Method for producing raw material liquid for lithium compound, lithium-containing water, method for producing lithium hydroxide powder, and method for producing lithium carbonate powder

Abstract

To provide a method for yielding a lithium-containing liquid suitable as a raw material for producing lithium compounds of high purity, from to-be-treated water containing lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and anions serving as conjugate bases of acids, and to provide related techniques thereof.SOLUTION: Provided is a method for producing a raw material liquid for a lithium compound, comprising: step 1 of adding a sulfiding agent and a calcium compound to the to-be-treated water, subjecting the to-be-treated water containing the formed solid matter to solid-liquid separation to obtain a treated liquid A; step 2 of adding an oxalate ion source to the treated liquid A, subjecting the treated liquid A containing the formed solid matter to solid-liquid separation to obtain a treated liquid B; and step 3 of subjecting the treated liquid B to bipolar electrodialysis to obtain an alkaline liquid containing lithium ions and sodium ions as a raw material liquid for producing a lithium compound.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a raw material liquid for producing a lithium compound, lithium-containing water suitable as a raw material liquid for producing a lithium compound, a method for producing lithium hydroxide powder, and a method for producing lithium carbonate powder. [Background technology]

[0002] In recent years, recovery of 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 has been widely studied.

[0003] In the lithium ion battery, the materials typically used include lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, and lithium manganate for the anode, aluminum foil or copper foil for the electrode current collector, lithium hexafluorophosphate for the electrolyte, and aluminum or iron for the battery outer can. The material for the wiring of the substrate is typically copper. Therefore, examples of valuable metals that can be recovered from waste 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 a high yield and low cost.

[0004] Valuable metals recovered are highly valuable if they are obtained as high-purity substances. In order to obtain high-purity substances, a combination of various methods is required for separation. Generally speaking, recovery methods include dry processing, in which waste is put into a furnace and completely melted at high temperatures to separate the valuable metals and 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 valuable metals individually by using appropriate chemicals and setting appropriate 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 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. Patent Document 3 describes a method in which lithium-ion battery scrap is heated, melted, and reduced to obtain an alloy containing copper, nickel, and cobalt, and the alloy is brought into contact with sulfuric acid in the presence of a sulfurizing agent such as sulfur, to obtain a copper-containing solid and a leachate containing nickel and cobalt.

[0006] Patent Document 4 describes a method for acid leaching and further processing a black lump supply material containing material liberated from 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 leaching solution as precipitates, and lithium is reacted with sodium carbonate to produce lithium carbonate.

[0007] Patent Document 5 describes that in the process of producing lithium hydroxide monohydrate using lithium-containing brine as a raw material, a treatment with oxalic acid is carried out to reduce calcium in the brine. Patent Document 6 also describes the use of ammonium sulfide, calcium sulfide, potassium sulfide or sodium sulfide to form precipitates of cobalt and nickel sulfides in a method for producing a nitric acid product by precipitating and removing various metals from manganese-containing raw materials such as lithium-manganese batteries. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2023-63319 A [Patent Document 2] JP 2012-171827 A [Patent Document 3] JP 2019-77912 A [Patent Document 4] Special Publication No. 2023-516663 [Patent Document 5] Special Publication No. 2011-518257 [Patent Document 6] Special Publication No. 2015-531824 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 and circuit boards contains lithium ions, fluoride ions, anions (conjugate bases) derived from the acid used for leaching, etc. It also contains trace amounts of sodium ions.

[0010] Lithium is used in the manufacture 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, high purity is required for battery-grade lithium compounds, and it is necessary to sufficiently remove components other than lithium to recover lithium.

[0011] Regarding the recovery of lithium, the above-mentioned Patent Document 1 focuses on cobalt, nickel, and manganese. Regarding the recovery of lithium, it is described that lithium ion battery waste is subjected to processing such as crushing, and the resulting granular material is brought into contact with water to dissolve lithium, and then acid leaching is performed. However, the amount of lithium dissolved by bringing the granular material into contact with water is small, and most of it is transferred to the acid leaching solution. In other words, Patent Document 1 does not substantially describe the recovery of lithium.

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

[0013] Patent Document 3 focuses on copper, nickel, and cobalt, and does not specifically mention lithium recovery. Patent Document 4 describes converting lithium to lithium carbonate, but does not describe how to remove fluoride ions when the lithium contains them. Patent Documents 5 and 6 do not specifically mention lithium recovery.

[0014] In view of the above, an object of the present invention is to provide a method for obtaining a lithium-containing liquid useful as a raw material for producing a high-purity lithium compound from treated water containing lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and anions that are the conjugate base of an acid, and to provide related techniques thereof. [Means for solving the problem]

[0015] That is, the present invention is as follows. [1] A method for producing a raw material liquid for producing a lithium compound by treating acidic treatment water containing 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, comprising: In the treatment of the water to be treated, A step 1 of forming solid matter by adding a sulfurizing agent and a calcium compound to the water to be treated and making the pH of the water to be treated neutral or weakly alkaline, and then subjecting the water to solid-liquid separation to obtain a treated liquid A; a step 2 of adding an oxalate ion source to the treatment liquid A to form a solid matter, and then subjecting the treatment liquid A containing the solid matter to a solid-liquid separation process to obtain a treatment liquid B; a step 3 of electrodialyzing the treated liquid 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 liquid containing lithium ions and sodium ions that have permeated the cation exchange membrane as a raw material liquid for producing the lithium compound; The method for producing a raw material solution for producing a lithium compound comprises carrying out the steps of:

[0016] [2] The method for producing a raw material solution for producing a lithium compound according to [1], wherein the water to be treated in step 1 further contains phosphate ions, and the metal ions include at least one selected from the group consisting of magnesium ions, calcium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions and zinc ions.

[0017] [3] A method for producing a raw material solution for producing a lithium compound according to [2], wherein the water to be treated in step 1 has a lithium ion content of 1000 ppm or more, a sodium ion content of 50 ppm or less, a fluoride ion content of 1000 ppm or more, a strong acid ion content of 20000 ppm or more, a phosphate ion content of 500 ppm or more, an iron ion content of 5 ppm or more, a nickel ion content of 1000 ppm or more, and an aluminum ion content of 1500 ppm or more.

[0018] [4] The method for producing a raw material solution for producing a lithium compound according to any one of [1] to [3], wherein the sulfiding agent is at least one selected from the group consisting of ammonium sulfide, hydrogen sulfide, sodium sulfide, and sodium hydrogen sulfide.

[0019] [5] The method for producing a raw material solution for producing a lithium compound according to any one of [1] to [4], wherein the calcium compound is slaked lime.

[0020] [6] The method for producing a raw material solution for producing a lithium compound according to any one of [1] to [5], wherein in the step 1, the pH of the water to be treated is adjusted to 8 to 11.

[0021] [7] The method for producing a raw material solution for producing a lithium compound according to any one of [1] to [6], further comprising carrying out a step 4 in which the sulfiding agent is ammonium sulfide, the alkaline solution obtained in the step 3 further contains ammonia, and the ammonia is evaporated from the alkaline solution to obtain, as the raw material solution for producing the lithium compound, the alkaline solution from which at least a portion of the ammonia has been removed.

[0022] [8] The method for producing a raw material solution for producing a lithium compound according to [7], further comprising a step 5 of evaporating and concentrating the alkaline liquid that has been subjected to the step 4 to obtain a concentrated solution in which lithium ions are concentrated as the raw material solution for producing the lithium compound.

[0023] [9] The method for producing a raw material solution for producing a lithium compound according to any one of [1] to [8], wherein the water to be treated is a leachate obtained by leaching granules obtained by subjecting waste containing lithium ion batteries to a granulation process including a roasting step and a crushing step, with at least one strong acid selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid.

