Method for manufacturing lithium hydroxide

Abstract

The present invention relates to a method for manufacturing lithium hydroxide. Particularly, according to an embodiment of the present invention, a method for manufacturing lithium hydroxide may be provided, the method comprising: a solution preparation step in which a lithium hydroxide solution containing impurities and lithium ions is prepared; a bonding acidic solution passage step in which a bonding acidic solution is passed through a chelating resin so that hydrogen ions are bonded to the chelating resin; a distilled water passage step in which, to remove the acidic solution remaining in the chelating resin, distilled water is passed through the chelating resin; a lithium hydroxide passage step in which the lithium hydroxide solution is passed through the chelating resin so that ions included in the impurities are bonded to the chelating resin; and a separating acidic solution passage step in which a separating acidic solution is passed through the chelating resin to which the impurities are bonded, so that the impurities bonded to the chelating resin are separated from the chelating resin.

Description

Method for producing lithium hydroxide

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

[0002] With the growing importance of eco-friendly transportation modes like electric vehicles, demand for lithium secondary batteries, the primary energy storage devices for electric vehicles, is increasing. Lithium is a key component of the cathode material, which determines the battery capacity and voltage of lithium secondary batteries. Because it is difficult to utilize in its pure form, it is processed into compounds for use.

[0003] Lithium compounds used in the manufacture of lithium secondary batteries primarily include lithium carbonate (Li2CO3) and lithium hydroxide (LiOH). Among these, lithium hydroxide is readily synthesized with nickel, which increases the battery capacity of lithium secondary batteries. Therefore, it is primarily used as a cathode material in lithium secondary batteries for electric vehicles, which require high density and capacity. Therefore, the development of technologies for effectively and economically obtaining lithium hydroxide is essential.

[0004] Common methods for obtaining lithium hydroxide include extracting lithium ore mined from a mine, extracting lithium from a salt lake, evaporating the brine to first produce lithium carbonate, and then oxidizing the lithium carbonate to lithium hydroxide, and extracting lithium phosphate from spent lithium-ion batteries containing lithium and then adding a phosphate anion precipitant to produce it.

[0005] However, the conventional method of manufacturing lithium hydroxide leaves various cations, such as calcium and magnesium, remaining in the lithium hydroxide solution. These cations act as impurities during the lithium hydroxide manufacturing process, and the purity of the lithium hydroxide is lowered due to these impurities. To remove these impurities, a method can be used in which a precipitant, such as sodium hydroxide or sodium carbonate, is added to the lithium hydroxide solution, and then cations, such as calcium and magnesium, are precipitated as hydroxides and removed. However, in this case, sodium ions may be mixed into the lithium mixture, lowering the purity of the lithium hydroxide, and there is a limit to controlling the concentration of impurities to an extremely trace level.

[0006] Therefore, there is a need for a method for producing high-purity lithium hydroxide by controlling the concentration of impurities to an extremely trace level without mixing sodium ions.

[0007] The present invention was invented with the above background in mind, and its purpose is to produce high-purity lithium hydroxide by removing cationic impurities from a lithium hydroxide solution containing cationic impurities and lithium ions.

[0008] Additionally, the purpose is to control the concentration of calcium ions among the impurities contained in the lithium hydroxide solution to an extremely trace level.

[0009] According to one embodiment of the present invention, a method for producing lithium hydroxide may be provided, comprising: a solution preparation step of preparing a lithium hydroxide solution containing impurities and lithium ions; and a lithium hydroxide solution passing step of passing the lithium hydroxide solution through a chelating resin, wherein while the lithium hydroxide solution passes through the chelating resin, ions contained in the impurities are exchanged with ions bound to the chelating resin and bound to the chelating resin, and the lithium ions pass through the chelating resin.

[0010] According to one embodiment of the present invention, the impurity is calcium ion (Ca 2+) and a method for producing lithium hydroxide can be provided, wherein the concentration of the calcium ion included in the lithium hydroxide solution in the solution preparation step is 20 ppm or more and 25 ppm or less.

