Lithium recovery system for recovering lithium from lithium-containing solution

Abstract

The present invention relates to a continuous circulation-type lithium recovery system comprising a plurality of columns, the system comprising: an adsorption unit comprising 1 to N adsorption columns for adsorbing lithium from a lithium-containing solution; and a desorption unit comprising 1 to M desorption columns for desorbing the lithium from the adsorbate that has passed through the adsorption unit. (Here, N is a value ranging from 2 to 5, and M is a value ranging from 2 to 10)

Description

Lithium recovery system for recovering lithium from lithium-containing solution

[0001] The present invention relates to a lithium recovery system, and more particularly, to a system for effectively recovering lithium from a lithium-containing solution.

[0002] Lithium secondary batteries are essential components in small devices such as cell phones and laptops, and demand for lithium secondary batteries is increasing as a power source for hybrid and electric vehicles.

[0003] Lithium, the core material of these lithium secondary batteries, is generally extracted from minerals, seawater, and salt water.

[0004] However, the Earth's crust contains only 0.006% lithium, and due to its high reactivity, it is not found in nature in pure metallic form. Therefore, extracting it in pure metallic form requires a process that requires significant energy consumption, is costly, and poses environmental problems.

[0005] In addition, although seawater is abundant worldwide, its lithium content is low at 0.17 mg / L, which makes lithium extraction efficiency low and its production cost high compared to other lithium raw materials.

[0006] The most common method for extracting lithium is to evaporate the water from brine and then add a carbonate to extract lithium carbonate. However, to extract lithium carbonate using carbonate, the brine must be concentrated to an economically viable level before the lithium extraction process can begin. However, brine capable of improving the economic feasibility of lithium extraction is limited worldwide.

[0007] Therefore, the development of technologies capable of recovering lithium even from raw materials with low lithium content is urgent. Furthermore, interest is growing in processes that recover lithium through adsorption and desorption processes, even from raw materials with low lithium content.

[0008] However, the conventional single or serial adsorption and desorption process has the problem that it takes a considerable amount of time to recover lithium, and the structure of the adsorbent collapses, reducing the recovery rate of lithium.

[0009] A lithium recovery system according to one embodiment of the present invention provides a lithium recovery system with high process efficiency by preventing structural collapse of an adsorbent and shortening the time for lithium recovery.

[0010] In one embodiment, the lithium recovery system relates to a continuous circulating lithium recovery system comprising a plurality of columns, the system including an adsorption unit comprising 1 to N adsorption columns for adsorbing lithium from a lithium-containing solution, and a desorption unit comprising 1 to M desorption columns for desorbing lithium from the adsorbate passing through the adsorption unit.

[0011] (However, N means a value greater than or equal to 2 and less than or equal to 5, and M means a value greater than or equal to 2 and less than or equal to 10)

[0012] In one embodiment, the plurality of adsorption columns and the plurality of desorption columns of the adsorption unit and the desorption unit are connected in parallel, and the lithium-containing solution can be continuously circulated through the plurality of columns. In one embodiment, the adsorption unit can be injected with an aluminum-based adsorbent.

[0013] In one embodiment, the structure of lithium aluminum intercalate (Layered Double Hydroxide, LDH) in the lithium-containing solution can be maintained in the adsorption unit. In one embodiment, when the lithium-containing solution in the first adsorption column satisfies the adsorption target value, the first adsorption column becomes the Mth desorption column of the desorption unit, and the Nth adsorption column can be controlled as the N-1th column.

[0014] In one embodiment, when the desorption liquid in the first desorption column satisfies the desorption target, the first desorption column becomes the Nth adsorption column in the adsorption unit, and the Mth desorption column can be controlled as the M-1th column. In one embodiment, after the lithium-containing solution in the first adsorption column satisfies the desorption target, the first adsorption column can be controlled as the Mth desorption column after undergoing a washing process.

[0015] In one embodiment, the initial lithium (Li) concentration of the lithium-containing solution may be greater than or equal to 75 mg / L. In one embodiment, the desorption solution may pass through the first to M-1 desorption columns to absorb lithium and enter the M desorption column.

