Reduction Mechanism of Fe_x0 - Graphite Composite under Elevating Temperature

摘要

Since iron ore-carbon composite permits rapid reduction reaction, its utilization is an effective method to reduce carbon dioxide emissions in ironmaking process. Major iron ores consist of Fe_2O_3, Fe_3O_4, and FeOOH, which require several reduction steps through Fe_xO to form metallic iron. In this study, Fe_xO, which has a certain solid solution range, was highlighted as an alternative iron source for the composite. It is because Fe_xO can be produced by a pre-reduction process of iron ores although it is not a major component of natural ores. The effect of the oxygen concentration of the Fe_xO and the mix-grinding time of the iron oxide and carbonaceous material on the reduction behavior of the composite was examined. The composite samples of Fe_xO with different oxygen concentrations, i.e., different x value and graphite were prepared and heated up to 1 200℃ under inert gas flow. The value of reduction degree was calculated from the concentration of gas generated from the composite. Reduction temperature decreases with increasing x value and the grinding time. In the case of a 3.6 ks-grinding, reduction reaction of the composite with a low x value proceeded homogeneously, while reduction of that with a high x value proceeded topochemically.