Progress in Melting-Flow Characteristics of Titanium-Bearing Blast Furnace Slag

Vanadium–titanium magnetite is a critical strategic polymetallic mineral resource in China, and blast furnace smelting represents the dominant large-scale industrial process for its utilization. The melting and fluidity properties of titanium-bearing blast furnace slags (TBFS) directly govern stable blast furnace operation and the recovery efficiency of vanadium–titanium resources. This paper systematically reviews research progress on the melting and flow characteristics of TBFS. The influences of main components (TiO2, CaO/SiO2, MgO, Al2O3), trace oxides, and strongly reduced products TiC and TiN on slag mineral phases, break point temperature (TBr) and viscosity are summarized. Combined with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman characterizations and FactSage thermodynamic calculations, the inherent mechanisms are revealed from the perspectives of microstructural network polymerization and crystalline phase precipitation. TiO2 exerts dual effects: it depolymerizes the silicate network to reduce slag viscosity while promoting the precipitation of high-melting-point perovskite. Al2O3 intensifies network polymerization and impairs slag fluidity. MgO, basicity, MnO and BaO can decrease slag viscosity. Solid particles of TiC and TiN generated under the strong reducing atmosphere inside blast furnaces drastically increase slag viscosity and Tbr. This paper proposes that future research should focus on slag systems with higher TiO2 contents, so as to provide theoretical support for the high-efficiency blast furnace smelting of VTM and resource utilization of titanium-bearing slags.