[0016] In one embodiment, the desorption liquid may increase the concentration of Li in the M desorption column. In one embodiment, when the desorption liquid in the first desorption column satisfies the desorption target value, the first adsorption column in the adsorption unit may be controlled as the M desorption column.

[0017] In one embodiment, the desorption unit may have a desorption amount of the desorption solution of 10 to 20 BV. In one embodiment, the lithium concentration of the desorption unit may be 0.10 to 0.30 g / L. In one embodiment, the adsorption target value may be a case where at least one of the cases where the pH of the lithium-containing solution is 4.5 to 9.0, the electrical conductivity of the lithium desorption solution is 1 mS / cm to 10 mS / cm, and the Li concentration of the lithium desorption solution is 0.1 g / L to 3 g / L is satisfied.

[0018] A lithium recovery system according to one embodiment of the present invention includes a plurality of columns, and the plurality of columns perform continuous circulation, thereby preventing structural collapse of an adsorbent and shortening the time for lithium recovery, thereby providing a lithium recovery system with high process efficiency.

[0019] FIG. 1A and FIG. 1B are schematic diagrams of a driving method of a lithium recovery system according to one embodiment of the present invention.

[0020] Figures 2a and 2b show the Li concentration after adsorption according to the bed volume (BV) in the adsorption section.

[0021] Figure 3 shows the lithium concentration according to the BV of the desorption solution and the desorption flow rate.

[0022] Figures 4a and 4b show Li concentration versus desorption amount according to the number of desorption columns according to examples and comparative examples of the present invention.

[0023] 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.

[0024] 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.

[0025] In addition, the size and thickness of each component shown in the drawing are arbitrarily shown for convenience of explanation, so the present invention is not necessarily limited to what is shown.

[0026] 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.

[0027] To clearly illustrate various layers and regions in the drawings, the thicknesses are enlarged. Similar parts are designated by the same drawing reference numerals throughout the specification. When an element, such as a layer, film, region, or plate, is said to be "on top of" another element, this includes not only the case where it is "directly on top of" the other element, but also the case where there are other elements in between. Conversely, when an element is said to be "directly on top of" another element, it means that there are no other elements in between.

[0028] Then, a method for recovering lithium from a lithium-containing solution according to one embodiment is described below.

[0029] According to one embodiment of the present invention, a lithium recovery system may be a continuous circulation lithium recovery system comprising a plurality of columns. Specifically, the system may include an adsorption unit comprising a plurality of adsorption columns and a desorption unit comprising a plurality of desorption columns. The plurality of adsorption columns and the plurality of desorption columns of the adsorption unit and the desorption unit may be connected in parallel. By connecting the plurality of adsorption columns and the plurality of desorption columns in parallel, it can be confirmed that the process time is shortened and the effect is excellent compared to when the same amount of solution is injected into a single column.

[0030] Specifically, the fact that the above columns are connected in parallel means that when a plurality of adsorption columns are in the adsorption stage, another plurality of columns perform desorption, thereby performing a continuous adsorption-desorption process.

[0031] In one embodiment, the lithium-containing solution may be a lithium-containing substance, such as brine extracted from a salt lake. For example, it may be brine extracted from South America or artificially manufactured brine. The lithium-containing solution may be supplied to a separately provided container and then supplied to the adsorption unit, or may be supplied directly to the adsorption unit.

[0032] In one embodiment, the adsorption unit may include a plurality of adsorption columns for adsorbing lithium from a lithium-containing solution. The adsorption unit may include an adsorbent for extracting lithium from the lithium-containing solution. In one embodiment, the adsorbent may include an aluminum-based adsorbent. For example, the adsorbent may be [LiX] 0-1 It may be a [Al(OH)3]2 (lithium aluminum intercalate, LDH) compound. The adsorbent may be such that a solution containing lithium is injected into the adsorbent, and LiCl inside the adsorbent is released to the outside, thereby allowing lithium to be adsorbed.

