PREPARATION METHOD OF ULTRA-PURE LITHIUM COMPOUND AND SYSTEM USING THE SAME

摘要

PURPOSE: A method for preparing lithium compounds of high purity and a system using the method are provided to cost effectively prepare lithium compounds of high purity based on low energy by obtaining a lithium phosphate aqueous solution by dissolving lithium carbonate of low purity into a phosphoric acid, and electrolyzing the lithium phosphate aqueous solution. CONSTITUTION: A method for preparing lithium compounds of high purity includes the steps of: obtaining a lithium phosphate aqueous solution by dissolving lithium carbonate of 85% or less purity into a phosphoric acid; and obtaining lithium hydroxide by electrolyzing the lithium phosphate aqueous solution. The purity of the lithium compound is more than or equal to 99.5%. The step of obtaining a lithium phosphate aqueous solution includes the steps of: washing lithium carbonate of 85% or less purity with water; and obtaining a lithium phosphate aqueous solution by dissolving the washed lithium carbonate into a phosphoric acid. The electrolyzing step is performed under the current density of 0.01-0.075A/cm^2 and the electrolysis temperature of 15-25°C. The method further includes a step of forming lithium carbonate by generating a reaction between lithium hydroxide and a carbonation gas or a material containing carbonate. A system for preparing lithium compounds of high purity includes a dissolving unit and an electrolyzing unit.