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公开(公告)号：US20190048431A1
公开(公告)日：2019-02-14
申请号：US16079712
申请日：2017-02-15
发明人： Yusuke FUJII , Yoshie NAKAI , Naoki KIKUCHI , Naoya SHIBUTA , Shinichi NAGAI , Takahiko MAEDA , Yuji MIKI
摘要： A molten steel refining method includes throwing a powder to molten steel while heating the powder with a flame formed by combustion of a hydrocarbon gas at the leading end of a top blowing lance. The lance height of the top blowing lance (the distance between the static bath surface of the molten steel and the leading end of the lance) is controlled to 1.0 to 7.0 m, and the dynamic pressure P of a jet flow ejected from the top blowing lance calculated from equation (1) below is controlled to 20.0 kPa or more and 100.0 kPa or less. P=ρg× U2/2 . . . (1) wherein P is the dynamic pressure (kPa) of the jet flow at an exit of the top blowing lance, ρg the density (kg/Nm3) of the jet flow, and U the velocity (m/sec) of the jet flow at the exit of the top blowing lance.
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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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公开(公告)号：US20240294998A1
公开(公告)日：2024-09-05
申请号：US18570832
申请日：2022-05-26
发明人： Akifumi HARADA , Yoshie NAKAI
摘要： A molten steel refining method. The method includes refining molten steel contained in a ladle by using an RH vacuum degasser. In the refining step, the surface of the molten steel circulating in a vacuum vessel of the RH vacuum degasser is subjected to a plasma treatment in which the surface of the molten steel is exposed to a hydrogen gas or an inert gas containing a hydrogen gas in the form of plasma gas under the conditions that satisfy a specified formula to reduce the amount of at least one element selected from oxygen, nitrogen, and sulfur, contained in the molten steel.
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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：US20240287633A1
公开(公告)日：2024-08-29
申请号：US18570789
申请日：2022-05-26
发明人： Akifumi HARADA , Yoshie NAKAI
IPC分类号： C21C7/072
CPC分类号： C21C7/072
摘要： A molten steel refining method. The method includes performing a gas stirring process for stirring molten steel in a ladle by blowing a stirring gas into the molten steel contained in the ladle. In the gas stirring process, a surface of the molten steel, which is in a flow state due to the gas stirring process, in the ladle is subjected to a plasma treatment in which the surface of the molten steel is exposed to a hydrogen gas or an inert gas containing a hydrogen gas in the form of plasma gas from plasma generators above the molten steel in the ladle under conditions that satisfy a specified formula, and the plasma treatment reduces an amount of at least one element selected from oxygen, nitrogen, and sulfur, contained in the molten steel.
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公开(公告)号：US20230340629A1
公开(公告)日：2023-10-26
申请号：US18010103
申请日：2021-06-16
IPC分类号： C21C7/10
CPC分类号： C21C7/10
摘要： A molten steel refining method increases a circulating rate using an RH vacuum degassing apparatus. An immersion depth of an immersion tube into molten steel inside a vacuum tank or a circulating gas flow rate is determined such that a stirring power energy density ε for the molten steel meets the following formulae: ε = [371GT × ln{ 1 + (ρLgH0/P)}]/Wv, Wv = (π·Dv2/4) × H0 × ρL/1000, H0 = hv + L - hG, hv = (P0 - P)/(ρLg) + 1 -L, 1.35 × 105 × DU/WV
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公开(公告)号：US20230083264A1
公开(公告)日：2023-03-16
申请号：US17797909
申请日：2021-02-02
发明人： Shuji KUYAMA , Tomoyoshi OGASAHARA , Yoshie NAKAI , Keisuke MIZOBATA , Tomoharu ISHIDA , Masamichi KIKUCHI
IPC分类号： C21C7/068 , G01N33/2025 , F27D7/06 , C21C7/10 , C21C7/072
摘要： A decarburization end point determination method includes: estimating the carbon concentration and oxygen concentration of the molten steel and carbon dioxide gas concentration of exhaust gas in the vacuum chamber by using measurement values of the carbon concentration and the oxygen concentration of the molten steel, a measurement value of internal pressure of the vacuum chamber, and a model formula; correcting a parameter included in the model formula to reduce at least one of a difference between an estimate value and a measurement value of the oxygen concentration and a difference between an estimate value and a measurement value of the carbon dioxide gas concentration of the exhaust gas; estimating the carbon concentration of the molten steel by using the model formula in which the parameter is corrected; and determining timing when an estimate value reaches a target value as the completion time point of the vacuum decarburization treatment.
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