The Leaching Of Bauxite Ores With Sulfuric Acid For Activated Alumina Preparation

Activated alumina is widely used as catalyst supports in the fertilizer and petrochemical industry due to its good thermal stability, high specific surface area and controllable porosity. Traditional alumina production process is complex and high-cost. A simple and low-cost preparation process of alumina by direct neutralization with acid and alkaline leaching liquids of bauxite was proposed by our group. The leaching process of bauxite with alkaline and the parameters for aluminum sulfate method have been studied by X. Y. Huang. This paper systematically deals with the leaching process of bauxie with sulfuric acid, the kinetics and thermodynamics of this leaching process as well as the iron-removing prcosess. Activated alumina with appropriate property as a catalyst support was obtained based on our research. The results are as follows:(1) No7#bauxite from Australia was found to suitable for acid leaching based on the investigation on element and crystallinity analysis of bauxite ores from different regions as well as their leaching performance. The optimum conditions both for the leaching technology of bauxite ores with sulfuric acid and for iron-removing were established.(2) Kinetics study on leaching of bauxite with sulfuric acid revealed that shrinking core model was suitable to describe the leaching process with the temperature of40-100℃. The leaching of boehmite was controlled by internal diffusion, with activation energy of9.48kJ/mol. The leaching of hematite was controlled by chemical reaction over the temperature range40-90℃with activation energy of28.02kJ/mol, and by internal diffusion over the temperature range90-110℃with activation energy of9.81kJ/mol respectively.(3) Activated alumina as a catalyst support was prepared using the new process, with pore volume of l.Oml/g and specific surface area of289m2/g.