An effective method for directly extracting lithium from α-spodumene by activated roasting and sulfuric acid leaching

Abstract

The global trend toward electrification has encouraged lithium's market position to grow prominently. Spodumene is the focus of lithium extraction owing to its abundant lithium resources. In this study, a novel lithium extraction method was proposed for α-spodumene by combining activated roasting and sulfuric acid leaching. First, the thermodynamics of the roasting process demonstrated that α-spodumene was converted into β-spodumene, which reacted with CaO to produce acid-soluble LiAlSiO4 and CaSiO3 concurrently. The addition of CaO reduced the melting temperature, which promoted the structural transformation of β-spodumene and further acid leaching. Then, the influences of various factors on lithium extraction were investigated by a single-factor test. A lithium leaching yield of 96.18% was obtained under optimum conditions: 20% CaO, roasting temperature of 1200 °C, holding time of 1.5 h, H2SO4 concentration of 120 g/L, liquid–solid ratio of 7:1 mL/g, leaching temperature of 80 °C and leaching time of 1.5 h. Finally, Li entered into leach liquor by the action of sulfuric acid, and the main components of the leach residue were silicate and calcium sulfate. Compared to the conventional acid approach, this method has a higher lithium recovery and lower energy and acid consumption (decrease by approximately 0.42 kg/ kg).