[0024]

[10] The method for producing a raw material solution for producing a lithium compound according to any one of [1] to [9], wherein the raw material solution for producing a lithium compound has a lithium ion content of 8000 ppm or more and a sodium ion content of 2500 ppm or less.

[0025]

[11] The method for producing a raw material solution for producing a lithium compound according to any one of [1] to

[10] , wherein the raw material solution for producing a lithium compound has a fluoride ion content of 300 ppm or less, a strong acid ion content of 5000 ppm or less, a phosphate ion content of 100 ppm or less, an iron ion content of 100 ppm or less, a nickel ion content of 100 ppm or less, an aluminum ion content of 100 ppm or less, and an ammonia content of 400 ppm or less.

[0026]

[12] Lithium-containing water having a lithium ion content of 8000 ppm or more, a sodium ion content of 300 to 2500 ppm, a fluoride ion content of 300 ppm or less, a total content of sulfate ions, chloride ions, and nitrate ions of 5000 ppm or less, a phosphate ion content of 100 ppm or less, an iron ion content of 100 ppm or less, a nickel ion content of 100 ppm or less, an aluminum ion content of 100 ppm or less, and an ammonia content of 400 ppm or less.

[0027]

[13] The lithium-containing water according to

[12] , which is used as a raw material liquid for producing a lithium compound.

[0028]

[14] A method for producing a lithium hydroxide powder, comprising crystallizing lithium hydroxide from a production raw material solution of a lithium compound having a pH of 10 or more produced by the production method according to any one of [1] to

[11] or from lithium-containing water having a pH of 10 or more according to

[13] .

[0029]

[15] The method for producing a lithium hydroxide powder according to

[14] , wherein the lithium-containing water containing the crystallized lithium hydroxide is subjected to solid-liquid separation and drying to obtain a lithium hydroxide powder.

[0030]

[16] A method for producing lithium carbonate powder, comprising contacting a raw material solution for producing a lithium compound produced by the production method according to any one of [1] to

[11] or the lithium-containing water according to

[13] with carbonic acid.

[0031]

[17] The method for producing lithium carbonate powder according to

[16] , comprising contacting the production raw material liquid of the lithium compound with carbonic acid in water to produce solid lithium carbonate, followed by performing solid-liquid separation treatment and drying to obtain lithium carbonate powder. Effect of the Invention

[0032] According to the present invention, there are provided a method for obtaining a lithium-containing solution useful as a raw material for producing a high-purity lithium compound from the treated water and related technologies.

Brief Description of the Drawings

[0033] [Figure 1] FIG. 1 is a diagram showing a bipolar electrodialysis apparatus used in the two-chamber method and an overview of electrodialysis. [Diagram 2] FIG. 2 is a diagram showing a bipolar electrodialysis apparatus used in the three-chamber method and an overview of electrodialysis.

Embodiments for Carrying Out the Invention

[0034] 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).

[0035] [Method for Producing a Raw Material Solution for Lithium Compound] The method for producing a raw material solution for a lithium compound of the present invention treats treated water containing lithium ions, sodium ions, metal ions other than lithium ions and sodium ions (hereinafter also referred to as "other metal ions"), fluoride ions, and at least one strong acid ion selected from sulfate ions, chloride ions, and nitrate ions by a predetermined process. Hereinafter, each of these components will be described.

[0036] <<Generation of Treated Water>> Lithium-ion batteries are widely used in electronic devices such as mobile phones and personal computers, and vehicles. They are discarded due to reasons such as the lifespan of battery products, manufacturing defects, or other reasons, generating lithium-ion battery waste.

[0037] The waste is subjected to a roasting process in which the waste is heated at a temperature of, for example, 500 to 1000°C, so that valuable metals in the batteries, such as lithium and cobalt, are converted into a form that is easily dissolved by acid. Then, a crushing process is performed using, for example, an impact crusher (sample mill, hammer mill, tornado mill, hammer crusher, etc.), to break the casing of the lithium-ion battery waste and granulate the waste. The obtained powder is sieved to obtain granular material from which aluminum has been removed to a certain extent under the sieve.

[0038] The granules are leached with a strong acid such as sulfuric acid, hydrochloric acid, or nitric acid to dissolve the various metals contained in the granules, and then solid-liquid separation is performed with the negative electrode active material (graphite) etc. The acid leaching solution obtained through such treatment is a typical treated water that is the target of the method for producing a raw material solution for producing a lithium compound of the present invention.

[0039] <<Treatment Water>> As explained above, the water to be treated is typically obtained by acid leaching, and therefore contains strong acid ions and is usually acidic. It also contains various metal ions dissolved by the strong acid. These components are explained below. In this specification, the water to be treated and other liquids may contain trace amounts of metals in elemental form. In the present invention, the content of metal ions in such various liquids includes the amount of the metals in elemental form.

[0040] <Lithium ion> The water to be treated contains lithium ions. The content is not particularly limited, but as described above, the water to be treated is typically an acid leachate of lithium ion battery waste, and contains a certain amount of lithium ions. Specifically, the content is, for example, 1000 ppm or more. A higher content is preferable because it increases the amount of lithium recovered per cycle, and the content is preferably 1500 ppm or more, more preferably 2500 ppm or more. The upper limit of the content is not particularly limited, but is, for example, 15000 ppm.

[0041] <Sodium ion> The water to be treated 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 content of sodium ions in the water to be treated is usually 50 ppm or less. From the viewpoint of obtaining lithium compounds with higher purity, the content is preferably 40 ppm or less, and more preferably 30 ppm or less. The content is usually 1 ppm or more.

[0042] It is difficult to selectively remove sodium ions from the water to be treated, particularly to separate them from lithium ions. As described above, the amount of sodium ions in the water to be treated is usually very small, so by adjusting the chemicals used in each step so as not to increase the amount of sodium ions as much as possible, it is possible to obtain treated water that is useful as a raw material for producing high-purity lithium compounds. Specifically, the mass ratio of lithium ions to sodium ions in the treated water may be adjusted to be within the range described below.

[0043] <Other metal ions> The water to be treated contains various metal ions other than lithium ions and sodium ions (hereinafter also referred to as "other metal ions") due to components of the lithium ion battery, such as the electrodes, electrolyte, and case.

[0044] Note that different battery manufacturers use different raw materials for the various components of lithium-ion batteries. In addition, the composition of treated water can vary depending on the method used to generate treated water from lithium-ion battery waste and on the operational variability of the process leading up to generation. For this reason, some treated water may contain a certain metal A at the level of several thousand ppm, while other treated water may not contain any metal A.

[0045] The water to be treated according to the present invention typically contains at least one other metal ion selected from the group consisting of magnesium ions, calcium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions and zinc ions. Of these, iron ions, aluminum ions and nickel ions are often contained.

[0046] 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 water to be treated is, for example, 6000 ppm or more (usually 100000 ppm or less). The total content may be 11000 to 63000 ppm.

[0047] When the water to be treated contains these metal ions, the content of each ion is as follows. The magnesium ion content in the water to be treated is, for example, 5 ppm or more (usually 150 ppm or less), and may be 15 to 100 ppm. The calcium ion content in the water to be treated is, for example, 30 ppm or more (usually 1500 ppm or less), and may be 80 to 800 ppm. The aluminum ion content in the water to be treated is, for example, 1500 ppm or more (usually 20000 ppm or less), and may be 2000 to 15000 ppm. The content of cobalt ions in the water to be treated is, for example, 500 ppm or more (usually 10,000 ppm or less), and may be 1,000 to 8,000 ppm. The nickel ion content in the water to be treated is, for example, 1000 ppm or more (usually 15000 ppm or less), and may be 2000 to 12000 ppm. The manganese ion content in the water to be treated is, for example, 2000 ppm or more (usually 25000 ppm or less), and may be 4000 to 15000 ppm. The iron ion content is, for example, 5 ppm or more (usually 2000 ppm or less), and may be 15 to 1000 ppm. The copper ion content in the water to be treated is, for example, 1500 ppm or more (usually 15000 ppm or less), and may be 2000 to 10000 ppm. The zinc ion content in the water to be treated is, for example, 15 ppm or more (usually 1200 ppm or less), and may be 30 to 600 ppm.

