Comprehensive extraction of valuable metals from lepidolite by mechanical activation and low temperature sulfation roasting

Abstract

Lepidolite is a valuable mineral resource of lithium, rubidium and cesium. In this paper, A systematic investigation has been conducted on the integrated process of mechanical activation, sulfation roasting, and water leaching for the extraction of valuable metals from lepidolite concentrate. After mechanical activation, the lepidolite concentrate is mixed with sulfuric acid and roasted at low temperature, and then leached with water. The optimum process conditions were determined as follows: sulfuric acid concentration 80 %, acid-to-ore ratio 1:1, roasting temperature 300 °C, roasting time 5 h, water leaching temperature 80 °C, liquid-to-solid ratio 3:1, and water leaching time 2.5 h. Under the optimal conditions, the extraction rates of Li, Rb, Cs, Al and K reached 92.16 %, 89.96 %, 93.44 %, 94.52 %, and 91.22 %, respectively. During the process of sulfation roasting, the alkali metal elements in the lepidolite were transformed into water soluble sulfate. After water leaching, only stable SiO₂ remains in the slag phase, which is beneficial to the subsequent treatment and utilization of the slag phase. The kinetic studies revealed that the leaching process is dominated by the unreacted shrinking core model with a mixed control mechanism. This work presents a viable approach for the comprehensive recovery of valuable metals from lepidolite concentrate.