Reduction behaviors of vanadium‑titanium magnetite with H2 via a fluidized bed

Abstract

Vanadium‑titanium magnetite, a kind of composite ore with iron, vanadium and titanium, has not been utilized on large scale by steel plants. An efficient and clean utilization technique for vanadium‑titanium magnetite based on fluidized bed hydrogen reduction was developed in present study. The effect of reduction temperature, H2 concentration, reduction time and gas flow rate on the metallization degree of the reduced product were studied. The phase compositions and microstructures of sample were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Experimental results indicated that a metallization degree of 91.30% was obtained under the optimal conditions of reduction temperature of 850 °C, H2 concentration of 80%, reduction time of 30 min and gas flow rate of 900 mL·min−1. As the number of metallic iron grains increased, adjacent metallic iron grains gradually aggregated and formed flakes. While, the metallic iron grains precipitated by reduction of raw ilmenite gathered into strips. It is noteworthy that no intermediate phase wustite is detected in all reduced samples, which may be due to the wustite is immediately reduced or decomposed after being formed. Therefore, the possible reduction paths of titanomagnetite are suggested as follows: (1) Fe3-xTixO4 → Fe + FeTiO3 → Fe + TiO2, (2) Fe3-xTixO4 → FeO + FeTiO3 → Fe + TiO2, 0.5 < x < 1.