Effect of Basicity on the Reduction Disintegration Behavior of Vanadium-Titanium Magnetite Pellets Under the Hydrogen-rich Atmosphere
摘要
Research on vanadium-titanium magnetite (VTM) pellets has focused on gas-based shaft furnaces and acidic pellets, and few studies have investigated the reduction disintegration behavior of VTM flux pellets. In this paper, the effects of basicity, reduction temperature, and gas composition on the reduction disintegration behavior of VTM pellets were investigated, and the reduction disintegration mechanism was elucidated. It was shown that the ilmenite diffraction peaks were gradually enhanced when the basicity (R, CaO/SiO2) was greater than 0.9, indicating that CaO participates as a reactant in the reduction of Fe2TiO4 to FeTiO3 by CO, forming a thermodynamically more stable new product (CaTiO3), which drives the reaction toward a thermodynamically more favorable direction. The reduction path of Fe2TiO5 at high-basicity was Fe2TiO5 → Fe2TiO4 → FeTiO3, and the sharp expansion and contraction of the cell volume may account for the more severe disintegration of VTM pellets at high-basicity than that of conventional pellets. When the reduction temperature was 400 °C, there existed a large amount of unreduced hematite (titanium hematite), and the temperatures higher than 550 °C, the gradual generation of wustite slowed down the internal stress of the pellet. This was the reason why the reduction disintegration index (RDI) first increased and then decreased as the temperature increased. The RDI of VTM pellets gradually deteriorated with increasing H2 content.
Graphical Abstract