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公开(公告)号：US20240287632A1
公开(公告)日：2024-08-29
申请号：US18571637
申请日：2022-06-14
Applicant: JFE STEEL CORPORATION
Inventor： Hidemitsu NEGISHI , Takeshi MURAI , Keisuke MIZOBATA
CPC classification number: C21C5/5229 , C21C7/0006 , C21C7/06 , C21C7/068 , C21C7/10 , C21C2300/08
Abstract: A treatment method of molten steel capable of preventing metal components in molten steel from being reoxidized by reacting with oxides in molten slag, inhibiting occurrence of inclusions, and reducing nitrogen in the molten steel. The treatment method of molten steel in which a potential difference is applied between the molten steel and the molten slag by using a direct-current power supply and through two electrodes which are a negative electrode being an electrode in contact with the molten steel and a positive electrode being another electrode in contact with only the molten slag is characterized by including: a deoxidation step of deoxidizing the molten steel by adding a deoxidizing agent to the molten steel; and a step of applying the potential difference after the deoxidation step. Also, a steel production method by which the obtained molten steel is cast after components thereof are adjusted.
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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
Applicant: JFE STEEL CORPORATION
Inventor： Hidemitsu NEGISHI , Rei YAMADA
IPC: C21C7/04
CPC classification number: C21C7/04 , C21C2300/08
Abstract: 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：US20240076754A1
公开(公告)日：2024-03-07
申请号：US18270617
申请日：2021-12-21
Applicant: JFE STEEL CORPORATION
Inventor： Futoshi OGASAWARA , Hidemitsu NEGISHI , Kenji NAKASE , Shota AMANO , Yumi MURAKAMI , Rei YOKOMORI , Yudai HATTORI , Ryo KAWABATA , Naoki KIKUCHI
Abstract: A molten iron refining method having, an auxiliary material, and an oxidizing gas supplied through a top-blowing lance, to a cold iron source and molten pig iron that are contained/fed in a converter-type vessel, and molten iron is subjected to a refining process. A pre-charged cold iron source is charged into the converter-type vessel at an amount not larger than 0.15 times. A furnace-top-added cold iron source that's part or all of the cold iron source and added from a furnace top is fed during the refining process. A burner at a leading end of the top-blowing lance that spray holes through which a fuel and a combustion-supporting gas are ejected. During the refining process, a powdery auxiliary material processed into powder that's part of the auxiliary material is blown in, to pass through a flame formed by the burner.
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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
Applicant: JFE STEEL CORPORATION
Inventor： Hidemitsu NEGISHI , Rei YAMADA
CPC classification number: C21C7/072 , C21C7/0006 , C21C7/06
Abstract: 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：US20240076756A1
公开(公告)日：2024-03-07
申请号：US18272396
申请日：2021-12-08
Applicant: JFE STEEL CORPORATION
Inventor： Hidemitsu NEGISHI
IPC: C21C7/064
CPC classification number: C21C7/064
Abstract: Proposed is a method for efficiently desulfurizing molten metal in a short time without passing an excessive current when applying a potential difference between slag and metal. Using a direct-current power source, this method for desulfurizing molten metal applies a potential difference between molten slag and molten metal through electrodes, of which one electrode contacting the molten metal serves as a negative electrode and the other electrode contacting only the molten slag serves as a positive electrode. An applied current density Ja is determined according to an equilibrated S concentration [S]e0 before application of a potential difference such that an equilibrated S concentration [S]ea when a potential difference is applied becomes equal to or lower than a target S concentration [S]ft.
