Abstract
This paper presents the extraction process of lithium from lepidolite concentrate by roasting with NaHSO4 followed by water leaching. Results from TG-DSC analysis of feed material and XRD scans of solids justified the thermodynamic modelling of chemical reactions predicted using HSC software package. The roasting of NaHSO4/lepidolite concentrate mixture of mass ratio 2.5/1.0 at 500 °C followed by water leaching at 95 °C yielded 96% of Li extraction. Under these conditions, about 79% Rb and 73% Cs were also leached from calcined lepidolite material. Purification of the lepidolite leach liquor by adjusting the solution pH to 9 using caustic soda resulted in the precipitation of cryolite (NaAlF6) as a primary phase. The purified liquor with pH adjusted to 12 was treated with phosphoric acid to precipitate Li3PO4 to achieve a recovery of about 93%.
