Method for adsorption / desorption of lithium

Abstract

A method for adsorption and desorption of lithium according to the present invention comprises: an adsorption step of passing a lithium-containing solution through an adsorbent loaded in a column to obtain a lithium-adsorbed adsorbent; a washing step of passing distilled water through the lithium-adsorbed adsorbent to remove impurities; and a desorption step of passing a medium through the lithium-adsorbed adsorbent to obtain a lithium-containing desorbed solution, wherein in the washing step, an integrated area value in a range of 0 to 2 BV of the volume of the distilled water in a graph of lithium concentration desorbed according to a volume of the distilled water satisfies 600 BV·mg / L or less.

Description

Lithium adsorption and desorption method

[0001] This application claims priority to Korean Patent Application No. 10-2024-0191149 filed on December 19, 2024, and all contents of said priority application are incorporated into this specification.

[0002] The present invention relates to a method for the adsorption and desorption of lithium.

[0003] Lithium-ion batteries are an essential component in small devices such as mobile phones and laptops, and recently, the demand for them is also increasing as a power source for hybrid and electric vehicles. Consequently, the demand for lithium, a key raw material for lithium-ion batteries, is also surging.

[0004] Lithium, a key material for such lithium secondary batteries, is generally extracted from minerals, seawater, brine, etc. However, the lithium content in the Earth's crust is only 0.006%, and because of its high reactivity, it is not found in nature in the form of pure metal; generally, it is extracted in the form of lithium compounds such as Li2CO3 and LiOH·H2O rather than in the form of pure metal.

[0005] In addition, although seawater is abundant globally, its lithium content is low at 0.17 mg / L, which results in low efficiency for lithium extraction and high production costs compared to other lithium sources.

[0006] The most common method for extracting lithium is to evaporate water from brine and then add carbonates to extract lithium in the form of lithium carbonate. However, to extract lithium carbonate by adding carbonates, the brine must be concentrated to an economically viable level before proceeding with the extraction process; consequently, there is a problem in that brine sources capable of improving the economic feasibility of lithium extraction are scarce worldwide.

[0007] Therefore, there is an urgent need to develop technologies that can economically and efficiently recover lithium from lithium-containing solutions. As one such method, selective adsorption and desorption technologies for lithium using adsorbents are being researched.

[0008] The present invention aims to provide a method for the adsorption and desorption of lithium that minimizes lithium loss during the washing process and effectively removes impurities.

[0009] The present invention relates to a method for the adsorption and desorption of lithium, comprising: an adsorption step of passing a lithium-containing solution through an adsorbent packed in a column to obtain an adsorbent on which lithium is adsorbed; a washing step of passing distilled water through the adsorbent on which lithium is adsorbed to remove impurities; and a desorption step of passing a medium through the adsorbent on which lithium is adsorbed to obtain a lithium-containing desorbent, wherein in the washing step, the integral area value in the volume range of the distilled water in a graph of the concentration of desorbed lithium according to the volume of the distilled water satisfies 600 BV·mg / L or less.

[0010] The method for adsorbing and desorbing lithium according to the present invention has the advantage of being able to delay the desorption of lithium from the adsorbent, reduce the lithium loss rate, and effectively separate residual impurities from the lithium-containing desorption solution and the surface of the adsorbent.

[0011] In addition, there is an advantage in that impurities in the lithium-containing desorption solution can be effectively reduced using distilled water without the need for a separate pretreatment solution.

[0012] Figures 1 to 7 show data representing the lithium concentration according to BV in the washing and detachment steps according to the examples and comparative examples.

[0013] 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, and the present invention is defined only by the scope of the claims set forth below.

