PREPARATION OF LITHIUM HYDROXIDE

The invention relates to a method of using an aqueous solution discharged from an electrochemical apparatus for converting lithium salt dissolved in water to lithium hydroxide and the acid corresponding to the lithium salt, to produce lithium hydroxide monohydrate with simultaneous conversion of this solution to the catholyte required to enter the electrochemical apparatus. The conversion of the aqueous solution into the catholyte is preferably accomplished by a balance discharge of lithium hydroxide monohydrate as a wet product, cooling of the catholyte to remove to balance the amount of heat introduced into the catholyte with the electrochemical process, and balance refreshing of the catholyte with lithium salt in a stirred vessel. In an additional washing step, the balance of the water also reacted during the electrochemical conversion of the lithium salts used is balanced. The lithium hydroxide monohydrate product thus produced is also an object of the invention.