The influence of basicity and TiO2 on the crystallization behavior of high Ti-bearing slags
China has abundant vanadium–titanium magnetite resources. It is important to extract the Fe, Ti and V elements from vanadium–titanium magnetite by recycling. The HIsmelt smelting reduction process is an effective method to smelt vanadium–titanium magnetite. In the present study, the phase composition of the high-titanium slag produced under different temperature and composition conditions under the HIsmelt smelting reduction process was first analyzed via thermodynamic calculations. An experimental scheme was further designed to study the influence of different factors on the crystallization behavior of the high-titanium slag. The thermodynamic calculation results showed that perovskite and pseudobrookite are the main enrichment phases of the high-titanium slag during the slag cooling phase. With the increase in the TiO2 content, the main titanium-rich phase changed from perovskite to pseudobrookite. As the basicity decreased, the main titanium-rich phase that precipitated was pseudobrookite. The experimental results were basically consistent with the thermodynamic results. With the decrease in the TiO2 content, the main titanium-rich phase in the slag evolved from plate-like anosovite to columnar or dendritic perovskite, and the size of the precipitated crystals decreased. When the content of TiO2 decreased to 23%, the precipitate morphology of some perovskite crystals changed from columnar to dendritic. As the basicity of the slag decreased, the titanium-rich phase in the slag changed from perovskite to anosovite. When the basicity of the slag was 0.8, anosovite became the only titanium-rich phase. Anorthite was also formed and had a thin rod shape. In addition, with the decrease in the MgO/Al2O3 ratio, the composition of anosovite changed from (MgTi2O5)0.8·(Al2TiO5)0.2 to (MgTi2O5)0.6·(Al2TiO5)0.4. The research results provide a reference for the further understanding of the crystallization behavior of the high-titanium slag produced by the HIsmelt smelting reduction process and the utilization of the titanium-rich slag as a resource.