Research on the in-situ flocculation behavior of polyferric silicate for enhancing the lithium leachability in lithium-rich clay

The expansion of global lithium demand urgently requires efficient extraction technologies for lithium-rich clay recourse. However, the encapsulation of polysilicate products in the acidic leaching system impedes the migration of lithium from the mineral to the solution, resulting in a low recovery rate of lithium. Here, this study proposes an in-situ flocculation mechanism of Fe3+ on the polysilicate to reconstruct the surface structure, enhancing the leaching efficiency of lithium. Results showed that the flocculation of Fe3+ approaches the Si-O surface and reacts with silicate to form the polyferric silicate (Fe3Si2O5(OH)4). This special configuration eliminates the wrapping and adsorption effect of polysilicate while promotes the diffusion of Li+. Increased FeCl3 concentration and higher leaching temperature are beneficial for the leaching efficiency of Li. Under optimized conditions, the Li leaching efficiency in the FeCl3 leaching system reaches up to 92.81 %. This work introduces Fe3+ to overcome the limiting effect of polysilicate during acidic leaching, and affords extraordinary recovery of lithium from clay resources.