Method for extracting lithium carbonate from carbonate brine

Abstract

The invention discloses a method for extracting lithium carbonate from carbonate brine. A salt-gradient thermal-insulation solar pond is made of clay, a black ethylene-propylene-diene monomer (EPDM) waterproof roll, a geomembrane or high-density polyethylene plastic spraying canvas and the like are paved on the surface of the bottom of the pond to serve as liners, and a heat exchange pipeline is paved at the position 0.5-1m higher than the pond bottom. Lithium-rich brine prepared by freezing and solarization is directly injected into the salt-gradient thermal-insulation solar pond, a layer of fresh water is paved on the surface layer of the brine, the brine is warmed under the dual functions of solar radiation and geothermal water-heat exchange, lithium carbonate is separated out in a concentrated mode, and finally lithium-mixed salt obtained in the salt-gradient thermal-insulation solar pond is scrubbed through appropriate-temperature fresh water. The methods of the salt-gradient thermal-insulation solar pond, the geothermal water-heat exchange, scrubbing of the appropriate-temperature fresh water and the like are combined and applied to extraction of lithium carbonate from carbonate brine, the production efficiency and product quality are greatly improved, the production cycle is shortened, the production cost is reduced, and lithium carbonate ore concentrate can be obtained directly locally.

Description

Technical field [0001] The invention relates to a method for extracting inorganic salts, and more precisely, to a method for extracting lithium carbonate from carbonate brine. Background technique [0002] With the continuous development and application of high-performance lithium materials, the world's demand for lithium is increasing. In recent years, the extraction of lithium from salt lake brines has gradually replaced the extraction of lithium from hard rock lithium ore and has become the main production method of lithium salts. Lithium resources in my country are relatively abundant, and they are mainly distributed in salt lakes in plateau areas. Among them, the lithium resources in salt lake brines in Tibet are mainly carbonate type. The research on the extraction and utilization of lithium from brine is a very meaningful work. [0003] Chinese patent 99105828.3 (Method for extracting lithium salt from carbonate-type brine) discloses a method for extracting lithium salt fro...

AI Technical Summary

Problems solved by technology

[0008] Although lithium carbonate can be concentrated and precipitated by artificial heating or carbonization, it needs to consume a lot of fossil fuels, which is not feasible in the energy-poor Tibetan plateau area.

However, purely relying on solar radiation to heat the brine to form solar ponds to crystallize and precipitate lithium, although the brine can be heated up without evaporation, the temperature rise rate of the brine is relatively slow, resulting in a long production cycle. more than two months

Moreover, the current thermal insulation measures for the pool body are not only costly, but also unable to meet the process requirements, especially the poor heat storage capacity of the pool body, which makes the temperature difference between day and night of the brine large, and under the strong sunlight during the day, the brine The highest temperature can rise to 40°C, but the temperature of the brine will drop significantly at night, resulting in the crystallization of halite, borax and other salts from the low-temperature brine, and part of the lithium carbonate that has precipitated from the high-temperature brine will return again. Dissolving into brine seriously affects the grade of lithium carbonate

In addition, the lithium mixed salt produced by the above-mentioned patented methods (99105828.3, 02129355.4, 200620172864.2) needs to be transported to the mainland for long distances for processing and purification due to its low grade, which will consume a lot of shipping costs and energy every year.

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