ON THE VISCOSITY OF MOLTEN SLAGS (II)

To clarify the effect of MgO on the viscosity of blast furnace slag, viscosities of synthetic CaO-SiO2-Al2O3-MgO slags were measured by the rotating inner-cylinder viscosimeter as in the case of the first report. (Tetsu-to-Hagane, Vol. 38, 1952, 12) Iso-viscosity lines at 1, 500 and 1, 600°C are drawn on the diagram (Fig. 1, 2, 3)When MgO was added to GaO-SiO2 slag, the viscosity decreased with increasing amounts of MgO up to about 20%, but thereafter increased. The region of low viscosity in Cao-SiO2-MgO slag was greater than that in the CaO-SiO2-Al2O3 slag.When MgO was added to CaO-SiO2-Al2O3 slag, the viscosity decreased and moreover changein viscosity at constant temperature caused by the change of slag composition became small, but these beneficial effects of MgO were less noticeable than those reported by the previous investigator. With respect to the fluxing quality, MgO had nearly as much influence in reducing slag viscosity as CaO or slightly less.