[0014] In the present invention, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0015]

[0016] One aspect of the present invention relates to a method for the adsorption and desorption of lithium, comprising: an adsorption step of passing a lithium-containing solution through an adsorbent packed in a column to obtain an adsorbent on which lithium is adsorbed; a washing step of passing distilled water through the adsorbent on which lithium is adsorbed to remove impurities; and a desorption step of passing a medium through the adsorbent on which lithium is adsorbed to obtain a lithium-containing desorbent, wherein in the washing step, the value of the integrated area in the volume range of the distilled water in a graph of the concentration of desorbed lithium according to the volume of the distilled water satisfies 600 BV·mg / L or less.

[0017]

[0018] The method for adsorbing and desorbing lithium according to the present invention has the advantage of suppressing the loss of lithium that occurs during the washing process of a process for directly extracting lithium from brine or salt lakes using an adsorbent.

[0019] In addition, it has the advantage of effectively removing impurities using only distilled water without the need for a separate pretreatment solution.

[0020]

[0021] Adsorption step

[0022] The method for adsorbing and desorbing lithium according to the present invention comprises an adsorption step of passing a lithium-containing solution through an adsorbent packed in a column to obtain an adsorbent on which lithium has been adsorbed.

[0023] The above adsorption step refers to a step of adsorbing lithium from a lithium-containing solution. Specifically, the lithium-containing solution may be passed through an adsorbent packed in the column to adsorb lithium onto the adsorbent.

[0024]

[0025] In another embodiment of the present invention, the lithium concentration of the lithium-containing solution in the adsorption step may be 0.05 to 2.0 g / L. Specifically, the lithium concentration of the lithium-containing solution may be 0.05 to 1.8 g / L, and more specifically 0.1 to 1.5 g / L.

[0026] When the lithium concentration of the above lithium-containing solution satisfies the above range, lithium adsorption on the adsorbent is easy, resulting in excellent adsorption efficiency and the advantage of increasing economic efficiency by reducing the need to operate multiple adsorption columns.

[0027] In addition, since there is an advantage in increasing economic efficiency by reducing the time to reach the breakthrough point of the adsorbent and the need to operate multiple adsorption columns, it is desirable for the lithium concentration of the lithium-containing solution to satisfy the above range.

[0028]

[0029] The above adsorbent is intended to adsorb lithium dissolved in the above lithium-containing solution.

[0030] In another embodiment of the present invention, the adsorbent may be an aluminum-based adsorbent.

[0031] Specifically, the above adsorbent may include aluminum hydroxide and a lithium salt.

[0032] When using an aluminum-based adsorbent containing the above aluminum hydroxide and lithium salt, the adsorption amount of lithium dissolved in the lithium-containing solution is high, and since there is almost no loss of aluminum in the desorption step described later, the adsorbent has a long lifespan, thus providing the advantage of excellent economic efficiency in the lithium extraction process.

[0033] The above aluminum-based adsorbent may be a molded body comprising adsorbent powder and a binder.

[0034] The above-mentioned adsorbent powder may be, for example, an adsorbent powder containing aluminum hydroxide and a lithium salt. The advantages of using an adsorbent powder containing aluminum hydroxide and a lithium salt are the same as those described above.

[0035] The above binder is intended to manufacture the adsorbent powder into a molded body of a suitable shape and serves to bind the adsorbent powders together.

[0036] The binder may include, for example, at least one of polyvinyl chloride (PVC), polysulfone, and polyaniline. Specifically, it is preferable that the binder include polyvinyl chloride (PVC), which can provide excellent bonding strength between adsorbent powders.

[0037]

[0038] Meanwhile, the step of passing a lithium-containing solution through an aluminum-based adsorbent to adsorb lithium onto the aluminum-based adsorbent may include, for example, the reaction of the following reaction scheme 1.

[0039] [Reaction Equation 1]

[0040] (1-x)LiCl · 2Al(OH) 3· nH2O + xLiCl → LiCl · 2Al(OH) 3· nH2O

[0041]

[0042] Washing step

[0043] The method for adsorbing and desorbing lithium according to the present invention includes a washing step of removing impurities by passing distilled water through the aforementioned lithium adsorbent; wherein, in the washing step, the integral area value in the volume range of the distilled water is 600 BV·mg / L or less in the graph of the concentration of desorbed lithium according to the volume of the distilled water.

