Method for adsorbing / desorbing lithium

Abstract

The present invention relates to a method for adsorbing and desorbing lithium, and can provide a method for adsorbing and desorbing lithium, comprising: an adsorption step of passing a lithium-containing solution through an aluminum-based adsorbent to obtain an adsorbent to which lithium is adsorbed; and a desorption step of passing a medium through the lithium-adsorbed adsorbent to obtain a lithium-containing desorption liquid, wherein the medium used in the desorption step contains a salt.

Description

Lithium adsorption and desorption method

[0001] It is about the method of adsorption and desorption of lithium.

[0002] With the recent rapid growth of electric vehicles and related markets, demand for lithium secondary batteries is rapidly increasing. Consequently, demand for lithium hydroxide, one of the raw materials for lithium, a key raw material for lithium secondary batteries, is also rapidly increasing.

[0003] This lithium hydroxide is produced by chemically converting lithium carbonate produced in limited areas such as Chile and Argentina into calcium hydroxide, and it is known that direct production from raw materials is impossible.

[0004] Therefore, there is an urgent need to develop a technology that can economically and efficiently produce lithium hydroxide from a lithium-containing solution.

[0005] Among these methods, selective adsorption and desorption technology of lithium using adsorbents is being studied.

[0006] In a technology for recovering lithium by adsorption and desorption of lithium using an adsorbent, the present invention aims to provide a process for effectively recovering lithium by providing a more effective desorption technology.

[0007] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0008] In order to clearly explain the present invention, parts that are not related to the description are omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0009] Additionally, throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0010] Hereinafter, a method for adsorbing and desorbing lithium according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0011] First, a step of adsorbing lithium from a lithium-containing solution is performed.

[0012] Specifically, a lithium-containing solution is passed through an aluminum-based adsorbent to adsorb lithium onto the aluminum-based adsorbent.

[0013] At this time, the lithium concentration of the lithium-containing solution may be in the range of 0.04 g / L to 2.0 g / L, more specifically, 0.1 g / L to 1.0 g / L. If the lithium concentration of the lithium-containing solution is less than 0.1 g / L, the adsorption rate may be slow, which may reduce productivity. In addition, if the lithium concentration of the lithium-containing solution exceeds 2.0 g / L, although productivity increases, there is a problem in that the consumption of the adsorbent increases, which relatively reduces economic feasibility. Therefore, it is preferable that the lithium concentration included in the lithium-containing solution satisfies the above range.

[0014] The above aluminum-based adsorbent is intended to adsorb lithium dissolved in the lithium-containing solution, and may include, for example, aluminum hydroxide. When an aluminum-based adsorbent containing aluminum hydroxide is used as in the present embodiment, the amount of lithium dissolved in the lithium-containing solution is high, and there is little aluminum loss in the desorption process described below, so the life of the adsorbent is long, and the lithium extraction process has the advantage of being economically efficient.

[0015] Additionally, the aluminum-based adsorbent may be a molded body including adsorbent powder and a binder.

[0016] The above adsorbent powder may be, for example, an adsorbent powder containing aluminum hydroxide. The advantages of using an adsorbent powder containing aluminum hydroxide are the same as those described above.

[0017] The binder is used to form a molded body of the adsorbent powder into an appropriate shape and serves to bind the adsorbent powder together. The binder may include, for example, at least one of polyvinyl chloride (PVC), polysulfone, and polyaniline. In particular, in the present embodiment, the binder preferably includes polyvinyl chloride (PVC), which can provide excellent binding strength between the adsorbent powders.

[0018] Meanwhile, the step of passing a lithium-containing solution through an aluminum-based adsorbent to adsorb lithium onto the aluminum-based adsorbent includes, for example, the reaction of the following reaction formula 1.

[0019] [Reaction Formula 1]

[0020] (1-x)LiCl·Al(OH)3·nH2O + Li + → LiCl·Al(OH)3·nH2O + (1-x)Li +

[0021] Next, a step of obtaining a lithium-containing desorption liquid is performed.

[0022] Specifically, a lithium-containing desorbent can be obtained by passing a medium (e.g., distilled water or an aqueous solution containing a lithium salt) through the lithium-adsorbed aluminum adsorbent.