[0033] In one embodiment, the adsorption unit may include 1 to N adsorption columns. In this case, N may have a value of 2 or more and 5 or less. N may be 2 or more and 4 or less, more specifically, 2 or more and 3 or less. Since the adsorption unit includes 1 to N adsorption columns, adsorption is performed while maintaining the lithium aluminum intercalate structure of the adsorbent included in the adsorption unit, thereby increasing the concentration of Li.

[0034] If the number of adsorption columns, N, of the above adsorption unit exceeds the upper limit, there is a problem that the number of columns for lithium production increases, requiring excessive facility investment. If N exceeds the lower limit, there is a problem that lithium is not sufficiently recovered or the adsorption capacity of the adsorbent to adsorb lithium is not sufficiently utilized, resulting in a deterioration in productivity.

[0035] In one embodiment, the desorption unit can desorb lithium from the adsorbate that has passed through the adsorption unit. Specifically, the desorption unit can recover lithium by controlling the desorption of lithium adsorbed on the adsorbate. More specifically, the desorption unit can desorb lithium by introducing a low-concentration lithium solution and allowing the lithium adsorbed on the adsorbent to diffuse into the low-concentration lithium solution, and can recover the desorbed lithium by concentrating, refining, and converting it into lithium carbonate or lithium hydroxide.

[0036] In one embodiment, the desorption unit may include 1 to M desorption columns for desorbing lithium from the adsorbate that has passed through the adsorption unit. The adsorbate may be an adsorbent having lithium adsorbed thereon. In this case, M may be 2 or more and 10 or less. Specifically, M may be 2 or more and 5 or less, and more specifically, 2 or more and 4 or less. Since the desorption unit includes a plurality of desorption columns within the aforementioned range, the time required for lithium desorption can be reduced, thereby increasing the efficiency of the process.

[0037] In one embodiment, if M, the number of desorption columns of the desorption unit, exceeds the upper limit, there is a problem that the number of lithium desorption columns increases, requiring excessive facility investment and worsening economic feasibility. If M exceeds the lower limit, there is a problem that sufficient lithium desorption is not achieved, and the adsorption capacity decreases in the step of adsorbing lithium to the column after desorption, resulting in a deterioration in the productivity of the entire system.

[0038] In one embodiment, when the lithium-containing solution in the first adsorption column satisfies the adsorption target, the first adsorption column becomes the M-th desorption column of the desorption unit, and the N-th adsorption column can be controlled as the N-1-th column. Specifically, when the lithium-containing solution in the first adsorption column satisfies the adsorption target, the first adsorption column is controlled by a separately connected member, such as a valve, to change from an adsorption column to a desorption column.

[0039] Specifically, when the lithium-containing solution in the first adsorption column achieves the adsorption target value, the column may be changed to a desorption column to desorb lithium from the adsorbed adsorbate, and continuous operation may be performed.

[0040] In one embodiment, the adsorption target value may be satisfied when at least one of the following is satisfied: when the pH of the lithium-containing solution is 4.5 to 9.0, when the electrical conductivity of the lithium desorption solution is 1 mS / cm to 10 mS / cm, and when the Li concentration of the lithium desorption solution is 0.1 g / L to 3 g / L.

[0041] Specifically, when the pH of the lithium-containing solution is outside the upper limit of the above-mentioned range, or when the pH of the lithium-containing solution is outside the lower limit of the above-mentioned range, there is a problem in that the LDH structure of the adsorbent is not maintained.

[0042] If the electrical conductivity of the lithium desorption solution exceeds the upper limit of the aforementioned range, there is a problem that the adsorbed lithium may not be desorbed or the desorption rate may become very slow. If the electrical conductivity of the lithium-containing solution exceeds the lower limit of the aforementioned range, there is a problem that the LDH structure of the adsorbent may collapse.

[0043] In one embodiment, if the Li concentration of the desorption-containing solution exceeds the upper limit of the aforementioned range, there is a problem that the adsorbed lithium is not desorbed or the desorption rate is excessively reduced. If the Li concentration of the lithium-containing solution exceeds the lower limit of the aforementioned range, there is a problem that the LDH structure of the adsorbent may collapse.

