MOLTEN STEEL DENITRIFICATION METHOD AND STEEL PRODUCTION METHOD

WIPO Patent Application WO/2022/259805

A1

The present invention proposes a method whereby it is possible to reach an extremely low nitrogen concentration range stably within a short period of time. Provided is a molten steel denitrification method in which denitrification treatment is carried out by forming slag that contains CaO and Al2O3 by combining an Al addition step for adding a metal Al-containing substance to molten steel to deoxidize the molten steel and obtain Al-containing molten steel and a CaO addition step for adding a CaO-containing substance to the molten steel, and then spraying an oxygen-containing gas onto the slag. The T.Fe in the slag after the denitrification treatment is set to 3.0 mass% or less. In the denitrification treatment, it is preferred that, when supplying the oxygen-containing gas, the ratio LS/LS0 of the depth LS of a depression in the slag that is formed as the result of the spraying of the oxygen-containing gas to the thickness LS0 of the slag is 0.9 or less. Also provided is a steel production method in which the contents in the molten steel thus produced are adjusted and then the molten steel is cast.

NEGISHI HIDEMITSU (JP)
YAMADA REI (JP)

PCT/JP2022/020007

December 15, 2022

May 12, 2022

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JFE STEEL CORP (JP)

C21C7/00; C21C7/10

JPH09165615A	1997-06-24
JP2007211298A	2007-08-23
JPH08246024A	1996-09-24
JPS61272313A	1986-12-02
CN108396094A	2018-08-14
JPH0532073A	1993-02-09
JP2007211298A	2007-08-23
JPH08246024A	1996-09-24

UENO ET AL., IRON AND STEEL, vol. 101, 2015, pages 74

GINZA MARONIE P.C. (JP)

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