[0048] <Fluoride ion> Since fluorine-containing materials are widely used in the electrolyte and binder of lithium ion batteries, the water to be treated contains fluoride ions. The content of fluoride ions in the water to be treated is, for example, 1000 ppm or more. Although there is no particular upper limit, the content is usually 10000 ppm or less. The content of fluoride ions may be 1500 to 6000 ppm.

[0049] <Strong acid ion> The leaching of granulated lithium-ion battery waste is performed with strong acids capable of dissolving a wide variety of metals, specifically sulfuric acid, hydrochloric acid, and nitric acid. The treated water contains a large amount of anions derived from these strong acids. Hereinafter, sulfate ions, chloride ions, and nitrate ions are collectively referred to as strong acid ions.

[0050] Specifically, the content of strong acid ions in the water to be treated is, for example, 20000 ppm or more. Although there is no particular upper limit to the content, the content is usually 250000 ppm or less. The content of strong acid ions may be 30000 to 180000 ppm.

[0051] <Other ingredients> The water to be treated may contain other components. An example of such a component is phosphate ion, which is typically contained in the positive electrode material. The content of phosphate ion in the water to be treated is, for example, 500 ppm or more. Although there is no particular upper limit to the content, the content is usually 10000 ppm or less. The content of phosphate ion may be 1000 to 5000 ppm.

[0052] <ph> The water to be treated is typically a leachate obtained by leaching granulated lithium ion battery waste with a strong acid such as sulfuric acid, and therefore the liquid is usually acidic. Specifically, the pH of the water to be treated is, for example, 2.5 or less (usually 0.5 or more). The pH may be 0.8 to 2.0.

[0053] <<Each step in the manufacturing process of the raw material solution for lithium compounds>> Next, various steps carried out in the method for producing a raw material solution for producing a lithium compound of the present invention (hereinafter also simply referred to as the production method of the present invention) will be described. In the present invention, steps 1 to 3 described below are carried out as essential steps, and steps α, β, 4 and 5 may be carried out as optional steps.

[0054] In step 1, various metal ions and fluoride ions other than lithium ions and sodium ions in the water to be treated are precipitated and removed. In step 2, calcium ions, including those added in step 1, are removed. In step 3, cations (lithium ions, sodium ions, etc.) in the water to be treated are separated from anions and uncharged substances to recover water containing lithium ions. Step α may be performed for the purpose of reducing the process load of step 3 when the treated liquid B obtained in step 2 contains ammonia (ammonium ions). Step 4 is performed when a chemical that generates ammonia (ammonium ions) is used in step 1. Step β is a repetition of step 3, and can be performed immediately after step 3 or after step 4. Step 5 is performed when it is desired to increase the lithium content in the treated liquid obtained in step 3 or 4. Details of each of these steps will be described below.

[0055] <Process 1> In step 1, a sulfurizing agent and a calcium compound are added to the water to be treated, and the pH of the water to be treated is made neutral or weakly alkaline. In this liquid, the sulfurizing agent can precipitate a wide variety of metal ions (other metal ions) other than lithium ions and sodium ions as solids. The calcium compound also reacts with fluoride ions to form solid precipitates. If the lithium ion content in the water to be treated exceeds 2000 ppm, precipitation may occur in each step of the present invention, or the amount captured by the separation means (filter paper, etc.) during solid-liquid separation may increase. Therefore, water may be added to the water to be treated to dilute the lithium ion content to 2000 ppm or less before carrying out step 1.

[0056] The sulfurizing agent used in step 1 is not particularly limited, but specific examples thereof include ammonium sulfide, hydrogen sulfide, sodium sulfide, and sodium hydrogen sulfide. When a sulfurizing agent containing sodium is used, it is difficult to selectively remove sodium, so it is preferable to keep the mass ratio of lithium ions and sodium ions in the raw material liquid for production of a lithium compound obtained by the production method of the present invention (hereinafter, also simply referred to as the raw material liquid for production of the present invention) within the range described below by using a sulfurizing agent that does not contain sodium in combination, etc.

[0057] The amount of sulfurizing agent used is basically an equivalent amount or more in order to complete the precipitation reaction of other metal ions, and it is preferable to add the sulfurizing agent with an end point of -300 to -150 mV in terms of the ORP (oxidation-reduction potential) value of the water to be treated.

[0058] As mentioned above, in step 1, calcium compounds are added to the water to be treated to precipitate and remove fluoride ions. Since fluoride ions cannot be sufficiently removed in step 3, it is important to remove them in this step. Note that calcium ions derived from calcium compounds also react with phosphate ions and strong acid ions in the water to be treated (as a result, the amounts of these ions are also reduced).

[0059] The type of calcium compound is not particularly limited, but slaked lime (calcium hydroxide) is preferred. Fluoride ions can be captured by ion exchange resins, but other negative ions are released as counterions, and their removal can be problematic. In practical operation, regeneration of the resin is also necessary. Calcium compounds, especially slaked lime, are useful because when they react with fluoride ions to produce solids, they do not produce negative ions that require further removal.

[0060] Regarding the amount of calcium compound used, an excess amount is used in order to fully remove fluoride ions, keeping in mind that calcium compounds also react with phosphate ions, strong acid ions, etc. When the calcium compound is slaked lime, the pH of the water to be treated is the indicator, and it is sufficient to add calcium compound so as to make the pH neutral or slightly alkaline.

[0061] In step 1, the pH is adjusted to neutral or weakly alkaline. In this liquid pH, the sulfiding agent easily forms precipitates with other metal ions. When an alkaline compound such as ammonium sulfide or hydrated lime is used as the sulfiding agent and calcium compound, the pH can be adjusted to the above-mentioned range by adding the compound to the water to be treated without using a pH adjuster. Note that neutral or weakly alkaline is preferably a pH of 8 to 11, and more preferably 8.3 to 10 from the viewpoint of easily precipitating other metal ions.

[0062] By carrying out the above-described operations, precipitates derived from other metal ions and anions contained in the water to be treated are generated. These are then subjected to solid-liquid separation treatment. The means for this treatment are not particularly limited, and examples include filtration and filter press.

[0063] By carrying out the above-described step 1, a treated liquid A separated by solid-liquid separation is obtained. The composition of treated liquid A is, for example, as follows. The lithium ion content in the treatment liquid A is, for example, 1000 ppm or more (usually 15000 ppm or less). The lithium ion content may be 1200 to 8000 ppm. The sodium ion content in the treatment liquid A is, for example, 50 ppm or less. The sodium ion content is preferably 40 ppm or less, and more preferably 30 ppm or less. The sodium ion content is usually 1 ppm or more. The contents of iron ions, aluminum ions, nickel ions, copper ions, magnesium ions, cobalt ions, manganese ions and zinc ions in treatment solution A are, for example, 50 ppm or less, preferably 20 ppm or less, and more preferably 10 ppm or less. The calcium ion content in the treatment liquid A is, for example, 150 ppm or more (usually 2500 ppm or less). The calcium ion content may be 250 to 1500 ppm. The content of fluoride ions in the treatment liquid A is, for example, 100 ppm or less, preferably 80 ppm or less, and more preferably 40 ppm or less. The content of strong acid ions in the treatment liquid A (total of sulfate ions, hydrochloride ions, and nitrate ions) is, for example, 2000 ppm or more (usually 50000 ppm or less). The content of strong acid ions may be 4000 to 20000 ppm. The content of phosphate ions in treatment liquid A is, for example, 1000 ppm or less, preferably 500 ppm or less, and more preferably 100 ppm or less. When an agent that generates ammonia is used in step 1, the treatment liquid A contains ammonia. In this case, the content of ammonium ions in the treatment liquid A is, for example, 100 to 2000 ppm.

