Effect of basicity and chromium oxide on the viscosity of boron-containing slags

Abstract

The main diluent for chromium-containing slags is CaF2. However, fluorspar disadvantages make it necessary to search for a replacement. As a substitute, boron oxide allows to improve slag physical properties and environmental situation. The paper presents the experimental study results of the chemical composition and temperature influence on viscosity of slags of CaO-SiO2-Cr2O3 system containing 8% MgO, 3% Al2O3 and 6% B2O3. It was found that a slag free of chromium oxide with basicity of 1.0 has a sufficiently high fluidity of 0.2-0.6 Pa•s in a wide temperature range of 1200-1350 C, due to high concentration of low-melting phases, reaching 22%, and only 11 % high-melting. A slag with 18% Cr2O3 and the same basicity retains a low viscosity of 0.1-1.0 Pa•s but at higher temperature of 1450-1570 C due to increase in high-melting compound content to 27%. The viscosity of a slag with basicity of 2.5 without chromium oxide is 0.07-1.0 Pa•s in a narrow temperature range of 1650-1700 C and 0.14-1.0 Pa•s for a 'shorter' slag with 18% Cr2O3 and same basicity in even narrower range of 1650-1670 C. These slags have the highest high-melting phase content of about 50%. © Published under licence by IOP Publishing Ltd.