EP0150226B1 - Procédé et installation pour minimiser la formation d'écume pendant la chute libre du métal liquide dans les moules, goulottes ou autres récipients - Google Patents

Procédé et installation pour minimiser la formation d'écume pendant la chute libre du métal liquide dans les moules, goulottes ou autres récipients Download PDF

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Publication number
EP0150226B1
EP0150226B1 EP19830113078 EP83113078A EP0150226B1 EP 0150226 B1 EP0150226 B1 EP 0150226B1 EP 19830113078 EP19830113078 EP 19830113078 EP 83113078 A EP83113078 A EP 83113078A EP 0150226 B1 EP0150226 B1 EP 0150226B1
Authority
EP
European Patent Office
Prior art keywords
moulds
molten metal
aperture
mould
cover plate
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.)
Expired
Application number
EP19830113078
Other languages
German (de)
English (en)
Other versions
EP0150226A1 (fr
Inventor
Edouard Gervais
Henri Levert
Laurence C. Smyth
George Deep
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Noranda Inc
Original Assignee
Noranda Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to AU22592/83A priority Critical patent/AU560253B2/en
Application filed by Noranda Inc filed Critical Noranda Inc
Priority to EP19830113078 priority patent/EP0150226B1/fr
Priority to DE8383113078T priority patent/DE3374279D1/de
Priority to JP25250083A priority patent/JPS60145262A/ja
Publication of EP0150226A1 publication Critical patent/EP0150226A1/fr
Application granted granted Critical
Publication of EP0150226B1 publication Critical patent/EP0150226B1/fr
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D5/00—Machines or plants for pig or like casting
    • B22D5/04—Machines or plants for pig or like casting with endless casting conveyors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
    • B22D21/02—Casting exceedingly oxidisable non-ferrous metals, e.g. in inert atmosphere
    • B22D21/027—Casting heavy metals with low melting point, i.e. less than 1000 degrees C, e.g. Zn 419 degrees C, Pb 327 degrees C, Sn 232 degrees C
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/003—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting by using inert gases

