Lithium hydroxide manufacturing method

Abstract

The present invention relates to a method for producing lithium hydroxide. Specifically, according to one embodiment of the present invention, there may be provided a method for producing lithium hydroxide, including: a solution preparing step of preparing a lithium hydroxide solution containing impurities and lithium ions; a binding acidic solution passing step of passing a binding acidic solution through a chelating resin so that hydrogen ions are bound to the chelating resin; a distilled water passing step of passing distilled water through the chelating resin to remove the binding acidic solution remaining on the chelating resin; a lithium hydroxide passing step of passing a lithium hydroxide solution through the chelating resin so that ions contained in the impurities are bound to the chelating resin; and a separating acidic solution passing step of passing a separating acidic solution through the chelating resin to which the impurities have been bound so that the impurities bound to the chelating resin are separated from the chelating resin.

Description

[Technical Field]

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

[0002] Recently, as the importance of environmentally friendly transportation methods such as electric vehicles has grown, the demand for lithium secondary batteries, which are used as the main energy storage devices for electric vehicles, has increased. Lithium is a core material for the cathode that determines the battery capacity and voltage of lithium secondary batteries, and since it is difficult to use in its pure form, it is processed into a compound.

[0003] The lithium compounds used in the manufacture of lithium secondary batteries are broadly divided into lithium carbonate (Li2CO3) and lithium hydroxide (LiOH). Of these, lithium hydroxide is easy to synthesize with nickel, which increases the battery capacity of lithium secondary batteries, and is therefore mainly used as a cathode material for lithium secondary batteries for electric vehicles, which require high density and capacity. Therefore, there is a need to develop a technology to obtain lithium hydroxide effectively and economically.

[0004] Generally, lithium hydroxide can be obtained by extracting it from lithium ore mined in mines, by extracting it from a salt lake and then evaporating the brine to produce lithium carbonate, and then oxidizing the lithium carbonate to lithium hydroxide, or by extracting lithium phosphate from used lithium-ion batteries containing lithium and then adding a phosphate anion precipitant to produce lithium hydroxide.

[0005] However, conventional methods for producing lithium hydroxide leave various cations, such as calcium and magnesium, in the lithium hydroxide solution. These cations act as impurities during the lithium hydroxide production process, reducing the purity of the resulting lithium hydroxide. To remove these impurities, a precipitant, such as sodium hydroxide or sodium carbonate, is added to the lithium hydroxide solution, and the calcium and magnesium cations are then precipitated as hydroxides and removed. However, this method involves the inclusion of sodium ions in the lithium mixture, potentially reducing the purity of the resulting lithium hydroxide, and there are limitations to controlling the impurity concentration to an extremely low level.

[0006] Therefore, there is a need for a method for producing high purity lithium hydroxide without the inclusion of sodium ions and controlling the concentration of impurities to trace levels. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above-mentioned background, and an object of the present invention is to produce high-purity lithium hydroxide by removing cationic impurities from a lithium hydroxide solution containing cationic impurities and lithium ions.

[0008] Another object of the present invention is to control the concentration of calcium ions, which are impurities contained in the lithium hydroxide solution, to an extremely low level. [Means for solving the problem]

[0009] According to one embodiment of the present invention, there may be provided a method for producing lithium hydroxide, comprising: preparing a solution of lithium hydroxide containing impurities and lithium ions; and 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 impurities are calcium ions (Ca 2+ and wherein the concentration of calcium ions contained in the lithium hydroxide solution in the solution preparing step is 20 ppm or more and 25 ppm or less.

[0011] According to an embodiment of the present invention, there may be provided a method for preparing lithium hydroxide, wherein the lithium hydroxide solution is provided such that the amount of the lithium hydroxide solution passing through the chelating resin is 16.7 times or more and 83.3 times or less by volume relative to the amount of the chelating resin.

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

[0013] According to an embodiment of the present invention, there may be provided a method for preparing lithium hydroxide, wherein the acid concentration of the binding acidic solution is 60 g / L to 90 g / L.

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

[0015] According to an embodiment of the present invention, there may be provided a method for preparing lithium hydroxide, further comprising: passing distilled water through the chelating resin, the distilled water passing being performed between the binding acid solution passing step and the lithium hydroxide solution passing step.

[0016] According to an embodiment of the present invention, there may be provided a method for preparing lithium hydroxide, wherein the distilled water is provided in an amount of 1.5 to 6 times by volume relative to the amount of the chelating resin.

