Mechanism of Metastable Wustite Formation in the Reduction Process of Iron Oxide below 570°C

The possibility of metastable wustite below 570 degrees C during the reduction of iron oxides was discussed. There was uncertainty regarding the formation of metastable wustite in the reduction of hematite below 570 degrees C . Planar disregistry (1/delta) was employed to predict the probability of metastable wustite formation during the reduction process. The calculated results showed that the delta of wustite/magnetite is similar to that of iron/magnetite with plain and normal structures, but less than flake and finger structures. The difference in disregistry of different geometries of interfaces was suggested to be the principal driving force for the formation of metastable wustite. This implies that the formation of metastable wustite always accompanies the nucleation of iron structures with high d relative to magnetite. The latter structures form easily in supported iron, leading to the relatively common observation of metastable wustite in an iron catalyst. The analysis showed that the temperature range for metastable wustite formation 400 degrees C similar to 500 degrees C was most likely to occur where it created a predominance of flake and finger structures.