An environment-friendly strategy for comprehensive recovery of Li, Al and Si from low-grade clay-type lithium ore

Due to the development of new energy vehicle industry, global lithium consumption increases rapidly. Extracting lithium from abundant clay-type lithium ore is an effective strategy to secure a cost-effective lithium supply chain. However, lithium extraction from clay-type lithium ore currently faces with the problems of high solid residue yield and low extraction selectivity for lithium. In addition, the compounds of silicon and alumina in ore processing high economic value are usually ignored. Here, we developed a sustainable process for the comprehensive recovery of Li, Si and Al from clay-type lithium ore by combining NaOH-assisted roasting with sulfuric acid leaching. Firstly, the leaching behavior of lithium under different roasting conditions and acid leaching conditions was systematically investigated. Under the optimal acid leaching condition, the lithium leaching rate reached 96.8%, while the solid residue yield was only 8% based on the raw ore. Taking advantage of the gelling property of Si/Al-containing leaching solution, a lithium-containing solid was obtained by drying and roasting of the gel product. The selective extraction of lithium was easily achieved by washing the solid with water, and the high-value utilization of solid residues in the whole process to prepare nanowires mullite, alumina and corundum was realized. The mechanisms of multi-element recovery elucidated that the formation of nepheline phase during NaOH-assisted roasting promotes the efficient leaching of lithium and reduces the solid residue by acid leaching. After roasting of gel product, Si and Al combined to form mullite, while lithium remained in a free state, allowing further selective lithium elution by water and simultaneous recovery of Si and Al. This work provides fresh perspectives on the sustainable and comprehensive utilization of clay-type lithium ore.