[0023] At this time, the amount of distilled water passed through the lithium-adsorbed aluminum adsorbent may be 0.5 to 100 times the volume of the adsorbent, more specifically, 2 to 40 times the volume of the adsorbent.

[0024] When performing a desorption process on an aluminum-based adsorbent with lithium adsorbed therein using distilled water less than 0.5 times the volume of the adsorbent, there is a problem in that the amount of lithium adsorbed on the adsorbent is reduced. Furthermore, when using distilled water exceeding 100 times the volume of the adsorbent, there is a problem in that the lithium desorbed during the desorption process is diluted, resulting in a lower concentration of lithium in the lithium-containing desorbent.

[0025] The concentration of lithium contained in the lithium-containing desorption liquid obtained by the above method may be in the range of 0.2 g / L to 2.0 g / L, more specifically, 0.4 g / L to 1.0 g / L. When the concentration of lithium contained in the lithium-containing desorption liquid satisfies the above range, the recovery rate of lithium hydroxide obtained after the subsequent process described below is excellent.

[0026] The step of passing distilled water through the lithium-adsorbed aluminum adsorbent to obtain a lithium-containing desorbent includes, for example, the reaction of the following reaction formula 2.

[0027] [Reaction Formula 2]

[0028] LiCl·Al(OH)3·nH2O + H2O → (1-x)LiCl·Al(OH)3·nH2O + xLiCl

[0029] In one embodiment of the present invention, a more specific desorption method can be provided for this lithium adsorption and desorption process.

[0030] In one embodiment of the present invention, a method for adsorption and desorption of lithium is provided, comprising: an adsorption step of passing a lithium-containing solution through an aluminum-based adsorbent to obtain an adsorbent having lithium adsorbed thereon; and a desorption step of passing a medium through the lithium-adsorbed adsorbent to obtain a lithium-containing desorbent; wherein the medium used in the desorption step includes a salt.

[0031] When a medium containing a lithium salt, rather than simply distilled water, is used, the lithium concentration in the resulting desorption solution can be increased. This improvement in lithium concentration in the desorption solution can reduce the load on the subsequent concentration process.

[0032] In addition, in one embodiment of the present invention, a method for adsorption and desorption of lithium is provided, comprising: an adsorption step of passing a lithium-containing solution through an aluminum-based adsorbent to obtain an adsorbent having lithium adsorbed thereon; and a desorption step of passing a medium through the lithium-adsorbed adsorbent to obtain a lithium-containing desorbent; wherein the desorption step is performed multiple times, and the multiple desorption steps include a pre-desorption step and a post-desorption step, and the concentrations of salt in the medium used in the pre-desorption step and the post-desorption step are different.

[0033] Specifically, after the above-described adsorption step, a multi-stage desorption process is performed using a medium. At this time, if the lithium concentration within the medium is varied based on a certain interval, the lithium concentration of the final lithium desorption solution obtained can be increased.

[0034] If the lithium concentration of the desorption solution is high, it means that the amount of water that needs to be removed in the subsequent concentration step is reduced, which can significantly improve the process burden of the subsequent process.

[0035] Specifically, the concentration of salt in the medium of the pre-desorption step may be higher than the concentration of salt in the medium of the post-desorption step. In the concentration of salt in the medium, the reference salt may be a lithium salt.

[0036] At this time, the number of shear desorption steps can be determined by comparing the lithium concentration of the shear desorption liquid obtained through the shear desorption step with the lithium concentration of the post-desorption liquid obtained through the post-desorption step.

[0037] As described above, when obtaining a desorption solution, the desorption step is performed multiple times, and the concentration of lithium in the desorption solution obtained at each step is compared to determine a shear desorption step up to a predetermined step, and the concentration of lithium salt in the medium at this time can be increased.

[0038] That is, a high-concentration medium can be used up to a certain desorption stage, and a relatively low-concentration medium can be used for the desorption stage after a certain reference point.

[0039] At this time, when calculating the lithium concentration in the desorption liquid, the lithium concentration contained in the medium may be excluded and the amount of lithium desorbed by the adsorbent may be used as the standard.

[0040] When a high-concentration medium is used in the desorption step, the lithium concentration in the resulting desorbed solution is affected not only by the lithium desorbed from the adsorbent, but also by the lithium concentration in the medium. In other words, the purpose is to consider only the effects of adsorption and desorption, excluding the influence of the medium.