[0044] Specifically, in the washing step above, the integrated area value may be 550 or less, more specifically 510 or less.

[0045] Specifically, the integrated area value refers to the area of ​​the graph at the point when the amount of distilled water used is the concentration (mg / L) of lithium desorbed into the distilled water according to the amount of distilled water (BV).

[0046] For example, when the above distilled water is flowed up to 2 BV, the area of ​​the graph when the volume of the above distilled water is from 0 to 2 BV, in other words, the integrated area value may be 600 BV·mg / L or less. When the above distilled water is flowed up to 1 BV, it is the area of ​​the graph when the volume of the above distilled water is from 0 to 1 BV, and when the above distilled water is flowed up to 3 BV, it is the area of ​​the graph when the volume of the above distilled water is from 0 to 3 BV.

[0047] Specifically, the graph above can utilize the concentration graph of lithium that is desorbed into distilled water or a desorption solution according to the washing and desorption steps as shown in FIGS. 1 to 7.

[0048] Satisfying the above integrated area value means that the amount of lithium desorption in the washing section is 1 mg or less per 1 g of adsorbent, which means that lithium desorption is delayed during the washing step.

[0049] Therefore, in the present invention, by controlling the integrated area value, the phenomenon of lithium desorption occurring early in the washing step is suppressed, and impurities are effectively reduced. By delaying the desorption in the washing step, the lithium concentration in the desorption section described later can be increased.

[0050] Although it is not desired to be limited by theory, if the desorption delay effect does not occur, it is difficult to separate impurities and lithium; however, if the temperature and flow rate of the column are controlled to reduce the rate at which the distilled water diffuses into the interior of the adsorbent, the lithium desorption delay effect is excellent, allowing for the effective separation of lithium and impurities by effectively removing only the impurities present on the surface of the adsorbent, thereby reducing lithium loss.

[0051]

[0052] In one embodiment of the present invention, in the washing step; the flow rate of the distilled water may be 10 to 120 BV.

[0053] In another embodiment of the present invention, in the washing step; when the temperature of the column is 30°C or lower, specifically 25°C, the flow rate of the distilled water may be greater than 10 BV / h, preferably 20 to 120 BV / h, more preferably 30 to 120 BV / h.

[0054] In another embodiment of the present invention, in the washing step; when the temperature of the column is greater than 30°C and less than or equal to 40°C, specifically 40°C, the flow rate of the distilled water may be greater than 30 BV / h, preferably 40 to 120 BV / h, and more preferably 50 to 120 BV / h.

[0055] In another embodiment of the present invention, when the temperature of the adsorption / desorption column in the washing step is greater than 40°C and less than or equal to 60°C, specifically 60°C, the flow rate of the distilled water may be greater than 50 BV / h, preferably 60 to 120 BV / h, and more preferably 70 to 120 BV / h.

[0056] In another embodiment of the present invention, when the temperature of the column exceeds 60°C, the flow rate of the distilled water may be 60 BV / h or higher, and preferably 65 to 120 BV / h.

[0057]

[0058] It is desirable that the flow rate of the distilled water according to each temperature range satisfies the above range, as this has the effect of delaying desorption.

[0059]

[0060] The method for adsorbing and desorbing lithium according to the present invention has the advantage of effectively reducing impurities while suppressing the phenomenon of lithium being initially desorbed during the washing step by controlling the flow rate of distilled water according to temperature based on the filling volume of the adsorbent, specifically the adsorbent on which lithium is adsorbed.

[0061]

[0062] In the present invention, “bed volume (BV)” may refer to the volume of the adsorbent packed in the column.

[0063]

[0064] In another embodiment of the present invention, the washing step may satisfy Formula 1 below.

