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51. 发明专利

JP2002068789A METHOD FOR TREATMENT OF STEEL-MAKING SLAG 审中-公开
公开(公告)号：JP2002068789A
公开(公告)日：2002-03-08
申请号：JP2001211017
申请日：2001-07-11
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , MORISHIGE HIROAKI , IGARASHI MASAO , MATSUNAMI TADANORI
IPC分类号： C04B5/06 , C21C5/36 , C21C7/00
摘要： PROBLEM TO BE SOLVED: To insolubilize Pb in a Pb-containing slag generated in a steel making process and to make the slag hardly hydrating-expandable. SOLUTION: A slag that is generated in a steel making process and contains >=0.001 mass% Pb is removed from the bath surface of molten steel and subjected to a heat treatment to be melted. Thereafter, its slag basicity [(T. CaO)/(SiO2)] is adjusted to

52. 发明专利

JP2001194074A SLAG CONTAINING INSOLUBLE Pb AND SLAG TREATMENT METHOD FOR INSOLUBILIZING Pb 失效
公开(公告)号：JP2001194074A
公开(公告)日：2001-07-17
申请号：JP2000000866
申请日：2000-01-06
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , MORISHIGE HIROAKI , MATSUNAMI TADANORI
IPC分类号： C21C5/36 , F27D15/00
摘要： PROBLEM TO BE SOLVED: To insolubilize Pb contained in slag that is generated in a Pb- containing steel-making process. SOLUTION: The composition of slag containing at least 0.001 mass % of Pb is adjusted to satisfy an expression (1), (T.CaO)/(SiO2)

53. 发明专利

JP2001192721A SLAG GENERATED IN STEEL MAKING STAGE AND TREATING METHOD FOR SLAG 失效
公开(公告)号：JP2001192721A
公开(公告)日：2001-07-17
申请号：JP2000003541
申请日：2000-01-12
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , MORISHIGE HIROAKI , IGARASHI MASAO , MATSUNAMI TADANORI
IPC分类号： C21C5/38 , C21C7/00
摘要： PROBLEM TO BE SOLVED: To make Pb in Pb-containing slag generated in a steel making stage insoluble and also hard to be expanded by hydration. SOLUTION: Slag generated in a steel making stage and containing Pb of 0.001 mass % or more is regulated in such a manner that the basicity of the slag [(T.CaO)/(SiO2)] is controlled to 1.5 or less, and also, the concentration of (MgO) is controlled to 12 mass % or less and is thereafter separated or removed from a bath surface of the molten steel, where (T.CaO) denotes the concentration (mass %) obtained by converting the whole (Ca) contained in the slag into (CaO), (SiO2) denotes the concentration (mass %) of (SiO2) in the slag, and (MgO) denotes the concentration (mass %) of (MgO) in the slag. Since, as for the slag in this invention, the coefficient of vapor expansion satisfies 1.5% or less, and also, the amount of Pb to be eluted from the slag satisfies the environmental standard value, the slag can be utilized as resources.

54. 发明专利

JP2001181729A SLAG IN CHROMIUM-CONTAINING STEEL AND TREATING METHOD THEREFOR 失效
公开(公告)号：JP2001181729A
公开(公告)日：2001-07-03
申请号：JP36529799
申请日：1999-12-22
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , MORISHIGE HIROAKI , MATSUNAMI TADANORI
IPC分类号： C21C5/36 , C21C7/00 , C21C7/064
摘要： PROBLEM TO BE SOLVED: To prevent an elution of hexavalent Cr from a removed slag in a melting and refining process of a chromium-containing steel. SOLUTION: A desulfurizing partition ratio (S)/[S] between the molten steel and the slag, is adjusted so as to satisfy the formula, log(S)/[S]>=0.08[-614/T +0.531[C]+0,413[Si]+0.616(T.CaO)/(SiO2)-0.047(Al2 O3)+0.0176(MgO)+0.0264(CaF2)+0.172] (wherein, T is the molten steel temperature ( deg.C); [C] is C concentration in the molten steel (concentration is mass %, the same shall apply hereinafter); [Si] is Si concentration in the molten steel; (T.CaO) is the conversion concentration of Ca in (CaO) and Ca in (CaF2) in the slag into CaO; (SiO2) is SiO2 concentration in the slag; (Al2O3) is Al2O3 concentration in the slag; (MgO) is MgO concentration in the slag; and (CaF2) is CaF2 concentration in the slag). Further, for promoting the desulfurization, the melting and refining time is lengthened or the deoxidizer such as Si, Al, is added.

