: Can be adjusted appropriately to achieve the desired amount of lithium hydroxide crystallized.

[0122] The above crystallization process yields a concentrated solution containing lithium hydroxide crystals. This concentrated solution is subjected to solid-liquid separation (e.g., filtration or filter press), and optionally washed with water and dried to obtain purified lithium hydroxide powder. This powder and the lithium hydroxide powder obtained by the recrystallization process can meet the requirements for battery grade.

[0123] Specifically, the composition of the lithium hydroxide powder is as follows: The lithium content in the lithium hydroxide powder is, for example, 15 to 17 mass %. The sodium content in the lithium hydroxide powder is, for example, 500 ppm or less, and preferably 100 ppm or less. The lithium hydroxide powder has a magnesium ion, calcium ion, aluminum ion, cobalt ion, nickel ion, manganese ion, iron ion, copper ion, zinc ion, potassium ion, fluoride ion, chloride ion, phosphorus, sulfur, boron, and carbon content of, for example, 30 ppm or less, preferably 10 ppm or less, respectively.

[0124] On the other hand, the filtrate obtained by carrying out the solid-liquid separation treatment (purified lithium hydroxide filtrate) is an aqueous lithium hydroxide solution containing lithium hydroxide and containing few other impurities. By circulating this to an appropriate step in the process of the present invention, lithium loss can be further reduced. Examples of steps to which the filtrate is circulated include a crystallization step (in which the purified lithium hydroxide filtrate is subjected to a crystallization operation such as evaporation and concentration) and step D (in which the purified lithium hydroxide filtrate is introduced into a tank 6 for treated water and subjected to bipolar electrodialysis).

[0125] When the solid content is washed with water in the solid-liquid separation treatment, lithium hydroxide may be dissolved in the wash water (purified lithium hydroxide wash solution), and therefore, in order to increase the lithium hydroxide yield, it is preferable to circulate the wash solution to the crystallization step or step D, similarly to the purified lithium hydroxide filtrate. From the viewpoint of simplifying the equipment and reducing equipment costs, it is preferable to circulate the purified lithium hydroxide wash solution and the purified lithium hydroxide filtrate together in the same step. Furthermore, since the wash solution and the filtrate are aqueous lithium hydroxide solutions with low impurities, circulating them to upstream steps is unlikely to result in the accumulation of impurities.

[0126] Furthermore, the purified lithium hydroxide cleaning solution and the purified lithium hydroxide filtrate are aqueous lithium hydroxide solutions containing few impurities and a certain concentration of lithium. However, these solutions may be further reduced in impurities to produce even higher-purity lithium hydroxide. Examples of methods for reducing impurities include electrodialysis using an apparatus equipped with a lithium ion conductive electrolyte membrane with small lattice defect sites and an electrode made of a porous membrane disposed on the electrolyte membrane. Details of this method are described in Japanese Patent Application Laid-Open Nos. 2015-34315 and 2019-141807. This method provides an aqueous lithium hydroxide solution with further reduced impurities, which may then be subjected to a recrystallization step or a second recrystallization step.

[0127] <Use as a second recrystallization step> The lithium hydroxide aqueous solution (1) obtained in the lithium hydroxide production step is crystallized in a recrystallization step separate from the second recrystallization step as described above. From the viewpoint of reducing the number of facilities for performing recrystallization and reducing facility costs, it is preferable that the lithium hydroxide aqueous solution (1) be combined with any of the steps up to the second recrystallization step. In this case, the second recrystallization step also serves as the recrystallization step (both steps can be performed in a single step).

[0128] Since this can also lead to a reduction in the amount of water used in the carbonate content conversion step, it is preferable to combine the lithium hydroxide aqueous solution (1) with the carbonate content conversion step. More specifically, it is preferable to mix, in the carbonate content conversion step, lithium hydroxide containing lithium carbonate and water with the lithium hydroxide aqueous solution (1) obtained in the lithium hydroxide production step. [Example]

[0129] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. Furthermore, the following comparative examples do not represent conventional examples.

