Factorial design analysis of reduction of simulated iron ore sinter reduced with CO gas at 1000–1100°C

Although the influence of many impurities on the reduction process of iron oxide has been intensively studied, the magnitude of such impurities and their mutual interactions on the total degree of reduction are still not clear. In the current study, a 2³ factorial design was used to investigate the magnitude of manganese oxide, silicon oxide and temperature on the reduction process of iron oxide using CO gas as a reducing agent. A regression model was used to deduce a mathematical formulation to predict the influence of manganese oxide (up to 6.0 wt-%) and silicon dioxide (up to 7.5 wt-%) on the degree of reduction of simulated iron ore sinter in the temperature range 1000–1100°C. The results showed that temperature has the highest positive effect, while the interaction combination of SiO₂ and MnO₂ showed the highest negative effect on the degree of reduction. Silicon dioxide exhibited a higher individual negative effect on the degree of reduction than manganese oxide. The mutual interaction combination of SiO₂ or MnO₂ with temperature has small positive effect on the degree of reduction, while the interaction combination of the all parameters (SiO₂, MnO₂ and temperature) exhibited a small negative effect. The results of the models were found to be in good agreement with the experimental data of reduction of simulated iron ore sinter and natural iron ore containing different percentages of manganese and silicon oxides. The program Matlab was used to carry out the required calculations.