Method for preparing lithium compound

Abstract

Provided is a method for preparing a lithium compound, the method comprising the steps of: extracting Li from saline through direct lithium extraction to obtain a LiCl-containing saline-treated solution; separating lithium ions from the LiCl-containing saline-treated solution and producing a LiOH aqueous solution containing the separated lithium ions, wherein the LiOH aqueous solution is produced by introducing the LiCl-containing saline-treated solution into a device provided with an ion exchange membrane and a bipolar membrane, and the LiOH aqueous solution and a HCl aqueous solution are produced in the device together according to chemical equation 1; obtaining Li2CO3 by using the LiOH aqueous solution and carbon dioxide; and mixing a Li2CO3 extraction filtrate remaining after obtaining Li2CO3 with the HCl aqueous solution produced in the device, thereby removing carbonate ions (CO3 2-), and then recycling as a saline supply source. <Chemical equation 1> LiCl + H2O → HCl + LiOH

Description

Method for manufacturing lithium compounds

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

[0002] The global electric vehicle market is projected to grow from 2.3 million units in 2019 to 21.9 million units in 2030. Battery performance is also continuously improving through increased capacity and longer lifespan. Regarding cathode active materials for secondary batteries, the market share of high-energy-density High-Ni batteries is also predicted to rise to 76% by 2030. Consequently, the demand for lithium hydroxide, a raw material for High-Ni cathode active materials, is also expected to increase.

[0003] Lithium, a raw material for lithium-ion batteries, has traditionally been produced by extracting lithium carbonate from salt lakes, reacting it with lime to obtain a lithium hydroxide solution, and then crystallizing it. However, the lime process generates limestone as a byproduct, and the operation of kilns to recycle the limestone produces large amounts of carbon dioxide, posing a problem of being unenvironmentally friendly.

[0004] The objective of the present invention is to provide a method for producing lithium compounds from brine in an environmentally friendly manner, which can simplify the process of removing impurities while reducing process costs.

[0005] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0006] In one embodiment of the present invention, the method comprises the steps of: obtaining a LiCl-containing brine treatment solution by extracting Li from brine by a direct lithium extraction method; separating lithium ions from the LiCl-containing brine treatment solution and generating an aqueous LiOH solution containing the separated lithium ions; the step of generating the aqueous LiOH solution comprises introducing the LiCl-containing brine treatment solution into a device equipped with an ion exchange membrane and a bipolar membrane to generate the aqueous LiOH solution, wherein the aqueous LiOH solution and an aqueous HCl solution are generated together in the device according to the following chemical formula 1, and obtaining Li2CO3 using the aqueous LiOH solution and carbon dioxide; and mixing the aqueous HCl solution generated in the device with the Li2CO3 extraction filtrate remaining after obtaining Li2CO3 to obtain carbonate ions (CO3 2- A method for manufacturing a lithium compound that is recycled as a brine source after removing ) is provided.

[0007] <Chemical Formula 1>

[0008] LiCl + H2O → HCl + LiOH

[0009]

[0010] In one embodiment of the present invention, the method comprises the steps of: obtaining a LiCl-containing brine treatment solution by extracting Li from brine by a direct lithium extraction method; concentrating the LiCl-containing brine treatment solution; purifying the concentrated LiCl-containing brine treatment solution by removing divalent cation impurities from the concentrated LiCl-containing brine treatment solution; separating lithium ions from the purified LiCl-containing brine treatment solution and producing an aqueous LiOH solution containing the separated lithium ions; primary crystallizing the produced aqueous LiOH solution to obtain crude lithium hydroxide; secondary crystallizing the crude lithium hydroxide to obtain a lithium hydroxide product; and reacting the remaining amount of LiOH-containing liquid generated while producing the lithium hydroxide product with carbon dioxide to obtain Li2CO3. and a step of removing divalent cation impurities by introducing at least a portion of the obtained Li2CO3 into the concentrated LiCl-containing brine treatment solution; wherein the step of generating the LiOH aqueous solution comprises introducing the purified LiCl-containing brine treatment solution into a device equipped with an ion exchange membrane and a bipolar membrane to generate the LiOH aqueous solution, wherein the LiOH aqueous solution is generated together with an HCl aqueous solution according to the following Chemical Formula 1 in the device, and the remaining amount of the LiOH-containing filtrate is reacted with carbon dioxide to extract Li2CO3, and the HCl aqueous solution generated in the device is mixed with the Li2CO3 extract filtrate to obtain carbonate ions (CO3 2- We intend to provide a method for manufacturing a lithium compound that is recycled as a brine source after removing )

[0011] <Chemical Formula 1>

[0012] LiCl + H2O → HCl + LiOH

[0013]

[0014] The above direct lithium extraction method may be a method utilizing any one selected from the group consisting of ion exchange, ion adsorption, solvent extraction, and combinations thereof.

