Method for producing lithium-containing solution and method for producing lithium hydroxide

Abstract

To provide a method for producing a lithium-containing solution and a method for producing lithium hydroxide, which can enhance the purity of the resulting lithium compound.SOLUTION: A method for producing a lithium-containing solution comprises an ion exchange step in which an ion-exchange resin is used to obtain a lithium-containing solution in which predetermined metal elements are less than a pre-treatment lithium-containing solution. In the ion exchange step, the pre-treatment lithium-containing solution is passed through a column containing the ion exchange resin to remove the predetermined metal elements. A predetermined amount of the pre-treatment lithium-containing solution in the pre-treatment lithium-containing solution after starting to pass the column is not included in the lithium-containing solution. This enables the removal of metal elements to be removed in the initial stage of the passage of the solution while suppressing the amount of waste of the pre-treatment lithium-containing solution, thereby reducing the content of metal to be removed in the lithium-containing solution.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing a lithium-containing solution and a method for producing lithium hydroxide. More specifically, the present invention relates to a method for producing a lithium-containing solution and a method for producing lithium hydroxide, which can increase the purity of the finally obtained lithium compound.

Background Art

[0002] In recent years, the demand for NCA, which is a nickel-based cathode material, has been expanding as a cathode material for in-vehicle batteries. And when the nickel-based cathode material Material is used in an in-vehicle battery, it is economically preferable that lithium, which is one of its constituent elements, be supplied as lithium hydroxide. Patent Document 1 discloses a method for producing lithium hydroxide capable of obtaining a lithium hydroxide-containing solution in which lithium hydroxide is dissolved from a predetermined lithium-containing solution obtained from salt lake brine or the like. By this method, it is possible to obtain lithium hydroxide with low cost and high purity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, an impurity removal step is provided before the conversion step. In this impurity removal step, some metal ions are removed from the second lithium-containing solution, and the purity of the final product, lithium hydroxide, is increased. In Patent Document 1, there is a disclosure that this impurity removal step includes, for example, a neutralization step and an ion exchange step, or an oxidation step, a neutralization step, and an ion exchange step.

[0005] However, for the positive electrode material for in - vehicle batteries, it may be necessary to further increase the purity of lithium hydroxide. In this case, in the lithium hydroxide produced by the production method of Patent Document 1, there is a problem that a part of metal ions remains, so that the purity of the finally obtained lithium hydroxide cannot be increased to a predetermined purity.

[0006] In view of the above circumstances, an object of the present invention is to provide a method for producing a lithium - containing solution and a method for producing lithium hydroxide that can increase the purity of the finally obtained lithium compound.

Means for Solving the Problems

[0007] The method for producing a lithium - containing solution of the first invention includes: A neutralization step of adding an alkali to a crude lithium-containing solution to obtain a lithium-containing solution before treatment; an ion - exchange step of contacting an ion - exchange resin with a lithium - containing solution before treatment to obtain a lithium - containing solution in which a predetermined metal element is less than that in the lithium - containing solution before treatment. In the ion - exchange step, the lithium - containing solution before treatment is passed through a column in which the ion - exchange resin is incorporated to remove a predetermined metal element, and a predetermined amount of the lithium - containing solution before treatment after starting to pass through the column is not included in the lithium - containing solution. The method for producing a lithium - containing solution of the second invention is characterized in that, in the first invention, the ion - exchange resin is an iminodiacetic acid - type chelating resin, and the functional group of the iminodiacetic acid - type chelating resin is in the sodium form. The method for producing a lithium - containing solution of the third invention is characterized in that, in the first invention or the second invention, the predetermined amount is less than BV4. The method for producing a lithium - containing solution of the fourth invention is characterized in that, in any one of the first invention to the third invention, the pH of the lithium - containing solution before treatment is 7 or more and 11 or less. The method for producing lithium hydroxide according to the fifth invention is a method for producing lithium hydroxide using a lithium-containing solution produced by the method for producing a lithium-containing solution according to any one of the first to fourth inventions, and the method for producing lithium hydroxide includes a lithium hydroxide-containing solution From solids lithium hydroxide To obtain a crystallization step and a washing step of washing the Solid lithium hydroxide with a washing liquid, and is characterized in that the washing liquid is a lithium hydroxide-containing solution having a solubility equal to or higher than a predetermined solubility. The method for producing lithium hydroxide according to the sixth invention is characterized in that, in the fifth invention, the washing liquid is a saturated lithium hydroxide solution.

