Method for extracting lithium from salt lake by using flow electrode, and device for extracting lithium from salt lake

Abstract

The present disclosure relates to the technical field of salt lake lithium extraction and recovery, and in particular to a method for extracting lithium from a salt lake by using a flow electrode, and a device for extracting lithium from a salt lake. By using a flow electrode slurry mixed with a lithium intercalation / deintercalation active material as a lithium ion electric deintercalation carrier, using a flow electrode slurry mixed with a calcium intercalation / deintercalation active material as a calcium ion electric deintercalation carrier, and incorporating an electrochemical principle, salt lake lithium extraction is carried out, and in the process of lithium intercalation, Ca2+ and Mg2+ generate a competitive effect when entering a flow electrode, so that magnesium ions do not easily enter a lithium-intercalated slurry by means of an ion exchange membrane, thereby inhibiting the intercalation of the magnesium ions into the lithium intercalation / deintercalation active material; and in a lithium intercalation / deintercalation system, the electrode potential of calcium ions is significantly different from that of lithium ions, so that the calcium ions cannot be intercalated into the lithium intercalation / deintercalation active material. Therefore, the method provided by the present disclosure can effectively separate lithium and magnesium, thereby improving the purity of recovered lithium.

Description

A method for extracting lithium from salt lake using mobile electrodes and a device for extracting lithium from salt lake Technical Field

[0001] The present disclosure belongs to the technical field of lithium extraction and recovery from salt lakes, and specifically relates to a method for extracting lithium from salt lakes using a mobile electrode and a device for extracting lithium from salt lakes. Background Art

[0002] In recent years, with the rapid development of new energy vehicles and chemical energy storage, the demand for lithium has increased dramatically. Salt lake brine contains huge lithium resources (accounting for about 70% of the world's lithium reserves), so lithium extraction from salt lakes has attracted more and more attention. In order to develop salt lake lithium resources, a variety of processes have emerged, including evaporation concentration, adsorption, extraction and membrane separation. Evaporation concentration is only suitable for extracting lithium from low magnesium-lithium ratio solutions (Mg / Li<6). Membrane separation is difficult to extract Li + and Na + / K + Separation requires the Na + and K + Pre-removal results in a large amount of lithium loss. For the extraction method, the organic extractant has a certain solubility in the brine, which brings potential pollution to the environment.

[0003] In response to the difficulties in extracting lithium from salt lakes, the electrochemical deintercalation method has become an emerging lithium extraction method with great development potential due to its environmental friendliness and high selectivity for lithium. The electrochemical deintercalation method utilizes the working principle of aqueous lithium batteries, using an ion sieve with a "memory effect" on lithium ions as the electrode material, salt lake brine as the cathode electrolyte, and a magnesium-free supporting electrolyte as the anode electrolyte, thus forming an electrochemical deintercalation system. Currently, electrointercalation mainly uses fixed electrodes as carriers for the adsorption and desorption of lithium ions. The contact area between the electrodes and the lithium-containing brine is small, and the continuous operation efficiency is low. The method of extracting lithium using a mobile electrode can solve the problems existing with fixed electrodes to a certain extent. It is easy to operate and can achieve continuous lithium extraction, thereby improving operating efficiency.

[0004] However, a common problem with current methods of lithium extraction using flow electrodes is the low purity of the recovered lithium, which greatly limits the application of flow electrodes in lithium extraction.

[0005] Summary of the Invention

[0006] The purpose of the present disclosure includes providing a method for extracting lithium from a salt lake using a mobile electrode and a salt lake lithium extraction device, aiming to effectively improve the purity of the recovered lithium.

[0007] In order to achieve the above-mentioned purpose of the present disclosure, the following technical solutions can be adopted:

[0008] In the first aspect, the solution provided by the present disclosure includes a method for extracting lithium from salt lakes using a mobile electrode, comprising: using a mobile electrode slurry mixed with a lithium intercalation and deintercalation active substance as a lithium ion electro-deintercalation carrier, and using a mobile electrode slurry mixed with a calcium intercalation and deintercalation active substance as a calcium ion electro-deintercalation carrier, and extracting lithium from salt lakes through electrochemical principles.

[0009] In some embodiments of the present disclosure, a lithium insertion stage and a lithium removal stage are performed sequentially. In the lithium insertion stage, lithium ions are removed from the lithium-containing brine and enter the lithium-deficient mobile electrode slurry to form a lithium-rich mobile electrode slurry, and calcium ions are simultaneously introduced into the lithium-containing brine. In the lithium removal stage, lithium ions are removed from the lithium-rich mobile electrode slurry and enter the lithium-rich recovery solution.

[0010] Among them, in the lithium-containing brine, the lithium content is 0.1g / L-5.0g / L, and the magnesium content is 100g / L-300g / L.

[0011] In some embodiments of the present disclosure, lithium extraction from salt lakes is carried out using an electrochemical device having a lithium intercalation module and a lithium decalcification module, wherein the lithium intercalation module includes a lithium intercalation channel, a lithium-containing brine channel and a calcium decalcification channel, and the lithium-containing brine channel is located between the lithium intercalation channel and the calcium decalcification channel; the lithium decalcification module includes a lithium decalcification channel, a recovery liquid channel and a calcium intercalation channel, and the recovery liquid channel is located between the decalcification channel and the calcium intercalation channel; the lithium intercalation channel and the decalcification channel are connected to form a lithium ion deintercalation circulation channel; the calcium decalcification channel and the calcium intercalation channel are connected to form a calcium ion deintercalation circulation channel; a cation exchange membrane and a current collector are provided on the inner walls of the lithium intercalation channel, the calcium decalcification channel and the delithiation channel, and an anion exchange membrane and a current collector are provided on the inner wall of the calcium intercalation channel.

[0012] In some embodiments of the present disclosure, the lithium insertion stage includes: placing a lithium-deficient mobile electrode slurry in a lithium insertion channel, placing a calcium-rich mobile electrode slurry in a decalcification channel, placing a lithium-containing brine in a lithium-containing brine channel, connecting the current collector of the lithium insertion channel and the current collector of the lithium insertion channel to a positive voltage electrode and a negative voltage electrode, respectively, applying a voltage to allow lithium ions in the lithium-containing brine to enter the lithium insertion channel, and forming a lithium-rich mobile electrode slurry in the lithium ion deintercalation circulation channel; calcium ions in the calcium-rich mobile electrode slurry are deintercalated into the lithium-containing brine channel, and forming a calcium-deficient mobile electrode slurry in the calcium ion deintercalation circulation channel.

