Treatments of a Nigerian spodumene ore: activation, extraction, and kinetics studies

The high electro-active behaviour of lithium metal has positively influenced its usage as an energy material, forcing efforts on lithium liberation from ore deposits to surge. An alumino-silicate lithium ore (spodumene-LiAlSi2O6) suffers from the challenges of high processing temperature, high acid consumption, and a complex purification process during treatments. This study adopted the combination of activation processes followed by direct acidic leaching as the basic steps of lithium extraction and impurity removal to kerb some of the encountered challenges. Initially, through activation techniques involving mechanical grinding and the froth flotation process, the sample revealed high spodumene beneficiation from the initial (48.5 wt% to 91 wt%) through XRD characterisation with the presence of less crystalline β-phase (00-033-0786). The direct acid step for lithium extraction and impurity reduction was found to be optimal at 85°C leaching temperature, 120 min leaching time, and 3.0 mol/L sulphuric acid concentration. The kinetic modelling of the shrinking-core model revealed that the leaching process followed a product-layer diffusion-controlled model, with an activation energy of 23.3 kJ/mol. Finally, a highly beneficiated spodumene-rich crystalline phase consistent with LiAlSi₂O₆ (JCPDS 04-010-3996) was obtained, indicating the effective removal of associated gangue minerals during the activation and leaching processes.