[0015] The above LiCl-containing brine treatment solution can be concentrated by at least one method selected from the group consisting of reverse osmosis, electrodialysis, MVR forced concentration, and combinations thereof.

[0016] LiOH can be added to the above concentrated LiCl-containing brine treatment solution to precipitate and remove the above divalent cation impurities.

[0017] At least a portion of the crude lithium hydroxide obtained by the above primary crystallization can be used as LiOH to remove the above divalent cation impurities.

[0018] The method for manufacturing the above lithium compound may include a first purification step of purifying the concentrated LiCl-containing brine treatment solution, and then further include a second purification step of removing impurities using an ion exchange resin.

[0019] The LiOH aqueous solution can be produced by including lithium ions separated by the ion exchange membrane from the purified LiCl-containing brine treatment solution and hydroxide ions generated by the decomposition of water by electrodialysis in the bipolar membrane.

[0020] The concentration of the above HCl aqueous solution may be 0.1 to 20 wt%.

[0021] The method for manufacturing the above lithium compound may use the above aqueous HCl solution as a washing solution to regenerate the ion exchange resin used in the above secondary purification step; use the above aqueous HCl solution as a washing solution to regenerate the reverse osmosis membrane used in the step of concentrating the above LiCl-containing brine treatment solution; or obtain the above LiCl-containing brine treatment solution by a direct lithium extraction method using ion exchange with an ion exchange membrane, and use the above aqueous HCl solution as a washing solution to regenerate the ion exchange resin used in the above direct lithium extraction method.

[0022] The method for producing the above lithium compound can produce the LiOH aqueous solution by introducing the purified LiCl-containing brine treatment solution obtained therefrom directly into a device equipped with the ion exchange membrane and bipolar membrane, without performing any additional purification steps other than the step of purifying the above concentrated LiCl-containing brine treatment solution; and a secondary purification step of removing impurities using an ion exchange resin following the step of purifying the above concentrated LiCl-containing brine treatment solution.

[0023] According to the method for manufacturing the above lithium compound, the process for removing impurities can be simplified, the amount of auxiliary raw materials used to remove impurities can be reduced, and auxiliary raw materials can be procured within the process. In addition, the method for manufacturing the above lithium compound can recycle the Li2CO3 extract filtrate as a brine source by utilizing a low-concentration aqueous HCl solution generated as a byproduct.

[0024] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0025] Figure 1 is a flowchart of a method for manufacturing the above lithium compound.

[0026] Figure 2 schematically shows an exemplary structure of a bipolar electrodialysis device.

[0027] FIG. 3 is a process configuration diagram according to one example of a method for manufacturing the lithium compound.

[0028] FIG. 4 is a diagram showing a part of the process according to one example of a method for manufacturing the lithium compound.

[0029] Figures 5 to 13 show the results of analyzing the process conditions in Figure 4 and the content of Li and other elements contained in the brine.

[0030] Figures 14 to 16 are tables showing the results of simulating the behavior of a process to obtain an aqueous LiOH solution by converting LiCl to LiOH using a bipolar electrodialysis device (BPED).

[0031] FIG. 17 is a diagram of a process for obtaining the LiCl-containing brine treatment solution from the direct lithium extraction (DLE) desorbent, purifying it, introducing it into a bipolar electrodialysis (BPED) device, assuming the composition of the basic solution of the bipolar electrodialysis (BPED) device, and then performing a primary crystallization step, a Li2CO3 extraction step, and a step of removing carbonate ions from the Li2CO3 extraction filtrate using an aqueous HCl solution.

[0032] Figures 18 to 29 show the results of analyzing the composition at the step according to the process diagram of Figure 17.

[0033] Figure 30 is a graph showing that carbonate ions in a solution change into carbon dioxide and CO2 depending on pH.

[0034] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0035] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0036] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0037] In this specification, lithium, sulfur, magnesium, calcium, sodium, potassium, etc., may be in a form that exists in raw materials, extracts, or precipitates, and are collectively referred to as types of elements without being limited to a specific form, such as metal atoms, atoms, ions, or salts, and when distinction is necessary, they may be understood as being in a state that exists according to the laws of nature.

[0038] In one embodiment of the present invention:

[0039] A step of obtaining a LiCl-containing brine treatment solution by extracting Li from brine by a direct lithium extraction method;

[0040] A step of separating lithium ions from the above LiCl-containing brine treatment solution and producing an aqueous LiOH solution containing the separated lithium ions;

[0041] The step of generating the above LiOH aqueous solution comprises introducing the above LiCl-containing brine treatment solution into a device equipped with an ion exchange membrane and a bipolar membrane to generate the above LiOH aqueous solution, and in the device, generating the above LiOH aqueous solution and the above HCl aqueous solution together according to the following Chemical Formula 1, and obtaining Li2CO3 using the above LiOH aqueous solution and carbon dioxide; and

[0042] By mixing the aqueous HCl solution generated in the above device with the Li2CO3 extract remaining after obtaining the above Li2CO3, carbonate ions (CO3 2- A method for manufacturing a lithium compound that is recycled as a brine source after removing ) is provided.