[0017] According to an embodiment of the present invention, there may be provided a method for preparing lithium hydroxide, further comprising, after the lithium hydroxide solution passing step, passing an acidic solution for separation through the chelating resin to which the impurities have been bound, wherein while the acidic solution for separation passes through the chelating resin, impurity ions bound to the chelating resin are exchanged for hydrogen ions in the acidic solution for separation.

[0018] According to an embodiment of the present invention, there may be provided a method for preparing lithium hydroxide, wherein the acid concentration of the acidic solution for separation is 60 g / L to 90 g / L.

[0019] According to an embodiment of the present invention, there may be provided a method for preparing lithium hydroxide, wherein the acidic solution for separation is provided such that the amount of the acidic solution for separation passing through the chelating resin is 5 to 6.7 times the amount of the chelating resin by volume. [Effects of the Invention]

[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 small level. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a flow chart sequentially illustrating a method for producing lithium hydroxide according to an embodiment of the present invention. [Figure 2] FIG. 2 is a graph showing the analysis results depending on the ratio of the amount of lithium hydroxide solution to the amount of chelating resin. [Figure 3] FIG. 3 is a graph showing the analysis results depending on the ratio of the amount of binding acidic solution to the amount of chelating resin. [Figure 4] FIG. 4 is a graph showing the analysis results according to the ratio of the amount of distilled water to the amount of chelating resin. [Figure 5] FIG. 5 is a graph showing the analysis results depending on the ratio of the amount of acidic solution for separation to the amount of chelating resin. DETAILED DESCRIPTION OF THE INVENTION

[0023] The examples of the present invention are provided for the purpose of explaining the technical concept of the present invention, and the scope of the invention is not limited to the examples presented below or the specific descriptions of these examples.

[0024] The present invention will now be described with reference to the drawings.

[0025] FIG. 1 is a flow chart sequentially illustrating a method for producing lithium hydroxide according to an embodiment of the present invention.

[0026] Referring to FIG. 1, the lithium hydroxide production method (S1) can produce a high-purity lithium hydroxide solution. In this specification, lithium hydroxide solution refers to a solution in which lithium hydroxide (LiOH) is dissolved, and the lithium hydroxide production method (S1) refers to the production of lithium hydroxide in the form of an aqueous solution. For example, the lithium hydroxide production method (S1) can be a series of lithium hydroxide purification methods that remove cationic impurities from a lithium hydroxide solution containing cationic impurities to obtain a high-purity lithium hydroxide solution. In this case, the lithium hydroxide production method (S1) can produce a lithium hydroxide solution from which cationic impurities have been removed.

[0027] Solution preparation stage (S100)

[0028] 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 several 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 yet another example, the lithium hydroxide solution can be obtained from used lithium-ion batteries. While the following description focuses on preparing a lithium hydroxide solution from used lithium-ion batteries, this is merely an example and does not limit the scope of the present invention.

[0029] In the solution preparation step (S100), lithium carbonate (Li2CO3) extracted from waste lithium-ion batteries can be used to obtain a lithium hydroxide solution. For example, calcium oxide (CaO) and water can be added to a lithium carbonate cake and reacted at 70 to 80°C for 2 to 3 hours to obtain a lithium hydroxide solution (see reaction formula 1 below).

[0030] Li2CO3(s) + CaO(s) + H2O = 2LiOH(aq) + CaCO3 (Reaction 1)

[0031] In the solution preparation step (S100), the lithium hydroxide solution contains aluminum ions (Al 3+ ), barium ions (Ba 2+ ), calcium ions (Ca 2+ ), iron ions (Fe 2+ , Fe 3+ ), magnesium ions (Mg 2+ ) and lead ions (Pb 2+ ) 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 to 25 ppm. Furthermore, in the solution preparation step (S100), the lithium hydroxide solution may contain lithium ions, and the concentration of such lithium ions may be 8 g / L to 12 g / L.

[0032] Lithium hydroxide solution passing step (S200)

[0033] The lithium hydroxide production method (S1) includes a lithium hydroxide solution passing step (S200) in which a lithium hydroxide solution is passed through a chelating resin so that ions contained in impurities are bound to the chelating resin. For example, the chelating resin may be a styrene-based IDA porous-type chelating resin. A chelating resin is a type of cation exchange resin, and cation exchange resins have different selectivity and adsorption properties depending on the type of ion. Generally, the selectivity of a cation exchange resin for calcium ions is greater than that for lithium ions. Because the selectivity of such a chelating resin for calcium ions is greater than that for lithium ions, calcium ions are exchanged for hydrogen ions bound to the chelating resin while the lithium hydroxide solution passes through the chelating resin, and the lithium ions contained in the lithium hydroxide solution can pass through the chelating resin.