[0130] In the following examples and comparative examples, various measurements were carried out as follows. Metal ion content: Measured using an ICP optical emission spectrometer SPS-5100 manufactured by Hitachi High-Tech Science and an ICP mass spectrometer Agilent 7900 ICP-MS manufactured by Agilent Technologies. Na ion content: Measured using a polarized Zeeman atomic absorption spectrophotometer ZA3300 manufactured by Hitachi High-Tech Science. pH: Measured at 25°C using a pH meter and electrode HORIBA D-73. Ammonium ion concentration: Measured using a Tosoh IC-8100EX ion chromatograph. Fluoride ion concentration: Measured using a Tosoh IC-8100EX ion chromatograph. Chloride ion concentration: Measured using a Tosoh IC-8100EX ion chromatograph. Phosphate ion concentration: Measured using a Tosoh IC-8100EX ion chromatograph. Sulfate ion concentration: Measured using a Tosoh IC-8100EX ion chromatograph. Phosphorus concentration: Measured using Agilent 5110 ICP-OES (Agilent Technologies, Inc.). Sulfur concentration: Measured using an Agilent 5110 ICP-OES (Agilent Technologies, Inc.). Carbon concentration: Measured using a carbon-sulfur analyzer (LECO CS844 model, non-diffusive infrared absorption method). Boron concentration: Measured using an ICP-AES device (SPECTRO Analytical Instruments GmbH, SPECTRO BLUE). Electrical resistance: Equilibrated in 0.5 mol / L saline and measured at 25°C using an alternating current. ·EC (electrical conductivity): Measured using an EC meter and electrode TOA DKK CM-31P.

[0131] [Example 1] <Production of hydrochloric acid leachate> Lithium-ion batteries were incinerated, crushed, and magnetically separated. 150 g of the remaining black mass (non-magnetic material) was crushed by hammering. 250 mL of pure water was then added, followed by 145 mL of 37% by mass hydrochloric acid. This solution (pH: 0.5) was stirred at 20-60°C for 0.5 hours (starting from room temperature, the temperature rose to 60°C due to heat of neutralization. The temperature then naturally cooled to 20°C). Pure water was added to bring the volume to 1 L, and solid-liquid separation was carried out.

[0132] <Step A (First Reaction)> The hydrochloric acid leachate obtained above was mixed with another hydrochloric acid leachate obtained by leaching another black mass with hydrochloric acid in the same manner as above. The resulting mixed solution (pH: 0.5) was diluted four times with pure water and then adjusted to pH 7.5 with hydrated lime. This solution was stirred for 0.5 hours, resulting in the formation of solids. The leachate containing the solids was subjected to solid-liquid separation using a filter press to obtain treated solution A.

[0133] <Step B (Second Reaction)> Slaked lime slurry was added to treated liquid A to adjust the pH to 10.5. After stirring this liquid for 60 minutes, the precipitate was filtered using a bag filter to obtain treated liquid B as a filtrate.

[0134] <Step C (Third Reaction)> Ammonium carbonate was added to treatment solution B to a concentration of 20 g / L, and the mixture was stirred. The amount of ammonium carbonate used was 2 molar times the amount of calcium ions in treatment solution B. After 60 minutes of stirring, the pH of the solution was 9.3. After the stirring, the precipitate was filtered off using a filter press, and treatment solution C was obtained as a filtrate.

[0135] The compositions of the treatment solutions A to C obtained in the above steps are shown in Table 1 below. [Table 1]

[0136] <Process C' (nanofilter filtration and RO (reverse osmosis) treatment)> The above steps up to step C were carried out on multiple black masses, yielding a total of 40 L of treated liquid C. These were combined, and the pH was 9. To this liquid was added a 37% by mass aqueous solution of hydrochloric acid to adjust the pH to 2.5. This liquid was treated with a Dow Chemical NF270-4040 membrane (cross-flow nanofilter). The separation operation was carried out by operating the device at a constant operating pressure of 1 MPa, and the liquid was separated into a permeate and a concentrate.

[0137] The permeate obtained by the nanofilter filtration was treated with a Dow Chemical SW30-4040 (reverse osmosis membrane). The separation operation was carried out by operating the device at a constant operating pressure of 6 MPa, and the permeate and concentrated liquid were separated.