[0011] According to one embodiment of the present invention, a method for producing lithium hydroxide may be provided, wherein the lithium hydroxide solution is provided such that the amount of the lithium hydroxide solution passing through the chelate resin relative to the amount of the chelate resin is 16.7 times or more and 83.3 times or less in volume ratio.

[0012] According to one embodiment of the present invention, a method for producing lithium hydroxide may be provided, which further includes a step of passing an acidic solution for binding through the chelating resin, performed between the solution preparation step and the lithium hydroxide solution passing step, wherein while the lithium hydroxide solution passes through the chelating resin, ions included in the impurities are exchanged with hydrogen ions bound to the chelating resin.

[0013] According to one embodiment of the present invention, a method for producing lithium hydroxide can be provided in which the acid concentration of the acid solution for binding is 60 g / L to 90 g / L.

[0014] According to one embodiment of the present invention, a method for producing lithium hydroxide may be provided, wherein the acidic solution for binding is provided such that the amount of the acidic solution for binding passing through the chelating resin is 4 to 8 times the amount of the chelating resin in a volume ratio.

[0015] According to one embodiment of the present invention, a method for producing lithium hydroxide may be provided, further comprising a distilled water passing step of passing distilled water through the chelating resin, wherein the distilled water passing step is performed between the binding acid solution passing step and the lithium hydroxide solution passing step.

[0016] According to one embodiment of the present invention, a method for producing lithium hydroxide may be provided, wherein the distilled water is provided such that the amount of the distilled water relative to the amount of the chelate resin is 1.5 times or more and 6 times or less in volume ratio.

[0017] According to one embodiment of the present invention, a method for producing lithium hydroxide may be provided, which further includes a step of passing an acidic solution for separation through the chelating resin to which the impurities are bound, performed after the step of passing the lithium hydroxide solution, and wherein while the acidic solution for separation passes through the chelating resin, impurity ions bound to the chelating resin are exchanged with hydrogen ions of the acidic solution for separation.

[0018] According to one embodiment of the present invention, a method for producing lithium hydroxide can be provided in which the acid concentration of the acid solution for separation is 60 g / L to 90 g / L.

[0019] According to one embodiment of the present invention, a method for producing lithium hydroxide may be provided in which the acidic solution for separation is provided such that the amount of the acidic solution for separation passing through the chelate resin is 5 to 6.7 times greater than the amount of the chelate resin in a volume ratio.

[0020] According to the present invention, high-purity lithium hydroxide can be produced by removing cationic impurities from a lithium hydroxide solution containing cationic impurities and lithium ions.

[0021] In addition, the concentration of calcium ions among the impurities contained in the lithium hydroxide solution can be controlled to an extremely trace level.

[0022] Figure 1 is a flowchart sequentially showing a method for manufacturing lithium hydroxide according to one embodiment of the present invention.

[0023] Figure 2 is a graph showing the analysis results according to the ratio of the amount of lithium hydroxide solution to the amount of chelate resin.

[0024] Figure 3 is a graph showing the analysis results according to the ratio of the amount of acid solution for binding to the amount of chelate resin.

[0025] Figure 4 is a graph showing the analysis results according to the ratio of the amount of distilled water to the amount of chelate resin.

[0026] Figure 5 is a graph showing the analysis results according to the ratio of the amount of acid solution for separation to the amount of chelate resin.

[0027] The embodiments of the present invention are provided for the purpose of illustrating the technical concept of the present invention. The scope of the rights according to the present invention is not limited to the embodiments presented below or the specific descriptions of these embodiments.

[0028] Hereinafter, the present invention will be described with reference to the drawings.

[0029] Figure 1 is a flowchart sequentially showing a method for manufacturing lithium hydroxide according to one embodiment of the present invention.