[0064] <Process 2> In the manufacturing method of the present invention, in step 2, an oxalate ion source is added to the treatment liquid A obtained in step 1. Calcium oxalate, which is formed by the reaction of oxalate ions with calcium ions, has low solubility and easily precipitates, so it can be easily removed by solid-liquid separation. In the oxalate ion source, counter cations other than protons remain in the liquid and can become impurities. For this reason, oxalic acid, whose counter cation is a proton, and ammonium oxalate, whose counter cation is an ammonium ion (which is alkaline and becomes volatile ammonia), are preferred.

[0065] By step 2, calcium (both that originally existed in the water to be treated and that added in step 1) can be removed by precipitation. The amount of the oxalate ion source used can be, for example, 2 to 10 molar times the amount of Ca in the treatment liquid A.

[0066] By adding the oxalate ion source, the liquid property of treatment liquid A, which became neutral or weakly alkaline in step 1, changes to the acidic side. If solid-liquid separation is not performed in step 1, the substance that precipitated in step 1 may re-dissolve due to the change in liquid property. To prevent this from happening, it is important to perform solid-liquid separation in step 1.

[0067] In step 2, calcium ions are precipitated by the addition of an oxalate ion source, and then solid-liquid separation is carried out to obtain treated liquid B. The specific means for the solid-liquid separation is the same as in the case of the solid-liquid separation in step 1.

[0068] By carrying out steps 1 and 2, almost all metal ions except for lithium ions and sodium ions in the treated water, i.e. other metal ions, are removed, and most anion components are also removed except for strong acid ions. As a result, lithium ions are dissolved in the water in the form of salts (ionized) with strong acid ions. Since lithium sulfate, lithium chloride, and lithium nitrate all have high solubility, the recovery loss of lithium ions up to step 2 is kept to a minimum.

[0069] The composition of the treatment liquid B obtained in step 2 is, for example, as follows. The lithium ion content in the treatment liquid B is, for example, 1000 ppm or more (usually 15000 ppm or less). The lithium ion content may be 1200 to 8000 ppm. The sodium ion content in the treatment liquid B is, for example, 50 ppm or less. The sodium ion content is preferably 40 ppm or less, and more preferably 30 ppm or less. The sodium ion content is usually 1 ppm or more. The contents of iron ions, aluminum ions, nickel ions, copper ions, calcium ions, magnesium ions, cobalt ions, manganese ions and zinc ions in treatment solution B are, for example, 50 ppm or less, preferably 20 ppm or less, and more preferably 10 ppm or less. The content of fluoride ions in treatment liquid B is, for example, 100 ppm or less, preferably 80 ppm or less, and more preferably 40 ppm or less. The content of strong acid ions in the treatment liquid B (total of sulfate ions, hydrochloride ions, and nitrate ions) is, for example, 2000 ppm or more (usually 50000 ppm or less). The content of strong acid ions may be 4000 to 20000 ppm. The content of phosphate ions in treatment liquid B is, for example, 1000 ppm or less, preferably 500 ppm or less, and more preferably 100 ppm or less. When an agent that generates ammonia is used in steps 1 and 2, treatment solution B contains ammonia. The content of ammonium ions in treatment solution B is, for example, 200 to 5000 ppm.

[0070] <Process α> In some cases, such as when a sulfiding agent that generates ammonia (ammonium ions) is used in step 1, the treated liquid B obtained in step 2 may contain ammonium ions. In this case, ammonia stripping similar to that in step 4 may be performed on treated liquid B as step α before carrying out step 3. By subjecting treated liquid B, in which the content of ammonium ions has been reduced in this way, to the next step 3 (bipolar electrodialysis), the electricity consumed for the movement of ammonium ions is reduced, which is desirable in terms of cost.

[0071] <Process 3> In step 3, the treated liquid B obtained in step 2 (or obtained by subsequently carrying out step α) is subjected to electrodialysis using a bipolar electrodialysis device. The details are as follows.

[0072] In bipolar electrodialysis, known bipolar electrodialysis devices can be used, and the so-called two-chamber method and three-chamber method can be adopted. In the two-chamber method, for example, a bipolar electrodialysis device 10 having a configuration shown in FIG. 1 is used.

[0073] 1, an anode 11 is disposed on the far left side, a left-end bipolar membrane 1 is disposed to the right of the anode 11, a left-side cation exchange membrane 22 is disposed to the right of the left-side cation exchange membrane 22, a central bipolar membrane 3 is disposed to the right of the central bipolar membrane 3, a right-side cation exchange membrane 24 is disposed to the right of the central bipolar membrane 3, a right-side bipolar membrane 5 is disposed to the right of the central bipolar membrane 3, and a cathode 12 is disposed on the far right side. Flow paths (1) to (4) are formed between these membranes.

[0074] The treated liquid B obtained in step 2 or step α is supplied to the flow paths (1) and (3) from the treated water tank 32. When the power supply for the bipolar electrodialysis device 10 is turned on, a current flows approximately perpendicular to the cation exchange membrane and the bipolar membrane, and only the cations in the treated liquid B pass through the cation exchange membrane and move toward the cathode 12 on the right side of FIG. 1. This separates the cations in the treated liquid B from substances with other charges. Focusing on the flow path (1), the anion exchange layer 3a of the central bipolar membrane 3 faces the left cation exchange membrane 22, and the cations that permeate the left cation exchange membrane 22 are condensed from the anion exchange layer 3a into OH. - is supplied to flow channel (2) to form hydroxide with the cations. The liquid flowing through flow channel (2) is then collected in alkaline liquid tank 34.

[0075] 1 shows an example in which the left-end bipolar membrane 1 is provided while arranging two sets of combinations of a central bipolar membrane 3 and a left anion exchange membrane 22. On the other hand, there is no limitation on the number of sets of the combinations, and for example, the left-end bipolar membrane 1 may be provided while the number of sets is set to 10 to 200.

[0076] In the three-chamber method, the bipolar electrodialysis device 10 is preferably equipped with an anion exchange membrane to separate anions more reliably. The bipolar electrodialysis device 10 in this case may have a configuration as shown in FIG.

[0077] 2, an anode 11 is disposed on the far left side, a left end bipolar membrane 1 is disposed to the right of it, a left anion exchange membrane 2 is disposed to the right of it, a left cation exchange membrane 2' is disposed to the right of it, a central bipolar membrane 3 is disposed to the right of it, a right anion exchange membrane 4 is disposed to the right of it, a right cation exchange membrane 4' is disposed to the right of it, a right end bipolar membrane 5 is disposed to the right of it, and a cathode 12 is disposed on the far right side. Flow paths (1) to (4') are formed between these membranes.

[0078] When the bipolar electrodialysis device 10 is powered on, the treated liquid B obtained in step 2 or step α is supplied from the treated water tank 6 to the flow paths (2) and (4). In the flow paths, anions (strong acid ions, etc.) in the treated liquid B move toward the anode 11. The behavior of cations and uncharged substances is the same as in the two-chamber method.

