A steel charge and slag forming material is heated in a ladle to form molten steel covered by a slag containing silicon, manganese and calcium oxides. The steel is stirred by injection of an inert gas such as argon or nitrogen to cause silicon/manganese deoxidalion and desulphurization to produce a silicon/manganese killed molten steel. Stirring of the molten steel by the inert gas injection while in contact with slag high in calcium oxide generates low free oxygen levels in the steel and desulphurization to sulphur levels below 0.009%. The slag may be subsequently thickened due to lime addition to prevent return of sulphur back into the steel and oxygen may be injected into the steel to increase its free oxygen content in the steel having castability, which provides a possibility of use thereof in twin roller casting machine.
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