Method for producing raw material solution for producing lithium compound, method for producing lithium hydroxide powder, and method for producing lithium carbonate powder

Abstract

To provide a process for obtaining a lithium-containing liquid useful as a raw material for producing a high-purity lithium compound by leaching a waste such as a lithium ion battery with an acid and treating the obtained leachate as water to be treated, in which the amount of substances to be a waste is suppressed.SOLUTION: In a method for producing a raw material liquid for producing a lithium compound, water to be treated is subjected to predetermined step 1, the obtained treatment liquid A is subjected to predetermined step 2, the obtained treatment liquid B is subjected to predetermined step 3, and the obtained treatment liquid C is subjected to predetermined step 4.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, a method for producing lithium hydroxide powder, and a method for producing lithium carbonate powder.

Background Art

[0002] In recent years, extensive studies have been conducted on recovering various valuable metals from waste such as lithium-ion batteries and substrates discarded due to reasons such as product lifespan and manufacturing defects.

[0003] In the lithium-ion battery, typical materials used include lithium cobaltate, lithium nickelate, lithium iron phosphate, and lithium manganate for the positive electrode, aluminum foil or copper foil for the current collector of the electrode, lithium hexafluorophosphate for the electrolyte, and aluminum or iron for the battery casing. Also, 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, iron, etc. Various studies have been made to recover these metals at high yields and low costs.

[0004] Valuable metals obtained as high-purity substances have high value. To obtain high-purity substances, separation is performed by combining various methods. Regarding the recovery method, generally speaking, there are a dry treatment in which waste is put into a furnace and melted at a high temperature to separate into valuable metal and slag, and a wet treatment using methods such as acids, neutralization, and solvent extraction. The wet treatment has the merit that it consumes less energy and can separate valuable metals individually by appropriately setting the chemicals and conditions used.

[0005] As an example of studying the wet treatment of waste, for example, Patent Document 1 focuses on cobalt, nickel, and manganese, and describes performing a specific pre-stage neutralization step and a post-stage neutralization step to obtain a neutralization residue containing these metals. Patent Document 2 describes that an aqueous solution containing sodium sulfate and lithium is treated with a bipolar electrodialysis device equipped with a cation exchange membrane, a bipolar membrane, and an anion exchange membrane to obtain an aqueous solution of lithium-containing sodium hydroxide, and that the aqueous solution can be used as a pH adjuster.

[0006] Patent Document 3 describes a method of acid-leaching and further treating a black mass feed material containing a material released from a lithium iron phosphate battery material, and adjusting the pH to 8 to 11 with calcium hydroxide and reacting lithium with sodium carbonate to form lithium carbonate in order to remove iron and phosphorus in the acid leachate as a precipitate.

[0007] Note that Patent Document 4 describes that in the process of producing lithium hydroxide monohydrate using a lithium-containing brine as a raw material, oxalic acid treatment is performed to reduce calcium in the brine.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] The leachate obtained by acid-leaching waste such as lithium-ion batteries contains lithium ions, fluoride ions, anions (conjugate bases) derived from the acid used for leaching, etc. It also contains a trace amount 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 above-mentioned 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 Patent Document 1 focuses on cobalt, nickel, and manganese. Regarding the recovery of lithium, it is described that granular materials obtained by subjecting waste of lithium-ion batteries to treatments such as crushing are brought into contact with water to dissolve lithium, and then acid leaching is carried out. However, the amount of lithium dissolved by bringing the granular materials into contact with water is small, and most of it migrates to the acid leachate. That is, Patent Document 1 has no substantial description regarding the recovery of lithium.

[0012] Patent Document 2 relates to a process using a bipolar electrodialysis device. Fluoride ions are mixed in the acid leachate derived from, for example, the electrolyte of a lithium-ion battery. From the study by the present inventor, it has been found that fluoride ions cannot be sufficiently separated from lithium in the above process.

[0013] Patent Document 3 describes converting lithium to lithium carbonate, but there is no description on how to remove it when lithium contains fluoride ions. Patent Document 4 does not particularly mention lithium recovery.

[0014] From the above, the present inventor has repeatedly studied for the purpose of providing a method for obtaining a lithium-containing solution 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 which are conjugate bases of acids.

[0015] As a result, the inventor has developed a method for producing a raw material solution for lithium compounds by treating acidic water to be treated 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. In the treatment of the water to be treated, 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 adjusted to neutral to weakly alkaline to form solids. Then, in Step 1, the water to be treated containing the solids is subjected to solid-liquid separation to obtain Treatment Liquid A. In Step 2, an oxalate ion source is added to Treatment Liquid A to form solids, and then the Treatment Liquid A containing the solids is subjected to solid-liquid separation to obtain Treatment Liquid B. In Step 3, Treatment Liquid B is subjected to electrodialysis using an electrodialysis apparatus equipped with a bipolar membrane having an anion exchange layer and a cation exchange layer and a cation exchange membrane, so as to obtain an alkaline solution containing lithium ions and sodium ions that have permeated through the cation exchange membrane as the raw material solution for lithium compound production. The inventor conceived of the invention of the method for producing a raw material solution for lithium compounds and filed a patent application (Japanese Patent Application No. 2023-188699).

[0016] However, it has been found that the present invention has the following problems. From the perspective of the chemical cost of the acid, sulfuric acid is typically selected as the first candidate for the acid for leaching. Therefore, the water to be treated in the above invention typically contains a large amount of sulfate ions as strong acid ions. When a calcium compound essential for fluoride removal is added to this water to be treated, a large amount of gypsum (mainly composed of calcium sulfate) is generated. This gypsum will be disposed of as industrial waste, but due to the large amount of gypsum, the waste treatment cost can be high.

[0017] Therefore, the present invention relates to a process for acid-leaching waste such as lithium-ion batteries, treating the obtained leachate (containing lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and anions that are conjugate bases of acids) as water to be treated to obtain a lithium-containing solution useful as a raw material for producing high-purity lithium compounds, and aims to provide a process in which the amount of substances that can become waste is suppressed compared to the invention according to the above prior application, as well as elemental technologies and related technologies that can be used in the process.

Means for Solving the Problems

[0018] The present inventor has intensively studied to solve the above problems. When hydrochloric acid is used for leaching, even if calcium chloride is formed by chloride ions as counter anions and calcium ions derived from calcium compounds, its solubility in water is relatively high. From this, the present inventor has found that by using hydrochloric acid for leaching and combining it with an appropriate subsequent process, the generation of substances that can become waste can be suppressed, and thus the present invention has been conceived.

[0019] That is, the present invention is as follows. [1] A method for producing a raw material solution for producing a lithium compound by treating acidic water to be treated containing lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and chloride ions, wherein in the treatment of the water to be treated, Step 1 of adding a calcium compound to the water to be treated and adjusting the pH of the water to be treated to weakly alkaline to form a solid, and then subjecting the water to be treated containing the solid to solid-liquid separation treatment to obtain treatment liquid A; Step 2 of adding an alkaline substance to treatment liquid A and adjusting the pH of treatment liquid A to alkaline to form a solid, and then subjecting treatment liquid A containing the solid to solid-liquid separation treatment to obtain treatment liquid B; Step 3 of adding an oxalate ion source and / or a carbonate ion source to treatment liquid B to form a solid, and then subjecting treatment liquid B containing the solid to solid-liquid separation treatment to obtain treatment liquid C; Step 4 of obtaining, as a raw material solution for producing the lithium compound, an alkaline solution containing lithium ions and sodium ions that have permeated through the cation exchange membrane by subjecting the treatment liquid C to electrodialysis using an electrodialysis apparatus equipped with a bipolar membrane having an anion exchange layer and a cation exchange layer and a cation exchange membrane A method for producing a raw material solution for producing a lithium compound, which comprises carrying out the above steps.

[0020] [2] The pH of the water to be treated supplied to the above Step 1 is 0.1 to 2.5, In the above Step 1, the pH of the water to be treated is adjusted to 7.1 to 9.0, In the above Step 2, the pH of the treatment liquid A is adjusted to 9.8 to 13.0. The method for producing a raw material solution for producing a lithium compound according to [1].

[0021] [3] Step 3' of filtering the treatment liquid C with a nanofilter and subjecting the obtained filtrate to reverse osmosis membrane treatment to obtain a concentrated liquid, and supplying the concentrated liquid obtained in Step 3' to the above Step 4. The method for producing a raw material solution for producing a lithium compound according to [1] or [2].

[0022] [4] The calcium compound and the alkaline substance are slaked lime, and the nanofilter is formed of poly(piperazine) or polyamide. The method for producing a raw material solution for producing a lithium compound according to [3].

[0023] [5] The water to be treated supplied to the above 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. The method for producing a raw material solution for producing a lithium compound according to any one of [1] to [4].

