US3700429A - Method of controlling vacuum decarburization - Google Patents

Method of controlling vacuum decarburization Download PDF

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Publication number
US3700429A
US3700429A US751A US3700429DA US3700429A US 3700429 A US3700429 A US 3700429A US 751 A US751 A US 751A US 3700429D A US3700429D A US 3700429DA US 3700429 A US3700429 A US 3700429A
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Prior art keywords
pressure
vessel
decarburization
oxidation
expected
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Expired - Lifetime
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US751A
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Sundaresan Ramachandran
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Allegheny Ludlum Corp
Pittsburgh National Bank
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Allegheny Ludlum Steel Corp
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Assigned to ALLEGHENY LUDLUM CORPORATION reassignment ALLEGHENY LUDLUM CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). 8-4-86 Assignors: ALLEGHENY LUDLUM STEEL CORPORATION
Assigned to PITTSBURGH NATIONAL BANK reassignment PITTSBURGH NATIONAL BANK SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ALLEGHENY LUDLUM CORPORATION
Assigned to PITTSBURGH NATIONAL BANK reassignment PITTSBURGH NATIONAL BANK ASSIGNMENT OF ASSIGNORS INTEREST. RECORDED ON REEL 4855 FRAME 0400 Assignors: PITTSBURGH NATIONAL BANK
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum

Definitions

  • ABSTRACT OF THE DISCLOSURE A method of controlling vacuum decarburization of molten steel wherein the ambient pressure within the vessel within which the decarburization is being performed is monitored and compared with an expected pressure calculated from known decarburization reaction parameters to reflect the effectiveness of the decarburization process and the pressure within the vessel or inputs to the reaction are readjusted in order to establish an efficient decarburization reaction while minimizing the oxidation of desired metallic values within the steel.
  • This invention relates to the process control of molten metal vacuum decarburization systems where the low pressure (subatmospheric) and a mixture of oxidizing and/or inert gases are used to minimize metallic oxidation.
  • vacuum decarburization refers to decarburization systems using subatmospheric pressure.
  • the use of low pressure to promote decarburization of steel and its alloys is well known.
  • U.S. Pat. No. 2,040,566 suggests that alloy steel may be decarburized under vacuum without the oxidation of metallics.
  • vacuum decarburization has not become a commercial process for the decarburization of steels. It is suggested that lack of a responsive method of controlling the reaction has prevented commercial exploitation of the vacuum decarburization process.
  • the basic objective of the invention is to control the oxidation of carbon from the melt during vacuum processes.
  • the reaction is controlled'in a manner such that excessive build up of easily reducible oxides such as iron and chromium does not occur during the decarburization process.
  • oxygen or other oxidizers may be added to a melt at a pressure calculated from thermodynamic considerations. It is also taught that the addition of oxygen or oxidizers is terminated when the pressure within the vessel suddenly increases. This teaching presumes that once the thermodynamic considerations are met, the desired reactions will proceed and no kinetic considerations need be applied.
  • oxidizer Reducing pressure in the system accelerates the decarburization reaction and thus, may reduce the metallic oxidation reactions, thereby reducing the metallic losses.
  • the supply of oxidizer might also be reduced (oxygen), thereby reducing the amount of oxidizer available for the decarburization reaction to a point in which the oxidizer is essentially totally consumed by that reaction, leaving none available for the oxidation of the metallic values sought to be minimized.
  • both the ballast supply and the oxidizer supply may be reduced together to accomplish a combination of the above described effects.
  • ballast load Upon the observation of an actual pressure less than the expected pressure indicating metallic oxidation, I prefer to reduce the ballast load gradually, comparing the difierence between new actual and expected pressures (by computing expected pressured for each new ballast load supplied to the system) until reaching a pressure which the system indicates effective decarburization is occurring. This would be where the system pressure was reduced sufi'iciently to a point Where the actual pressure existing within the vessel equaled or exceeded the expected pressure by calculation of the thermodynamic considerations of the decarburization reaction.
  • Reference numeral 2 indicates a vessel such as a basic oxygen furnace or a processing ladle containing a bath of molten metal 3 and having a sealed covering 4 attached thereto such that a vacuum may be drawn within the vessel.
  • a supply tube 6 is provided for feeding an oxidizer such as oxygen into the vessel and supply tube 8 is provided for feeding a gaseous ballast load such as nitrogen or argon to the interior of the vessel 2.
  • a vacuum pump such as a steam ejector system 10, capable of providing a vacuum to the vessel 2 to support efiicient decarburization of the bath 3 within vessel 2.
  • a double connected steam ejector system having a main line vacuum 12 and a secondary line vacuum line 14 connected to the vessel 2 such as at cover 4.
  • the steam ejector system I employ is a multiple ejector system having a single first stage 16, a double section stage 18 and 18' coupled directly to the first stage 16 and each of which are connected to a steam condenser 20.
  • a ballast supply 22 is provided to first condenser 20.
  • Third stage ejectors 24, 24' and 24" are connected to condenser and directly to ejectors 18 and 18.
  • Third stage ejectors 24 and 25 are individually connected to second stage condensers 26 and 26' which are in turn connected to fourth stage ejectors 28 and 28'.
  • An additional fourth stage ejector 28" is connected directly to the third stage ejector 24. All three of the fourth stage ejectors 28, 28' and 28" are connected to a final stage condenser 30.
  • Ballast is supplied to this system at 22 to assist the establishing of a particular desired pressure within the vessel 2 in conjunction with oxidizer supply at 6.
  • the ballast supply at 8 is conventionally an emergency nitrogen ballast which may be fed directly into the vessel.
  • This same nitrogen ballast system may be used for back-filling the reaction a system when the decarburization and other gasing cycles are completed. It is possible to supply the ballast load for regulating the ambient pressure of the system through supply 8 though practical advantage is gained at 22.
  • the decarburization apparatus would also include flow measurement and control devices 32 in the oxidizer supply system being capable of measuring the flow of the oxidizer and control therefor, as well as any inert gases which may be also injected therein. Vacuum pressure gauges will be provided as at 34 to measure the vacuum within the vessel, as well as desirable control points within the steam ejector system such as preceding each ejector stage.
  • 01f gas analysis system is provided as is known in the art for measuring the particular off gases and the composition of the off gas according to its components.
  • similar flow control and measuring devices are necessary in line 22 as at 36 for the measure and control of the ballast supplied through line 22.
  • Suitable control and measuring means are commercially available and known in the art. It is also preferable to have a computer available to perform the calculation of the decarburization reaction to rapidly provide the calculation of the expected pressure according to the various parameters estab- 50 lished within the system.
  • maintaining said actual vessel pressure at least as great as said expected pressure includes reducing the quantity of oxidizing material introduced into the vesel while maintaining the flow rate of input gases constant, thereby maintaining a constant ambient pressure within said vessel.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
US751A 1970-01-05 1970-01-05 Method of controlling vacuum decarburization Expired - Lifetime US3700429A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US75170A 1970-01-05 1970-01-05