[0044] In this way, when at least one of the pH, electrical conductivity, and Li concentration of the lithium-containing solution satisfies the aforementioned range, the adsorption target value is determined to be completed and the first adsorption column is controlled to be changed to a desorption column. At this time, the first adsorption column that has reached the adsorption target value is changed to an M-th desorption column, and the second adsorption column, the third adsorption column, ..., the N-th adsorption column are controlled to be changed to the first adsorption column, the second adsorption column, ..., the N-1-th adsorption column.

[0045] In one embodiment, when the lithium-containing solution in the first adsorption column achieves the desorption target, the first adsorption column may be controlled as the M desorption column after undergoing a washing process. The washing process may be applied equally to the desorption column.

[0046] In one embodiment, when the desorption liquid in the first desorption column satisfies the desorption target, the first desorption column becomes the Nth adsorption column in the adsorption unit, and the Mth desorption column can be controlled as the M-1th column. Specifically, when the desorption liquid in the first desorption column satisfies the desorption target, the first desorption column is controlled by a separately connected member, such as a valve, to change from a desorption column to an adsorption column.

[0047] Specifically, when the desorption liquid in the first desorption column has achieved the desorption target, the column may be changed to an adsorption column to perform re-adsorption with the desorbed substance, and continuous operation may be performed.

[0048] In this way, when the desorption liquid has achieved the desorption target, it is determined that the desorption has been performed at an appropriate level, and in order to further increase the lithium concentration in the desorption liquid, the first desorption column is controlled to be changed to an adsorption column. At this time, the first desorption column that has reached the desorption target is changed to an Nth adsorption column, and the second desorption column, the third desorption column, ..., the Mth desorption column are controlled to be changed to the first desorption column, the second desorption column, ..., the N-1th desorption column.

[0049] Accordingly, the first adsorption column that has reached the adsorption target is changed to the M desorption column, and the first adsorption column that has reached the desorption target is changed to the N adsorption column, and as the above-described process is performed continuously, lithium can be recovered in a short period of time, thereby increasing the efficiency of the process.

[0050] In one embodiment, the desorption liquid can pass through the first to M-1 desorption columns and absorb lithium. In one embodiment, the desorption liquid passing through the first to M-1 desorption columns can increase the concentration of Li in the M-1 desorption column. A detailed description thereof is provided below with reference to FIGS. 1A and 1B.

[0051] FIG. 1A and FIG. 1B are schematic diagrams of a driving method of a lithium recovery system according to one embodiment of the present invention.

[0052] Figure 1a illustrates, in a lithium recovery system according to one embodiment of the present invention, how adsorbate passing through an adsorption unit enters a plurality of desorption columns of a desorption unit. For example, if the desorption unit is composed of first, second, and third desorption columns, desorption water containing LiCl may sequentially pass through the first and second desorption columns, absorb a portion of the Li present in the first and second desorption columns, and then enter the third desorption column.

[0053] FIG. 1b illustrates a lithium recovery system according to an embodiment of the present invention, when desorption is completed in the first desorption column, the columns that performed the roles of the second desorption column and the third desorption column in FIG. 1a perform the roles of the first desorption column and the second desorption column. Thereafter, the first adsorption column, in which adsorption is completed in the adsorption section, can be controlled to perform the role of the third desorption column in FIG. 1a to increase the Li concentration of the desorption water. In this way, by having the adsorption and desorption columns continuously perform adsorption and desorption of lithium, the lithium recovery rate can be increased, the process time can be shortened, and the efficiency can be improved.

[0054] In one embodiment, the desorption unit may have a desorption amount of the desorption liquid of 10 to 40 BV (Bed Volume). Specifically, the desorption volume may be 10 to 20 BV. The BV may refer to the packing volume of the adsorption / desorption column. When the desorption amount of the desorption liquid satisfies the above-mentioned range, there is an advantage in that the effect of speeding up the process is realized by including a plurality of desorption columns.

