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公开(公告)号：US20240263261A1
公开(公告)日：2024-08-08
申请号：US18565348
申请日：2022-05-12
发明人： Hidemitsu NEGISHI , Rei YAMADA , Chikashi TADA
摘要： A method wherein a denitrification treatment allows an extremely low nitrogen concentration range to be stably and quickly reached, so denitrification and/or desulfurization of molten steel can be efficiently performed. Wherein CaO-and-Al2O3-containing slag is formed on top of molten steel charged in a vessel and an oxygen-containing gas is blown from above, while the slag and the molten steel are brought into contact with each other to remove nitrogen in the molten steel. An Al concentration in the steel is kept at or higher than a value determined by Formula (1) according to a stirring power density, and the gas is blown so a ratio between a thickness Ls0 of the slag and a depth Ls of a depression in the slag resulting from blowing of the gas meets Ls/Ls0≥1:
Al concentration (mass %) in molten steel=−0.072×ln(stirring power density (W/t))+0.5822 (1)-
公开(公告)号：US20230313330A1
公开(公告)日：2023-10-05
申请号：US18022802
申请日：2021-08-23
发明人： Nobuhiko ODA , Masanori TANNO , Rei YAMADA
CPC分类号： C21C7/064 , C21C5/54 , C21C2300/08
摘要： A method for efficiently manufacturing low-phosphorus molten steel by use of a steelmaking electric furnace, in which slag resulting from melting a solid iron source is effectively separated from molten steel, and thus a unit consumption of lime required to reduce a phosphorus content in the molten steel is reduced. The method includes: charging a solid iron source and an optional molten iron source and melting and heating these raw materials by using electric energy; partly or entirely removing slag generated during the melting; performing dephosphorization by adding dephosphorization flux; and tapping low-phosphorus molten steel thus refined, and in the method, a slag composition ratio being [CaO]/([SiO2]+[Al2O3]) of the slag to be removed is adjusted to be not less than 0.25 and not more than 0.70.
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公开(公告)号：US20240247329A1
公开(公告)日：2024-07-25
申请号：US18560737
申请日：2022-05-12
发明人： Hidemitsu NEGISHI , Rei YAMADA
IPC分类号： C21C7/04
CPC分类号： C21C7/04 , C21C2300/08
摘要： A method by which an extremely low nitrogen concentration range can be stably reached in a short time without use of a top-blown gas is proposed. A molten steel denitrification method is a denitrification process in which CaO-and-Al2O3-containing slag formed by a combination of an Al addition step of adding a metal-Al-containing substance to molten steel to deoxidize and turn the molten steel into Al-containing molten steel and a CaO addition step of adding a CaO-containing substance to the molten steel is brought into contact with the Al-containing molten steel to remove nitrogen in the molten steel, in which the molten steel is stirred at a stirring power density ε of 60 W/t or higher. It is preferable that, in the denitrification process, a surface of the molten steel or the slag is subjected to an atmosphere of 1.0×105 Pa or lower. In a steel production method, the obtained molten steel is cast after the components are adjusted.
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公开(公告)号：US20220372591A1
公开(公告)日：2022-11-24
申请号：US17619998
申请日：2020-05-01
发明人： Rei YAMADA , Kenji NAKASE , Yoshie NAKAI , Naoki KIKUCHI
IPC分类号： C22B1/11
摘要： A method removes phosphorus from a phosphorus-containing substance. In the method, the phosphorus-containing substance that is used as a raw material for metal smelting or refining is reacted with a nitrogen-containing gas so that phosphorus in the phosphorus-containing substance is removed through nitriding. Prior to a treatment of a nitriding removal of phosphorus from the phosphorus-containing substance, a treatment is performed in which the phosphorus-containing substance is heated to an unmolten state temperature range so as to react with a reducing agent, thereby reducing at least a part of metal oxide in the phosphorus-containing substance.
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公开(公告)号：US20240271235A1
公开(公告)日：2024-08-15
申请号：US18567848
申请日：2022-05-12
发明人： Hidemitsu NEGISHI , Rei YAMADA
CPC分类号： C21C7/072 , C21C7/0006 , C21C7/06
摘要： A molten steel denitrification method including CaO-and-Al2O3-containing slag is formed by adding a metal-Al-containing substance to molten steel to deoxidize and turn the molten steel into Al-containing molten steel and adding a CaO-containing substance to the molten steel, and then an oxygen-containing gas is blown from above the slag to perform a denitrification treatment. T·Fe in the slag after the denitrification treatment is set to 3.0 mass % or lower. It is preferable that, in the denitrification treatment, the oxygen-containing gas be supplied such that a ratio Ls/Ls0 between a thickness Ls0 of the slag and a depth Ls of a depression in the slag resulting from blowing of the oxygen-containing gas becomes 0.9 or lower. The obtained molten steel is cast after its components are adjusted. The method allows an extremely low nitrogen concentration range to be stably reached in a short time.
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公开(公告)号：US20230142051A1
公开(公告)日：2023-05-11
申请号：US17914528
申请日：2021-03-24
发明人： Keisuke MIZOBATA , Akifumi HARADA , Yoshie NAKAI , Rei YAMADA
CPC分类号： C21C7/068 , C21C7/10 , C21C7/0068 , C21C2300/06 , C21C7/0075
摘要： A decarburization refining method for molten steel under reduced pressure. The method includes an oxygen-blowing decarburization and a rimmed decarburization. Using operation data taken at a time when oxygen-blowing decarburization is started and a time when oxygen-blowing decarburization is ended, an amount of carbon removed while the oxygen-blowing decarburization is performed is estimated. Based on the estimated amount of carbon removed, a carbon concentration in molten steel at a time when the rimmed decarburization is started is estimated. Using the estimated value as the carbon concentration in molten steel at the time when the rimmed decarburization is started, a change over time in the carbon concentration in molten steel while the rimmed decarburization is performed is calculated. Based on the calculated change over time in the carbon concentration in molten steel while the rimmed decarburization is performed, a determination is made about a time when the rimmed decarburization is ended.
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