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

Abstract

The present disclosure belongs to the technical field of lithium extraction and recovery from salt lakes, and particularly relates to a method for extracting lithium from salt lakes by using a flow electrode and a device for extracting lithium from salt lakes. 2+ and Mg 2+ The competitive effect when entering the flow electrode can make it more difficult for magnesium ions to enter the lithium-embedding slurry through the ion exchange membrane, thereby inhibiting the embedding of magnesium ions into the lithium-embedding and -extracting active material; and the electrode potential of calcium ions in the lithium-embedding and -extracting system is quite different from that of lithium ions, so calcium ions will not be embedded into the lithium-embedding and -extracting active material. Therefore, the method provided by the present disclosure can effectively separate lithium and magnesium, thereby improving the purity of recovered lithium.

Description

Technical Field

[0001] This disclosure belongs to the field of lithium extraction and recovery technology from salt lakes, and specifically relates to a method and apparatus for lithium extraction from salt lakes using a flowing electrode. Background Technology

[0002] In recent years, with the rapid development of new energy vehicles and chemical energy storage, the demand for lithium has surged. Salt lake brines contain enormous lithium resources (accounting for approximately 70% of global lithium reserves), making lithium extraction from salt lakes increasingly important. Various processes have emerged for the development of lithium resources in salt lakes, including evaporation concentration, adsorption, extraction, and membrane separation. Evaporation concentration is only suitable for extracting lithium from solutions with a low magnesium-to-lithium ratio (Mg / Li < 6). Membrane separation is difficult to extract lithium from... + and Na + / K + Separation requires removing the Na from the brine. + and K + Pre-removal results in significant lithium loss. For extraction methods, organic extractants have a certain solubility in brine, posing a potential environmental pollution risk.

[0003] Addressing the challenges of lithium extraction from salt lakes, electrochemical deintercalation has emerged as a promising new method due to its environmental friendliness and high selectivity for lithium. Electrochemical deintercalation utilizes the working principle of aqueous lithium-ion batteries, employing ion sieves with a "memory effect" for lithium ions as electrode materials, salt lake brine as the cathode electrolyte, and a magnesium-free supporting electrolyte as the anolyte, thus forming an electrochemical deintercalation system. Currently, electrochemical deintercalation primarily uses fixed electrodes as lithium ion carriers, resulting in a small contact area between the electrode and the lithium-containing brine, leading to low efficiency in continuous operation. Using flowing electrodes can address some of the problems associated with fixed electrodes, offering convenient operation and enabling continuous lithium extraction, thereby improving operational efficiency.

[0004] However, a common problem with current methods for lithium extraction using flow electrodes is the low purity of the recovered lithium. This significantly limits the application of flow electrodes in lithium extraction. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method and apparatus for lithium extraction from salt lakes using a flowing electrode, which aims to effectively improve the purity of recovered lithium.

[0006] To achieve the above-mentioned objectives of this disclosure, the following technical solutions may be adopted:

[0007] In a first aspect, the scheme provided in this disclosure includes a method for lithium extraction from salt lakes using a flowing electrode, comprising: using a flowing electrode slurry mixed with lithium intercalation / deintercalation active materials as a lithium ion electro-intercalation / deintercalation carrier, and using a flowing electrode slurry mixed with calcium intercalation / deintercalation active materials as a calcium ion electro-intercalation / deintercalation carrier, and extracting lithium from salt lakes through electrochemical principles.

[0008] In some embodiments of this disclosure, a lithium insertion stage and a lithium removal stage are performed sequentially. In the lithium insertion stage, lithium ions are extracted from the lithium-containing brine and enter the lithium-deficient flow electrode slurry to form a lithium-rich flow electrode slurry, while calcium ions are introduced into the lithium-containing brine. In the lithium removal stage, lithium ions are extracted from the lithium-rich flow electrode slurry and enter the lithium-rich recovery solution.

[0009] In the lithium-containing brine, the lithium content is 0.1g / L-5.0g / L and the magnesium content is 100g / L-300g / L.

[0010] In some embodiments of this disclosure, lithium extraction from salt lakes is performed using an electrochemical device having a lithium insertion module and a lithium removal module. The lithium insertion module includes a lithium insertion channel, a lithium-containing brine channel, and a decalcification channel, with the lithium-containing brine channel located between the lithium insertion channel and the decalcification channel. The lithium removal module includes a lithium removal channel, a recovery liquid channel, and a calcium insertion channel, with the recovery liquid channel 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 deintercalation / deintercalation circulation channel. The decalcification channel and the calcium insertion channel are connected to form a calcium ion deintercalation / deintercalation circulation channel. A cation exchange membrane and a current collector are disposed on the inner walls of the lithium insertion channel, the decalcification channel, and the lithium removal channel, and an anion exchange membrane and a current collector are disposed on the inner wall of the calcium insertion channel.

[0011] In some embodiments of this disclosure, the lithium insertion stage includes: placing a lithium-deficient flow electrode slurry in a lithium insertion channel, placing a calcium-rich flow electrode slurry in a decalcification channel, placing lithium-containing brine in a lithium-containing brine channel, connecting the current collector of the lithium insertion channel to a voltage positive electrode and a voltage negative electrode respectively, applying a voltage to allow lithium ions in the lithium-containing brine to enter the lithium insertion channel, forming a lithium-rich flow electrode slurry in the lithium ion deintercalation cycle channel; calcium ions in the calcium-rich flow electrode slurry are desorbed and enter the lithium-containing brine channel, forming a calcium-deficient flow electrode slurry in the calcium ion deintercalation cycle channel.

