A device for extracting lithium from salt lake brine and a method of use

Abstract

This invention relates to an apparatus and method for lithium extraction from salt lake brine. The invention includes: a lithium electrode, a sodium electrode, an anion exchange membrane, a storage battery, a lithium chloride purification tank, and a salt lake brine tank. The anion exchange membrane divides the lithium chloride purification tank into L-chambers and N-chambers. The invention also includes a method for using the apparatus. The advantages of this invention are: utilizing the positive electrode material of a lithium battery to achieve specific adsorption of lithium ions; it does not have stringent requirements on lithium ion concentration and magnesium-to-lithium ratio; it can directly purify lithium ions from high magnesium-to-lithium ratio salt lake brine without concentration or other complex pretreatment; the entire process is energy-efficient and highly effective; simultaneously, the lithium ion desorption process is simple, does not require strong acids or alkalis, and does not generate waste liquid, making it environmentally friendly; the lithium chloride solution obtained by coupling the anion exchange membrane has high purity and can be directly concentrated using mature reverse osmosis technology to increase the lithium chloride concentration, laying the foundation for the subsequent production of high-purity lithium products.

Description

Technical Field

[0001] This invention relates to a mixture separation device and method, specifically a lithium extraction device and method from salt lake brine. Background Technology

[0002] Since Sony successfully commercialized lithium-ion batteries, their high energy density and excellent cycle performance have dramatically increased lithium's importance in modern industry, making it a strategic metal for national economy and defense. According to the U.S. Geological Survey in 2021, global proven lithium reserves are approximately 86 million tons, mainly distributed in salt lake brines and hard rocks, with salt lake brines accounting for over 70% of the lithium resources. Currently, lithium extraction methods from salt lakes primarily include precipitation, adsorption, and membrane separation.

[0003] The precipitation method first involves evaporating and concentrating the brine from salt lakes to remove impurities such as calcium, magnesium, and boron. Then, a precipitant is added to precipitate lithium, using methods such as carbonate precipitation and aluminate precipitation. However, this process is only suitable for lithium extraction from salt lake brines with low magnesium-to-lithium ratios. When used for salt lake brines with high magnesium-to-lithium ratios in my country, it requires a large amount of precipitant, resulting in relatively high costs. Furthermore, this process is lengthy, has a low lithium recovery rate, and generates a large amount of waste residue, posing a significant environmental threat.

[0004] The adsorption method first uses functional materials with selective adsorption properties for lithium ions, such as ion sieve adsorbents, to capture lithium ions through sufficient contact with brine from salt lakes. After adsorption saturation, the lithium ions in the adsorbent are eluted with water or an eluent, thereby separating the lithium ions from other ions. This method is suitable for brine from salt lakes with a high magnesium-to-lithium ratio, and the process is relatively simple, with good selectivity, high recovery rate, low cost, and easy to scale up. However, the core lithium ion adsorbent in this process currently has a relatively small adsorption capacity, and the elution process is relatively complex, generating a large amount of waste acid.

[0005] Membrane separation is a novel method for lithium-ion purification, including nanofiltration, electrodialysis, and membrane adsorption. Nanofiltration membranes possess excellent separation performance for both multivalent and monovalent ions, making them suitable for magnesium-lithium separation in lithium extraction from salt lake brine. However, salt lake brine has high salinity and contains a high concentration of organic matter, making direct nanofiltration prone to membrane clogging and reduced flux. Therefore, brine dilution is necessary to lower its concentration. Consequently, large-scale application of nanofiltration membrane separation technology for lithium extraction from salt lake brine still has a long way to go, requiring the development of nanofiltration membrane materials with high selectivity and stable flux.

[0006] As a major consumer of lithium resources, my country's dependence on imported lithium exceeds 70%. This is mainly because my country's lithium resources are commonly found in the brine of salt lakes in the western region, where low lithium concentration and high magnesium-to-lithium ratios significantly increase the difficulty of lithium extraction. Therefore, developing an efficient method for lithium extraction from salt lake brine is of great significance for ensuring the sustainable utilization of my country's lithium resources. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides an apparatus and method for lithium extraction from salt lake brine.

[0008] The present invention provides an apparatus for lithium extraction from salt lake brine, comprising: a lithium battery positive electrode, a lithium battery negative electrode, an anion exchange membrane, an electrolyte tank and a brine tank, wherein the anion exchange membrane divides the electrolyte tank into an L-chamber and an N-chamber.