[0079] To repeat the explanation, the anion exchange layer 3a of the central bipolar membrane 3 and the left cation exchange membrane 2' face each other, and the cations that permeate the left cation exchange membrane 2' are oxidized from the anion exchange layer 3a to the OH. - is supplied to the flow channel (2') and forms hydroxide with the cations. The liquid (alkaline liquid) flowing through the flow channel (2') is then collected in the alkaline liquid tank 9.

[0080] In addition, when we look at the flow path (2), the anions permeate the left anion exchange membrane 2 and enter the flow path (1), where they are released from the left cation exchange layer 1b of the left bipolar membrane 1 as H + As a result, for example, a strong acid is regenerated and collected in the acid liquid tank 7.

[0081] 2 shows an example in which two 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. On the other hand, the number of such combinations (membrane structures in which the three types of membranes are repeatedly arranged) is not limited, and for example, the number of such combinations may be 10 to 200, and the right-end bipolar membrane 5 may be provided.

[0082] The conditions for the electrodialysis step are not limited. An example is as follows. Voltage of current applied in bipolar electrodialysis: 25~35V Current applied during bipolar electrodialysis: Maximum 4.4A Time for applying electric current: Change as appropriate depending on the desired lithium ion concentration in the alkaline solution and the amount of treatment solution B to be treated. Temperature at which bipolar electrodialysis is carried out (temperature of the treatment liquid): Taking into consideration the effects on various membranes such as the anion exchange membrane used in this embodiment, it can be set to room temperature, for example, 2 to 40°C.

[0083] In the alkaline solution obtained in step 3, impurities other than lithium ions and sodium ions (and ammonium ions) are well reduced (other metal ions are well reduced in step 2), and lithium ions and sodium ions are concentrated. Specifically, the composition of the alkaline solution is as follows:

[0084] The lithium ion content in the alkaline solution is, for example, 2000 ppm or more (usually 25000 ppm or less), and may be 3000 to 10000 ppm. The sodium ion content in the alkaline solution is, for example, 500 ppm or less. The sodium ion content is preferably 200 ppm or less, and more preferably 100 ppm or less. The sodium ion content is usually 10 ppm or more. The contents of iron ions, aluminum ions, nickel ions, copper ions, calcium ions, magnesium ions, cobalt ions, manganese ions and zinc ions in the alkaline liquid are, for example, 50 ppm or less, preferably 20 ppm or less, and more preferably 10 ppm or less. The content of fluoride ions in the alkaline solution is, for example, 100 ppm or less, preferably 80 ppm or less, and more preferably 40 ppm or less. In bipolar electrodialysis, fluoride ions seem to permeate the cation exchange membrane, and it is difficult to reduce the fluoride ions in step 3. The content of strong acid ions in the alkaline solution (total of sulfate ions, hydrochloride ions, and nitrate ions) is, for example, 2000 ppm or less (usually 100 ppm or less). The content of strong acid ions may be 200 to 1200 ppm. The content of phosphate ions in the alkaline solution is, for example, 1000 ppm or less, preferably 500 ppm or less, and more preferably 100 ppm or less. In cases where a chemical that generates ammonium ions is used in steps 1 and 2 (and step α is not performed), the alkaline solution contains ammonium ions. The content is, for example, 800 ppm or more (usually 12000 ppm or less). The content of ammonium ions may be 1500 to 8000 ppm.

[0085] The alkaline solution obtained in step 3, which mainly contains lithium ions and substantially does not contain ammonia, can be used to produce battery grade lithium carbonate or lithium hydroxide, as described below. That is, the alkaline solution is useful as a raw material solution for producing lithium compounds. If the alkaline solution contains ammonium ions, they are removed in step 4, which will be described later.

[0086] In addition, when bipolar electrodialysis is a three-chamber method, the acid solution contains anions that have not been removed (partitioned) by the time of step 2, and these anions are typically strong acid ions. In theory, the acid solution should not contain lithium ions, but in reality, it contains trace amounts. If this acid solution is reused (circulated) as a strong acid for leaching granulated lithium-ion battery waste, costs can be reduced and the lithium ions that have entered the acid solution can also be recovered.

[0087] <Step 4> If chemicals that produce ammonium ions are used in steps 1 and 2, the alkaline solution obtained in step 3 will contain ammonium ions (ammonia), which will be removed in step 4 (ammonia stripping).

[0088] As a method for removing ammonium ions, a conventionally known method can be adopted. The alkaline substances in the alkaline solution are basically lithium hydroxide and ammonia. Since lithium hydroxide is a stronger alkali than ammonia (the aqueous solution is more alkaline), the pH of the alkaline solution is usually 12 to 14, and a high proportion of ammonia exists in the alkaline solution in a free form rather than in ions, so that it can be easily removed by volatilization simply by heating or reducing the pressure (there is no need to add any chemicals to the alkaline solution to remove ammonia).

[0089] By carrying out ammonia stripping in step 4, a treated liquid with a reduced ammonium ion content is obtained. In addition, when the ammonia is volatilized and removed, some of the water, which is the solvent, also evaporates, causing the other components to become concentrated.

[0090] Specifically, the composition of the stripping treatment liquid obtained in step 4 is as follows: The content of ammonium ions in the stripping treatment liquid is, for example, 200 ppm or less, preferably 100 ppm or less, and is usually 5 ppm or more. The lithium ion content in the stripping treatment solution is, for example, 3000 ppm or more (usually 30000 ppm or less), and may be 3500 to 12000 ppm. The sodium ion content in the stripping treatment solution is, for example, 700 ppm or less. The sodium ion content is preferably 350 ppm or less, and more preferably 150 ppm or less. The sodium ion content is usually 20 ppm or more. The contents of iron ions, aluminum ions, nickel ions, copper ions, calcium ions, magnesium ions, cobalt ions, manganese ions and zinc ions in the stripping treatment solution are, for example, 50 ppm or less, preferably 20 ppm or less, and more preferably 10 ppm or less. The fluoride ion content in the stripping treatment liquid is, for example, 140 ppm or less, preferably 100 ppm or less, and more preferably 70 ppm or less. The content of strong acid ions in the stripping treatment liquid (total of sulfate ions, hydrochloride ions, and nitrate ions) is, for example, 3000 ppm or less (usually 150 ppm or less). The content of strong acid ions may be 300 to 1800 ppm. The content of phosphate ions in the stripping treatment liquid is, for example, 1000 ppm or less, preferably 500 ppm or less, and more preferably 100 ppm or less.

[0091] The stripping treatment liquid obtained in step 4 and having the above-mentioned composition and containing mainly lithium ions is useful as a raw material liquid for producing lithium compounds.

[0092] <Process β> Step β is a bipolar electrodialysis similar to step 3. For example, step β can be performed when step 3 is performed once and the content of anions in the obtained alkaline solution is high. In order to reduce the amount of electricity consumed, it is desirable to perform step β after step 4 in which ammonia is removed.

[0093] <Process 5> The alkaline solution (stripping solution) that has been subjected to step 4 (or the subsequent step β) is useful as a raw material solution for the production of lithium compounds. If a solution with a higher lithium ion concentration is to be obtained, it may be evaporated and concentrated by a known method in step 5. The conditions are, for example, as follows. Evaporator internal pressure: 0.1 to 0.8 atm Heating temperature (temperature of heated alkaline solution): 60~95℃ Treatment time: can be adjusted as needed to achieve the desired lithium ion concentration

[0094] In the production method of the present invention, the Na content in the starting water to be treated is low, and Na is basically not added in steps 1 to 5, or even if a Na-containing chemical is used, the amount is kept to a trace amount, so that the Na content in the concentrated liquid obtained in step 5 is also low. Therefore, Na does not pose a problem in obtaining battery grade (high purity) lithium hydroxide or lithium carbonate powder, which will be described later.

