Influence of reduction conditions on the expansion and microtexture of sintered hematite compacts during the transition to magnetite

Permeability in the blast furnace shaft is adversely affected by low-temper ature reduction degradation of sinters. The fundamental cause of this is th e expansion of the iron oxide phase resulting from the reduction of hematit e to magnetite. The present study shows that expansion behavior during the hematite/magnetite reduction step and the resulting microstructure are stro ngly influenced by the reduction temperature (partial oxygen pressure), the reducing agent and the nature of the hematite. The reduction rate is of mi nor importance. A reduction mechanism is proposed that can explain the dila tion behavior and the magnetite microstructure. The results provide better insight into the reduction degradation behavior.