[0034] In the lithium hydroxide solution passing step (S200), the lithium hydroxide solution can be provided to and passed through a chelating resin. As the lithium hydroxide solution passes through the chelating resin, ions contained in impurities are exchanged with hydrogen ions bound to the chelating resin, and the lithium ions contained in the lithium hydroxide solution can pass through the chelating resin. In other words, ions contained in impurities in the lithium hydroxide solution are bound to the chelating resin, and the hydrogen ions bound to the chelating resin are separated from the chelating resin. For example, ions contained in impurities in the lithium hydroxide solution can be calcium ions, and the calcium ions can be exchanged with hydrogen ions bound to the chelating resin. The same applies to other cations other than lithium ions.

[0035] In the lithium hydroxide solution passing step (S200), the lithium hydroxide solution may be provided such that the ratio of the amount of lithium hydroxide solution passing through the chelating resin to the amount of chelating 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 be 16.7 to 83.3 times the volume of the chelating resin. For example, if the volume ratio is less than 16.7, the amount of lithium hydroxide solution passing through the chelating resin relative to the amount of chelating resin becomes too small, which is uneconomical. If the volume ratio is more than 83.3, impurities cannot be sufficiently removed from the lithium hydroxide solution. Meanwhile, in this specification, the lithium hydroxide solution from which impurities have been removed by the chelating resin is referred to as the "post-passage lithium hydroxide solution" to distinguish it from the lithium hydroxide solution containing impurities in the solution preparation step (S100).

[0036] Binding acid solution passing step (S300)

[0037] The lithium hydroxide production method (S1) is a method for producing hydrogen ions (H + The method may include a binding acid solution passing step (S300) in which the binding acid solution is passed through the chelating resin so that the ions (Na ) are 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 is passing through the chelating resin, the ions originally bound to the chelating resin may be exchanged for hydrogen ions in the binding acid solution. For example, if the ions originally bound to the chelating resin are sodium ions (Na ), the ions may be exchanged for hydrogen ions in the binding acid solution. +), while the acidic binding solution passes through the chelating resin, hydrogen ions in the acidic binding solution may be ion-exchanged with 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 also be hydrogen ions. In this case, in the acidic binding solution passing step (S300), while the acidic binding solution passes through the chelating resin, the acidic binding solution removes the coating layer on the surface of the chelating resin. In addition, the acidic binding solution may be a solution of one or more of hydrochloric acid (HCl) and sulfuric acid (H2SO4). The acid concentration of such an acidic binding solution may be 60 g / L to 90 g / L.

[0038] In the binding acid solution passing step (S300), the binding acid solution may be provided so that the ratio of the amount of binding acid solution passing through the chelating resin to the amount of chelating resin is 4 to 8. That is, the amount of binding acid solution provided in the binding acid solution passing step (S300) may be 4 to 8 times the volume of the chelating resin. For example, if the volume ratio is less than 4, a sufficient amount of hydrogen ions cannot be bound to the chelating resin, and if the volume ratio is more than 8, the hydrogen ions will no longer bind to the chelating resin, which is not economical.

[0039] Distilled water passage stage (S400)

[0040] The lithium hydroxide production method (S1) may include a distilled water passing step (S400) of passing distilled water through the chelating resin after the binding acid solution passing step (S300) to remove the binding acid solution remaining on the chelating resin. 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 on the chelating resin refers to the binding acid solution that does not undergo ion exchange with the chelating resin while passing through the chelating resin and remains on the surface of the chelating resin. For example, if the binding acid solution that remains without binding to the chelating resin is mixed with the lithium hydroxide solution in the lithium hydroxide solution passing step (S200), sulfur (S) or chlorine (Cl) may act as impurities and contaminate the process solution in subsequent processes. In this case, by passing distilled water through the chelating resin to wash and remove the remaining binding acidic solution, it is possible to prevent sulfur or chlorine from being mixed into the lithium hydroxide solution that has passed through the chelating resin.