[0024] [6] The content of lithium ions in the water to be treated used in the above-mentioned step 1 is 1000 ppm or more, the content of sodium ions is 100 ppm or less, the content of fluoride ions is 1000 ppm or more, the content of chloride ions is 10000 ppm or more, the content of phosphate ions is 400 ppm or more, the content of iron ions is 5 ppm or more, the content of nickel ions is 300 ppm or more, and the content of aluminum ions is 1500 ppm or more. A method for producing a raw material liquid for producing a lithium compound according to any one of [1] to [5].

[0025] [7] The water to be treated is a leachate obtained by leaching a granular material obtained by subjecting waste containing a lithium-ion battery to a granulation treatment including a roasting step, a crushing step, and a magnetic separation step with hydrochloric acid. A method for producing a raw material liquid for producing a lithium compound according to any one of [1] to [6].

[0026] [8] The content of lithium ions in the alkaline liquid is 2000 ppm or more, and the content of sodium ions is 800 ppm or less. A method for producing a raw material liquid for producing a lithium compound according to any one of [1] to [7].

[0027] [9] Ammonium carbonate and / or ammonium bicarbonate is used in the above-mentioned step 3, the alkaline liquid obtained in the above-mentioned step 4 further contains ammonia, and step 5 of evaporating ammonia from the alkaline liquid to obtain an alkaline liquid from which at least a part of the ammonia has been removed as the raw material liquid for producing the lithium compound is further carried out. [1] to [8]. A method for producing a raw material liquid for producing a lithium compound according to any one of the above.

[0028]

[10] Waste containing a lithium-ion battery is heated at 500 to 1000 °C, and then crushed using a crusher to granulate the waste. Magnetic separation is performed on the obtained granulated material, and the obtained non-magnetically attached material is leached with hydrochloric acid to obtain a hydrochloric acid leaching solution. Using this leaching solution as the water to be treated, the method for producing a raw material solution for producing a lithium compound according to any one of [1] to [9] is implemented. A method for producing a raw material solution for producing a lithium compound.

[0029]

[11] A method for producing lithium hydroxide powder, wherein lithium hydroxide is crystallized from a raw material solution for producing a lithium compound having a pH of 10 or more, which is produced by the production method according to any one of [1] to

[10] .

[0030]

[12] A method for producing lithium hydroxide powder according to

[11] , wherein solid-liquid separation treatment and drying are performed on the lithium-containing water containing the crystallized lithium hydroxide to obtain lithium hydroxide powder.

[0031]

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

[10] is brought into contact with carbonic acid.

[0032]

[14] A method for producing lithium carbonate powder according to

[13] , wherein the contact between the raw material solution for producing the lithium compound and carbonic acid is carried out in water to generate solid lithium carbonate, and then solid-liquid separation treatment and drying are carried out to obtain lithium carbonate powder.

Advantages of the Invention

[0033] According to the present invention, regarding the above process, a process in which the amount of substances that can become waste is suppressed compared to the invention according to the above prior application, and elemental technologies that can be used in the process and their related technologies are provided.

Brief Description of the Drawings

[0034]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0035] 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).

[0036] [Method for Producing a Lithium Compound Production Raw Material Solution] From one perspective, the method for producing a lithium compound production raw material solution according to the present invention is a process that starts with waste containing a lithium-ion battery, leaches it with hydrochloric acid, and further processes the obtained hydrochloric acid leachate (water to be treated) in a predetermined process. This will be referred to as the method for producing a lithium compound production raw material solution of Invention 1 of the present invention.

[0037] From another perspective, the method for producing a lithium compound production raw material solution according to the present invention is a process that focuses on the water to be treated in the above-mentioned Invention 1 and processes it in a predetermined process starting from this. This will be referred to as the method for producing a lithium compound production raw material solution of Invention 2 of the present invention, and the methods for producing a lithium compound production raw material solution of Invention 1 and Invention 2 will be collectively referred to as the method for producing a lithium compound production raw material solution of the present invention (more simply, also referred to as "the production method of the present invention"). It should be noted that Invention 1 and Invention 2 are not strictly distinguished.

[0038] The method for producing a lithium compound production raw material solution of Invention 1 of the present invention is to subject waste containing a lithium-ion battery to a predetermined treatment to obtain water to be treated 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 chloride ions, and to process this water to be treated by a predetermined process. Hereinafter, each of these components will be described.

[0039] <<Generation of Water to be Treated>> Lithium-ion batteries are widely used in electronic devices such as mobile phones and personal computers, as well as in vehicles. Due to reasons such as the lifespan of battery products, manufacturing defects, or other reasons, these electronic devices are discarded, generating waste containing lithium-ion batteries. In the present invention, the waste of widely used conventional lithium-ion batteries is the object to be treated.

[0040] There are no particular restrictions on the shape, structure, size, and material of lithium-ion batteries (especially lithium-ion secondary batteries). Examples of the shape of lithium-ion batteries include laminate type, cylindrical type, button type, coin type, square type, flat type, etc. Examples of the form of lithium-ion batteries include battery cells, battery modules, and battery packs. Here, a battery module means a unit formed by connecting a plurality of battery cells, which are unit batteries, together in one housing, and a battery pack means a unit formed by combining a plurality of battery modules in one housing. Further, the battery pack may be provided with a control controller or a cooling device.

[0041] Examples of lithium-ion batteries include those having a positive electrode, a negative electrode, a separator, an electrolytic solution containing an electrolyte and an organic solvent, and an outer container which is a battery case for housing the positive electrode, the negative electrode, the separator, and the electrolytic solution. Note that the lithium-ion battery may be in a state where the positive electrode and the negative electrode have fallen off.

[0042] Treat waste lithium-ion batteries by heat treatment (roasting) under temperature conditions such as 500 to 1000 °C to make valuable metals such as lithium and cobalt in the battery into a form that can be easily dissolved by acid. At this stage, organic substances such as plastics in the waste are removed. Subsequently, a crushing process is carried out using, for example, an impact crusher (such as a 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 crushed product may be screened (classified). In this case, a classified recovered product with aluminum removed to a certain extent can be obtained under the sieve. The conditions for the crushing and screening can be appropriately adopted from those conventionally known. By performing a magnetic separation process on the crushed product or the classified recovered product, some of cobalt, nickel, manganese, etc. are separated from the crushed product / classified recovered product as magnetic adherents. As a result, a granular material containing lithium (also called black mass) is obtained as a non-magnetic adherent. The conditions for magnetic separation can be appropriately adopted from those conventionally known.

[0043] The obtained granular material is leached with strong acids such as sulfuric acid, hydrochloric acid, and nitric acid. Generally, sulfuric acid is the first choice as the strong acid from the perspective of chemical cost, but hydrochloric acid is adopted in the present invention. By the above leaching, various metals contained in the granular material are dissolved, and solid-liquid separation from the negative electrode active material (graphite), etc. is carried out. Through such treatment, a hydrochloric acid leaching solution of waste containing lithium-ion batteries is obtained. The conditions for the hydrochloric acid leaching can be appropriately adopted from those conventionally known. For example, for a mixed solution obtained by immersing the granular material in hydrochloric acid at room temperature (the temperature of the solution may rise to about 60 °C naturally), the pH of the mixed solution is set to less than 1 (preferably 0.8 or less), and it is stirred for 0.25 to 2 hours. In addition, in order to improve the leaching efficiency, the granular material may be crushed before hydrochloric acid leaching.

[0044] Through the above operations, the water to be treated (hydrochloric acid leaching solution) in the method for producing the raw material liquid of the lithium compound of the present invention is generated.

[0045] <<Water to be treated>> In the method for producing a raw material solution of a lithium compound according to the present invention 1, treated water (hydrochloric acid leachate) is obtained by hydrochloric acid leaching. Since the treated water contains a large amount of hydrochloric acid, it is usually acidic. Further, it contains various metal ions dissolved in hydrochloric acid and the like. The method for producing a raw material solution of a lithium compound according to the present invention 2 uses the treated water described above as a typical treatment target, but if there is waste liquid or the like having a similar composition, the method is also applicable thereto.

[0046] Hereinafter, each component constituting the treated water will be described. <Lithium ion> The treated water contains lithium ions. Its content is not particularly limited, but as described above, typically the treated water is a hydrochloric acid leachate of lithium ion battery waste and contains a certain amount or more of lithium ions. Specifically, 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 value of the content is not particularly limited, but is, for example, 15000 ppm.

[0047] <Sodium ion> The treated water contains sodium ions. Since lithium ion batteries are basically composed of materials that do not contain sodium, sodium is mixed as an impurity, and the content of sodium ions in the treated water is usually 100 ppm or less. From the viewpoint of obtaining a lithium compound with higher purity, the content is preferably 80 ppm or less, and more preferably 60 ppm or less. In addition, the content is usually 1 ppm or more.

[0048] It is difficult to selectively remove sodium ions from the treated water, particularly to separate them from lithium ions. Since the amount of sodium ions in the treated water is usually trace as described above, by adjusting the chemicals used in each step so as not to increase the amount of sodium ions as much as possible, treated water beneficial as a raw material for producing a high-purity lithium compound can be obtained. Specifically, the mass ratio of lithium ions to sodium ions in the treated water may be adjusted to be within the range described later.

