Effects of mechanical activation on lithium extraction from a lepidolite ore concentrate

Mechanical activation in order to improve lithium recovery from a lepidolite ore concentrate was investigated. The concentrate was mechanically activated using different milling times and the effect on the resulting products was evaluated by X-ray powder diffraction, FTIR spectroscopy, TG-DTG analysis, SEM and particle size analysis by laser diffraction. The mechanical activation leads to lepidolite amorphization and concomitant improvement of the reactivity by sulfuric acid digestion and water leaching. About 85% of Li recovery was achieved when the concentrate was activated for 15 min and afterwards digested at 165 °C, during 4 h, using an acid/concentrate ratio of 650 g/kg. Li recoveries above 70% were reached even using digestion temperatures lower than 100 °C. However, to increase recovery, temperatures over 140 °C are more suitable. Results obtained showed that is possible to apply a low temperature technology for recovering Li from hard rock minerals, using mechanical activation.