[0030] Referring to FIG. 1, the lithium hydroxide manufacturing method (S1) can manufacture a high-purity lithium hydroxide solution. In the present specification, the lithium hydroxide solution means a solution in which lithium hydroxide (LiOH) is dissolved, and the lithium hydroxide manufacturing method (S1) means that lithium hydroxide is manufactured in the form of an aqueous solution. For example, the lithium hydroxide manufacturing method (S1) may be a series of lithium hydroxide purification methods for removing cationic impurities from a lithium hydroxide solution containing cationic impurities in order to obtain a high-purity lithium hydroxide solution. In this case, the lithium hydroxide manufacturing method (S1) can manufacture a lithium hydroxide solution from which cationic impurities have been removed.

[0031] Solution preparation step (S100)

[0032] The lithium hydroxide manufacturing method (S1) includes a solution preparation step (S100) of preparing a lithium hydroxide solution containing impurities and lithium ions. In the solution preparation step (S100), the lithium hydroxide solution can be prepared by a plurality of methods. For example, the lithium hydroxide solution can be obtained from lithium-containing ores such as spodumene, lepidolite, amblygonite, or petalite. As another example, the lithium hydroxide solution can be obtained by oxidizing lithium carbonate using calcium hydroxide (Ca(OH)2). As another example, the lithium hydroxide solution can be obtained from a spent lithium ion battery after use. The following description focuses on preparing a lithium hydroxide solution from a spent lithium ion battery, but this is merely an example and the present invention is not limited thereto.

[0033] In the solution preparation step (S100), a lithium hydroxide solution can be obtained using lithium carbonate (Li2CO3) extracted from a spent lithium-ion battery. For example, a lithium hydroxide solution can be obtained by adding calcium oxide (CaO) and water to a lithium carbonate cake and reacting the mixture at 70°C to 80°C for 2 to 3 hours (reaction formula 1 below).

[0034] Li2CO3(s) + CaO(s) + H2O = 2LiOH(aq) + CaCO3… (Reaction Formula 1)

[0035] In the solution preparation step (S100), the lithium hydroxide solution contains aluminum ions (Al 3+ ), barium ion (Ba 2+ ), calcium ions (Ca 2+ ), iron ion (Fe 2+ , Fe 3+ ), magnesium ions (Mg 2+ ) and lead ions (Pb 2+) may contain one or more cations as impurities. In particular, according to Reaction Scheme 1, the lithium hydroxide solution may contain a high concentration of calcium ions, and for example, the concentration of calcium ions in the lithium hydroxide solution may be 20 ppm or more and 25 ppm or less. In addition, in the solution preparation step (S100), the lithium hydroxide solution may contain lithium ions, and the concentration of these lithium ions may be 8 g / L or more and 12 g / L or less.

[0036] Lithium hydroxide solution passage step (S200)

[0037] The lithium hydroxide manufacturing method (S1) includes a lithium hydroxide solution passing step (S200) of passing a lithium hydroxide solution through a chelate resin so that ions included in impurities are bound to the chelate resin. For example, the chelate resin may be a styrene-based IDA Porous chelate resin. The chelate resin is one of the cation exchange resins, and the selectivity and adsorption properties of cation exchange resins vary depending on the type of ion. Generally, the selectivity of a cation exchange resin for calcium ions is greater than that of lithium ions. Since the selectivity of the chelate resin for calcium ions is greater than that for lithium ions, while the lithium hydroxide solution is passing through the chelate resin, calcium ions are exchanged with hydrogen ions bound to the chelate resin, and lithium ions included in the lithium hydroxide solution can pass through the chelate resin.

[0038] In the lithium hydroxide solution passing step (S200), the lithium hydroxide solution can be provided to a chelating resin and passed through. While the lithium hydroxide solution passes through the chelating resin, ions contained in impurities are exchanged with hydrogen ions bound to the chelating resin, and lithium ions contained in the lithium hydroxide solution can pass through the chelating resin. In other words, ions contained in the impurities of the lithium hydroxide solution are bound to the chelating resin, and hydrogen ions bound to the chelating resin are separated from the chelating resin. For example, the ions contained in the impurities of the lithium hydroxide solution may be calcium ions, and calcium ions can be exchanged with hydrogen ions bound to the chelating resin. The same applies to other cations other than lithium ions.

