Kinetics study of low-grade ilmenite fusion process using sodium hydroxide: Non-isothermal condition with model-free methods

The caustic fusion process is one of the alternative processes in titanium dioxide production from low-grade ilmenite ore. The kinetics of low-grade ilmenite ore caustic fusion using sodium hydroxide (NaOH: Ti ratio = 2:1 (w/w)) under inert atmospheric conditions were studied utilizing thermogravimetric analysis (TGA) at heating ratesof 5, 10, and 15 °C/minute. In a nitrogen atmosphere, the caustic fusion kinetic parameters were calculated using the model-free isoconversion methods of Friedman, FWO, and KAS. It was observed that as conversion (α) increases, Ea and log A decrease. Because of the pre-exponential factor's high value, the order of the reactions has no effect on the process. These methods calculated activation energy profiles of conversion values with results ranging from 8.7 to 149.11 kJ/mol. They varied in a sophisticated way based on the heating rate over a wide range. The fusion product's XRD analysis revealed that the minimum temperature for the formation of a large amount of sodium iron titanate is 850 °C.