Lithium recovery method

Abstract

The present invention relates to a method for recovering lithium. Specifically, according to one embodiment of the present invention, there is provided a step of preparing a lithium-containing solution containing lithium ions; a step of exchanging ions contained in the chelating resin with the lithium ions so that the lithium ions are bound to the chelating resin while the lithium-containing solution passes through the chelating resin; and a step of passing an acidic solution through the chelating resin to which the lithium ions are bound so that the lithium ions are separated from the chelating resin, thereby providing a method for recovering lithium.

Description

Technical Field

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

Background Art

[0002] Lithium (Li) is an essential raw material for industry used in various industries. Conventionally, lithium was mostly used in ceramics, chemical additives, etc., but recently, with the trend of wireless and electrification in major industries, it is widely used in electronic devices such as mobile phones and laptops. In particular, the demand for lithium batteries used in Battery Electric Vehicles (BEVs) and the like is increasing, and there is a need for the development of technologies to effectively and economically extract lithium from resources containing lithium.

[0003] Generally, naturally occurring lithium is distributed in trace amounts in soil, rocks, and natural water. Therefore, lithium must be recovered from soil, rocks, or natural trees where lithium is concentrated, and the recovered lithium must be processed into a compound form for use. For example, commercially available lithium is concentrated in minerals or brines.

[0004] The method for recovering lithium from ore includes a plurality of steps for raw materials containing lithium, such as spodumene, lepidolite, amblygonite, or petalite. The method for recovering lithium from ore also includes steps such as a mining step, a crushing step, a separation step, an ore dressing step, and then steps such as a heating step, a concentration step, a filtration step, and an additive addition step for further processing. Such a method for recovering lithium from ore has problems in that it requires various steps, resulting in an increase in equipment investment and operating costs, and generating a large amount of acidic sludge, causing serious environmental pollution.

[0005] To solve the problems arising from the method of recovering lithium from ores, a method of recovering lithium from the brine of a salt lake has been developed. In the conventional method of recovering lithium from brine, the brine was naturally evaporated to increase the concentration of lithium in the brine in order to form a compound in the form of lithium carbonate (Li2CO3), and then precipitated as lithium carbonate. However, the process of naturally evaporating the brine requires a long period of over one year, and there is a problem that lithium is precipitated together with other substances during the concentration process.

[0006] Therefore, there is a need for a lithium recovery method that can effectively recover lithium from a low-concentration lithium-containing solution in a short time.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been invented in view of the above background, and aims to efficiently recover lithium even when the lithium concentration of a lithium-containing solution is low.

[0008] Also, it aims to recover lithium from a lithium-containing solution in a short time without naturally evaporating the lithium-containing solution for a long time.

[0009] Also, it aims to minimize the amount of sludge generated and prevent environmental pollution.

Means for Solving the Problems

[0010] According to an embodiment of the present invention, there may be provided a lithium recovery method including the steps of preparing a lithium-containing solution containing lithium ions; exchanging the ions contained in the chelating resin with the lithium ions so that the lithium ions are bound to the chelating resin while the lithium-containing solution passes through the chelating resin; and passing an acidic solution through the chelating resin to which the lithium ions are bound so that the lithium ions are separated from the chelating resin.

[0011] According to an embodiment of the present invention, there may be provided a lithium recovery method further including a step of mixing a basic solution with the lithium-containing solution to adjust the pH of the lithium-containing solution, wherein the lithium-containing solution passes through the chelating resin in a state where the pH is adjusted to 10 to 13 by the basic solution.

[0012] According to an embodiment of the present invention, there may be provided a lithium recovery method, wherein the lithium-containing solution is provided such that the ratio of the amount of the lithium-containing solution passing through the chelating resin to the amount of the chelating resin is 4.17 to 8.33.

[0013] According to an embodiment of the present invention, there may be provided a lithium recovery method, wherein the ratio of the amount of lithium ions bound to the chelating resin to the amount of the chelating resin is 1 to 1.3.

[0014] According to an embodiment of the present invention, there may be provided a lithium recovery method, wherein the acidic solution is provided such that the ratio of the amount of the acidic solution passing through the chelating resin to the amount of the chelating resin is 1.5 to 2.5.

[0015] According to an embodiment of the present invention, there may be provided a lithium recovery method further including a step of passing water through the chelating resin to which lithium ions are bound so that the lithium ions are separated from the chelating resin, and the step of passing water through the chelating resin is performed after the step of passing an acidic solution through the chelating resin.

