Patent ID: 8691169

Claim:
A method for producing battery grade lithium carbonate starting with brine solutions from natural or industrial sources comprising the following steps: addition of calcium hydroxide to brine in order to precipitate magnesium, calcium and boron; concentrating the treated brine by solar evaporation in order to precipitate and separate magnesium hydroxide, pentahydrated calcium sulfate and heptahydrated calcium borate generating a magnesium depleted brine; treating said magnesium depleted brine with an organic solvent in order to remove residual boron and yielding a boron depleted brine; adding sodium carbonate to said boron depleted brine in order to precipitate the lithium carbonate; collecting said lithium carbonate to form a lithium carbonate cake; reacting said lithium carbonate cake with carbonic acid produced by reacting carbon dioxide gas with water in order to form bicarbonate of lithium; separating the bicarbonate of lithium in solution from insoluble impurities contained in said lithium carbonate; heating said bicarbonate of lithium solution in order to convert into a lithium carbonate precipitate; separating said lithium carbonate precipitate from said bicarbonate of lithium solution; and drying said lithium carbonate precipitate.