EP0174061A1 - Procédé continu de dégazage par le vide et de coulée de l'acier - Google Patents

Procédé continu de dégazage par le vide et de coulée de l'acier Download PDF

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Publication number
EP0174061A1
EP0174061A1 EP85303400A EP85303400A EP0174061A1 EP 0174061 A1 EP0174061 A1 EP 0174061A1 EP 85303400 A EP85303400 A EP 85303400A EP 85303400 A EP85303400 A EP 85303400A EP 0174061 A1 EP0174061 A1 EP 0174061A1
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EP
European Patent Office
Prior art keywords
metal
bath
tundish
molten metal
nozzle outlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP85303400A
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German (de)
English (en)
Inventor
William Lyon Sherwood
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Individual
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Individual
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Filing date
Publication date
Priority claimed from US06/610,884 external-priority patent/US4541865A/en
Application filed by Individual filed Critical Individual
Publication of EP0174061A1 publication Critical patent/EP0174061A1/fr
Withdrawn legal-status Critical Current

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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/113—Treating the molten metal by vacuum treating
    • 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
    • C21C5/56—Manufacture of steel by other methods
    • C21C5/567—Manufacture of steel by other methods operating in a continuous way

Definitions

  • the invention relates to the technology of steelmaking and, more particularly, to an improved method and apparatus for continuous vacuum degassing and casting of molten steel.
  • My United States Patent No. 3,514,280 describes continuous metal melting, withdrawal and discharge from a metal bath maintained within a rotary furnace emplying a siphon tube leading to an external chamber maintained under a negative pressure controlled in such a manner as to regulate the rate of metal discharge via the chamber.
  • my U.S. Patent Application No. 351,669 discloses a process for highly energy- efficient charge preheating, steelmaking, withdrawal and casting on a continuous basis, incorporating a more sophisticated vacuum withdrawal and post-treatment system for the molten steel for casting.
  • Effective steel degassing requires very high vacuum levels, that is, virtually complete evacuation, in combination with large exposed surface area-to-volume ratio, and it is an object of the present invention to most efficiently provide for initiating and maintaining of consistently high vacuum levels in the degassing operation.
  • Small passages, valves and flow adjustment devices can be subject to plugging by localized metal freezing and also by characteristic gradual build-ups of agglomerated non-metallic inclusion material from within the metal, as well as mechanical problems, and still another object is to reduce to a maximum of one the number of such flow restrictions in the molten metal sequence of movement after leaving the molten furnace bath.
  • the methods previously described utilize a secondary shut-off and seal ahead of, and in addition to, the casting gate or throttling valve, as necessary to provide for an initial starting vacuum and filling of the withdrawal apparatus with metal, and it is a still further object to eliminate the need for this secondary shut-off and seal.
  • the key element of the present invention is the closure and sealing of casting pool tundish from the outside atmosphere. This is provided in combination with sufficient degassing chamber height to accomodate molten metal column with a one-atmosphere ferrostatic head of metal above the highest furnace level, and elimination of flow limiting or controlling size restrictions of the furnace-to-vessel passage or vessel-to-tundish passage, to realize a more effective, simple and trouble-free system.
  • a gate valve (or valves) at the casting outlet(s) seal the system, allowing drawing of initial vacuum and fill-up with metal, and then the casting outlet(s) act as the only control point during operation.
  • the absence of other flow restriction renders any dimensional change in other parts of the system from erosion or thermal effects essentially irrelevant to the end operating result.
  • the method of the present invention thus incorporates methods for continuous vacuum processing and casting of molten steel and other metals in which a molten metal column is maintained with its top surface under vacuum in a continuous post-treatment vessel located adjacent to a continually replenished molten metal bath, with the column having a barometric height above the bath corresponding to the differential between prevailing atmospheric pressure on the bath surface and the vacuum pressure, and the column is fed with metal from the bath by way a tube with the inlet end inserted below and withdrawing metal from beneath the surface of the bath and the outlet directed into the column, and which includes a lateral extension of the lower portion of said column forming a pouring pool confined within a tundish chamber equipped with at least one nozzle outlet for pouring of metal at a level below the surface level of the molten bath; and in combination with these features introduces the step of sealing of the pouring pool apart from the outside atmosphere, thus substantially preventing any contact of the molten metal with the atmosphere during metal passage from within said bath, through said tube, column and pouring pool,
  • the top of the tundish is closed and sealed, the top level of metal therein does not affect the pressure at the nozzle inlet.
  • the overall rate of metal flow is substantially governed only by the size and characteristics of the nozzle and the ferrostatic head of of metal corresponding to the difference in metal level between the surface of the molten metal bath and the inlet to the nozzle.
