The viscosities of CaO-SiO 2 -7MgO-TiO 2 -12Al 2 O 3 (wt-%) slags (CaO/SiO 2 50?5-0?9, wt-% TiO 2 515-30) were investigated to promote understanding of the effect of TiO 2 and basicity (CaO/SiO 2 ) on the viscous behaviour of slags containing TiO 2 . In practice, these experimental results are significant for the blast furnace (BF) processing of vanadium-titanium magnetite ore and for controlling the selective crystallisation of Ti bearing BF slags. The slag viscosity was found to decrease with increasing TiO 2 content at a fixed basicity. The degree of viscosity decrease with increasing TiO 2 content diminishes in the slag with higher basicity or higher TiO 2 content. An increase in the basicity lowers the viscosity of slags. The apparent activation energy of viscous flow of slags decreased with additions of TiO 2 and increasing basicity. The Urbain model was empirically modified based on the present experimental data, which can be used to predict not only quinary Ti bearing slags but also quaternary and low Ti bearing slags.

In the present paper, a high titanium molten (high Ti) slag was employed as an additive to modify the titanium bearing blast furnace (Ti-BF) slag in order to investigate the influence of the addition of high Ti slag on the crystallisation behaviour of the Ti-BF slag. The variation in the Ti enriched phase and the precipitation behaviour of the Ti enriched phase in the Ti bearing slag were studied in this paper. The Ti bearing slag in this paper was composed of different proportions of high Ti slag and Ti-BF slag. A combination of X-ray powder diffraction, scanning electron microscope equipped with energy dispersive X-ray spectroscope and optical microscopy was applied to determine the crystal structure, clarify the chemical composition and observe the morphology of the Ti enriched phase. It was found that the Ti enriched phase transformed from CaTiO 3 to Mg 4 Al 2 Ti 9 O 25 with the addition of high Ti slag. When the Ti bearing slag contained 60 wt-% high Ti slags, Mg 4 Al 2 Ti 9 O 25 became the only Ti enriched phase, and it could crystallise completely when the slag was held at 1450uC for 25 min. The formation mechanism of Mg 4 Al 2 Ti 9 O 25 is also discussed in this paper. Keywords: Precipitation behaviour, Mg 4 Al 2 Ti 9 O 25 crystal, Ti bearing blast furnace slag, High titanium molten slag ß 2012 Institute of Materials, Minerals and Mining Published by Maney on behalf of the Institute