[0095] Specifically, the composition of the concentrated solution containing concentrated lithium obtained in step 5 is as follows: The ammonia content in the concentrated liquid is, for example, 400 ppm or less, and preferably 200 ppm or less. The lithium ion content in the concentrated solution is, for example, 8000 ppm or more (usually 100000 ppm or less), and may be 15000 to 70000 ppm. The sodium ion content in the concentrated liquid is, for example, 2500 ppm or less. The sodium ion content is preferably 1500 ppm or less, and more preferably 900 ppm or less. The sodium ion content is usually 100 ppm or more, and may be 300 ppm or more. The contents of iron ions, aluminum ions, nickel ions, copper ions, calcium ions, magnesium ions, cobalt ions, manganese ions and zinc ions in the concentrated liquid are, for example, 100 ppm or less, preferably 30 ppm or less, and more preferably 15 ppm or less. The fluoride ion content in the concentrated liquid is, for example, 300 ppm or less, preferably 200 ppm or less, and more preferably 150 ppm or less. The content of strong acid ions in the concentrated solution (total of sulfate ions, hydrochloride ions, and nitrate ions) is, for example, 5000 ppm or less (usually 300 ppm or more). The content of strong acid ions may be 500 to 4000 ppm. The phosphate ion content in the concentrated solution is, for example, 1000 ppm or less, preferably 500 ppm or less, and more preferably 100 ppm or less.

[0096] The concentrated liquid obtained in step 5 and having the above-mentioned composition and mainly containing lithium ions is useful as a raw material liquid for producing a lithium compound.

[0097] [Lithium-containing water] By carrying out the above-described method for producing a raw material liquid for producing a lithium compound of the present invention, lithium-containing water containing lithium ions and sodium ions and low contents of other components (e.g., other metal ions, fluoride ions, sulfate ions, chloride ions, and nitrate ions) can be obtained. Specific compositions thereof include those described as the composition of the concentrated liquid obtained in step 5.

[0098] The ratio of the content of lithium ions to the content of sodium ions (lithium ions / sodium ions) in the lithium-containing water of the present invention is, for example, 40 or more. This ratio is usually 250 or less. The ratio of the content of lithium ions to the content of strong acid ions (lithium ions / strong acid ions) in the lithium-containing water of the present invention is, for example, 5 or more. This ratio is usually 30 or less.

[0099] The lithium-containing water of the present invention described above contains lithium ions at a high concentration, and other metal ions contained are at the level of sodium ions. Although lithium and sodium are homologous elements, there is a large difference in the solubility of their hydroxides and compounds with other anions. By utilizing this characteristic, a high purity lithium compound can be produced from the lithium-containing water of the present invention. In other words, the lithium-containing water of the present invention is useful as a raw material liquid for producing lithium compounds.

[0100] [Method of manufacturing lithium hydroxide powder] The raw material liquid obtained by the method for producing a raw material liquid for producing a lithium compound of the present invention and the lithium-containing water of the present invention contain lithium ions and have a small content of other impurities as described above. The anions contained in the raw material liquid and the like are strong acid ions and hydroxide ions supplied in step 3, with the latter being contained in a sufficiently large amount. For this reason, the pH of the raw material liquid and the like is usually 10 or more (usually 13 or less).

[0101] When the water in the raw material liquid is evaporated, the lithium ions can be crystallized as lithium hydroxide, which is a compound with hydroxide ions, which are counter anions. Although the raw material liquid 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 that crystallization can be easily performed under conditions where lithium hydroxide crystallizes but sodium hydroxide does not crystallize.

[0102] The crystallized lithium hydroxide may be subjected to solid-liquid separation and, if necessary, washed with water. If the lithium hydroxide is dried, separation from the sodium ions and strong acid ions present in the raw material liquid is completed, and lithium hydroxide powder suitable for battery grade is obtained. The lithium hydroxide powder obtained may be recrystallized. Lithium hydroxide powder of higher purity may be obtained.

[0103] The specific composition of the lithium hydroxide powder obtained in the present invention is as follows. The lithium content in the lithium hydroxide powder is, for example, 16 to 17% by mass. The sodium content in the lithium hydroxide powder is, for example, 150 ppm or less. The content of iron, aluminum, nickel, copper, calcium, magnesium, cobalt, manganese, zinc, phosphoric acid and ammonia in the lithium hydroxide powder is, for example, 80 ppm or less, and preferably 10 ppm or less. The fluorine content in the lithium hydroxide powder is, for example, 400 ppm or less. The content of strong acid ions in the lithium hydroxide powder (the total of sulfate ions, chloride ions and nitrate ions) is, for example, 1000 ppm or less, and preferably 400 ppm or less. The balance of the lithium hydroxide powder consists of oxygen, hydrogen and inevitable impurities.

[0104] [Method of manufacturing lithium carbonate powder] Lithium carbonate can be produced by contacting the raw material liquid obtained by the method for producing a raw material liquid for producing a lithium compound of the present invention or the lithium-containing water of the present invention with carbonic acid. At the same time, a small amount of sodium carbonate is also produced. From the viewpoint of reaction efficiency, the contact with carbonic acid is preferably carried out in a wet manner by blowing carbon dioxide gas into the raw material liquid or the lithium-containing water. At this time, pressure may be applied to prevent the carbon dioxide gas from volatilizing.

[0105] Regarding the production of lithium carbonate and sodium carbonate, the solubility of lithium carbonate is lower than that of sodium carbonate, so when carbonation is performed, only lithium carbonate precipitates as a solid in water.

[0106] This is subjected to solid-liquid separation, washed with water or the like as necessary, and then dried to obtain lithium carbonate powder suitable for battery grade, in which sodium and other impurities have been separated. The lithium carbonate powder obtained may be recrystallized. Further, lithium carbonate powder with higher purity may be obtained.

[0107] The specific composition of the lithium carbonate powder obtained in the present invention is as follows. The lithium content in the lithium carbonate powder is, for example, 18 to 19 mass %. The sodium content in the lithium carbonate powder is, for example, 50 ppm or less. The content of iron, aluminum, nickel, copper, calcium, magnesium, cobalt, manganese, zinc and phosphate in the lithium carbonate powder is, for example, 100 ppm or less, and preferably 50 ppm or less. The fluorine content in the lithium carbonate powder is, for example, 900 ppm or less. The content of strong acid ions in the lithium carbonate powder (the total of sulfate ions, chloride ions, and nitrate ions) is, for example, 4000 ppm or less. The ammonia content in the lithium carbonate powder is, for example, 4000 ppm or less. The balance of the lithium carbonate powder is composed of oxygen, carbon and inevitable impurities. EXAMPLES

[0108] 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 mean conventional examples.

[0109] In the following Examples and Comparative Examples, various measurements were carried out as follows. Metal ion content: Measured using a Hitachi High-Tech Science ICP emission spectrometer SPS-5100. pH: Measured at 25°C using a pH meter and electrode HORIBA D-73. Nitrate ion concentration: Measured using a Tosoh IC-8100EX ion chromatograph. 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. Electrical resistance: Equilibrated in 0.5 mol / L saline and measured at 25°C using an alternating current. ·ORP (oxidation-reduction potential): Measured at 25°C using a HORIBA D-73 electrode.

[0110] [Example 1] The sulfuric acid leachate of the lithium ion waste was diluted 2-fold with pure water to 10 L and used as the water to be treated. The composition of the diluted leachate is shown in Table 1 below (pH: 1.92, ORP: 351 mV).

