Effect of Metallic Iron on the Carburizing Rate of Reduced Ilmenite: An Analysis with Analytical-Grade Reagents
摘要
Metallic iron influences the carbothermic reduction of titanium oxides in ilmenite, thereby affecting the carburizing rate of the product. This study employs a CH4-H2 mixed gas to reduce various types of ilmenite and for the first time systematically investigates the mechanism by which iron impacts the carburizing rate during the reduction process. The results demonstrate that iron can catalyze the cracking of methane to generate more carbon and hydrogen, which enhances the reduction of ilmenite. Additionally, iron can dissolve carbon, leading to a phase change that modifies the aggregation state of iron. This alteration promotes volume contraction of the reduced ilmenite, subsequently affecting the carburizing rate of the product. From 1150 °C to 1225 °C, the increased solubility of carbon in iron facilitates its conversion from a solid state to an interconnected molten state, obstructing pore spaces. Concurrently, the high viscosity of molten iron hinders the effective utilization of dissolved carbon, leading to a reduced carburizing rate. As the temperature continues to rise, the fluidity of the molten iron increases, causing it to reaggregate and resulting in the reappearance of cavities. Moreover, molten iron can act as a diffusion pathway for carbon, improving the contact area between carbon and titanium oxides, which in turn promotes the formation of carbides.