The effect of mechanical activation on the carbothermic reduction kinetics of hematite - graphite mixture

The effect of mechanical activation on structural changes and kinetics of carbothermic reduction of hematite with graphite was studied in this research. Hematite powder mixture with graphite (with stoichiometry ratio C/O=1) was milled for the time periods of zero to 50 hours, and the structural changes were studied using X ray diffraction (XRD). The effect of mechanical activation on the kinetics of hematite carbothermic reduction was studied by performing thermal analysis tests and by employing model-free and constant slope methods. The activation energy as well as the reaction mechanism was then determined. The results showed that by mechanical activation for a time period of 50 h, the activation energy is decreased from 387 kJ/mol-1 to 186 kJ/mol-1, and the starting temperature of the reaction is decreased from 1125 to 620°C. The Boudouard chemical reaction was determined as the rate controlling step.