a method of treating ferrous metal in a metallurgical vessel having a plurality of two - pipe tuyeres extending generally upwardly through the vessel bottom and in spaced apart relation relative to each other . a flux , such as line , is first blown into the ferrous metal charge through the center tuyere pipe along with the process gas and a second gas is delivered to the outer tuyere pipe . after fluxing , a first process gas consisting principally of oxygen is blown into the charge through the center tuyere pipe along with a sheath of hydrocarbon shielding fluid delivered through the outer tuyere pipe . after a significant portion of carbon oxidation has proceeded to the point where excess oxygen would tend to oxidize chromium or iron , argon is mixed with the oxygen in the center tuyere pipe to the point where it equals or exceeds the proportion of oxygen while the delivery of hydrocarbon shielding fluid is continued through the outer tuyere pipe .