[0055] If the desorption amount of the above-mentioned desorption solution exceeds the upper limit of the above-mentioned range, the desorption time is excessively long, which causes a problem of deterioration in lithium extraction productivity. If the desorption amount of the above-mentioned desorption solution exceeds the lower limit of the above-mentioned range, there is a problem of not being able to desorb sufficient lithium, and thus not being able to adsorb the separated lithium in the post-desorption adsorption step.

[0056] In one embodiment, the initial lithium (Li) concentration of the lithium-containing solution may be 75 mg / L or more. In one embodiment, the lithium concentration of the desorption portion may be 0.15 to 3 g / L. Specifically, the lithium concentration of the desorption portion may be 0.15 to 2 g / L, and more specifically, the lithium concentration of the desorption portion may be 0.12 to 0.18 g / L. If the lithium concentration of the desorption portion is outside the lower limit of the aforementioned range, there is a problem of the structure of the adsorbent collapsing.

[0057] In one embodiment, the reactants that have passed through the aforementioned desorption unit may be discharged through a discharge unit (not shown) or returned to the aforementioned adsorption unit for reuse. Thus, the lithium recovery system according to one embodiment of the present invention can operate in a manner in which lithium ion adsorption and desorption are performed continuously.

[0058]

[0059] Hereinafter, preferred embodiments of the present invention and experimental examples thereof will be described. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0060]

[0061] Experimental example

[0062] <Comparative Example>

[0063] Preparation of lithium-containing solutions

[0064] A brine having a composition as shown in Table 1 below was prepared.

[0065] ClassificationLiNaKBClContent(g / L)0.7278.546.511.01Bal.

[0066]

[0067] Adsorption part

[0068] The above lithium-containing solution was introduced into the first and second adsorption columns, which were connected in parallel and filled with adsorbent powder, at a flow rate of 0.1 BV / min, and an adsorption process was performed. In the adsorption section, multiple adsorption columns, specifically two, were configured as a parallel system.

[0069] Figure 2b shows the Li concentration after adsorption according to the bed volume (BV) in the adsorption section.

[0070] At this time, the adsorbent powder is [LiX] 0-1[Al(OH)3]2 (lithium aluminum intercalate, LDH) compound was used. The X is a positive anion, such as (Cl-, SO42-, PO42-, etc.).

[0071] The above adsorbent powder comprises aluminum hydroxide having a two-dimensional layered structure, which facilitates the insertion of anions between the layers, and positively charged lithium cations diffuse into the hexagonal cavities formed within the two-dimensional layered structure, which easily accommodate the size of lithium.

[0072] Specifically, LiCl within the adsorbent powder can escape from the structure at a certain rate without causing a change in the structure of the adsorbent powder. The adsorbent powder from which the LiCl has escaped has a high salt concentration, and when it comes into contact with a lithium solution containing LiCl, the space from which the LiCl has escaped is quickly filled.

[0073] When the adsorbent from which the LiCl has been released comes into contact with a lithium solution containing LiCl and has a high salt concentration to fill the vacant site from which the LiCl has been released, the degree to which the vacant site is filled is higher as the LiCl concentration of the lithium solution is higher and the salt concentration is higher.

[0074] When the above adsorbent comes into contact with water having a low salt concentration and a low LiCl concentration, LiCl inside the adsorbent is released to the outside, and the degree to which LiCl is released to the outside is inversely proportional to the salt concentration and the LiCl concentration. At this time, when coming into contact with water having extremely low salt concentration and LiCl concentration, the lithium aluminum intercalate structure of the adsorbent may collapse as the LiCl of the adsorbent is excessively released. When the adsorbent with the collapsed structure comes into contact with a high-concentration LiCl solution, it absorbs LiCl and is regenerated into the lithium aluminum intercalate structure of the adsorbent, and it can be confirmed that this speed is slower than the speed at which the lithium aluminum intercalate structure of the normal structure absorbs LiCl.