[0043] <Chemical Formula 1>

[0044] LiCl + H2O → HCl + LiOH

[0045]

[0046] In one embodiment of the present invention,

[0047] A step of obtaining a LiCl-containing brine treatment solution by extracting Li from brine by a direct lithium extraction method;

[0048] A step of concentrating the above LiCl-containing brine treatment solution;

[0049] A step of purifying the concentrated LiCl-containing brine treatment solution by removing divalent cation impurities from the concentrated LiCl-containing brine treatment solution;

[0050] A step of separating lithium ions from the purified LiCl-containing brine treatment solution and producing an aqueous LiOH solution containing the separated lithium ions;

[0051] A step of obtaining crude lithium hydroxide by first crystallizing the above-mentioned aqueous LiOH solution;

[0052] A step of obtaining a lithium hydroxide product by secondary crystallizing the above crude lithium hydroxide;

[0053] A step of obtaining Li2CO3 by reacting the remaining amount of LiOH-containing liquid generated while producing the above lithium hydroxide product with carbon dioxide; and

[0054] The method comprises the step of adding at least a portion of the obtained Li2CO3 to the concentrated LiCl-containing brine treatment solution to remove divalent cation impurities.

[0055] The step of generating the above LiOH aqueous solution involves introducing the purified LiCl-containing brine treatment solution into a device equipped with an ion exchange membrane and a bipolar membrane to generate the above LiOH aqueous solution, and in the device, the above LiOH aqueous solution is generated together with the HCl aqueous solution according to the following Chemical Formula 1, and

[0056] The Li2CO3 extract filtrate, obtained by reacting the remaining amount of LiOH-containing filtrate with carbon dioxide to extract Li2CO3, is mixed with an aqueous HCl solution generated by the above device to obtain carbonate ions (CO3 2- A method for manufacturing a lithium compound that is recycled as a brine source after removing ) is provided.

[0057] <Chemical Formula 1>

[0058] LiCl + H2O → HCl + LiOH

[0059]

[0060] Figure 1 is a process flow diagram of a method for manufacturing the above lithium compound.

[0061] The lithium compound obtained by the method for manufacturing the above lithium compound may be lithium hydroxide and / or lithium carbonate.

[0062] The method for manufacturing the above lithium compound can simplify the impurity removal process in subsequent processes because it uses a LiCl-containing brine treatment solution obtained by a direct lithium extraction method. The method for manufacturing the above lithium compound can perform a step of purifying the concentrated LiCl-containing brine treatment solution by removing divalent cation impurities, and then directly produce an aqueous LiOH solution from the concentrated LiCl-containing brine treatment solution. In this way, since the method for manufacturing the above lithium compound produces it by directly converting LiCl into LiOH after performing a purification process to remove divalent cation impurities, it does not generate large amounts of intermediate materials such as Li3PO4, Li2CO3, Li2SO4, etc., and can reduce the burden of processes such as precipitation and solid-liquid separation required to remove large amounts of precipitated intermediate materials. If large amounts of intermediate materials precipitate, the burden of processes such as precipitation and solid-liquid separation required to remove them increases. The method for manufacturing the above lithium compound has the advantage of reducing the process burden for removing intermediate materials that precipitate in large quantities, as the impurity removal process is simplified.

[0063] Direct Lithium Extraction (DLE) is a method for directly extracting lithium ions from brine. Direct lithium extraction can be performed using an adsorption method that adsorbs and desorbs LiCl molecules, an ion exchange method that adsorbs and desorbs lithium ions by ion exchange, a solvent extraction method that adsorbs or exchanges lithium ions using a solvent, or a method using a permeable membrane. The above adsorption method has the advantage of being able to extract lithium without acidic or basic auxiliary materials.

[0064] In one embodiment, the direct lithium extraction method may be a method for extracting lithium ions by utilizing any one selected from the group consisting of adsorption methods, ion exchange methods, solvent extraction methods, and combinations thereof.

[0065] A large amount of impurities can be effectively removed from brine by the direct lithium extraction method. The LiCl-containing brine treatment solution obtained by the above direct lithium extraction method can, for example, remove impurities by more than 99 wt% and secure a Li recovery rate of more than 95 wt%.

[0066] Next, the step of concentrating the above LiCl-containing brine treatment solution is performed.

[0067] For example, the LiCl-containing brine treatment solution can be obtained by adsorbing LiCl from brine using the adsorption method among direct lithium extraction methods, and then desorbing the adsorbed LiCl into fresh water. The LiCl-containing brine treatment solution obtained in this way has a very low concentration of about 500 to 700 mg / L.