[0016] According to an embodiment of the present invention, there may be provided a lithium recovery method further including a step of providing a supply substance containing one or more of phosphoric acid and phosphates to a lithium purification solution containing lithium ions separated from the chelating resin, wherein the lithium ion concentration in the lithium-containing solution is 0.39 g / L or less.

[0017] According to an embodiment of the present invention, there may be provided a lithium recovery method, wherein the lithium-containing solution includes seawater or brine having a sodium (Na) concentration of 30 g / L to 50 g / L.

[0018] According to an embodiment of the present invention, a lithium recovery method can be provided in which the ion contained in the chelating resin to be exchanged with the lithium ion is a hydrogen ion.

[0019] According to an embodiment of the present invention, a lithium recovery method can be provided in which the acid concentration of the acidic solution is 1.472 eq / L to 2.208 eq / L.

Effects of the Invention

[0020] According to the present invention, there is an effect that lithium can be efficiently recovered even when the lithium concentration of the lithium-containing solution is low.

[0021] In addition, there is an effect that lithium can be recovered from the lithium-containing solution in a short time without allowing the lithium-containing solution to naturally evaporate for a long time.

[0022] In addition, there is an effect that the amount of sludge generated can be minimized to prevent environmental pollution.

Brief Description of the Drawings

[0023] FIG. 1 is a sequence diagram sequentially showing a lithium recovery method according to an embodiment of the present invention.

[0024] FIG. 2 is a graph showing the lithium binding ability depending on pH.

[0025] FIG. 3 is a graph showing the lithium binding ability depending on the ratio of the sample amount to the amount of chelating resin.

[0026] FIG. 4 is a graph showing the hydrogen ion exchange rate depending on the ratio of the acidic solution to the amount of chelating resin.

Modes for Carrying Out the Invention

[0027] Examples of the present invention are illustrated for the purpose of explaining the technical idea of the present invention. The scope of rights according to the present invention is not limited to the examples presented below or the specific descriptions of these examples.

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

[0029] FIG. 1 is a sequence diagram sequentially showing a lithium recovery method according to an embodiment of the present invention.

[0030] Referring to FIG. 1, in the lithium recovery method (S1), lithium is recovered from a lithium-containing solution. For example, in the lithium recovery method (S1), lithium can be recovered from seawater or brine in the form of lithium phosphate (Li3PO4).

[0031] The lithium recovery method (S1) may include a step (S100) of preparing a lithium-containing solution containing lithium ions. The lithium-containing solution herein contains lithium ions. As an example, the concentration of lithium ions in the lithium-containing solution may be 0.39 g / L or less. Further, the lithium-containing solution may be seawater or brine having a sodium (Na) concentration of 30 g / L to 50 g / L. In the step (S100) of preparing such a lithium-containing solution, the lithium-containing solution can be provided such that the ratio of the amount of the lithium-containing solution passing through the chelating resin to the amount of the chelating resin is 4.17 to 8.33. That is, the amount of the lithium-containing solution provided in the step (S100) of preparing the lithium-containing solution may be 4.17 to 8.33 times the amount of the chelating resin in terms of volume ratio.

[0032] The lithium recovery method (S1) may include a step (S200) of mixing a basic solution into the lithium-containing solution to adjust the pH of the lithium-containing solution. In such a step (S200) of mixing a basic solution into the lithium-containing solution, the basic solution is mixed into the lithium-containing solution so that the pH of the lithium-containing solution is adjusted to 10 to 13. For example, the basic solution may be sodium hydroxide (NaOH). Further, the step (S200) of mixing a basic solution into the lithium-containing solution may be performed before the basic solution passes through the chelating resin. In this case, the lithium-containing solution passes through the chelating resin in a state where the pH has been adjusted to 10 to 13 by the basic solution. In one example, the chelating resin in this specification may be an ion exchange resin obtained by adding divinyl benzene (DVB) to polystyrene and polymerizing it.

[0033] The lithium recovery method (S1) may include a step (S300) of exchanging the ions contained in the chelating resin with lithium ions so that the lithium ions are bound to the chelating resin while the lithium-containing solution passes through the chelating resin. In the step (S300) of exchanging the ions contained in the chelating resin with lithium ions, the lithium-containing solution whose pH has been adjusted in the step (S200) of mixing a basic solution into the lithium-containing solution passes through the chelating resin. While such a lithium-containing solution passes through the chelating resin, the lithium ions contained in the lithium-containing solution are exchanged with the ions contained in the chelating resin. In other words, the lithium ions contained in the lithium-containing solution bind to the chelating resin, and the ions bound to the chelating resin are separated from the chelating resin. In this case, the lithium ions contained in the lithium-containing solution are separated from the lithium-containing solution in a state of being bound to the chelating resin. For example, according to one embodiment of the present invention, the chelating resin may contain hydrogen ions, and the hydrogen ions may be exchanged with the lithium ions of the lithium-containing solution.

