An Investigation on the Relationship between Structure and Viscosity of Silicate Slags

Abstract

The viscosity of molten slags pivotally influences high-temperature metallurgical processes in industrial operations. This important physical property at a given temperature depends upon the slag structure. In this work, the relationship between structure and viscosity of molten slags is investigated. To this end, the typical experimental techniques for viscosity measurement aresummarized, namely capillary method, falling-body method, rotating method, and oscillating method. We also present viscosity models that have been developed to predict slag viscosities. Raman spectroscopy is a powerful method to determine features of amorphous materials, including the types of atomic bond vibrations and their relative distribution. A group of synthetic slags in the SiO2-CaO-Al2O3 ternary system is considered with compositions close to industrial slags in silicon production. The Raman spectroscopy data is obtained within the wavenumbers on the order of 200–1300 cm−1. The Raman data provides access to the structural information (i.e., the depolymerization of melts), which is linked to viscosity. In order to discuss the relationship between structure and viscosity results for this group of slags, the viscosity values are adopted from the literature. The viscosity is found to be inversely proportional to temperature and the addition of basic oxides, due to the breaking of the silicate network.