Definitions

  • This invention relates to a process for minimizing foam formation on the top surface of molten metal during pouring of the metal into moulds or similar containers, or during free falling of molten metal from a furnace to a launder, or cascading of the metal from launder to launder.
  • the non-oxidizing atmosphere is preferably provided by an inert gas, such as nitrogen, and it can contain a small quantity of oxygen, e.g. up to 2% without producing excessive quantities of bubbles.
  • the above disclosed method may be carried out by placing a cover on the top of the molten metal container, and by providing an aperture therein for passage of the molten metal and means for introducing a non-oxidizing gas under the cover.
  • the above disclosed method could also be carried out on a continuous slab casting machine comprising a train of closely spaced open top ingot moulds mounted on an endless conveyor chain by providing a hood over the casting machine at the filling station and introducing a non-oxidizing gas under the hood. Seals would be required at the hood entrance and exit as well as on the sides to prevent excessive loss of non-oxidizing gas.
  • the hood would of course require a sealed opening for introducing the molten metal through one of the walls thereof.
  • the above disclosed method could additionally be carried out on a continuous slab casting machine by an apparatus as disclosed in EP-A-0,088,701 which comprises a hood or a cover located at a small distance above the travelling moulds and adapted to cover two adjacent moulds.
  • the cover has an opening in the top thereof for introducing molten into the moulds as well as an opening in the side for introducing a non-oxidizing under the cover.
  • this apparatus does not allow an adequate distribution of the non-oxidizing gas in the moulds.
  • the apparatus in accordance with the present invention comprises a cover plate located at a predetermined distance above a number of containers or ingot moulds and having an aperture therein for casting molten metal in each container as they pass under the aperture.
  • the cover plate extends over several moulds located before and several moulds located after said aperture and has a plurality of ports longitudinally spaced therein and over each mould for feeding a non-oxidizing gas through the cover plate so as to progressively develop a non-oxidizing atmosphere in the moulds as they approach the aperture in the cover plate and to maintain such atmosphere in the moulds as they pass beyond said aperture.
  • the entrance length of the cover plate before the mould filling aperture is necessary to progressively develop the required non-oxidizing atmosphere while the exit length of the cover plate is needed to maintain the required non-oxidizing atmosphere.
  • the entrance length is determined by the conveyor line speed, the container volume, the container to cover gap and the influence of these factors on the volume of purging gas required to obtain the desired atmosphere.
  • the exit length is determined by the pneumatic resistance required to prevent back flow of air into the container being filled.
  • the laboratory apparatus comprises a bottom-pouring tundish 10 which is used to feed molten zinc into a slab mould 12 through a cover 14 closing the top of the mould.
  • the bottom of the tundish is provided with an opening registering with a corresponding opening in the cover 14 and is sealed to the cover by any suitable means such as by welding.
  • the opening in the bottom of the tundish is closed by a plug valve 16 which may be opened when it is desired to pour molten metal into the mould.
  • the cover is sealed to the mould by '0' ring 18.
  • a metered nitrogen inlet 20 and exhaust vent 22 are provided through the cover to maintain a suitable non-oxidizing atmosphere on the top surface of the mould.
  • a preliminary experimental procedure was carried out involving filling the tundish with molten zinc and then opening the valve to fill the mould. A fair amount of foam was formed on the top of the molten metal. The same procedure was repeated except that the covered mould was purged with nitrogen before opening the valve to fill the mould. The mould was uncovered soon after filling, before solidification to allow freezing of metal in air. No foam appeared on top of the molten metal.
  • the invention may also be carried out on a continuous slab casting machine, such as the Sheppard casting machine which has a number of moulds mounted on an endless conveyor chain.
  • the non-oxidizing atmosphere may be provided by means of a hood surrounding the casting machine at the filling station. Molten metal would be fed from the furnace to a pouring ladle located inside the hood and from the pouring ladle into the moulds as they move past the filling station.
  • a metered nitrogen inlet and exhaust vent would be provided through the hood to provide a non-oxidizing atmosphere in the hood.
  • the nitrogen atmosphere within the hood must be maintained at a slight positive pressure such that the ambient oxidizing atmosphere outside the hood cannot enter the hood through the mould entrance and exit ports. However, seals would be required at the hood entrance and exit to prevent excessive loss of nitrogen gas.
  • FIG. 2 there is shown a train of closely spaced open top ingot moulds 30 mounted on an endless conveyor chain 32 moving at a line speed of about 5 cm/sec. in the direction indicated by arrow A.
  • the ingot moulds all have flat top surfaces.
  • a stationary cover plate 34 is mounted adjacent to but spaced by a predetermined distance D from the top surface of the moulds and covers a predetermined number of moulds before and after a metal pouring station which is mounted on the top of the cover plate.
  • the metal pouring station is a conventional design comprising a launder 36 which ends with a downspout 38 used to feed molten metal into a ladle 40.
  • the ladle 40 is intermittently pivoted to successively pour metal into each mould through a pouring slot 42 in the cover plate.
  • a trap 44 is positioned at the end of the launder to capture dross which may be floating on the surface of the molten metal.
  • the cover plate 34 is provided with a predetermined number of gas inlet ports 46 and an inert gas is fed into such ports through a front manifold 48 and a main manifold 50.
  • Inert gas is fed to the front mould entering under the plate through three gas inlet ports to rapidly purge the moulds, and to the remaining moulds under the plate through a single row of ports to progressively lower and maintain the oxygen level at the pouring station below a predetermined value.
  • An auxiliary manifold 52 is also provided for feeding inert gas to the ladle enclosure 54 and the downspout enclosure 56. Cover strips 58 are placed on the gaps between the moulds so as to prevent excessive leakage of gas through such gaps.
  • the width of the plate 34 is equal to that of moulds 30. Inert gas enters the moulds at gas ports 46 and flows out through the gaps at the sides and the ends of the cover plate.
  • the width of the cover as well as the width of the container with respect to the container cavity are dependent on the pneumatic resistance required to prevent back flow of air into the moulds.
  • the tests were carried out by establishing a predetermined nitrogen flow rate through the cover plate and then traversing the moulds past the cover plate at the same speed as a conventional casting machine conveyor (5 cm/sec.). Each mould was progressively purged as it entered under the cover plate. The mould atmosphere was sampled in the centre of the mould by pumping a sample to an oxygen analyser as the mould approached the pouring slot.
  • Atmosphere tests were initially carried out with the machine in operation but without pouring liquid metal. These tests indicated that oxygen levels could be maintained at the pouring station in the range of 0.3-0.5% and that no gain could be achieved by increasing the nitrogen flow rate above 56.7 Nm 3 h.
  • Liquid zinc was then started up with preheating flames on the launder and ladle. Nitrogen was first delivered at 7.1 Nm 3 h to the front manifold and at 42.5 Nm 3 h to the main manifold of the cover plate and successively to the ladle and downspout enclosures at 7.1 Nm 3 h. The oxygen level maintained at the pouring station was in the range of 0.35-0.45%.
  • the slab ingot surfaces were seen to be bright and dross-free.
  • Transparent oxide films identical to those obtained in the laboratory tests using oxygen levels in the range of 0.2-0.5% were observed on the slabs.
  • Figures 7, 8 and 9 show refinements to reduce loss of gas in between the moulds and so reduce the gas flow requirements.
  • the edges of the moulds are thicker than that shown in Figure 2 and this increases the resistance to gas flow in the gap 60 between the moulds.
  • the edges of the moulds are designed so that the gap 62 is horizontal in order to prevent direct flow of the gas from the cover ports. This design is in a way equivalent to the cover strips 58 of Figure 2 but is much more resistant to wear and tear.
  • Figure 9 shows another method of reducing gas flow which involves the use of a seal 64 in between the moulds. This alternative is possible since this seal is non rubbing.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Silicon Compounds (AREA)

Claims (7)

