Viscosity and Constitution of Slags Associated With Metallorthermic Extraction of Some Less Common Metals

Abstract

Slags resulting from aluminothermic reduction of oxides for production of less common metals and their ferroalloys contain a high percentage of alumina and have a high melting point as well as being highly viscous. Alumina exhibits both covalent and ionic bonding under different conditions. It is expected that high alumina slags may behave like silicate melts that contain silica having a covalent bond. Consequently, an exhaustive review on structural aspects of silicate melts, their viscosity, activation energy of viscous flow, conductance, etc., has first been made. The role of fluorides and other constituents on the viscosity of silicate melts has also been discussed. Some investigation results on viscosity measurement of some industrial blast furnace slags with and without titanium oxides and high titania slags have been presented to appreciate the structure of silicate melts. Review of relevant literature on the liquidus temperature and role of calcium fluoride on the thermo-physical properties of alumina-based melts has been made. Finally, the meagre information available on slag viscosity of some aluminothermic slags such as those of FeTi, FeCr, FeSiZr, and FeNb has been furnished. © 1990, Walter de Gruyter. All rights reserved.