[0049] <Other metal ions> The treated water contains various metal ions other than lithium ions and sodium ions, which are derived from members of the lithium-ion battery such as electrodes, electrolytes, and casings.

[0050] Note that there are differences in the raw materials used for various members of the lithium-ion battery depending on the battery manufacturer. Also, due to differences in the method of generating the treated water from lithium-ion battery waste and variations in the operation of the processes until generation, the composition of the treated water can vary. For this reason, it is possible that a certain treated water contains a certain metal X in an amount of several thousand ppm, while another treated water does not contain metal X.

[0051] The treated water to be treated in the present invention contains, as other metal ions, typically 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. Among these, iron ions, aluminum ions, and nickel ions are often contained.

[0052] 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 treated water is, for example, 3000 ppm or more (usually 100000 ppm or less). The total content may be 11000 to 63000 ppm.

[0053] Even when the treated water contains these metal ions, the content of each individual ion is as follows. The content of magnesium ions in the treated water is, for example, 15 ppm or more (usually 1000 ppm or less). The content of magnesium ions may be 40 to 500 ppm. The calcium ion content in the water to be treated is, for example, 50 ppm or more (usually 3500 ppm or less). The calcium ion content may be 300 to 2000 ppm. The aluminum ion content in the water to be treated is, for example, 1500 ppm or more (usually 30000 ppm or less). The aluminum ion content may be 5000 to 20000 ppm. The cobalt ion content in the water to be treated is, for example, 150 ppm or more (usually 5000 ppm or less). The cobalt ion content may be 300 to 2500 ppm. The nickel ion content in the water to be treated is, for example, 300 ppm or more (usually 15000 ppm or less). The nickel ion content may be 800 to 4000 ppm. The manganese ion content in the water to be treated is, for example, 300 ppm or more (usually 10000 ppm or less). The manganese ion content may be 1000 to 8000 ppm. The iron ion content in the water to be treated is, for example, 5 ppm or more (usually 3000 ppm or less). The iron ion content may be 100 to 1500 ppm. The copper ion content in the water to be treated is, for example, 500 ppm or more (usually 15000 ppm or less). The copper ion content may be 1500 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). The zinc ion content may be 30 to 600 ppm.

[0054] <Fluoride ion> Since materials containing fluorine are widely used in the electrolytes and binders of lithium-ion batteries, the water to be treated contains fluoride ions. The fluoride ion content in the water to be treated is, for example, 1000 ppm or more. The upper limit is not particularly limited, but the content is usually 12000 ppm or less. The fluoride ion content may be 1500 to 8000 ppm.

[0055] <Chloride ion> For the leaching of the granulated product of lithium ion battery waste, a strong acid capable of dissolving various metals is used. Since it is difficult to generate gypsum even after passing through each step in the process of the present invention after acid leaching, and when crystallizing lithium hydroxide described later, the solubility of chloride salts such as calcium chloride is generally high and it is difficult to form a eutectic with lithium hydroxide, hydrochloric acid is adopted as the strong acid in the present invention. Focusing only on the leaching step, sulfuric acid is often selected from the perspective of chemical cost. However, as a result of considering the overall process from the production of the raw material liquid for producing lithium compounds to the treatment cost of the waste generated in the process, the present invention adopts hydrochloric acid. As described above, since hydrochloric acid is used in acid leaching in the present invention, the water to be treated contains a large amount of chloride ions derived from this hydrochloric acid.

[0056] Specifically, the content of chloride ions in the water to be treated is, for example, 10,000 ppm or more. The upper limit value of the content is not particularly limited, but the content is usually 200,000 ppm or less. The content of chloride ions may be 25,000 to 120,000 ppm.

[0057] <Other components> The water to be treated may contain other components. Examples of such components include phosphate ions, which are typically contained in the positive electrode material. The content of phosphate ions in the water to be treated is, for example, 500 ppm or more. The upper limit value of the content is not particularly limited, but the content is usually 10,000 ppm or less. The content of phosphate ions may be 1,000 to 5,000 ppm.

[0058] Furthermore, even when sulfuric acid is not used in acid leaching, the water to be treated often contains a trace amount of sulfuric acid. In that case, the content of sulfate ions in the water to be treated is, for example, 80 ppm or more. The upper limit value of the content is not particularly limited, but the content is usually 3,000 ppm or less. The content of sulfate ions may be 150 to 1,500 ppm.

[0059] <ph> Since the water to be treated is typically a leachate obtained by leaching granulated lithium-ion battery waste with hydrochloric acid, its liquor property is usually acidic. Specifically, the pH of the water to be treated is, for example, 0.1 to 2.5. The pH may be 0.3 to 2.0.

[0060] <<Steps in the method for producing a raw material liquid for lithium compound>> Next, various steps implemented in the method for producing a raw material liquid for a lithium compound according to the second aspect of the present invention will be described. In the second aspect of the present invention, as essential steps, Steps 1 to 4 described below are implemented, and as optional steps, Step 3', Step 5, Step α, Step β, and Step γ may be implemented.

[0061] In Steps 1 and 2, various metal ions and fluoride ions other than lithium ions and sodium ions in the water to be treated are removed by precipitation. In Step 3, calcium ions are removed including those added in Steps 1 and 2. In Step 3', the treatment liquid obtained in Step 3 is further purified and concentrated. In Step 4, cations (such as lithium ions and sodium ions) in the treatment liquid obtained in Step 3 or 3' are separated from anions and substances without charge, and water containing lithium ions is recovered. Step 5 is implemented when a chemical agent that generates ammonia (ammonium ions) is used in Step 3. Step α may be implemented for the purpose of reducing the process load of Step 4 when the treatment liquid C obtained in Step 3 contains ammonia (ammonium ions). Step β repeats Step 4 and can be implemented immediately after Step 4 or after Step 5. Step γ is performed when it is desired to completely remove calcium ions in the treatment liquid obtained in Step 4, 5, etc. Hereinafter, the details of each of these steps will be described.

[0062] <Step 1 (First reaction)> In Step 1, a calcium compound is added to the water to be treated and the pH of the water to be treated is made weakly alkaline. In this liquid state, various metal ions other than lithium ions and sodium ions (other metal ions) can be precipitated as solids. Further, the calcium compound reacts with fluoride ions and phosphate ions to form solid precipitates. Since fluoride ions cannot be sufficiently removed in Step 4, it is important to remove them in this step (and Step 2).

[0063] When 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 of lithium ions captured by the separation means (such as filter paper) 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 (usually 500 ppm or more), and then Step 1 may be carried out.

[0064] The type of calcium compound used in Step 1 is not particularly limited, but slaked lime (calcium hydroxide) is preferred. This is because by adding this, the pH of the water to be treated can be varied to weakly alkaline without adding other alkaline substances. Although fluoride ions can also be captured by an ion exchange resin, negative ions derived from the ion exchange resin are released as counterions, and the removal of these may become a problem. In actual operation, resin regeneration is also necessary. Calcium compounds, particularly slaked lime, are useful because they do not generate anions that require further removal when reacting with fluoride ions and phosphate ions to form solids.

[0065] Regarding the amount of the calcium compound used, an excessive amount is used to sufficiently remove fluoride ions and phosphate ions. If the calcium compound is slaked lime, it may be added until the pH of the water to be treated becomes weakly alkaline.

[0066] In Step 1, the pH of the water to be treated is adjusted to weakly alkaline. By setting the liquid property to this, in addition to fluoride ions and phosphate ions, other metal ions precipitate well as hydroxides, etc. When slaked lime is used as the calcium compound, adding this to the water to be treated can adjust the pH to the above level. Note that weakly alkaline preferably means a pH of 7.1 to 9.0, and more preferably 7.2 to 8.0 from the viewpoint of causing other metal ions to precipitate well.

[0067] By performing the operations described above, precipitates derived from other metal ions, etc. contained in the water to be treated are generated. This is subjected to solid-liquid separation treatment. The means for this treatment is not particularly limited, and examples include filtration and filter presses. Solids are recovered as residues by the solid-liquid separation treatment. Regarding the solids, calcium chloride is generated in Step 1, but since its solubility is high, most of it is dissolved in the liquid. The solids are mainly composed of hydroxides of other metals, calcium phosphate, and calcium fluoride, and can be reused as raw materials for smelting. On the other hand, when lithium-ion battery waste is leached with sulfuric acid, a large amount of gypsum is generated in this Step 1, increasing the industrial waste treatment cost.

