US3297311A - Apparatus for degasifying liquid metal - Google Patents

Apparatus for degasifying liquid metal Download PDF

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Publication number
US3297311A
US3297311A US408011A US40801164A US3297311A US 3297311 A US3297311 A US 3297311A US 408011 A US408011 A US 408011A US 40801164 A US40801164 A US 40801164A US 3297311 A US3297311 A US 3297311A
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Prior art keywords
ladle
cover
molten metal
vacuum tank
heat insulating
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Expired - Lifetime
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US408011A
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Stenkvist Sven-Einar
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ABB Norden Holding AB
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ASEA AB
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/04—Refining by applying a vacuum
    • 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
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • C21C5/5241—Manufacture of steel in electric furnaces in an inductively heated furnace
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/04—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated adapted for treating the charge in vacuum or special atmosphere
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • a device which consists of a plate of heat couducting, electrical conducting material, preferably graphite and of a heat insulating, heat resistant coating upon this plate ⁇ as well as an electrical heating device which rests upon this insulating coating.
  • the whole device can be raised and lowered above the ingot.
  • the purpose of this device is to make it possible for the top of the ingot to be kept above the solidication temperature for a certain predetermined time.
  • the invention is based on the use of this idea within another metallurgical field of use, namely degassing in a ladle.
  • the invention relates to a ladle or chill which contains molten steel or another metal or metal alloy.
  • a ladle or chill which contains molten steel or another metal or metal alloy.
  • it has usually been difficult to avoid heat losses particularly as it is not practical during degassing to have a heat insulating slag covering the surface of the melt.
  • an inductive, low frequency stirrer is placed and the invention is characterised in that at the upper part of the ladle a raisable and lowerable cover or a plate of heat conducting, electrical conducting material with good resistance to temperature losses, preferably graphite, is situated, and that on this plate is arranged a heat insulating layer and over ⁇ and/or in this an electrical induction heating device.
  • the plate or cover should suitably have a shape mainly corresponding to the upper inner section of the ladle. Such an arrangement gives a reduced heat radiation from the molten metal.
  • the heating from the cover can be of different amounts. With the help of the stirrer the molten surface can continually be renewed and the temperature is kept constant. In this way for example overheating of the molten surface can be avoided.
  • the raisability and lowerabilty of the cover/plate makes it possible for this to be positioned more closely to the molten surface.
  • the possibility of degassing to a high degree of a melt handled in this manner becomes important, since time is not important to the same extent as previously when the temperature fall in the molten metal was considerable.
  • the stirring except for the temperature equalising effect, gives an intensified degassing. As is known, vacuum degassing of non-moving molten metal is not so effective in the bottom layers as on the surface layer. With stirring in the ladle the total degassing becomes greater.
  • the drawing shows an embodiment of the invention.
  • a ladle 12 situated in a gas tight closable tank 11 for molten steel or 'another metal or metal alloy. From the tank one or more gas evacuation conduits 18 are connected to one or more evacuation pumps, not shown.
  • a low frequency (0.2- cycles per second) multi-phase stirrer 13 of known construction is arranged at the side of the ladle and/or beneath it. Stirring can also be produced from the heating coil described below either through separate windings in this, superimposing of low frequency 3,297,3ll Patented Jan. l0, 1967 current upon the high frequency heating current or by alternately feeding by high and low frequen-cy current.
  • high frequency we mean here a current with a frequency above 60 cycles per second.
  • a graphite cover or plate 17 (which can also be of another heat conducting, electrical conducting material impervious to heat up to high temperatures) with a good fit to the upper part of the ladle 12, raisable or lowerable by means of screw devices 14, 15.
  • a heat insulating layer 19 Above the plate 17 is arranged a heat insulating layer 19 and on this is arranged an electrical heating winding 20.
  • Vacuum treatment of molten metal, such as steel is carried out in the following way:
  • the ladle 12 with its molten contents is placed in the tank 11, which is connected and evacuated to less than 50 Torr by the pipe 18 during stirring (from 13).
  • the cover 17, 19 with heating dinwings is lowered to a position close to the surface of the molten metal and heating current is switched on by means of which the surface is continually heated and at the same time continuously renewed.
  • This surface becomes degassed and the gasses are evacuated mainly in the space between the plate and the ladle wall.
  • the plate can, of course, be lifted up and possibly turned aside so that the degassing effect is further increased.
  • the vacuum tank must, of course, be modified from the form shown in the figure.
  • the turning can also possibly be made at intervals with intermediate heating of the molten surface by the plate.
  • the tapping of molten metal can either be made through a closable tap hole in the ladle and tank bottom or also by tipping the ladle, possibly after lifting it from the tank, but it is, of course, feasible to arrange in a way known per se, tipping under vacuum through a gutter or the like (not shown).
  • Device for refining molten metal such as steel comprising a ladle for said molten metal, a vacuum tank, said ladle being inclosed in said vacuum tank, at least one electromagnetic, multi-phase -stirrer for developing frequencies between 0.2 ⁇ and 10 cycles per second at one side of said ladle, a cover of heat conducting material with good temperature resistivity being positioned at the upper part of the ladle Within said vacuum tank, means for raising and lowering said cover, said cover being provided at its upper surface with a heat insulating layer and an electrical induction heating coil, said induction heating coil being positioned adjacent the heat insulating layer.

