Leaching efficiency of sulfuric acid on selective lithium leachability from bauxitic claystone

Abstract The explosive demand for lithium calls for new lithium resources. A lithium-rich bauxitic clay was selected, and its material composition, phase transformation, lithium leaching efficiency using sulfuric acid were investigated after calcination treatment. In this study, XRF, ICP-AES, ICP-MS, XRD and SEM were employed to characterize bauxitic clay and its calcining products and leaching residues. The results show that bauxitic clay mainly consists of diaspore, illite, montmorillonite and anatase with a major chemical composition of Al2O3 (48.01%), SiO2 (33.06%), K2O (3.88%), TiO2 (2.25%), Fe2O3 (1.07%), MgO (0.46%), and lithium 3170 μg/g. The optimum calcination temperatures were 500 and 600 °C, with 72.34% and 73.61% lithium extracted, respectively, using 15% sulfuric acid leaching for 1 h. The optimal leaching conditions for lithium extraction were a leaching reaction time of 60 min and a 20% (wt/v) sulfuric acid concentration. Lithium leaching in this study was considered to occur via ion exchange instead of mineral dissolution. The findings of this study would be useful and interesting for lithium recovery from bauxitic clay.