[0068] By performing Step 1 described above, the treated liquid A (the liquid after the first reaction) separated by the solid-liquid separation treatment is obtained. The composition of the treated liquid A (the liquid after the first reaction) is, for example, as follows. The lithium-ion content in the treated liquid A is, for example, 800 ppm or more (usually 15,000 ppm or less). The lithium-ion content may be 900 to 8,000 ppm. The sodium-ion content in the treated 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. Note that the 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 liquid A are each, for example, 500 ppm or less, preferably 100 ppm or less, and more preferably 60 ppm or less. The content of calcium ions in treatment liquid A is, for example, 500 ppm or more (usually 15000 ppm or less). The content of calcium ions may be 1500 to 8000 ppm. The content of fluoride ions in 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 chloride ions in treatment liquid A is, for example, 2000 ppm or more (usually 80000 ppm or less). The content of chloride ions may be 4000 to 30000 ppm. The content of phosphate ions in treatment liquid A is, for example, 1000 ppm or less, preferably 300 ppm or less, and more preferably 50 ppm or less. The content of sulfate ions in treatment liquid A is, for example, 800 ppm or less, preferably 200 ppm or less, and more preferably 100 ppm or less.

[0069] <Step 2 (Second Reaction)> In step 2, an alkaline substance is added to the treatment liquid A obtained in step 1 to make the pH of the water to be treated alkaline. In this liquid state, various metal ions other than lithium ions and sodium ions (other metal ions) can be further precipitated as solids. If the solid-liquid separation treatment is not carried out in step 1, the substances precipitated in step 1 (especially precipitates containing amphoteric metals such as Zn and Al) may redissolve due to the change in the liquid state. To prevent such a situation, it is important to carry out the solid-liquid separation treatment in step 1.

[0070] The alkaline substance used in Step 2 is a substance that dissolves in water to exhibit alkalinity, such as slaked lime, ammonia, and sodium hydroxide. Among these, slaked lime is preferred because it does not form a complex with transition metals and ammonia to promote dissolution, and it does not add metals that are difficult to remove to the treatment liquid A, which is the treatment target in Step 2. When slaked lime is used in Step 2, if there are fluoride ions or phosphate ions that could not be completely removed in Step 1 in the treatment liquid A, they can also be removed.

[0071] Regarding the usage amount of the alkaline substance, the alkaline substance may be added until the pH of the water to be treated becomes alkaline.

[0072] In Step 2, the pH of the treatment liquid A is adjusted to be alkaline by adding the alkaline substance. By making the liquid property like this, other metal ions (the ones that remained without being removed in Step 1) precipitate well as hydroxides, etc. Note that alkalinity is preferably pH 9.8 - 13.0, and from the viewpoint of well precipitating other metal ions, it is more preferably 10.0 - 11.5.

[0073] By carrying out the operations described above, precipitates derived from other metal ions, etc. contained in the treatment liquid A are generated. This is subjected to solid-liquid separation treatment. The means for this treatment is not particularly limited, and examples include filtration and filter press. Note that since most of the precipitate-forming substances such as metal ions were removed in Step 1, the residue generated in the solid-liquid separation treatment in Step 2 is in a very small amount.

[0074] By carrying out Step 2 described above, the treatment liquid B (the liquid after the second reaction), which has been separated by solid-liquid separation treatment, is obtained. The composition of the treatment liquid B (the liquid after the second reaction) is, for example, as follows. The content of lithium ions in the treatment liquid B is, for example, 500 ppm or more (usually 12000 ppm or less). The content of lithium ions may be 800 - 8000 ppm. The sodium ion content in 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. Note that the 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 liquid B are each, for example, 100 ppm or less, preferably 50 ppm or less, and more preferably 20 ppm or less. The calcium ion content in treatment liquid B is, for example, 400 ppm or more (usually 20000 ppm or less). The calcium ion content may be 1000 - 8000 ppm. The fluoride ion content in treatment liquid B is, for example, 100 ppm or less, preferably 80 ppm or less, and more preferably 40 ppm or less. The chloride ion content in treatment liquid B is, for example, 2000 ppm or more (usually 80000 ppm or less). The chloride ion content may be 4000 - 30000 ppm. The phosphate ion content in treatment liquid B is, for example, 1000 ppm or less, preferably 300 ppm or less, and more preferably 50 ppm or less. The sulfate ion content in treatment liquid B is, for example, 500 ppm or less, preferably 150 ppm or less, and more preferably 80 ppm or less.

[0075] <Step 3 (the third reaction)> In the production method of the present invention, in step 3, an oxalate ion source and / or a carbonate ion source is added to the treatment liquid B obtained in step 2. Calcium oxalate and calcium carbonate formed by the reaction of oxalate ions and carbonate ions with calcium ions have low solubility and precipitate well, so they can be easily removed by solid-liquid separation treatment. Also, calcium carbonate may be sold as a product or reused as the calcium compound used in step 1.

[0076] In the oxalate ion source and carbonate ion source, counter cations other than protons may remain in the liquid and become impurities. Therefore, oxalic acid and carbonic acid in which the counter cation is a proton, and ammonium oxalate, ammonium carbonate, and ammonium bicarbonate which are ammonium ions (which become alkaline and volatile ammonia) are preferred. Among these, ammonium carbonate and ammonium bicarbonate are particularly preferred because they can be easily dissipated as carbon dioxide gas when they become excessive without reacting with calcium ions.

[0077] By step 3, calcium (both the one originally present in the water to be treated and the ones added in steps 1 and 2) can be precipitated and removed. The usage amount of the oxalate ion source and / or carbonate ion source is preferably 1 to 10 molar times, more preferably 1 to 4 molar times, relative to Ca in the treatment liquid B, from the viewpoint of sufficiently precipitating calcium ions.

[0078] By adding the oxalate ion source and / or carbonate ion source, the liquid property of the treatment liquid B which became alkaline in step 2 changes to the lower pH side. If the solid-liquid separation treatment is not carried out in step 2, the substance precipitated in step 2 may redissolve due to the change in liquid property. In order to prevent such a situation, it is important to carry out the solid-liquid separation treatment in step 2.

[0079] The reaction pH in step 3 (the pH of the liquid obtained by adding the oxalate ion source and / or carbonate ion source to the treatment liquid B) is, for example, 8 to 12.5, preferably 8.5 to 10. The reaction time is usually 5 minutes or more, preferably 45 minutes or more (usually 90 minutes or less).

[0080] By adding the oxalate ion source and / or carbonate ion source, calcium ions form a precipitate, and then a solid-liquid separation treatment is carried out to obtain a treatment liquid C. The specific means of the solid-liquid separation treatment is the same as that in the case of the solid-liquid separation treatment in step 1. Also, when a carbonate ion source is used in step 3, the calcium carbonate produced can be reused as the calcium compound in step 1 and the like.

[0081] By carrying out Steps 1 to 3, almost all metal ions other than lithium ions and sodium ions in the water to be treated, that is, other metal ions, are removed, and furthermore, most of the anionic components are removed except for chloride ions. As a result, lithium ions are dissolved in water in the form of a salt (dissociated) with chloride ions. Since lithium chloride has high solubility, the recovery loss of lithium ions up to Step 3 can be minimized.

[0082] The composition of the treatment liquid C (the liquid after the third reaction) obtained in Step 3 is, for example, as follows. The content of lithium ions in the treatment liquid C is, for example, 500 ppm or more (usually 10,000 ppm or less). The content of lithium ions may be 600 to 5,000 ppm. The content of sodium ions in the treatment liquid C is, for example, 50 ppm or less. The content of sodium ions is preferably 40 ppm or less, and more preferably 30 ppm or less. Note that the 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 the treatment liquid C are each, for example, 100 ppm or less, preferably 50 ppm or less, and more preferably 10 ppm or less. The content of fluoride ions in the treatment liquid C is, for example, 100 ppm or less, preferably 80 ppm or less, and more preferably 40 ppm or less. The content of chloride ions in the treatment liquid C is, for example, 2,000 ppm or more (usually 50,000 ppm or less). The content of chloride ions may be 4,000 to 20,000 ppm. The content of phosphate ions in the treatment liquid C is, for example, 1,000 ppm or less, preferably 300 ppm or less, and more preferably 50 ppm or less. The content of sulfate ions in the treatment liquid C is, for example, 500 ppm or less, preferably 150 ppm or less, and more preferably 80 ppm or less. When using a chemical that generates ammonia in Step 3, the treatment liquid C contains ammonia (ammonium ions). The ammonium ion content in the treatment liquid C is, for example, 200 to 10,000 ppm.

[0083] <Step α> When using a chemical that generates ammonia (ammonium ions) in Step 2 or 3, the treatment liquid C obtained in Step 3 may contain ammonium ions. In this case, before performing Step 3' or 4 described later, as Step α for the treatment liquid C, ammonia stripping similar to Step 5 may be performed. When the treatment liquid C with a reduced ammonium ion content is fed to Step 4 (bipolar electrodialysis), the electricity consumed for the movement of ammonium ions is reduced, which is desirable in terms of cost.

[0084] <Step 3'> Nanofiltration and reverse osmosis membrane treatment may be performed on the treatment liquid C obtained in Step 3 (or obtained by subsequently performing Step α) (Step 3').

[0085] By nanofiltration, polyvalent ions other than lithium ions (and sodium ions) can be removed from the treatment liquid C (the liquid after the third reaction). And in order to concentrate the obtained permeate, concentration by a reverse osmosis membrane (RO membrane) is performed.

