Characterization of Blast Furnace Slag

Abstract

Viscosity & flow characteristics of the Blast Furnace slag constitute twovery Important parameters for ensuring the smooth operation of the Blast Furnace
producing pig iron. Ideally, the Blast Furnace slag should neither be very viscous nor very fluid. A Viscous slag interferes with efficient slag- metal separation; while a slag with very low viscosity is more likely to interfere with the thermal balance of the Furnace & affect the retention time of the metal droplets in the slag affecting the slagmetal reactions/ exchanges. Flow characteristics in the Blast Furnace slag can provide a fair knowledge about the location & extent of the cohesive zone in the Furnace. The cohesive zone in the Furnace acts as a gas distributor & its place lower down the Furnace would create less probability for the softened slag for choking the Furnace. Also a cohesive zone lower down the Furnace would result in less Si pick up in the hot metal. The present work aims at characterizing the Blast Furnace slag on the basis of its viscosity and flow characteristics. Empirical equations are developed to predict the flow characteristics of Blast Furnace slag and the same was validated through further experimentation. The viscosity of the Blast Furnace slag (synthetic one prepared in laboratory in line with the compositional details as encountered in the industry) is determined for C/S (CaO/SiO2) variation, MgO content variation and TiO2 variation and along with that to the simultaneous variation of C/S ratio & MgO content. The compositional dependence of the slag viscosity is discussed at length.