Modeling of High Alumina Blast Furnace Slag

Abstract

Indian blast furnaces are running of high alumina slag due to high alumina to silica ratio in ores. slag mainly contains lime(CaO), silica (SiO2),alumina(Al2O3) and magnesia(MgO) along with smalleramount of FeO, MnO, TiO2, K2O and S. The flow characteristics of the slag determine size, shape and area of the cohesive zone in the furnace. The cohesive zone in the furnace acts as a gas distributor and its area let down the furnace diminishes the high temperature zone in the furnace, which moves the lime dissemination circle to lower levels.In the present work, softening and melting test were conducted for CaO-SiO2-MgO-Al2O3 quaternary slag system, to determine theflow characterstics of synthetic slag using a Leitz high temperature microscope as per German standard 51730. Empirical equations are developed to predict softening temperature (ST), hemispherical temperature (HT) and flow temperature (FT).Slag viscosity was also determinedusing Iida modelwrt C/S ratio, MgO and temperature ranging from 1623K and 1823K which covers the liquidus temperature.viscosity decreases with increase of MgO content, an increase of temperature having a diminishing effect on decreasing of viscosity at higher MgO content. Increase in C/S ratio decreases viscosity because CaO acts as network modifier