[0068] In one embodiment, the LiCl-containing brine treatment solution can be concentrated to a concentration of 5 g / L to 15 g / L. The LiCl-containing brine treatment solution concentrated to the above numerical range has a concentration suitable for proceeding with the subsequent step of generating an aqueous LiOH solution. For example, the LiCl-containing brine treatment solution concentrated to the above numerical range is suitable for generating an aqueous LiOH solution by introducing it into a device equipped with an ion exchange membrane and a bipolar membrane.

[0069] In one embodiment, the LiCl-containing brine treatment solution can be concentrated by at least one method selected from the group consisting of reverse osmosis, electrodialysis, MVR forced concentration, and combinations thereof.

[0070] When producing the above-mentioned concentrated LiCl-containing brine treatment solution, for example, by reverse osmosis (RO), the purified water produced together can be supplied to places requiring fresh water within the process. For example, it can be used as fresh water to desorb lithium ions in the aforementioned direct lithium extraction method.

[0071] Next, a step is performed to purify the concentrated LiCl-containing brine treatment solution by removing divalent cation impurities from the concentrated LiCl-containing brine treatment solution.

[0072] The above divalent cation impurities may include, for example, ions such as Mg and Ca.

[0073] The step of purifying the above concentrated LiCl-containing brine treatment solution may be a chemical purification process in which auxiliary materials are added to precipitate and remove the above divalent cation impurities.

[0074] In one embodiment, during the step of purifying the concentrated LiCl-containing brine treatment solution, the pH can be adjusted to 10.5 or higher.

[0075] By adjusting the pH of the above concentrated LiCl-containing brine treatment solution to 10.5 or higher and adding an auxiliary raw material having anion, the solubility of the salt generated together with ions such as Mg and Ca is lowered, causing it to precipitate and be removed.

[0076] In one embodiment, the method for manufacturing the lithium compound may use Li2CO3 and / or LiOH instead of Na2CO3 or Ca(OH)2 as the auxiliary raw material.

[0077] As previously described, the method for manufacturing the above lithium compound utilizes the LiCl-containing brine treatment solution, which already reduces the concentration of impurities; therefore, it is possible to use Li2CO3 and / or LiOH as auxiliary raw materials instead of Na2CO3 or Ca(OH)2. This is because, when the impurity concentration is high, using Li2CO3 and / or LiOH as auxiliary raw materials results in the consumption of large amounts of expensive process intermediates, leading to a negative side effect of reduced economic feasibility. If only Ca is present as an impurity, it is possible to purify the impurity into the form of CaCO3 by adding only Li2CO3. Furthermore, if it is desired to remove impurities such as Mg and Mn that require precipitation at a high pH, ​​LiOH can be used to precipitate and remove them while adjusting the pH.

[0078] Since a large amount of impurities are removed in advance by the direct lithium extraction method for the above-mentioned lithium compound, the amount of Li2CO3 and / or LiOH that can be added as auxiliary materials may be low. Therefore, the method for manufacturing the above-mentioned lithium compound has the advantage of lowering process costs by reducing the amount of auxiliary materials such as Li2CO3 and / or LiOH used.

[0079] The method for manufacturing the above lithium compound has the advantage of minimizing unnecessary precipitates, such as CaCO3, without increasing the Na content, because it uses Li2CO3 and / or LiOH instead of Na2CO3 or Ca(OH)2 as the auxiliary raw material. In the subsequent process, if the Na content is high during the step of generating the LiOH aqueous solution, current efficiency may decrease. Therefore, the method for manufacturing the above lithium compound is a method that improves efficiency during the step of generating the LiOH aqueous solution.

[0080] In one embodiment, Li2CO3 can be added to the concentrated LiCl-containing brine treatment solution to precipitate and remove the divalent cation impurities.

[0081] In one embodiment, LiOH can be added to the concentrated LiCl-containing brine treatment solution to precipitate and remove the divalent cation impurities.

[0082] As previously mentioned, the Li2CO3 used as the auxiliary raw material may be obtained from the residual LiOH-containing liquid generated while producing the lithium hydroxide product. Additionally, the LiOH used as the auxiliary raw material may also be at least a portion of the crude lithium hydroxide obtained by the primary crystallization. That is, the method for manufacturing the lithium compound can have the advantage of not requiring separate external supply of auxiliary raw materials, as the Li2CO3 and / or LiOH used as auxiliary raw materials can be procured within the process.

[0083] In one embodiment, at least a portion of the crude lithium hydroxide obtained by the primary crystallization can be used as LiOH introduced to remove the divalent cation impurities.

[0084] The method for manufacturing the above lithium compound may include a first purification step of purifying the above concentrated LiCl-containing brine treatment solution and a second purification step of removing impurities using an ion exchange resin.

[0085] The above second purification step is a step of purifying trace residual divalent cation impurities using an ion exchange resin. Specifically, in the above second purification step, the surface of the ion exchange resin is treated with a LiOH solution to allow Li ions to attach, and then Ca, Mg, etc. in the concentrated LiCl-containing brine treatment solution are ion-exchanged and attached to the ion exchange resin, while the Li ions can be released into the concentrated LiCl-containing brine treatment solution.