[0075] In this way, in order to increase the speed of the brine (raw brine) fed into the adsorption column section with the adsorbent added, the speed at which LiCl in the brine is absorbed by the adsorbent must be increased. A high speed can be expected when the structure of the adsorbent is maintained, but a high speed cannot be expected when the LiCl in the adsorbent is excessively extracted and the structure is deformed. Therefore, the adsorbent in the adsorption section must maintain the lithium aluminum intercalate structure and secure an appropriate amount of empty space for LiCl.

[0076]

[0077] In the adsorption section, a single adsorption column, specifically one, was configured.

[0078] When LiCl is absorbed into the lithium aluminum intercalate structure in the adsorption unit, after absorbing about 60% of the maximum capacity of LiCl, some of the LiCl in the brine is not absorbed, and as the amount of LiCl absorbed increases, the amount of LiCl remaining in the brine increases. Thus, in order to increase the lithium recovery rate, the remaining LiCl must be injected into another column in the adsorption unit to absorb the remaining LiCl. For this purpose, as in the above embodiment, two or more parallel systems are required. Even if a parallel system is configured, when the lithium aluminum intercalate structure of the adsorbent is deformed, the rate of recovering the remaining LiCl is significantly reduced.

[0079]

[0080] <Example>

[0081] Preparation of lithium-containing solutions

[0082] A brine having a composition as shown in Table 2 below was prepared.

[0083] DistinctionLiNaKBCl Content (g / L)0.373240.5Bal.

[0084]

[0085] Adsorption part

[0086] The above lithium-containing solution was injected into the first and second adsorption columns connected in parallel and filled with adsorbent powder at a flow rate of 0.1 BV / min, and the adsorption process was performed. At this time, the adsorbent powder was [LiX] 0-1 [Al(OH)3]2 (lithium aluminum intercalate, LDH) compound was used. X is a positive anion, such as (Cl-, SO42-, PO42-, etc.). Figure 2a shows the Li concentration after adsorption according to the bed volume (BV) in the adsorption section.

[0087] At this time, the adsorbent powder is [LiX] 0-1 [Al(OH)3]2 (lithium aluminum intercalate, LDH) compound was used. The X is a positive anion, such as (Cl-, SO42-, PO42-, etc.).

[0088] The above adsorbent powder comprises aluminum hydroxide having a two-dimensional layered structure, which facilitates the insertion of anions between the layers, and positively charged lithium cations diffuse into the hexagonal cavities formed within the two-dimensional layered structure, which easily accommodate the size of lithium.

[0089] Specifically, LiCl within the adsorbent powder can escape from the structure at a certain rate without causing a change in the structure of the adsorbent powder. The adsorbent powder from which the LiCl has escaped has a high salt concentration, and when it comes into contact with a lithium solution containing LiCl, the space from which the LiCl has escaped is quickly filled.

[0090] When the adsorbent from which the LiCl has been released comes into contact with a lithium solution containing LiCl and has a high salt concentration to fill the vacant site from which the LiCl has been released, the degree to which the vacant site is filled is higher as the LiCl concentration of the lithium solution is higher and the salt concentration is higher.

[0091] When the above adsorbent comes into contact with water having a low salt concentration and a low LiCl concentration, LiCl inside the adsorbent is released to the outside, and the degree to which LiCl is released to the outside is inversely proportional to the salt concentration and the LiCl concentration. At this time, when coming into contact with water having extremely low salt concentration and LiCl concentration, the lithium aluminum intercalate structure of the adsorbent may collapse as the LiCl of the adsorbent is excessively released. When the adsorbent with the collapsed structure comes into contact with a high-concentration LiCl solution, it absorbs LiCl and is regenerated into the lithium aluminum intercalate structure of the adsorbent, and it can be confirmed that this speed is slower than the speed at which the lithium aluminum intercalate structure of the normal structure absorbs LiCl.

[0092] In this way, in order to increase the speed of the brine (raw brine) fed into the adsorption column section with the adsorbent added, the speed at which LiCl in the brine is absorbed by the adsorbent must be increased. A high speed can be expected when the structure of the adsorbent is maintained, but a high speed cannot be expected when the LiCl in the adsorbent is excessively extracted and the structure is deformed. Therefore, the adsorbent in the adsorption section must maintain the lithium aluminum intercalate structure and secure an appropriate amount of empty space for LiCl.