[0034] The lithium recovery method (S1) may include a step (S400) of passing an acidic solution through a chelating resin to which lithium ions are bound so that the lithium ions are separated from the chelating resin. In the step (S400) of passing the acidic solution through the chelating resin, the acidic solution is passed through the chelating resin to which lithium ions are bound, and while the acidic solution passes through the chelating resin, the lithium ions are separated from the chelating resin. The concentration of the acid in such an acidic solution is 1.472 eq / L to 2.208 eq / L. For example, the acidic solution may be sulfuric acid (H2SO4) with a concentration of 72 g / L or more and 108 g / L or less. Also, in the step (S400) of passing the acidic solution through the chelating resin, the ratio of the amount of the acidic solution passing through the chelating resin to the amount of the chelating resin may be provided to be 1.5 to 2.5. That is, the amount of the acidic solution provided in the step (S400) of passing the acidic solution through the chelating resin may be 1.5 to 2.5 times the amount of the chelating resin in terms of volume ratio.

[0035] The lithium recovery method (S1) may include a step (S500) of passing water through a chelating resin to which lithium ions are bound so that the lithium ions are separated from the chelating resin. In the step (S500) of passing water through the chelating resin, water is passed through the chelating resin to which lithium ions are bound, and while the water passes through the chelating resin, the lithium ions are separated from the chelating resin. Such a step (S500) of passing water through the chelating resin may be performed after the step (S400) of passing the acidic solution through the chelating resin. In this case, the acidic solution passes through the chelating resin and the lithium ions are primarily separated from the chelating resin (S400), and water passes through the chelating resin and the lithium ions are secondarily separated from the chelating resin (S500). In such a step (S500) of passing water through the chelating resin, the ratio of the amount of water passing through the chelating resin to the amount of the chelating resin may be provided to be 1.5 to 2.5. That is, the amount of water provided in the step (S500) of passing water through the chelating resin may be 1.5 to 2.5 times the amount of the chelating resin in terms of volume ratio.

[0036] The lithium recovery method (S1) may include a step (S600) of providing a feed substance containing one or more of phosphoric acid and phosphates to a lithium purification solution. Here, the lithium purification solution is a solution containing lithium ions separated from a chelating resin. In the step (S600) of providing a phosphorus feed substance, the phosphorus feed substance may react with lithium ions to produce lithium phosphate (Li3PO4). Here, the phosphorus feed substance contains one or more of phosphorus, phosphoric acid, and phosphates, and the phosphate may be one or more of potassium phosphate, sodium phosphate, and ammonium phosphate.

[0037] Thus, the lithium recovery method (S1) can recover lithium ions in the form of lithium phosphate from seawater or brine containing low-concentration lithium ions with a lithium ion concentration of 0.39 g / L or less.

[0038] Hereinafter, examples of the lithium recovery method of the present invention will be described.

[0039] Analysis results by pH

[0040]

Table 1

[0041] Examples 1 to 7 in Table 1 above are experiments conducted by changing only the pH of the lithium-containing solution under the same experimental conditions. Here, the pH adjustment is made at the stage of mixing the basic solution with the lithium-containing solution (S200). The lithium recovery rate (%) in this specification indicates the percentage of the amount of lithium bound to the chelating resin with respect to the amount of lithium contained in the lithium-containing solution before the reaction. Also, the lithium binding ability indicates the amount of lithium bound to the chelating resin with respect to the amount of the chelating resin, and means the degree to which lithium is recovered by the chelating resin. That is, when the absolute amount (mg) of lithium in the sample to be treated is the same, it means that the higher the lithium binding ability, the more lithium is recovered by the same chelating resin. From Table 1 and Figure 2 above, it can be seen that the lithium recovery rate and the lithium binding ability change as the pH changes. In the case of the lithium-containing solution (Examples 4 to 6) whose pH is adjusted to 10 to 13, it can be seen that it is more preferable in terms of the lithium recovery rate and the lithium binding ability.

