Sumitomo Metal Industries, Inc.

Takami Ikeda

Tohru Matsuo

Kantaro Sasaki

Takashi Okazaki

Takashi Fukui

A process for dephosphorizing molten pig iron by adding (a) lime, converter slag and/or iron oxide, (b) iron oxide and/or oxidizing gas, and if necessary (c) flourspar and/or soda ash to the molten pig iron stored in a treating vessel in order to adjust the amount of % CaO to correspond to 0.3 to 3.0 times the sum of the amounts of % SiO.sub.2 and % P.sub.2 O.sub.5 and to adjust the amount of total iron to 15 to 50%, in the slag composition after treatment, thereby obtaining a high dephosphorization.

Process for dephosphorizing molten pig iron

A process for the vacuum decarburization wherein oxygen gas is blown downward upon the molten steel surface under reduced pressure from a height apart from said steel surface characterized by applying a Laval nozzle having a divergence calculated from the theoretical Mach number which is, in turn, determined by a definite equation as a lance to provide a desired dynamic pressure on said molten steel surface and a desired depth of impression formed in the molten steel. In this process, a cooling medium for cooling the lance with a cooling medium sprayed with water.

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Amagasaki, Japan

Takami Ikeda