Effect of TiO2 and BaO on viscosity and potassium removal capacity of blast furnace slag

In order to increase the utilization rate of vanadium–titanium magnetite in blast furnace smelting, the viscosity and potassium removal capacity of CaO–SiO₂–Al₂O₃–MgO–BaO–TiO₂ slag (CaO/SiO₂ = 1.05, 1–5 wt.% BaO, 2–20 wt.% TiO₂) were studied for slag optimization using the cylinder method and slag–metal equilibrium technique, respectively. Also, the structural properties of the slag were characterized by Fourier transform infrared spectroscopy. The concept of “a ring structure of Ti–O–Si” was proposed to express the change in the viscosity of the blast furnace slag. The results showed that the viscosity of slag increased with the increase in BaO content while the potassium removal capacity decreased. Furthermore, an increase in TiO₂ content from 2 to 20 wt.% resulted in a decrease in viscosity and an increase in potassium removal capacity. The Fourier transform infrared spectroscopy results showed that the charge compensation of Ba²⁺ can form complex aluminosilicate structure and increase the viscosity of slag. Meanwhile, with the increase in TiO₂ content, Ti⁴⁺ ions replace Si⁴⁺ in the silicon-oxygen tetrahedral structure, thereby reducing the degree of polymerization of the silicate network and decreasing the viscosity.