[0012] In some embodiments of this disclosure, the preparation process of the lithium-deficient flow electrode slurry used in the lithium insertion stage includes: firstly mixing the lithium insertion / de-lithiation 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.

[0013] In some embodiments of this disclosure, the lithium intercalation / deintercalation active material is selected from LiMn2O4 / Li 1-x Mn2O4, LiFePO4 / Li1-x FePO4 and Li2TiO3 / Li 2-x At least one of TiO3.

[0014] In some embodiments of this disclosure, the first salt solution is selected from at least one of sodium chloride solution and potassium chloride solution.

[0015] In some embodiments of this disclosure, the concentration of the first salt solution is 0.5 mol / L to 1.5 mol / L, and the solid content of the lithium-rich slurry is 30% to 40%.

[0016] In some embodiments of this disclosure, the mass ratio of the lithium intercalation / deintercalation active material to the first conductive agent is (85-90):(10-15).

[0017] In some embodiments of this disclosure, the first conductive agent is selected from at least one of conductive carbon black, acetylene black, and carbon nanotubes.

[0018] In some embodiments of this disclosure, the preparation process of the calcium-rich flow electrode slurry includes mixing an intercalation / decalcification active material, a second conductive agent, and a second salt solution.

[0019] In some embodiments of this disclosure, the intercalcification / decalcification 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.

[0020] In some embodiments of this disclosure, the second salt solution is a sodium chloride solution.

[0021] In some embodiments of this disclosure, the concentration of the second salt solution is 0.5 mol / L to 1.5 mol / L, and the solid content in the calcium-rich flow electrode slurry is 30% to 40%.

[0022] In some embodiments of this disclosure, the mass ratio of the decalcified active material to the second conductive agent is (85-90):(10-15).

[0023] In some embodiments of this disclosure, the second conductive agent is selected from at least one of conductive carbon black, acetylene black, and carbon nanotubes.

[0024] In some embodiments of this disclosure, during the lithium intercalation stage, the energizing voltage is controlled to be 0.5V-1.2V, and the energizing time is 4h-8h.

[0025] In some embodiments of this disclosure, the delithiation stage includes: introducing a lithium salt solution into a recovery liquid channel; introducing lithium-rich flow electrode slurry and calcium-deficient flow electrode slurry into a delithiation channel and a calcium intercalation channel through pipes; 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 a voltage positive electrode and a voltage negative electrode, respectively; applying a voltage; causing lithium ions in the lithium-rich flow electrode slurry to be extracted and enter the recovery liquid channel; and inserting calcium ions in the calcium intercalation channel into the calcium-deficient flow electrode slurry.

[0026] In some embodiments of this disclosure, during the delithiation stage, the energizing voltage is controlled to be 0.5V-1.2V, and the energizing time is 4h-8h.

[0027] In some embodiments of this disclosure, during the lithium insertion and delithiation phases, the flow rates of the lithium ion deintercalation circulation channel and the calcium ion deintercalation circulation channel are controlled independently to be 2 mL / min-10 mL / min.

[0028] In some embodiments of this disclosure, the lithium salt solution introduced into the recovery liquid channel is a lithium chloride solution.

[0029] In some embodiments of this disclosure, the concentration of the lithium salt solution is 40 mmol / L to 60 mmol / L.

[0030] In some embodiments of this disclosure, the calcium salt solution introduced into the calcium intercalation channel is a calcium chloride solution.

[0031] In some embodiments of this disclosure, the mass fraction of the calcium salt solution is 60%-70%.

[0032] In some embodiments of this disclosure, the current collectors on the lithium intercalation channel, the decalcification channel, the delithiation channel, and the calcium intercalation channel are all mesh-like.

[0033] In some embodiments of this disclosure, porous materials are used to construct three channels in the lithium insertion module and three channels in the lithium removal module, with the current collector located between the porous material and the corresponding ion exchange membrane.

[0034] In some embodiments of this disclosure, the pore size of the porous material is 20 μm-40 μm.

[0035] In some embodiments of this disclosure, the porous material is selected from at least one of porous resin materials and cordierite.

[0036] In some embodiments of this disclosure, the porous resin material includes polyurethane resin, epoxy resin, and phenolic resin.

[0037] Secondly, the solution provided in this disclosure also includes a lithium extraction device for salt lakes for implementing the method in any of the above embodiments, comprising a lithium intercalation module and a lithium removal module. The lithium intercalation module includes a lithium intercalation channel, a lithium-containing brine channel, and a decalcification channel, with the lithium-containing brine channel located between the lithium intercalation channel and the decalcification channel. The lithium removal module includes a lithium removal channel, a recovery liquid channel, and a calcium intercalation channel, with the recovery liquid channel located between the lithium removal channel and the calcium intercalation channel. The lithium intercalation channel and the lithium removal channel are connected to form a lithium ion deintercalation circulation channel. The 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 decalcification channel, and the lithium removal channel. An anion exchange membrane and a current collector are provided on the inner wall of the calcium intercalation channel.