Advantages of the Invention

[0008] According to the first invention, by not including a predetermined amount of the pre-treatment lithium-containing solution in the lithium-containing solution from the start of liquid passing through the column in the ion exchange step, while suppressing the amount of waste of the pre-treatment lithium-containing solution, metal elements to be removed contained in the initial stage of liquid passing can be removed, and the content of the metal to be removed in the lithium-containing solution can be reduced. According to the second invention, since the ion exchange resin is an iminodiacetic acid type chelating resin and the functional group of the iminodiacetic acid type chelating resin is in the sodium form, the properties of the solution in the ion exchange step are stabilized, and the certainty of removing metal elements to be removed is improved. According to the third invention, since a predetermined amount of the initial stage of liquid passing is smaller than BV4, the amount of waste of the lithium-containing solution can be further suppressed, and the acquisition rate of a high-purity lithium-containing solution can be increased. According to the fourth invention, since the pH of the pre-treatment lithium-containing solution is 7 or more and 11 or less, calcium among the metal elements to be removed can be removed more reliably. According to the fifth invention, in the washing step after the crystallization step, by using a lithium hydroxide-containing solution having a solubility equal to or higher than a predetermined solubility, it is possible to suppress the obtained crystals from dissolving again, and the crystals of lithium hydroxide can be obtained without waste. According to the sixth invention, since the cleaning liquid is a saturated lithium hydroxide solution, the crystallized crystals will no longer dissolve again, and lithium hydroxide crystals can be obtained more efficiently without waste.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] Next, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below are examples of a method for producing a lithium-containing solution or a method for producing lithium hydroxide for embodying the technical idea of the present invention, and the present invention is not limited to the following methods for producing a lithium-containing solution and a method for producing lithium hydroxide.

[0011] The method for producing a lithium-containing solution according to the present invention includes an ion exchange step of contacting a lithium-containing solution before treatment with an ion exchange resin to obtain a lithium-containing solution in which a predetermined metal element is less than that in the lithium-containing solution before treatment. In the ion exchange step, the lithium-containing solution before treatment is passed through a column containing the ion exchange resin to remove a predetermined metal element. And among the lithium-containing solution before treatment, a predetermined amount of the lithium-containing solution before treatment is not included in the lithium-containing solution after starting to pass through the column.

[0012] By not including a predetermined amount of the pre-treatment lithium-containing solution in the lithium-containing solution from the start of liquid flow through the column in the ion exchange step, it is possible to remove the metal elements to be removed, which are included in the initial liquid flow, while suppressing the amount of the pre-treatment lithium-containing solution to be discarded, and to reduce the content of the metal to be removed in the lithium-containing solution.

[0013] Further, in the method for producing a lithium-containing solution, it is preferable that the ion exchange resin is an iminodiacetic acid type chelating resin and the functional group of the iminodiacetic acid type chelating resin is in the sodium form. Thereby, the properties of the solution in the ion exchange step are stabilized, and the certainty of removing the metal elements to be removed is improved.

[0014] Also, the predetermined amount is preferably 4 BV or less. Thereby, the amount of the lithium-containing solution to be discarded can be further suppressed, and the acquisition rate of the high-purity lithium-containing solution can be increased.

[0015] Also, the pH of the pre-treatment lithium-containing solution is preferably 7 or more and 11 or less. Calcium among the metal elements to be removed can be removed more reliably.