  • the degassing column height or magnitude of the vacuum also do not directly influence the pressure at the nozzle.
  • a complete vacuum maintained over the column surface facilitates effective metal degassing and maintains a column with a constant differential of approximately 4h feet in height above the metal bath surface.
  • the method In combination with a complete closure for the tundish nozzle outlet opening, the method also provides a new and convenient means for creating initial vacuum and starting flow, by closing the nozzle opening with the effect of substantially sealing the tundish and vacuum chamber when in the pre-operational non-filled condition; evacuating the tundish and vacuum chamber to effect molten metal flow by movement from said bath through the tube into the degassing chamber and progressive filling of the chamber and tundish with molten metal up to the barometric height of the column; and then removing the closure from the nozzle outlet to allow metal discharge to begin and thereby establish the conditions of continuous vacuum degassing and pouring.
  • the metal may be introduced directly into a vertical continuous casting mold of a continuous casting machine.
  • the transfer passage may be sealed, extending the sealed metal path excluded from the atmosphere all the way from furnace-to-mold or even furnace-to-solidified casting in horizontal machines or covered-mold vertical (including curved mold) machines.
  • the withdrawal speed of the solidified casting from the casting machine is inherently the sole external control of molten metal flow rate in completely closed systems such as most horizontal casters, and this control also includes vertical (or curved mold) casters equipped with automatic tundish-to-mold level control, as now are prevalent in the art of continuous casting.
  • the invention also provides an apparatus for conducting the method comprising a continuous post-treatment vessel incorporating an enclosed vacuum degassing column chamber section, a metal withdrawal tube and a laterally extending tundish pouring section, the latter incorporating at least one nozzle outlet for molten metal and equipped with an enclosed and sealed cover in combination with the above.
  • the nozzle outlet is directed into a vertical (or curved) continuous casting machine mold, the nozzle opening being automatically regulated by closed- loop control maintaining a constant mold metal level.
  • discharge is direct from the tundish into a horizontal continuous casting mold, whereby there is not any molten metal exposure to atmosphere all the way from furnace to solidification, and the metal flow rate from the furnace through the withdrawal and degassing system is established solely by adjustments to the rate of withdrawing the solidified metal casting.
  • Prior post-treatment and handling systems in the art of ladle metallurgy, vacuum degassing and continuous casting include some form of external tundish level control and ladle flow control in open-shut or throttling mode, in which post-treatment vessels are filled and emptied and maintained by externally controlled devices.
  • the present invention eliminates need for these additional external controls, as the new method and apparatus inherently maintains balanced flow rates from molten furnace bath-to-casting, which correspond to the rate of withdrawal of the solidified casting. It is therefore only necessary to balance the casting withdrawal speed with the molten metal supply in the bath.
  • Figure 1 is a diagrammatic sectional view illustrating an embodiment of the method and apparatus of the invention featuring vertical continuous casting and having the tundish cover completely sealed from the atmosphere
  • Figure 2 is an alternative embodiment featuring horizontal continuous casting and providing for the option of exposing the tundish pool to atmospheric pressure, during continuous steady-state operation, after metal flow has been established.
  • a bath of molten metal 1 is maintained behind an annular dam restriciton 3 of the discharge opening of a rotary furnace 2, which is lined with refractory material 4 and heated by burner 5 to maintain the metal in molten condition.
  • a stationary barrier 6 equipped with gas-container seals 7 acts to limit interchange of heat and gases between the outside atmosphere and the furnace interior. Slag 8 which floats on the metal may be discharged by overflowing the annular discharge opening.
  • the metal withdrawal and degassing apparatus comprises the continuous post-treatment vessel 9 which incorporates the vacuum degassing column chamber section 10, the top part of which is evacuated by way of vacuum connection 11 employing ejectors or a vacuum pump.
  • the metal withdrawal tube 12 has its inlet end inserted down in molten bath, and the outlet connected into the degassing column chamber section 10 and can be equipped with a sliding shut-off valve 13.
  • the internal duct of withdrawal tube 12 preferably has a large enough cross section to avoid significant frictional pressure drop through the range of operation flow rates (excepting initial filling), whereby changes occurring in this cross-section, for example, through erosion by molten metal, do not have any significant influence on the operation.
  • a pouring tundish chamber section 14 projects laterally out from the lower portion of the column chamber section 10, and contains at least one pouring nozzle outlet 15 which is equipped with a slide-gate valve 16 for opening and closing to interupt flow of metals or gases through the nozzle.