55. 发明专利

JPH1150127A REFINING OF LOW SILICON STAINLESS STEEL 失效
公开(公告)号：JPH1150127A
公开(公告)日：1999-02-23
申请号：JP21545597
申请日：1997-07-28
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , MAKINO NOBUYUKI , MORISHIGE HIROAKI , HATA KOKI
IPC分类号： C21C7/00
摘要： PROBLEM TO BE SOLVED: To execute a stable casting and to reduce the developing rate of defect caused by inclusion in a product production process and the product by controlling the composition and the quantity of the inclusion in a steel, in the production process of a low Si stainless steel containing

56. 发明专利

JPH10152718A METHOD FOR MELTING CHROMIUM-CONTAINING STEEL 失效
公开(公告)号：JPH10152718A
公开(公告)日：1998-06-09
申请号：JP32800396
申请日：1996-11-25
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , KANEKAWA MASARU , TAKANO HIRONORI
IPC分类号： C21C5/52
摘要： PROBLEM TO BE SOLVED: To shorten molten time, to reduce the unit requirement of electric power and to drastically improve productivity and cost by blowing a special quantity of mixed gas of the air and the oxygen having a specific oxygen ratio per ton of molten steel into the molten steel. SOLUTION: The air or the mixed gas is blown into the molten steel 3 from a bottom-blown nozzle 6 arranged at the bottom part of an electric furnace 1 or from a lance inserted from a furnace belly part into the furnace. In the case of melting a chromium-containing steel by this method, into the molten steel at the time of melting unmelting raw material 4 charged in the electric furnace 1 at >=80vol%, the air or the mixed gas of the air and the oxygen having 21-50vol% oxygen ratio is blown at 0.3Nm /min.ton of the molten steel. Then, [Si] concn. in the raw material and the oxygen ratio in the mixed gas are adjusted according to a target [Si] concn. in the molten steel. By this method, the hitting of the target [Si] concn. after melting can easily be obtd. by adjusting gas blowing condition, etc.

57. 发明专利

JPH09310113A REFINING METHOD FOR HIGHLY CLEAN STAINLESS STEEL 失效
公开(公告)号：JPH09310113A
公开(公告)日：1997-12-02
申请号：JP14855096
申请日：1996-05-21
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , MIYAZAKI MASAFUMI , TAKANO HIRONORI , IWASAKI HIROSHI , KAWAI HIROYUKI , MATSUNAMI TADANORI
IPC分类号： C21C7/00 , C21C7/04 , C21C7/06 , C21C7/072
摘要： PROBLEM TO BE SOLVED: To make inclusions innoxious by inhibiting the formation of hard, high m.p. inclusions and improving the ductility of inclusions at the time of hot working, in a stainless steel refining method. SOLUTION: At the time of refining stainless steel, Al is used as a reducing agent for the slag containing chromium oxide formed at oxidizing refining, and Ca or Ca alloy or both of them are added to molten steel in a ladle after tapping. At this time, the additive quantity of Ca, as pure Ca content, is regulated to >=50g per ton of molten steel, and, after Ca addition, inert gas to the amount satisfying inequality Qd >=Wca /4.2 is blown into the molten steel to perform agitation of the molten steel. In the inequality, Qd represents the flow rate (Nm ) of the blown inert gas and Wca represents the sum (kg) of pure Ca content in the added Ca or Ca alloy.