[0038] This disclosure uses a flow electrode slurry mixed with lithium intercalation / deintercalation active materials as a lithium-ion electro-intercalation / deintercalation carrier and a flow electrode slurry mixed with calcium intercalation / deintercalation active materials as a calcium-ion electro-intercalation / deintercalation carrier. It combines electrochemical principles for lithium extraction from salt lakes. During lithium intercalation, calcium ions are deintercalated into the lithium-containing brine simultaneously with lithium ion insertion. Due to the increased concentration of calcium ions, Ca... 2+ The hydration radius is smaller than Mg 2+ hydration radius, Ca 2+ and Mg 2+ The competition generated when magnesium ions enter the flowing electrode makes it more difficult for them to pass through the ion exchange membrane into the lithium-intercalated slurry, thereby inhibiting the insertion of magnesium ions into the lithium-intercalation / deintercalation active material. Meanwhile, in the lithium-intercalation / deintercalation system, the electrode potential of calcium ions differs significantly from that of lithium ions, thus preventing calcium ions from intercalating into the lithium-intercalation / deintercalation active material. Therefore, the method provided in this disclosure can effectively separate lithium and magnesium, thereby improving the purity of recovered lithium. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram illustrating the process principle of lithium extraction from salt lakes using a flowing electrode, as provided in an embodiment of this disclosure. Detailed Implementation

[0041] The embodiments of this disclosure will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this disclosure. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0042] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein.

[0043] The inventors discovered that the existing methods for lithium extraction from salt lakes using flowing electrodes suffer from low lithium purity primarily because: when lithium ions in the brine enter the lithium intercalation channel through the cation exchange membrane, impurity cations in the brine also enter the channel. In high-magnesium-lithium ratio brine, the magnesium ion content is higher, and the radii of magnesium ions are closer to those of lithium ions, making them more likely to compete with lithium ions for intercalation into the electrode material. This leads to reduced lithium purity, decreased electrode capacity, and consequently, lower extraction efficiency. Therefore, the inventors improved the carrier of the flowing electrode by inhibiting the entry of magnesium ions into the electrode, thereby increasing the purity of the recovered lithium.

[0044] In a first aspect, the scheme provided in this disclosure includes a method for lithium extraction from salt lakes using a flowing electrode, characterized in that it includes: using a flowing electrode slurry mixed with lithium intercalation / deintercalation active materials as a lithium ion electro-intercalation / deintercalation carrier, and using a flowing electrode slurry mixed with calcium intercalation / deintercalation active materials as a calcium ion electro-intercalation / deintercalation carrier, and extracting lithium from salt lakes through electrochemical principles.

[0045] It should be noted that during lithium intercalation, calcium ions are simultaneously extracted into the lithium-containing brine as lithium ions are inserted. Due to the increased concentration of calcium ions, Ca... 2+ The hydration radius is smaller than Mg 2+ hydration radius, Ca 2+ and Mg 2+ The competition generated when magnesium ions enter the flowing electrode makes it more difficult for them to pass through the ion exchange membrane into the lithium-intercalated slurry, thereby inhibiting the insertion of magnesium ions into the lithium-intercalation / deintercalation active material. Meanwhile, in the lithium-intercalation / deintercalation system, the electrode potential of calcium ions differs significantly from that of lithium ions, thus preventing calcium ions from intercalating into the lithium-intercalation / deintercalation active material. Therefore, the method provided in this disclosure can effectively separate lithium and magnesium, thereby improving the purity of recovered lithium.

[0046] In actual operation, such as Figure 1As shown, the method for lithium extraction from a brine lake using a flowing electrode includes a sequential lithium insertion stage and a lithium removal stage. In the lithium insertion stage, lithium ions are extracted from the lithium-containing brine and introduced into a lithium-deficient flowing electrode slurry to form a lithium-rich flowing electrode slurry, while calcium ions are simultaneously introduced into the lithium-containing brine. In the lithium removal stage, lithium ions are extracted from the lithium-rich flowing electrode slurry and introduced into a lithium-rich recovery solution. The lithium-containing brine contains 0.1 g / L–5.0 g / L of lithium and 100 g / L–300 g / L of magnesium.

[0047] Specifically, this may include the following steps:

[0048] S1. Constructing the lithium insertion module and the lithium removal module

[0049] Lithium extraction from salt lakes is carried out using an electrochemical device with a lithium intercalation module and a lithium delithiation module. First, lithium intercalation is performed to allow lithium ions to enter the channel of the lithium intercalation module from the lithium-containing brine. Then, lithium delithiation is performed to allow lithium ions to enter the lithium-rich recovery solution from the channel of the lithium delithiation module.

[0050] The lithium insertion module includes a lithium insertion channel, a lithium-containing brine channel, and a decalcification channel, with the lithium-containing brine channel located between the lithium insertion channel and the decalcification channel. The lithium removal module includes a lithium removal channel, a recovery liquid channel, and a calcium insertion channel, with the recovery liquid channel located between the lithium removal channel and the calcium insertion channel. The lithium insertion channel and the lithium removal channel are connected by pipelines to form a lithium-ion deintercalation / deintercalation circulation channel; the decalcification channel and the calcium insertion channel are connected by pipelines to form a calcium-ion deintercalation / deintercalation circulation channel.

