Optimal Process Parameters for Direct Carbothermal Reduction of Vanadium–Titanium Magnetite in a Rotary Kiln

Abstract

Direct reduction in rotary kiln plays a crucial role in the reduction and smelting of vanadium–titanium magnetite. The effect of the process parameters on the metallization rate and reaction mechanism during the reduction process in a rotary kiln is investigated. The results indicate that the optimal process parameters for direct reduction of vanadium–titanium magnetite in a rotary kiln are as follows: a reduction temperature of 1150 °C, reduction time of 4 h, carbon ratio 1.2, particle size of vanadium–titanium magnetite as 8–12 mm, and particle size of pulverized coal of <8 mm. During the direct reduction of vanadium–titanium magnetite, favorable conditions such as absence of smelting phenomenon on the surface of the reduction products, high metallization rate, and high quality of direct reduction iron are achieved. Through direct reduction, the transformation process of iron oxide in vanadium–titanium magnetite is Fe3O4 → iron oxide → Fe, and the transformation process of titanium–iron oxide is Fe9TiO15 → Fe2.75Ti0.25O4 → Fe2.5Ti0.5O4 → iron titanate → Fe. In addition, vanadium and ferrochrome oxides undergo reduction to form oxides or carbides.