Method for preparing solid lithium salt from lithium solution

A method for preparing a solid lithium carbonate from a waste solution of a waste lithium battery, comprising the steps of,

• preparing a mixture in which phosphoric acid is added to a waste solution of a waste lithium battery containing lithium, in step i;
• adding a basic solution to the prepared mixture to adjust the pH to 10 to 12, in step ii;
• making the pH-adjusted mixture react by raising its temperature of 70° C. to 90° C. and recovering lithium phosphate by filtration, in step iii;
• preparing a lithium sulfate solution in which distilled water and sulfuric acid are added to the recovered lithium phosphate, in step iv;
• recovering a solid lithium sulfate by evaporative concentration of the lithium sulfate solution, in step v;
• adjusting the pH by adding distilled water and a basic solution to the recovered solid lithium sulfite to obtain a pH-adjusted solution, in step vi;
• and
• preparing a solid lithium carbonate by adding a carbonate to the pH-adjusted solution, in step vii.