[0093] In the adsorption section, a single adsorption column, specifically one, was configured.

[0094] When LiCl is absorbed into the lithium aluminum intercalate structure in the adsorption unit, after absorbing about 60% of the maximum capacity of LiCl, some of the LiCl in the brine is not absorbed, and as the amount of LiCl absorbed increases, the amount of LiCl remaining in the brine increases. Thus, in order to increase the lithium recovery rate, the remaining LiCl must be injected into another column in the adsorption unit to absorb the remaining LiCl. For this purpose, as in the above embodiment, two or more parallel systems are required. Even if a parallel system is configured, when the lithium aluminum intercalate structure of the adsorbent is deformed, the rate of recovering the remaining LiCl is significantly reduced.

[0095] In this way, when multiple adsorption columns are arranged in parallel in the adsorption section as in the example, deformation of the lithium aluminum intercalate structure of the adsorbent can be minimized while simultaneously increasing the recovery rate of residual Li. In contrast, when a single adsorption column is used as in the comparative example, deformation of the lithium aluminum intercalate structure can occur and the problem of a decrease in the recovery rate of residual LiCl can occur.

[0096]

[0097] Detachable part

[0098] In order to maintain the lithium aluminum intercalate structure of the adsorbent and allow LiCl to escape, a process of sequentially lowering the LiCl concentration of the water in contact with the adsorbent is required. According to the experimental results, this process is performed by injecting about 30 BV of desorbed water with a lithium concentration of about 150 ppm into the adsorbent column, and the concentration of the extracted LiCl solution sequentially decreases according to the amount injected, and eventually reaches 150 ppm, which is the same concentration as the injected desorbed water.

[0099] Figure 3 shows the lithium concentration according to the BV of the desorption solution and the desorption flow rate.

[0100] Figure 3 shows the lithium concentration according to the BV of the desorption solution in a single column. It was confirmed that the lithium concentration was similar even when the desorption solution speed was different in a single column. Through this, it was confirmed that the desorption solution injection speed is not a major factor in controlling the lithium concentration. However, if the desorption solution injection speed is excessively high, there is a problem of excessive pressure being applied to the adsorbent in the column, so the injection speed cannot be excessively increased, and it was confirmed that the maximum injection speed is approximately 90 BV / hr.

[0101] <Example>

[0102] The number of detachment columns of the detachment unit was arranged in a parallel system in multiple numbers, specifically three.

[0103] <Comparative Example>

[0104] The number of detachment columns in the detachment section is set to a single unit, specifically 1 unit.

[0105]

[0106] Looking at the examples and comparative examples, the process of returning the lithium aluminum intercalate structure in the desorption section to a state suitable for adsorption requires sequentially lowering LiCl around the adsorbent, and at this time, the desorption water introduced requires a flow rate of approximately 30 BV, so it was confirmed that the desorption time can be drastically shortened by arranging multiple desorption columns in the desorption section and arranging them in parallel.

[0107] Specifically, as in the example, when a desorption unit including three desorption columns is configured in parallel, a flow rate of about 10 BV is required per column, so the time is shortened to 1 / 3 compared to a single desorption column, and it was confirmed that as the number of desorption columns increases to n, the time is shortened to 1 / n. However, if the number of desorption columns increases excessively, the volume of the adsorbent within the configuration increases, which may have a negative impact on productivity, so it was confirmed that including three desorption columns is suitable.

[0108] Figures 4a and 4b show Li concentration versus desorption amount according to the number of desorption columns according to examples and comparative examples of the present invention.

[0109] Figures 4a and 4b show the Li concentration according to the desorption amount (BV) of the example with three desorption columns and the comparative example with one, respectively. Referring to Figures 4a and 4b, the solution that completed adsorption in the adsorption section was washed by adding NaCl at 0 to 2 BV, and then 0.15 g / L of LiCl was added to compare the lithium concentration according to the desorption amount.

