CN-121974379-A - Method and device for extracting lithium

Abstract

The invention belongs to the technical field of lithium salt purification, and discloses a method and a device for extracting lithium. The method comprises the steps of providing a lithium-containing mixed salt, contacting the lithium-containing mixed salt with an organic solvent to form a lithium-salt-rich organic solution and a mixed system containing undissolved sodium salt solids, and performing interfacial evaporation on the mixed system to remove part of the organic solvent, promote precipitation of the sodium salt, and simultaneously enrich the lithium salt in a residual liquid phase to separate the lithium salt from the sodium salt. The method provided by the invention can realize the high-efficiency and high-selectivity separation of lithium salt and sodium salt.

Inventors

• DENG HONGBING
• SHI LEI
• DONG XIANGYANG

Assignees

• 武汉大学

Dates

Publication Date

20260505

Application Date

20260122

Claims (10)

1. 1. A method of extracting lithium, comprising: Providing a lithium-containing mixed salt; Contacting the lithium-containing mixed salt with an organic solvent to form a lithium salt-rich organic solution and a mixed system containing undissolved sodium salt solids; And performing interfacial evaporation on the mixed system to remove part of the organic solvent, promoting precipitation of the sodium salt, and simultaneously enriching the lithium salt in a residual liquid phase to realize separation of the lithium salt and the sodium salt.
2. 2. The method of claim 1, wherein the lithium-containing mixed salt comprises at least one of seawater, salt lake brine, geothermal brine, oilfield brine, industrial byproduct brine, and a product after concentration and/or preliminary separation.
3. 3. The method according to claim 1, wherein the organic solvent comprises at least one of alcohols, ketones, nitriles, preferably the organic solvent comprises at least one of methanol, ethanol, acetone.
4. 4. The method of claim 3, wherein the organic solvent further comprises at least one of ethers, esters, halogenated hydrocarbons.
5. 5. A method according to any one of claims 1 to 3, wherein the mass ratio of the organic solvent to the lithium-containing mixed salt is 1 (0.01-100), preferably 1 (0.35-5).
6. 6. The method according to any one of claims 1 to 3, wherein the mass ratio of the lithium element to the sodium element in the mixed system is (1.6X10 -7 -1.6×10 3 ): 1.
7. 7. The method according to any one of claims 1-3, wherein the interfacial evaporation is performed under energy drive, the energy comprising ambient energy and/or external energy, wherein the ambient energy comprises one or more of solar energy, ambient thermal energy, air convection energy, and the external energy comprises one or more of thermal energy, mechanical energy.
8. 8. A lithium extraction device, comprising: a raw material supply unit for supplying a lithium-containing mixed salt and an organic solvent; the mixing and dissolving unit is connected with the raw material supply unit and is used for mixing and contacting the lithium-containing mixed salt with an organic solvent to form an organic solution rich in lithium salt and a mixed system containing undissolved sodium salt solids; The interface evaporation separation unit is connected with the mixed dissolution unit and comprises an evaporation interface for receiving the mixed system, removing part of the organic solvent through interface evaporation to promote precipitation of sodium salt, and simultaneously enriching the lithium salt in a residual liquid phase to realize separation of the lithium salt and the sodium salt.
9. 9. The apparatus of claim 8, wherein the interfacial evaporation separation unit further comprises: The evaporation interface is arranged on the surface or inside the evaporation body; the liquid inlet part is connected with the mixing and dissolving unit and is used for conveying the mixed system to the evaporation interface; And a collection part for collecting the liquid phase enriched with the lithium salt and/or lithium salt crystals.
10. 10. The device of claim 8, wherein the evaporation interface is a solid surface having an extended surface area, the solid surface being made of at least one of a metal, a ceramic, a composite, and a polymer, and the solid surface having a structural morphology comprising at least one of a planar surface, a textured surface, a porous structure, and an array of fiber bundles.

Description

Method and device for extracting lithium Technical Field The invention belongs to the technical field of lithium salt purification, and particularly relates to a lithium extraction method and a lithium extraction device. Background The process of electrification exacerbates the worldwide demand for lithium resources, seawater being a potential approach to solving this supply and demand problem as a rich lithium reservoir. However, the lithium content in seawater is extremely low, and the concentration of coexisting ions such as sodium is far higher than that of lithium, and the concentration difference between the two is usually several orders of magnitude, so that the high-selectivity enrichment of lithium in a complex salt background is very difficult to realize. In addition, the seawater system has a plurality of ion types and high background salinity, and the phenomena of competition and coprecipitation among ions are common, so that the separation difficulty is further increased. Limited by the inherent characteristic of low lithium and high sodium, seawater lithium extraction not only requires higher selectivity, but also needs to be compatible with engineering constraints of low cost, low energy consumption, large-scale and the like. At present, common ways of seawater concentration and salt separation mainly depend on evaporation crystallization processes of an evaporation pond, but in a water system, solubility difference of sodium chloride and lithium chloride is limited, co-precipitation easily occurs in the evaporation crystallization process, and high-purity lithium salt is difficult to obtain. Meanwhile, although the direct lithium extraction technology such as adsorption, electrochemistry, membrane separation or solvent extraction can improve the selectivity to a certain extent, the problems of higher energy consumption and reagent consumption, complex device and process, high maintenance cost, insufficient suitability for an ultra-low concentration system, higher environmental burden and the like often exist. Therefore, the development of a selective lithium extraction strategy which is low in cost, low in complexity and suitable for a low-lithium high-sodium system has important significance. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present invention is to provide a method and an apparatus for extracting lithium, which can realize efficient and high-selectivity separation of lithium salt and sodium salt. In a first aspect of the invention, the invention provides a lithium extraction method, which comprises the steps of providing a lithium-containing mixed salt, contacting the lithium-containing mixed salt with an organic solvent to form a lithium-salt-rich organic solution and a mixed system containing undissolved sodium salt solids, and performing interfacial evaporation on the mixed system to remove part of the organic solvent, promote precipitation of the sodium salt, and simultaneously enrich the lithium salt in a residual liquid phase to separate the lithium salt from the sodium salt. According to the method of the above embodiment of the present invention, after the lithium-containing mixed salt is contacted with the organic solvent, since the lithium salt has higher solubility in the organic solvent than the sodium salt, the lithium salt is preferentially dissolved into the liquid phase, whereas the sodium salt exists mainly in a solid form, and only a small amount of the sodium salt is dissolved. Subsequently, part of the organic solvent is removed by interfacial evaporation, the sodium salt is further crystallized and separated out, and the lithium salt is gradually enriched in the residual liquid phase, so that the separation of the two is realized. The method provided by the invention has the advantages of simple process, low energy consumption and high separation efficiency, and can realize the high-efficiency and high-selectivity separation of lithium salt and sodium salt. In addition, the method of the above embodiment of the present invention may further have the following additional technical features: In some embodiments of the present invention, the lithium-containing mixed salt comprises a concentrated and/or primarily separated product of at least one of seawater, salt lake brine, geothermal brine, oilfield brine, and industrial byproduct brine. Thus, the lithium salt and the sodium salt can be separated efficiently and selectively. In some embodiments of the present invention, the organic solvent comprises at least one of alcohols, ketones, nitriles, preferably at least one of methanol, ethanol, acetone. Thus, the lithium salt and the sodium salt can be separated efficiently and selectively. In some embodiments of the invention, the organic solvent further comprises at least one of ethers, esters, halogenated hydrocarbons. Thus, the lithium salt and t