Nippon Steel Corporation

Masataka Yoshii

Satomi Yamamoto

Yasuo Obana

Takuo Kono

Tatsuro Kuwabara

Teruo Matsuo

Teruo Yokoozi

Mitsugu Anabuki

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

A molten iron is continuously refined in a refining vessel of a closed type using a flux composed chiefly of an alkali metal compound so as to decrease the content of P and S to a low level. The alkali metal compound is recovered from the evaporating material and slag generated in the refining and is again used in the refining, while such valuable elements as P, V, etc. may be recovered. The molten iron thus refined can be converted into a steel of high quality in a known oxygen steel making furnace substantially by means of decarburization only and without the use of any flux or with a slight amount thereof. The practice of this invention makes it possible to substantially obviate a substance to be discarded or rejected in the steel making process.

Method for continuous refining of a molten iron base metal

A method for refining a molten steel in vacuum, which comprises blowing a non-oxidizing gas or a non-oxidizing gas together with an oxidizing gas into a bath of the molten steel in a refining vessel of a R-H vacuum degassing apparatus at a position between the bath surface and a bath depth of 50 cm (inclusive) from the bath surface in an almost horizontal direction.

Method for refining a molten steel in vacuum

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Kitakyushu, Japan

Masataka Yoshii