Publications (1)

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US3700429A true US3700429A (en) 1972-10-24

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US751A Expired - Lifetime US3700429A (en) 1970-01-05 1970-01-05 Method of controlling vacuum decarburization

Country Status (10)

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US (1) US3700429A (enExample)
JP (1) JPS5543047B1 (enExample)
AT (1) AT318675B (enExample)
BE (1) BE760724A (enExample)
CA (1) CA946163A (enExample)
DE (1) DE2061122C3 (enExample)
ES (1) ES386534A1 (enExample)
FR (1) FR2075921B1 (enExample)
GB (1) GB1335397A (enExample)
SE (1) SE392733B (enExample)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847593A (en) * 1971-07-13 1974-11-12 Centro Speriment Metallurg Process for refining metals, in particular liquid pig iron, in oxygen converters with continuous control of the operative procedure
US4251269A (en) * 1977-09-10 1981-02-17 Nisshin Steel Co., Ltd. Method for controlling steel making process under reduced pressures
US4427443A (en) 1979-11-28 1984-01-24 Etude Et Developpement En Metallurgie Process and apparatus for automating a vacuum degasification cycle for metal alloys
US5417739A (en) * 1993-12-30 1995-05-23 Ltv Steel Company, Inc. Method of making high nitrogen content steel
US5618490A (en) * 1992-12-18 1997-04-08 Mannesmann Aktiengesellschaft Vacuum installation, in particular for recycling metallurgy
US5830259A (en) * 1996-06-25 1998-11-03 Ltv Steel Company, Inc. Preventing skull accumulation on a steelmaking lance
US5865876A (en) * 1995-06-07 1999-02-02 Ltv Steel Company, Inc. Multipurpose lance
US5885323A (en) * 1997-04-25 1999-03-23 Ltv Steel Company, Inc. Foamy slag process using multi-circuit lance
WO2006067365A1 (en) * 2004-12-20 2006-06-29 The Boc Group Plc Method of degassing molten metal
US20090123414A1 (en) * 2004-12-13 2009-05-14 Cytos Biotechnology Ag Il-15 Antigen Arrays And Uses Thereof
CN115124161A (zh) * 2022-05-13 2022-09-30 华能山东发电有限公司烟台发电厂 一种延长发电机转子冷却水处理装置树脂使用周期的方法

