Preliminary investigation into lithium extraction by phosphoric acid leaching of spodumene

Lithium demand has risen significantly with the dominance of lithium-ion batteries in renewable energy technology. Spodumene is a primary lithium-bearing mineral of lithium extraction interest, due to its comparatively high grade and simple composition. However, lithium extraction processes from spodumene remain complex. In this study, phosphoric acid was investigated as a lithium leaching agent. Preliminary leach experiments were performed on 1 g of pure β-spodumene, with varying phosphoric acid concentration, temperature, residence time, and liquid-to-solid ratio. Chemical composition of the leach filtrates and residues by inductively coupled plasma optical emission spectroscopy (ICP-OES) revealed that > 40 % lithium leaching efficiency was achieved at an 8 M acid concentration, 100 °C, an 8 h residence time, and a liquid-to-solid ratio of 10 mL/g. With further optimization and understanding of the leaching mechanism, phosphoric acid could prove to be a suitable alternative for selective lithium extraction from spodumene.