Carbon-Enhanced Reduction and Nitridation of Ilmenite Concentrate with Ammonia Gas

Low-grade ilmenite has gradually become the primary raw material for titanium metal production. Low-temperature chlorination is an appropriate process for treating ilmenite with high magnesium and calcium oxide content, focusing on preparing titanium carbide or nitride as raw materials. Currently, the carbonizing and nitriding of ilmenite concentrate face challenges, including high temperatures, excessive energy consumption, and low reaction efficiency. In this study, the carbon-enhanced reduction–nitridation of ilmenite concentrate in an ammonia atmosphere was investigated. Thermodynamic and roasting experiments demonstrated that adding carbon significantly increases reaction efficiency, reduces NH₃ consumption, and shortens reaction time. When the reaction temperature reaches 1000 °C or higher, and the carbon addition (n_C/n_FeTiO3) is at least 3, the reaction efficiency is significantly improved. Carbon promotes the aggregation of metallic iron and prevents sintering, enhancing gas diffusion. It reacts with NH₃ to produce reactive gases (CH₄, HCN), with HCN substantially promoting the formation of TiN from titanium oxides.