[0013] In some embodiments of the present disclosure, the preparation process of the lithium-deficient mobile electrode slurry used in the lithium insertion stage includes: first mixing the lithium insertion and delithiation active material, the first conductive agent and the first salt solution to form a lithium-rich slurry, and then delithiating the lithium-rich slurry.

[0014] In some embodiments of the present disclosure, the lithium insertion and extraction active material is selected from LiMn2O4 / Li 1-x Mn2O4、LiFePO4 / Li1-x FePO4 and Li2TiO3 / Li 2-x At least one of TiO3.

[0015] In some embodiments of the present disclosure, the first salt solution is selected from at least one of a sodium chloride solution and a potassium chloride solution.

[0016] In some embodiments of the present disclosure, the concentration of the first salt solution is 0.5 mol / L-1.5 mol / L, and the solid content of the lithium-rich slurry is 30%-40%.

[0017] In some embodiments of the present disclosure, the mass ratio of the lithium insertion / extraction active material to the first conductive agent is (85-90):(10-15).

[0018] In some embodiments of the present disclosure, the first conductive agent is selected from at least one of conductive carbon black, acetylene black, and carbon nanotubes.

[0019] In some embodiments of the present disclosure, the preparation process of the calcium-rich mobile electrode slurry includes: mixing the calcium-embedding and decalcification active material, the second conductive agent, and the second salt solution.

[0020] In some embodiments of the present disclosure, the calcium-decalcifying active material is selected from CaMn2O4 / Ca 1-x Mn2O4、Ca x CuHCF / Ca 1-x CuHCF, CaCo2O4 / Ca 1-x Co2O4 and CaV6O 16 2.8H2O / Ca 1-x V6O 16 · At least one of 2.8H2O, wherein 0<x<1. .

[0021] In some embodiments of the present disclosure, the second saline solution is a sodium chloride solution.

[0022] In some embodiments of the present disclosure, the concentration of the second salt solution is 0.5 mol / L-1.5 mol / L, and the solid content in the calcium-rich mobile electrode slurry is 30%-40%.

[0023] In some embodiments of the present disclosure, the mass ratio of the intercalation and decalcification active material to the second conductive agent is (85-90):(10-15).

[0024] In some embodiments of the present disclosure, the second conductive agent is selected from at least one of conductive carbon black, acetylene black, and carbon nanotubes.

[0025] In some embodiments of the present disclosure, during the lithium insertion stage, the power-on voltage is controlled to be 0.5V-1.2V, and the power-on time is 4h-8h.

[0026] In some embodiments of the present disclosure, the delithiation stage includes: introducing a lithium salt solution into the recovery liquid channel, the lithium-rich mobile electrode slurry and the calcium-deficient mobile electrode slurry flow into the delithiation channel and the calcium-intercalation channel through a pipeline, introducing a calcium salt solution into the calcium-intercalation channel, connecting the current collector of the delithiation channel and the current collector of the calcium-intercalation channel to the positive voltage electrode and the negative voltage electrode respectively, applying a voltage, the lithium ions in the lithium-rich mobile electrode slurry are released into the recovery liquid channel, and the calcium ions in the calcium-intercalation channel are embedded in the calcium-deficient mobile electrode slurry.

[0027] In some embodiments of the present disclosure, during the delithiation stage, the power-on voltage is controlled to be 0.5V-1.2V, and the power-on time is 4h-8h.

[0028] In some embodiments of the present disclosure, in the lithium insertion and removal stages, the flow rates of the lithium ion insertion and removal circulation channels and the calcium ion insertion and removal circulation channels are independently controlled to be 2 mL / min-10 mL / min.

[0029] In some embodiments of the present disclosure, the lithium salt solution introduced into the recovery liquid channel is a lithium chloride solution.

[0030] In some embodiments of the present disclosure, the concentration of the lithium salt solution is 40 mmol / L-60 mmol / L.

[0031] In some embodiments of the present disclosure, the calcium salt solution introduced into the calcium-intercalating channel is a calcium chloride solution.

[0032] In some embodiments of the present disclosure, the mass fraction of the calcium salt solution is 60%-70%.

[0033] In some embodiments of the present disclosure, the current collectors on the lithium insertion channel, the calcium desorption channel, the lithium desorption channel, and the calcium insertion channel are all in a network shape.

[0034] In some embodiments of the present disclosure, porous materials are used to construct the three channels in the lithium insertion module and the three channels in the lithium removal module, and the current collector is located between the porous material and the corresponding ion exchange membrane.

[0035] In some embodiments of the present disclosure, the pore size of the porous material is 20 μm-40 μm.

[0036] In some embodiments of the present disclosure, the porous material is selected from at least one of a porous resin material and cordierite.

[0037] In some embodiments of the present disclosure, the porous resin material includes polyurethane resin, epoxy resin, and phenolic resin.

[0038] In a second aspect, the solution provided by the present disclosure also includes a salt lake lithium extraction device for implementing the method in any of the above embodiments, comprising a lithium intercalation module and a lithium decalcification module, the lithium intercalation module comprising a lithium intercalation channel, a lithium-containing brine channel and a decalcification channel, the lithium-containing brine channel being located between the lithium intercalation channel and the decalcification channel; the delithiation module comprising a delithiation channel, a recovery liquid channel and a calcium intercalation channel, the recovery liquid channel being located between the delithiation channel and the calcium intercalation channel; the lithium intercalation channel and the delithiation channel being connected to form a lithium ion deintercalation circulation channel; the decalcification channel and the calcium intercalation channel being connected to form a calcium ion deintercalation circulation channel; a cation exchange membrane and a current collector are provided on the inner walls of the lithium intercalation channel, the decalcification channel and the delithiation channel, and an anion exchange membrane and a current collector are provided on the inner wall of the calcium intercalation channel.