[0016] Further, the method for producing lithium hydroxide according to the present invention is a method for producing lithium hydroxide using a lithium-containing solution produced by the method for producing a lithium-containing solution according to any one of the above, and the method for producing the lithium hydroxide includes a crystallization step of obtaining solid lithium hydroxide from a lithium hydroxide-containing solution and a washing step of washing the solid lithium hydroxide with a washing liquid, and the washing liquid is a lithium hydroxide solution having a solubility equal to or higher than a predetermined solubility. Containing It is preferably a solution. Thereby, it is possible to suppress the obtained crystals from dissolving again, and it is possible to obtain the crystals of lithium hydroxide without waste.

[0017] Further, it is preferable that the cleaning liquid is a saturated lithium hydroxide solution. This prevents the crystallized crystals from dissolving again, and enables the crystals of lithium hydroxide to be obtained more efficiently without waste.

[0018] (Method for producing a lithium-containing solution, including an embodiment of the method for producing a lithium-containing solution) FIG. 1 shows a flowchart of a method for producing a lithium hydroxide-containing solution, including a method for producing a lithium-containing solution according to an embodiment of the present invention. The steps provided before and after the method for producing the lithium-containing solution of the present embodiment are not particularly limited. However, for example, by providing the steps as shown below before and after, it is possible to obtain a lithium hydroxide-containing solution with high purity. 。 < Neutralization step FIG. 1 shows a flowchart of a method for producing a lithium hydroxide-containing solution, including a method for producing a lithium-containing solution according to an embodiment of the present invention. The neutralization step shown in FIG. 1 is preferably provided upstream of the method for producing the lithium-containing solution according to the present embodiment. This neutralization step is a step of adding an alkali to a crude lithium-containing solution to obtain a pre-treatment lithium-containing solution which is a neutralized solution. By this step, for example, a neutralized precipitate containing impurities other than lithium chloride is obtained. Here, the crude lithium-containing solution refers to a solution containing a lithium compound when this liquid is crystallized. For example, a solution obtained by reacting lithium carbonate with hydrochloric acid, a solution obtained by extracting from a lithium-containing ore with hydrochloric acid, or Tube a solution obtained by selectively adsorbing and separating lithium from water corresponds thereto. Note that this crude lithium-containing solution is Tube preferably a solution obtained by selectively adsorbing and separating lithium from water.

[0019] In the neutralization process, an alkali is added to remove metals other than lithium. Ion exchange resins are mainly used to remove metal ions with a valence of two or more. However, if the liquid before contacting the ion exchange resin contains a very large amount of metal ions with a valence of two or more, it is necessary to frequently replace the ion exchange resin. However, since ion exchange resins are expensive, the cost of manufacturing lithium hydroxide increases, or the workload of replacing the ion exchange resin increases. Also, the workload of regenerating the ion exchange resin increases. Therefore, in the neutralization process, an alkali is added to remove a part of the metals other than lithium. Examples of metals other than lithium include divalent magnesium and manganese. Specifically, in the neutralization process, for example, sodium hydroxide is added to a lithium chloride-containing solution, which is a crude lithium-containing solution, to precipitate magnesium and manganese as magnesium hydroxide and manganese hydroxide, and the precipitate is recovered to remove metals other than lithium. To precipitate and remove magnesium or the like, any alkaline substance may be used, but if the pH is too high, the cost of the neutralizing agent increases, which is not preferable. Therefore, the pH of the neutralized solution after the neutralization process is preferably 8.5 or more and 12 or less.

[0020] Note that although the neutralization process has been described as a process constituting the method for producing a lithium hydroxide-containing solution, the pre-treatment lithium-containing solution in the method for producing a lithium-containing solution of the present invention does not necessarily have to be a pre-treatment lithium-containing solution obtained through the neutralization process. Further, a pre-treatment lithium-containing solution obtained including processes other than the neutralization process can be used without any problem.

