Thermal and Mechanical Activation in Acid Leaching Processes of Non-bauxite Ores Available for Alumina Production—A Review

The rapid development of the global alumina and aluminum industry is directly linked to the increasing demand for these materials. Given the limitations of bauxite ores as the primary resource for alumina production, there is a pressing need to explore alternative sources, particularly in regions lacking adequate bauxite reserves. This review aims to provide insights into the recovery of alumina from non-bauxite sources such as aluminosilicate clay minerals and coal fly ash. The focus is on acid leaching processes, which have been established as the most efficient methods for alumina extraction, significantly enhanced by thermal and mechanical activation. A comprehensive examination of hydrochloric, sulfuric, and nitric acid leaching processes is presented, highlighting their effectiveness in improving alumina yield from thermally or mechanically activated materials. The findings underline the potential of these alternative resources and processes in sustaining alumina production in an evolving industrial landscape.