[0110] Tables 3 and 4 below show the desorption amount of examples and comparative examples, specifically the lithium concentration according to the filling volume.

[0111] Desorption volume (BV) 3.317 3.95 14.90 26.80 410.60 815.68 Li concentration (g / L) 0.65 90.48 30.43 90.39 50.33 240.28 09

[0112] Desorption Volume (BV) 0.144 0.43 30.72 21.01 1.58 82.16 52.29 42.8 13.45 55.26 111.19 521.51 53 6.99 5 Li Concentration (g / L) 0.03 0.04 80.11 0.12 0.11 30.12 20.17 0.32 80.5 130.39 30.23 60.17 9 0.16

[0113] Looking at the above FIGS. 4a and 4b and Tables 3 and 4, about 15 mg of Li was required per 1 BV of desorption water based on the example, and the example including three desorption columns was sufficient with about 16 BV, but the comparative example including one desorption column required about 37 BV. Accordingly, it was confirmed that the example including multiple desorption columns, specifically about 3, reduced the process time of the desorption section by about 57% compared to the comparative example including a single desorption column, thereby increasing the process efficiency.

[0114]

[0115] 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. A continuous circulation lithium recovery system including a plurality of columns, An adsorption unit comprising 1 to N adsorption columns for adsorbing lithium from a lithium-containing solution; A lithium recovery system comprising a desorption unit including 1 to M desorption columns for desorbing lithium from an adsorbate that has passed through the adsorption unit. (However, N means a value greater than or equal to 2 and less than or equal to 5, and M means a value greater than or equal to 2 and less than or equal to 10) 2. In paragraph 1, The plurality of adsorption columns and the plurality of desorption columns of the above adsorption unit and the above desorption unit are connected in parallel, The above lithium-containing solution is a lithium recovery system that continuously circulates through multiple columns.

3. In paragraph 1, The above adsorption unit is a lithium recovery system into which an aluminum-based adsorbent is introduced.

4. In paragraph 1, A lithium recovery system in which the structure of lithium aluminum intercalate (Layered Double Hydroxide, LDH) in the lithium-containing solution is maintained in the above-mentioned adsorption / desorption section.

5. In paragraph 1, When the lithium-containing solution in the first adsorption column satisfies the adsorption target value, The above first adsorption column becomes the M desorption column of the desorption section, The above Nth adsorption column is a lithium recovery system controlled by the Nth-1 column.

6. In paragraph 1, If the desorption liquid in the first desorption column satisfies the desorption target, The above first desorption column becomes the Nth adsorption column in the adsorption section, The above M desorption column is a lithium recovery system controlled by the M-1 column.

7. In paragraph 1, After the lithium-containing solution in the first adsorption column satisfies the desorption target value, The above first adsorption column is a lithium recovery system controlled by the M desorption column after going through a washing process.

8. In paragraph 1, A lithium recovery system wherein the initial lithium (Li) concentration of the lithium-containing solution is 75 mg / L or more.

9. In paragraph 7, A lithium recovery system in which the desorption liquid passes through the first to M-1 desorption columns, absorbs lithium, and enters the M desorption column.

10. In paragraph 7, The desorption solution is a lithium recovery system that increases the concentration of Li in the M desorption column.

11. In clause 10, If the desorption liquid in the first desorption column satisfies the desorption target, A lithium recovery system in which the first adsorption column in the above adsorption section is controlled by the M desorption column.

12. In paragraph 1, The above-mentioned desorption unit is a lithium recovery system having a desorption amount of a desorption liquid of 10 to 40 BV.

13. In paragraph 12, A lithium recovery system wherein the lithium concentration of the above-mentioned detachment section is 0.10 to 3.0 g / L.

14. In paragraph 5, The above adsorption target value is, When the pH of the lithium-containing solution is 4.5 to 9, When the electrical conductivity of the lithium-containing solution is 1 to 10 mS / cm, and A lithium recovery system defining a case where at least one of the cases where the Li concentration of the lithium-containing solution is 0.1 to 3 g / L is satisfied.

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