[0021] <Ion Exchange Process> The method for producing a lithium-containing solution according to an embodiment of the present invention includes an ion exchange step. FIG. 1 shows an example of the positioning of the ion exchange step in the method for producing a lithium hydroxide-containing solution. This ion exchange step is a step of bringing a lithium-containing solution before treatment into contact with an ion exchange resin to obtain a lithium-containing solution. In the ion exchange step, all or part of calcium, aluminum, manganese, and magnesium, which are predetermined metal elements, are removed. Compared with the lithium-containing solution before treatment, some or all of these metal elements contained in the lithium-containing solution are reduced.

[0022] Here, the "lithium-containing solution before treatment" is used as a term meaning the solution until the ion exchange step is completed. That is, the "lithium-containing solution before treatment" includes both the solution in the stage before being contacted with the ion exchange resin and the solution in the stage of being contacted with the ion exchange resin.

[0023] The ion exchange resin is a kind of synthetic resin and has a structure that ionizes as an ion exchange group in a part of its molecular structure. In the ion exchange step, an ion exchange resin capable of removing divalent or higher metal ions, that is, an iminodiacetic acid type chelate resin or an iminodiacetate type chelate resin, is preferable. The pH of the solution after neutralization in the ion exchange step is determined by the ion exchange resin to be a preferable value. However, it is preferable that the ion exchange step is directly performed on the lithium-containing solution before treatment obtained in the neutralization step.

[0024] Furthermore, among the iminodiacetic acid type chelate resin and the iminodiacetate type chelate resin, it is preferable that the functional group is in the sodium form.

[0025] When the ion exchange resin is an iminodiacetic acid type chelate resin and the functional group of the iminodiacetic acid type chelate resin is in the sodium form, the properties of the solution in the ion exchange step are stabilized, and the certainty of removing the metal elements to be removed is improved.

[0026] In this embodiment, the method of contacting the ion exchange resin with the lithium-containing solution before treatment is a method using a column. The flow rate of the lithium-containing solution before treatment passing through this column is preferably not less than SV1 and not more than SV7. SV is the abbreviation of Space Velocity, which represents the flow rate per unit time (1 hour) (the unit is BV as described below). If the flow rate is less than SV1, the efficiency of lithium hydroxide production deteriorates. Also, if the flow rate is greater than SV7, the liquid flow becomes too fast and metal capture may not be possible. By having this flow rate, divalent metals such as magnesium and calcium can be more reliably removed.

[0027] Also, the flow rate of the solution after neutralization passing through the column is preferably not less than BV10 and not more than BV35. BV is the abbreviation of Bed Volume, which is a unit representing how many times the volume of the ion exchange resin in the column. If the flow rate is less than BV10, the efficiency of lithium hydroxide production deteriorates. Also, if the flow rate is greater than BV35, breakthrough beyond the metal capture capacity of the ion exchange resin may occur and metal capture may not be possible. By having this flow rate, magnesium and calcium can be removed even more reliably.

[0028] Note that the ion exchange resin used in the ion exchange step is renewable. By immersing the used ion exchange resin in a liquid with a hydrogen concentration of the acid of not less than 0.3 mol / L and not more than 2.0 mol / L, the captured metal elutes.

[0029] In the ion exchange step of this embodiment, among the lithium-containing solution before treatment, a predetermined amount of the lithium-containing solution before treatment is extracted after starting to flow through the column, and this extracted lithium-containing solution before treatment is not included in the lithium-containing solution obtained after the ion exchange step.

[0030] For example, when an iminodiacetic acid type chelating resin with a sodium-type functional group is used as the ion exchange resin, at the initial stage of starting the ion exchange process, sodium mixes into the lithium-containing solution before treatment, and there is a problem that the sodium remains in the lithium-containing solution obtained after the ion exchange process. Metals other than lithium remaining in the lithium-containing solution become impurities in the final lithium compound. For example, when this lithium compound is used as a material for the positive electrode of a secondary battery, problems such as a shortened life of the secondary battery occur. Therefore, in order to remove impurities mixed in at the initial stage of the ion exchange process, a predetermined amount of the lithium-containing solution before treatment is withdrawn after starting to pass the solution through the column, and then the withdrawn lithium-containing solution before treatment is not included in the lithium-containing solution obtained after the ion exchange process. For example, when the lithium-containing solution before treatment is repeatedly passed through the column, the lithium-containing solution before treatment in the initial stage is withdrawn, and other lithium-containing solutions before treatment are repeatedly passed through.

