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%.
Highlights
The main method for the production of low-carbon stainless steel in the world is argon oxygen decarburization (AOD), which consists of 2 periods: oxidation and reduction
The authors [2,3,4] note that low viscosity slags are in a narrow range of compositions, the possibility of reducing the viscosity of these slags with the addition of fluorspar was studied [5, 6]
Thermodynamic modeling of the phase composition of the prototypes was carried out using the HSC Chemistry 8.03 software package, which allows one to calculate the equilibrium compositions and quantities of the products formed according to the Gibbs energy minimization algorithm based on the concepts of metallurgical melts as ideal associated solutions [19]
Summary
The main method for the production of low-carbon stainless steel in the world is argon oxygen decarburization (AOD), which consists of 2 periods: oxidation and reduction. B2O3 has a low melting point and forms low-melting eutectics with the main components of the slag, for example, MgO‧B2O3 (melting point 988°С), CaO‧B2O3 (melting point °С) and others. This oxide is actively used in blast furnace production, ladle metallurgy and in continuous casting of steel [11,12,13,14,15,16]. The number of studies studying the effect of B2O3 on the physicochemical properties of chromium-containing slag [17] is extremely limited
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