[0041] Specifically, the shear desorption step can be maintained in a range where the difference in lithium concentration between the shear desorption solution and the rear desorption solution is 0.1 g / L or more.

[0042] The above medium may be an aqueous solution containing at least one of lithium chloride, lithium sulfate, and lithium borate.

[0043] The lithium concentration in the medium used in the above-mentioned pre-desorption step may be 0.2 g / L to 0.4 g / L, and the lithium concentration in the medium used in the above-mentioned post-desorption step may be 0.2 g / L to 0.1 g / L.

[0044] The method may further include a step of concentrating the entire desorption liquid obtained through the above-described front-end desorption step and the above-described rear-end desorption step.

[0045] The concentration efficiency of the above concentration step can be improved by more than 80%.

[0046] The concentration efficiency can be calculated as follows. Specifically, the efficiency of concentrating the final obtained desorption liquid is compared between a method in which the concentration of lithium salt in the medium of the pre-desorption step and the post-desorption step is controlled differently, as in one embodiment of the present invention, and a conventional method in which the concentration of lithium salt in the medium of these steps is maintained the same.

[0047] Specifically, it can be calculated as the ratio of the energy required for concentration when the concentration of lithium salt in the medium is the same, to the energy required when the method is the same as one example of the present invention.

[0048] When the desorption step is performed in the same manner as in one embodiment of the present invention, the lithium concentration in the final desorption liquid is high, so the amount of water that must be removed by concentration is significantly reduced, enabling efficient process design.

[0049] In a technology for recovering lithium by adsorption and desorption of lithium using an adsorbent, the present invention aims to provide a process for effectively recovering lithium by providing a more effective desorption technology.

[0050] Figure 1 shows lithium concentration data according to BV of a multi-stage desorption step according to one embodiment and a comparative example of the present invention.

[0051] Figure 2 shows the results of analyzing the actual lithium desorption amount according to BV according to examples and comparative examples.

[0052] Figure 3 shows the results of analyzing the lithium concentration in the actual desorption solution according to the desorption according to the BV according to the examples and comparative examples.

[0053] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention. The present invention is defined solely by the scope of the claims set forth below.

[0054] Example

[0055] A brine solution having the composition shown in Table 1 below was prepared.

[0056] Analysis ElementLi (g / L)Ca (g / L)Mg (g / L)B (g / L)K (g / L)Na (g / L)Content0.0720.01.40.36.548.0

[0057] The adsorbent column was 100 ml, and desorption was performed at a level of approximately 3 L. The front end was performed at ~6 BV (~0.6 L), and the back end at 6 to 30 BV (0.6 L to 3 L).

[0058] At this time, desorption was performed under the condition that the amount of medium performing one desorption step was defined as 1 Bed volume (BV).

[0059] The front-end detachment step was performed up to 6 BV, and the rear-end detachment step was performed from 7 BV to 30 BV.

[0060] At this time, detachment was performed under three conditions.

[0061] The first condition was that desorption was performed using distilled water in all steps.

[0062] The second condition was that desorption was performed using a lithium chloride aqueous solution with a concentration of 0.15 g / L in all steps.

[0063] The condition for the third time was that the concentration of lithium chloride in the medium used in the front desorption step was 0.3 g / L, and the concentration of lithium chloride in the medium used in the rear desorption step was 0.15 g / L.

[0064] Figure 1 shows lithium concentration data according to BV of a multi-stage desorption step according to one embodiment and a comparative example of the present invention.

[0065] In Figure 1, the dotted line is data obtained by performing desorption using distilled water, and the thick line is data obtained by using a medium with the same lithium concentration throughout the entire desorption step.

[0066] Additionally, the thin line represents example data where multiple desorption steps were performed, and it can be confirmed that the lithium concentration is high in most BVs.

[0067] However, since a high concentration medium was used initially, it can be seen that the lithium concentration in the desorption solution in most stages increased due to the influence of the lithium concentration in the medium.

[0068] Figure 2 shows the results of analyzing the actual lithium desorption amount according to BV according to examples and comparative examples.

[0069] At this time, the data in Fig. 2 is a value calculated by considering the amount of lithium in the medium, and it can be seen that in the initial BV, the amount of lithium desorbed from the adsorbent is actually less than in the comparative example.