[0031] By not including a predetermined amount of the lithium-containing solution before treatment, which is determined in advance from the start of passing the solution through the column in the ion exchange process, in the lithium-containing solution obtained after the ion exchange process, it is possible to remove the metal elements to be removed, which are included in the initial-stage passing of the solution, while suppressing the amount of waste of the lithium-containing solution before treatment, and it is possible to reduce the content of the metal to be removed in the lithium-containing solution.

[0032] In this embodiment, a predetermined amount of the lithium-containing solution before treatment is withdrawn after starting to pass the solution through the column. It is preferable that this predetermined amount to be withdrawn is smaller than BV4. Thereby, it is possible to suppress the amount of waste of the lithium-containing solution and increase the acquisition rate of a high-purity lithium-containing solution.

[0033] In addition, in this embodiment, it is preferable that the pH of the lithium-containing solution before treatment is 7 or more and 11 or less. Among ion exchange resins, chelating resins have a pH dependence in which the adsorption efficiency increases as the pH increases. Therefore, when the pH is less than 7, calcium cannot be adsorbed and removed. When the pH is greater than 11, the adsorption amount of co-adsorbed Li increases. That is, the loss of Li increases. Furthermore, the amount of neutralizing agent such as NaOH used increases, resulting in an increase in cost. By having the pH of the lithium-containing solution before treatment be 7 or more and 11 or less, calcium among the metal elements to be removed can be more reliably removed.

[0034] <Conversion step> As shown in FIG. 1, the lithium-containing solution obtained by the method for producing a lithium-containing solution according to this embodiment is, for example, in the conversion step, a lithium compound such as lithium chloride contained in the lithium-containing solution is converted to lithium hydroxide to obtain a lithium hydroxide-containing solution in which lithium hydroxide is dissolved. In the following description, it will be described on the assumption that the lithium compound contained in the lithium-containing solution is lithium chloride.

[0035] When the lithium compound in the lithium-containing solution is lithium chloride, lithium chloride is dissolved in the lithium-containing solution. In this step, for example, by electrodialysis using a bipolar membrane, these liquids are converted into a lithium hydroxide-containing solution containing lithium hydroxide and hydrochloric acid. That is, by performing electrodialysis, lithium chloride in the lithium-containing solution is decomposed, and the lithium ions of lithium chloride pass through the cation exchange membrane and combine with hydroxide ions to become lithium hydroxide. For example, chloride ions pass through the anion exchange membrane and become hydrochloric acid. The recovered hydrochloric acid can be recycled to the elution step. This can reduce the amount of hydrochloric acid used.

[0036] In addition to electrodialysis using a bipolar membrane, electrodialysis using, for example, an ion exchange membrane corresponds to the conversion step. When a cation exchange membrane is used as the ion exchange membrane, lithium hydroxide is generated in the cathode chamber.

[0037] (Method for producing lithium hydroxide according to an embodiment of the present invention) FIG. 2 shows a flowchart of a method for producing lithium hydroxide according to an embodiment of the present invention. As shown in FIG. 2, the method for producing lithium hydroxide described below has a configuration in which a crystallization step and a washing step are added to the lithium hydroxide-containing solution produced by the method for producing a lithium hydroxide-containing solution shown in FIG. 1. Since the steps for obtaining the lithium hydroxide-containing solution are the same as those of the production method shown in FIG. 1, the description thereof is omitted.

