EP0352356B1 - Process and relevant equipment for carrying out the continuous casting of steel in the complete absence of oxidating agents - Google Patents

Process and relevant equipment for carrying out the continuous casting of steel in the complete absence of oxidating agents Download PDF

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Publication number
EP0352356B1
EP0352356B1 EP88112281A EP88112281A EP0352356B1 EP 0352356 B1 EP0352356 B1 EP 0352356B1 EP 88112281 A EP88112281 A EP 88112281A EP 88112281 A EP88112281 A EP 88112281A EP 0352356 B1 EP0352356 B1 EP 0352356B1
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EP
European Patent Office
Prior art keywords
casting
chamber
steel
liquid steel
atmosphere
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
EP88112281A
Other languages
German (de)
English (en)
French (fr)
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EP0352356A1 (en
Inventor
Lorenzo Ferrari
Mario Giavani
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.)
KINGLOR - Ltd
Original Assignee
KINGLOR - Ltd
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
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Priority to IT20766/88A priority Critical patent/IT1218007B/it
Application filed by KINGLOR - Ltd filed Critical KINGLOR - Ltd
Priority to EP88112281A priority patent/EP0352356B1/en
Priority to DE8888112281T priority patent/DE3868061D1/de
Priority to BR898902402A priority patent/BR8902402A/pt
Priority to JP1135693A priority patent/JPH0220641A/ja
Publication of EP0352356A1 publication Critical patent/EP0352356A1/en
Application granted granted Critical
Publication of EP0352356B1 publication Critical patent/EP0352356B1/en
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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
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D45/00—Equipment for casting, not otherwise provided for
    • B22D45/005—Evacuation of fumes, dust or waste gases during manipulations in the foundry

