Gaseous Reduction Behavior of Primary Ilmenite at Temperatures Between 1273 K and 1473 K

We propose a hydrogen-based preliminary reduction process for primary ilmenite before the smelting process in titanium dioxide pigment production, because of its advantages of low energy consumption and carbon dioxide mitigation. The hydrogen-based gaseous reduction of primary ilmenite concentrate was investigated at temperatures between 1273 K and 1473 K (1000 °C and 1200 °C) in an H₂–CO atmosphere and compared it with the carbothermic reduction of secondary ilmenite. Between 1273 K and 1373 K, hydrogen reduction was faster than carbothermic reduction for the entire time of the reaction. However, at 1473 K, CO evolution by the Boudouard reaction caused the carbothermic reduction to be faster initially; however, hydrogen reduction was faster after 70 minutes. The phases of the final product by the gaseous reduction were metallic iron, TiO₂, and a pseudobrookite solid solution. Numerous cracks and pores were generated, and agglomerated iron was observed throughout the particles. The gaseous reduction reaction was controlled by a chemical reaction with an activation energy of 42 kJ/mol. For the subsequent smelting process, the use of ilmenite concentrate feeds reduced by hydrogen during the preliminary reduction process decreased the energy consumption and CO₂ emissions.