This study presents an effective and cleaner process with hydrogen-rich gases that uses oxidation roasting followed by gas-based direct reduction and melting separation to recovery iron, titanium, vanadium, and chromium from Hongge vanadium titanomagnetite (HVTM). The process parameters were systematically investigated and determined to be roasting temperature at 1200°C, roasting time of 15 min, reduction temperature at 1050°C, volume ratio of H₂ to CO of 2.5, melting temperature at 1580°C, melting time of 30 min. Under optimized conditions, after melting separation, the recovery rates of iron, titanium, vanadium, and chromium were 97.9, 89.8, 96.7, and 97.8%, respectively. Furthermore, the melting separation mechanism was determined. The separated iron is a clean raw material for steelmaking and the Ti-rich slag can send for further processing to recover titanium. This study aims to provide a theoretical and technical basis for the comprehensive utilization of HVTM.

As part of the development of a novel and clean smelting process for the comprehensive utilization of Hongge vanadium titanomagnetite (HVTM), the objective of this study was to investigate the influence of MgO on the oxidation and induration of HVTM pellets (HVTMP). The results showed that the oxidation degree and compressive strength decreased significantly with the increase in added MgO, which corresponded to the increase in porosity. MgO reacted with Fe₂O₃ to form Mg–Fe solid solution. The evolution in microstructure was explained by the interactions between MgO and Fe₂O₃ at the grain boundaries. Mg²⁺ diffusion affected the oxidation and induration, and cracks were formed, resulting in the uneven distribution of grains and the inhibition of hematite recrystallization. Furthermore, the grain size decreased significantly. Based on the results, we proposed a diagram to describe the mechanism, which showed that MgO had a negative effect on the oxidation and induration of HVTMP.

To develop a novel and clean smelting process for the comprehensive utilization of Hongge vanadium titanomagnetite (HVTM), this work determined the influence of B2O3 on the oxidation and induration process of HVTM pellets (HVTMP). The oxidation degree, compressive strength, porosity, crystalline phase, microstructure, and induration degree of HVTMP were comprehensively investigated, and the relevant mechanisms were discussed. The results indicated that B2O3 decreased the oxidation degree and porosity of HVTMP, while the compressive strength was clearly enhanced. Increasing the amount of B2O3 did not significantly affect the crystalline phase, but it decreased the XRD peak intensity. The induration degree appreciably increased after the addition of B2O3 because it favored the generation of liquid phases and increased the average grain size by creating a dense and continuous bonding structure. Additionally, B-rich phases were mainly uniformly distributed in the liquid phases along the grain boundaries. Based on the experimental results, the induration mechanism of HVTMP with different amounts of B2O3 was proposed. This study provides a theoretical and technical foundation for the effective production of HVTMP.

The Bi2Se3–In2Se3 layered system has garnered significant attention and extensive research due to its versatile properties, yet its structural properties and phase stability remain elusive. Here, using first-principles calculations with van der Waals interactions, we systematically study the phase stability and transition behavior of (BixIn1−x)2Se3 alloys. Our results reveal a contrasting stability profile between Bi2Se3 and In2Se3, with the former exhibiting a distinct preference for the β phase over the α phase, while the latter shows similar stabilities in both phases, thus partially addressing previously reported ground-state inconsistencies. Exploring composition–structure relationships, we demonstrate that Bi incorporation in low concentrations stabilizes the β phase, consistent with early experimental observations. Further analysis based on the cation orbital properties indicates that the preference of Bi for octahedral sites over tetrahedral ones drives the small critical composition for the α→β phase transition. This work enhances our understanding of phase stability in (BixIn1−x)2Se3 alloys, providing insights for future design of monophasic materials and advanced applications.