[0138] <Process D (bipolar electrodialysis)> Eight liters of the concentrate obtained by RO treatment was fed to a bipolar electrodialysis device (Astrom, EX3B) shown in Figure 1. The bipolar membrane was Astrom BP1-EX, the cation exchange membrane was Astrom CMB, and the anion exchange membrane was Astrom AHA (electrical resistance 4.1 Ω cm). 2 Ten anion-exchange membranes and ten cation-exchange membranes, and eleven bipolar membranes were used, with the anion-exchange membrane, cation-exchange membrane, and bipolar membrane repeating ten times (the cation-exchange membrane and the anion-exchange layer of the bipolar membrane faced each other). The area of ​​the electrodialysis membrane was 0.055 m 2 is.

[0139] Initially, 8 L of the concentrated solution was added to the tank for treated water, 1.5 L of pure water to the acid tank, and 2 L of pure water to the alkali recovery tank. The applied voltage for the electrodialysis operation was kept constant at 35 V. The current value was automatically controlled within the range of 0 to 4.4 A. The treatment time was 8.6 hours. The desalination operation continued until the electrical conductivity of the tail solution (the liquid in the tank for treated water) became less than 0.5 mS / cm.

[0140] The compositions of the alkaline and acid solutions obtained by the bipolar electrodialysis described above are shown in Table 2 below, along with the composition of the concentrated solution obtained by RO treatment. [Table 2]

[0141] <Step E (ammonia stripping and chelating resin treatment)> 1.3 L of the recovered alkaline solution obtained in step D was fed to a low-temperature, high-vacuum ammonia removal apparatus. This apparatus consisted of a reaction vessel fitted with an agitator blade, connected in this order via piping to a drain pod, an NaOH scrubber (for ammonia capture), a cooler, and a diaphragm-type vacuum pump (DIVAC, 1.2 L). The vacuum pump was used to reduce the pressure inside the reaction vessel (in which the alkaline solution was charged). The ammonia removal operation was automatically controlled at a stripping temperature of 50°C and a vacuum pressure of 50 hPa. The entire 1.0 L of the resulting stripped solution (ammonium ion-removed solution) was passed through a Li-type chelating resin, KILEST, KILESPAR CH112, to remove metal ions other than alkali metals remaining in the stripped solution.

[0142] The compositions of the stripping treatment solution and the post-chelating resin treatment solution obtained by the above operations are shown in Table 3 below. [Table 3]

[0143] <Crystallization process> The process for producing lithium hydroxide according to the present invention carried out in this example is shown in FIG. 3 as a flow diagram of the process from the crystallization step onwards. The above steps up to step E were repeated for multiple black masses, and the resulting post-chelating resin treatment liquid was brought to a total of 11.6 L. This was fed into the same low-temperature, high-vacuum ammonia removal apparatus as above. From the liquid volume and lithium concentration, it was calculated that the post-chelating resin treatment liquid contained 72 g of lithium. The apparatus was automatically controlled to an evaporation temperature of 60°C and a vacuum pressure of 50 hPa, and evaporation and concentration were carried out. This allowed lithium hydroxide to crystallize.

[0144] If cloudiness occurred during the evaporation concentration, the liquid being concentrated (concentrated slurry) was extracted and subjected to sedimentation, and the supernatant water was returned to the evaporation concentration apparatus and evaporated again. The precipitate obtained by sedimentation was finally combined with the concentrated liquid obtained by evaporation concentration, in which lithium hydroxide crystals had formed.

[0145] <Solid-liquid separation process> The concentrated solution from which lithium hydroxide crystallized and the precipitate obtained by settling were combined, and the lithium hydroxide crystals were recovered by suction filtration. The crystals were washed once with 200 mL of pure water and dried under reduced pressure in a nitrogen atmosphere to obtain crude lithium hydroxide. The crude lithium hydroxide was dissolved in pure water, and the composition of the resulting solution was determined. The amount of lithium in the crude lithium hydroxide was found to be 59 g. Impurities in crude lithium hydroxide can be further reduced by, for example, recrystallization. The amount of chlorine in the crude lithium hydroxide was calculated from the composition and found to be 3500 ppm. Furthermore, since the solution after the chelating resin treatment contained 72 g of lithium, stopping the lithium hydroxide recovery process at this point would result in a loss of 13 g of lithium (18% of the original amount).

