Precipitation of lithium phosphate from lithium solution by using sodium phosphate

Abstract Lithium was studied to precipitate into Li 3 PO 4 by adding Na 3 PO 4 under various experimental conditions such as initial lithium concentration of the solution, initial pH of the solution, temperature, and the mol equivalent ratio of Na 3 PO 4 . The precipitation mechanism of Li 3 PO 4 was investigated with the change of pH value of the solution over time. The precipitation efficiency of Li 3 PO 4 was 95.4% in the condition of the mol equivalent ratio of Na 3 PO 4 of 1, initial Li concentration of 7 g/L, initial pH of 9.5, and at 90°C. When Na 3 PO 4 was added three times, divided in the mol equivalent ratio of 1 via the hydrolysis reaction of PO 4 3− , which inhibits the Li 3 PO 4 precipitation reaction, an excellent precipitation efficiency of 98.4% was obtained. Co‐precipitated Na 2 HPO 4 with Li 3 PO 4 was washed by distilled water in the condition of solid/liquid ratio of 10% and at 90°C. The purity of the final Li 3 PO 4 product was found to be 99.1%.