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.