Deep Purification of Lithium Compounds to Remove Chemical and Radioactive Impurities

Possibility of performing deep purification of lithium hydroxide solutions to remove admixtures of alkaline-earth and transition metals, magnesium, aluminum, uranium, thorium, and radium radionuclides (strontium) by using the sorption and membrane methods has been examined. It was shown that successive procedures of mechanical filtration, ultrafiltration with a ceramic membrane having pore size of 50 nm, and sorption purification on an imine carboxyl cation exchanger make it possible to obtain lithium carbonate with no less than 99.9% main substance. The content of impurities being determined in the sample obtained does not exceed 0.005-0.01 wt %. The specific activity of a sample as regards the sum of alpha- and beta-emitters does not exceed their lower detection limit (less than 0.1 Bq/g).