Kawasaki Steel Corporation

Kawasaki Steel Company

Nobuo Harada

Tetsuya Fujii

Toshikazu Sakuraya

Hideo Nakamura

Shuji Takeuchi

Yoshiei Kato

Yasuhiro Habu

Toshihiko Emi

A process for producing an extremely low carbon steel in a top- and bottom-blown converter. The process is characterized in top-blowing a mixed gas of oxygen gas and an inert gas onto a molten steel in the top- and bottom-blown converter. The mixed gas is blown through a top-blowing lance at the final decarburization stage, while a gas (selected from a group consisting of an inert gas, oxygen gas and a mixture of oxygen and an inert gas) is bottom-blown into the molten steel in the converter.

Steelmaking of an extremely low carbon steel in a converter

Wear of tuyeres for refining a molten iron is prevented by blowing a CO-containing gas having the defined flow amount, oxygen gas flow amount and CO gas concentration as a shrouding gas which surrounds a core refining gas flow containing oxygen gas through tuyeres of concentric pipes. As the shrouding gas for cooling and protecting the tuyeres, use may be made of an exhaust gas discharged and recovered from a converter or a blast furnace by controlling the concentrations of CO and N.sub.2 in the exhaust gas to the specific limitations.

Method for protecting tuyeres for refining a molten iron

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Chiba, Japan

Nobuo Harada