Effect of Al2O3 content on metallurgical characteristics of refining slag

摘要

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 log (a(MgO)/a(Al2O3)) of the slag increase; the measured total oxygen content decreases, inclusion number and area decrease, and the average content ratio, X-MgO/X-Al2O3 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.