Definitions

  • the object of the present invention is a process for carrying out the continuous casting of steel under such operating conditions, as to prevent the oxidation of liquid steel during all casting steps.
  • a facility for continuous casting comprises a tundish, or distributor body, internally lined with a refractory material, which receives the liquid metal from a overhanging casting ladle, one or more ingot moulds or crystallizers, usually of copper, constantly cooled by water circulation, wherein a partial and quick solidification of the metal occurs, and, on line with said ingot moulds, cooling areas wherein the complete solification takes place by means of water jets.
  • the bar leaving said cooling areas is made advance by means of withdrawal rolls and is then cut to the desired lengths.
  • liquid steel has to be deoxidated by means of the addition of deoxidizers based on aluminum, silicon, or the like.
  • ceramic shrouds are used and coating products or powders, similar to low-melting glasses in the molten state, are provided on all the exposed steel surfaces during the casting, and, more precisely on the exposed steel surface in the ingot moulds, and on the exposed steel surface inside the tundish.
  • the steel cast from the ladle to the tundish and the steel cast from the tundish to the ingot mould is usually enclosed inside shrouds of ceramic material or the like, in order to prevent steel from getting oxidized during casting. It is known that such shrouds are affected by the drawback of being fragile, expensive and of requesting a replacement for each casting. Furthermore the contact between the ceramic shroud and the nozzle is poor and often there is air suction owing to Venturi effect.
  • the steel is killed by means of aluminum, which, when comes into contact with atmospheric oxygen, forms aluminum oxide (Al2O3); this latter, by being solid at the temperature of liquid steel, and insoluble in this latter, causes the formation of crusts and agglomerates which clog the ducts of the casting facility, and, in particular, the nozzles positioned at the bottom of the tundish, as well as said ceramic shrouds.
  • Al2O3 aluminum oxide
  • DE 2839870 (BRITISH STEEL) relates to a method and an apparatus for use in pouring molten steel to provide a protective gaseous shroud to limit the access of atmospheric oxygen to the falling metal stream and to the impact zone of the stream with the metal pool or receiving equipment beneath and to delay the penetration of atmospheric oxygen to the liquid metal surface.
  • the apparatus comprises means for providing inert gas in the form of an annular duct encircling the nozzle from which the metal stream is poured, dimensioned and apertured to project the gas inwardly around the nozzle as to provide a zone of gas surrounding the nozzle exit and moving downwardly around the stream.
  • the source of inert gas is exposed near to the falling metal stream and a considerable amount of metal splashing may be expected to result in a significant build-up of frozen metal over the gas source which will adversely affect the ability of the source to provide a low turbulence zone of gas around the nozzle exit.
  • the outermost surface of the gas-dispensing element is a removable part which can be replaced by a clean surface after a period of use.
  • EP 0005820 (CONCAST AG) relates to a process for continuous casting of a molten metal, in which the metal is poured from a tundish into a mold swinging with a closed chamber filled with inert gas under pressure above the surface of the molten metal contained in the mold.
  • inert gas is continuously supplied so that the gas is discharged to the atmosphere rising upwardly through the metal in the form of bubbles in countercurrent in respect of the metal flowing downwardly into the pouring tube.
  • an electromagnetic field is generated by means of induction coils positioned around the mold.
  • a purpose of the present invention is to realize a process for the continuous casting of steel , so conceived as to obviate the drawbacks caused by the fast oxidation of steel in the presence of air and, in particular, of the aluminum for obtaining killed steels, without altering the normal operating conditions of continuous casting by one or more casting lines, and operating in free stream.
  • Another purpose of the invention is to provide a process for the continuous casting of steel which can be wholly carried out in the complete absence of air oxygen, with evident advantages as regards the quality of the solidified steel, the safety of the casting facility and the saving in costs consequent to the elimination of the coating powders and of the shrouds of ceramic material, or the like.
  • a further purpose of the present invention is to provide art equipment for carrying out tie above-said process of continuous casting, which is structurally simple, highly reliable, and can be used both on already existing facilities, and on newly-built facilities.
  • an equipment which is constituted by an air-tight chamber, with at least a portion of the walls of said air-tight chamber being constituted by a transparent material, so designed as to enclose all those portions of the casting facility in which liquid steel is in contact with atmosphere, means being provided for maintaining inside said chamber an atmosphere of nitrogen, or of another inert, non-toxic gas, such as carbon dioxide, argon, and their mixtures, under a slight overpressure and free from oxygen, as well as closed-loop conditioning means being provided, in order to remove from said inert gas the heat, the fumes and the vapours released during the casting process, with said chamber means of connection with the external atmosphere being furthermore associated, in order to allow attending personnel, equipped with a breathing mask, to enter the chamber in order to control the casting process or to control the process by means of tight gloves, handling means and the like.
  • said air-tight chamber is preferably provided with at least one wall fully made from a transparent material, and with at least one other wall made from a fast-breakage material, for emergency cases.
  • the air-tightness between the ladle and the casting machine and the walls of the chamber can be preferably achieved by means of suitable water-sealed, sand-sealed labyrinth seals, or the like.
  • a facility for the continuous casting of steel is constituted by a casting ladle 1 containing liquid steel 2 produced, for example,by an electric-furnace.
  • Liquid steel 4 flows by gravity through a gate valve 3 into a tundish, or distributor, 5, wherein steel is maintained at a constant level. From the tundish 5 steel flows, through one or more nozzles 6, into a same number of ingot moulds 7.
  • the switch 8 of the liquid steel cast 4a which feeds each moulding line, performs also the function of tightly sealing the opening 7a of the ingot mould 7 in the presence of first-line leakages, and of preventing that, in case the casting is discontinued, from said opening the inert gas may escape, which is contained inside the chamber.
  • the crystallizer generally supplied with a vertical oscillatory movement, is normally made of copper, and is fitted with means for a vigorous water-cooling, not depicted in the figure; inside the crystallizer, liquid steel undergoes a partial and fast solidification.
  • the reference numeral 9 the portion of steel solidified inside the crystallizer, and by the reference numeral 10, the inner, still liquid, conical portion, of the bar, are indicated.
  • the bar 11 When leaving the crystallizer, the bar 11 runs through cooling means (not depicted in the figure), which complete the solidification thereof.
  • the bar (or the bars, in case with the tundish a plurality of crystallizers are associated) runs downwards with a speed controlled by the withdrawal rolls 16.
  • the present invention provides an equipment, which is constituted by an air-tight chamber 14, which encloses all those areas of the facility, in which high-temperature, liquid steel is in contact with air, i.e., all the equipment pieces which are comprised between the bottom of the ladle 1 and the basis of the moulds 7.
  • the air-tightness between the ladle 1 and the basis of the mould 7 and the walls of the chamber 14 is achieved by means of labyrinth sealing means 19.
  • an atmosphere is maintained, which is constituted by nitrogen or carbon dioxide or argon, or by a mixture of said gases, or of similar gases, free from oxygen, under a slight over-pressure, which thus prevents steel of exposed steel surfaces 12 and 13, from being oxidized.
  • a closed-loop conditioning system (not shown in figure) is furthermore associated, which is fitted with suitable sucking and circulation means, the function of which is of removing the heat, the fumes and vapours generated during the casting step.
  • check and control means are associated, as well as sensors are provided (not depicted in the figure), such as to render fully automated the operation of the casting.
  • said chamber is fitted with at least one flexible hose 17, or the like, which connects the external environment with the interior of the same chamber, and which allows the attending personnel to enter the same chamber, by using, e.g., a protection mask, or a tight suit, 18, connected with the external atmosphere, or with other ventilation means, so that the necessary and suitable switching and checking actions can be carried out.
  • At least one wall of the chamber is made from a transparent material, and at least a further wall, or the entrance door, are made from a fast-breakage material, in order to allow any emergency interventions to be performed.
  • the walls of said chamber 14 are made from a material particularly resistant to heat and to the possible drops of liquid steel.
  • the use of the covering powders is eliminated, and the metal portion of the tundish, which is generally lined with a refractory material, is also prevented from being perforated, in case the refractory is broken or cracked; in fact, owing to the contact of high-temperature liquid steel - seeped through the refractory - with the metal wall of the tundish, this latter gets overheated, and would rapidly react with air oxygen - if present -, melting, and consequently causing liquid steel to escape.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Continuous Casting (AREA)
EP88112281A 1988-05-27 1988-07-29 Process and relevant equipment for carrying out the continuous casting of steel in the complete absence of oxidating agents Expired EP0352356B1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
IT20766/88A IT1218007B (it) 1988-05-27 1988-05-27 Procedimento per la formatura automatica di un tubo metallico continuo riempito con materiali in polvere,sua introduzione diretta nel metallo liquido e relativa apparecchiatura
EP88112281A EP0352356B1 (en) 1988-05-27 1988-07-29 Process and relevant equipment for carrying out the continuous casting of steel in the complete absence of oxidating agents
DE8888112281T DE3868061D1 (de) 1988-05-27 1988-07-29 Verfahren und zweckdienliche einrichtung fuer die durchfuehrung von stahlstrangguss bei vollstaendiger abwesenheit von oxydierenden mitteln.
BR898902402A BR8902402A (pt) 1988-05-27 1989-05-26 Processo para formacao continua e automatica de um tubo metalico continuo enchido com materiais em forma de po para o tratamento metalurgico de metais em fusao dentro da cacamba de corrida,e para carregar o mesmo no metal em fusao contido na cacamba
JP1135693A JPH0220641A (ja) 1988-05-27 1989-05-29 金属チューブの形成及び注入方法及びその装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT20766/88A IT1218007B (it) 1988-05-27 1988-05-27 Procedimento per la formatura automatica di un tubo metallico continuo riempito con materiali in polvere,sua introduzione diretta nel metallo liquido e relativa apparecchiatura
EP88112281A EP0352356B1 (en) 1988-05-27 1988-07-29 Process and relevant equipment for carrying out the continuous casting of steel in the complete absence of oxidating agents

