Effect of additives on viscosity of LATS refining ladle slag

To reduce or eliminate slag sticking onto the ladle immersion cover during the refining process of Ladle Alloying Treatment Station (LATS), the variation of the ladle slag viscosity before and after LATS refining process was investigated. The additives including CaO-CaF2 (CaO/CaF2 mass ratio is 1 : 1), CaO-B2O3 (CaO/B2O3 mass ratio is 1 : 1) and Li2O were employed to decrease the viscosity of LATS refining ladle slag. The mechanism of additives decreasing slag viscosity was analyzed. The rotary cylinder method was adopted in the viscosity measurements. The results showed that the viscosity of LATS refining ladle slag was very high and could be further increased after LATS refining process, which was one of main reasons for slag sticking onto immersion cover. All the three kinds of additives employed in this research could decrease the viscosity of LATS refining ladle slag remarkably. At 1 500 degrees C, the viscosity of ladle slag without any additives is about 6.5 Pa.s. But by adding 10 mass% CaO-CaF2 or 10 mass% CaO-B2O3 or 4 mass% Li2O, the slag viscosity at 1 500 degrees C could be decreased lower than 2 Pa.s.