Abstract:
In iron oxide and carbon composite, many reactions such as the reduction of iron oxide, gasification of carbon, and so on occur simultaneously during heating. At higher temperature, it is well known the gasification of carbon is rete-determining step due to its large endothermic reaction. The rate of indirect reduction has been studied extensively. On the other hand, there are very few reports on the quantitative analysis on the direct reduction due to analytical difficulties, while it is important to understand the total reduction mechanism in detail. Further, the reaction mechanism of the composite using carbonaceous material with volatile matter is very complicate because various kinds of reducing gases generate at lower temperature. In this study, reduction mechanism of the composite at lower temperature range was evaluated.
When the reduction from Fe2O3 to Fe3O4 by solid graphite completes below 1000°C, the contribution ratio of the direct reduction in the total reduction is approximately 45%. Further, this contribution for the reduction from Fe3O4 to FeO is small. Hydrocarbon gas decomposes on iron oxide, and hydrogen gas and solid carbon generate. Decomposed carbon contributes to the reduction of iron oxide. And if decomposed temperature is high for reduction, the reduction reaction by hydrogen gas proceeds.
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