[0086] The nanofiltration membrane is typically a cross-flow type filter equipped with a semi-permeable membrane made of resin, and is configured to be able to remove polyvalent ions. In particular, the inventor has found that it is excellent in the ability to remove polyvalent ions and allow Li to permeate in the acidic region. Specific examples of nanofiltration membranes include poly(piperazine) - based nanofiltration membranes (NF270 manufactured by DOW Chemical) and polyamide - based nanofiltration membranes (e.g., NF90 manufactured by DOW Chemical), etc., which are commercially available. Among these, poly(piperazine) - based nanofiltration membranes are excellent in the ability to remove polyvalent ions and allow Li to permeate.

[0087] When the pH of the treatment liquid C (the liquid after the third reaction) during nanofilter filtration is set to 1 to 11, particularly pH 1.2 to 4, the distribution of polyvalent ions such as calcium ions into the permeate can be prevented, high-purity Li can be recovered into the permeate, and the remaining CO2 can also be separated.

[0088] Subsequently, the permeate obtained by nanofilter filtration is subjected to reverse osmosis membrane treatment. This treatment only needs to be able to concentrate the permeate, and a conventionally known cross-flow type reverse osmosis membrane can be used without particular limitation. There is no particular limitation on the pH of the permeate during reverse osmosis membrane treatment, but for example, it may be in the range of pH 1 to 11.

[0089] The composition of the concentrated liquid obtained in Step 3' is as follows. The lithium ion content in the concentrated liquid is, for example, 400 ppm or more (usually 6000 ppm or less). The lithium ion content may be 600 to 2000 ppm. The sodium ion content in the concentrated liquid is, for example, 300 ppm or less. The sodium ion content is preferably 150 ppm or less, more preferably 100 ppm or less. Note that the 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 concentrated liquid are each, for example, 100 ppm or less, preferably 50 ppm or less, more preferably 20 ppm or less. The fluoride ion content in the concentrated liquid is, for example, 50 ppm or less, preferably 20 ppm or less, more preferably 5 ppm or less. The chloride ion content in the concentrated liquid is, for example, 120000 ppm or less (usually 5000 ppm or more). The chloride ion content may be 8000 to 50000 ppm. The phosphate ion content in the concentrated liquid is, for example, 100 ppm or less, preferably 20 ppm or less, more preferably 5 ppm or less. The content of sulfate ions in the concentrated solution is, for example, 500 ppm or less, preferably 300 ppm or less, and more preferably 100 ppm or less. In cases where a chemical agent that generates ammonium ions was used in Step 2 or 3 (and Step α was not carried out), the concentrated solution contains ammonium ions. The content thereof is, for example, 1500 ppm or more (usually 40000 ppm or less). The content of ammonium ions may be 3000 to 15000 ppm.

[0090] <Step 4> In Step 4, electrodialysis using a bipolar electrodialysis apparatus is carried out on the treatment liquid C obtained in Step 3 or the concentrated solution obtained in Step 3'. Specifically, it is as follows.

[0091] In bipolar electrodialysis, a known bipolar electrodialysis apparatus 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 apparatus 10 having the configuration shown in FIG. 1 is used.

[0092] In FIG. 1, the anode 11 is arranged on the leftmost side, the left-end bipolar membrane 1 is arranged adjacent to its right, the left-side cation exchange membrane 22 is arranged adjacent to its right, the central bipolar membrane 3 is arranged adjacent to its right, the right-side cation exchange membrane 24 is arranged adjacent to its right, the right-end bipolar membrane 5 is arranged adjacent to its right, and the cathode 12 is arranged on the rightmost side. And flow paths (1) to (4) are formed between these membranes.

[0093] From the treated water tank 32, the treatment liquid C obtained in step 3 or the concentrated liquid obtained in step 3' (hereinafter also referred to as "treatment liquid C etc.") is supplied to the flow paths (1) and (3). When the power supply of the bipolar electrodialysis device 10 is turned on, a current flows substantially perpendicular to the cation exchange membrane and the bipolar membrane, and only the cations in the treatment liquid C etc. pass through the cation exchange membrane and move toward the cathode 12 on the right side of FIG. 1. As a result, the cations in the treatment liquid C etc. are separated from substances with other charges. Focusing on the flow path (1), for the cations that have passed through the left cation exchange membrane 22, the central anion exchange layer 3a of the central bipolar membrane 3 faces the left cation exchange membrane 22, and OH - is supplied to the flow path (2) and forms hydroxides with the cations. Then, the liquid flowing through the flow path (2) is recovered into the alkali liquid tank 34.

[0094] In FIG. 1, an example is described in which two sets of the combination of the central bipolar membrane 3 and the left cation exchange membrane 22 are arranged while providing the leftmost bipolar membrane 1. On the other hand, the number of sets of this combination is not limited, and for example, the leftmost bipolar membrane 1 may be provided while setting the number of sets to 10 to 200 sets.

[0095] Next, in the three-chamber method, the bipolar electrodialysis device 10 also includes an anion exchange membrane, which is preferable because anions can be more reliably separated. The configuration of the bipolar electric device 10 in this case is, for example, as shown in FIG. 2.

[0096] In FIG. 2, the anode 11 is arranged on the leftmost side, the leftmost bipolar membrane 1 is arranged adjacent to its right, the left anion exchange membrane 2 is arranged adjacent to its right, the left cation exchange membrane 2' is arranged adjacent to its right, the central bipolar membrane 3 is arranged adjacent to its right, the right anion exchange membrane 4 is arranged adjacent to its right, the right cation exchange membrane 4' is arranged adjacent to its right, the rightmost bipolar membrane 5 is arranged adjacent to its right, and the cathode 12 is arranged on the rightmost side. Then, flow paths (1) to (4') are formed between these membranes.

[0097] When the bipolar electrodialysis apparatus 10 is powered on, the treatment liquid C and the like flow from the water to be treated tank 6 into the flow paths (2) and (4). In the flow paths, anions (such as chloride ions) in the concentrated liquid move toward the anode 11. The behavior of cations and substances without charge is the same as in the two-chamber method.

[0098] Although it is repetitive as the description content, for the cations that have passed through the left cation exchange membrane 2', in the central bipolar membrane 3, the central anion exchange layer 3a and the left cation exchange membrane 2' face each other, and OH - is supplied to the flow path (2'), and forms a hydroxide with the cations. Then, the liquid (alkali liquid) flowing through the flow path (2') is recovered into the alkali liquid tank 9.

[0099] Regarding the anions, when focusing on the flow path (2), they pass through the left anion exchange membrane 2 and enter the flow path (1), where H + is supplied from the left cation exchange layer 1b of the leftmost bipolar membrane 1. As a result, for example, hydrochloric acid is regenerated and recovered into the acid liquid tank 7.

[0100] Figure 2 shows an example in which two sets of the combination of the leftmost bipolar membrane 1, the left anion exchange membrane 2, and the left cation exchange membrane 2' are arranged and the rightmost bipolar membrane 5 is provided. On the other hand, the number of sets of the combination (the membrane structure in which the three types of membranes are repeatedly arranged) is not limited. For example, the number of sets can be 10 to 200 sets while providing the rightmost bipolar membrane 5.

[0101] In addition, the various conditions of the electrodialysis process are not limited. One example is as follows. Voltage of the current applied in bipolar electrodialysis: 25 to 35 V Current applied in bipolar electrodialysis: maximum 4.4 A Time for applying the current: Appropriately changed according to the lithium ion concentration in the target alkali liquid, the amount of the treatment liquid C to be treated, etc. Operating temperature of bipolar electrodialysis (temperature of the treatment liquid): Considering the influence on various membranes such as anion exchange membranes used in this embodiment, the temperature can be set to room temperature, for example, 2 to 40°C.

[0102] In the alkali solution obtained in Step 4, impurities other than lithium ions and sodium ions (and ammonium ions) are well reduced (other metal ions are well reduced by Step 2), and lithium ions and sodium ions are concentrated. Specifically, the composition of the alkali solution is as follows.

[0103] The content of lithium ions in the alkali solution is, for example, 2000 ppm or more (usually 25000 ppm or less). The content of lithium ions may be 3000 to 10000 ppm. The content of sodium ions in the alkali solution is, for example, 800 ppm or less. The content of sodium ions is preferably 500 ppm or less, more preferably 300 ppm or less. Note that the 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 alkali solution are each, for example, 100 ppm or less, preferably 50 ppm or less, and more preferably 10 ppm or less. The content of fluoride ions in the alkali solution is, for example, 50 ppm or less, preferably 30 ppm or less, and more preferably 20 ppm or less. In bipolar electrodialysis, fluoride ions seem to permeate through the cation exchange membrane, and it is difficult to reduce fluoride ions in Step 4. The content of chloride ions in the alkali solution is, for example, 12000 ppm or less (usually 100 ppm or more). The content of chloride ions may be 500 to 10000 ppm. The content of phosphate ions in the alkali solution 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 alkaline solution is, for example, 200 ppm or less, preferably 100 ppm or less, and more preferably 60 ppm or less. When a chemical agent that generates ammonium ions is used in Step 3 (and Step α is not carried out), the alkaline solution contains ammonium ions. The content is, for example, 3000 ppm or more (usually 60000 ppm or less). The content of ammonium ions may be 4500 to 30000 ppm.

