The present invention relates to a process for producing steel in a ladle furnace in which the molten steel is stirred by injection of an inert gas in the lower part of the furnace. According to the invention, the stirring of the bath of steel is effected by the injection of gaseous argon so as to distribute in a homogeneous manner the additives added and the metal temperature in the course of the treatment, while there is simultaneously injected liquid argon above the surface of the bath in the region of intumescence. In this way, substantially any increase in the concentration of nitrogen of the bath of steel in the course of the treatment is avoided. In some cases, and in particular when wires of the type filled with silico-calcium are employed, a reduction in the concentration of nitrogen in the bath of steel is found.

The present invention relates to a molten steel refining method for refining molten steel, the carbon content of which is not more than 0.1 weight %, by blowing oxygen gas for decarburization at a blowing speed so that a cavity, the depth of which is 150 to 400 mm, can be formed on the surface of molten steel in a straight barrel type vacuum refining apparatus in which a straight barrel type vacuum vessel having no vessel bottom and a ladle are arranged. When necessary, the above decarburizing processing conducted by blowing oxygen gas is combined with: an Al heating process in which Al added into the vacuum vessel is burned by oxygen gas blown into the vacuum vessel at a blowing speed such that the cavity depth can be 50 to 400 mm; a degassing treatment conducted in a high vacuum condition; a desulfurizing treatment in which a desulfurizing agent is blown into the vacuum vessel; or a burner heating treatment in which a combustion improving agent is blown together with oxygen gas, wherein each treatment except for the high vacuum degassing treatment is conducted in a degree of vacuum of 100 to 400 Torr.

The invention encompasses a pneumatic steelmaking vessle and a method for the production of steel from hot carbon-bearing metallized raw materials such as direct reduced iron. The vessle is a refractory-lined ladle, having an eccentric ladle cover with an opening on one side. Opposite the opening in the ladle cover is at least one downwardly directed oxygen lance or tuyere. The vessel is mounted on trunnions for rotation about its central axis to a generally horizontal position. The bottom of the vessel has a porous plug, and a hot metal outlet controlled by a sliding gate closure member or other convenient type closure. The vessel is used in connection with a method of steelmaking by serving as the means for transporting molten metal to melting, refining, ladle metallurgy, and teeming operations.

A process of production of high cleanness extra low carbon steel includes steps of producing low carbon rimmed steel by means of a refining furnace, supplying a deoxidization agent to a slag in a laddle for adjusting iron concentration in slag at lower than or equal to 5%, subsequently performing vacuum degassing process with blowing oxygen to lower carbon content in the steel lower than or equal to 0.006%.

A method of producing carbon steel and low-alloy steel in a basic oxygen furnace is disclosed, in which a blow of the bottom-blowing gas predominantly comprised of carbon dioxide is introduced into a molten metal through at least one nozzle provided in the bottom or side wall of said basic oxygen furnace at least partly during the period of time from the beginning of blowing to the tapping of the melt, and the flow rate of the bottom-blowing gas is 1/200 - 9/100 the rate of oxygen impinged upon the melt through a lance.