Effect of Al 2 O 3 content on metallurgical characteristics of refining slag

Abstract

The metallurgical effects of Al₂O₃ in CaO–Al₂O₃–SiO₂–MgO system slag on the desulfurisation ability, inclusions and steel cleanliness were investigated using thermodynamic calculations, laboratory experiments and industrial tests. The results indicate that: with a decreasing Al₂O₃ content in top slag and with the slag basicity remaining constant, the calculated a _CaO (activity of CaO), C _s (sulphide capacity) and of the slag increase; the measured total oxygen content decreases, inclusion number and area decrease, and the average content ratio, of inclusions increases. Compared with the steel refined using conventional desulfurisation slag N2 (B (basicity): 7.0, Al₂O₃:30%), the steel refined using slag N1 (B: 4.5, Al₂O₃:20%) gives a lower sulphur content, and the inclusions contain more MgO and less Al₂O₃ and contain a certain amount of SiO₂. The Al₂O₃ content has a great effect on the metallurgical characteristics of the refining slag.