[0104] Using the alkaline solution obtained in Step 4, which mainly contains lithium ions and substantially does not contain ammonia, battery-grade lithium carbonate and lithium hydroxide can be produced as described later. That is, the alkaline solution is useful as a raw material solution for producing lithium compounds. When the alkaline solution contains ammonium ions, it is removed in Step 5 described later.

[0105] In addition, when bipolar electrodialysis is a three-chamber method, the acid solution contains anions that were not removed (could not be partitioned) up to Step 3, and the anion is typically chloride ion. Theoretically, the acid solution should not contain lithium ions, but in reality, a trace amount is contained. When the present invention is carried out by recycling this acid solution as hydrochloric acid for leaching the granulated product of lithium-ion battery waste, cost reduction can be achieved, and the lithium ions that have entered the acid solution can also be recovered.

[0106] <Step 5> When a chemical agent that generates ammonium ions is used in Step 2 or 3, the alkaline solution obtained in Step 4 contains ammonium ions (ammonia), so this is removed in Step 5 (ammonia stripping).

[0107] 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 has a stronger alkalinity), in the alkaline solution, ammonia exists in a higher proportion in the free form rather than in ionic form and can be easily removed by volatilization simply by heating or reducing the pressure. That is, there is no need to add any chemicals to the alkaline solution for ammonia removal.

[0108] By carrying out the ammonia stripping in Step 5, a treatment liquid with a reduced ammonium ion content is obtained. Also, when ammonia is removed by volatilization, some water, which is the solvent, also evaporates to some extent, so other components are concentrated.

[0109] Specifically, the composition of the stripping treatment liquid obtained in Step 5 is as follows. The content of ammonium ions in the stripping treatment liquid is, for example, 800 ppm or less, preferably 400 ppm or less. The content of ammonium ions in the stripping treatment liquid is usually 5 ppm or more. The content of lithium ions in the stripping treatment liquid is, for example, 2500 ppm or more (usually 30000 ppm or less). The content of lithium ions may be 3500 - 15000 ppm. The content of sodium ions in the stripping treatment liquid is, for example, 800 ppm or less. The content of sodium ions is preferably 500 ppm or less, more preferably 350 ppm or less. The 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 liquid are each, for example, 100 ppm or less, preferably 50 ppm or less, more preferably 10 ppm or less. The content of fluoride ions in the stripping treatment liquid 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 stripping treatment liquid is, for example, 15000 ppm or less (usually 150 ppm or more). The content of chloride ions may be 500 to 12000 ppm. The content of phosphate ions in the stripping treatment liquid 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 stripping treatment liquid is, for example, 200 ppm or less, preferably 100 ppm or less, and more preferably 70 ppm or less.

[0110] <Process β> Process β is the same bipolar electrodialysis as Process 4. For example, it can be carried out when the content of anions in the obtained alkaline liquid is high after carrying out Process 4 once. In addition, in order to reduce the power consumption, it is desirable to carry out Process β after Process 5 in which ammonia is removed.

[0111] <Process γ> When the content of calcium ions is high in the alkaline liquid or the stripping treatment liquid obtained in Process 4 or 5, this Process γ may be carried out. In this Process γ, the above-mentioned alkaline liquid or the like is passed through a chelating resin to remove calcium ions. Examples of the chelating resin include chelating resins having iminodiacetic acid as a functional group. Also, it is desirable to substitute the cation part of the chelating resin with lithium ions so as not to remove lithium ions even by passing the liquid.

[0112] <Raw material liquid for lithium compound production> The manufacturing method of the raw material liquid for lithium compound of the present invention described above is implemented, and the treatment liquid obtained through the final process (process 4 or any subsequent optional process if implemented) contains lithium ions at a high concentration, and other contained metal ions are about a small amount of sodium ions. Lithium and sodium are homologous elements, but there is a significant difference in terms of the solubility of their hydroxides and compounds with other anions. Utilizing this characteristic, a lithium compound with high purity can be manufactured from the treatment liquid. That is, the treatment liquid is useful as a raw material liquid for manufacturing lithium compounds. Note that the ratio of the content of lithium ions to sodium ions (lithium ions / sodium ions) in the treatment liquid is, for example, 20 or more. This ratio is usually 100 or less.

[0113] [Method for manufacturing lithium hydroxide powder] The raw material liquid obtained by the manufacturing method of the raw material liquid for lithium compound of the present invention contains lithium ions as described above and has a low content of other impurities. The anions contained in the raw material liquid are chloride ions and hydroxide ions supplied in process 4 etc., and the content of the latter is sufficiently large. Therefore, the pH of the raw material liquid is usually 10 or more (usually 13 or less).

[0114] When the water in this raw material liquid is evaporated, lithium ions can be crystallized as lithium hydroxide, which is a compound with hydroxide ions as the counter anion. Note that the raw material liquid also contains a certain amount of sodium ions, but sodium hydroxide has a 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 the condition that lithium hydroxide crystallizes and sodium hydroxide does not crystallize.

[0115] Specifically, for example, crystallization can be carried out under the following conditions using a known evaporation concentration device. Evaporation concentration device: Either a steam heating type or a heat pump type concentration device can be used. Internal pressure in the evaporator: 0.1 - 0.8 atm Heating temperature (temperature of the heated production raw material liquid): 60 to 95 °C Treatment time: Can be adjusted as appropriate to achieve the desired amount of lithium hydroxide crystallization

[0116] The condensed water obtained by this evaporation concentration can be used as dilution water in the hydrochloric acid leaching process, or can be treated as wastewater. Also, for evaporation concentration, it is sufficient to obtain a concentrated liquid with increased lithium ion concentration but without lithium hydroxide crystallization in one device, and this concentrated liquid can be treated in another device to crystallize lithium hydroxide.

[0117] For the concentrated liquid (lithium-containing water) containing crystallized lithium hydroxide, solid-liquid separation (e.g., suction filtration) can be performed, and washing may be carried out as necessary. The washing can be with water or with a separately prepared saturated lithium hydroxide aqueous solution. Then, if the washed lithium hydroxide is dried, lithium hydroxide powder suitable for battery grade can be obtained. Note that recrystallization may be performed on the obtained lithium hydroxide powder. Even higher purity lithium hydroxide powder can be obtained.

[0118] The composition of the lithium hydroxide powder obtained in the present invention is specifically as follows. The lithium content in the lithium hydroxide powder is, for example, 16 to 19% by mass. The sodium content in the lithium hydroxide powder is, for example, 4000 ppm or less, preferably 30 ppm or less. The contents of iron, aluminum, nickel, copper, calcium, magnesium, cobalt, manganese, zinc, phosphate, and ammonia in the lithium hydroxide powder are each, for example, 80 ppm or less, preferably 10 ppm or less. The fluorine content in the lithium hydroxide powder is, for example, 200 ppm or less, preferably 30 ppm or less. The chloride ion content in the lithium hydroxide powder is, for example, 15000 ppm or less, preferably 400 ppm or less, more preferably 30 ppm or less. The content of sulfate ions in the lithium hydroxide powder is, for example, 2000 ppm or less, preferably 50 ppm or less. The remaining composition of the lithium hydroxide powder is oxygen, hydrogen, and inevitable impurities.

[0119] In addition, the liquid portion obtained by the above crystallization operation contains lithium ions that did not crystallize. Ammonium carbonate may be added to this liquid and reacted with the lithium ions to form lithium carbonate. The lithium carbonate-containing liquid thus obtained can be returned to any of the steps 1 to 4 in the method for producing the raw material liquid of the lithium compound of the present invention.

[0120] [Method for producing lithium carbonate powder] In addition, lithium carbonate can be produced by bringing the raw material liquid obtained by the method for producing the raw material liquid of the lithium compound of the present invention into contact 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, that is, by blowing carbon dioxide gas into the above raw material liquid in water. At this time, pressurization may be performed to prevent the volatilization of carbon dioxide gas.

[0121] Regarding the formation of lithium carbonate and sodium carbonate, since the solubility of lithium carbonate is lower than that of sodium carbonate, when carbonation is carried out, only lithium carbonate precipitates as a solid in water.

[0122] This is subjected to solid-liquid separation, washed if necessary, such as by water washing, and dried, whereby lithium carbonate powder suitable for battery grade separated from sodium and other impurities can be obtained. The obtained lithium carbonate powder may be recrystallized. Even higher purity lithium carbonate powder can be obtained.

