Direct lithium extraction using Australian spodumene refinery residue: a waste to value approach

• An Australian spodumene refinery residue was repurposed for direct lithium extraction. • A comprehensive investigation on its physicochemical characteristics was conducted. • The material exhibited a promising performance for lithium extraction from simulated brine solution. • In-depth mechanistic studies were carried out to reveal the adsorption kinetics and underlying the lithium uptake mechanism. Lithium extraction from hard rocks generates a substantial amount of solid waste, i.e., leached spodumene residue. This work contributes to developing a characteristic understanding of this waste residue and evaluating its potential application in direct lithium extraction. Firstly, the residue was comprehensively analysed through advanced characterisation techniques. Subsequently, the material was applied for direct lithium extraction from simulated brine, achieving an optimal adsorption capacity of 14.25 mg·g -1 at 90 °C and pH 12.43. Mechanistic and kinetic studies revealed an ion-exchange process (H + /Li + ), facilitated by the porous channels inside the structure. Further investigations into competing cations and reusability revealed a selectivity order of Li⁺ > Na⁺ > K⁺ > Mg 2+ , with respective separation factors of 10.94, 12.40, and 16.84, underscoring the material’s strong potential for practical brine processing. This waste-to-value approach not only minimises the environmental concerns but also enhances resource utilisation across the overall lithium economy.