[0039] The present invention uses a mobile electrode slurry mixed with a lithium intercalation and deintercalation active material as a lithium ion intercalation and deintercalation carrier, and a mobile electrode slurry mixed with a calcium intercalation and deintercalation active material as a calcium ion intercalation and deintercalation carrier, and combines electrochemical principles to extract lithium from salt lakes. During the lithium intercalation process, lithium ions are intercalated while calcium ions are released into the lithium-containing brine. As the concentration of calcium ions increases, Ca 2+ The hydration radius is smaller than that of Mg 2+ The hydration radius, Ca 2+ and Mg 2+ The competition generated when entering the mobile electrode can make it more difficult for magnesium ions to pass through the ion exchange membrane into the lithium intercalation slurry, thereby inhibiting the insertion of magnesium ions into the lithium intercalation and deintercalation active material. In the lithium intercalation and deintercalation system, the electrode potential of calcium ions is significantly different from that of lithium ions, so calcium ions will not be inserted into the lithium intercalation and deintercalation active material. Therefore, the method provided by the present disclosure can effectively separate lithium and magnesium, thereby improving the purity of the recovered lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0041] FIG1 is a schematic diagram of the process principle for extracting lithium from a salt lake using a mobile electrode according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0042] The embodiments of the present disclosure will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended only to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. Where specific conditions are not specified in the examples, the experiments were performed under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0043] The endpoints of the ranges and any values ​​disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0044] The inventors discovered that the reason why the purity of recovered lithium is low in existing methods of extracting lithium from salt lakes using mobile electrodes is mainly due to the following: when lithium ions in the brine enter the lithium insertion channel through the cation exchange membrane, impurity cations in the brine also enter the lithium insertion channel. The high magnesium-to-lithium ratio brine contains a large amount of magnesium ions, and the radius of magnesium ions and lithium ions is relatively close, making it easy for them to compete with lithium ions and be inserted into the electrode material, resulting in a decrease in the purity of the recovered lithium and the electrode capacity, thereby reducing the efficiency of lithium extraction. In view of this, the inventors improved the carrier of the mobile electrode, by inhibiting the entry of magnesium ions into the mobile electrode, thereby improving the purity of the recovered lithium.

[0045] In the first aspect, the solution provided by the present disclosure includes a method for extracting lithium from salt lakes using a mobile electrode, which is characterized by comprising: using a mobile electrode slurry mixed with a lithium intercalation and deintercalation active substance as a lithium ion electro-deintercalation carrier, and using a mobile electrode slurry mixed with a calcium intercalation and deintercalation active substance as a calcium ion electro-deintercalation carrier, and extracting lithium from salt lakes through electrochemical principles.

[0046] It should be noted that during the lithium insertion process, lithium ions are inserted into the lithium-containing brine while calcium ions are released. As the concentration of calcium ions increases, Ca 2+ The hydration radius is smaller than that of Mg 2+ The hydration radius, Ca 2+ and Mg 2+ The competition generated when entering the mobile electrode can make it more difficult for magnesium ions to pass through the ion exchange membrane into the lithium intercalation slurry, thereby inhibiting the insertion of magnesium ions into the lithium intercalation and deintercalation active material. In the lithium intercalation and deintercalation system, the electrode potential of calcium ions is significantly different from that of lithium ions, so calcium ions will not be inserted into the lithium intercalation and deintercalation active material. Therefore, the method provided by the present disclosure can effectively separate lithium and magnesium, thereby improving the purity of the recovered lithium.

[0047] In actual operation, as shown in Figure 1, the method of extracting lithium from a mobile electrode salt lake includes a lithium insertion stage and a lithium removal stage. In the lithium insertion stage, lithium ions are removed from the lithium-containing brine and enter the lithium-deficient mobile electrode slurry to form a lithium-rich mobile electrode slurry, while calcium ions are simultaneously introduced into the lithium-containing brine. In the lithium removal stage, lithium ions are removed from the lithium-rich mobile electrode slurry and enter the lithium-rich recovery solution. The lithium content in the lithium-containing brine is 0.1g / L-5.0g / L, and the magnesium content is 100g / L-300g / L.

[0048] Specifically, the following steps may be included:

[0049] S1. Construct lithium insertion module and lithium removal module

[0050] Lithium is extracted from salt lakes using an electrochemical device with a lithium insertion module and a lithium removal module. Lithium insertion is first performed to allow lithium ions to enter the channels of the lithium insertion module from lithium-containing brine, and then lithium removal is performed to allow lithium ions to enter the lithium-rich recovery liquid from the channels of the lithium removal module.

[0051] The lithium insertion module includes a lithium insertion channel, a lithium-containing brine channel, and a calcium deintercalation channel, with the lithium-containing brine channel located between the lithium insertion and decalcification channels. The delithiation module includes a lithium deintercalation channel, a recovery fluid channel, and a calcium insertion channel, with the recovery fluid channel located between the delithiation and calcium insertion channels. The lithium insertion and delithiation channels are connected by a pipeline to form a lithium ion insertion and deintercalation circulation channel; the calcium deintercalation and calcium insertion channels are connected by a pipeline to form a calcium ion insertion and deintercalation circulation channel.

[0052] That is, both the lithium insertion module and the lithium removal module contain three channels. In the lithium insertion module, lithium-containing brine is placed in the lithium-containing brine channel in the middle. The lithium insertion channel is filled with lithium-deficient flowing electrode slurry, while the calcium removal channel is filled with calcium-rich flowing electrode slurry. In the lithium removal module, lithium-rich recovery liquid is placed in the recovery liquid channel in the middle. The lithium removal channel is filled with lithium-rich flowing electrode slurry, while the calcium insertion channel is filled with calcium-deficient flowing electrode slurry. During the lithium insertion and delithiation stages, both the lithium ion deintercalation circulation channel and the calcium ion deintercalation circulation channel circulate, allowing for controllable flow rates.

[0053] Furthermore, the inner walls of the lithium insertion channel, calcium desorption channel, and lithium removal channel are all provided with a cation exchange membrane and a current collector, while the inner wall of the calcium insertion channel is provided with an anion exchange membrane and a current collector. The current collector is not shown in FIG1 . To avoid affecting the passage of ions, the current collectors on the lithium insertion channel, calcium desorption channel, lithium removal channel, and calcium insertion channel are all mesh-like structures, such as titanium mesh, and can be cylindrical in shape.

