Abstract:To avoid slag sticking onto the ladle snorkel during the process of ladle alloying treatment station (LATS), the variation of the ladle slag viscosity before and after LATS refining process was studied. The additives including CaO+CaF2, CaO+B2O3 and Li2O were employed to decrease the viscosity of ladle slag. The rotary cylinder method was adopted in the viscosity testing experiments. The results showed that the viscosity of ladle slag was very high and further increased after LATS refining process, which was one of main reasons of slag sticking onto the snorkel. All the three kinds of additives employed in this study could decrease the viscosity of ladle slag remarkably. At 1500℃, the viscosity of ladle slag without additives is 6 Pa×s. By adding 10%(w) CaO+CaF2, the viscosity was decreased lower than 3 Pa×s. Whereas by adding 10%(w) CaO+B2O3 or 4%(w) Li2O, the viscosity was lower than 2 Pa×s.