[0038] <Crystallization step> In the crystallization step, solid lithium hydroxide is obtained by solidifying the lithium hydroxide dissolved in the lithium hydroxide-containing liquid. Together with this solid lithium hydroxide, a crystallization mother liquor is obtained. In the conversion step, lithium becomes lithium hydroxide, and alkali metals such as sodium and potassium also become hydroxides. Therefore, these are also contained in the lithium hydroxide-containing liquid obtained in the conversion step. Further, when the lithium compound contained in the lithium-containing solution is lithium chloride, the chloride ion as an anion also passes through the membrane and is contained in the lithium hydroxide-containing liquid. In the crystallization step, the difference in solubility of each hydroxide is utilized to solidify lithium hydroxide and separate the contained impurities.

[0039] In the crystallization step, the lithium hydroxide-containing liquid is heated and concentrated. At this time, the concentration of metal ions contained in the liquid increases, and lithium hydroxide, which has a relatively low solubility initially, precipitates and solidifies first. The precipitated lithium hydroxide is recovered as solid lithium hydroxide. At this time, sodium hydroxide and potassium hydroxide, which have relatively high solubility, remain in the liquid without precipitation. As a result, the purity of the recovered lithium hydroxide increases.

[0040] For example, at 60°C, the solubility of lithium hydroxide is 13.2 g / 100 g of water. Compared with 174 g / 100 g of water for sodium hydroxide and 154 g / 100 g of water for potassium hydroxide, it can be seen that the solubility of lithium hydroxide is extremely low. Since the chloride ions are also 2 g / L even when performing the heating and concentration operation, they do not precipitate in lithium hydroxide as an alkali metal chloride.

[0041] The crystallization step can be industrially carried out by continuous crystallization using a crystallization tank. It can also be carried out by batch crystallization. The crystallization mother liquor generated in the crystallization step is a concentrated alkali solution. Since this crystallization mother liquor contains lithium hydroxide corresponding to the solubility, by repeating it in the steps before the neutralization step, the recovery rate of lithium can be increased. In addition, the cost of the neutralizing agent can be reduced.

[0042] <Washing Step> When recovering the solid lithium hydroxide obtained in the crystallization step, the crystallization mother liquor may adhere to the solid lithium hydroxide. As shown in Figure 2, in this embodiment, the solid lithium hydroxide (before the washing step) obtained in the crystallization step is washed with a washing liquid to wash away the crystallization mother liquor adhering to the solid lithium hydroxide (before the washing step), thereby obtaining solid lithium hydroxide (after the washing step).

[0043] In this embodiment, the washing liquid used in the washing step is a lithium hydroxide-containing solution having a solubility equal to or higher than a predetermined solubility. For example, since the solubility of lithium hydroxide at 0°C is 12 g / 100 g of water, a lithium hydroxide-containing solution with a solubility lower than that, such as 10 g / 100 -hydrate of solubility, is preferred. Furthermore, the washing liquid is preferably a saturated lithium hydroxide solution.

[0044] In the washing step after the crystallization step, by using a lithium hydroxide-containing solution having a solubility equal to or higher than a predetermined solubility, it is possible to suppress the redissolution of the obtained crystals, and the lithium hydroxide crystals can be obtained without waste.

[0045] Since the cleaning liquid is a saturated lithium hydroxide solution, the crystallized crystals will not dissolve again, and lithium hydroxide crystals can be obtained more efficiently without waste.

[0046] (Others) In the method for producing lithium hydroxide according to the present invention, although it has been described that the lithium hydroxide-containing solution obtained by the method for producing a lithium hydroxide-containing solution shown in FIG. 1 is used, it is not particularly limited thereto. Any solution containing lithium hydroxide can be used in the method for producing lithium hydroxide according to the present invention.

Example

[0047] Specific examples of the method for producing a lithium-containing solution according to the present invention will be described below, but the present invention is not limited to these examples.

[0048] (Example 1) <Before the ion exchange step> As the lithium-containing solution before treatment, a lithium chloride-containing solution having the composition shown in Table 1 was prepared through a neutralization step or the like.