[0051] In other words, both the lithium insertion and delithiation modules contain three channels. In the lithium insertion module, lithium-containing brine is placed in the central lithium-containing brine channel, where the lithium insertion channel contains the under-lithium flowing electrode slurry, and the decalcification channel contains the calcium-rich flowing electrode slurry. In the delithiation module, lithium-rich recovery liquid is placed in the central recovery liquid channel, where the delithiation channel contains the lithium-rich flowing electrode slurry, and the calcium insertion channel contains the under-calcium flowing electrode slurry. During both the lithium insertion and delithiation stages, the lithium-ion deintercalation and calcium-ion deintercalation circulation channels circulate, and the flow rate can be controlled.

[0052] Furthermore, cation exchange membranes and current collectors are disposed on the inner walls of the lithium intercalation channel, decalcification channel, and delithiation channel, while anion exchange membranes and current collectors are disposed on the inner wall of the calcium intercalation channel. The current collector is... Figure 1 Not shown in the figure, in order not to affect the passage of ions, the current collectors on the lithium intercalation channel, decalcification channel, delithiation channel and calcium intercalation channel are all mesh structures, such as titanium mesh, and the shape can be cylindrical.

[0053] In some embodiments of this disclosure, porous materials are used to construct the three channels in the lithium insertion module and the three channels in the lithium removal module. The current collector is located between the porous material and the corresponding ion exchange membrane, with the ion exchange membrane located at the innermost end, in contact with the electrode slurry. Without the action of an electric field, ions will not continue to move and will not permeate through the outer porous material.

[0054] Furthermore, the pore size of the porous material is 20μm-40μm, such as 20μm, 25μm, 30μm, 35μm, 40μm, etc.

[0055] In some embodiments of this disclosure, the porous material is selected from at least one of porous resin materials and cordierite, and may be any one or more of them. Porous resin materials include, but are not limited to, polyurethane resins, epoxy resins, and phenolic resins.

[0056] S2, Lithium Intercalation Stage

[0057] like Figure 1 As shown, a lithium-deficient flow electrode slurry is placed in a lithium insertion channel, a calcium-rich flow electrode slurry is placed in a decalcification channel, and lithium-containing brine is placed in a lithium-containing brine channel. The current collectors of the lithium insertion and decalcification channels are connected to the positive and negative electrodes, respectively. A constant voltage is applied to allow lithium ions from the lithium-containing brine to pass through the porous material and cation exchange membrane into the lithium insertion channel, embedding into the lithium-deficient flow electrode. A lithium-rich flow electrode slurry is formed in the lithium-ion deintercalation cycle channel. Calcium ions in the calcium-rich flow electrode in the decalcification channel are desorbed and enter the lithium-containing brine channel, forming a lithium-deficient flow electrode slurry in the calcium-ion deintercalation cycle channel. The lithium-rich and lithium-deficient flow electrode slurries constitute the starting slurries for the delithiation stage.

[0058] It should be noted that by using decalcification and calcium insertion channels to form a circuit, and lithium insertion and decalcification channels to form a circuit, in the lithium insertion module, while lithium ions are inserted into the lithium insertion channel, calcium ions are extracted from the calcium-intercalated active material and flow into the brine through the porous material towards the negative electrode. Due to the increased concentration of calcium ions, Ca... 2+ The hydration radius is smaller than Mg 2+ The hydration radius of the magnesium ions is relatively small, thus creating competition when the magnesium ions pass through the cation exchange membrane, reducing the permeability of magnesium ions and effectively separating lithium from magnesium, thereby improving the purity of recovered lithium.

[0059] In some embodiments of this disclosure, the preparation process of the lithium-deficient flow electrode slurry used in the lithium insertion stage includes: first mixing the lithium insertion / extraction active material, the first conductive agent, and the first salt solution to form a lithium-rich slurry, and then delithiating the lithium-rich slurry. It is possible to first mix the lithium insertion / extraction active material and the first conductive agent evenly before adding them to the first salt solution to form a uniform slurry, but this is not a limitation.

[0060] Furthermore, the lithium intercalation / deintercalation 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, which 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 intercalation / deintercalation electrode system, LiMn₂O₄ represents a lithium-rich electrode, and Li 1-x Mn2O4 represents the corresponding lithium-deficient electrode.

[0061] Further, 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%. The mass ratio of the lithium intercalation / deintercalation active material to the first conductive agent is (85-90):(10-15). By further controlling the concentration of the slurry, the lithium extraction effect can be improved. Specifically, the concentration of the first salt solution can be 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, etc., the solid content of the lithium-rich slurry can be 30%, 35%, 40%, etc., and the mass ratio of the lithium intercalation / deintercalation active material to the first conductive agent can be 85:15, 86:14, 87:13, 88:12, 89:11, 90:10, etc.

[0062] In some embodiments of this disclosure, the preparation process of the calcium-rich flow electrode slurry includes: mixing a calcium-intercalation / decalcification active material, a second conductive agent, and a second salt solution to form a homogeneous slurry. It is possible to first mix the calcium-intercalation / decalcification active material and the second conductive agent uniformly before adding them to the second salt solution to form a homogeneous slurry, but this is not a limitation.

[0063] In some embodiments of this disclosure, the intercalcification / decalcification 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 the following: ·2,8H₂O, which can be any one or more of the above, where 0 < x < 1. The second salt solution can be a sodium chloride solution, but is not limited thereto.

