Justin Paris, Shiva Mohammadi-Jam, Ronghao Li, Jingyi Liang, Hak Jun Oh, Ozan Kökkılıç, Sidney Omelon, Kristian E. Waters*
Department of Mining and Materials Engineering, McGill University, 3610 Rue University, Montreal H3A 0C5, Canada
Demand for lithium has risen significantly with the prevalence of lithium-ion batteries in renewable energy technology. Spodumene is the primary lithium-bearing mineral of interest, due to its comparatively high grade and simple composition. However, methods for lithium extraction from spodumene remain complex. In this study, phosphoric acid was investigated as an alternative leaching agent. Preliminary leach experiments were performed on 1 g samples of pure β-spodumene with varying acid concentration, temperature, residence time and liquid to solid ratio. Chemical analysis of the leach filtrates and residues by inductively coupled plasma optical emission spectroscopy (ICP-OES) revealed that a > 40 % lithium leaching efficiency was achieved at an acid concentration of 8 M, a temperature of 100 °C, a residence time of 8 h, and a liquid to solid ratio of 10 mg/L. With further optimization, the leaching method could prove promising for lithium extraction from spodumene as well as other lithiumbearing silicates, such as lepidolite, zinnwaldite, and petalite.
Keywords: lithium extraction, spodumene, acid leaching, phosphoric acid, leaching mechanism