Evaluation of physical properties of blast furnace slag - Measurement of viscosity


In blast furnace, formation of slag and the mineralogical transformation that the slag undergoes during descend of burden inside the furnace, influence the quality of hot metal. It is known that the components of slag namely silica and alumina increase the viscosity whereas the presence of calcium oxide reduces the viscosity. The melting zone of slag determines the cohesive zone of blast furnace and hence the fluidity and melting characteristics of slag play a major role in determining the blast furnace productivity. Initially iron rich slag is formed and thereafter due to assimilation of CaO and MgO from flux, the composition of slag varies. As the slag trickles down, it assimilates silica and alumina of ash, generated from combustion of coke. The process of trickling down depends on viscosity of slag, which further is governed by the composition and temperature of the melt.


The objective of this activity was (a) characterization and measurement of viscosity of synthetically prepared blast furnace slags and (b) measurement of viscosity of as received blast furnace slags.



Preparation of some synthetic slag samples and measurement of their slag viscosity were carried out using high temperature viscometer. The data generated were compared with the model developed by Ray and Pal. The mean value of the measured data during heating and cooling cycles matched with the model fairly well.


High Temperature Viscometer