2004 Volume 44 Issue 6 Pages 999-1005
The reduction of titania-ferrous ore (ironsand) containing 57.2 mass% of iron and 7-8 mass% of TiO2 was investigated in isothermal experiments using H2-Ar gas mixtures in a laboratory fixed bed reactor in the temperature range from 973 to 1 373 K. The degree of reduction was measured using an on-line Dew Point sensor and the samples in the course of reduction were characterized using SEM and XRD analyses.
The complete reduction of iron oxide in the ore by 25vol%H2-Ar was achieved within 60 min at temperature higher than 1 123 K. At 1 173 K, the reduction rate increased with hydrogen content in the reducing gas up to 25 vol%H2. The composition of samples after 2-h reduction by 25vol%H2-Ar depended on the reduction temperature. Below 1 073 K, the final sample contained iron and iron-titanium oxides. At temperatures above 1 173 K, the final sample was composed of iron and titanium oxide. The reduction path at temperatures above 1 173 K is suggested as follows:
Fe3-xTixO4 → ‘FeO’+Fe3-x-δTix+δO4 → Fe+Fe3-x-δTix+δO4 → Fe+xTiO2, (0<δ<1−x)