Effect of CaO Added with SiO2and/or Al2O3on Reduction Rate of Dense Wustite by Hydrogen

Abstract

The dense wustite plates containing CaO together with SiO2and/or Al2O3have been reduced isothermally in a stream of hydrogen at temperatures between 670 and 930°C. Reduction rate of the specimens added CaO together with SiO2or Al2O3, increases monotonously along with the increase of CaO addition at temperatures below 730°C. However, reduction rate at temperatures above 800°C of these specimens, and reduction rate of the specimens added CaO together with SiO2and Al203 shows lowering once with the increase of CaO addition, and then increases after lowering. In every case, when addition of CaO increases to a certain extent, reduction rate reaches close to the maximum rate obtained at the reduction of the specimen added CaO alone. A part of these added oxides are dissolved in FeO phase to make solid solution, and the rest form composite oxide phase and coexist with FeO phase. It is made clear that the reduction of FeO phase is affected mainly by oxides dissolved. Oxides dissolved in FeO phase are thought to cause changes in structure of reduced iron, and result significant effects on reduction rate of FeO. © 1989, The Iron and Steel Institute of Japan. All rights reserved.