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Patent Agency Ranking
公开(公告)号：US20240271234A1
公开(公告)日：2024-08-15
申请号：US18289968
申请日：2022-05-12
Applicant: JFE STEEL CORPORATION
Inventor： Chikashi TADA , Hidemitsu NEGISHI
CPC classification number: C21C7/072 , C21C7/0006 , C21C7/10
Abstract: A method for secondarily refining molten steel s by which a low nitrogen concentration range can be stably reached at high speed without causing operational problems, and a method of producing steel are proposed. In the method for secondarily refining molten steel, CaO-and-Al2O3-containing slag is formed by a combination of an Al addition step of adding a metal-Al-containing substance to molten steel to turn the molten steel into Al-containing molten steel and a CaO addition step of adding a CaO-containing substance to the molten steel, and then an oxygen blowing process including a denitrification process is performed by blowing oxygen-containing gas so as to pierce the slag to reach the Al-containing molten steel, in which an Al concentration [Al]i (mass %) in the molten steel immediately before the oxygen blowing process is equal to or higher than a value [Al]e calculated by Formula (A) based on a stirring power density ϵ (W/t) during formation of the slag, and an Al concentration [Al]f upon completion of the oxygen blowing process is 0.03 mass % or higher. In the method of producing steel, the obtained molten steel is cast after adjusting the composition.
[Al]e=−0.072×In(ϵ)+0.5822 . . . (A)-
公开(公告)号：US20240263261A1
公开(公告)日：2024-08-08
申请号：US18565348
申请日：2022-05-12
Applicant: JFE STEEL CORPORATION
Inventor： Hidemitsu NEGISHI , Rei YAMADA , Chikashi TADA
Abstract: 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)-
8.发明公开公开(公告)号：US20240076755A1
公开(公告)日：2024-03-07
申请号：US18272474
申请日：2021-12-02
Applicant: JFE STEEL CORPORATION
Inventor： Shota AMANO , Hidemitsu NEGISHI , Yumi MURAKAMI , Futoshi OGASAWARA , Kenji NAKASE
CPC classification number: C21C7/0037 , C21C5/35 , C21C5/4606 , C21C7/068
Abstract: A method that, regarding a process of refining molten iron, can increase the thermal margin and the amount of cold iron source to be used. A burner having jetting holes for jetting a fuel and a combustion supporting gas is provided at a leading end part of one lance that top-blows an oxidizing gas to molten iron contained in a converter-type vessel, or at a leading end part of another separate lance. A powdery auxiliary raw material or an auxiliary raw material processed into a powder form that is blown into the molten iron from the one lance or the other lance passes through a flame formed by the burner. This top-blowing lance for a converter is configured to secure a predetermined heating time and powder-fuel ratio. Also, a method for adding an auxiliary raw material and a method for refining of molten iron that use this top-blowing lance.
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公开(公告)号：US20240068060A1
公开(公告)日：2024-02-29
申请号：US18271612
申请日：2021-12-09
Applicant: JFE STEEL CORPORATION
Inventor： Hidemitsu NEGISHI , Shota AMANO , Yumi MURAKAMI , Futoshi OGASAWARA , Kenji NAKASE
Abstract: Proposed is a molten iron refining method capable of securing an in-flame staying time period of a heat transfer medium without being influenced by height adjustments of a blowing-purpose oxygen-blowing lance. As far as to a position lower than an upper end inside a converter-type vessel 1, a blowing-purpose oxygen-blowing lance 3 that supplies oxidizing gas and is capable of ascending and descending and at least one burner lance 4 capable of ascending and descending independently of the blowing-purpose oxygen-blowing lance are inserted. From the blowing-purpose oxygen-blowing lance, either oxidizing gas or oxidizing gas and CaO-containing refining agent are blown onto the molten iron. Also, a flame is formed by causing the burner lance to discharge fuel gas and combustion supporting gas. Powder particles discharged from the burner lance are caused to pass through the flame and to be blown onto the molten iron in a heat-transferred state, so that the molten iron is thermally compensated.
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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
Applicant: JFE STEEL CORPORATION
Inventor： Keisuke MIZOBATA , Akifumi HARADA , Yoshie NAKAI , Takeshi MURAI , Hidemitsu NEGISHI
IPC: C21C7/10
CPC classification number: C21C7/10
Abstract: 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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