[0065] [Equation 1]

[0066] 0.9 ≤ A / B ≤ 10

[0067] In the above Equation 1,

[0068] A is the flow rate of distilled water (BV / h), and

[0069] B is the column temperature (°C).

[0070]

[0071] In another embodiment of the present invention, the washing step may satisfy Formula 2 below.

[0072] [Equation 2]

[0073] 1 ≤ A / B ≤ 5

[0074] In the above Equation 2,

[0075] A and B are as defined in Equation 1 above.

[0076]

[0077] Although it is not desired to be limited by theory, in the washing step described above, as the temperature of the column increases, lithium ions acquire a high diffusivity, and as the temperature of the column decreases, the diffusivity of lithium ions decreases. Therefore, when the temperature is high, the desorption of lithium ions adsorbed on the adsorbent to the outside of the adsorbent is promoted. When the column is at the same temperature, if the flow rate of distilled water increases, the contact time between the adsorbent and the washing solution—that is, the distilled water—is shortened. Consequently, the diffusivity of lithium in the adsorbent on which lithium ions are adsorbed decreases, allowing for effective washing of impurities outside the adsorbent while delaying the diffusion of lithium adsorbed inside, thereby obtaining a sufficient desorption delay effect.

[0078] In short, by controlling the flow rate of the distilled water and the temperature of the column together, the integrated area value can be achieved, and thereby a sufficient desorption delay effect can be obtained in the washing step, and a high concentration of lithium solution can be obtained in the lithium recovery section to the extent of the desorption delay.

[0079]

[0080] With respect to the total 100% by weight of lithium present in the adsorbent after the above adsorption step, the amount of lithium contained in the distilled water after passing through the adsorbent and washing with distilled water may be in the range of 0.1 to 30.0% by weight, and specifically, may be in the range of 1 to 8.0% by weight, 1.0 to 6.0% by weight, 1.0 to 4.0% by weight, or 1.0 to 2.5% by weight.

[0081] This means that the desorption of lithium adsorbed on the adsorbent in the above washing step is suppressed.

[0082]

[0083] Detachment step

[0084] The method for adsorbing and desorbing lithium according to the present invention comprises a desorption step of passing a medium through the aforementioned adsorbent on which lithium is adsorbed to obtain a lithium-containing desorbent.

[0085] Specifically, a lithium-containing desorbent can be obtained by passing a medium, such as distilled water or an aqueous solution containing a lithium salt, through the aluminum adsorbent on which the lithium is adsorbed.

[0086] At this time, the amount of medium passed through the aluminum adsorbent on which the lithium is adsorbed can be 10 to 50 BV, specifically 15 to 40 BV, and more specifically 15 to 30 BV, based on the bed volume (BV) of the adsorbent.

[0087]

[0088] In the total lithium-containing desorbent obtained by passing a medium through an adsorbent, most of the lithium adsorbed on the adsorbent must be desorbed so that the lithium concentration in the desorbent after 80 volume% of the medium has passed is 0.3 g / L or less, specifically 0.1 g / L or 0.05 g / L, so that it is possible to adsorb lithium again using the said adsorbent. Therefore, a step of passing an amount of medium within the above range through the aluminum adsorbent in which lithium is adsorbed may be necessary.

[0089] Lithium can be recovered through a desorption solution with a high lithium concentration obtained through the above desorption step, but is not limited thereto. Specifically, the lithium-containing desorption solution can be used in the process up to the step of passing through a medium of 10 BV after the washing step in which impurities are removed, and preferably, the lithium-containing desorption solution can be used up to the step of passing through a medium of 7 BV or 5 BV, but may vary depending on the shape of the desorption curve.

[0090] With respect to the total 100 weight% of lithium present in the adsorbent after the adsorption step, the amount of lithium obtained in the desorption step may be in the range of 50.0 to 99.9 weight%, and specifically, in the range of 70.0 to 90.0 weight%.

