A continuous process for directly preparing high purity lithium carbonate from lithium containing brines by preparing a brine containing about 6.0 wt % lithium and further containing other ions naturally occurring in brines; adding mother liquor containing carbonate to precipitate magnesium; adding a solution of CaO and sodium carbonate to remove calcium and any residual magnesium; precipitating lithium carbonate from the purified brine by adding soda ash solution; filtering to obtain solid lithium carbonate; preparing an aqueous slurry of the lithium carbonate and introducing carbon dioxide gas at a temperature from at least minus 10 to +40.degree. C.; passing the lithium bicarbonate solution through a filter to clarify the solution; introducing said filtered lithium bicarbonate solution into a reactor and adjusting the temperature of the solution to from 60 100.degree. C. to precipitate ultra-pure lithium carbonate.