[0054] In some embodiments of the present disclosure, porous materials are used to construct the three channels in the lithium insertion module and the three channels in the lithium removal module. Current collectors are located between the porous materials and the corresponding ion exchange membranes, with the ion exchange membranes located at the innermost end, contacting the electrode slurry. Without the action of an electric field, ions will not continue to migrate and will not pass through the outer porous material.

[0055] Furthermore, the pore size of the porous material is 20 μm-40 μm, such as 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, etc.

[0056] In some embodiments of the present disclosure, the porous material is selected from at least one of a porous resin material and cordierite, and may be any one or more of the porous resin material. The porous resin material includes, but is not limited to, polyurethane resin, epoxy resin, and phenolic resin.

[0057] S2, lithium insertion stage

[0058] As shown in Figure 1, the lithium-deficient mobile electrode slurry is placed in the lithium intercalation channel, the calcium-rich mobile electrode slurry is placed in the decalcification channel, and the lithium-containing brine is placed in the lithium-containing brine channel. The current collector of the lithium intercalation channel and the current collector of the lithium intercalation channel are connected to the positive voltage electrode and the negative voltage electrode respectively. A constant voltage is applied to allow the lithium ions in the lithium-containing brine to pass through the porous material and the cation exchange membrane into the lithium intercalation channel and embed into the lithium-deficient mobile electrode, forming a lithium-rich mobile electrode slurry in the lithium ion deintercalation cycle channel. The calcium ions in the calcium-rich mobile electrode in the decalcification channel are released and enter the lithium-containing brine channel, forming a calcium-deficient mobile electrode slurry in the calcium ion deintercalation cycle channel. The lithium-rich mobile electrode slurry and the calcium-deficient mobile electrode slurry are the starting slurries for the delithiation stage.

[0059] It should be noted that by using the decalcification channel and the calcium insertion channel to form a loop, the lithium insertion channel and the delithiation channel to form a loop. In the lithium insertion module, while lithium ions are inserted into the lithium insertion channel, calcium ions are extracted from the calcium insertion active material and enter the brine through the porous material to flow to the negative electrode. As the concentration of calcium ions increases, Ca 2+ The hydration radius is smaller than that of Mg 2+ The hydration radius of the magnesium ions is small, so it produces a competitive effect when passing through the cationic membrane, reducing the permeability of magnesium ions, thereby effectively separating lithium and magnesium, thereby improving the purity of the recovered lithium.

[0060] In some embodiments of the present disclosure, the preparation process of the lithium-deficient mobile electrode slurry used in the lithium insertion stage includes: first mixing a lithium insertion / extraction active material, a first conductive agent, and a first salt solution to form a lithium-rich slurry, and then delithiating the lithium-rich slurry. The lithium insertion / extraction active material and the first conductive agent may be first uniformly mixed and then added to the first salt solution to form a uniform slurry, but is not limited thereto.

[0061] Furthermore, the lithium insertion and extraction active material is selected from LiMn2O4 / Li 1-x Mn2O4、LiFePO4 / Li 1-x FePO4 and Li2TiO3 / Li 2-x At least one of TiO3 can be any one or more of the above. The first salt solution is selected from at least one of sodium chloride solution and potassium chloride solution, which can be any one or more of the above. For example: LiMn2O4 / Li 1-x Mn2O4 represents a lithium-insertion and extraction electrode system, LiMn2O4 represents a lithium-rich electrode, Li 1-x Mn2O4 represents the corresponding under-lithiated electrode.

[0062] Furthermore, the concentration of the first salt solution is 0.5mol / L-1.5mol / L, and the solid content of the lithium-rich slurry is 30%-40%. The mass ratio of the lithium-insertion active material and the first conductive agent is (85-90): (10-15). The concentration of the slurry is further controlled to improve the effect of lithium extraction. Specifically, the concentration of the first salt solution can be 0.5mol / L, 1.0mol / L, 1.5mol / L, etc., the solid content of the lithium-rich slurry is 30%, 35%, 40%, etc., and the mass ratio of the lithium-insertion active material and the first conductive agent can be 85:15, 86:14, 87:13, 88:12, 89:11, 90:10, etc.

[0063] In some embodiments of the present disclosure, the preparation process of the calcium-rich mobile electrode slurry includes: mixing the calcium-intercalating and decalcifying active material, a second conductive agent, and a second salt solution to form a uniform slurry. The calcium-intercalating and decalcifying active material and the second conductive agent may be mixed uniformly before being added to the second salt solution to form a uniform slurry, but the present invention is not limited thereto.

[0064] In some embodiments of the present disclosure, the calcium-decalcifying active material is selected from CaMn2O4 / Ca 1-x Mn2O4、Ca x CuHCF / Ca 1-x CuHCF, CaCo2O4 / Ca 1-x Co2O4 and CaV6O 16 2.8H2O / Ca 1-x V6O 16 At least one of 2.8H2O can be any one or more of the above, wherein 0<x<1. The second salt solution can be a sodium chloride solution, but is not limited thereto.

[0065] In some embodiments of the present disclosure, the concentration of the second salt solution is 0.5mol / L-1.5mol / L, and the solid content in the calcium-rich mobile electrode slurry is 30%-40%. The mass ratio of the embedded decalcification active material and the second conductive agent is (85-90): (10-15). The concentration of the slurry is further controlled to control the content of calcium ions entering the brine. Specifically, the concentration of the second salt solution can be 0.5mol / L, 1.0mol / L, 1.5mol / L, etc., the solid content of the calcium-rich mobile electrode slurry is 30%, 35%, 40%, etc., and the mass ratio of the embedded decalcification active material and the second conductive agent can be 85:15, 86:14, 87:13, 88:12, 89:11, 90:10, etc.

[0066] Furthermore, the first conductive agent and the second conductive agent can be independently selected from at least one of conductive carbon black, acetylene black and carbon nanotubes, and can be any one or more of the above.

