The effect of titanium on the reduction of titanomagnetite

Abstract

To clarify the retardation effect of titanium on titanomagnetite in the reduction process, the electronic structure and chemical bonding properties of spinel-type titanomagnetite solid solution were calculated by a discrete-variational (DV)-Xα clusters method. From the computational results, electronic structure and chemical bonding properties of Fe-O bond in the cluster model were affected by the substitution of neighboring Ti ions. The neighboring Ti ions around Fe-O bond made Fe-O bond more ionic. This calculation result suggests that the low reaction rate of titanomagnetite in comparison with magnetite come from not only titanium oxide itself in titanomagnetite crystal structure but also the stabilizing factor of titanium to the neighboring Fe ions. In order to support the simulation results, the reduction experiments of titanomagnetite samples containing different TiO2 contents were conducted using thermogravimetric analysis under CO-Ar gas mixture at 1173 and 1373K, respectively. The titanomagneite samples containing higher contents of TiO2 showed the lower reduction degree. The retardation effect of titanium in the reduction process was more dominant at 1173K compared with 1373K. The characteristic of non-ideal solution of titanomagnetite behaved ideally with increasing temperature.