Description

Jal 10, 1957 svEN-ElNAR s'rENKvlsT 3,297,311
APPARATUSFOR DEGASIFYING LIQUID METAL Filed Nov. 2, 1964 INVENTOR. .5v5 N- E M//M' 57E/nrw S7' BY* i 'E Mg m United States Patent C) M 3,297,311 'APPARATUS FOR DEGASIFYING LIQUID METAL Sven-Einar Stenkvist, Croton-on-Hudson, N.Y., assignor to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Filed Nov. 2, 1964, Ser. No. 408,011 Claims priority, application Sweden, Nov. 11, 1963, 12,383/ 63 3 Claims. (Cl. 266-34) In order to counteract forming of pipes in ingots a device is known which consists of a plate of heat couducting, electrical conducting material, preferably graphite and of a heat insulating, heat resistant coating upon this plate `as well as an electrical heating device which rests upon this insulating coating. The whole device can be raised and lowered above the ingot. The purpose of this device is to make it possible for the top of the ingot to be kept above the solidication temperature for a certain predetermined time. The invention is based on the use of this idea within another metallurgical field of use, namely degassing in a ladle.
The invention relates to a ladle or chill which contains molten steel or another metal or metal alloy. In such ladles, for example in connection with degassing of their molten contents, it has usually been difficult to avoid heat losses particularly as it is not practical during degassing to have a heat insulating slag covering the surface of the melt. Close to or beneath the ladle according to the invention an inductive, low frequency stirrer is placed and the invention is characterised in that at the upper part of the ladle a raisable and lowerable cover or a plate of heat conducting, electrical conducting material with good resistance to temperature losses, preferably graphite, is situated, and that on this plate is arranged a heat insulating layer and over `and/or in this an electrical induction heating device. The plate or cover should suitably have a shape mainly corresponding to the upper inner section of the ladle. Such an arrangement gives a reduced heat radiation from the molten metal.
The heating from the cover can be of different amounts. With the help of the stirrer the molten surface can continually be renewed and the temperature is kept constant. In this way for example overheating of the molten surface can be avoided. The raisability and lowerabilty of the cover/plate makes it possible for this to be positioned more closely to the molten surface. The possibility of degassing to a high degree of a melt handled in this manner becomes important, since time is not important to the same extent as previously when the temperature fall in the molten metal was considerable. The stirring, except for the temperature equalising effect, gives an intensified degassing. As is known, vacuum degassing of non-moving molten metal is not so effective in the bottom layers as on the surface layer. With stirring in the ladle the total degassing becomes greater. The drawing shows an embodiment of the invention.
In the accompanying figure is shown schematically a ladle 12, situated in a gas tight closable tank 11 for molten steel or 'another metal or metal alloy. From the tank one or more gas evacuation conduits 18 are connected to one or more evacuation pumps, not shown. At the side of the ladle and/or beneath it, a low frequency (0.2- cycles per second) multi-phase stirrer 13 of known construction (cylindrical stirrer or one or more plane stirrers) is arranged. Stirring can also be produced from the heating coil described below either through separate windings in this, superimposing of low frequency 3,297,3ll Patented Jan. l0, 1967 current upon the high frequency heating current or by alternately feeding by high and low frequen-cy current. By high frequency we mean here a current with a frequency above 60 cycles per second.