[0009] Preferably, the positive electrode of the lithium battery can be one of lithium cobalt oxide, lithium manganese oxide, and lithium iron phosphate.

[0010] Preferably, the negative electrode of the lithium battery can be one of graphite or carbon black;

[0011] This invention provides a method for lithium extraction from salt lake brine, using the aforementioned apparatus for lithium extraction from salt lake brine, characterized by comprising the following steps:

[0012] S1. Add pure water to chamber L, add NaCl aqueous solution to chamber N, and add the brine from the salt lake that needs to be purified to the brine tank.

[0013] S2. Insert the positive and negative terminals of the lithium battery into chambers L and N respectively, and connect them to the positive and negative terminals of the power supply respectively; at this time, it is in charging mode, and due to the effect of the electric field, Li + The Na+ ions migrate from the positive electrode to the negative electrode of the lithium battery, but due to the obstruction of the anion exchange membrane, they can only exist in the pure water of the L chamber; the Na+ ions in the N chamber... + It then migrates to the negative electrode of the lithium battery, while Cl... - They then migrate through the anion exchange membrane into the L chamber, forming a LiCl solution;

[0014] S3, waiting for Li + After the migration is complete, disconnect the power supply, connect the positive and negative terminals of the lithium battery, and simultaneously immerse them in the brine of the salt lake; at this time, it is in discharge mode, and the Na in the negative terminal of the lithium battery... + Migrating to the brine of the salt lake, and the Li in the salt lake brine + Migrating to the positive electrode of a lithium battery, because the lattice in the positive electrode of a lithium battery only affects Li + It has adsorption capabilities, so other cations cannot enter the lithium-ion cathode;

[0015] S4, Li to be adsorbed at the positive electrode of lithium battery +If saturation occurs, cycle through step S2, inserting the positive and negative electrodes of the lithium battery into chambers L and N respectively, and connecting them to the positive and negative terminals of the power supply. At this point, the Li₂ adsorbed from the brine... + The pure water released from the positive electrode of the lithium battery into the L chamber is circulated repeatedly, thereby achieving the purification of LiCl in the salt lake brine.

[0016] Beneficial effects:

[0017] Compared with existing technologies, this invention utilizes the positive electrode material of lithium batteries to achieve specific adsorption of lithium ions. It does not have stringent requirements on the lithium ion concentration and magnesium-lithium ratio in salt lake brines, and can be directly used for lithium ion purification in most salt lake brines with high magnesium-lithium ratios in China. No prior concentration or other treatment is required, and it has the advantages of low energy consumption and high efficiency. At the same time, the elution process is simple, does not require the use of strong acids or alkalis, and does not generate waste liquid, making it environmentally friendly. The lithium chloride solution obtained by elution has high purity and can be directly concentrated using mature reverse osmosis technology to increase the lithium chloride concentration, which is convenient for later use. Attached Figure Description

[0018] Figure 1 Schematic diagram of the lithium chloride purification tank

[0019] Figure 2 Schematic diagram of the structure of the salt lake brine tank

[0020] Figure 3 Schematic diagram of the lithium ion release process in a lithium chloride purification tank.

[0021] Figure 4 Schematic diagram of the lithium ion extraction process in salt lake brine tanks. Detailed Implementation

[0022] The implementation process of the present invention will be described in detail below with reference to the accompanying drawings:

[0023] Example 1

[0024] like Figure 1 As shown, an apparatus for lithium extraction from salt lake brine includes a lithium electrode, a sodium electrode, an anion exchange membrane, a battery, a lithium chloride purification tank, and a salt lake brine tank. The lithium electrode is a lithium iron phosphate electrode, the sodium electrode is a carbon black electrode, and the anion exchange membrane divides the lithium chloride purification tank into L-chambers and N-chambers.