Publications (2)

Publication Number Publication Date
EP0352356A1 EP0352356A1 (en) 1990-01-31
EP0352356B1 true EP0352356B1 (en) 1992-01-22

Family

ID=39689257

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88112281A Expired EP0352356B1 (en) 1988-05-27 1988-07-29 Process and relevant equipment for carrying out the continuous casting of steel in the complete absence of oxidating agents

Country Status (5)

Country Link
EP (1) EP0352356B1 (it)
JP (1) JPH0220641A (it)
BR (1) BR8902402A (it)
DE (1) DE3868061D1 (it)
IT (1) IT1218007B (it)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10112621A1 (de) * 2001-03-14 2002-09-19 Km Europa Metal Ag Anordnung zum Abgießen einer aus einer Kupferlegierung bestehenden Gießschmelze
JP4165147B2 (ja) 2002-08-12 2008-10-15 株式会社Ｉｈｉ 双ロール鋳造機
CN101658920A (zh) * 2009-10-10 2010-03-03 山东泰山钢铁集团有限公司 一种防止碳钢精密铸件浇注时氧化的方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT340620B (de) * 1975-02-25 1977-12-27 Voest Ag Einrichtung zur behandlung von metallschmelzen wahrend des stranggiessens mit spulgas
ES473273A1 (es) 1977-09-13 1979-10-16 British Steel Corp Un aparato y un metodo para proteger una corriente de metal contra la atmosfera circundante
CH628543A5 (de) 1978-06-01 1982-03-15 Concast Ag Verfahren und vorrichtung zum stranggiessen von metall in ein- oder mehrstranganlagen.

Also Published As

Publication number Publication date
BR8902402A (pt) 1990-01-16
DE3868061D1 (de) 1992-03-05
IT8820766A0 (it) 1988-05-27
EP0352356A1 (en) 1990-01-31
JPH0220641A (ja) 1990-01-24
IT1218007B (it) 1990-03-30

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