Method for extracting lithium carbonate from carbonate brine

Abstract

The invention discloses a method for extracting lithium carbonate from carbonate brine. A salt gradient heat-preserving solar pond is built by clay; black ethylene-propylene-diene monomer waterproof coiled material, geomembrane or high density polyethylene spraying canvas and the like are laid at the bottom surface of the pond as the mat; a heat exchanging pipeline or an electric heating device is arranged 0.5-1m above the bottom of the pond; lithium-rich brine which is prepared by freezing and solarization is directly poured into the salt gradient heat-preserving solar pond, a layer of fresh water is laid at the surface of the brine, the brine is heated by the double action of solar irradiation and heat exchanging or electric heating and lithium carbonate is separated out concentratedly; and finally, lithium mixed salt obtained in the salt gradient heat-preserving solar pond is scrubbed with fresh water at proper temperature. The combination of the salt gradient heat-preserving solar pond, the heat exchanging or electric heating device and scrubbing by fresh water at proper temperature is applied to the extraction of lithium carbonate from carbonate brine, therefore, the production efficiency and the product quality are greatly improved, the production cycle is shortened, the production cost is lowered and lithium carbonate concentrate is obtained directly.

Description

technical field [0001] The invention relates to a method for extracting inorganic salts, more precisely, relates to a method for extracting lithium carbonate from carbonate type 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, lithium extraction from salt lake brine has gradually replaced lithium extraction from hard rock lithium mines and has become the main production method for lithium salts. Lithium resources in my country are relatively abundant, and they are mainly distributed in salt lakes in plateau areas. Among them, lithium resources in salt lake brines in Tibet are mainly carbonate-type, which is a very meaningful work for the extraction and utilization of lithium from brines. [0003] Chinese patent 99105828.3 (method for extracting lithium salt from carbonate-type brine) discloses a method for extracting lithium salt from car...

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 freight and energy every year

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