Physicochemical properties of the СаО–SiO2–B2O3–2 % Cr2O3–3 % Аl2O3–8 % МgO slag system.

Abstract

Using the simplex lattice method of experiment planning lattices, the physicochemical properties of slags of the СаО–SiO2–B2O3–2 % Cr2O3–3 % Аl2O3–8 % МgO oxide system are studied in a wide range of chemical composition (CaO/SiO2 = 1.0–2.5; 0–6 % B2O3), i. e. viscosity, crystallization onset temperature, equilibrium distribution of sulfur between slag and metal. Mathematical models of slag properties dependence on its composition are constructed in the form of a reduced polynomial of the third degree. The results of mathematical modeling of the sulfur removal reaction and experimental studies of the viscosity of slags and their crystallization onset temperatures are presented graphically in the form of “composition–property” diagrams. It’s found that the addition of up to 6% boron oxide significantly liquefies slags and reduces the temperature of the onset of crystallization, while maintaining the possibility of deep desulphurization of the metal. For effective metal processing, the composition range of slags with a basicity of 2.0–2.5 and a content of 4.0–6.0 % boron oxide is optimal. These slags have high liquid mobility (viscosity of the formed slags does not exceed 0.3 Pa•s) and provide the sulfur content in the metal not more than 0.003–0.004 %. The slags of this area are homogeneous, since their crystallization onset temperature doesn’t exceed 1500 °C. Experimental studies of metal desulfurization under the basic slags of the studied local simplex confirmed the data characterizing the influence of the boron oxide content and the basicity of the formed slags on their viscosity and its role in the efficiency of the desulfurization process.