[0086] Next, the step of separating lithium ions from the purified LiCl-containing brine treatment solution and producing an aqueous LiOH solution containing the separated lithium ions is performed.

[0087] Specifically, the step of generating the LiOH aqueous solution can be performed by introducing the purified LiCl-containing brine treatment solution into a device equipped with an ion exchange membrane and a bipolar membrane to generate the LiOH aqueous solution.

[0088] For example, the above step can be performed using a bipolar electrodialysis device as a device equipped with the ion exchange membrane and the bipolar membrane.

[0089] Figure 2 schematically shows an exemplary structure of the above device.

[0090] Specifically, the device comprises: an anode (1), a first bipolar membrane (3), an anion-selective ion exchange membrane (4), a cation-selective ion exchange membrane (5), a second bipolar membrane (6) and a cathode (2) in sequence; an acidic solution compartment (11) formed between the first bipolar membrane (3) and the anion-selective ion exchange membrane (4) and in which an acidic solution is generated; a basic solution compartment (12) formed between the second bipolar membrane (6) and the cation-selective ion exchange membrane (5) and in which a basic solution is generated; and a salt solution compartment (13) formed between the anion-selective ion exchange membrane (4) and the cation-selective ion exchange membrane (5).

[0091] The purified LiCl-containing brine treatment solution (10) can be introduced into the salt solution compartment (13). Water (90) is introduced into the acidic solution compartment (11) and the basic solution compartment (12). Electrode solution (80) is introduced between the anode (1) and the first bipolar membrane (3) and between the cathode (2) and the second bipolar membrane (6). The electrode solution (80) may be water or an aqueous solution.

[0092] When the above-mentioned purified LiCl-containing brine treatment solution (10) is introduced, lithium ions (Li) in the above-mentioned purified LiCl-containing brine treatment solution + ) passes through the cation-selective ion exchange membrane (5) and chloride ions (Cl - ) passes through the anion-selective ion exchange membrane (4), and the desalinated LiCl-containing brine treatment solution (10') is discharged from the salt solution compartment (13).

[0093] Lithium ions (Li) that have passed through the above anion-selective ion exchange membrane (4) + ) and hydroxide ions (OH) formed from water by electrodialysis in the second bipolar membrane (6) - An aqueous LiOH solution (30) formed including ) is discharged from the basic solution compartment (12).

[0094] When voltage is applied to the positive electrode (1) and the negative electrode (2), water is converted into hydrogen ions (H₂) by electrodialysis in the first bipolar membrane (3) and the second bipolar membrane (6). + ) and hydroxide ions (OH - It is decomposed into ) and hydrogen ions (H) into the acidic solution compartment (11) by electrostatic attraction. + ) moves, and hydroxide ions (OH) move to the basic solution compartment (12). - ) will move.

[0095] In one embodiment, lithium ions (Li) separated from the purified LiCl-containing brine treatment solution (10) by the ion exchange membrane. + ) and hydroxide ions (OH) generated by the decomposition of water by electrodialysis in the bipolar membrane - The LiOH aqueous solution can be produced within the basic solution compartment (12), including ). The LiOH aqueous solution (30) produced in this way is discharged from the basic solution compartment (12).

[0096] Chloride ions (Cl) that have passed through the anion-selective ion exchange membrane (4) from the purified LiCl-containing brine treatment solution (10) - ) and hydrogen ions (H) formed from water by electrodialysis in the first bipolar membrane (3) + An aqueous HCl solution (20) formed including ) is discharged from the acidic solution compartment (11) as a byproduct.

[0097] The reaction in the device in which an aqueous LiOH solution (30) is discharged from the basic solution compartment (12) and an aqueous HCl solution (20) is discharged from the acidic solution compartment (11) can be represented by the following chemical formula 1. That is, in the device, the aqueous LiOH solution is produced together with the aqueous HCl solution by the following chemical formula 1.

[0098] <Chemical Formula 1>

[0099] LiCl + H2O → HCl + LiOH

[0100]

[0101] The above HCl aqueous solution (20) can be discharged at a low concentration. For example, the concentration of the above HCl aqueous solution may be 0.1 to 20 wt%, specifically 1 to 15 wt%, and this may be changed depending on the operating conditions.

[0102] When the above HCl aqueous solution (20) is discharged at a low concentration, the above HCl aqueous solution (20) can be used as a washing solution to regenerate the ion exchange resin used in the secondary purification step of the above concentrated LiCl-containing brine treatment solution. In addition, when the above HCl aqueous solution (20) is discharged at a high concentration, it can be mixed with water appropriately and diluted for use.

[0103] Since the above HCl aqueous solution (20) is of low concentration, the above LiCl-containing brine treatment solution can be concentrated by reverse osmosis and then the above HCl aqueous solution (20) can be used as a cleaning solution for the reverse osmosis (RO) membrane used in the reverse osmosis process.

