A method for the production of lithium hydroxide high purity from a lithium - and other alkali - - and alkaline earth metal halides, lye containing

摘要

A process is described in which a brine from natural or other sources, containing lithium and other alkali and alkaline earth metals primarily as the halides, is preliminarily concentrated to a lithium content of about 2 to 7% to separate most of the alkali and alkaline earth metals other than lithium by precipitation, the pH of such a concentrated brine is then increased to about 10.5 to about 11.5, preferaly utilizing a product of the process, lithium hydroxide to precipitate substantially all of any remaining magnesium contaminants, and adding lithium carbonate to remove the calcium contaminants to provide a purified brine which is electrolyzed as the anolyte in a cell having a cation selective permeable membrane separating the anolyte from the catholyte, the latter being of water or aqueous lithium hydroxide, whereby the lithium ions migrate through the membrane to form substantially pure aqueous lithium hydroxide in the catholyte, a product from which highly pure lithium crystalline compounds such as lithium hydroxide monohydrate or lithium carbonate may be separated.