Kinetics of Reduction of Titano-magnetite Powder by H2

Reduction of titano-magnetite powder containing 56.9 mass% of iron and 9.01 mass% of TiO2 with H-2-Ar gas mixtures was investigated in isothermal experiments using thermo-gravimetric analyzer (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The reduction of titano-magnetite was proved to proceed via a dual reactions mechanism. The first reaction is reduction of titano-magnetite to wustite and ilmenite and the second one is reduction of wustite and ilmenite to iron and titanium-containing phase. It was found that the dual reactions occurred simultaneously during the reduction. The reduction kinetics of titano-magnetite was analyzed according to a dual reactions kinetic model and the results indicated that the gaseous species diffusion in product layer was the rate controlling step for the first reaction, and interfacial chemical reaction was that for the second reaction. The apparent activation energies were extracted to be 98 kJ/mol and 115 kJ/mol for the first and second reaction, respectively.