[0104] Since the above HCl aqueous solution (20) is of low concentration, when the above LiCl-containing brine treatment solution is obtained by the direct lithium extraction method by ion exchange using an ion exchange membrane, the above HCl aqueous solution (20) can be used as a washing solution to regenerate the ion exchange resin used in the above direct lithium extraction method.

[0105] Thus, the method for manufacturing the lithium compound has the advantage of being able to utilize the low-concentration aqueous HCl solution. Although it is difficult to concentrate the low-concentration aqueous HCl solution to a high concentration, the low-concentration aqueous HCl solution can be recycled as a washing solution within the various processes described above.

[0106] Since the method for manufacturing the above lithium compound effectively removes a large amount of impurities from the brine by the direct lithium extraction method, the step of purifying the concentrated LiCl-containing brine treatment solution is performed as a first purification step, and optionally, a second purification step is performed using an ion exchange resin following the first purification step to remove impurities; after removing impurities through a simple chemical purification process, it is possible to produce the LiOH aqueous solution by directly introducing the purified LiCl-containing brine treatment solution obtained in the purification step into a device equipped with the ion exchange membrane and bipolar membrane, while reducing excessive process burdens such as precipitation processes and solid-liquid separation processes for removing intermediate materials that precipitate in large amounts, such as Li3PO4, Li2CO3, Li2SO4, etc.

[0107] Next, the step of obtaining crude lithium hydroxide by first crystallizing the above-mentioned aqueous LiOH solution can be performed.

[0108] The above primary crystallization step can, for example, primary crystallize LiOH by concentrating the obtained LiOH aqueous solution through an evaporation concentration process.

[0109] As previously stated, a portion of the crude lithium hydroxide obtained above can be added as an auxiliary material in the step of purifying it by removing the divalent cation impurities. Since impurities are effectively removed from the brine by the direct lithium extraction method, the crude lithium hydroxide can be used as an auxiliary material instead of, for example, Na2CO3 or Ca(OH)2, thereby preventing an increase in impurities caused by the auxiliary material, for example, an increase in Na impurities, and minimizing unnecessary precipitates such as CaCO3. In addition, since the crude lithium hydroxide produced within the process is used directly in the process, there is an advantage in that there is no need to separately supply external auxiliary materials.

[0110] The above-mentioned crude lithium hydroxide can be obtained as a low-quality product with low purity. Since the low-quality crude lithium hydroxide is used as the above-mentioned auxiliary raw material, the cost burden can be reduced.

[0111] Next, a step of obtaining a lithium hydroxide product by secondary crystallizing the crude lithium hydroxide can be performed. In the secondary crystallization step, impurities can be further purified by redissolving using condensate. By performing the secondary crystallization step, high-quality or high-purity lithium hydroxide can be obtained.

[0112] Li2CO3 can be obtained by secondarily crystallizing the above crude lithium hydroxide to produce a lithium hydroxide product and using the remaining amount of LiOH-containing liquid generated.

[0113] Specifically, Li2CO3 can be obtained by reacting the remaining amount of LiOH-containing filtrate with carbon dioxide. In this way, by obtaining Li2CO3, Li ions can be further recovered from the remaining amount of LiOH-containing filtrate. That is, the process of obtaining Li2CO3 from the remaining amount of LiOH-containing filtrate can have significance as a process for recovering and utilizing Li from the waste solution generated during crystallization.

[0114] As previously described, in one embodiment, the obtained Li2CO3 can be introduced as an auxiliary material in the step of purifying it by removing the divalent cation impurities. Since impurities are effectively removed from the brine by the direct lithium extraction method, the obtained Li2CO3 can be used as an auxiliary material instead of, for example, Na2CO3 or Ca(OH)2, thereby preventing an increase in impurities caused by the auxiliary material, for example, an increase in Na impurities, and minimizing unnecessary precipitates such as CaCO3. In addition, since the obtained Li2CO3 produced within the process is used directly in the process, there is an advantage in that there is no need to separately supply external auxiliary materials.

[0115] The Li2CO3 extract filtrate, obtained by reacting the above-mentioned remaining LiOH-containing filtrate with carbon dioxide to extract Li2CO3, has a Li concentration similar to that of brine and can therefore be recycled as brine. However, the above-mentioned Li2CO3 extract filtrate contains a large amount of carbonate ions (CO3 2- Because ) is present, in order to recycle it as brine, carbonate ions (CO3 2- ) must be removed. This is because carbonate ions can be trapped within the structure of Al-based adsorbents, causing problems that shorten the lifespan of the adsorbent.

[0116] Since most carbonate ions change into CO2 and escape as a gas when the pH is lowered to the slightly acidic range, acid is added to the above Li2CO3 extract solution to [remove] carbonate ions (CO3 2- ) can be removed. Figure 30 is a graph showing that carbonate ions in the solution change into carbon dioxide and CO2 depending on pH.

