Patent ID: 6921522

Claim:
A continuous process for directly preparing lithium chloride from lithium containing brines comprising: preparing a brine containing about 6.0 wt % lithium and further containing other ions such as sodium, magnesium, calcium, and sulfates naturally occurring in brines; adding a solution of CaO and sodium carbonate to remove calcium and magnesium as precipitates; filtering to remove the calcium and magnesium precipitates to yield a purified 6% lithium brine; cooling the purified 6 wt % lithium brine to a temperature of from minus 30 to +10° C. to reduce the sodium content to not more than 0.05 wt % Na; adjusting the pH of the reduced sodium solution to acidic, preferably to pH 4 with hydrochloric acid; adding a barium solution to remove any sulfate as barium sulfate; adding lithium hydroxide to the barium treated solution to raise the pH to less than 10, preferably 6-7; adding an aqueous oxalate mixture comprising lithium oxalate and calcium oxalate to further precipitate calcium as calcium oxalate; adjusting the pH to slightly above pH 10; filtering to remove calcium oxalate; passing the solution through an ion exchange column to remove any divalent and trivalent cations; adjusting the pH to from 6 to 8, preferably 7; and charging the purified brine into a crystallizer to produce anhydrous low calcium, low magnesium lithium chloride crystals.