A novel method for extraction of alumina from red mud by divalent alkaline earth metal oxide and soda ash sinter process followed by thermo chemical leaching in suitable caustic concentration at 105ºC for different times is presented in this paper. During sintering sodalite/cancrinite, gibbsite and boehmite in red mud is converted to sodium aluminate as well as stable phases of divalent alkaline earth metal ferrite, titanate and silicate. In the above novel economic process and extraction of alumina from red mud of 97.64%, 98.70% and 99.50% was achieved using CaO, MgO and BaO respectively. The morphological behaviours of sinter products and leached products were studied by using scanning electron microscope (SEM) and X-ray diffractometer (XRD).
Keywords: red mud, sintering, leaching and divalent alkaline earth metal oxide