[0039] In the lithium hydroxide solution passing step (S200), the lithium hydroxide solution may be provided so that the ratio of the amount of lithium hydroxide solution passing through the chelate resin to the amount of chelate resin is 16.7 to 83.3. That is, the amount of lithium hydroxide solution provided in the lithium hydroxide solution passing step (S200) may have a volume ratio of 16.7 to 83.3 times the amount of chelate resin. For example, if the volume ratio is less than 16.7 times, the amount of lithium hydroxide solution passing through the chelate resin to the amount of chelate resin is excessively small, which is not economical, and if it exceeds 83.3 times, impurities are not sufficiently removed from the lithium hydroxide solution. Meanwhile, in the present specification, in order to distinguish it from the lithium hydroxide solution including impurities in the solution preparation step (S100), the lithium hydroxide solution from which impurities have been removed by the chelate resin is referred to as a lithium hydroxide solution after passing through.

[0040] Acid solution passage step for binding (S300)

[0041] The method for manufacturing lithium hydroxide (S1) is to produce hydrogen ions (H +) may include a binding acid solution passing step (S300) of passing a binding acid solution through a chelating resin so that the binding acid solution is bound to the chelating resin. The binding acid solution passing step (S300) may be performed between the solution preparation step (S100) and the lithium hydroxide solution passing step (S200). In the binding acid solution passing step (S300), while the binding acid solution passes through the chelating resin, ions originally bound to the chelating resin may be exchanged with hydrogen ions of the binding acid solution. For example, ions originally bound to the chelating resin may be exchanged with sodium ions (Na + ), while the acidic solution for binding passes through the chelating resin, the hydrogen ions in the acidic solution for binding may be ion-exchanged with the sodium ions bound to the chelating resin and bound to the chelating resin. However, this is merely an example, and the ions originally bound to the chelating resin may be hydrogen ions. In this case, in the step of passing the acidic solution for binding (S300), while the acidic solution for binding passes through the chelating resin, the acidic solution for binding removes the coating layer on the surface of the chelating resin. In addition, the acidic solution for binding may be one or more solutions of hydrochloric acid (HCl) and sulfuric acid (H2SO4). The acid concentration of the acidic solution for binding may be 60 g / L to 90 g / L.

[0042] In the step of passing the acidic solution for binding (S300), the acidic solution for binding may be provided so that the ratio of the amount of the acidic solution for binding passing through the chelate resin to the amount of the chelate resin is 4 to 8. That is, the amount of the acidic solution for binding provided in the step of passing the acidic solution for binding (S300) may be 4 to 8 times the volume ratio of the amount of the chelate resin. For example, when the volume ratio is less than 4 times, a sufficient amount of hydrogen ions cannot sufficiently bind to the chelate resin, and when the volume ratio exceeds 8 times, the hydrogen ions no longer bind to the chelate resin, which is not economical.

[0043] Distilled water passage step (S400)

[0044] The lithium hydroxide manufacturing method (S1) may include a distilled water passing step (S400) of passing distilled water through a chelate resin to remove the binding acid solution remaining in the chelate resin from the chelate resin after the binding acid solution passing step (S300). The distilled water passing step (S400) may be performed between the binding acid solution passing step (S300) and the lithium hydroxide solution passing step (S200). Here, the binding acid solution remaining in the chelate resin refers to the binding acid solution remaining on the surface of the chelate resin without undergoing ion exchange with the chelate resin while the binding acid solution passes through the chelate resin. For example, if the binding acid solution remaining without binding to the chelate resin is mixed with the lithium hydroxide solution in the lithium hydroxide solution passing step (S200) described above, sulfur (S) or chlorine (Cl) may act as impurities, which may contaminate the process solution in a subsequent process. In this case, by passing distilled water through the chelating resin to wash away the remaining binding acid solution, the inclusion of sulfur or chlorine in the lithium hydroxide solution passing through the chelating resin can be prevented.