[0146] <Carbonation process> 200 mL of the pure water (crude LiOH washing solution) used to wash the crystallized lithium hydroxide was combined with 250 mL of the filtrate (crude LiOH filtrate) obtained by suction filtering the concentrated solution. 250 g of ammonium carbonate was added to this mixture, and the pH was adjusted to 10 with sodium hydroxide. The resulting mixture was stirred. As a result, lithium carbonate precipitated.

[0147] <Lithium carbonate recovery process> The mixed liquid containing the precipitate of lithium carbonate obtained above was heated and concentrated at 60°C and 50 hPa using a low-temperature, high-vacuum ammonia removal apparatus to reduce the liquid volume, and the mixed liquid after the volume reduction was subjected to solid-liquid separation treatment. The obtained solid was washed with warm water to obtain 86 g of lithium carbonate powder.

[0148] <Lithium hydroxide production process> The lithium carbonate powder and 85 g of slaked lime were repulped in 1.5 L of water and stirred. The resulting mixture was subjected to solid-liquid separation to obtain calcium carbonate as a solid, and a filtrate containing dissolved lithium hydroxide was obtained. The filtrate was passed through a Li-type chelating resin (Killespearl CH112) manufactured by Chelest, to remove metal ions other than alkali metals remaining in the filtrate. The composition of the resulting chelating resin-treated solution (LiOH aqueous solution (1)) was measured, and it was found that the solution (1.4 L) contained 13 g of lithium.

[0149] The compositions of the filtrate (crude LiOH filtrate) obtained in the solid-liquid separation step and the chelating resin treatment liquid (aqueous LiOH solution (1)) obtained in the lithium hydroxide production step are shown in Table 4 below. [Table 4]

[0150] It can be seen that by carrying out the carbonation step, lithium carbonate recovery step, and lithium hydroxide production step, it was possible to remove substantially all of the chlorine from the crude LiOH filtrate that contained a large amount of chlorine.

[0151] <Carbonate conversion process> Due to contact with the atmosphere in the above process C, the carbonation process, and various other processes, some of the lithium hydroxide becomes lithium carbonate. This lithium carbonate was converted to lithium hydroxide. Specifically, the process is as follows.

[0152] The crude lithium hydroxide obtained in the solid-liquid separation step and the chelating resin-treated liquid (1.4 L) obtained in the lithium hydroxide production step were mixed, and 1 L of pure water was further added. The resulting mixture was subjected to solid-liquid separation treatment (filtration).

[0153] The composition of the resulting liquid component (LiOH aqueous solution (2): 2.8 L) was determined, and it was found that the component contained 67 g of Li. Separately, 24 g of the solid obtained from the solid-liquid separation treatment was repulped in 0.5 L of purified water with 24 g of slaked lime, and the mixture was stirred. The resulting mixture was subjected to solid-liquid separation treatment to obtain calcium carbonate as a solid, and a filtrate containing dissolved lithium hydroxide was obtained. The filtrate was passed through a Li-type chelating resin, KILEST PEARL CH112, manufactured by KILEST, to remove metal ions other than alkali metals remaining in the filtrate. The composition of the resulting lithium hydroxide aqueous solution (3) was determined, and it was found that the solution (0.5 L) contained 3.9 g of lithium.

[0154] <Second recrystallization step (also serves as a recrystallization step)> The LiOH aqueous solution (2) (2.8 L) obtained above and the lithium hydroxide aqueous solution (3) were combined. The composition of the obtained lithium hydroxide-containing solution was determined, and it was found to contain 71 g of lithium. The lithium hydroxide-containing solution was fed to a vacuum evaporation concentration apparatus (EYELA NVC-2000) and evaporated and concentrated under automatic control at an evaporation temperature of 60°C and a vacuum pressure of 90 kPa. This allowed lithium hydroxide to crystallize.