[0070] It is assumed that this is because additional adsorption occurred along with desorption due to the influence of lithium in the medium, and that the lithium concentration in the medium acted as a factor interfering with desorption.

[0071] However, what should be noted in the results of Fig. 2 is that when the final rear-end detachment is achieved, the amount of detached lithium ultimately becomes the same.

[0072] Specifically, it can be confirmed that the example in which 0.3 g / L of lithium is initially added and 0.57 g / L is output has a smaller desorption amount than the comparative example in which 0.15 g / L is added and 0.47 g / L is output.

[0073] However, when desorption is performed up to approximately 30 BV, the total effective desorption amount is confirmed to be almost the same. It appears that the same amount of desorption can be expected within the range of approximately 18 BV.

[0074] That is, even if the media in the front and rear stages are used differently as in the example, the fact that all lithium in the adsorbent is ultimately desorbed remains unchanged.

[0075] Figure 3 shows the results of analyzing the lithium concentration in the actual desorption solution according to the desorption according to the BV according to the examples and comparative examples.

[0076] The results in Fig. 3, like Fig. 2, are values ​​that take into account the influence of lithium concentration in the medium.

[0077] As can be seen in Fig. 3, the lithium concentration in the desorption solution obtained in all desorption steps is confirmed to be high in the case of the example.

[0078] Specifically, looking at 28.8 BV, the lithium concentration in the desorption solution is 244 mg / L in the example and 212 mg / L in the comparative example. This is an 87% improvement in the effect of the example.

[0079] This means that the example is 87% more effective than the comparative example in terms of the amount of water that must be removed when concentrating to the same concentration.

[0080] That is, the examples and comparative examples ultimately desorb the same amount of lithium, but the examples yield a higher concentration of desorbed liquid.

[0081]

[0082] The present invention is not limited to the above-described embodiments, but can be manufactured in a variety of different forms. Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. An adsorption step of passing a lithium-containing solution through an aluminum-based adsorbent to obtain an adsorbent having lithium adsorbed thereon; and A desorption step of obtaining a lithium-containing desorption solution by passing a medium through the lithium-adsorbed adsorbent; A method for adsorption and desorption of lithium, wherein the medium used in the above desorption step contains a salt.

2. In paragraph 1, The above detachment step is performed multiple times, The above multiple detachment steps include a front detachment step and a rear detachment step, A method for lithium adsorption and desorption, wherein the concentrations of salt in the medium used in the pre-desorption step and the post-desorption step are different.

3. In paragraph 2, A method for adsorption and desorption of lithium, wherein the concentration of salt in the medium of the above-mentioned pre-desorption step is higher than the concentration of salt in the medium of the above-mentioned post-desorption step.

4. In paragraph 3, A method for adsorption and desorption of lithium, wherein the reference salt is a lithium salt at a concentration of salt in the above medium.

5. In paragraph 3, A lithium adsorption and desorption method comprising: determining the number of shear desorption steps by comparing the lithium concentration of the shear desorption solution obtained through the above-described shear desorption step with the lithium concentration of the post-desorption solution obtained through the above-described post-desorption step.

6. In paragraph 5, A method for adsorption and desorption of lithium, wherein when calculating the lithium concentration in the above-mentioned desorption solution, the lithium concentration contained in the medium is excluded, and the amount of lithium desorbed by the adsorbent is used as the standard.

7. In paragraph 5, A method for adsorption and desorption of lithium, wherein the pre-desorption step is maintained in a range where the difference in lithium concentration between the pre-desorption solution and the post-desorption solution is 0.1 g / L or more.

8. In paragraph 2, A method for adsorption and desorption of lithium, wherein the medium is an aqueous solution containing at least one of lithium chloride, lithium sulfate, and lithium borate.

9. In paragraph 2, A method for adsorption and desorption of lithium, wherein the lithium concentration in the medium used in the above-mentioned pre-desorption step is 0.2 g / L to 0.4 g / L, and the lithium concentration in the medium used in the above-mentioned post-desorption step is 0.2 g / L to 0.1 g / L.

10. In paragraph 2, A method for adsorption and desorption of lithium, further comprising a step of concentrating the entire desorption liquid obtained through the above-described pre-desorption step and the above-described post-desorption step.

11. In paragraph 10, A method for adsorption and desorption of lithium, wherein the concentration efficiency of the above concentration step is improved by 80% or more.

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