[0045] In the distilled water passing step (S400), distilled water may be provided so that the ratio of the amount of distilled water to the amount of chelate resin is 1.5 to 6. That is, the amount of distilled water provided in the distilled water passing step (S400) may be 1.5 to 6 times the volume ratio of the amount of chelate resin. For example, if the volume ratio is less than 1.5 times, the remaining acidic solution for binding is not sufficiently removed, and if the volume ratio exceeds 6 times, the amount of distilled water becomes excessively large, which is not economical.

[0046] Acid solution passage step for separation (S500)

[0047] The lithium hydroxide manufacturing method (S1) may include a separation acid solution passing step (S500) of passing a separation acid solution through a chelate resin to which impurities are bound so that the impurities bound to the chelate resin are separated from the chelate resin. The separation acid solution passing step (S500) may be performed after the lithium hydroxide solution passing step (S200). This is to separate the impurities bound to the chelate resin from the chelate resin in the lithium hydroxide solution passing step (S200) so that the chelate resin can be reused. While the separation acid solution passes through the chelate resin to which impurities are bound, the impurity ions bound to the chelate resin can be exchanged with the hydrogen ions of the separation acid solution. That is, the hydrogen ions of the separation acid solution are bound to the chelate resin, and the calcium ions bound to the chelate resin are separated from the chelate resin. For example, the separation acid solution may be sulfuric acid (H2SO4) or hydrochloric acid (HCl). The acid concentration of the acid solution for separation may be 60 g / L to 90 g / L.

[0048] In the step of passing the acidic solution for separation (S500), the acidic solution for separation may be provided in such a way that the ratio of the amount of the acidic solution for separation passing through the chelate resin to the amount of the chelate resin is 5 to 6.7. That is, the amount of the acidic solution for separation provided in the step of passing the acidic solution for separation (S500) may be 5 to 6.7 times the volume ratio of the amount of the chelate resin. For example, when the volume ratio is less than 5 times, impurity ions are not sufficiently desorbed from the chelate resin, and when it exceeds 6.7 times, the amount of the acidic solution for separation becomes excessively large, which is not economical.

[0049] Hereinafter, an example of a method for producing lithium hydroxide of the present invention will be described.

[0050] Analysis results according to the ratio of lithium hydroxide solution amount to chelate resin amount

[0051] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Amount of lithium hydroxide solution (mL) 1000 2000 3000 4000 5000 6000 7000 Amount of chelate resin (mL) 60 60 60 60 60 60 60 60 Ratio of lithium hydroxide solution to amount of chelate resin 16.7 33.3 50 66.7 8 3.3 100 106.3 Before reaction Lig / L 1 1.2 11.2 11.2 11.2 11.2 11.2 Camg / L 2 2.0 22.0 22.0 22.0 22.0 22.0 22.0 22.0 Reaction Lig / L9.1710.110.110.210.611.111.2 Camg / L1.581.611.671.892.072.222.31 Impurity removal rate Li%19.815.013.412.411.19.408.86 Ca%92.892.792.491.490.689.989.5

[0052] In the above Table 1, Examples 1 to 7 were tested while changing the amount of lithium hydroxide solution under the same experimental conditions. That is, the above Table 1 is tested while changing the ratio of the amount of lithium hydroxide solution passing through the chelate resin to the amount of chelate resin. As can be seen in the above Table 1 and Fig. 2, when the ratio of the amount of lithium hydroxide solution to the amount of chelate resin is 16.7 or more and 83.3 or less (Examples 1 to 5), it can be confirmed that impurities are sufficiently removed, and the removal rate of calcium ions after the reaction is 90.6% to 92.8%. Therefore, when the ratio of the amount of lithium hydroxide solution to the amount of chelate resin is 16.7 or more as in Example 1, the amount of lithium hydroxide solution passing through the chelate resin can be prevented from being excessively reduced. When the ratio of the amount of lithium hydroxide solution to the amount of chelating resin is 83.3 or less as in Example 5, impurities are sufficiently removed from the lithium hydroxide solution (removal rate of 90% or more), resulting in a remarkable effect.