1. Un dispositif destiné à être utilisé sur une machine de coulée continue comportant un train de moules (30) ouverts à la partie supérieure et rapprochés les uns des autres montés sur un transporteur sans fin (32), comprenant une plaque de recouvrement (34) disposée à une distance prédéterminée au-dessus de certains desdits moules (30) et ayant une ouverture (42) pour le métal fondu coulé dans chaque moule (30) lorsqu'il passe sous l'ouverture (42) et des moyens (48, 50) pour fournir un gaz non oxydant à l'intérieur des moules (30) sous la plaque de recouvrement, caractérisé en ce que, ladite plaque de recouvrement (24) s'étend sur plusieurs moules (30) disposés avant et plusieurs moules (30) disposés après ladite ouverture (42) et présente une pluralité d'orifices (46) espacées longitudinalement et au-dessus de chaque moule (30) pour fournir un gaz non oxydant à travers la plaque de recouvrement (34) de manière à développer progressivement une atmosphère non oxydante dans les moules (30) lorsqu'ils s'approchent de l'ouverture (42) dans la plaque de recouvrement (34) et pour maintenir ladite atmosphère dans les moules (30) lorsqu'ils dépassent ladite ouverture (42).
2. Dispositif selon la revendication 1, dans lequel ladite atmosphère est une atmosphère inerte.
3. Un dispositif selon la revendication 1, comportant en outre des moyens de fermeture étanches (58) disposés dans les intervalles ménagés entre lesdits moules (30) ouverts ù la partie supérieure de manière à empêcher la fuite excessive de gaz à travers lesdits intervalles.
4. Un dispositif selon la revendication 1, comprenant en outre un poste de coulée du métal pour couler ledit métal fondu dans chacun des moules (30) à travers l'ouverture (42) ménagée dans ladite plaque de recouvrement (34).
5. Un dispositif selon la revendication 4, dans lequel ledit poste de coulée du métal comprend l'extrémité d'un chenal de coulée (36) qui est muni d'une goulotte (38) utilisé pour fournir le métal fondu dans une poche (40) qui pivote de façon intermittente pour verser successivement le métal fondu dans chaque moule (30).
6. Un dispositif selon la revendication 5, comportant en outre des moyens (44) disposés à l'extrémité du chenal de coulée (36) pour recueillir les crasses qui peuvent flotter sur la surface du métal fondu.
7. Un dispositif selon la revendication 5, comportant en outre une enceinte (54) autour de ladite poche (40) ladite goulotte (38) et l'ouverture (42) ménagées dans ladite plaque (34) et des moyens (52) pour fournir un gaz non oxydant à l'intérieur de ladite enceinte (54).
EP19830113078 1983-12-23 1983-12-23 Procédé et installation pour minimiser la formation d'écume pendant la chute libre du métal liquide dans les moules, goulottes ou autres récipients Expired EP0150226B1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU22592/83A AU560253B2 (en) 1983-12-23 1983-12-20 Process and apparatus for minimizing foam formation during free falling of molten metal into moulds, launders or other containers
EP19830113078 EP0150226B1 (fr) 1983-12-23 1983-12-23 Procédé et installation pour minimiser la formation d'écume pendant la chute libre du métal liquide dans les moules, goulottes ou autres récipients
DE8383113078T DE3374279D1 (en) 1983-12-23 1983-12-23 Process and apparatus for minimizing foam formation during free falling of molten metal into moulds, launders or other containers
JP25250083A JPS60145262A (ja) 1983-12-23 1983-12-29 連続鋳造で発泡を最少にするための装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19830113078 EP0150226B1 (fr) 1983-12-23 1983-12-23 Procédé et installation pour minimiser la formation d'écume pendant la chute libre du métal liquide dans les moules, goulottes ou autres récipients

Publications (2)

Publication Number Publication Date
EP0150226A1 EP0150226A1 (fr) 1985-08-07
EP0150226B1 true EP0150226B1 (fr) 1987-11-04

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EP19830113078 Expired EP0150226B1 (fr) 1983-12-23 1983-12-23 Procédé et installation pour minimiser la formation d'écume pendant la chute libre du métal liquide dans les moules, goulottes ou autres récipients

Country Status (4)

Country Link
EP (1) EP0150226B1 (fr)
JP (1) JPS60145262A (fr)
AU (1) AU560253B2 (fr)
DE (1) DE3374279D1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2781395B1 (fr) * 1998-07-27 2000-10-06 Brochot Sa Dispositif pour couler des lingots d'un metal liquide non ferreux, notamment du magnesium liquide, selon de grandes cadences de production sans diminution de la qualite
FR2809643B1 (fr) * 2000-05-31 2002-10-25 Brochot Sa Procede et dispositif pour proteger un metal fondu non ferreux
KR101159949B1 (ko) 2010-02-26 2012-06-25 현대제철 주식회사 주선기의 몰드

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2099208A (en) * 1936-03-02 1937-11-16 William H D Horsfall Apparatus for preventing the oxidation of metals
FR2523005A1 (fr) * 1982-03-08 1983-09-16 Air Liquide Procede et installation de coulee d'un metal non ferreux en lingotiere

Also Published As

Publication number Publication date
JPH0431781B2 (fr) 1992-05-27
JPS60145262A (ja) 1985-07-31
DE3374279D1 (en) 1987-12-10
EP0150226A1 (fr) 1985-08-07
AU560253B2 (en) 1987-04-02
AU2259283A (en) 1985-06-27

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