Lithium carbonate production process and apparatus
A method of forming lithium carbonate from a lithium-bearing solution including: evaporating the lithium-bearing solution to precipitate a first group of impurities; removing the first group of impurities to form a first purified solution; and performing a flash crystallisation step within a predetermined temperature range to crystallise a second group of impurities from the first purified solution; removing the second group of impurities from the first solution to form a second purified solution, wherein at least 90 wt % of lithium is recovered from the first purified solution; and reacting the second purified solution with a metal carbonate to form lithium carbonate of at least 90 wt % purity.
1 . A method of forming lithium carbonate from a lithium bearing solution including:
removing a first group of impurities comprising calcium and sodium-containing salts from the lithium-bearing solution to form a first purified solution;
performing a crystallisation step by flash crystallization within a temperature range from 13° C. to 20° C. to crystallise a second group of impurities comprising sodium, potassium and boron-containing impurities from the first purified solution;
removing the second group of impurities from the first purified solution to form a second purified solution, wherein at least 95 wt % of lithium is recovered from the first purified solution;
reacting the second purified solution with a metal carbonate to form lithium carbonate of at least 95 wt % purity.
2 . The method of claim 1 , including a filtering step to remove the first group of impurities.
3 . The method of claim 1 , wherein the evaporating step forms a first purified solution having a lithium concentration of at least 3,000 ppm.
4 . The method of claim 1 , wherein the crystallisation step recovers at least 98 wt % of the lithium from the first purified solution.
5 . The method of claim 1 , wherein the crystallizing step is performed at a temperature from 13° C. to 17° C.
6 . The method of claim 1 , including a filtering step to remove the second group of impurities formed during the crystallisation step.
7 . The method of claim 1 , including a second crystallisation step to separate sodium and potassium-containing impurities from the first purified solution.
8 . The method of claim 1 , wherein the crystallizing step forms a second purified solution having a lithium concentration of at least 10,000 ppm.
9 . The method of claim 1 , wherein the reacting step involves reacting the second purified solution with sodium carbonate to form lithium carbonate.
10 . The method of claim 1 , wherein the reacting step forms lithium carbonate of at least 99 wt % purity.
11 . The method of claim 1 , including a step of removing calcium carbonate from the second purified solution before the reacting step.
12 . The method of claim 1 , including a recycling step which directs liquor from the reacting step to the crystallisation step.
13 . The method of claim 1 , including a step of refining the lithium carbonate to a purity of at least 95 wt %.