[0053] Analysis results according to the ratio of the amount of acid solution for binding to the amount of chelating resin

[0054] Example 8 Example 9 Example 10 Example 11 Example 12 Amount of sulfuric acid solution (mL) 100 200 300 400 500 Amount of chelate resin (mL) 50 50 50 50 50 Ratio of sulfuric acid solution to chelate resin amount 2 46 8 10 Concentration of sulfuric acid solution after reaction (g / L) 2 1.7 5 2.7 5 9.2 5 9.5 5 9.3

[0055] In the above Table 2, Examples 8 to 12 were tested under the same experimental conditions while changing the amount of the acidic solution for binding. That is, the above Table 2 is tested while changing the ratio of the amount of the acidic solution for binding passing through the chelate resin to the amount of the chelate resin. In this example, a sulfuric acid solution having a concentration of 60 g / L was used as the acidic solution for binding. As can be seen in the above Table 2 and Fig. 3, when the ratio of the amount of the sulfuric acid solution to the amount of the chelate resin is 4 or more and 8 or less (Examples 9 to 11), it can be confirmed that the sulfuric acid solution reacts sufficiently and the concentration of the sulfuric acid solution after the reaction becomes 52.7 g / L to 59.5 g / L. Therefore, when the ratio of the amount of the sulfuric acid solution to the amount of the chelate resin is 4 or more as in Example 9, it has a remarkable effect on the hydrogen ion binding rate. When the ratio of the amount of sulfuric acid solution to the amount of chelating resin is 8 or less as in Example 11, it is possible to prevent the amount of sulfuric acid solution added from becoming excessively large while maintaining the hydrogen ion bonding rate at a predetermined level.

[0056] Analysis results according to the ratio of distilled water volume to chelate resin volume

[0057] Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 Amount of distilled water (mL) 25 50 75 100 200 300 400 500 Amount of chelate resin (mL) 50 50 50 50 50 50 50 Ratio of distilled water to the amount of chelate resin 0.5 1.0 1.5 24 6 8 10 Concentration of sulfuric acid solution after reaction (g / L) 52.1 27.4 17.7 13.4 0.08 0.07 0.05 0.04

[0058] In the above Table 3, Examples 13 to 20 were tested under the same experimental conditions while changing the amount of distilled water. That is, the above Table 3 is tested while changing the ratio of the amount of distilled water passing through the chelate resin to the amount of chelate resin. As can be seen in the above Table 3 and Fig. 4, when the ratio of the amount of distilled water to the amount of chelate resin is 1.5 or more and 6 or less (Examples 15 to 18), it can be confirmed that the sulfuric acid solution is sufficiently removed, so that the concentration of the sulfuric acid solution after the reaction becomes 17.7 g / L to 0.07 g / L. Therefore, when the ratio of the amount of distilled water to the amount of chelate resin is 1.5 or more, as in Example 15, it has a remarkable effect on the removal of the remaining acidic solution for binding. When the ratio of the amount of distilled water to the amount of chelate resin is 6 or less, as in Example 18, the removal rate of the remaining acidic solution for binding can be maintained at a predetermined level while preventing the amount of distilled water introduced from becoming excessively large.

[0059] Analysis results according to the ratio of the amount of acid solution for separation to the amount of chelating resin

[0060] Example 21 Example 22 Example 23 Example 24 Example 25 Amount of sulfuric acid solution (mL) 100 200 300 400 500 Amount of chelate resin (mL) 60 60 60 60 60 Ratio of acid solution for separation to amount of chelate resin 1.6 3.3 56.7 8.3 Concentration of calcium ions in chelate resin before reaction (mg / L) 2,63 31,85 0 59 73 14 30 6 Concentration of calcium ions in chelate resin after reaction (mg / L) 46 8 75 6 17 0 9.7 13.42 Cumulative recovery rate of calcium ions (%) 29.6 77.4 88.2 88.8 89.1

