Lithium sorption by ion exchange

The high demand for lithium is increasing drastically due to its applications in electronic devices, electric vehicles, and other components. The present case study focuses on studying the sorption capacity of two resins − Dowex G26 and Dowex X8 – in capturing lithium from pregnant solutions generated by the leaching of lepidolite and spodumene ores. Preliminary characterization studies were performed using synthetic solutions to understand the behaviour of the resins without the interference of competing ions. The results suggest that Dowex G26 exhibits a higher loading capacity. Additionally, the mass action law and a sigmoid function were used to model respectively the equilibrium in the sorption process and the kinetics of extraction in a continuous fixed bed operation. In a second phase of experiments, the resulting optimal operating conditions were used to study the ion exchange extraction from leaching liquors of lepidolite and spodumene ores. These liquors are complex solutions with competing ions. Ion exchange assays were optimized, and the maximum loading capacity for the leaching liquors was 1.8 meq lithium/g of resin, which corresponds to 71 % of Li sorption. For the elution, the maximum lithium extraction from the resins achieved was 82 %.