[0155] In the evaporation and concentration, if cloudiness occurred, the liquid being concentrated (concentrated slurry) was extracted and subjected to sedimentation, and the supernatant water was returned to the evaporation and concentration apparatus, and evaporation and concentration was carried out again. Finally, the precipitate obtained by sedimentation was combined with the concentrated liquid obtained by evaporation and concentration, in which lithium hydroxide crystals had formed.

[0156] The concentrated solution from which lithium hydroxide crystallized and the precipitate obtained by settling were combined, and the lithium hydroxide crystals were recovered by suction filtration. The crystals were washed once with 400 mL of pure water and dried under reduced pressure in a nitrogen atmosphere to obtain purified lithium hydroxide powder. A composition analysis of the purified lithium hydroxide revealed that the amount of lithium in the purified lithium hydroxide was 54 g. The results of the composition analysis are shown in Table 5 below.

[0157] [Table 5]

[0158] The pure water used for the washing (which had come into contact with the lithium hydroxide crystals) was referred to as the purified lithium hydroxide washing solution, and its composition was determined. The composition of the filtrate obtained by the suction filtration (purified lithium hydroxide filtrate) was also determined. The results are shown in Table 6 below.

[0159] [Table 6]

[0160] From these results, it was found that the purified lithium hydroxide filtrate contained 8 g of Li, and the purified lithium hydroxide washings contained 10 g of Li. That is, together with the fact that the amount of lithium in the purified lithium hydroxide was 54 g, there was essentially no loss of Li in carrying out the above process, considering the crystallization step as the start.

Claims

1. a crystallization step of crystallizing lithium hydroxide by evaporating water from lithium-containing water containing 2500 ppm or more of lithium ions and 1500 ppm or more of chloride ions to obtain a concentrated solution containing lithium hydroxide crystals; a solid-liquid separation step of subjecting the concentrated liquid to solid-liquid separation to obtain lithium hydroxide as a solid and a filtrate as a liquid component; a carbonation step of mixing the filtrate obtained in the solid-liquid separation step with ammonium carbonate and / or ammonium bicarbonate to obtain a mixed liquid containing lithium carbonate; a lithium carbonate recovery step of subjecting the mixed liquid obtained in the carbonation step to a treatment for evaporating at least a part of the ammonia to obtain a treated liquid, and subjecting the treated liquid to a solid-liquid separation treatment to obtain lithium carbonate as a solid; a lithium hydroxide production step of mixing the lithium carbonate obtained in the lithium carbonate recovery step with water and calcium hydroxide to produce lithium hydroxide and calcium carbonate, followed by solid-liquid separation to obtain a lithium hydroxide aqueous solution (1) as a liquid component; a recrystallization step of evaporating water from the lithium hydroxide aqueous solution (1) to crystallize lithium hydroxide; A method for producing lithium hydroxide, comprising:

2. a crystallization step of crystallizing lithium hydroxide by evaporating water from lithium-containing water containing 2500 ppm or more of lithium ions and 1500 ppm or more of chloride ions to obtain a concentrated solution containing lithium hydroxide crystals; a solid-liquid separation step of subjecting the concentrated liquid to solid-liquid separation to obtain lithium hydroxide as a solid and a filtrate as a liquid component; a carbonation step in which the filtrate obtained in the solid-liquid separation step is brought into contact with carbon dioxide gas to produce lithium carbonate; a lithium carbonate recovery step of subjecting the liquid containing lithium carbonate obtained in the carbonation step to solid-liquid separation to obtain lithium carbonate as a solid; a lithium hydroxide production step of mixing the lithium carbonate obtained in the lithium carbonate recovery step with water and calcium hydroxide to produce lithium hydroxide and calcium carbonate, followed by solid-liquid separation to obtain a lithium hydroxide aqueous solution (1) as a liquid component; a recrystallization step of evaporating water from the lithium hydroxide aqueous solution (1) to crystallize lithium hydroxide; A method for producing lithium hydroxide, comprising:

3. 3. The method for producing lithium hydroxide according to claim 1, wherein the lithium-containing water has a lithium ion content of 18,000 ppm or less and a chloride ion content of 25,000 ppm or less.

