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 industries used in various industries. Conventionally, lithium has been widely used in ceramics, chemical additives, etc., but recently, with the trend of wireless and electrification in major industries, it has been widely used in electronic devices such as mobile phones and laptops. In particular, the demand for lithium batteries used in Battery Electric Vehicles (BEVs) has increased, 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 multiple 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, a beneficiation step, and then steps such as a heating step, a concentration step, a filtration step, and an additive input step for detailed 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] On the other hand, to address the problems arising from methods of recovering lithium from ore, methods for recovering lithium from saltwater in salt lakes have been developed. In conventional methods of recovering lithium from saltwater, the saltwater is allowed to evaporate naturally to increase the concentration of lithium in the saltwater, and then the lithium carbonate (Li2CO3) is precipitated. However, the process of allowing the saltwater to evaporate naturally takes a long time, more than a year, and there was a problem with lithium precipitating along with other substances during the concentration process.

[0006] Therefore, there is a need for a lithium recovery method that can effectively recover lithium from low-concentration lithium-containing solutions in a short amount of time. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This invention was conceived in light of the aforementioned background, and aims to efficiently recover lithium even when the lithium concentration in a lithium-containing solution is low.

[0008] Furthermore, the aim is to recover lithium from a lithium-containing solution in a short time without allowing the solution to evaporate naturally for a long period of time.

[0009] Furthermore, the aim is to minimize the amount of sludge generated and prevent environmental pollution. [Means for solving the problem]

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

[0011] According to one embodiment of the present invention, a lithium recovery method is provided, further comprising the 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 chelate resin with its pH adjusted to 10-13 by the basic solution.

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

[0013] According to one embodiment of the present invention, a lithium recovery method is provided in which the ratio of the amount of lithium ions bound to the chelate resin to the amount of chelate resin is 1 to 1.3.

[0014] According to one embodiment of the present invention, a lithium recovery method may be provided in which the acidic solution is provided such that the ratio of the amount of acidic solution passing through the chelate resin to the amount of chelate resin is 1.5 to 2.5.

[0015] According to one embodiment of the present invention, a lithium recovery method is provided, further comprising the step of passing water through a chelate resin to which lithium ions are bound so as to separate the lithium ions from the chelate resin, wherein the step of passing water through the chelate resin is performed after the step of passing an acidic solution through the chelate resin.

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

[0017] According to one embodiment of the present invention, a lithium recovery method may be provided in which the lithium-containing solution comprises seawater or brine with 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 chelate 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] Also, 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] Also, 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 chelate 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 chelate 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 an order 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 in this specification 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 with 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] A lithium recovery method (S1) may include a step (S200) of mixing a basic solution with a lithium-containing solution to adjust the pH of the lithium-containing solution. In such a step (S200), the basic solution is mixed with the lithium-containing solution so that the pH of the lithium-containing solution is adjusted to 10-13. For example, the basic solution may be sodium hydroxide (NaOH). Alternatively, the step (S200) of mixing a basic solution with a lithium-containing solution may be performed before the basic solution passes through the chelate resin. In this case, the lithium-containing solution passes through the chelate resin with its pH adjusted to 10-13 by the basic solution. In one example, the chelate resin described herein may be an ion exchange resin polymerized by adding DVB (Divinyl benzene) to Polystyrene.

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

[0034] The lithium recovery method (S1) may include a step (S400) of passing an acidic solution through a chelate resin to which lithium ions are bound, so that lithium ions are separated from the chelate resin. In the step of passing an acidic solution through the chelate resin (S400), the acidic solution is passed through the chelate resin to which lithium ions are bound, and lithium ions are separated from the chelate resin while the acidic solution passes through the chelate 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 to 108 g / L. In addition, in the step of passing an acidic solution through the chelate resin (S400), the acidic solution may be provided such that the ratio of the amount of acidic solution passing through the chelate resin to the amount of chelate resin is 1.5 to 2.5. That is, the amount of acidic solution provided in the step of passing an acidic solution through the chelate resin (S400) may be 1.5 to 2.5 times the amount of chelate resin by volume.

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

[0036] The lithium recovery method (S1) may include a step (S600) of providing a supply 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 chelate resin. In the step of providing the phosphorus supply substance (S600), the phosphorus supply substance may react with lithium ions to produce lithium phosphate (Li3PO4). Here, the phosphorus supply 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 saltwater containing low concentrations of lithium ions, where the lithium ion concentration is 0.39 g / L or less.

[0038] The following describes an example of the lithium recovery method of the present invention.

[0039] pH analysis results

[0040] [Table 1]

[0041] Examples 1 to 7 in Table 1 were experiments conducted under the same experimental conditions, with only the pH of the lithium-containing solution being changed. Here, the pH adjustment is performed at the stage of mixing the lithium-containing solution with a basic solution (S200). The lithium recovery rate (%) specified herein represents the percentage of lithium bound to the chelating resin relative to the amount of lithium contained in the lithium-containing solution before the reaction. The lithium binding capacity represents the amount of lithium bound to the chelating resin relative to the amount of chelating resin, and indicates the degree to which lithium is recovered in the chelating resin. That is, if the absolute amount of lithium (mg) in the sample to be treated is the same, a higher lithium binding capacity means that more lithium is recovered in the same chelating resin. From Table 1 and Figure 2, it can be seen that the lithium recovery rate and lithium binding capacity change as the pH changes. In the case of lithium-containing solutions adjusted to pH 10 to 13 (Examples 4 to 6), it can be seen that they are even more preferable in terms of lithium recovery rate and lithium binding capacity.

