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The viscosities of high alumina blast furnace slags were experimentally determined by the rotating cylinder method using the Brookfield digital viscometer model LVDV-II+ pro. Two different slag systems were considered for the current study, the CaO-SiO 2 -MgO-Al 2 O 3 quaternary and the CaO-SiO 2 -MgO-Al 2 O 3 -TiO 2 quinary system. Experiments were conducted in the temperature range of 1650 to 1873 K. The effects of temperature, basicity, TiO 2 , and silica activity of slags on viscosity were studied. The viscosity decreases with basicity for high alumina blast furnace slags with basicity in the range of 0.46 to 0.8. At high basicity (~0.8), slag viscosity decreases even with a small amount of TiO 2 (~2 pct) addition in the slag. With an increase in silica activity in the range of 0.1 to 0.4, the slag viscosity increases, the increases being steeper below the liquidus temperature.

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Most refining reactions in steelmaking involve oxidation of impurity element(s). The product(s) of oxidation either dissolve in the slag or escape as gaseous phase. The activities of oxygen in the metal (h O ), and that of ''FeO'' in slag (a FeO ), are major factors controlling these chemical reactions. The activities of oxygen and ''FeO'' are thermodynamically related, provided equilibrium distribution of oxygen between the slag and the metal is attained. This enables direct estimation of one parameter from the other. A thorough knowledge of the variation in activity of FeO, and factors affecting the same, is therefore of great importance in the process metallurgy of steelmaking. The present work experimentally measures the activity of FeO in steelmaking slags and attempts to develop a correlation for estimation of c(FeO) as a function of temperature and chemical composition of the slag.

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In the present work, the reaction between a molten iron drop and dense alumina was studied using the X-ray sessile-drop method under different oxygen partial pressures in the gas atmosphere. The changes in contact angles between the iron drop and the alumina substrate were followed as functions of temperature and varying partial pressures of oxygen in the temperature range 1823 to 1873 K both in static and dynamic modes. The results of the contact angle measurements with pure iron in contact with dense alumina in extremely well-purified argon as well as under different oxygen partial pressures in the gas atmosphere showed good agreement with earlier measurements reported in the literature. In the dynamic mode, when argon was replaced by a CO-CO 2 -Ar mixture with a well-defined in the gas, the contact angle showed an initial decrease followed by a period of nearly constant contact angle. At the end of this period, the length of which was a function of the imposed, a further steep decrease in the contact angle was noticed. An intermediate layer of FeAl 2 O 4 was detected in the scanning electron microscope (SEM) analysis of the reacted substrates. An interesting observation in the present experiments is that the iron drop moved away from the site of the reaction once the product layer covered the interface. The results are analyzed on the basis of the various forces acting on the drop.