[0064] In some embodiments of this 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 flow electrode slurry is 30%-40%. The mass ratio of the intercalation / decalcification active material to 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 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, etc., the solid content of the calcium-rich flow electrode slurry can be 30%, 35%, 40%, etc., and the mass ratio of the intercalation / decalcification active material to the second conductive agent can be 85:15, 86:14, 87:13, 88:12, 89:11, 90:10, etc.

[0065] 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.

[0066] In some embodiments of this disclosure, during the lithium intercalation stage, the energizing voltage is controlled to be 0.5V-1.2V, the energizing time is 4h-8h, and the flow rates of the lithium ion deintercalation circulation channel and the calcium ion deintercalation circulation channel are controlled independently to be 2mL / min-10mL / min, so that the lithium extraction process can proceed fully.

[0067] Specifically, during the lithium insertion stage, the control voltage can be 0.5V, 1.0V, 1.2V, etc. The flow rates of the lithium ion insertion / extraction cycle channel and the calcium ion insertion / extraction cycle channel can be the same or unlimited, and can be independently set to 2mL / min, 3mL / min, 5mL / min, 8mL / min, 10mL / min, etc.

[0068] S3, Delithiation Stage

[0069] like Figure 1 As shown, a lithium salt solution is introduced into the recovery liquid channel. The lithium-rich and calcium-deficient flow electrode slurries flow into the delithiation channel and the calcium intercalation channel through pipes. A calcium salt solution is introduced into the calcium intercalation channel. The current collectors of the delithiation channel and the calcium intercalation channel are connected to the positive and negative voltage electrodes, respectively. A constant voltage is applied, and lithium ions in the lithium-rich flow electrode slurry are delithiated and enter the recovery liquid channel to obtain the lithium-rich recovery liquid. Calcium ions in the calcium intercalation channel are intercalated into the calcium-deficient flow electrode slurry. To meet ion balance, chloride ions enter the lithium-rich recovery liquid through the anion exchange membrane.

[0070] In some embodiments of this disclosure, the lithium salt solution introduced into the recovery liquid channel can be a lithium chloride solution, and the calcium salt solution introduced into the calcium intercalation channel can be a calcium chloride solution, but is not limited thereto. The anion species of the lithium salt solution and the calcium salt solution need to be the same. The concentration of the lithium salt solution can 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.

[0071] In some embodiments of this disclosure, during the delithiation stage, the energizing voltage is controlled at 0.5V-1.2V, the energizing time is 4h-8h, and the flow rates of the lithium-ion deintercalation / intercalation circulation channel and the calcium-ion deintercalation / intercalation circulation channel are independently controlled at 2mL / min-10mL / min. By further controlling the operating parameters, lithium ions can be more fully introduced into the lithium-rich recovery solution.

[0072] Specifically, during the delithiation stage, the control voltage can be 0.5V, 1.0V, 1.2V, etc. The flow rates of the lithium ion deintercalation and calcium ion deintercalation circulation channels can be the same or unlimited, and can be independently set to 2mL / min, 3mL / min, 5mL / min, 8mL / min, 10mL / min, etc.

[0073] In some embodiments of this disclosure, the process of lithium extraction from salt lakes may further include: circulating the lithium-deficient and calcium-rich flow electrode slurries formed during the delithiation stage back into the lithium intercalation and decalcification channels through pipelines for 4-8 hours, such as 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.

[0074] This disclosure also provides a lithium extraction device from a salt lake for implementing the above method, including a lithium intercalation module and a lithium removal module. The lithium intercalation module includes a lithium intercalation channel, a lithium-containing brine channel, and a decalcification channel, with the lithium-containing brine channel located between the lithium intercalation channel and the decalcification channel. The lithium removal module includes a lithium removal channel, a recovery liquid channel, and a calcium intercalation channel, with the recovery liquid channel located between the lithium removal channel and the calcium intercalation channel. The lithium intercalation channel and the lithium removal channel are connected to form a lithium ion deintercalation circulation channel. The 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 decalcification channel, and the lithium removal channel. An anion exchange membrane and a current collector are provided on the inner wall of the calcium intercalation channel.

[0075] It should be noted that the specific structures of the lithium insertion module and the lithium removal module are described in the instruction manual above, and will not be repeated here.

[0076] The features and performance of this disclosure will be further described in detail below with reference to embodiments.

[0077] It should be noted that the lithium extraction apparatus used in the following embodiments is as follows: Figure 1 As shown, three channels in the lithium insertion module and three channels in the lithium removal module are constructed using polyurethane resin with a pore size of 30 μm. The channels are cylindrical with a diameter of 30 cm. The current collector is a titanium mesh with a pore size of 1.5 mm and a thickness of 2 mm. The cation exchange membrane and the anion exchange membrane are both homogeneous polyvinylidene fluoride ion exchange membranes with a thickness of 0.5 mm.

[0078] Example 1

[0079] This embodiment provides a method for lithium extraction from salt lakes using a flowing electrode, comprising the following steps:

[0080] (1) A flowing electrode slurry was prepared by adding LiMn2O4 active material and conductive carbon black in a mass ratio of 85:15 to a 1 mol / L NaCl solution. The solid content of the flowing electrode slurry was 35%. The flowing electrode slurry was then delithiated to form a lithium-deficient flowing electrode slurry: the prepared flowing electrode slurry was used as the anode, and an inert carbon electrode was used as the cathode. The delithiation voltage was controlled at 1V until the current density decreased to 0.5 A / m. 2 The lithium-deficient electrode can then be obtained.