Under the upper wall or cover 16 of the tank there is arranged a graphite cover or plate 17 (which can also be of another heat conducting, electrical conducting material impervious to heat up to high temperatures) with a good fit to the upper part of the ladle 12, raisable or lowerable by means of screw devices 14, 15. Above the plate 17 is arranged a heat insulating layer 19 and on this is arranged an electrical heating winding 20.
Vacuum treatment of molten metal, such as steel, is carried out in the following way:
The ladle 12 with its molten contents is placed in the tank 11, which is connected and evacuated to less than 50 Torr by the pipe 18 during stirring (from 13). The cover 17, 19 with heating dinwings is lowered to a position close to the surface of the molten metal and heating current is switched on by means of which the surface is continually heated and at the same time continuously renewed. This surface becomes degassed and the gasses are evacuated mainly in the space between the plate and the ladle wall. During a part of the degassing time the plate can, of course, be lifted up and possibly turned aside so that the degassing effect is further increased. For such turning the vacuum tank must, of course, be modified from the form shown in the figure. The turning can also possibly be made at intervals with intermediate heating of the molten surface by the plate.
The tapping of molten metal can either be made through a closable tap hole in the ladle and tank bottom or also by tipping the ladle, possibly after lifting it from the tank, but it is, of course, feasible to arrange in a way known per se, tipping under vacuum through a gutter or the like (not shown).
The invention can be varied in many ways within the scope of the following claims.
What is claimed is:
1. Device for refining molten metal such as steel, said device comprising a ladle for said molten metal, a vacuum tank, said ladle being inclosed in said vacuum tank, at least one electromagnetic, multi-phase -stirrer for developing frequencies between 0.2 `and 10 cycles per second at one side of said ladle, a cover of heat conducting material with good temperature resistivity being positioned at the upper part of the ladle Within said vacuum tank, means for raising and lowering said cover, said cover being provided at its upper surface with a heat insulating layer and an electrical induction heating coil, said induction heating coil being positioned adjacent the heat insulating layer.
2. Device according to claim 1, in which said ladle is positioned in a vacuum-tight closable tank evacuable to a pressure of less than 50 torr.
3. Device according to claim 1, in which said cover has a form substantially corresponding with the inner section of the upper part of said ladle.
References Cited by the Examiner UNITED STATES PATENTS 2,859,262 1l/l958 Harders et al. 266-34 3,027,150 3/ 1962 Harders 266-34 3,239,204 3/ 1966 Hokanson 266-34 JOHN F. CAMPBELL, Primary Examiner.
M. L. FAIGUS, Assistant Examiner.

Claims (1)

1. DEVICE FOR REFINING MOLTEN METAL SUCH AS STEEL, SAID DEVICE COMPRISING A LADLE FOR SAID MOLTEN METAL, A VACUUM TANK, SAID LADLE BEING INCLOSED IN SAID VACUUM TANK, AT LEAST ONE ELECTROMAGNETIC, MULTI-PHASE STIRRER FOR DEVELOPING FREQUENCIES BETWEEN 0.2 AND 10 CYCLES PER SECOND AT ONE SIDE OF SAID LADLE, A COVER OF HEAT CONDUCTING MATERIAL WITH GOOD TEMPERATURE RESISTIVITY BEING POSITIONED AT THE UPPER PART OF THE LADLE WITHIN SAID VACUUM TANK, MEANS FOR RAISING AND LOWERING SAID COVER, SAID COVER BEING PROVIDED AT ITS UPPER SURFACE WITH A HEAT INSULATING LAYER AND AN ELECTRICAL INDUCTION HEATING COIL, SAID INDUCTION HEATING COIL BEING POSITIONED ADJACENT THE HEAT INSULATING LAYER.
US408011A 1963-11-11 1964-11-02 Apparatus for degasifying liquid metal Expired - Lifetime US3297311A (en)