[0042] Analysis results based on the ratio of sample amount to chelate resin amount

[0043] [Table 2]

[0044] Examples 8 to 12 in Table 2 were conducted under the same experimental conditions, but with varying sample amounts. In this specification, "sample amount" refers to the amount of lithium-containing solution passing through the chelate resin. That is, Table 2 shows experiments conducted while varying the ratio of the amount of lithium-containing solution passing through the chelate resin to the amount of chelate resin. From Table 2 and Figure 3, it can be seen that the lithium-binding capacity changes when the sample amount relative to the chelate resin amount changes. Furthermore, it can be seen that the lithium-binding capacity is more favorable when the ratio of sample amount to chelate resin amount is between 4.17 and 8.33 (Examples 9 to 11). When the ratio of sample amount to chelate resin amount is 4.17 or higher, as in Example 9, a significant effect of lithium-binding capacity of 1 or higher is achieved. When the ratio of sample amount to chelate resin amount is 8.33 or lower, as in Example 11, it is possible to maintain the lithium-binding capacity at a predetermined level while preventing the amount of sample added from becoming excessively large.

[0045] Analysis results based on the ratio of acidic solution to chelate resin amount

[0046] [Table 3]

[0047] Examples 13-17 in Table 3 above are experiments in which the liquid volume was changed under the same experimental conditions. In this specification, liquid volume refers to the amount of acidic solution passing through the chelating resin. That is, Table 3 above shows the experimental results when the ratio of the amount of acidic solution passing through the chelating resin to the amount of chelating resin was changed. From Table 3 and Figure 4 above, it can be seen that the hydrogen ion exchange rate changes when the amount of acidic solution consumed changes. It can be seen that the hydrogen ion exchange rate is more favorable when the ratio of liquid volume to chelating resin volume is 1.5 to 2.5 in volume (Examples 15-17). When the ratio of liquid volume to chelating resin volume is 1.5 or higher in volume, as in Example 15, the hydrogen ion exchange rate becomes significantly higher, and the amount of lithium recovered is improved. Also, when the ratio of liquid volume to chelating resin volume is 2.5 or lower in volume, as in Example 17, it is possible to prevent the amount of acidic solution added from becoming excessively large. Although embodiments of the present invention have been described above with reference to the attached drawings, those with ordinary skill in the art to which the present invention belongs should be able to understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features.

[0048] Therefore, the embodiments described above should be understood to be illustrative and not limiting in all respects. The scope of the present invention is indicated by the claims rather than by the above detailed description, and all modifications or modified forms derived from the meaning and scope of the claims and the concept of equivalents thereto should be interpreted as being included within the scope of the present invention.

Claims

1. The step of preparing a lithium-containing solution that includes lithium ions; A step in which, while the lithium-containing solution passes through the chelate resin, the lithium ions are exchanged with the ions contained in the chelate resin so that the lithium ions bind to the chelate resin; A step of passing an acidic solution through the chelate resin to which the lithium ions are bound so that the lithium ions are separated from the chelate resin; and The step includes passing water through the chelate resin to which the lithium ions are bound, so that the lithium ions are separated from the chelate resin. A lithium recovery method wherein the step of passing water through the chelate resin is performed after the step of passing an acidic solution through the chelate resin.

2. The method further includes the step of mixing a basic solution with the lithium-containing solution in order to adjust the pH of the lithium-containing solution. The lithium-containing solution passes through the chelate resin after its pH has been adjusted to 10-13 by the basic solution. The lithium recovery method according to claim 1.

3. The lithium-containing solution is provided such that the ratio of the amount of lithium-containing solution passing through the chelate resin to the amount of chelate resin is 4.17 to 8.

33. The lithium recovery method according to claim 1.

4. The ratio of the mass of lithium ions bonded to the chelate resin to the volume of the chelate resin is 1 g / L to 1.3 g / L. The lithium recovery method according to claim 2 or 3.

5. The acidic solution is provided such that the ratio of the amount of acidic solution passing through the chelate resin to the amount of chelate resin is 1.5 to 2.

5. The lithium recovery method according to claim 3.

6. The step further includes providing a phosphorus-supplying substance containing one or more of phosphorus and phosphates to a lithium purification solution containing lithium ions separated from the chelate 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.

7. The lithium-containing solution includes seawater or brine with a sodium (Na) concentration of 30 g / L to 50 g / L. The lithium recovery method according to claim 6.

8. The ions contained in the chelate resin that are exchanged for the lithium ions are hydrogen ions. The lithium recovery method according to claim 1.

9. The acid concentration of the aforementioned acidic solution is 1.472 eq / L to 2.208 eq / L. The lithium recovery method according to claim 1.

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