[0117] In the above Li2CO3 extract filtrate, carbonate ions (CO3 2- To remove ), an aqueous HCl solution generated as a byproduct in the above device can be used.

[0118] As mentioned above, the above HCl aqueous solution is of low concentration, so carbonate ions (CO3) in the above Li2CO3 extract filtrate 2- It may be suitable for removing ).

[0119] In one embodiment, the step of generating the LiOH aqueous solution involves introducing the purified LiCl-containing brine treatment solution into a device equipped with an ion exchange membrane and a bipolar membrane to generate the LiOH aqueous solution, wherein the LiOH aqueous solution is generated together with an HCl aqueous solution according to the following Chemical Formula 1 in the device, and the HCl aqueous solution generated in the device is mixed with the Li2CO3 extract filtrate to produce carbonate ions (CO3 2- ) can be removed.

[0120] <Chemical Formula 1>

[0121] LiCl + H2O → HCl + LiOH

[0122]

[0123] As mentioned above, carbonate ions (CO3 2- The Li2CO3 extract filtrate from which ) has been removed can be recycled by being mixed into the brine and introduced into the process of extracting Li from brine using the direct lithium extraction method described above. Carbonate ions (CO3 2- The above Li2CO3 extract filtrate from which ) has been removed exhibits a Li concentration similar to that of brine, so it is suitable for use as a brine source.

[0124] In addition, the method for manufacturing the lithium compound has the advantage of utilizing the low-concentration aqueous HCl solution by using the Li2CO3 extract filtrate as a brine source. Although it is difficult to concentrate the low-concentration aqueous HCl solution to a high concentration, carbonate ions (CO3) from the Li2CO3 extract filtrate 2- In the process of removing ) and recycling it as a brine source, a low concentration of HCl aqueous solution can also be recycled within the process.

[0125] FIG. 3 is a process configuration diagram of a method for manufacturing the lithium compound according to one embodiment.

[0126] Examples and comparative examples of the present invention are described below. The following examples are merely embodiments of the present invention, and the present invention is not limited to the following examples.

[0127]

[0128] (Example)

[0129] Example 1

[0130] In the method for manufacturing the above lithium compound, the process up to obtaining a LiCl-containing brine treatment solution by the direct lithium extraction method, purifying it, and introducing it into a bipolar electrodialysis (BPED) device was simulated using a process simulation program according to the process diagram shown in Fig. 4, and the process conditions at each process step and the content of Li and other elements contained in the brine were analyzed. Figs. 5 to 13 show the results of analyzing the process conditions and the content of Li and other elements contained in the brine according to the process diagram in Fig. 4.

[0131] Following Fig. 4, a process of converting LiCl into LiOH using the bipolar electrodialysis (BPED) device of Fig. 2 to obtain an aqueous LiOH solution was simulated.

[0132] As shown in Fig. 4, the LiCl-containing brine treatment solution was obtained using the direct lithium extraction method (DLE) desorption solution, purified, and then fed into a bipolar electrodialysis (BPED) device, and the results of simulating the behavior are shown in Figs. 14 to 16.

[0133] Figure 17 shows the composition of the basic solution of the bipolar electrodialysis device (BPED) as assumed using Figures 14 to 16, and the composition of the subsequent first crystallization step, Li2CO3 extraction step, and the step of removing carbonate ions from the Li2CO3 extraction filtrate using an aqueous HCl solution as simulated. Figure 17 is a schematic diagram of a process in which the LiCl-containing brine treatment solution is obtained from the desorbent of the direct lithium extraction method (DLE), purified, and then introduced into the bipolar electrodialysis device (BPED), and the subsequent first crystallization step, Li2CO3 extraction step, and the step of removing carbonate ions from the Li2CO3 extraction filtrate using an aqueous HCl solution are performed as assumed using the basic solution of the bipolar electrodialysis device (BPED). Figures 18 to 29 show the results of analysis obtained by simulating the composition of the steps according to the process diagram of Figure 17.

[0134] From FIGS. 17 to 29, it was confirmed that the Li2CO3 extract filtrate from which carbonate ions have been removed has a Li content of approximately 300 mg / L, which is similar to the 250–300 mg / L level of the geothermal brine original brine composition, and is suitable for recycling as a brine source for the direct lithium extraction method.