[0042] Analysis results by the ratio of the sample amount to the amount of chelating resin

[0043]

Table 2

[0044] Examples 8 to 12 in Table 2 above were experiments with the sample amount changed under the same experimental conditions. The sample amount in this specification means the amount of the lithium-containing solution passing through the chelating resin. That is, Table 2 above was an experiment with the ratio of the amount of the lithium-containing solution passing through the chelating resin to the amount of the chelating resin changed. From Table 2 and FIG. 3 above, it can be seen that the lithium-binding ability changes as the sample amount relative to the amount of the chelating resin changes. Further, it can be seen that when the ratio of the sample amount to the amount of the chelating resin is 4.17 to 8.33 (Examples 9 to 11), the lithium-binding ability is more preferable. When the ratio of the sample amount to the amount of the chelating resin is 4.17 or more as in Example 9, the lithium-binding ability exhibits a remarkable effect of 1 or more. When the ratio of the sample amount to the amount of the chelating resin is 8.33 or less as in Example 11, it is possible to prevent the amount of the sample to be introduced from becoming excessively large while maintaining the lithium-binding ability at a predetermined level.

[0045] Analysis results by the ratio of the acidic solution to the amount of chelating resin

[0046]

Table 3

[0047] Examples 13 to 17 in Table 3 above were experiments with the liquid amount changed under the same experimental conditions. The liquid amount in this specification means the amount of the acidic solution passing through the chelating resin. That is, Table 3 above is the experimental result with the ratio of the amount of the acidic solution passing through the chelating resin to the amount of the chelating resin changed. From Table 3 and FIG. 4 above, it can be seen that the hydrogen ion exchange rate changes as the amount of the acidic solution consumed changes. It can be seen that when the ratio of the liquid amount to the amount of the chelating resin is 1.5 to 2.5 in terms of volume ratio (Examples 15 to 17), the hydrogen ion exchange rate is more preferable. When the ratio of the liquid amount to the amount of the chelating resin is 1.5 or more in terms of volume ratio as in Example 15, the hydrogen ion exchange rate becomes significantly higher, and there is an effect of improving the amount of lithium recovered. Also, when the ratio of the liquid amount to the amount of the chelating resin is 2.5 or less in terms of volume ratio as in Example 17, it is possible to prevent the amount of the acidic solution to be introduced from becoming excessively large. The embodiments of the present invention have been described above with reference to the accompanying drawings. Those of ordinary skill in the art to which the present invention pertains should be able to understand that the present invention can be implemented in other specific forms without changing its technical idea and essential features.

[0048] Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included within the scope of the present invention.

Claims

Claim 1 Preparing a lithium-containing solution containing lithium ions; During the passage of the lithium-containing solution through the chelating resin, exchanging the lithium ions with the ions contained in the chelating resin so that the lithium ions are bound to the chelating resin; and Passing an acidic solution through the chelating resin to which the lithium ions are bound so that the lithium ions are separated from the chelating resin, A lithium recovery method. Claim 2 Further comprising mixing a basic solution with the lithium-containing solution to adjust the pH of the lithium-containing solution, The lithium-containing solution passes through the chelating resin with the pH adjusted to 10 to 13 by the basic solution, The lithium recovery method according to claim 1. Claim 3 The lithium-containing solution is provided such that the ratio of the amount of the lithium-containing solution passing through the chelating resin to the amount of the chelating resin is 4.17 to 8.33, The lithium recovery method according to claim 1. Claim 4 The ratio of the amount of lithium ions bound to the chelating resin to the amount of the chelating resin is 1 to 1.3, The lithium recovery method according to claim 2 or 3. Claim 5 The acidic solution is provided such that the ratio of the amount of the acidic solution passing through the chelating resin to the amount of the chelating resin is 1.5 to 2.5, The lithium recovery method according to claim 3. Claim 6 Further comprising passing water through the chelating resin to which the lithium ions are bound so that the lithium ions are separated from the chelating resin, The step of passing water through the chelating resin is performed after the step of passing an acidic solution through the chelating resin, The lithium recovery method according to claim 1. Claim 7 Further comprising providing a phosphorus supply substance containing one or more of phosphorus and phosphate to the lithium purification solution containing lithium ions separated from the chelating resin, The lithium ion concentration in the lithium-containing solution is 0.39 g / L or less, The lithium recovery method according to claim 1. Claim 8 The lithium-containing solution includes seawater or brine having a sodium (Na) concentration of 30 g / L to 50 g / L, The lithium recovery method according to claim 7. Claim 9 The ions contained in the chelating resin exchanged with the lithium ions are hydrogen ions, The lithium recovery method according to claim 1. Claim 10 The acid concentration of the acidic solution is 1.472 eq / L to 2.208 eq / L. The lithium recovery method according to claim 1.

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