[0061] In the above Table 4, Examples 21 to 25 were tested under the same experimental conditions while changing the amount of the acidic solution for separation. That is, the above Table 4 is tested while changing the ratio of the amount of the acidic solution for separation passing through the chelate resin to the amount of the chelate resin. In this example, a sulfuric acid solution having a concentration of 90 g / L was used as the acidic solution for separation. As can be seen in the above Table 4 and Fig. 5, when the ratio of the amount of the sulfuric acid solution to the amount of the chelate resin is 5 or more and 6.7 or less (Examples 23 to 24), it can be confirmed that calcium ions are sufficiently desorbed from the chelate resin, and the cumulative recovery rate of calcium ions is 88.2% to 88.8%. Therefore, when the ratio of the amount of the acidic solution for separation to the amount of the chelate resin is 5 or more as in Example 23, impurities are sufficiently desorbed from the chelate resin, resulting in a remarkable effect. When the ratio of the amount of acid solution for separation to the amount of chelate resin is 6.7 or less as in Example 24, the amount of sulfuric acid solution introduced can be prevented from becoming excessively large while maintaining the desorption rate of impurities at a predetermined level.

[0062] Although the embodiments of the present invention have been described with reference to the attached drawings, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical idea or essential features thereof.

[0063] Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims rather than the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims

1. Solution preparation step for preparing a lithium hydroxide solution containing impurities and lithium ions; and Comprising a lithium hydroxide solution passing step of passing the lithium hydroxide solution through a chelating resin, While the lithium hydroxide solution passes through the chelating resin, the ions contained in the impurities are exchanged with the ions bound to the chelating resin and bound to the chelating resin, and the lithium ions pass through the chelating resin. Method for producing lithium hydroxide.

2. In paragraph 1, The above impurity is calcium ion (Ca 2+ ) including, In the above solution preparation step, the concentration of the calcium ion contained in the lithium hydroxide solution is 20 ppm or more and 25 ppm or less. Method for producing lithium hydroxide.

3. In paragraph 1, The lithium hydroxide solution is provided so that the amount of the lithium hydroxide solution passing through the chelate resin is 16.7 times or more and 83.3 times or less in volume ratio to the amount of the chelate resin. Method for producing lithium hydroxide.

4. In paragraph 1, It is performed between the above solution preparation step and the lithium hydroxide solution passing step, and further includes a binding acid solution passing step of passing the binding acid solution through the chelating resin. While the lithium hydroxide solution passes through the chelating resin, the ions contained in the impurities are exchanged with the hydrogen ions bound to the chelating resin. Method for producing lithium hydroxide.

5. In paragraph 4, The acid concentration of the above-mentioned acid solution for binding is 60 g / L to 90 g / L. Method for producing lithium hydroxide.

6. In paragraph 4, The above-mentioned acidic solution for binding is provided so that the amount of the acidic solution for binding passing through the chelating resin is 4 to 8 times the amount of the chelating resin by volume ratio. Method for producing lithium hydroxide.

7. In paragraph 4, Further comprising a distilled water passing step of passing distilled water through the above chelating resin, The above distilled water passing step is performed between the above binding acid solution passing step and the lithium hydroxide solution passing step. Method for producing lithium hydroxide.

8. In paragraph 7, The distilled water is provided so that the amount of the distilled water is 1.5 to 6 times the amount of the chelate resin in volume ratio. Method for producing lithium hydroxide.

9. In paragraph 1, It is performed after the lithium hydroxide solution passing step, and further includes a separation acid solution passing step of passing the separation acid solution through the chelating resin to which the impurities are bound. While the acidic solution for separation passes through the chelating resin, the impurity ions bound to the chelating resin are exchanged with the hydrogen ions of the acidic solution for separation. Method for producing lithium hydroxide.

10. In paragraph 9, The acid concentration of the acid solution for separation is 60 g / L to 90 g / L. Method for producing lithium hydroxide.

11. In paragraph 9, The above separation acid solution is provided so that the amount of the separation acid solution passing through the chelate resin is 5 to 6.7 times the amount of the chelate resin in volume ratio. Method for producing lithium hydroxide.

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