[0135]

[0136] Although the present invention has been described above with reference to embodiments, the present invention is not limited by the embodiments disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. A step of obtaining a LiCl-containing brine treatment solution by extracting Li from brine by a direct lithium extraction method; A step of separating lithium ions from the above LiCl-containing brine treatment solution and producing an aqueous LiOH solution containing the separated lithium ions; The step of generating the above LiOH aqueous solution comprises introducing the above LiCl-containing brine treatment solution into a device equipped with an ion exchange membrane and a bipolar membrane to generate the above LiOH aqueous solution, and in the device, generating the above LiOH aqueous solution and the above HCl aqueous solution together according to the following Chemical Formula 1, and obtaining Li2CO3 using the above LiOH aqueous solution and carbon dioxide; and By mixing the aqueous HCl solution generated in the above device with the Li2CO3 extract remaining after obtaining the above Li2CO3, carbonate ions (CO3 2- After removing ) and recycling as a brine source Method for manufacturing lithium compounds. <Chemical Formula 1> LiCl + H2O → HCl + LiOH 2. A step of obtaining a LiCl-containing brine treatment solution by extracting Li from brine by the direct lithium extraction method; A step of concentrating the above LiCl-containing brine treatment solution; A step of purifying the concentrated LiCl-containing brine treatment solution by removing divalent cation impurities from the concentrated LiCl-containing brine treatment solution; A step of separating lithium ions from the purified LiCl-containing brine treatment solution and producing an aqueous LiOH solution containing the separated lithium ions; A step of obtaining crude lithium hydroxide by first crystallizing the above-mentioned aqueous LiOH solution; A step of obtaining a lithium hydroxide product by secondary crystallizing the above crude lithium hydroxide; A step of obtaining Li2CO3 by reacting the remaining amount of LiOH-containing liquid generated while producing the above lithium hydroxide product with carbon dioxide; and The method comprises the step of adding at least a portion of the obtained Li2CO3 to the concentrated LiCl-containing brine treatment solution to remove divalent cation impurities. The step of generating the above LiOH aqueous solution involves introducing the purified LiCl-containing brine treatment solution into a device equipped with an ion exchange membrane and a bipolar membrane to generate the above LiOH aqueous solution, and in the device, the above LiOH aqueous solution is generated together with the HCl aqueous solution according to the following Chemical Formula 1, and The Li2CO3 extract filtrate, obtained by reacting the remaining amount of LiOH-containing filtrate with carbon dioxide to extract Li2CO3, is mixed with an aqueous HCl solution generated by the above device to obtain carbonate ions (CO3 2- After removing ) and recycling as a brine source Method for manufacturing lithium compounds. <Chemical Formula 1> LiCl + H2O → HCl + LiOH 3. In Paragraph 1 or 2, The above direct lithium extraction method is a method utilizing any one selected from the group consisting of ion exchange, ion adsorption, solvent extraction, and combinations thereof. Method for manufacturing lithium compounds.

4. In Paragraph 1 or 2, The above LiCl-containing brine treatment solution is concentrated by at least one method selected from the group consisting of reverse osmosis, electrodialysis, MVR forced concentration, and combinations thereof. Method for manufacturing lithium compounds.

5. In Paragraph 2, LiOH is further added to the above concentrated LiCl-containing brine treatment solution to precipitate and remove the above divalent cation impurities. Method for manufacturing lithium compounds.

6. In Paragraph 5, At least a portion of the crude lithium hydroxide obtained by the above primary crystallization is used as LiOH added to remove the above divalent cation impurities. Method for manufacturing lithium compounds.

7. In Paragraph 2, The step of purifying the above-mentioned concentrated LiCl-containing brine treatment solution comprises a first purification step, and subsequently, further comprises a second purification step of removing impurities using an ion exchange resin. Method for manufacturing lithium compounds.

8. In Paragraph 2, The LiOH aqueous solution is produced by including lithium ions separated by the ion exchange membrane from the purified LiCl-containing brine treatment solution and hydroxide ions generated by the decomposition of water by electrodialysis in the bipolar membrane. Method for manufacturing lithium compounds.

9. In Paragraph 1 or 2, The concentration of the above HCl aqueous solution is 0.1 to 20 wt% Method for manufacturing lithium compounds.

10. In Paragraph 2, The step of purifying the above-mentioned concentrated LiCl-containing brine treatment solution is a first purification step, and subsequently, a second purification step of removing impurities using an ion exchange resin is further included, and the above-mentioned aqueous HCl solution is used as a washing solution to regenerate the ion exchange resin used in the second purification step, or The above HCl aqueous solution is used as a washing solution to regenerate the reverse osmosis membrane used in the step of concentrating the above LiCl-containing brine treatment solution, or The above LiCl-containing brine treatment solution is obtained by a direct lithium extraction method by ion exchange using an ion exchange membrane, and the above HCl aqueous solution is used as a washing solution to regenerate the ion exchange resin used in the above direct lithium extraction method. Method for manufacturing lithium compounds.

11. In Paragraph 7, A step of purifying the concentrated LiCl-containing brine treatment solution; and a second purification step of removing impurities using an ion exchange resin following the step of purifying the concentrated LiCl-containing brine treatment solution; and, without performing any additional purification steps other than those above, introducing the purified LiCl-containing brine treatment solution obtained thereby directly into a device equipped with the ion exchange membrane and the bipolar membrane to produce the LiOH aqueous solution. Method for manufacturing lithium compounds.

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