Nippon Kokan Kabushiki Kaisha

Yasuhiro Matsuda

Yoshimi Komatsu

Tsuneo Kondo

Teruyuki Hasegawa

Masayuki Hanmyo

Hirohisa Nakashima

Yoshiharu Miyawaki

Ryuji Yamaguchi

Seigo Kuwano

Yusuke Shiratani

Kazuhiko Matsuo

Yusuke Shirotani

Yoneichi Hamada

Akio Shiwata

Tsutomu Usui

The gap between an insertion hole formed in a covering of a ladle and an electrode inserted through the insertion hole is sealed by sealing means. The sealing means has a cap seal longitudinally and slidably fitted over the electrode. A base seal is hermetically disposed between the cap seal and the covering in such a manner that a gap is provided between the electrode and the base seal. The base seal has a gas injection nozzle intended to discharge a gas toward the electrode and another gas injection nozzle intended to discharge the gas downwardly. The use of the base and cap seals enables securing the sealing functions thereof despite any movement of the electrode, thus preventing the pickup of [N] as well as the reoxidation of molten steel. When a gas seal is effected by the formation of a flow of gas rotating around the electrode about the axis thereof, the sealing performance can be more enhanced. Further, when the base seal is cooled by causing cooling water to be circulated therethrough, its durability can also be enhanced.

Arc-heating type extra-furnace refining apparatus

A process for desulfurizing molten steel comprising the steps of: removing converter slag from molten steel; adding a desulfurizing flux onto the molten steel from which the converter slag has been removed; supplying power to electrodes at a predetermined distance from the molten steel so as to generate an electric arc, the desulfurizing flux being melted by arc-heating so as to form the slag; and introducing a gas into the molten steel through a lance submerged into the molten steel to stir the molten steel and the slag which are arc-heated. In the process the desulfurizing flux is melted to a slag consisting essentially of 53 to 62% of CaO, 0 to 15% of SiO.sub.2, and 30 to 45% of Al.sub.2 O.sub.3.

Process for desulfurizing molten steel

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Hiroshima, Japan

Yasuhiro Matsuda