[0081] CaV6O 16 • 2.8H2O active material and conductive carbon black were added to a 1 mol / L NaCl solution at a mass ratio of 85:15 to obtain a calcium-rich flow electrode slurry with a solid content of 30%.

[0082] (2) Brine was introduced into a lithium-containing brine channel, and lithium-deficient and calcium-rich flow electrode slurries were introduced into the lithium intercalation and decalcification channels, respectively. The current collectors in the decalcification and lithium intercalation channels were connected to the positive and negative electrodes, respectively. A constant voltage of 0.9V was applied for 6 hours, and the flow rate of the electrode slurries was 5 mL / min. Lithium ions in the brine passed through the porous material and cation exchange membrane into the lithium intercalation channel and intercalated into the lithium-deficient flow electrode to obtain the lithium-rich flow electrode slurry. Calcium ions in the calcium-rich electrode in the decalcification channel were removed, resulting in the lithium-deficient flow electrode slurry.

[0083] (3) A lithium chloride solution with a concentration of 50 mmol / L is introduced into the recovery liquid channel. The lithium-rich flow electrode slurry and the calcium-deficient flow electrode slurry in step (2) flow into the delithiation channel and the calcium intercalation channel through the pipeline at a rate 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 delithiation channel and the current collector in the calcium intercalation channel are connected to the positive and negative electrodes of the voltage, respectively. The constant voltage is controlled at 0.9V and the energizing time is 6h. The lithium ions in the lithium-rich flow electrode are delithiated and enter the recovery liquid to obtain the lithium-rich recovery liquid. The calcium ions in the calcium intercalation channel are intercalated into the calcium-deficient electrode.

[0084] Example 2

[0085] This embodiment provides a method for lithium extraction from salt lakes using a flowing electrode, comprising the following steps:

[0086] (1) A flowing electrode slurry was prepared by adding LiMn2O4 active material and conductive carbon black in a mass ratio of 90:10 to a 1 mol / L NaCl solution. The solid content of the flowing electrode slurry was 30%. The flowing electrode slurry was then delithiated to form a lithium-deficient flowing electrode slurry: the prepared flowing electrode slurry was used as the anode, and an inert carbon electrode was used as the cathode. The delithiation voltage was controlled at 1V until the current density decreased to 0.5 A / m. 2 The lithium-deficient electrode can then be obtained.

[0087] CaV6O 16 • 2.8H2O active material and conductive carbon black were added to a 1 mol / L NaCl solution at a mass ratio of 90:10 to obtain a calcium-rich flow electrode slurry with a solid content of 35%.

[0088] (2) Brine was introduced into a lithium-containing brine channel, and lithium-deficient and calcium-rich flow electrode slurries were introduced into the lithium intercalation and decalcification channels, respectively. The current collectors in the decalcification and lithium intercalation channels were connected to the positive and negative electrodes, respectively. A constant voltage of 1.1V was applied for 4 hours, and the flow rate of the electrode slurries was 8 mL / min. Lithium ions in the brine passed through the porous material and cation exchange membrane into the lithium intercalation channel and intercalated into the lithium-deficient flow electrode to obtain the lithium-rich flow electrode slurry. Calcium ions in the calcium-rich electrode in the decalcification channel were removed, resulting in the lithium-deficient flow electrode slurry.

[0089] (3) A lithium chloride solution with a concentration of 50 mmol / L is introduced into the recovery liquid channel. The lithium-rich flow electrode slurry and the calcium-deficient flow electrode slurry in step (2) flow into the delithiation channel and the calcium intercalation channel through the pipeline at a rate 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 delithiation channel and the current collector in the calcium intercalation channel are connected to the positive and negative electrodes of the voltage, respectively. The constant voltage is controlled at 1.1V and the energizing time is 4h. The lithium ions in the lithium-rich flow electrode are delithiated and enter the recovery liquid to obtain the lithium-rich recovery liquid. The calcium ions in the calcium intercalation channel are intercalated into the calcium-deficient electrode.

[0090] (4) The lithium-deficient and calcium-rich flow electrode slurries from step (3) are recycled back into the lithium insertion channel and the decalcification channel through pipelines for 3 hours.

[0091] Example 3

[0092] This embodiment provides a method for lithium extraction from salt lakes using a flowing electrode, comprising the following steps:

[0093] (1) A flowing electrode slurry was prepared by adding LiMn2O4 active material and conductive carbon black in a mass ratio of 85:15 to a 1 mol / L NaCl solution. The solid content of the flowing electrode slurry was 40%. The flowing electrode slurry was then delithiated to form a lithium-deficient flowing electrode slurry: the prepared flowing electrode slurry was used as the anode, and an inert carbon electrode was used as the cathode. The delithiation voltage was controlled at 1V until the current density decreased to 0.5 A / m. 2 The lithium-deficient electrode can then be obtained.

[0094] CaV6O 16 • 2.8H2O active material and conductive carbon black were added to a 1 mol / L NaCl solution at a mass ratio of 85:15 to obtain a calcium-rich flow electrode slurry with a solid content of 40%.

