Comprehensive utilization method of lithium-containing waste fluids

Abstract

The invention discloses a comprehensive utilization method of lithium-containing waste fluids. Lithium carbonate washing water in lithium carbonate preparation technology, pyrolysis mother-liquor generated during high-purity lithium carbonate preparation by a carbonization-decomposition method, or a liquid with similar composition of the lithium carbonate washing water or the pyrolysis mother-liquor is used as a raw material. The raw material undergoes primary or secondary electrodialysis treatment, and a cation exchange membrane and an anion exchange membrane are utilized. On one hand, Li<+> is concentrated and enriched so as to obtain a lithium-rich concentrate with Li<+> content being 10g / L-20g / L; and on the other hand, water produced by primary desalination can be purified so as to obtain deionized water with TDS value being lower than 20mg / L for reuse. By combination of electrodialysis and reverse osmosis, a closed-cycle technology is formed. Then, comprehensive yield of Li<+> is close to 100%, and water loss is zero. Thus, Li<+> and water in the lithium carbonate washing water and the solution with the similar composition are synchronously and completely recovered.

Description

technical field [0001] The invention belongs to the technical field of solution separation and purification, and in particular relates to a comprehensive utilization method of lithium-containing waste liquid. Background technique [0002] As an important strategic resource for human beings in the new era, new energy lithium metal has been widely used in many fields such as lithium battery, glass and ceramics, lithium-based grease, refrigeration, medicine, metallurgy and nuclear industry. In recent years, the explosive growth of lithium batteries in the application fields of electronic products, new energy vehicles and large-scale energy storage has driven the development of domestic and foreign Li batteries. 2 CO 3 , LiCl, LiOH and other basic lithium saline products demand rapid development. [0003] Lithium mainly exists in nature in two forms of solid ore and liquid ore, among which solid ore lithium resources include spodumene, lithium feldspar, lepidolite, lithium pho...

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Problems solved by technology

[0006] Although there are some in the prior art that lithium-containing feed liquid (generally brine) is processed, Li + reports, such as: (1) a method for adsorbing and extracting lithium chloride from a solution, in which the eluent is used repeatedly to remove Li in the eluate + Increase the concentration of Ca to more than 1.6g / L, and then use cation exchange resin to remove Ca 2+ , Mg 2+ , and finally use electrodialysis to remove the Li in the eluate + The content of the electrodialysis desalination product is concentrated to more than 16g / L, and the electrodialysis desalination water is returned to the desorption section as desorption water; however, this method has a long process and involves multiple steps such as adsorption, ion exchange, and electrodialysis, and the reused desalination solution contains The salt content is high, and it cannot be used as fresh water or deionized water; (2) A technology that uses nanofiltration membranes to separate magnesium and lithium, and the lithium-rich solution obtained by nanofiltration is reverse osmosis to realize Li + Concentration, the fresh water obtained by reverse osmosis is reused in the stock solution dilution process; but this method is limited by the osmotic pressure of concentrated water, and reverse osmosis has a negative effect on Li + The actual degree of concentration is much lower than 5g / L, and the fresh water recovered by reverse osmosis only occupies a low proportion, and the Ca in the raw water of reverse osmosis 2+ and SO 4 2- It is easy to crystallize and precipitate on the membrane surface, shortening the service life of the membrane; (3) a method for obtaining concentrated lithium solution from seawater or brine, which uses lithium manganate adsorbent to absorb and extract lithium, and the obtained eluent is subjected to two-stage Conventional electrodialysis concentration can obtain Li + Concentrated solution with a content of about 1.5%, after the first-stage electrodialysis desalination water is deeply desalted by another stage of electrodialysis, a desalted solution with a lithium content of 10ppm to 100ppm is obtained, which is returned to the adsorption lithium extraction step and used as adsorption raw water; but the The method cannot directly deal with lithium carbonate washing water or a slightly alkaline solution with a similar composition, when the Ca in the raw water 2+ , Mg 2+ , SO 4 2- When the plasma content increases, it is easy to form precipitates on the membrane surface of the concentration chamber; the TDS (total dissolved solids) value in the obtained desalination solution is still high, and cannot be used as fresh water or deionized water; The method for separating magnesium and concentrating lithium from salt lake brine uses monovalent ion-selective ion-exchange membrane electrodialysis, and realizes the separation of magnesium and lithium and Li at the same time. + Concentration, Li in the concentrate + The content can be increased to 10g / L or higher, but this technology only limits the stock solution to the ratio of magnesium to lithium (that is, the Mg in the stock solution 2+ with Li + The mass ratio of salt lake brine and its evaporated concentrated brine are 1 to 300

[0007] The above technologies are only for Li in lithium-containing liquid + recovery, but not for lithium carbonate washing water and pyrolysis mother liquor that contain more CO 3 2- and HCO 3 - , or a slightly alkaline lithium-containing waste liquid with a similar composition for recycling, which cannot achieve Li + Simultaneous recovery with fresh water (or deionized water)

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