[0123] The composition of the lithium carbonate powder obtained in the present invention is specifically as follows. The content of lithium in the lithium carbonate powder is, for example, 18 to 20% by mass. The sodium content in the lithium carbonate powder is, for example, 50 ppm or less. The contents of iron, aluminum, nickel, copper, calcium, magnesium, cobalt, manganese, zinc, and phosphate in the lithium carbonate powder are, respectively, for example, 80 ppm or less, preferably 20 ppm or less. The fluoride content in the lithium carbonate powder is, for example, 400 ppm or less. The chloride ion content in the lithium carbonate powder is, for example, 300 ppm or less. The sulfate ion content in the lithium carbonate powder is, for example, 50 ppm or less. The remaining composition of the lithium carbonate powder is oxygen, carbon, and inevitable impurities.

Examples

[0124] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples. Also, the following comparative examples do not mean conventional examples.

[0125] In the following examples and comparative examples, various measurements were performed as follows. · Content of metal ions other than Na ions: Measured using an ICP emission spectrometer SPS-5100 manufactured by Hitachi High-Tech Sciences and an ICP mass spectrometer Agilent 7900 ICP-MS manufactured by Agilent Technologies. · Content of Na ions: Measured using a polarized Zeeman atomic absorption photometer ZA3300 manufactured by Hitachi High-Tech Sciences. · pH: Measured at 25 °C using a pH meter · electrode HORIBA D-73. · Nitrate ion concentration: Measured using an ion chromatograph Tosoh IC-8100EX. · Ammonium ion concentration: Measured using an ion chromatograph Tosoh IC-8100EX. · Fluoride ion concentration: Measured using an ion chromatograph Tosoh IC-8100EX. · Chloride ion concentration: Measured using ion chromatograph Tosoh IC-8100EX. · Phosphate ion concentration: Measured using ion chromatograph Tosoh IC-8100EX. · Sulfate ion concentration: Measured using ion chromatograph Tosoh IC-8100EX. · Electrical resistance: Equilibrated in 0.5 mol / L saline solution and measured at 25 °C by alternating current. · ORP (oxidation-reduction potential): Measured at 25 °C using electrode HORIBA D-73. · EC (electrical conductivity): Measured using EC meter and electrode TOA DKK CM-31P.

[0126] [Example 1] <Generation of treated water> 150 g of black mass (non-magnetically attached material) after incineration treatment, crushing and magnetic separation of a lithium-ion battery was crushed by hitting with a hammer. Then, 250 mL of pure water was added, and further 145 mL of 37% by mass hydrochloric acid was added. This solution (pH: 0.5) was stirred at a temperature of 20 - 60 °C for 0.5 hours (starting from room temperature, but rising to 60 °C due to the heat of neutralization. Then, it naturally cooled and the temperature dropped to 20 °C), pure water was added to make the volume 1 L, and solid-liquid separation was carried out. The composition of the obtained hydrochloric acid leaching solution, together with the compositions of the sulfuric acid leaching solution and nitric acid leaching solution obtained by performing the same operations as above except that hydrochloric acid was changed to sulfuric acid or nitric acid, is shown in Table 1 below.

[0127]

Table 1

[0128] <Step 1> The hydrochloric acid leaching solution obtained above was mixed with the hydrochloric acid leaching solution obtained by hydrochloric acid leaching another black mass in the same manner as above. The obtained mixed solution (pH: 0.5) was diluted 4-fold with pure water and then adjusted to pH 7.5 with slaked lime. When this solution was stirred for 0.5 hours, solids were formed. The mixed solution with solids was subjected to solid-liquid separation treatment with a filter press to obtain treatment liquid A (the liquid after the first reaction).

[0129] <Engineering 2> Slaked lime slurry was added to the treatment liquid A (the liquid after the first reaction) to adjust the pH to 10.5. After stirring this liquid for 60 minutes, the precipitate was filtered with a bag filter to obtain the treatment liquid B (the liquid after the second reaction) as the filtrate.

[0130] <Engineering 3> Ammonium carbonate was added to the treatment liquid B (the liquid after the second reaction) to a concentration of 20 g / L and stirred. The amount of ammonium carbonate used was 2 molar times that of calcium in the treatment liquid B. After stirring for 60 minutes, the pH of the solution was 9.3. After the stirring, the precipitate was filtered off with a filter press to obtain the treatment liquid C (the liquid after the third reaction) as the filtrate.

[0131] The compositions of the treatment liquids A - C obtained in the above steps 1 - 3 are shown in Table 2 below.

Table 2

[0132] <Engineering 3'-1 (Nanofiltration)> A 37 mass% hydrochloric acid aqueous solution was added to 40 L of the treatment liquid C (the liquid after the third reaction) with a pH of 9 to adjust the pH to 2.5. This liquid was treated with an NF270 - 4040 membrane (a cross - flow type filter) manufactured by DOW Chemical. The separation operation was carried out at a constant operating pressure of 1 MPa for the device, separating it into a permeate and a concentrate.

[0133] The results of the separation operation are shown in Table 3 below.

Table 3

[0134] <Engineering 3'-2 (RO treatment)> The permeate obtained in Engineering 3'-1 was treated with SW30 - 4040 manufactured by DOW Chemical. The separation operation was carried out at a constant operating pressure of 6 MPa for the device, separating it into a permeate and a concentrate.

[0135] The results of the separation operation are shown in Table 4 below.

Table 4

[0136] <Step 4> 8 L of the concentrate obtained in Step 3'-2 was fed to the bipolar electrodialysis apparatus (manufactured by Astom, EX3B) shown in Figure 2. For the bipolar membrane, Astom BP1-EX was used; for the cation exchange membrane, Astom CMB was used; and for the anion exchange membrane, Astom AHA (electrical resistance was 4.1 Ω cm 2 ) was used. Ten sheets each of the anion exchange membrane and the cation exchange membrane, and eleven sheets of the bipolar membrane were used, and the membrane repeating structure of the anion exchange membrane, the cation exchange membrane, and the bipolar membrane was 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 .

[0137] 8 L of the above-mentioned concentrate was added to the water to be treated tank in the initial state, 1.5 L of pure water was added to the acid solution tank in the initial state, and 2 L of pure water was also added to the alkali recovery tank. In the electrodialysis operation, the applied voltage was kept constant at 35 V. The current value was automatically controlled within 0 to 4.4 A. The treatment time was 8.6 hours. The desalting operation was continued until the electrical conductivity of the tail liquid (the liquid in the water to be treated tank) was less than 0.5 mS / cm.

[0138] The compositions of the alkali solution and the acid solution obtained in Step 4 above are shown in Table 5 below.

Table 5

[0139] <Steps 5 and γ> 1.3 L of the recovered alkali solution obtained in the bipolar process was fed into a low-temperature high-vacuum ammonia removal device. The ammonia removal operation was automatically controlled at a stripping temperature of 50°C and a vacuum pressure of 50 kPa. All 1.0 L of the obtained stripping treatment solution was passed through a chelating resin, Krestperle CH112 manufactured by Kureha, in the Li form to remove metal ions other than alkali metals remaining in the stripping treatment solution.

[0140] The compositions of the stripping treatment solution and the solution after chelating resin treatment obtained by the above operations are shown in Table 6 below.

Table 6

[0141] <Production of Lithium Hydroxide Powder> 1.0 L of the solution after chelating resin treatment was fed into a vacuum evaporation concentration device (NVC-2000 manufactured by EYELA), and evaporation concentration was carried out under automatic control at an evaporation temperature of 85°C and a vacuum pressure of 220 hPa. As a result, lithium hydroxide was crystallized.

[0142] The crystals obtained from the concentration treatment were collected by suction filtration, and the crystals were washed with a saturated lithium hydroxide aqueous solution (lithium hydroxide washing solution) prepared at room temperature to obtain crude lithium hydroxide.

[0143] A part of the obtained crude lithium hydroxide crystals was redissolved in pure water and subjected to a crystallization operation. Specifically, it was fed into a vacuum evaporation concentration device (NVC-2000 manufactured by EYELA), and evaporation concentration was carried out under automatic control at an evaporation temperature of 85°C and a vacuum pressure of 220 hPa. The crystals obtained from the concentration treatment were collected by suction filtration, and the crystals were washed with a saturated lithium hydroxide solution (lithium hydroxide washing solution) prepared at room temperature and dried at 70°C for 3 hours to obtain purified lithium hydroxide powder.

[0144] The filtrate (referred to as concentrated mother liquor) obtained by suction filtration in the two evaporation concentration (crystallization) operations and the lithium hydroxide washing solution were mixed above, and then ammonium carbonate was added to form lithium carbonate, followed by solid-liquid separation treatment, water washing, and drying to recover lithium carbonate powder.

[0145] The compositions of the crude lithium hydroxide powder, purified lithium hydroxide powder, and lithium carbonate powder obtained by the above operations are shown in Table 7 below. [Table 7]

[0146] In the chelate resin-treated solution obtained in the above step γ, since metals other than Li and Na were sufficiently removed, a crude lithium hydroxide powder with a low content of these impurity metals was obtained. Further, by subjecting the powder to recrystallization, a high-purity purified lithium hydroxide powder in which precipitation of hydroxides of impurity metals did not occur and various impurity elements such as Na were sufficiently removed was obtained.