[0091]

[0092] In the case where the washing step according to the present invention is not included, the amount of lithium lost with respect to 100% by weight of the total lithium present in the adsorbent after the adsorption step may be in the range of 10.0 to 70.0% by weight, and specifically, may be in the range of 25.0 to 60.0% by weight or 30.0 to 50.0% by weight. The reason for such lithium loss is that a lithium-containing desorption solution containing a high concentration of impurities may be difficult to use in the lithium recovery process. It is preferable that the concentration of impurities (salts excluding lithium) be lower, and specifically, in the case of a lithium-containing desorption solution containing impurities (salts excluding lithium) at a concentration of 20 g / L, 15 g / L, or 10 g / L or less, the recovery rate of lithium hydroxide obtained after proceeding with the subsequent process described below may be excellent.

[0093]

[0094] The step of obtaining a lithium-containing desorbent by passing a medium through the above-mentioned aluminum adsorbent on which lithium is adsorbed may include, for example, the reaction of Reaction Scheme 2 below.

[0095] [Reaction Equation 2]

[0096] LiCl·2Al(OH)3·nH2O → (1-x)LiCl·2Al(OH)3·nH2O + xLiCl

[0097]

[0098] The medium used in the above desorption step may be an aqueous solution containing a lithium salt, specifically, the medium may be an aqueous solution containing lithium chloride. In this case, the concentration of lithium in the obtained desorption solution may be increased. This improvement in the lithium concentration in the desorption solution can reduce the load on the downstream concentration process.

[0099] Specifically, the lithium concentration in the medium may be in the range of 0.05 to 1.50 g / L, and more specifically, 0.10 to 1.00 g / L, 0.10 to 0.80 g / L, or 0.10 to 0.40 g / L.

[0100] If the lithium concentration in the medium satisfies the above range, it is desirable to suppress the phenomenon in which lithium (Li) contained in the aluminum adsorbent is lost and causes damage to the LDH (Layered Double Hydroxide) structure.

[0101] The concentration of lithium contained in the lithium-containing desorption solution obtained by the above method may be 0.1 g / L to 3.0 g / L, or 0.2 g / L to 3.0 g / L, and more specifically, 0.4 g / L to 2.5 g / L.

[0102] When the lithium concentration of the desorption solution is high, it implies 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 downstream process. In this case, the downstream process may refer to the concentration step.

[0103] A method for the adsorption and desorption of lithium according to one embodiment may further include a step of concentrating the total desorbed solution obtained through the desorption step.

[0104] Specifically, the concentration step may include a concentration process of the desorbent using reverse osmosis and electrodialysis, through which the target lithium concentration can be determined according to the characteristics of the intermediate to be extracted. If additional concentration is required beyond the above methods, the lithium concentration can be raised to the desired level through a concentration step using reduced pressure / evaporation.

[0105]

[0106] Preferred embodiments and comparative examples of the present invention are described below. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0107]

[0108] Examples and Comparative Examples

[0109] A brine solution with the composition shown in Table 1 below was prepared. Subsequently, Al-LDH [LiCl] 0-1 The adsorbent was passed through a [Al(OH)3]2 adsorbent. Afterward, the adsorbent was washed with distilled water (washing water) for 2 BV volumes according to temperature and flow rate conditions (see Table 2), and desorption was performed using a LiCl solution with a lithium concentration of 0.3 g / L for 28 BV volumes.

[0110]

[0111] Saline composition LiNaKCaB mg / L 360 44,000 16,500 30,400 390

[0112] Table 2 below shows the column temperature and distilled water (washing water) flow rate conditions during the washing step, and accordingly, lithium concentration data according to BV during the washing and desorption steps are shown in Figures 1 to 7, and the area where the volume of distilled water is in the range of 0 to 2 BV is shown in Table 2 below.