4. 3. The method for producing lithium hydroxide according to claim 1 or 2, wherein the lithium-containing water is an ammonium ion-removed solution obtained by removing at least a portion of ammonium ions from metal- and other-containing water containing 3,000 ppm or more of lithium ions, 3,500 ppm or more of chloride ions, 20 ppm or more of sodium ions, each of which has a content of magnesium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions, and zinc ions of 10 ppm or less, and a content of calcium ions of 150 ppm or less, and which contains 3,000 ppm or more of ammonium ions.

5. The metal-containing water a step A of adding a calcium compound to acidic water to be treated that contains lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and chloride ions, and adjusting the pH of the water to be treated to 7.1 to 9.0 to form solid matter, and then subjecting the water to solid-liquid separation to obtain a treated liquid A; a step B of adding an alkaline substance to the treatment liquid A to adjust the pH of the treatment liquid A to 9.8 to 13.0 to form a solid, and then subjecting the treatment liquid A containing the solid to a solid-liquid separation treatment to obtain a treatment liquid B; a step C of adding at least one selected from the group consisting of ammonium carbonate, ammonium bicarbonate, and ammonium oxalate to the treatment liquid B to form a solid, and then subjecting the treatment liquid B containing the solid to solid-liquid separation to obtain a treatment liquid C; and step D of subjecting the treated solution C to bipolar electrodialysis, In the bipolar electrodialysis, the treatment liquid C is electrodialyzed using an electrodialysis device equipped with a bipolar membrane having an anion exchange layer and a cation exchange layer, and a cation exchange membrane, to obtain an alkaline liquid containing lithium ions, sodium ions, and ammonium ions that have permeated the cation exchange membrane. The method for producing lithium hydroxide according to claim 4.

6. 6. The method for producing lithium hydroxide according to claim 5, further comprising a step C' of filtering the treated liquid C through a nanofilter and subjecting the obtained filtrate to a reverse osmosis membrane treatment to obtain a concentrated liquid, and the obtained concentrated liquid is subjected to the step D.

7. 7. The method for producing lithium hydroxide according to claim 6, wherein the water to be treated is a leachate obtained by leaching with hydrochloric acid granules obtained by subjecting waste containing lithium ion batteries to a granulation process including a roasting step, a crushing step, and a magnetic separation step.

8. The lithium hydroxide obtained in the solid-liquid separation step contains lithium carbonate, a carbonate content conversion step of mixing the lithium hydroxide containing lithium carbonate with water, subjecting the resulting mixture to solid-liquid separation to obtain a lithium hydroxide aqueous solution (2) as a filtrate and lithium carbonate as a solid component, mixing the lithium carbonate with water and calcium hydroxide to produce lithium hydroxide and calcium carbonate, and subsequently subjecting the resulting mixture to solid-liquid separation to obtain a lithium hydroxide aqueous solution (3) as a liquid component; 3. The method for producing lithium hydroxide according to claim 1 or 2, further comprising carrying out a second recrystallization step of crystallizing lithium hydroxide by evaporating water from the lithium hydroxide aqueous solution (2) and the lithium hydroxide aqueous solution (3) obtained in the carbonate content conversion step.

9. In the carbonate content conversion step, lithium hydroxide containing lithium carbonate and water are mixed with the lithium hydroxide aqueous solution (1) obtained in the lithium hydroxide production step, The second recrystallization step also serves as the recrystallization step. The method for producing lithium hydroxide according to claim 8.

10. the concentrated liquid in which lithium hydroxide crystals have been produced, obtained in the second recrystallization step, is subjected to solid-liquid separation to obtain purified lithium hydroxide as a solid component and a purified lithium hydroxide filtrate as a liquid component; 9. The method for producing lithium hydroxide according to claim 8, wherein at least one of the following is carried out: The purified lithium hydroxide filtrate is recycled to the crystallization step. The purified lithium hydroxide filtrate is recycled to step D.

11. The method for producing lithium hydroxide according to claim 10, wherein the purified lithium hydroxide is washed with water and at least one of the following is carried out: The water used in the washing step is recycled to the crystallization step. The water used in the washing is circulated to the step D.

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