Applications Claiming Priority (1)

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SE12383/63A SE311533B (en) 1963-11-11 1963-11-11

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DE (1) DE1433406B2 (en)
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3382912A (en) * 1964-11-18 1968-05-14 John Mohr And Sons Apparatus for conserving heat, degassing and casting molten metal
US4276082A (en) * 1979-02-09 1981-06-30 Bbc Brown, Boveri & Company, Limited Process for the heating and/or melting of metals and an induction furnace to carry out the process
US4986517A (en) * 1988-12-20 1991-01-22 Rolls-Royce Plc Apparatus for pouring molten metals
US4995593A (en) * 1988-12-20 1991-02-26 Rolls-Royce Plc Crucible having a movable dross collector comprising an induction coil
US5974077A (en) * 1906-10-04 1999-10-26 Shinko Electric Co., Ltd. Method of refining metal to high degree of purity and high-frequency vacuum induction melting apparatus
US20030189965A1 (en) * 2002-04-04 2003-10-09 Miller Douglas J. Induction furnace for high temperature operation

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU605949B2 (en) * 1987-12-25 1991-01-24 Nkk Corporation Method for cleaning molten metal and apparatus therefor
JPH04202710A (en) * 1990-11-30 1992-07-23 Daido Steel Co Ltd Vacuum refining method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2859262A (en) * 1955-09-05 1958-11-04 Hoerder Huettenunion Ag Apparatus for degasifying liquid metal
US3027150A (en) * 1958-03-10 1962-03-27 Hoerder Huettenunion Ag Apparatus for treating steel melts
US3239204A (en) * 1963-02-05 1966-03-08 Pennsalt Chemicals Corp Vacuum degassing apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2859262A (en) * 1955-09-05 1958-11-04 Hoerder Huettenunion Ag Apparatus for degasifying liquid metal
US3027150A (en) * 1958-03-10 1962-03-27 Hoerder Huettenunion Ag Apparatus for treating steel melts
US3239204A (en) * 1963-02-05 1966-03-08 Pennsalt Chemicals Corp Vacuum degassing apparatus

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5974077A (en) * 1906-10-04 1999-10-26 Shinko Electric Co., Ltd. Method of refining metal to high degree of purity and high-frequency vacuum induction melting apparatus
US3382912A (en) * 1964-11-18 1968-05-14 John Mohr And Sons Apparatus for conserving heat, degassing and casting molten metal
US4276082A (en) * 1979-02-09 1981-06-30 Bbc Brown, Boveri & Company, Limited Process for the heating and/or melting of metals and an induction furnace to carry out the process
US4986517A (en) * 1988-12-20 1991-01-22 Rolls-Royce Plc Apparatus for pouring molten metals
US4995593A (en) * 1988-12-20 1991-02-26 Rolls-Royce Plc Crucible having a movable dross collector comprising an induction coil
GB2227693B (en) * 1988-12-20 1992-09-30 Rolls Royce Plc Combined crucible and dross collector
US20030189965A1 (en) * 2002-04-04 2003-10-09 Miller Douglas J. Induction furnace for high temperature operation
WO2003087689A1 (en) 2002-04-04 2003-10-23 Ucar Carbon Company, Inc. Induction furnace for high temperature operation
US6724803B2 (en) * 2002-04-04 2004-04-20 Ucar Carbon Company Inc. Induction furnace for high temperature operation
US20050013339A1 (en) * 2002-04-04 2005-01-20 Miller Douglas J. Induction furnace for high temperature operation
US6898232B2 (en) 2002-04-04 2005-05-24 Ucar Carbon Company Inc. Induction furnace for high temperature operation
CN1659415B (en) * 2002-04-04 2010-05-26 格拉弗技术国际控股有限公司 Induction furnace for high temperature operation

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Publication number Publication date
GB1078102A (en) 1967-08-02
SE311533B (en) 1969-06-16
DE1433406B2 (en) 1970-09-17
DE1433406A1 (en) 1970-09-17

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