Nippon Steel Corporation

Yasuo Obana

Koichi Endoh

Hideyuki Takahama

Masataka Yoshii

Takuo Kono

Tatsuro Kuwabara

Hideo Yaoi

Fumio Hayashi

Shigenori Yagura

Mitsugu Anabuki

Toshiyuki Kaneko

Toshihiko Kaku

Seiji Aso

Makoto Moriguchi

Production method for low carbon molten steel using vacuum degassing and

A treating agent of molten steel according to the present invention is used for desulfurization molten steel for desulfurizing it in a reaction vessel which is lined with a basic refractory containing MgO, and consists of CaO, CaF.sub.2 and MgO and unavoidable impurities contains from 10 to 60% by weight of MgO, and has a weight ratio of {(% CaF.sub.2)/((% CaO)+(% CaF.sub.2))}.times.100(%) of from 20 to 80%. Said agent is injected with the aid of inert carrier gas into the molten steel and floats toward a portion of the molten steel bath essentially free of slag. Another treating agent essentially consisting of CaO and CaF.sub.2 may be also injected prior and/or subsequent to injection of said agent, so as to decrease inclusions. The inert gas may also be injected after injection of said agent(s).

Treating agent for desulfurizing molten steels and method for treating

Refining of molten pig iron and steel in a converter by oxygen blowing continuously at least four charges in a converter to a carbon content in a range from 0.09 to 0.15% and further subjecting the molten steel to a secondary refining by addition or removal of carbon.

Process for refining molten pig iron and steel

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Oita, Japan

Yasuo Obana