Li Extraction from a-Spodumene Concentrate via Carbonizing Calcination

The conventional lithium extraction method involves the calcination of a-spodumene at 1050 ◦C so that it can be converted to the more-reactive b-spodumene and then a sulfuric acid roasting step at 250 ◦C. Lithium is finally extracted via leaching with water. This method is energy-intensive, leading to high capital and operational costs. In this study, the direct calcination of a-spodumene with the use of sodium carbonate and calcium oxide was examined, aiming to significantly reduce the calcination temperature and completely omit the sulfuric acid roasting step, thereby radically redesigning the lithium extraction process. The calcination product was then leached with different leaching agents, such as water and sulfuric acid, and at different temperatures. The efficiency of the additives was evaluated through the results of lithium extraction achieved during the leaching step. Different leaching agents and temperatures were investigated. The maximum lithium extraction achieved was 96%, obtained after calcination using a sodium carbonate-based method.