Interactions in the metakaolinite-sulfuric acid system

An experimental study and thermodynamic analysis were performed on a multicomponent, heterogeneous system of metakaolinite with sulfuric acid at 25-100degreesC. The equilibrium compositions of liquid, solid, and gaseous phases were calculated. Solubility isotherms and species distribution diagrams for aluminum and silicon are compared. Conditions for the most complete recovery of aluminum and the minimum solubilization of silicon were determined; the formation of mixed aluminum and silicon compounds and aluminum loss with solid phases were practically eliminated as a result. The optimal leaching parameters are pH 2.0-2.7 and 100degreesC.