[0067] In some embodiments of the present disclosure, during the lithium insertion stage, the power-on voltage is controlled to be 0.5V-1.2V, the power-on time is 4h-8h, and the flow rates of the lithium ion deintercalation circulation channel and the calcium ion deintercalation circulation channel are independently controlled to be 2mL / min-10mL / min to ensure that the lithium extraction process is fully carried out.

[0068] Specifically, in the lithium insertion stage, the controlled power-on voltage can be 0.5V, 1.0V, 1.2V, etc., and the flow rates of the lithium ion deintercalation circulation channel and the calcium ion deintercalation circulation channel can be the same or unlimited, and can be independently 2mL / min, 3mL / min, 5mL / min, 8mL / min, 10mL / min, etc.

[0069] S3, delithiation stage

[0070] As shown in Figure 1, a lithium salt solution is introduced into the recovery liquid channel, and the lithium-rich mobile electrode slurry and the calcium-deficient mobile electrode slurry flow into the lithium-depletion channel and the calcium-intercalation channel through pipes. A calcium salt solution is introduced into the calcium-intercalation channel, and the current collector of the lithium-depletion channel and the current collector of the calcium-intercalation channel are connected to the positive voltage electrode and the negative voltage electrode respectively. A constant voltage is applied, and the lithium ions in the lithium-rich mobile electrode slurry are released into the recovery liquid channel to obtain a lithium-rich recovery liquid; the calcium ions in the calcium-intercalation channel are embedded in the calcium-deficient mobile electrode slurry. To meet the ion balance, chloride ions enter the lithium-rich recovery liquid through the anion exchange membrane.

[0071] In some embodiments of the present disclosure, the lithium salt solution introduced into the recovery liquid channel may be a lithium chloride solution, and the calcium salt solution introduced into the calcium insertion channel may be a calcium chloride solution, but is not limited thereto. The anion species of the lithium salt solution and the anion species of the calcium salt solution may be the same. The concentration of the lithium salt solution may be 40 mmol / L-60 mmol / L, such as 40 mmol / L, 50 mmol / L, 60 mmol / L, etc. The mass fraction of the calcium salt solution is 60%-70%, such as 60%, 65%, 70%, etc.

[0072] In some embodiments of the present disclosure, during the delithiation stage, the voltage is controlled to be 0.5V-1.2V, the duration is 4h-8h, and the flow rates of the lithium ion deintercalation and calcium ion deintercalation circulation channels are independently controlled to be 2mL / min-10mL / min. By further controlling the operating parameters, lithium ions can be more fully introduced into the lithium-rich recovery solution.

[0073] Specifically, in the delithiation stage, the controlled power-on voltage can be 0.5V, 1.0V, 1.2V, etc., and the flow rates of the lithium ion deintercalation circulation channel and the calcium ion deintercalation circulation channel can be the same or unlimited, and can be independently 2mL / min, 3mL / min, 5mL / min, 8mL / min, 10mL / min, etc.

[0074] In some embodiments of the present disclosure, the process of extracting lithium from salt lakes may further include: re-flowing the lithium-deficient mobile electrode slurry and the calcium-rich mobile electrode slurry formed in the delithiation stage into the lithium insertion channel and the decalcification channel through a pipeline for a cyclic reaction of 4h-8h, such as 4h, 5h, 6h, 7h, 8h, etc.

[0075] The embodiment of the present disclosure also provides a salt lake lithium extraction device for implementing the above method, including a lithium intercalation module and a lithium decalcification module, the lithium intercalation module including a lithium intercalation channel, a lithium-containing brine channel and a calcium decalcification channel, and the lithium-containing brine channel is located between the lithium intercalation channel and the calcium decalcification channel; the lithium decalcification module including a lithium decalcification channel, a recovery liquid channel and a calcium intercalation channel, and the recovery liquid channel is located between the decalcification channel and the calcium intercalation channel; the lithium intercalation channel and the decalcification channel are connected to form a lithium ion decalcification circulation channel; the calcium decalcification channel and the calcium intercalation channel are connected to form a calcium ion decalcification circulation channel; the inner walls of the lithium intercalation channel, the calcium decalcification channel and the delithiation channel are all provided with a cation exchange membrane and a current collector, and the inner wall of the calcium intercalation channel is provided with an anion exchange membrane and a current collector.

[0076] It should be noted that the specific structures of the lithium insertion module and the lithium removal module can be found in the above description and will not be repeated here.

[0077] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0078] It should be noted that the apparatus for extracting lithium from salt lakes used in the following examples is shown in Figure 1. Polyurethane resin with a pore size of 30 μm is used to construct the three channels in the lithium insertion module and the three channels in the lithium removal module. The channels are cylindrical in shape with a diameter of 30 cm. The current collector uses a titanium mesh with a pore size of 1.5 mm and a thickness of 2 mm. The cation exchange membrane uses a polyvinylidene fluoride homogeneous ion exchange membrane with a thickness of 0.5 mm, and the anion exchange membrane uses a polyvinylidene fluoride homogeneous ion exchange membrane with a thickness of 0.5 mm.

[0079] Example 1

[0080] This embodiment provides a method for extracting lithium from a salt lake using a mobile electrode, comprising the following steps:

[0081] (1) LiMn2O4 active material and conductive carbon black were added to 1 mol / L NaCl solution in a mass ratio of 85:15 to prepare a mobile electrode slurry with a solid content of 35%. The mobile electrode slurry was delithiated to form a lithium-deficient mobile electrode slurry: the prepared mobile electrode slurry was used as the anode and the inert carbon electrode was used as the cathode. The delithiation voltage was controlled at 1 V until the current density dropped to 0.5 A / m 2 The under-lithiated electrode can be obtained as follows.

[0082] CaV6O 16 · 2.8H2O active material and conductive carbon black were added to 1 mol / L NaCl solution in a mass ratio of 85:15 to obtain a calcium-rich mobile electrode slurry. The solid content of the mobile electrode slurry was 30%.