[0049]

Table 1

[0050] <Ion exchange step> A column equipped with an ion exchange resin was prepared. The ion exchange resin was an iminodiacetic acid type ion exchange resin, and a resin with a sodium-type functional group (Amberlite IRC743) was used. The lithium-containing solution before treatment adjusted to a pH of 8.2 was passed through this column at an SV (Space Velocity) of 5 and a BV (Bed Volume) of 30. At that time, a part of the lithium-containing solution before treatment was extracted every BV1, and the liquid-phase concentrations of lithium and sodium for each BV1 were measured. The measurement results are shown in FIG. 3. Also, the composition of the entire lithium-containing solution from BV4 to BV30 recovered after extracting the lithium-containing solution before treatment by BV3 at the start of the liquid passing is shown in Table 2.

[0051]

Table 2

[0052] As shown in Fig. 3, it can be seen that the concentration of sodium in the liquid is high between BV1 and BV3. It can be inferred that this is because the sodium of the functional group of the chelating resin has eluted. And in this example, the lithium-containing solution before the treatment up to BV3 was extracted, and the composition of the lithium-containing solution from BV4 to BV30 was measured. It can be seen that by passing through the ion exchange step, the concentration of Ca, which is a divalent metal element, in the liquid decreased, while the increase in the concentration of Na could be suppressed. In Fig. 3, Li is less at BV1 and BV2, which can be inferred to be because the liquid in the column gap was extruded or the chelating resin took in Li instead of Na.

[0053] <The latter stage of the ion exchange step> Using the lithium-containing solution obtained in the ion exchange step, a conversion step was carried out to obtain a lithium hydroxide-containing solution with less impurities.

[0054] (Comparative Example 1) The lithium-containing solution before treatment was passed through the column, and a lithium-containing solution was obtained without extracting the lithium-containing solution before treatment in particular. Other conditions were the same as in Example 1. Table 3 shows the results of measuring the concentration of metals in the liquid of the entire lithium-containing solution in this case.

[0055]

Table 3

[0056] The decrease in the concentration of Ca in the liquid by the ion exchange step is the same as in Example 1, but it can be seen that the concentration of Na increased because the initial liquid passing was not excluded.

Claims

1. Adding an alkali to a crude lithium-containing solution to obtain a pre-treatment lithium-containing solution in a neutralization step, and contacting the pre-treatment lithium-containing solution with an ion exchange resin to obtain a lithium-containing solution in which a predetermined metal element is less than that in the pre-treatment lithium-containing solution, in an ion exchange step, In the ion exchange step, the pre-treatment lithium-containing solution is passed through a column containing the ion exchange resin to remove a predetermined metal element, Among the pre-treatment lithium-containing solution, a predetermined amount of the pre-treatment lithium-containing solution starting from the time when it starts to be passed through the column is not included in the lithium-containing solution, A method for producing a lithium-containing solution, characterized in that.

2. The ion exchange resin is an iminodiacetic acid type chelating resin, The functional group of the iminodiacetic acid type chelating resin is in the sodium form, The method for producing a lithium-containing solution according to claim 1, characterized in that.

3. The predetermined amount is less than BV4, The method for producing a lithium-containing solution according to claim 1 or 2, characterized in that.

4. The pH of the pre-treatment lithium-containing solution is 7 or more and 11 or less, The method for producing a lithium-containing solution according to any one of claims 1 to 3, characterized in that.

5. A method for producing lithium hydroxide using a lithium-containing solution produced by the method for producing a lithium-containing solution according to any one of claims 1 to 4, The method for producing lithium hydroxide includes a crystallization step of obtaining solid lithium hydroxide from a lithium hydroxide-containing solution, and A washing step of washing the solid lithium hydroxide with a washing liquid, Including, The washing liquid is a lithium hydroxide-containing solution having a solubility equal to or higher than a predetermined solubility, A method for producing lithium hydroxide, characterized in that.

6. The washing liquid is a saturated lithium hydroxide solution, The method for producing lithium hydroxide according to claim 5, characterized in that.

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