Extraction of Lithium and Synthesis of Kaolinite from α ‐Spodumene via Alkali Calcination

Abstract Extracting lithium from spodumene by sulfuric acid roasting is the largest commercialized way at present, which not only consumes a large amount of energy but also produces massive waste residue that will cause environmental problems. In this work, a new process for extracting lithium by directly decomposing α ‐spodumene through alkali calcination is designed. The reaction of α ‐spodumene with Na 2 CO 3 at 750 °C for 2 h can decompose it and form nepheline and lithium silicate/sodium silicate. The nepheline and soluble lithium silicate/sodium silicate are separated by water leaching, and 93.9 % of lithium can be leached under optimal conditions. In addition, the synthesis of nano‐kaolinite is investigated with nitric acid solutions. Conversions of 98.7 % were obtained with 0.4 M nitric acid at 250 °C and an L/S ratio of 17.5 L/kg. The water leachate can precipitate Li 2 CO 3 with a purity of 99.0 % by CO 2 after desilicated by CaO. The final yields of Li 2 CO 3 and kaolinite relative to the Li and Si content of the starting minerals are 91.4 % and 48.5 %, respectively. This new method achieves the full utilization of spodumene with lower energy consumption and demonstrates great potential for industrial applications.