[0083] (2) Brine was introduced into the lithium-containing brine channel, and lithium-deficient mobile electrode slurry and calcium-rich mobile electrode slurry were introduced into the lithium insertion channel and the calcium-decalcification channel, respectively. The current collector in the calcium-decalcification channel and the current collector in the lithium insertion channel were connected to the positive and negative electrodes, respectively. A constant voltage of 0.9 V was applied, and the power was applied for 6 hours. The flow rate of the electrode slurry was 5 mL / min. The lithium ions in the brine passed through the porous material and the cation exchange membrane into the lithium insertion channel and were embedded in the lithium-deficient mobile electrode to obtain the lithium-rich mobile electrode slurry. The calcium ions in the calcium-rich electrode in the calcium-decalcification channel were released to obtain the calcium-deficient mobile electrode slurry.

[0084] (3) A lithium chloride solution with a concentration of 50 mmol / L is introduced into the recovery liquid channel, and the lithium-rich mobile electrode slurry and the calcium-deficient mobile electrode slurry in step (2) flow into the lithium-depletion channel and the calcium-intercalation channel through the pipeline at a speed of 5 mL / min. At the same time, a calcium chloride solution with a concentration of 65% is introduced into the calcium-intercalation channel at a flow rate of 5 mL / min. The current collector in the lithium-depletion channel and the current collector in the calcium-intercalation channel are connected to the positive and negative electrodes, respectively. The constant voltage is controlled at 0.9 V, and the power-on time is 6 hours. The lithium ions in the lithium-rich mobile electrode are desorbed into the recovery liquid to obtain a lithium-rich recovery liquid, and the calcium ions in the calcium-intercalation channel are embedded in the calcium-deficient electrode.

[0085] Example 2

[0086] This embodiment provides a method for extracting lithium from a salt lake using a mobile electrode, comprising the following steps:

[0087] (1) LiMn2O4 active material and conductive carbon black were added to 1 mol / L NaCl solution in a mass ratio of 90:10 to prepare a mobile electrode slurry with a solid content of 30%. The mobile electrode slurry was delithiated to form a lithium-deficient mobile electrode slurry: the prepared mobile electrode slurry was used as the anode and the inert carbon electrode was used as the cathode. The delithiation voltage was controlled at 1 V until the current density dropped to 0.5 A / m 2 The under-lithiated electrode can be obtained as follows.

[0088] CaV6O 16 · 2.8H2O active material and conductive carbon black were added to 1 mol / L NaCl solution in a mass ratio of 90:10 to obtain a calcium-rich mobile electrode slurry. The solid content of the mobile electrode slurry was 35%.

[0089] (2) Brine was introduced into the lithium-containing brine channel, and lithium-deficient mobile electrode slurry and calcium-rich mobile electrode slurry were introduced into the lithium insertion channel and the calcium-decalcification channel, respectively. The current collector in the calcium-decalcification channel and the current collector in the lithium insertion channel were connected to the positive and negative electrodes, respectively. A constant voltage of 1.1 V was applied for 4 hours. The flow rate of the electrode slurry was 8 mL / min. The lithium ions in the brine passed through the porous material and the cation exchange membrane into the lithium insertion channel and were embedded in the lithium-deficient mobile electrode to obtain the lithium-rich mobile electrode slurry. The calcium ions in the calcium-rich electrode in the calcium-decalcification channel were released to obtain the calcium-deficient mobile electrode slurry.

[0090] (3) A lithium chloride solution with a concentration of 50 mmol / L is introduced into the recovery liquid channel, and the lithium-rich mobile electrode slurry and the calcium-deficient mobile electrode slurry in step (2) flow into the lithium-depletion channel and the calcium-intercalation channel through the pipeline at a speed of 8 mL / min. At the same time, a calcium chloride solution with a concentration of 70% is introduced into the calcium-intercalation channel at a flow rate of 8 mL / min. The current collector in the lithium-depletion channel and the current collector in the calcium-intercalation channel are connected to the positive and negative electrodes, respectively. The constant voltage is controlled at 1.1 V, and the power-on time is 4 h. The lithium ions in the lithium-rich mobile electrode are desorbed into the recovery liquid to obtain a lithium-rich recovery liquid, and the calcium ions in the calcium-intercalation channel are embedded in the calcium-deficient electrode.

[0091] (4) The lithium-deficient mobile electrode slurry and the calcium-rich mobile electrode slurry in step (3) are re-flowed into the lithium insertion channel and the calcium removal channel through the pipeline for a cyclic reaction of 3 hours.

[0092] Example 3

[0093] This embodiment provides a method for extracting lithium from a salt lake using a mobile electrode, comprising the following steps:

[0094] (1) LiMn2O4 active material and conductive carbon black were added to 1 mol / L NaCl solution in a mass ratio of 85:15 to prepare a mobile electrode slurry with a solid content of 40%. The mobile electrode slurry was delithiated to form a lithium-deficient mobile electrode slurry: the prepared mobile electrode slurry was used as the anode and the inert carbon electrode was used as the cathode. The delithiation voltage was controlled at 1 V until the current density dropped to 0.5 A / m 2 The under-lithiated electrode can be obtained as follows.

[0095] CaV6O 16 · 2.8H2O active material and conductive carbon black were added to 1 mol / L NaCl solution in a mass ratio of 85:15 to obtain a calcium-rich mobile electrode slurry. The solid content of the mobile electrode slurry was 40%.

[0096] (2) Brine was introduced into the lithium-containing brine channel, and lithium-deficient mobile electrode slurry and calcium-rich mobile electrode slurry were introduced into the lithium insertion channel and the calcium-decalcification channel, respectively. The current collector in the calcium-decalcification channel and the current collector in the lithium insertion channel were connected to the positive and negative electrodes, respectively. A constant voltage of 0.7 V was applied, and the power was applied for 8 hours. The flow rate of the electrode slurry was 2 mL / min. The lithium ions in the brine passed through the porous material and the cation exchange membrane into the lithium insertion channel and were embedded in the lithium-deficient mobile electrode to obtain the lithium-rich mobile electrode slurry. The calcium ions in the calcium-rich electrode in the calcium-decalcification channel were released to obtain the calcium-deficient mobile electrode slurry.

