Proper control of the path of slag formation in BOF steel-making is peremptory to achieve improved lining life and other performance indices. The formation of initial basic slag is extremely difficult owing to constraints of input materials chemistry. Technology has been developed to achieve a basicity of 2.5 at 15-20% blow and to contain FeO of the final slag. The effect of super saturation of slag by MO in both the halves of the blow, reduces the lining erosion.

Formation of initial siliceous slag and low basicity slag adversely affect the lining life. The deleterious effects of FeO and temperature are also due to increased fluidity and its adverse effect on slag coating.

With an aim to attain the MgO level in the slag of 9-12% in both the halves of the blow separately, addition of SLAG CONDITIONER to the tune of 20-30 Kg/tls in first half and 10-20 Kg/tls in the second half is recommended.

The slag attack in the first half of the blow can be effectively controlled if it is supersaturated with MgO. This would prevent the dissolution of MgO from lining. MgO solubility in slag increases at low 'FeO & basicity' levels and is insensitive to temperature. MgO saturation is strongly dependent on Si content of the hot metal. Higher Si increases the MgO solubility in slag.

The phenomenal improvement in lining life by 50% over the base value is possible by super saturation of slag with MgO in both the halves of the blow, coupled with FeO control. The super saturation raises the viscosity of slag and makes it temperature dependent. This also results in imparting adhesive protective coating on the lining.