Solid-state reduction kinetics and mechanism of pre-oxidized vanadium–titanium magnetite concentrate

The solid-state reduction kinetics of pre-oxidized vanadium-titanium magnetite concentrate was studied. The phase and microstructure of the reduction product were characterized by XRD, SEM and EDS methods, based on which the mechanism of the solid-state reduction was investigated. The results showed that using coal as reductant at 950-1100 °C, the solid-state reduction of the pre-oxidized vanadium-titanium magnetite concentrate was controlled by interface chemical reaction and the apparent activation energy was 67.719 kJ/mol. The mineral phase transformation during the reduction process can be described as follows: pre-oxidized vanadium-titanium magnetite concentrate → ulvospinel → ilmenite → FeTi2O5 → (FenTi1-n)Ti2O5. M3O5-type (M can be Fe, Ti, Mg, Mn, etc) solid solutions would be formed during the reduction process of the pre-oxidized vanadium-titanium magnetite concentrate at 1050 °C for 60 min. The poor reducibility of iron in M3O5 solid solutions is the main reason to limit the reduction property of pre-oxidized vanadium-titanium magnetite concentrate.