[0095] (2) Brine was introduced into a lithium-containing brine channel, and lithium-deficient and calcium-rich flow electrode slurries were introduced into the lithium intercalation channel and decalcification channel, respectively. The current collectors in the decalcification channel and the lithium intercalation channel were connected to the positive and negative electrodes, respectively. A constant voltage of 0.7V was applied for 8 hours, and the flow rate of the electrode slurry was 2 mL / min. Lithium ions in the brine passed through the porous material and cation exchange membrane into the lithium intercalation channel and intercalated into the lithium-deficient flow electrode to obtain the lithium-rich flow electrode slurry. Calcium ions in the calcium-rich electrode in the decalcification channel were removed, resulting in the lithium-deficient flow electrode slurry.

[0096] (3) A lithium chloride solution with a concentration of 50 mmol / L is introduced into the recovery liquid channel. The lithium-rich flow electrode slurry and the calcium-deficient flow electrode slurry in step (2) flow into the delithiation channel and the calcium intercalation channel through the pipeline at a rate 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 delithiation channel and the current collector in the calcium intercalation channel are connected to the positive and negative electrodes of the voltage, respectively. The constant voltage is controlled at 0.7V and the energizing time is 8h. The lithium ions in the lithium-rich flow electrode are delithiated and enter the recovery liquid to obtain the lithium-rich recovery liquid. The calcium ions in the calcium intercalation channel are intercalated into the calcium-deficient electrode.

[0097] (4) The lithium-deficient and calcium-rich flow electrode slurries from step (3) are recycled back into the lithium insertion channel and the decalcification channel through pipelines for 9 hours.

[0098] Example 4

[0099] This embodiment provides a method for lithium extraction from salt lakes using a flowing electrode. The difference from Embodiment 1 is that the lithium intercalation / deintercalation active material is LiFePO4, and the calcium intercalation / deintercalation active material is Ca. x CuHCF active material.

[0100] Example 5

[0101] This embodiment provides a method for lithium extraction from salt lakes using a flowing electrode. The difference from Embodiment 1 is that the lithium extraction and delithiation voltage is 2V.

[0102] Example 6

[0103] This embodiment provides a method for lithium extraction from salt lakes using a flowing electrode, which differs from Embodiment 1 in that the lithium extraction and delithiation voltage is 0.3V.

[0104] Comparative Example

[0105] This embodiment provides a method for lithium extraction from salt lakes using a flowing electrode. The difference from Embodiment 1 is that the active material for calcium insertion / extraction in the calcium insertion / extraction 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 in Embodiment 1.

[0106] Test case

[0107] The lithium extraction effects of the test examples and comparative examples are shown in Table 1.

[0108] Test method: The lithium ion concentration and magnesium ion concentration before and after the reaction, as well as the purity of the recovered lithium, were measured using an inductively coupled plasma atomic emission spectrometer (ICP), as shown in Table 1.

[0109] Table 1. Lithium ion concentration and magnesium ion concentration before and after the reaction, and purity of recovered lithium.

[0110]

[0111]

[0112] As can be seen from the examples and comparative examples, the lithium recovery rate in the examples is greater than 90%. The concentration of magnesium ions in the recovered solution of Example 1 decreased by at least 0.78 g / L compared to the comparative example, indicating a reduction in impurities and an increase in lithium ion purity. This demonstrates that the competitive effect between calcium and magnesium ions effectively prevents magnesium ions from entering the lithium intercalation channel during lithium extraction, thus improving the lithium extraction efficiency. Comparing Example 1 and Examples 5-6, it can be seen that excessively high lithium extraction voltage leads to side reactions and reduces lithium extraction efficiency, while excessively low lithium extraction voltage results in a low reaction rate and also reduces lithium extraction efficiency.

[0113] Industrial applicability

[0114] This disclosure utilizes a flowing electrode slurry containing lithium-intercalation / deintercalation active materials as a lithium-ion electro-intercalation / deintercalation support and a flowing electrode slurry containing calcium-intercalation / deintercalation active materials as a calcium-ion electro-intercalation / deintercalation support, combining electrochemical principles for lithium extraction from salt lakes. The salt lake lithium extraction device of this disclosure can be obtained by simply adjusting existing flowing electrodes used for lithium extraction from salt lakes. It is easy to operate, can effectively separate lithium and magnesium, thereby improving the purity of recovered lithium, and has excellent industrial applicability.

Claims

1. A method for lithium extraction from salt lakes using a flowing electrode, characterized in that, include: Using a flow electrode slurry mixed with lithium intercalation / deintercalation active materials as a lithium-ion electro-intercalation / deintercalation carrier and a flow electrode slurry mixed with calcium intercalation / deintercalation active materials as a calcium-ion electro-intercalation / deintercalation carrier, lithium extraction from salt lakes is carried out through electrochemical principles. The lithium extraction process from the salt lake includes a lithium insertion stage and a lithium removal stage performed sequentially. In the lithium insertion stage, lithium ions are extracted from the lithium-containing brine and enter a lithium-deficient flow electrode slurry to form a lithium-rich flow electrode slurry, while calcium ions are introduced into the lithium-containing brine. In the lithium removal stage, lithium ions are extracted from the lithium-rich flow electrode slurry and enter a lithium-rich recovery solution.

