Reduction mechanism of titanomagnetite concentrate by hydrogen

•The oxide impurities, especially magnesium oxide, can baffle the reduction of Fe2 + in TTM concentrate.•The reduced particle is a rough and porous structure with microscopic inhomogeneity.•The reduction path of titanomagnetite concentrate by H2–Ar gas has been proposed.•Temperature and reduction degree has an effect on the resistances of internal diffusion and interfacial chemical reaction.

Titanomagnetite concentrate was reduced by H2–Ar gas mixtures in a laboratory fixed bed reactor at the temperatures from 1123 to 1323 K. The effects of reductive conditions on the reduction and metallization degrees were studied, including reduction temperature, reduction time and hydrogen content. And the characteristics of reduced samples were analyzed by X-ray diffraction (XRD), backscattered scanning electron (BSE) and energy dispersive spectrometer (EDS). Results have shown that both the reduction and metallization degrees increased with the increase of temperature and hydrogen content. Due to the low iron oxides content and the high impurities content such as magnesium oxide that baffled the reduction of Fe2 + in TTM concentrate, the reduction degree of TTM concentrate is lower than that of TTM ironsand at the same reduction condition. Above 1123 K, the reduction is mainly controlled by interfacial chemical reaction in the whole reduction process and the reduction path is suggested as follows:Fe3−xTixO4→x+y−1FeO+Fe4−2x−yTixO4−y→x+y−1Fe+Fe4−2x−yTixO4−y→3−xFe+xTiO20