Extraction of valuable metals from lepidolite

Salt roasting with Na2SO4 + CaCl2 followed by water leaching was used to extract alkali metals from lepidolite. The experiments indicated that the best mass ratio of lepidolite /Na2SO4/CaCl2 during roasting was 1:0.5:0.3. The extraction of Li, Rb and Cs were all > 90% after 0.5 h at 880 °C. The recovery of Li was essentially constant when roasted at 830–930 °C. The flexible roasting condition is easily controlled in industrial application. After leaching in water, the solution was cooled to − 5 °C for 2 h to crystallise 92.1% of the sulphate and 3.9% of the chloride as Na2SO4·10H2O and NaCl, respectively. Evaporation and precipitation using Na2CO3 produced Li2CO3 crystals with > 99.5% purity and a solution from which Rb and Cs could be recovered.