  • the degassing column chamber section 10 most conveniently has a removable cover 17 to facilitate access and refractory repair, which is sealed, for example, by a water-cooled ring 18 carrying a circular seal 19 resting on sealing flange 20 extending around the degassing column chamber circumferences. Feeding of alloys and reagents into the degassing column is accomplished via a sealed conduit 21, and a sealed rotary gate valve 22 or, alternatively, a two-chamber vacuum lock, is employed to maintain a vacuum seal during transfer of the additive materials.
  • a porous refractory plug 23 supplied with stirring gas via valve 24 and pipe 25 may be included to assist in stirring and degassing of the column metal.
  • An injection lance 26, which may be water-cooled, may be included, and supplied with oxygen, carrier gas and additives by way of valve 27 and tube 28.
  • the pouring tundish chamber section 14 incorporates a top cover 32 which is sealed against the atmosphere during start-up and operation.
  • the cover preferably is removable to facilitate refractory repair and replacement, and the cover perimeter 36 is sealed with refractory mortar and/or a sealing compound during placement prior to operation.
  • a supplementary seal may also be provided, for example, by a water-cooled ring and seal pressed against a : sealing flange, in a manner similar to that for column section cover 17.
  • a refractory wall barrier 33 may be incorporated into the assembly to restrict free mixing of molten metal between vacuum degassing column chamber section 10 and tundish chamber section 14.
  • the required metal transfer passages 34,35 can have a very small cross section relative to the junction area between column and tundish sections to substantially prevent short circuiting of inadequately reacted and non-degassed metal from the degassing column section 10 into the pouring tundish section 14, although not so small so as to result in a significant frictional flow pressure drop.
  • the pouring nozzle outlet 15 from the ; tundish discharges directly into a vertical water-cooled mold 29 of a vertical (or curved) continuous casting machine, from which the partially solidified casting 30 is typically withdrawn by a withdrawal mechanism having an adjustable and controlled withdrawal speed which is located below and beyond a water-cooled spray chamber adapted to complete the metal solidification process.
  • the stream from tundish-to-mold is separated from the atmosphere by a ceramic shroud 31.
  • FIG. 2 shows an alternative embodiment including a tundish cover aperture 37 equipped with another slide-gate valve 38 for making and breaking the tundish cover seal
  • the top metal passage 34 from column-to-tundish has been eliminated, leaving only. passage 35 which is fully at a level lower than the surface of molten bath 1, whereby operation can be initiated simply by closing of shut-off valve 13 prior to start-up, followed by near complete evacuation of the continuous post-treatment vessel before re-opening valve 13 to effect filling of the vessel.
  • the tundish cover aperture 27 could be opened and operate subsequently with the ambient air or artificial atmosphere above the metal surface. In the absence of significant frictional pressure losses from molten metal flow through withdrawal tube 12 or passage 35, the top surface of the metal in pouring tundish chamber 14 then would coincide with the surface level of molten bath 1.
  • Figure 2 also shows a tundish-pool shrouding arrangement whereby low-pressure inert or reducing gas such as argon is introduced at inlet 40 to fill tube 39 and the space 41 over the tundish pouring pool, utilizing restricted exit 42 to maintain slight positive pressure and exclude the surrounding air.
  • Rotary valve 43 is illustrated as an example of a method of introducing reagents into the tundish. Continuously fed wire, as well known in the art, is another obvious alternative for adding materials. Should substantial quantities of slag-forming constituents be necessary for metallurgical reasons, a slag-spout sealed by a temporary barrier (not shown) would also be indicated.
  • FIG. 2 also illustrates diagrammatically the connection into a horizontal continuous caster.
  • Tundish nozzle outlet 15 leads directly into break-ring 44 forming the inlet to water-cooled mold 45, the metal path at the tundish-mold junction being entirely separated from contact with the surrounding atmosphere.
  • the embodiment shown effects the necessary seal for initial post-treatment vessel evacuation and filling by means of sealing the clearance between the dummy bar head and the inner mold walls at the outset,
  • Horizontal casters also have included a slide-gate valve between the tundish nozzle outlet and the break ring .(not illustrated), which would provide a primary closure and seal, the dummy bar then being a secondary one.
  • the continuous post-treatment vessel assembly as in Figure 1 is prepared and moved into position with the withdrawal tube inserted into the furnace and both tube slide-gate 13 and nozzle slide-gate 1'alve 16 closed, and a vacuum is created through vacuum line 11.
  • slide-gate 13 With the inlet of withdrawal tube 12 submerged in bath 1, slide-gate 13 is opened, drawing the metal in to progressively fill the tundish chamber section 10 and then the column chamber section 11, up to the barometric height above bath 1, according to the vacuum pressure effected.
  • the slide-gate 16 is opened allowing flow from tundish to mold by way of pouring nozzle outlet 15. This procedure forms and establishes a continuous sealed flow-path of molten metal within the post-treatment vessel 9 extending from within the furnace bath 1 all the way through to the nozzle outlet 15, and hence into the continuous casting mold.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Continuous Casting (AREA)
EP85303400A 1984-05-16 1985-05-15 Procédé continu de dégazage par le vide et de coulée de l'acier Withdrawn EP0174061A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/610,884 US4541865A (en) 1984-05-16 1984-05-16 Continuous vacuum degassing and casting of steel
US610884 1984-05-16