[0111] <Process 1> 480 g of slaked lime was added to the obtained diluted solution and mixed at room temperature for 30 minutes (pH: 7.59, ORP: 83 mV). 49 g of ammonium sulfide (available S concentration 5 mass%) was added to this neutralized solution and mixed at room temperature for 30 minutes (pH: 8.4, ORP: -216 mV). Next, 0.05 L of diluted slaked lime solution was added and mixed (pH: 9.4, ORP: 26 mV). Through the reaction in step 1, the diluted solution became 11.5 L from 10 L.

[0112] The obtained neutralized liquid was filtered under reduced pressure. 12 L of filtrate was obtained, including the water used to wash the filtration residue (pH: 9.4, ORP: 51 mV). The composition of the filtrate (treated liquid A) is shown in Table 1 below.

[0113] <Process 2> 22 g of ammonium oxalate monohydrate was added to the filtrate and mixed for 30 minutes. Then, 23 g of ammonium oxalate monohydrate was further added (the amount of ammonium oxalate was 3 times the molar amount of Ca in the filtrate) and stirred at room temperature for 30 minutes. The liquid after the reaction had a pH of 9.2 and an ORP of 25 mV. It was then filtered under reduced pressure. The composition of the obtained filtrate (treated liquid B) is shown in Table 1 below.

[0114] [Table 1]

[0115] It can be seen that most metals except for lithium and sodium, as well as fluoride ions, were removed, and that sulfate ions were partially removed (probably by calcium hydroxide). The calcium added in step 1 was also successfully removed by ammonium oxalate (step 2).

[0116] <Process 3> The treated liquid B obtained in step 2 was subjected to electrodialysis using the bipolar electrodialysis device shown in Figure 2. The electrodialysis conditions were as follows. Electrodialysis equipment: Astom's bipolar membrane electrodialysis equipment, Asilizer BPED EX-3B Anion exchange membrane: Astom AHA (electrical resistance is 4.1Ωcm 2 ) Cation exchange membrane: Cation exchange membrane (Astrom CMB) Bipolar membrane: Astom BP1-EX *Ten anion exchange membranes and ten cation exchange membranes, and eleven bipolar membranes were used. The anion exchange membrane, cation exchange membrane, and bipolar membrane were repeated ten times (the cation exchange membrane and the anion exchange layer of the bipolar membrane faced each other). Voltage: 35V constant Current: Variable, with a maximum of 4.4A. When the upper limit of the current was reached, the voltage was lowered so as not to exceed the maximum value of the current.

[0117] - 12L of the above treatment solution B is added to the treated water tank at the initial stage. - 3L of pure water is added to the acid tank at the initial stage. - 3.5L of pure water is added to the alkaline solution tank at the initial setting. -Temperature of the liquid flowing through each tank and electrodialysis device during electrodialysis: 20~37℃ Treatment time: Electrodialysis treatment was performed for more than 16 hours (approximately 1 day).

[0118] The compositions of the desalted liquid (recovered in the tank for treated water), alkaline liquid, and acid liquid obtained by the above electrodialysis are shown in Table 2 below. [Table 2]

[0119] It can be seen that lithium (and sodium and ammonia) are concentrated in the alkaline solution, and various anions are removed or reduced. However, there was no reduction in the fluoride ion content, probably because it passed through the cation exchange membrane (it was sufficiently removed in step 1).

[0120] <Step 4> Ammonia stripping was carried out on the alkaline solution (pH>10) obtained in step 3. The alkaline solution was placed in a vacuum reaction vessel equipped with a stirrer, and heated to 50°C with a heater while stirring. The reaction vessel was connected to a vacuum pump, and the vacuum pressure was adjusted to 50 kPa to volatilize the ammonia. In step 4, the liquid volume before and after the operation was reduced from 3.5 L to 2.6 L.

[0121] The composition of the resulting stripping treatment solution is shown in Table 3 below. [Table 3]

[0122] It can be seen that lithium is concentrated and ammonium ions are removed or reduced in the stripping treatment solution. It can also be seen that sulfate ions still remain as anions, forming a mixed solution of lithium hydroxide and lithium sulfate.

[0123] <Process β> The stripping treatment liquid obtained in step 4 was subjected to bipolar electrodialysis treatment in the same manner as in step 3. 4 L of the stripping treatment liquid was initially supplied to the tank for treated water in the initial state, and 1 L and 4 L of pure water were initially supplied to the acid liquid tank and the alkaline liquid tank, respectively.

[0124] The compositions of the desalted solution, alkaline solution and acid solution after electrodialysis are shown in Table 4 below. [Table 4]

[0125] The second bipolar electrodialysis treatment (step β) reduced the sulfate ions in the alkaline solution.

[0126] <Process 5> The alkaline solution obtained in the second electrodialysis (step β) was used as the raw treatment solution and was subjected to evaporation and concentration under the following conditions. Evaporation and concentration device: Rotary evaporator N-1000 (EYELA, manufactured by Tokyo Rikakikai Co., Ltd.) Pressure inside the evaporator: 220hPa (approx. 0.2 atm) Filtrate temperature: 85℃ Operating time of the device: 6 hours (time required to concentrate 2.3 L of original solution to 0.4 L)

[0127] The composition of the solution before and after concentration is shown in Table 5. A concentrated solution (pH>12) containing high concentrations of lithium was obtained. [Table 5]

[0128] <Production of lithium hydroxide powder> Using the concentrate obtained in step 5 as the raw material, the water was further evaporated until the concentrate of 0.2 L was concentrated to 0.03 L, and the concentrate was filtered through filter paper No. 5C to obtain a solid matter. The obtained solid matter was washed with a 10% by mass water / 90% by mass ethanol solution and then dried at 70° C. for 6 hours to obtain a lithium hydroxide powder.

[0129] The composition of the resulting lithium hydroxide powder is shown in Table 6 below. The lithium hydroxide powder in Table 6 contains some impurities, so it was recrystallized again to produce a purified lithium hydroxide powder. Specifically, a part of the lithium hydroxide powder was redissolved in pure water to prepare a solution with a Li ion concentration of about 1000 ppm, and the water was evaporated until 0.2 L of this solution was concentrated to 0.03 L, and the solution was filtered with 5C filter paper to obtain a solid. The obtained solid was washed with a 10 mass % water / 90 mass % ethanol solution and then dried at 70 ° C for 6 hours to obtain a purified lithium hydroxide powder. The composition of the obtained purified lithium hydroxide powder is shown in Table 6.

[0130] [Table 6]

[0131] <Production of lithium carbonate powder> The concentrated liquid obtained in step 5 above was used as a raw material to produce lithium carbonate powder.

[0132] (Manufactured with sodium carbonate) The concentrated solution was diluted with pure water to obtain a 40 g / L lithium hydroxide aqueous solution. Sodium carbonate was added to the solution so that the ratio of carbonate ions to lithium was 2 molar times, and the mixture was stirred at room temperature for 10 minutes to obtain lithium carbonate. The obtained lithium carbonate-containing solution was filtered with 5C filter paper, washed with a mixture of 90% by mass ethanol and 10% by mass water, and then dried at 70°C for 6 hours to obtain lithium carbonate powder.

[0133] (Produced using carbon dioxide) Sodium carbonate and sulfuric acid were reacted in a Kip apparatus to generate carbon dioxide gas. The generated carbon dioxide gas was introduced into an aqueous solution of lithium hydroxide, and the aqueous solution was stirred at room temperature for 10 minutes to obtain lithium carbonate. After that, filtration, washing and drying were performed in the same manner as above (production using sodium carbonate), and lithium carbonate powder was obtained.

[0134] The compositions of the lithium carbonate powders obtained above (production using sodium carbonate) and (production using carbon dioxide) were analyzed. The results are shown in Table 7 below.

