Effect of Additives on Viscosity of LATS Refining Ladle Slag

Abstract

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°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°C could be decreased lower than 2 Pa·s.