[0147] [Comparative Example 1] The sulfuric acid leachate of lithium ion waste was diluted 2-fold with pure water to 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.

[0148] 1 g of an 11% by mass aqueous NaSH solution was added to the obtained diluted solution and mixed at room temperature for 30 minutes (pH: 0.96, ORP: 307 mV). Subsequently, 3.7 g of slaked lime was added and mixed at room temperature for 30 minutes (pH: 3.73, ORP: 288 mV). Subsequently, 23 g of a 28% by mass aqueous ammonia solution was added, and 1.8 g of an 11% by mass aqueous NaSH solution was added again and mixed at room temperature for 30 minutes (pH: 8.9, ORP: -53 mV).

[0149] The obtained neutralized solution was filtered under reduced pressure. The composition of the obtained filtrate is shown in Table 8 below. [Table 8]

[0150] Since a drug containing sodium was used, the amount of Na in the post-treatment liquid (the filtrate obtained by filtering the neutralized liquid) became quite high. It is difficult to remove this. Even if treated water from which metal ions other than lithium and sodium have been removed is obtained from this post-treatment liquid, when lithium is crystallized as lithium hydroxide or converted to lithium carbonate, a considerable amount of sodium hydroxide or sodium carbonate is generated, and it is difficult to obtain a powder of a high-purity (low sodium content) lithium compound.

[0151] [Reference Example 1 and Comparative Example 2] <Generation of water to be treated> 150 g of black mass (non-magnetically attached matter) after incineration treatment, crushing, and magnetic separation of a lithium-ion battery, which was different from that used in Example 1, was crushed by hitting with a hammer. 250 mL of pure water was added thereto, and 145 mL of 37 mass% hydrochloric acid was further added. This solution (pH: 0.5) was stirred at a temperature of 20 to 60 °C for 0.5 hours (starting from room temperature but rising to 60 °C due to neutralization heat etc., and then naturally releasing heat and dropping to 20 °C), pure water was added to make the volume 1 L, and solid-liquid separation was carried out. The hydrochloric acid leachate thus obtained was used as the water to be treated in subsequent treatments. The composition of the water to be treated, together with the composition of the sulfuric acid leachate obtained by performing the same operations as above except that hydrochloric acid was changed to sulfuric acid, is shown in Table 9 below.

[0152]

Table 9

[0153] (Reference Example 1) The same steps 1 to 3 as in Example 1 were carried out on the hydrochloric acid leachate. As a result, 15.3 g of residue was generated by filtration in step 1 in terms of dry weight. The residue is mainly composed of metal hydroxides such as Co, Ni, Cu, calcium phosphate, and calcium fluoride, and can be reused as a smelting raw material. The amount of residue generated during the filtration in Step 2 was as little as 0.01 g in dry weight. In Step 3, 8.79 g of residue was generated by filtration. This residue was calcium carbonate with high purity (purity: >99%) and was at a level that could be sold as a by-product in the present invention.

[0154] (Comparative Example 2) The same operations as in Reference Example 1 (Steps 1 to 3 similar to those in Example 1) were carried out on the above sulfuric acid leachate. The volume of the sulfuric acid leachate treated was the same as the volume of the hydrochloric acid leachate treated in Reference Example 1. As a result, 50.2 g of residue was generated by filtration in Step 1. The said residue was mainly composed of calcium sulfate (gypsum) and should be treated as industrial waste. The amount of residue generated during the filtration in Step 2 was as little as 0.1 g in dry weight. In Step 3, 2.64 g of residue was generated by filtration. This residue was mainly composed of calcium sulfate (gypsum) and should be treated as industrial waste.

Explanation of Signs

[0155] 1 Left-end bipolar membrane 1a Left-end anion exchange layer 1b Left-end cation exchange layer 2 Left-side anion exchange membrane 2´ Left-side 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-end anion exchange layer 5b Right-end cation exchange layer 6 Water tank to be treated 7 Acid solution tank 9 Alkali solution tank 10 Bipolar electrodialysis device 11 Anode 12 Cathode 22 Left-side cation exchange membrane 24 Right cation exchange membrane 32 Treated water tank 34 Alkali solution tank< / ph>

Claims

1. A method for producing a raw material solution for lithium compound production by treating acidic water to be treated containing lithium ions, sodium ions, metal ions other than lithium ions and sodium ions, fluoride ions, and chloride ions, comprising: In the treatment of the water to be treated, Step 1 of adding a calcium compound to the water to be treated and making the pH of the water to be treated weakly alkaline to form a solid, and then subjecting the water to be treated containing the solid to solid-liquid separation treatment to obtain treatment liquid A; Step 2 of adding an alkaline substance to treatment liquid A to make the pH of treatment liquid A alkaline to form a solid, and then subjecting treatment liquid A containing the solid to solid-liquid separation treatment to obtain treatment liquid B; Step 3 of adding an oxalate ion source and / or a carbonate ion source to treatment liquid B to form a solid, and then subjecting treatment liquid B containing the solid to solid-liquid separation treatment to obtain treatment liquid C; Step 4 of subjecting treatment liquid C to electrodialysis using an electrodialysis device equipped with a bipolar membrane having an anion exchange layer and a cation exchange layer and a cation exchange membrane, so as to obtain an alkaline liquid containing lithium ions and sodium ions that have permeated through the cation exchange membrane as the raw material solution for lithium compound production. A method for producing a raw material solution for lithium compound production, which implements the above steps.

2. The pH of the water to be treated used in Step 1 is 0.1 to 2.5, In Step 1, the pH of the water to be treated is adjusted to 7.1 to 9.0, In Step 2, the pH of treatment liquid A is adjusted to 9.8 to 13.

0. The method for producing a raw material solution for lithium compound production according to Claim 1.

3. Implement Step 3' of filtering treatment liquid C with a nanofilter and subjecting the obtained filtrate to reverse osmosis membrane treatment to obtain a concentrated liquid, and supplying the concentrated liquid obtained in Step 3' to Step 4. The method for producing a raw material solution for lithium compound production according to Claim 1.

4. The method for producing a raw material liquid for producing a lithium compound according to claim 3, wherein the calcium compound and the alkaline substance are slaked lime, and the nanofilter is formed of poly(piperazine) or polyamide.

5. The method for producing a raw material liquid for producing a lithium compound according to claim 4, wherein the water to be treated supplied to the 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.

6. The method for producing a raw material liquid for producing a lithium compound according to claim 5, wherein the content of lithium ions in the water to be treated supplied to the step 1 is 1000 ppm or more, the content of sodium ions is 100 ppm or less, the content of fluoride ions is 1000 ppm or more, the content of chloride ions is 10000 ppm or more, the content of phosphate ions is 400 ppm or more, the content of iron ions is 5 ppm or more, the content of nickel ions is 300 ppm or more, and the content of aluminum ions is 1500 ppm or more.

7. The method for producing a raw material liquid for producing a lithium compound according to claim 1, wherein the water to be treated is a leachate obtained by leaching a granular material obtained by subjecting waste containing a lithium-ion battery to a granulation treatment including a roasting step, a crushing step, and a magnetic separation step with hydrochloric acid.

8. The method for producing a raw material liquid for producing a lithium compound according to claim 7, wherein the content of lithium ions in the alkaline liquid is 2000 ppm or more, and the content of sodium ions is 800 ppm or less.

9. In the step 3, ammonium carbonate and / or ammonium bicarbonate is used. The alkaline liquid obtained in the step 4 further contains ammonia. Step 5 of further performing evaporation of ammonia from the alkaline solution to obtain an alkaline solution with at least a part of the ammonia removed as a raw material solution for producing the lithium compound. The method for producing a raw material solution for producing a lithium compound according to claim 8.

10. Waste containing a lithium-ion battery is heated at 500 to 1000 °C, then crushed using a crusher to granulate the waste, magnetic separation is performed on the obtained granulated material, the obtained non-magnetized material is immersed in hydrochloric acid to obtain a hydrochloric acid leachate, and the leachate is used as the water to be treated to implement the method for producing a raw material solution for producing a lithium compound according to any one of claims 1 to 9. The method for producing a raw material solution for producing a lithium compound.

11. A method for producing lithium hydroxide powder by crystallizing lithium hydroxide from a raw material solution for producing a lithium compound having a pH of 10 or more, which is produced by the production method according to claim 10.

12. A method for producing lithium hydroxide powder according to claim 11, wherein solid-liquid separation treatment and drying are performed on the lithium-containing water containing the crystallized lithium hydroxide to obtain lithium hydroxide powder.

13. A method for producing lithium carbonate powder by bringing a raw material solution for producing a lithium compound produced by the production method according to claim 10 into contact with carbonic acid.

14. A method for producing lithium carbonate powder according to claim 13, wherein the contact between the raw material solution for producing a lithium compound and carbonic acid is carried out in water to generate solid lithium carbonate, and then solid-liquid separation treatment and drying are performed to obtain lithium carbonate powder.

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