[0135] [Table 7]

[0136] It can be seen that in the production of lithium carbonate powder using sodium carbonate, sodium ions from the solution were trapped in the crystals, resulting in unacceptable levels of sodium remaining, whereas in the production using carbon dioxide, the amounts of sodium ions and other ions in the lithium carbonate powder were sufficiently low that they could meet the general standards for current battery grades.

[0137] [Comparative Example 1] The sulfuric acid leachate of the lithium ion waste was diluted 2-fold with pure water to make 100 mL (pH: 0.95, ORP: 1081 mV). This diluted solution was used as the water to be treated. The composition of the diluted solution is shown in Table 8 below.

[0138] 1 g of 11% by mass NaSH aqueous solution was added to the obtained diluted solution and mixed at room temperature for 30 minutes (pH: 0.96, ORP: 307 mV). Then, 3.7 g of hydrated lime was added and mixed at room temperature for 30 minutes (pH: 3.73, ORP: 288 mV). Next, 23 g of a 28% by mass aqueous ammonia solution was added, and then 1.8 g of an 11% by mass aqueous NaSH solution was added again, followed by mixing at room temperature for 30 minutes (pH: 8.9, ORP: -53 mV).

[0139] The resulting neutralized liquid was filtered under reduced pressure, and the composition of the resulting filtrate is shown in Table 8 below. [Table 8]

[0140] Because a chemical containing sodium was used, the amount of Na in the post-treatment liquid (the filtrate obtained by filtering the neutralized liquid) was quite high. It is difficult to remove this. Even if treated water is obtained from this post-treatment liquid by removing metal ions other than lithium and sodium, considerable amounts of sodium hydroxide and sodium carbonate are produced when lithium is crystallized as lithium hydroxide or converted to lithium carbonate, making it difficult to obtain a high-purity (low sodium content) lithium compound powder. [Explanation of symbols]

[0141] 1 Left end bipolar membrane 1a Left anion exchange layer 1b Leftmost cation exchange layer 2. Left anion exchange membrane 2´ Left cation exchange membrane 3 Central bipolar membrane 3a Central anion exchange layer 3b Central cation exchange layer 4 Right side anion exchange membrane 4´ Right side cation exchange membrane 5 Right end bipolar membrane 5a Right anion exchange layer 5b Right end cation exchange layer 6. Treated water tank 7. Acid tank 9 Alkaline Liquid Tank 10. Bipolar electrodialysis device 11 Anode 12 Cathode 22 Left cation exchange membrane 24 Right cation exchange membrane 32 Untreated water tank 34 Alkaline Liquid Tank< / ph>

Claims

1. A method for producing a raw material liquid for producing a lithium compound by treating acidic treatment water containing 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, comprising: In the treatment of the water to be treated, A step 1 of adding a sulfurizing agent and a calcium compound to the water to be treated and making the pH of the water to be treated neutral or weakly alkaline to form solid matter, and then subjecting the water to solid-liquid separation to obtain a treated liquid A; a step 2 of adding an oxalate ion source to the treatment liquid A to form a solid matter, and then subjecting the treatment liquid A containing the solid matter to a solid-liquid separation process to obtain a treatment liquid B; a step 3 of electrodialyzing the treated liquid 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 liquid containing lithium ions and sodium ions that have permeated the cation exchange membrane as a raw material liquid for producing the lithium compound; The method for producing a raw material solution for producing a lithium compound comprises carrying out the steps of:

2. 2. The method for producing a raw material solution for producing a lithium compound according to claim 1, wherein the water to be treated in step 1 further contains phosphate ions, and the metal ions include at least one selected from the group consisting of magnesium ions, calcium ions, aluminum ions, cobalt ions, nickel ions, manganese ions, iron ions, copper ions and zinc ions.

3. 3. The method for producing a raw material solution for producing a lithium compound according to claim 2, wherein the water to be treated in step 1 has a lithium ion content of 1000 ppm or more, a sodium ion content of 50 ppm or less, a fluoride ion content of 1000 ppm or more, a strong acid ion content of 20000 ppm or more, a phosphate ion content of 500 ppm or more, an iron ion content of 5 ppm or more, a nickel ion content of 1000 ppm or more, and an aluminum ion content of 1500 ppm or more.

4. 4. The method for producing a raw material solution for producing a lithium compound according to claim 3, wherein the sulfiding agent is at least one selected from the group consisting of ammonium sulfide, hydrogen sulfide, sodium sulfide, and sodium hydrogen sulfide.

5. The method for producing a raw material solution for producing a lithium compound according to claim 3, wherein the calcium compound is slaked lime.

6. 4. The method for producing a raw material solution for producing a lithium compound according to claim 3, wherein in the step 1, the pH of the water to be treated is adjusted to 8 to 11.

7. the sulfiding agent is ammonium sulfide; The alkaline solution obtained in step 3 further contains ammonia, A step 4 is further carried out in which ammonia is evaporated from the alkaline solution to obtain an alkaline solution from which at least a portion of the ammonia has been removed as a raw material solution for producing the lithium compound. A method for producing the raw material solution for producing the lithium compound according to claim 3.

8. 8. The method for producing a raw material solution for producing a lithium compound according to claim 7, further comprising a step 5 of evaporating and concentrating the alkaline solution that has been subjected to the step 4 to obtain a concentrated solution in which lithium ions are concentrated as the raw material solution for producing the lithium compound.

9. The method for producing a raw material solution for producing a lithium compound according to any one of claims 1 to 8, wherein the water to be treated is a leachate obtained by leaching granules obtained by subjecting waste containing lithium ion batteries to a granulation process including a roasting step and a crushing step, with at least one strong acid selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid.

10. The method for producing a raw material solution for producing a lithium compound according to any one of claims 1 to 8, wherein the content of lithium ions in the raw material solution for producing a lithium compound is 8000 ppm or more and the content of sodium ions in the raw material solution for producing a lithium compound is 2500 ppm or less.

11. 11. The method for producing a raw material solution for producing a lithium compound according to claim 10, wherein the raw material solution for producing a lithium compound has a fluoride ion content of 300 ppm or less, a strong acid ion content of 5000 ppm or less, a phosphate ion content of 100 ppm or less, an iron ion content of 100 ppm or less, a nickel ion content of 100 ppm or less, an aluminum ion content of 100 ppm or less, and an ammonia content of 400 ppm or less.

12. Lithium-containing water having a lithium ion content of 8000 ppm or more, a sodium ion content of 300 to 2500 ppm, a fluoride ion content of 300 ppm or less, a total content of sulfate ions, chloride ions and nitrate ions of 5000 ppm or less, a phosphate ion content of 100 ppm or less, an iron ion content of 100 ppm or less, a nickel ion content of 100 ppm or less, an aluminum ion content of 100 ppm or less, and an ammonia content of 400 ppm or less.

13. The lithium-containing water according to claim 12, which is used as a raw material liquid for producing a lithium compound.

14. A method for producing lithium hydroxide powder, comprising crystallizing lithium hydroxide from a raw material solution for producing a lithium compound having a pH of 10 or more produced by the method for producing the lithium compound according to claim 1 or from lithium-containing water having a pH of 10 or more according to claim 13.

15. The method for producing a lithium hydroxide powder according to claim 14, wherein the lithium-containing water containing the crystallized lithium hydroxide is subjected to solid-liquid separation and drying to obtain a lithium hydroxide powder.

16. A method for producing lithium carbonate powder, comprising contacting a raw material liquid for producing a lithium compound produced by the method for producing according to claim 1 or the lithium-containing water according to claim 13 with carbonic acid.

17. The method for producing lithium carbonate powder according to claim 16, wherein the production raw material liquid of the lithium compound is contacted with carbonic acid in water to produce solid lithium carbonate, and then a solid-liquid separation treatment and drying are performed to obtain lithium carbonate powder.

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