Microscopic behavior and metallic iron morphology from reduction of iron oxide by CO/H-2 in a fluidized bed

摘要

Fe2O3 particles reduced by CO or H-2 exhibit different metallic iron morphology. To determine the mechanism of metallic iron formation during the reduction of iron oxide particles by CO/H-2 in a fluidized bed, an innovative multiscale method was used. This method was validated by experimental results. Density functional theory calculations demonstrate that the CO molecule has a strong stretching effect on the iron ion of wustite in the vertical direction, but the H-2 molecule has no directional force on the structure of wustite. The energy released from CO reduction is used to overcome the energy barrier of iron ion diffusion. However, H-2 addition will hinder iron ion diffusion by consuming energy. By analysis of the thermogravimetric curves of Fe2O3 reduction, it was found that the adsorption ability of H-2 on the surface of FeO is weaker than that of CO. However, the reduction rate is higher under H-2 atmosphere, according to Langmuir adsorption isotherm theory. The morphology of metallic iron during the reduction of iron oxide particles by CO/H-2 was observed with a scanning electron microscope equipped with an energy dispersive X-ray spectroscopy detector