2. The method according to claim 1, characterized in that... In the lithium-containing brine, the lithium content is 0.1 g / L-5.0 g / L and the magnesium content is 100 g / L-300 g / L.

3. The method according to claim 1 or 2, characterized in that, Lithium extraction from salt lakes is performed using an electrochemical device with a lithium insertion module and a lithium removal module. The lithium insertion module includes a lithium insertion channel, a lithium-containing brine channel, and a decalcification channel, with the lithium-containing brine channel located between the lithium insertion channel and the decalcification channel. The lithium removal module includes a lithium removal channel, a recovery liquid channel, and a calcium insertion channel, with the recovery liquid channel 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 deintercalation / deintercalation circulation channel. The decalcification channel and the calcium insertion channel are connected to form a calcium-ion deintercalation / deintercalation circulation channel. A cation exchange membrane and a current collector are disposed on the inner walls of the lithium insertion channel, the decalcification channel, and the lithium removal channel. An anion exchange membrane and a current collector are disposed 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 flow electrode slurry in the lithium insertion channel, placing a calcium-rich flow electrode slurry in the decalcification channel, placing lithium-containing brine in the lithium-containing brine channel, connecting 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, forming a lithium-rich flow electrode slurry in the lithium ion deintercalation cycle channel; calcium ions in the calcium-rich flow electrode slurry are deintercalated into the lithium-containing brine channel, forming a calcium-deficient flow electrode slurry in the calcium ion deintercalation cycle channel.

5. The method according to claim 4, characterized in that, The preparation process of the lithium-deficient flow electrode slurry used in the lithium insertion stage includes: firstly, mixing the lithium insertion / de-lithiation 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 intercalation / deintercalation active material is selected from LiMn2O4 / Li1 x Mn2O4, LiFePO4 / Li1 x FePO4 and Li2TiO3 / Li2 x At least one of TiO3.

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

8. The method according to claim 5, 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 claim 5, characterized in that, The mass ratio of the lithium intercalation / deintercalation active material to the first conductive agent is (85-90):(10-15).

10. The method according to claim 5, 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 claim 4, characterized in that, The preparation process of the calcium-rich flow electrode slurry includes mixing the intercalated / decalcified active material, the second conductive agent, and the second salt solution.

12. The method according to claim 11, characterized in that, The intercalcification-decalcification active substance 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, characterized in that, The second salt solution is a sodium chloride solution.

14. The method according to claim 11, 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 flow electrode slurry is 30%-40%.

15. The method according to claim 11, characterized in that, The mass ratio of the intercalated / decalcified active material to the second conductive agent is (85-90):(10-15).

16. The method according to claim 11, 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 claim 4, characterized in that, During the lithium intercalation stage, the energizing voltage is controlled to be 0.5V-1.2V, and the energizing time is 4h-8h.

18. The method according to claim 4, characterized in that, The delithiation stage includes: introducing a lithium salt solution into the recovery liquid channel; the lithium-rich flow electrode slurry and the calcium-deficient flow electrode slurry flowing into the delithiation channel and the calcium intercalation channel through pipes; 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 and negative voltage electrodes respectively; applying a voltage; causing lithium ions in the lithium-rich flow electrode slurry to be released into the recovery liquid channel; and embedding calcium ions in the calcium intercalation channel into the calcium-deficient flow electrode slurry.

19. The method according to claim 18, characterized in that, During the delithiation stage, the energizing voltage is controlled at 0.5V-1.2V, and the energizing time is 4h-8h.

20. The method according to claim 4, characterized in that, During the lithium insertion and delithiation phases, the flow rates of the lithium ion deintercalation circulation channel and the calcium ion deintercalation circulation channel are independently controlled to be 2 mL / min-10 mL / min.

21. The method according to claim 18, characterized in that, The lithium salt solution introduced into the recovery liquid channel is a lithium chloride solution.

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

23. The method according to claim 18, characterized in that, The calcium salt solution introduced into the calcium intercalation channel is a calcium chloride solution.

24. The method according to claim 18, characterized in that, The calcium salt solution has a mass fraction of 60%-70%.

25. The method according to claim 3, characterized in that, The current collectors on the lithium intercalation channel, the decalcification channel, the delithiation channel, and the calcium intercalation channel are all mesh-like.

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 20μm-40μm.

28. The method according to claim 26, characterized in that, The porous material is selected from at least one of porous resin materials 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 lithium extraction apparatus for brine lakes for implementing the method according to any one of claims 1-29, characterized in that, The system includes a lithium insertion module and a lithium removal module. The lithium insertion module includes a lithium insertion channel, a lithium-containing brine channel, and a decalcification channel, with the lithium-containing brine channel located between the lithium insertion channel and the decalcification channel. The lithium removal module includes a lithium removal channel, a recovery liquid channel, and a calcium insertion channel, with the recovery liquid channel 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 deintercalation / deintercalation circulation channel. The decalcification channel and the calcium insertion channel are connected to form a calcium-ion deintercalation / deintercalation circulation channel. A cation exchange membrane and a current collector are provided on the inner walls of the lithium insertion channel, the decalcification channel, and the lithium removal channel. An anion exchange membrane and a current collector are provided on the inner wall of the calcium insertion channel.

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