Lithium extraction methods from spodumene include beneficiation to produce a concentrate, which requires structural conversion. This process mainly includes the sulfuric acid method, the sulfate roasting method, the alkali method, and the chlorination roasting method. Although sulfuric acid-based processes are industrially mature, producing one ton of lithium carbonate by this method generates 8 – 10 tons of solid waste residue. Based on the chemical assay, the solid waste residue still contains 0.3% of Li. This study will investigate a green process for lithium recovery from waste spodumene processing using citric acid. This study investigates the effect of various leaching variables, including temperature, time, acid concentration, and solid-to-liquid ratio, on lithium extraction efficiency. Raw material characterisation has been conducted using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM) on representative powdered bulk samples. The leach solution has been analysed via ICP-OES to determine elemental composition and calculate recovery rates. After 24 hours of leaching using 1 M citric acid, 10% solid-liquid ratio, and a 60 °C leaching temperature, lithium recovery is at the highest level, at up to 65.7%. Moreover, the kinetics of lithium leaching were studied to determine the controlling mechanism using the shrinking core model. The obtained value of Ea was 52.77 kJ/mol.
Azmi et al. (Mon,) studied this question.