The Effects of MgO and Al2O3 Content in Sinter on the Softening-Melting Properties of Mixed Ferrous Burden.

The softening-melting properties of mixed ferrous burden made from high-basicity sinter with increased MgO and Al2O3 content and acid pellets was investigated for optimization. The influences of MgO and Al2O3 are discussed with the aid of phase analysis. The results showed that, with decreasing MgO mass%/Al2O3 mass% in mixed burden, all the softening-melting characteristic temperatures decreased, which can be attributed to the low melting temperature and viscosity of the slag caused by MgO and Al2O3. The permeability of the melting zone deteriorated again when MgO mass%/Al2O3 mass% decreased to a certain content. The softening interval widened slightly at first and then narrowed, while the melting interval first increased slightly and then increased greatly later. It can be deduced that the softening properties were improved, but the melting properties were worsened. Under comprehensive consideration of its softening-melting properties, permeability, iron ore reduction and the thermal state of the blast furnace hearth, the optimal softening-melting properties of a mixed ferrous burden with MgO mass%/Al2O3 mass% of 0.82 is optimal.

Influence of TiO2, Al2O3, and Basicity on Viscosity and Structure of High Titanium-Bearing Blast Furnace Slag.

The viscosity of high-titanium blast furnace slag with different TiO2 content, Al2O3 content, and basicity was measured at 1653-1773 K using the rotational cylinder method. The phase composition of the slag is measured by XRD. Phase diagram of the slags is calculated by FactSage software. Ionic network structure of the slags is analyzed by FT-IR. Results show that TiO2 depolymerizes the silicate network structure, reducing viscosity at high temperature, while increasing Al2O3 content generates a more complicated silicate, increasing viscosity. Basicity affects viscosity, with higher basicity resulting in lower viscosity above 1733 K. Perovskite significantly affects the viscosity of slag. This study provides an in-depth understanding of the relationship between the composition and viscosity of high-titanium blast furnace slag, which is very important for improving production efficiency.