[0025] Example 2

[0026] The apparatus for lithium extraction using the above-described salt lake brine, as shown in Example 1, includes the following steps:

[0027] S1. Add 1L of pure water to chamber L, add 1L of 1wt% NaCl aqueous solution to chamber N, and add 5L of brine from the salt lake to be purified to the brine tank. At this time, Li +The concentration was 0.2 g / L;

[0028] S2. Insert the lithium electrode and sodium electrode into chamber L and N respectively, and connect them to the positive and negative terminals of the power supply respectively; at this time, due to the effect of the electric field, Li + The sodium ion migrates from the lithium electrode to the sodium electrode, but due to the obstruction of the anion exchange membrane, it can only exist in the pure water of the L chamber; the Na+ in the N chamber... + It then migrates to the sodium electrode, while Cl... - It then migrates through the anion exchange membrane into the L chamber, forming a LiCl solution; after 10 minutes, Li + After the relocation is complete, disconnect the power. The implementation process is as follows: Figure 3 As shown;

[0029] S3. Connect the lithium electrode and sodium electrode and simultaneously insert them into the brine of the salt lake. The structure of the brine tank is shown in the attached figure. Figure 2 As shown; at this time, it is in discharge mode, and the Na in the sodium electrode + Migrating to the brine of the salt lake, and the Li in the salt lake brine + Migrating to the lithium electrode, because the lattice in the lithium electrode only affects Li + It has an adsorption function, so other cations cannot enter the lithium electrode; 5L of fresh brine is replaced every 2 minutes, and adsorption is completed after a total of 10 minutes. The entire process is shown in the attached figure. Figure 4 As shown;

[0030] S4. Repeat steps S2 and S3 four times to obtain Li. + The purification of LiCl was completed using a LiCl aqueous solution with a concentration of 22.5 g / L.

[0031] In this embodiment, the positive electrode of the lithium battery is one of lithium cobalt oxide, lithium manganese oxide, or lithium iron phosphate, and the negative electrode of the lithium battery is one of graphite or carbon black. Both of these methods can achieve the desired effect on the lithium battery in this embodiment. + concentrate.

Claims

1. A method of using a lithium extraction apparatus for salt lake brine, the apparatus comprising: Power supply, anion exchange membrane, electrolyte tank; The positive terminal of the power supply is connected to the positive terminal of the lithium battery, and the negative terminal of the lithium battery is connected to the negative terminal of the power supply; an anion exchange membrane divides the electrolyte tank into an L-chamber and an N-chamber; the positive terminal of the lithium battery is placed in the L-chamber, and the negative terminal of the lithium battery is placed in the N-chamber; the positive terminal of the lithium battery is lithium iron phosphate; the negative terminal of the lithium battery is carbon black; the feature is that it includes the following steps: S1. Add pure water to chamber L, add NaCl aqueous solution to chamber N, and add the brine from the salt lake to be purified to the brine tank; the amount of pure water added is 1L; the amount of NaCl aqueous solution added is 1L, and the concentration of the NaCl aqueous solution is 1wt%; the amount of brine from the salt lake added is 5L; in step S1, Li + The concentration was 0.2 g / L; S2. Insert the positive and negative terminals of the lithium battery into chambers L and N respectively, and connect them to the positive and negative terminals of the power supply respectively. After the power is turned on, due to the electric field, Li + Migrating from the positive electrode to the negative electrode of a lithium battery, Li is blocked by the anion exchange membrane. + Na can only exist in pure water in chamber L; Na in chamber N + Migrating towards the negative electrode of the lithium battery, while Cl - It then migrates through the anion exchange membrane into the L chamber, forming a LiCl solution; the Li + The migration will be completed in 10 minutes. S3, waiting for Li + After the migration is complete, disconnect the power supply and connect the positive and negative terminals of the lithium battery with a wire, then simultaneously insert them into the brine of the salt lake; at this time, it is in discharge mode, and the Na in the negative terminal of the lithium battery... + Migrating to the brine of the salt lake, and the Li in the salt lake brine + Migrating to the positive electrode of a lithium battery, because the lattice in the positive electrode of a lithium battery only affects Li + It has an adsorption function, so other cations cannot enter the lithium-ion cathode; 5L of fresh salt lake brine is replaced every 2 minutes, and adsorption is completed after a total of 10 minutes; S4, Li to be adsorbed at the positive electrode of lithium battery + If saturation occurs, cycle through step S2, inserting the positive and negative electrodes of the lithium battery into chambers L and N respectively, and connecting them to the positive and negative terminals of the power supply. At this point, the Li₂ adsorbed from the brine... + The pure water released from the positive electrode of a lithium battery into chamber L is circulated repeatedly to purify LiCl in the brine of the salt lake; the number of cycles is 4; the LiCl solution is purified. + The concentration was 22.5 g / L.

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