Study on the rapid titanium–iron separation mechanism in titanomagnetite driven by flash Joule heating

Abstract

To address the complex properties of this titanomagnetite sample and the high energy consumption and pollution associated with conventional reduction roasting, this study developed a rapid and eco-friendly process for reducing ilmenite using Joule heating. Results show that as the current intensity increased from 60 A to 150 A during reduction roasting, the reduction rate of magnetite significantly improved within a short period. Metallic iron formation progressively increased, while impurity content in ilmenite and titanium-bearing phases decreased. Consequently, optimal separation and recovery of titanium and iron from the raw ore were achieved at 150 A current intensity, 30 % graphite dosage, and 15-second reduction time, effectively lowering the titanium grade in the sample. Kinetic studies revealed that the three-dimensional diffusion model accurately describes titanomagnetite decomposition under Joule heating, with a calculated activation energy of 30 kJ/mol—far lower than that of conventional roasting methods. Furthermore, energy consumption and carbon emission comparisons demonstrated that Joule heating roasting consumes only 1/54 of the energy required by traditional methods, with significantly reduced carbon emissions. Thus, Joule heating reduction roasting not only enhances reaction efficiency and product quality but also demonstrates clear advantages in energy savings and environmental impact. And finite element simulations and first-principles DFT calculations further indicate that under an applied electric field, the energy band structures of graphite and ilmenite undergo significant changes: narrowed bandgaps facilitate electron transitions and free charge carrier formation, thereby accelerating the reduction reaction. These findings provide a novel technological pathway for the efficient utilization of titanomagnetite resources.