Patent ID: 8057764

Claim:
Lithium carbonate prepared by a continuous process for directly preparing high purity lithium carbonate from lithium containing brines comprising: preparing a brine containing about 6.0 wt % lithium and further containing other ions naturally occurring in brines; adding mother liquor containing carbonate from a prior precipitation step to precipitate magnesium as magnesium carbonate; adding a solution of CaO and sodium carbonate to remove calcium and residual magnesium; precipitating lithium carbonate from the purified brine by adding soda ash solution; filtering the resultant solution to obtain solid lithium carbonate; preparing an aqueous slurry of the lithium carbonate in a reactor equipped with an inlet for introducing carbon dioxide gas and introducing carbon dioxide gas through the inlet into said aqueous slurry to form an aqueous lithium bicarbonate solution, the reactor being at a temperature from at least minus 10 to 40Â° C.; passing said aqueous lithium bicarbonate solution through a filter to clarify the solution and optionally an ion exchange column for further calcium and magnesium removal; introducing said filtered lithium bicarbonate solution into a second reactor and adjusting the temperature of the solution to from 60 to 100Â° C. to precipitate ultra-pure lithium carbonate with sodium less than 0.0002 wt %, calcium less than 0.00007 wt % and magnesium less than 0.00001 wt %.