Hydrothermal precipitation and separation of Li as intermediate product Li2SiO3 from the alkali leach liquor

Abstract

With the increasingly essential role of Li in new energy industry, Li extraction from ore has attracted active attention. In the prior study, a process combined thermal activation and alkali leaching was proposed to extract Li from Li concentrate. Previous research found that Li was precipitated as Li2SiO3 and entered into the leach residue at the leaching temperature exceeded 100 °C. Drawing inspiration from this phenomenon, hydrothermal precipitation of Li as intermediate product Li2SiO3 from the alkali leach liquor of Li concentrate was proposed. Firstly, the E–pH diagrams of Li–Si–H2O system were plotted to analyze the feasibility of hydrothermal precipitation Li. And the corresponding operation window was established. Subsequently, the effect of factors including Li/Si ratio, hydrothermal temperature and time, Li and NaOH concentrations on the migration behaviors of Li and Si were explored using the simulated leach liquor. The experimental results were in good consistence with the thermodynamic analysis. Ultimately, the leach liquor was used to precipitate Li at the determined optimal conditions, and the Li precipitation efficiency reached 91.0%. This study provided an innovative strategy for separating Li from the alkali leach liquor of Li concentrate without adding any reagents. An economical and sustainable route for synergistic extraction of Li, Rb, and Cs from Li concentrate was also proposed.