58. 发明专利

JPH08302417A METHOD FOR MELTING CHROMIUM STEEL 失效
公开(公告)号：JPH08302417A
公开(公告)日：1996-11-19
申请号：JP12881895
申请日：1995-05-01
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , TAKANO HIRONORI , YAMAMOTO TETSUYA
IPC分类号： C21C5/52
摘要： PURPOSE: To realize the efficient melting by reducing the oxidation of [Cr] in the molten steel in the process to melt Cr steel in an electric furnace. CONSTITUTION: The mixed gas containing >=10% oxygen gas is blown into the molten steel by >=0.1Nm /min per unit ton of the molten steel after >=20% of the material charged in an electric furnace is melted to become the molten steel. As the temperature of the molten steel rises, the ratio of the oxygen gas in the mixed gas is increased up to 90%. The decarburizing reaction by the oxygen in the mixed gas procedes under the condition where the oxidation of [Cr] in the molten steel is small, and the power consumption unit for melting is reduced by the decarburizing reaction heat, and the melting time is reduced.

59. 发明专利

JPH0885813A METHOD FOR EFFECTIVELY REFINING MOLTEN CHROMIUM-CONTAINING STEEL USING DECARBURIZED SLAG 失效
公开(公告)号：JPH0885813A
公开(公告)日：1996-04-02
申请号：JP22222894
申请日：1994-09-16
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , TANAKA SHIGENORI , OKIMORI MAYUMI , IWASAKI HIROSHI , MORISHIGE HIROAKI
IPC分类号： C21C7/00 , C21C5/28 , C21C7/068
摘要： PURPOSE: To reduce and recover produced chromium oxide in a method at a low cost in a decarburization-refining of molten chromium-containing steel and also, to effectively execute the reduction and the decarburization. CONSTITUTION: At the time of tapping the decarburization-refined molten steel in the decarburization-refining of the molten chromium-containing steel, the crude molten steel having >=1400 deg.C, >=0.2mass% [Si] concn. and >=1.2mass% [C] concn., is received under the condition of remaining slag containing 15-50mass% chromium oxide produced by the decarburization-refining in a furnace. The chromium oxide is reduced with [Si] and [C] in the crude molten steel. By this method, since the remarkable lowerings of the unit consumptions of Si for reduction and dilute gas, and the shortening of the refining time are obtd., the refining cost can remarkably be reduced.

60. 发明专利

JPH0885810A METHOD FOR REFINING MOLTEN CHROMIUM-CONTAINING STEEL 失效
公开(公告)号：JPH0885810A
公开(公告)日：1996-04-02
申请号：JP22538094
申请日：1994-09-20
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , TANAKA SHIGENORI , OKIMORI MAYUMI , IWASAKI HIROSHI , MORISHIGE HIROAKI
IPC分类号： C21C7/00 , C21C7/068 , C21C7/10
摘要： PURPOSE: To easily control [N] concn. while using inexpensive N2 gas by using the same refining vessel after executing decarburizing treatment to molten chromium-containing steel under the atmospheric pressure, blowing N2 gas of a specific quantity and executing reduction treatment under a specific vacuum degree. CONSTITUTION: After executing the decarburizing treatment to the molten chromium-containing steel under the atmospheric pressure by using the same refining vessel, the decarburizing and reduction treatment or only the reduction treatment is executed under the vacuum. At this time, the N2 gas or the N2 +Ar gas as blowing gas in the reduction treatment is blown at >=0.2Nm /min.ton of molten steel. At the same time, the reduction treatment is executed for at least one min in the vacuum degree satisfying the equation a=-1.35- 3280/(T+273)-0.75} (0.01[Ni]-0.045[Cr]+0.009), P ×10 )+10 or P ×10 )× (QAr +QN2 )/QAr }+10 matching to [N] concn. Wherein, T is molten steel temp. ( deg.C), [Ni] and [Cr] are Ni and Cr (concn.%) in the molten steel, P is the vacuum degree (Torr), and QAr and QN2 are Ar and N2 gas blowing quantity, respectively (Nm /min).

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