Publications (1)

Publication Number Publication Date
EP0174061A1 true EP0174061A1 (fr) 1986-03-12

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EP85303400A Withdrawn EP0174061A1 (fr) 1984-05-16 1985-05-15 Procédé continu de dégazage par le vide et de coulée de l'acier

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EP (1) EP0174061A1 (fr)
AU (1) AU582787B2 (fr)
CA (1) CA1226717A (fr)
GB (1) GB2159076B (fr)
IN (1) IN164566B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0566867A1 (fr) * 1992-04-18 1993-10-27 VAW Aluminium AG Procédé et appareil de fabrication d'alliages d'aluminium non-poreux et dégazés
RU2132524C1 (ru) * 1998-10-13 1999-06-27 Уральский государственный технический университет Плавильно-рафинировочный агрегат
CN108676962A (zh) * 2018-06-11 2018-10-19 江苏集萃先进金属材料研究所有限公司 一种高性能合金超纯净化真空感应熔炼系统及其使用方法
CN111618291A (zh) * 2020-06-02 2020-09-04 中国重型机械研究院股份公司 一种炼钢连铸无氧管道输送装置及方法
WO2023241988A1 (fr) * 2022-06-15 2023-12-21 Sms Group Gmbh Dispositif de dégazage destiné à dégazer un courant de coulée de métal en fusion

