EFFECT OF TITANIA ON THE CHARACTERISTICS OF BLAST-FURNACE SLAGS

The objective of this study was to understand the effect of 1 - 2 % titania on the high-temperature properties of blast furnace slags containing high alumina and magnesium oxide. The viscosity and liquidus temperature of semi-synthetic blast furnace slags were measured using a viscometer and a hot stage microscope, respectively, and the data were used to develop a statistical model for predicting the liquidus temperature and viscosity of blast furnace slags. Samples of the titanium bearing accretions were collected during tearing-out of the hearths of Tata Steel's blown-out D and E blast furnaces. They were subjected to various physico-chemical analyses (e.g. chemical, XRD, optical microscopy, SEM and image analysis) in order to understand the mechanism of hearth protection. In the range of composition studied, the liquidus temperature is found to lie between 1365 to 1430-degrees-C and the viscosity, between 0.30 to 0.60 Pa . s. Increase in titania fluidizes the slag and also makes it easy-melting. The titanium bearing compounds in the slag show traces of TiC. TiN, Ti2N, TiO, Ti2O3, Ti3O5 and Ti5O9. A mechanism of formation of these precipitates is proposed in this paper.