[0041] 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 chelating 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 of the chelating resin. For example, if the volume ratio is less than 1.5, the remaining acidic binding solution cannot be sufficiently removed, and if the volume ratio is more than 6, the amount of distilled water becomes too large, which is uneconomical.

[0042] Separation acid solution passing stage (S500)

[0043] The lithium hydroxide production method (S1) may include a separation acid solution passing step (S500) in which a separation acid solution is passed through a chelating resin to which impurities have been bound, so that the impurities bound to the chelating resin are separated from the chelating 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 chelating resin from the chelating resin in the lithium hydroxide solution passing step (S200) and reuse the chelating resin. While the separation acid solution passes through the chelating resin to which impurities have been bound, the impurity ions bound to the chelating resin are exchanged for hydrogen ions in the separation acid solution. That is, the hydrogen ions in the separation acid solution are bound to the chelating resin, and the calcium ions bound to the chelating resin are separated from the chelating resin. For example, the separation acid solution may be sulfuric acid (H2SO4) or hydrochloric acid (HCl). The acid concentration of the separation acid solution may be 60 g / L to 90 g / L.

[0044] In the separating acid solution passing step (S500), the separating acid solution may be provided so that the ratio of the amount of separating acid solution passing through the chelating resin to the amount of chelating resin is 5 to 6.7. That is, the amount of separating acid solution provided in the separating acid solution passing step (S500) may be 5 to 6.7 times the volume of the chelating resin. For example, if the volume ratio is less than 5, impurity ions cannot be sufficiently desorbed from the chelating resin, and if it is more than 6.7, the amount of separating acid solution becomes too large, which is uneconomical.

[0045] Hereinafter, examples of the method for producing lithium hydroxide according to the present invention will be described.

[0046] Analysis results based on the ratio of the amount of lithium hydroxide solution to the amount of chelating resin

[0047] [Table 1]

[0048] In Table 1, Examples 1 to 7 were obtained by varying the amount of lithium hydroxide solution used under the same experimental conditions. That is, Table 1 shows experiments conducted by varying the ratio of the amount of lithium hydroxide solution passing through the chelating resin to the amount of chelating resin. As can be seen from Table 1 and Figure 2, when the ratio of the amount of lithium hydroxide solution to the amount of chelating resin was between 16.7 and 83.3 (Examples 1 to 5), impurities were sufficiently removed, resulting in a calcium ion removal rate of 90.6% to 92.8% after the reaction. Therefore, when the ratio of the amount of lithium hydroxide solution to the amount of chelating resin was 16.7 or more, as in Example 1, it was possible to prevent the amount of lithium hydroxide solution passing through the chelating resin from becoming excessively small. When the ratio of the amount of lithium hydroxide solution to the amount of chelating resin was 83.3 or less, as in Example 5, impurities were sufficiently removed from the lithium hydroxide solution (removal rate of 90% or more), demonstrating a significant effect.

[0049] Analysis results based on the ratio of the amount of binding acid solution to the amount of chelating resin

[0050] [Table 2]

[0051] In Table 2, Examples 8 to 12 were tested under the same experimental conditions, varying the amount of binding acid solution. That is, Table 2 shows experiments varying the ratio of the amount of binding acid solution passing through the chelating resin to the amount of chelating resin. In these examples, a sulfuric acid solution with a concentration of 60 g / L was used as the binding acid solution. As can be seen from Table 2 and Figure 3, when the ratio of the amount of sulfuric acid solution to the amount of chelating resin was between 4 and 8 (Examples 9 to 11), the sulfuric acid solution reacted sufficiently, resulting in a sulfuric acid solution concentration of 52.7 g / L to 59.5 g / L after the reaction. Therefore, when the ratio of the amount of sulfuric acid solution to the amount of chelating resin was 4 or more, as in Example 9, a significant effect was observed on the hydrogen ion bonding rate. When the ratio of the amount of sulfuric acid solution to the amount of chelating resin was 8 or less, as in Example 11, the hydrogen ion bonding rate was maintained at a predetermined level, while preventing the amount of sulfuric acid solution from being excessively increased.