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3617303A1 (de) * 1986-05-23 1987-11-26 Leybold Heraeus Gmbh & Co Kg Verfahren zum einschmelzen und entgasen von stueckigem material
AT515235A1 (de) * 2013-12-30 2015-07-15 Inteco Special Melting Technologies Gmbh Verfahren und Anordnung zum Vakuumblockguss
CN113245537A (zh) * 2021-06-30 2021-08-13 永兴特种材料科技股份有限公司 一种中包分体式水口烘烤炉
DE102023206735A1 (de) * 2023-07-14 2025-01-16 Sms Group Gmbh Vorrichtung und Verfahren zur Entgasung von Schmelzen in Stranggießanlagen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1332324A (fr) * 1961-08-09 1963-07-12 Procédé de transport et de dégazage d'une masse en fusion
FR1589176A (fr) * 1967-09-28 1970-03-23
US3514280A (en) * 1967-10-19 1970-05-26 Sherwood William L Continuous steelmaking method
DE1960283A1 (de) * 1968-12-18 1970-07-09 Pennwalt Corp Vakuumentgasungsvorrichtung fuer die Verwendung beim Stranggiessen von Metallen und Verfahren zum Stranggiessen von schmelzfluessigem Metall,waehrend es einer Vakuumentgasung unterworfen ist
GB2121829A (en) * 1982-02-24 1984-01-04 Sherwood William L Continuous steelmaking and casting
EP0134336A1 (fr) * 1983-08-16 1985-03-20 William Lyon Sherwood Procédé pour produire et couler en continu de l'acier

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1965136B1 (de) * 1969-12-27 1971-02-25 Standard Messo Duisburg Vorrichtung zur Pfannen-Entgasung von Stahl- oder anderen Metallschmelzen
US4105438A (en) * 1977-04-19 1978-08-08 Sherwood William L Continuous metal melting, withdrawal and discharge from rotary furnaces

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1332324A (fr) * 1961-08-09 1963-07-12 Procédé de transport et de dégazage d'une masse en fusion
FR1589176A (fr) * 1967-09-28 1970-03-23
US3514280A (en) * 1967-10-19 1970-05-26 Sherwood William L Continuous steelmaking method
DE1960283A1 (de) * 1968-12-18 1970-07-09 Pennwalt Corp Vakuumentgasungsvorrichtung fuer die Verwendung beim Stranggiessen von Metallen und Verfahren zum Stranggiessen von schmelzfluessigem Metall,waehrend es einer Vakuumentgasung unterworfen ist
GB2121829A (en) * 1982-02-24 1984-01-04 Sherwood William L Continuous steelmaking and casting
EP0134336A1 (fr) * 1983-08-16 1985-03-20 William Lyon Sherwood Procédé pour produire et couler en continu de l'acier

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0566867A1 (fr) * 1992-04-18 1993-10-27 VAW Aluminium AG Procédé et appareil de fabrication d'alliages d'aluminium non-poreux et dégazés
US5330555A (en) * 1992-04-18 1994-07-19 Vaw Aluminium Ag Process and apparatus for manufacturing low-gas and pore-free aluminum casting alloys
TR26957A (tr) * 1992-04-18 1994-09-12 Vaw Ver Aluminium Werke Ag Zayif gaz muhtevali ve gözeneksiz alüminyum döküm alasimlarinin imaline iliskin yöntem ve düzenleme.
RU2132524C1 (ru) * 1998-10-13 1999-06-27 Уральский государственный технический университет Плавильно-рафинировочный агрегат
CN108676962A (zh) * 2018-06-11 2018-10-19 江苏集萃先进金属材料研究所有限公司 一种高性能合金超纯净化真空感应熔炼系统及其使用方法
CN108676962B (zh) * 2018-06-11 2020-11-24 江苏集萃先进金属材料研究所有限公司 一种高性能合金超纯净化真空感应熔炼系统及其使用方法
CN111618291A (zh) * 2020-06-02 2020-09-04 中国重型机械研究院股份公司 一种炼钢连铸无氧管道输送装置及方法
WO2023241988A1 (fr) * 2022-06-15 2023-12-21 Sms Group Gmbh Dispositif de dégazage destiné à dégazer un courant de coulée de métal en fusion

Also Published As

Publication number Publication date
AU4753685A (en) 1987-03-19
GB2159076B (en) 1989-02-08
IN164566B (fr) 1989-04-08
GB8512239D0 (en) 1985-06-19
AU582787B2 (en) 1989-04-13
GB2159076A (en) 1985-11-27
CA1226717A (fr) 1987-09-15

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