Gaseous Reduction Behavior of Powdered Iron Ore Sinter and Analysis on the Basis of Rist Model for Fixed Bed

Abstract

For the analysis of a blast furnace process, it is necessary to investigate the reduction behavior of iron ore sinter, which is the main source of an iron oxide charged into the blast furnace. It is impossible to accurately analyze the reduction behavior of the iron ore sinter without considering the existence of a quaternary calcium ferrite (CF), which has another reduction equilibrium different from hematite. From this point of view, the gaseous reduction behavior of powdered iron ore sinter has been investigated mainly at 1 173 K and the analysis has been conducted on the basis of a model derived by modifying Rist model for a fixed bed in consideration of CF. The hydrogen reduction behavior is found to be in reasonable agreement with the reduction curve calculated from the derived model at temperatures ranging from 1 073 to 1 273 K. Subsequently, in order to confirm the validity of the derived model, the hydrogen reduction behavior of a synthesized CF, hematite, and a mixture of the CF and hematite was investigated. The trend was observed that the reduction behavior of hematite and the mixture of the CF and hematite is almost the same and that the reduction behavior of the single CF sample has a delay for the others, in reasonably accordance with the relation shipderived from the model. Moreover, the reduction behavior can be almost explained by the derived model regardless of the mixture ratio of H 2 and CO in the ingoing gas under the present experimental conditions; the reduction progress has a delay by the difference of the reduction equilibrium by replacing H₂ with CO(–CO₂).