Experimental studies of the viscosities in the CaO-Fe n O-SiO 2 slags
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I.
INTRODUCTION
THE understanding and optimization of the metallurgical processes require access to accurate data of the physical properties of slags. Viscosity is one of the most important properties in the case of metallurgical melts, in view of its direct effect on the kinetic conditions of the processes, and is one of the key factors to be taken into consideration in process modeling. The oxides commonly employed in steel slags are Al2O3, CaO, Cr2O3, MgO, MnO, SiO2, and FenO. Some of these oxides are also important components in the slags pertaining to copper metallurgy. Great efforts have been made to generate viscosity data for various slags since the early 1930s. However, the data available are still too few to meet the high demands of the advanced technology today. Recently, a mathematical model for estimation of viscosities of multicomponent melts has been developed at the present laboratory.[1] The model makes it possible to express viscosity as a function of temperature and composition for multicomponent systems. The model has been applied successfully to various metallic and ionic melts. In light of this model, a long-term project is currently being carried out at the Division of Theoretical Metallurgy to get a complete description of viscosities in the multicomponent system, Al2O3-CaO-Cr2O3-FeO-Fe2O3-MgO-MnO-SiO2. A reliable description for this multicomponent system necessitates accurate experimental data for corresponding lower-order systems. In the present work, the viscosities in the CaO-FenO-SiO2 system are studied. The study of the viscosities in the CaO-FenO-SiO2 ternary itself is important, even from a practical viewpoint. In the secondary steelmaking processes, CaO-based slags are usually employed. These slags very often contain SiO2 and even FenO. To the knowledge of the present authors, the experimental viscosity data are only available at 1673 K for this system.[2–5] While Bodnar et al.[2] and Williams et al.[3] reported viscosity values for only one and two slag comF.-Z. JI, Research Student, DU SICHEN, Associate Professor, and S. SEETHARAMAN, Professor, are with the Division of Theoretical Metallurgy, Royal Institute of Technology, S-100 44 Stockholm, Sweden. Manuscript submitted November 13, 1996. METALLURGICAL AND MATERIALS TRANSACTIONS B
positions, respectively, Johannsen and Sishkov[4] and Kozakevitch[5] constructed the isoviscosity lines at 1673 K. The agreement between the results of these works[2–5] is not satisfactory. The aim of the present work is to sort out this discrepancy and, at the same time, provide a base with accurate experimental data for reliable model extrapolations. The application of the viscosity model to the ternary system CaO-FenO-SiO2 requires the experimental information of the relevant unary and binary systems. In order to verify the experimental data of the binary systems available in the literature and to examine, at the same time, the reliability of the present experimental method, viscosity measurements in the case of one composition in each of the bin
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