Furnace smelting and extractive metallurgy of red mud: Recovery of TiO2, Al2O3 and pig iron

Abstract

Turkish red mud (bauxite waste) has been mixed with dolomite and coke, pelletized and sintered at 1100 degrees C, and finally smelted at 1550 degrees C to produce pig iron and a slag. The slag was leached with 30% H2SO4 at 90 degrees C. The leachate was diluted, ferric iron was reduced with SO2, and extracted with 5% D2EHPA solution in kerosene. Silica and Al2O3 were recovered from the remaining aqueous solution, while the organic extract was stripped with 10% Na2CO3 solution, finally hydrolysed and calcined to produce pigment-grade TiO2. The titanium recovery efficiency on the basis of slag weight was 84.7%. The extractive separation of titanium from both valencies of iron was investigated as a function of pH and time. A stoichiometric flowsheet for the whole process has been developed.