[0097] (3) A lithium chloride solution with a concentration of 50 mmol / L is introduced into the recovery liquid channel, and the lithium-rich mobile electrode slurry and the calcium-deficient mobile electrode slurry in step (2) flow into the lithium-depletion channel and the calcium-intercalation channel through the pipeline at a speed of 2 mL / min. At the same time, a calcium chloride solution with a concentration of 60% is introduced into the calcium-intercalation channel at a flow rate of 2 mL / min. The current collector in the lithium-depletion channel and the current collector in the calcium-intercalation channel are connected to the positive and negative electrodes, respectively. The constant voltage is controlled at 0.7 V, and the power-on time is 8 h. The lithium ions in the lithium-rich mobile electrode are desorbed into the recovery liquid to obtain a lithium-rich recovery liquid, and the calcium ions in the calcium-intercalation channel are embedded in the calcium-deficient electrode.

[0098] (4) The lithium-deficient mobile electrode slurry and the calcium-rich mobile electrode slurry in step (3) are re-flowed into the lithium insertion channel and the calcium removal channel through the pipeline for a cyclic reaction of 9 hours.

[0099] Example 4

[0100] This embodiment provides a method for extracting lithium from salt lakes using a mobile electrode. The difference from embodiment 1 is that the active material for lithium insertion and removal is LiFePO4 active material, and the active material for calcium insertion and removal is Ca x CuHCF active material.

[0101] Example 5

[0102] This embodiment provides a method for extracting lithium from a salt lake using a mobile electrode. The difference from Example 1 is that the voltage for lithium extraction and delithiation is 2V.

[0103] Example 6

[0104] This embodiment provides a method for extracting lithium from a salt lake using a mobile electrode. The difference from Example 1 is that the voltage for lithium extraction and delithiation is 0.3V.

[0105] Comparative Example

[0106] This embodiment provides a method for extracting lithium from salt lakes using a mobile electrode. The difference from Example 1 is that the calcium-deintercalating active substance in the calcium-deintercalating channel is replaced with activated carbon, and an anion exchange membrane is provided on the inner wall of the activated carbon flow channel. Other parameters are the same as those in Example 1.

[0107] Test example

[0108] The lithium extraction effects of the examples and comparative examples were tested, and the results are shown in Table 1.

[0109] Test method: The lithium ion concentration and magnesium ion concentration before and after the reaction and the purity of the recovered lithium were tested using an inductively coupled plasma spectrometer (ICP), as shown in Table 1.

[0110] Table 1 Lithium ion concentration and magnesium ion concentration before and after reaction and recovered lithium purity

[0111] As can be seen from the examples and comparative examples, the lithium recovery rates in the examples are all greater than 90%, the concentration of magnesium ions in the recovered liquid of Example 1 is at least 0.78 g / L lower than that of the comparative example, the impurity content in the recovered liquid is reduced, and the purity of the lithium ions is improved, indicating that the competitive effect of calcium ions and magnesium ions in the lithium extraction process effectively prevents magnesium ions from entering the lithium insertion channel, thereby improving the lithium extraction efficiency. Comparing Example 1 with Examples 5-6, it can be seen that: excessive lithium extraction voltage leads to side reactions that reduce the lithium extraction efficiency, and excessively low lithium extraction voltage leads to too low a reaction rate, resulting in reduced lithium extraction efficiency. Industrial Applicability

[0112] This invention utilizes a mobile electrode slurry mixed with a lithium intercalation / deintercalation active material as a lithium ion electro-deintercalation carrier, and a mobile electrode slurry mixed with a calcium intercalation / deintercalation active material as a calcium ion electro-deintercalation carrier, combining electrochemical principles to extract lithium from salt lakes. The disclosed salt lake lithium extraction device can be easily operated and effectively separate lithium and magnesium, thereby improving the purity of the recovered lithium, demonstrating excellent industrial applicability.

Claims

1. A method for extracting lithium from a salt lake using a mobile electrode, characterized in that: include: Lithium is extracted from salt lakes by electrochemical principles using a flowing electrode slurry mixed with lithium intercalation and deintercalation active substances as a lithium ion intercalation and deintercalation carrier, and a flowing electrode slurry mixed with calcium intercalation and deintercalation active substances as a calcium ion intercalation and deintercalation carrier.

2. The method according to claim 1, characterized in that The process of extracting lithium from salt lakes includes a lithium insertion stage and a lithium removal stage, in which lithium ions are removed from lithium-containing brine and enter lithium-deficient mobile electrode slurry to form lithium-rich mobile electrode slurry, and calcium ions are simultaneously introduced into the lithium-containing brine; in the lithium removal stage, lithium ions are removed from the lithium-rich mobile electrode slurry and enter lithium-rich recovery liquid; Wherein, in the lithium-containing brine, the lithium content is 0.1g / L-5.0g / L, and the magnesium content is 100g / L-300g / L.

3. The method according to claim 1 or 2, characterized in that: Lithium is extracted from salt lakes using an electrochemical device having a lithium insertion module and a lithium removal module, wherein the lithium insertion module comprises a lithium insertion channel, a lithium-containing brine channel and a calcium removal channel, wherein the lithium-containing brine channel is located between the lithium insertion channel and the calcium removal channel; the lithium removal module comprises a lithium removal channel, a recovery liquid channel and a calcium insertion channel, wherein the recovery liquid channel is located between the lithium removal channel and the calcium insertion channel; the lithium insertion channel and the lithium removal channel are connected to form a lithium ion insertion and removal circulation channel; the calcium removal channel and the calcium insertion channel are connected to form a calcium ion insertion and removal circulation channel; cation exchange membranes and current collectors are provided on the inner walls of the lithium insertion channel, the calcium removal channel and the lithium removal channel, and an anion exchange membrane and current collector are provided on the inner wall of the calcium insertion channel.

4. The method according to claim 3, characterized in that: The lithium insertion stage includes: placing a lithium-deficient mobile electrode slurry in the lithium insertion channel, placing a calcium-rich mobile electrode slurry in the decalcification channel, placing a lithium-containing brine in the lithium-containing brine channel, connecting the current collector of the lithium insertion channel and the current collector of the lithium insertion channel to a positive voltage pole and a negative voltage pole respectively, applying a voltage so that the lithium ions in the lithium-containing brine enter the lithium insertion channel, and a lithium-rich mobile electrode slurry is formed in the lithium ion deintercalation circulation channel; the calcium ions in the calcium-rich mobile electrode slurry are deintercalated and enter the lithium-containing brine channel, and a calcium-deficient mobile electrode slurry is formed in the calcium ion deintercalation circulation channel.

