METHOD OF MAKING HIGH PURITY LITHIUM HYDROXIDE AND HYDROCHLORIC ACID.

摘要

The present invention relates to a process for producing high purity lithium hydroxide monohydrate, comprising following steps: concentrating a lithium containing brine; purifying the brine to remove or to reduce the concentrations of ions other than lithium; adjusting the pH of the brine to about 10.5 to 11 to further remove cations other than lithium, if necessary; neutralizing the brine with acid; purifying the brine to reduce the total concentration of calcium and magnesium to less than 150 ppb via ion exchange; electrolyzing the brine to generate a lithium hydroxide solution containing less than 150 ppb total calcium and magnesium, with chlorine and hydrogen gas as byproducts; producing hydrochloric acid via combustion of the chlorine gas with excess hydrogen and subsequent scrubbing of the resultant gas stream with purified water, if elected to do so; and concentrating and crystallizing the lithium hydroxide solution to produce lithium hydroxide monohydrate crystals.