[0113]

[0114] (A) Wash water flow rate (BV / h) (B) Column temperature (°C) Area Formula 1 (A / B) Related Drawings Comparison Example 1 50 60 86 90.83°C 1 Comparison Example 2 30 40 60 40.75°C 2 Example 1 60 60 50 11°C 3 Example 2 75 60 45 11.25°C 4 Example 3 50 40 49 1.25°C 5 Example 4 30 25 49 61.2°C 6 Example 5 50 25 37 82°C 7

[0115] Referring to Figures 1 to 7, it can be seen that the loss rate decreases as the flow rate of distilled water increases and the temperature of the column decreases.

[0116] Specifically, in the case of the example, it can be seen that the detachment delay is excellent, so the phenomenon of lithium detaching from impurities in the initial washing section is suppressed.

[0117] On the other hand, in the case of Comparative Example 1, which was washed with a volume of 2 BV at the same temperature as Example 1 but with a relatively slow flow rate, it can be seen that there is no delay in desorption, and most of the lithium is desorbed along with impurities in the initial washing section.

[0118] Meanwhile, it can be seen that in the case of Comparative Example 2, which was washed with a volume of 2 BV at the same temperature as Example 3 but with a relatively slow flow rate, the detachment delay was not sufficient, resulting in a large amount of lithium loss.

[0119] Specifically, it can be seen that a lag phenomenon was observed starting from 60 BV / h at 60℃, and up to 50 BV / h at 40℃. In addition, it can be seen that a lag phenomenon was observed up to 30 BV / h or less at 25℃.

[0120]

[0121] The present invention is not limited to the above embodiments but can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the 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 adsorbent packed in a column to obtain an adsorbent on which lithium is adsorbed; A washing step of removing impurities by passing distilled water through the adsorbent on which the lithium is adsorbed; and A desorption step of obtaining a lithium-containing desorbent by passing a medium through the adsorbent on which the lithium is adsorbed; Includes, In the above washing step; A method for the adsorption and desorption of lithium satisfying that, in a graph of the concentration of desorbed lithium according to the volume of distilled water, the integral area value in the volume range of the distilled water is 600 BV·mg / L or less.

2. In Paragraph 1, A method for the adsorption and desorption of lithium, wherein the flow rate of the distilled water is 10 to 120 BV.

3. In Paragraph 1, A method for the adsorption and desorption of lithium, wherein the flow rate of the distilled water is greater than 10 BV / h when the temperature of the column is 30℃ or lower.

4. In Paragraph 1, A method for the adsorption and desorption of lithium, wherein the temperature of the column is greater than 30℃ and less than or equal to 40℃, and the flow rate of the distilled water is greater than 30 BV / h.

5. In Paragraph 1, A method for the adsorption and desorption of lithium, wherein the temperature of the column is greater than 40℃ and less than or equal to 60℃, and the flow rate of the distilled water is greater than 50 BV / h.

6. In Paragraph 1, A method for the adsorption and desorption of lithium, wherein when the temperature of the column exceeds 60℃, the flow rate of the distilled water is 60 BV / h or higher.

7. In Paragraph 1, The above washing step; is a method for the adsorption and desorption of lithium satisfying Formula 1 below: [Equation 1] 0.9 ≤ A / B ≤ 10 In the above Equation 1, A is the flow rate of distilled water (BV / h), and B is the column temperature (°C).

8. In Paragraph 1, A method for the adsorption and desorption of lithium, wherein the lithium concentration of the lithium-containing solution in the above adsorption step is 0.05 to 2.0 g / L.

9. In Paragraph 1, A method for the adsorption and desorption of lithium, wherein the lithium concentration of the medium used in the above desorption step is 0.05 to 1.50 g / L.

10. In Paragraph 1, A method for the adsorption and desorption of lithium in which the above-mentioned adsorbent is an aluminum-based adsorbent.

11. In Paragraph 1, A method for the adsorption and desorption of lithium, further comprising the step of concentrating the total desorbed solution obtained through the above desorption step.

Images