Extraction of aluminium by autoclave hydrochloric acid leaching of boehmite-kaolinite bauxite

Abstract

In this paper we investigate the process of autoclave extraction of boehmite-kaolinite bauxite for Severoonczhsk deposits by hydrochloric acid. The effect of temperature and duration of the process on transition of aluminum into solution has been studied. The apparent activation energy was defined for the process. The influence of hydrochloric acid concentration on alumina transition in solution was shown. Determined the apparent degree of the process on reagents. The obtained results allow to allocate 3 limiting stages of the process: 150 - 160°C - A chemical reaction (Ea = 70.88 kJ/mol), 160 - 170°C - Intermediate region (Ea = 40.22 kJ/mol), 170 - 180°C - Diffusion area (Ea = 22.66 kJ/mol). Thermodynamic modeling of physicochemical processes underlying the preparation of aluminum containing solutions has been performed. It has been demonstrated that the major aluminum species in solution are aluminum chlorides and hydroxychlorides.