[0052] Analysis results based on the ratio of distilled water volume to chelating resin volume

[0053] [Table 3]

[0054] In Table 3, Examples 13 to 20 were tested under the same experimental conditions, varying the amount of distilled water. That is, Table 3 shows experiments conducted while varying the ratio of the amount of distilled water passing through the chelating resin to the amount of chelating resin. As can be seen from Table 3 and Figure 4, when the ratio of the amount of distilled water to the amount of chelating resin was between 1.5 and 6 (Examples 15 to 18), the sulfuric acid solution was sufficiently removed, and the concentration of the sulfuric acid solution after the reaction was between 17.7 g / L and 0.07 g / L. Therefore, when the ratio of the amount of distilled water to the amount of chelating resin was 1.5 or more, as in Example 15, a significant effect was observed in removing the remaining binding acid solution. When the ratio of the amount of distilled water to the amount of chelating resin was 6 or less, as in Example 18, the removal rate of the remaining binding acid solution was maintained at a predetermined level, while preventing the amount of distilled water being excessively increased.

[0055] Analysis results based on the ratio of the amount of acidic solution for separation to the amount of chelating resin

[0056] [Table 4]

[0057] In Table 4, Examples 21 to 25 were conducted under the same experimental conditions, varying the amount of acidic solution used. That is, Table 4 shows experiments conducted while varying the ratio of the amount of acidic solution used to pass through the chelating resin relative to the amount of chelating resin. In these examples, a 90 g / L sulfuric acid solution was used as the acidic solution. As can be seen from Table 4 and Figure 5, when the ratio of the amount of sulfuric acid solution to the amount of chelating resin was between 5 and 6.7 (Examples 23 and 24), calcium ions were sufficiently desorbed from the chelating resin, resulting in a cumulative calcium ion recovery rate of 88.2% to 88.8%. Therefore, when the ratio of the amount of acidic solution used to the amount of chelating resin was 5 or more, as in Example 23, impurities were sufficiently desorbed from the chelating resin, resulting in a significant effect. When the ratio of the amount of acidic solution used to the amount of chelating resin was 6.7 or less, as in Example 24, the impurity desorption rate was maintained at a predetermined level while preventing excessive addition of sulfuric acid solution.

[0058] Although the present invention has been described above with reference to the accompanying drawings, it will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical concept or essential characteristics thereof.

[0059] Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims rather than the above detailed description, and all modifications and variations that fall within 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. 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; While the lithium hydroxide solution is passing through the chelating resin, ions contained in the impurities are exchanged with ions bound to the chelating resin and are bound to the chelating resin, and the lithium ions pass through the chelating resin. Lithium hydroxide manufacturing method.

2. The impurities are calcium ions (Ca ２＋ ), In the solution preparation step, the concentration of the calcium ions contained in the lithium hydroxide solution is 20 ppm or more and 25 ppm or less. The method for producing lithium hydroxide according to claim 1.

3. The lithium hydroxide solution is provided so that the amount of the lithium hydroxide solution passing through the chelating resin is 16.7 times or more and 83.3 times or less by volume relative to the amount of the chelating resin. The method for producing lithium hydroxide according to claim 1.

4. The method further includes a binding acid solution passing step, which is performed between the solution preparing step and the lithium hydroxide solution passing step, of passing a 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 hydrogen ions bound to the chelating resin. The method for producing lithium hydroxide according to claim 1.

5. The acid concentration of the binding acid solution is 60 g / L to 90 g / L; The method for producing lithium hydroxide according to claim 4.

6. The acidic binding solution is provided so that the amount of the acidic binding solution passing through the chelating resin is 4 to 8 times the volume of the chelating resin. The method for producing lithium hydroxide according to claim 4.

7. The method further comprises passing distilled water through the chelating resin; The distilled water passing step is performed between the binding acid solution passing step and the lithium hydroxide solution passing step. The method for producing lithium hydroxide according to claim 4.

8. The distilled water is provided in such a manner that the volume ratio of the distilled water to the volume of the chelating resin is 1.5 to 6 times. The method for producing lithium hydroxide according to claim 7.

9. The method further comprises a separating acid solution passing step, which is performed after the lithium hydroxide solution passing step, of passing an acid solution for separation through the chelating resin to which the impurities are bound, While the separating acid solution passes through the chelating resin, the impurity ions bound to the chelating resin are exchanged with hydrogen ions of the separating acid solution. The method for producing lithium hydroxide according to claim 1.

10. The acid concentration of the separation acid solution is 60 g / L to 90 g / L; The method for producing lithium hydroxide according to claim 9.

11. The acidic solution for separation is provided so that the amount of the acidic solution for separation passing through the chelating resin is 5 times or more and 6.7 times or less by volume relative to the amount of the chelating resin. The method for producing lithium hydroxide according to claim 9.

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