Measurement of Viscosity of High Alumina Blast Furnace Slags by Statistical Approach

Abstract

Slag viscosity is an important process variable of the blast furnace process. The viscosity of molten slag is dependent basically on its chemical composition and on its temperature. Indian blast furnaces run into high alumina slag (Al2O3 >= 25%) due to high alumina/silica ratio in iron ore as well as sinter and high ash content in the coke. These slags are highly viscous which affects the gas permeability, heat transfer etc. In the present work slag viscosity was determined for CaO-SiO2-MgO-Al2O3 quaternary system using Iida model. Slag composition consists of MgO values between 4 and 10%, CaO/SiO2 between 0.9 to 1.2 and Al2O3 25%. The temperature range was between 1523 and 1723K which covers the liquidus temperature because the viscosity at this temperature will fluctuate greatly. The effect of CaO/SiO2, MgO and temperature on viscosity were studied. The results indicate that the viscosity decreases with increase in basicity and MgO content.