Recovery of Titanium Oxide from Undigested Sand of an Indian Alumina Refinery and Preparation of Value Added Titanium Carbide

During the process of alumina production through Bayer’s process, around 60% of unwanted gangue is rejected as ‘undigested sand’ and ‘Red Mud’. This industrial waste material poses environmental and disposal problems. Aluminum oxide constitutes only 38 to 60% of bauxite ore. The rest is made up of Fe2O3, SiO2, TiO2 and some other metallic oxides. After dissolution of alumina in caustic soda, these impurities remain in suspended form which is separated out as undigested sand and subsequently as red mud. Out of these metal oxides, around 8 to 25% of titanium oxide is lost in to this waste. Titanium oxide, present as rutile and ilmenite in the undigested sand, was processed through Wilfley table. A concentrate containing 38% TiO2 with 47.30% recovery was obtained. This concentrate was subjected to smelting with activated carbon in an extended arc plasma reactor. Titanium carbide was formed as a fused mass within 5 minutes.