Physicochemical properties of the CaO-SiO2-B2O3-MgO-Al2O3 slags system

Abstract

The study of the physicochemical properties of the CaO-SiO2-B2O3-MgO-Al2O3 slags system was carried out using the method of simplex lattices for experimental planning, the HSC 6.1 Chemistry software (Outokumpu) and the method of electro-vibration viscometry. It is shown that the studied oxide system containing 25% Al2O3, 8% MgO and 1–10% B2O3 has a low viscosity in the range of 0.05–0.4 Pa·s with a basicity of 2–5 at temperature 1500–1600 °C. It was found that an increase in the basicity of the slag from 2 to 5 in the boron oxide concentration range of 1–10% leads to an increase in the sulfur distribution coefficient from 1 to 20 and a decrease in the sulfur content in the metal from 0.017 to 0.0015%. Consequently, an increase in the basicity of the slag favourably affects the development of the metal desulfurization process. In the area of basicity 2–3, the boron interphase distribution coefficient decreases from 450 to 100 with an increase in the B2O3 content from 1.0 to 10.0% in slags, and the boron concentration in the metal increases from 0.005 to 0.02%. An increase of the basicity to 5.0 shows a high degree of boron reduction from slag to metal. The results of the laboratory experiment confirmed the results of thermodynamic modelling.