Effects of Preoxidation of Titania-Ferrous Ore on the Ore Structure and Reduction Behavior

摘要

The paper examined an effect of preoxidation of titania-ferrous ore (New Zealand ironsand) on the ore structure and reduction by carbon monoxide. The major phase in ironsand is titanomagnetite, Fe_3O_4-Fe_2TiO_4 solid solution, with spinel cubic structure. In the non-isothermal preoxidation titanomagnetite was oxidized to cubic maghemite and then transformed to rhombohedral titanohematite, Fe_2O_3-FeTiO_3 solid solution. Isothermal preoxidation of the ironsand at 1273 K transformed titanomagnetite to titanohematite and partly to pseudobrookite (Fe_2TiO_5), however, complete oxidation of Fe~(2+) to Fe~(3+) in titanomagnetite was not achieved in the experimental condition. The reduction of the titania-ferrous ore was investigated in non-isothermal and isothermal experiments using 75vol percent CO-25vol percent Ar gas mixtures in a laboratory fixed bed reactor. Samples in the course of reduction were characterized using XRD and EPMA. Preoxidation increased the rate of ironsand reduction.