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2438122A1 (de) * 1974-08-08 1976-02-19 Witten Edelstahl Verfahren zum vakuumentkohlen von metallschmelzen
JPS569319A (en) * 1979-07-05 1981-01-30 Nippon Steel Corp Vacuum treatment controller for molten steel
US4541862A (en) * 1982-11-30 1985-09-17 A. Finkl & Sons Co. Ladle steelmaking method and apparatus
RU2064660C1 (ru) * 1993-12-06 1996-07-27 Акционерное общество "Нижнетагильский металлургический комбинат" Устройство для контроля состояния зеркала расплавленного металла

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1343235A (fr) * 1962-12-21 1963-11-15 Nippon Kokan Kk Procédé pour la production de ferrochrome sans carbone
US3420657A (en) * 1966-02-14 1969-01-07 Union Carbide Corp Oxygen treatment of chromium alloys

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847593A (en) * 1971-07-13 1974-11-12 Centro Speriment Metallurg Process for refining metals, in particular liquid pig iron, in oxygen converters with continuous control of the operative procedure
US4251269A (en) * 1977-09-10 1981-02-17 Nisshin Steel Co., Ltd. Method for controlling steel making process under reduced pressures
US4427443A (en) 1979-11-28 1984-01-24 Etude Et Developpement En Metallurgie Process and apparatus for automating a vacuum degasification cycle for metal alloys
US5618490A (en) * 1992-12-18 1997-04-08 Mannesmann Aktiengesellschaft Vacuum installation, in particular for recycling metallurgy
US5417739A (en) * 1993-12-30 1995-05-23 Ltv Steel Company, Inc. Method of making high nitrogen content steel
US5865876A (en) * 1995-06-07 1999-02-02 Ltv Steel Company, Inc. Multipurpose lance
US5830259A (en) * 1996-06-25 1998-11-03 Ltv Steel Company, Inc. Preventing skull accumulation on a steelmaking lance
US5885323A (en) * 1997-04-25 1999-03-23 Ltv Steel Company, Inc. Foamy slag process using multi-circuit lance
US20090123414A1 (en) * 2004-12-13 2009-05-14 Cytos Biotechnology Ag Il-15 Antigen Arrays And Uses Thereof
WO2006067365A1 (en) * 2004-12-20 2006-06-29 The Boc Group Plc Method of degassing molten metal
US20080034922A1 (en) * 2004-12-20 2008-02-14 Bruce Simon H Method of Degassing Molten Metal
MD3997C2 (ro) * 2004-12-20 2010-07-31 Edwards Limited Dispozitiv şi procedeu de degazare a metalului topit (variante)
US7815845B2 (en) 2004-12-20 2010-10-19 Edwards Limited Method of degassing molten metal
CN115124161A (zh) * 2022-05-13 2022-09-30 华能山东发电有限公司烟台发电厂 一种延长发电机转子冷却水处理装置树脂使用周期的方法

Also Published As

Publication number Publication date
JPS5543047B1 (enExample) 1980-11-04
GB1335397A (en) 1973-10-24
DE2061122B2 (de) 1981-07-30
DE2061122C3 (de) 1982-11-25
BE760724A (fr) 1971-06-23
DE2061122A1 (de) 1971-07-15
FR2075921A1 (enExample) 1971-10-15
FR2075921B1 (enExample) 1974-09-20
AT318675B (de) 1974-11-11
CA946163A (en) 1974-04-30
ES386534A1 (es) 1973-11-16
SE392733B (sv) 1977-04-18

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AS Assignment

Owner name: ALLEGHENY LUDLUM CORPORATION

Free format text: CHANGE OF NAME;ASSIGNOR:ALLEGHENY LUDLUM STEEL CORPORATION;REEL/FRAME:004779/0642

Effective date: 19860805

AS Assignment

Owner name: PITTSBURGH NATIONAL BANK

Free format text: SECURITY INTEREST;ASSIGNOR:ALLEGHENY LUDLUM CORPORATION;REEL/FRAME:004855/0400

Effective date: 19861226

AS Assignment

Owner name: PITTSBURGH NATIONAL BANK

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. RECORDED ON REEL 4855 FRAME 0400;ASSIGNOR:PITTSBURGH NATIONAL BANK;REEL/FRAME:005018/0050

Effective date: 19881129