Production method of high-purity lithium hydroxide

Abstract

The present invention relates to a production method of high-purity lithium hydroxide. A crystallization mother liquor waste water is obtained after production of potassium chloride by using a salt lake bittern as the raw material, a magnesium-lithium ratio of the crystallization mother liquor waste water is 200-500:1, an eligible eluant is obtained through ion sieve adsorption and elution of the crystallization mother liquor waste water, and after treatment of the eluant through the ultrafiltration membrane technology, the sectional type nanofiltration technology, the external regeneration continuous hybridization technology and the reverse osmosis technology, a reverse osmosis concentrated solution is obtained. In the reverse osmosis concentrated solution, the content of magnesium ions is <=300 ppm, the content of lithium ions is 4-6 g / L, the content of sodium ions is 3-5 g / L, the content of calcium ions is <=5 ppm, the content of sulfate ions is 1-30 ppm and the content of boron is <=400 ppm. According to the production method provided by the present invention, the reverse osmosis concentrated solution is used as the raw material, the process comprises ultrahigh pressure reverse osmosis continuous hybridization for boron-removing, continuous hybridization for sulfate radical removing, ion-exchange membrane electrolysis, and crystallizing evaporation, and by using the hybridization boron-removing technology, the ion-exchange membrane electrolysis technology and the crystallizing evaporation technology, the high-purity lithium hydroxide is obtained, with the byproducts being the boric acid and sodium hydroxide. The process is continuous, controllable, high in extraction rate, low in production cost and easy to industrialize.

Description

technical field [0001] The invention belongs to the field of salt chemical industry, in particular to a production method of high-purity lithium hydroxide. Background technique [0002] The bittern after extracting potassium is used as raw material. The ratio of magnesium to lithium in the raw material reaches 200-500:1, and the ratio of magnesium to lithium in the qualified eluent after ion sieve adsorption and elution drops to 3-4:1. After ultrafiltration technology, segmented nanofiltration technology, and in vitro regeneration The reverse osmosis concentrate is obtained after separation and purification by continuous separation technology and reverse osmosis technology. Among them, the magnesium ion content is ≤30ppm, the lithium ion content is about 4-6g / L, the sodium ion content is 3-5g / L, the calcium ion content is ≤5ppm, the potassium ion content is ≤300ppm, and the sulfate ion content is 1-30ppm. The content of boron element is ≤400ppm. In the traditional process...

AI Technical Summary

Problems solved by technology

[0009] It can be seen that when extracting lithium from salt lakes, lithium chloride is used to produce lithium carbonate, and then lithium carbonate is used as raw material to produce lithium hydroxide by causticization, the process route is long and complicated, the yield of lithium ions is low, the cost of raw and auxiliary materials is high, and resources are seriously wasted. , poor product quality

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