5. The method according to claim 4, characterized in that The preparation process of the lithium-deficient mobile electrode slurry used in the lithium insertion stage includes: firstly mixing the lithium insertion and extraction active material, the first conductive agent and the first salt solution to form a lithium-rich slurry, and then de-lithiating the lithium-rich slurry.

6. The method according to claim 5, characterized in that The lithium insertion and extraction active material is selected from LiMn2O4 / Li 1-x Mn2O4、LiFePO4 / Li 1-x FePO4 and Li2TiO3 / Li 2-x At least one of TiO3.

7. The method according to claim 5 or 6, characterized in that: The first salt solution is selected from at least one of a sodium chloride solution and a potassium chloride solution.

8. The method according to any one of claims 5 to 7, characterized in that: The concentration of the first salt solution is 0.5 mol / L-1.5 mol / L, and the solid content of the lithium-rich slurry is 30%-40%.

9. The method according to any one of claims 5 to 8, characterized in that: The mass ratio of the lithium insertion and extraction active material to the first conductive agent is (85-90): (10-15).

10. The method according to any one of claims 5 to 9, characterized in that: The first conductive agent is selected from at least one of conductive carbon black, acetylene black and carbon nanotubes.

11. The method according to any one of claims 4 to 10, characterized in that: The preparation process of the calcium-rich mobile electrode slurry comprises: mixing the calcium embedding and decalcification active material, the second conductive agent and the second salt solution.

12. The method according to claim 11, characterized in that The calcium-decalcifying active material is selected from CaMn2O4 / Ca 1-x Mn2O4、Ca x CuHCF / Ca 1-x CuHCF, CaCo2O4 / Ca 1-x Co2O4 and CaV6O 16 2.8H2O / Ca 1-x V6O 16 · At least one of 2.8H2O, wherein 0<x<1.

13. The method according to claim 11 or 12, characterized in that: The second salt solution is a sodium chloride solution.

14. The method according to any one of claims 11 to 13, characterized in that The concentration of the second salt solution is 0.5 mol / L-1.5 mol / L, and the solid content in the calcium-rich flowing electrode slurry is 30%-40%.

15. The method according to any one of claims 11 to 14, characterized in that The mass ratio of the calcium embedding and decalcification active material to the second conductive agent is (85-90): (10-15).

16. The method according to any one of claims 11 to 15, characterized in that The second conductive agent is selected from at least one of conductive carbon black, acetylene black and carbon nanotubes.

17. The method according to any one of claims 4 to 16, characterized in that: During the lithium insertion stage, the power-on voltage is controlled to be 0.5V-1.2V, and the power-on time is 4h-8h.

18. The method according to any one of claims 4 to 17, characterized in that: The delithiation stage includes: introducing a lithium salt solution into the recovery liquid channel, the lithium-rich mobile electrode slurry and the calcium-deficient mobile electrode slurry flow into the lithium desorption channel and the calcium insertion channel through a pipeline, introducing a calcium salt solution into the calcium insertion channel, connecting the current collector of the lithium desorption channel and the current collector of the calcium insertion channel to a positive voltage electrode and a negative voltage electrode respectively, applying a voltage, and the lithium ions in the lithium-rich mobile electrode slurry are released into the recovery liquid channel, and the calcium ions in the calcium insertion channel are embedded in the calcium-deficient mobile electrode slurry.

19. The method according to claim 18, characterized in that In the delithiation stage, the power-on voltage is controlled to be 0.5V-1.2V, and the power-on time is 4h-8h.

20. The method according to any one of claims 4 to 19, characterized in that In the lithium insertion stage and the lithium removal stage, the flow rates of the lithium ion insertion and removal circulation channel and the calcium ion insertion and removal circulation channel are independently controlled to be 2 mL / min-10 mL / min.

21. The method according to any one of claims 18 to 20, characterized in that The lithium salt solution introduced into the recovery liquid channel is a lithium chloride solution.

22. The method according to any one of claims 18 to 21, characterized in that The concentration of the lithium salt solution is 40mmol / L-60mmol / L.

23. The method according to any one of claims 18 to 22, characterized in that The calcium salt solution introduced into the calcium embedding channel is a calcium chloride solution.

24. The method according to any one of claims 18 to 23, characterized in that The mass fraction of the calcium salt solution is 60%-70%.

25. The method according to any one of claims 3 to 24, characterized in that The lithium insertion channel, the calcium desorption channel, the lithium desorption channel and the current collector on the calcium insertion channel are all in a mesh shape.

26. The method according to claim 25, characterized in that The three channels in the lithium insertion module and the three channels in the lithium removal module are constructed using porous materials, and the current collector is located between the porous material and the corresponding ion exchange membrane.

27. The method according to claim 26, characterized in that The pore size of the porous material is 20 μm-40 μm.

28. The method according to claim 26 or 27, characterized in that The porous material is selected from at least one of a porous resin material and cordierite.

29. The method according to claim 28, characterized in that The porous resin material includes polyurethane resin, epoxy resin and phenolic resin.

30. A salt lake lithium extraction device for implementing the method according to any one of claims 1 to 29, characterized in that: It comprises a lithium insertion module and a lithium removal module, wherein the lithium insertion module comprises a lithium insertion channel, a lithium-containing brine channel and a calcium removal channel, wherein the lithium-containing brine channel is located between the lithium insertion channel and the calcium removal channel; the lithium removal module comprises a lithium removal channel, a recovery liquid channel and a calcium insertion channel, wherein the recovery liquid channel is located between the lithium removal channel and the calcium insertion channel; the lithium insertion channel and the lithium removal channel are connected to form a lithium ion insertion and removal circulation channel; the calcium removal channel and the calcium insertion channel are connected to form a calcium ion insertion and removal circulation channel; the inner walls of the lithium insertion channel, the calcium removal channel and the lithium removal channel are all provided with a cation exchange membrane and a current collector, and the inner wall of the calcium insertion channel is provided with an anion exchange membrane and a current collector.

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