Kinetics of reduction of titano-magnetite powder by H2

摘要

The reduction of titano-magnetite powder containing 56.9 mass% of iron and 9.01 mass% of TiO2 with H2-Ar gas mixtures was investigated in isothermal experiments by using thermo-gravimetric analyzer (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM). TGA measurements were carried out from 967 to 1173K under the hydrogen partial pressure(PH2)range from 50.5 to 101kPa. The results showed that under the conditions of lower temperatures and lower hydrogen partial pressures, the reductive reaction was very slow. Nevertheless, the reaction rate increased with the increasing temperature and(PH2)It was found that the double reactions, reduction of titano-magnetite to produce wüstite and ilmenite and reduction of wüstite and ilmenite to generate iron and titanium-containing phase, occurred simultaneously during the reduction of titano-magnetite with hydrogen. The experimental results indicated that the hydrogen diffusion in wüstite and ilmenite layer was the rate controlling step for the first reaction (reduction of titano-magnetite to produce wüstite and ilmenite), the reduction rate of the second reaction (reduction of wüstite and ilmenite to generate iron and titanium-containing phase) was controlled by interfacial chemical reaction. The apparent activation energies were as high as 98kJ/mol and 115kJ/mol for the first and second reaction respectively.