PROCESS OF PRODUCING H-PURITY LITHIUM CARBONATE FROM LITHIUM-BEARING CHLORIDE BRINES Russian patent published in 2006 - IPC C01D15/08 

FIELD: industrial organic synthesis.

SUBSTANCE: process comprises: preparation of chloride lithium concentrate, purification of chloride lithium concentrate to remove major part of calcium, magnesium, and sulfate ion impurities, and reagent-mediated precipitation of lithium carbonate from purified chloride lithium concentrate. Precipitation of lithium carbonate is performed by means of water slurry of ammonium bicarbonate at 20-40°C. Carbon dioxide thereby formed is withdrawn from reaction space and, after removing ammonia impurity therefrom, is used as carbonation agent to convert precipitated and separated from liquid phase lithium carbonate into saturated lithium bicarbonate solution. From the latter, pure impurities-free lithium carbonate is precipitated on heating. Mother liquor obtained from lithium carbonate precipitation operation is evaporated to give solid phase of ammonium chloride and liquid phase containing 300-350 g/L lithium chloride. Liquid phase is separated from solids and returned to lithium carbonate precipitation operation and solid phase of ammonium chloride is washed out with saturated ammonium chloride solution to remove remains of lithium chloride and then dried.

EFFECT: avoided use of sodium ions in lithium carbonate precipitation process, utilized recycled carbon dioxide, and eliminated waste solutions.

2 cl, 4 dwg, 1 tbl, 2 ex