EP0514246B1 - Steel decarburation process in a vacuum treatment chamber and vacuum treatment chamber therefor - Google Patents

Steel decarburation process in a vacuum treatment chamber and vacuum treatment chamber therefor Download PDF

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Publication number
EP0514246B1
EP0514246B1 EP92401278A EP92401278A EP0514246B1 EP 0514246 B1 EP0514246 B1 EP 0514246B1 EP 92401278 A EP92401278 A EP 92401278A EP 92401278 A EP92401278 A EP 92401278A EP 0514246 B1 EP0514246 B1 EP 0514246B1
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EP
European Patent Office
Prior art keywords
enclosure
steel
treated
metal
vacuum treatment
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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 - Lifetime
Application number
EP92401278A
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German (de)
French (fr)
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EP0514246A1 (en
Inventor
Bernard Bauvois
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Sollac SA
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Sollac SA
Lorraine de Laminage Continu SA SOLLAC
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D25/00—Devices or methods for removing incrustations, e.g. slag, metal deposits, dust; Devices or methods for preventing the adherence of slag
    • F27D25/008—Devices or methods for removing incrustations, e.g. slag, metal deposits, dust; Devices or methods for preventing the adherence of slag using fluids or gases, e.g. blowers, suction units
    • 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

  • the present invention relates to a method for decarburizing steel in a vacuum treatment enclosure and a vacuum treatment enclosure for carrying out the process.
  • Such an enclosure is used to carry out decarburization treatments or dehydrogenation as well as light treatments consisting in producing a steel in which the ranges of the various additives are reduced to such an extent that it is impossible to obtain it directly from the converter.
  • the carbon contained in the metal bath to be treated reacts with the oxygen supplied according to the reaction: C + 1/2 WHERE ⁇ CO Oxygen is brought to the level of the liquid metal bath to be treated by means of a lance which plunges into the treatment enclosure.
  • the disadvantage of this process lies in the fact that the oxygen is blown vertically with respect to the walls of the treatment enclosure, that is to say that it never comes into direct contact with the vertical walls of the enclosure on which metal deposits are formed due to projections from the metal bath during treatment.
  • the deposits on the walls of the enclosure contain a certain amount of carbon depending on the carbon content of the steel during previous treatments.
  • the metal to be treated comes to lick these deposits during its circulation in the intermediate ring of the enclosure, circulation due to the blowing of a neutral gas in one of the plungers with which the lower part is provided. of said enclosure.
  • Part of the deposit is then remelted, which can lead to recarburization of the metal to be treated in the enclosure.
  • the object of the present invention is to provide a process for the decarburization of steel in a vacuum treatment chamber consisting of an upper bell-shaped part, an intermediate ring and a lower part in which the bath is located. of metal to be treated provided with two plungers, which plunge into a steel pocket containing all the metal to be treated, in which oxygen is blown horizontally above the bath of metal to be treated, at the level of the intermediate ring of said enclosure.
  • the present invention also relates to a vacuum steel treatment enclosure for implementing the above process, in which at least two horizontal nozzles are formed in the intermediate ring of said enclosure above the metal bath to process, as claimed in claim 2.
  • the steel decarburization method according to the invention consists in sending an oxygen flow 1 above the metal bath to be treated 2 which is in a vacuum treatment enclosure 3 consisting of an upper part 4 in the form bell, an intermediate ring 5 and a lower part 6 comprising two plungers 7,8 plunging into a steel pocket 9 containing all the steel to be treated 10.
  • the vacuum is produced by means of a vacuum pump device of a known type, not shown, connected to the conduit 13 with which the upper part 4 of the enclosure is provided.
  • the important feature is that the oxygen is sent to the treatment chamber horizontally, that is to say perpendicular to the axis XX of said enclosure.
  • the oxygen licks the bath 2 of metal to be treated contained in the intermediate ring.
  • This oxygen reacts with the carbon contained in the metal according to the reaction: C + 1/2 WHERE ⁇ CO as well as with the CO released during the decarburization reaction, according to the reaction CO + 1/2 O2 ⁇ CO2.
  • the oxygen thus provided allows the implementation of decarburization treatments and of lowering the temperature of the steel before treatment since the addition of oxygen induces an exothermic effect.
  • the advantage of such a method lies in the fact that part of the oxygen blown into the treatment enclosure comes into contact with the vertical walls of the upper part 4 and of the intermediate ring 5 of the enclosure. thus preventing metal projections from the treatment from adhering against said walls.
  • an iron oxide is formed, which falls into the bottom of the lower part of the enclosure, lined with refractory material of the magnesia-chromium type.
  • the refractory material then combines with the iron oxide from unbundling, which leads to a reduction in the melting point of the refractory material, hence an acceleration of its wear by erosion.
  • the present invention also relates to a vacuum treatment enclosure for implementing the method described above.
  • the enclosure 3 is provided in its intermediate ring 5 with at least two horizontal nozzles 11, 12 allowing the blowing of oxygen.
  • the horizontal nozzles 11, 12 are regularly distributed around the periphery of the enclosure 3 and are formed in the middle of the intermediate ring 5, above the metal bath to be treated 2.
  • the intermediate ring 5 is provided with two nozzles 11, 12 facing each other, diametrically opposite, disposed at mid-height of said intermediate ring 5 of the enclosure 3.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Furnace Details (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Furnace Charging Or Discharging (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Control Of Heat Treatment Processes (AREA)

Abstract

Process for the decarburation of steel in a vacuum treatment chamber consisting of a bell-shaped upper part (4), of an intermediate ring (5) and of a lower part (6) in which the bath of metal (2) to be treated is located and which is equipped with two plungers (legs) (7, 8) which are immersed in the ladle (9) with steel containing all the metal (10) to be treated, characterised in that oxygen is blown horizontally over the bath of metal (2) to be treated, at the level of the intermediate ring (5), substantially at its centre. Vacuum steel treatment chamber in which at least two horizontal blast pipes (tuyeres) (11, 12) are provided in the intermediate ring (5) of the said chamber, substantially at its centre. <IMAGE>

Description

La présente invention concerne un procédé de décarburation d'acier dans une enceinte de traitement sous vide et une enceinte de traitement sous vide pour la mise en oeuvre du procédé.The present invention relates to a method for decarburizing steel in a vacuum treatment enclosure and a vacuum treatment enclosure for carrying out the process.

Il est connu p.ex. US-A-4104057 pour effectuer des traitements de l'acier sorti du convertisseur dans lequel il est élaboré, de recourir à une enceinte de traitement sous vide, couramment appelé RHOB (Rheinstahl Heraus Oxygène Blowing).It is known for example US-A-4104057 to carry out treatments of the steel taken out of the converter in which it is produced, to use a vacuum treatment chamber, commonly called RHOB (Rheinstahl Heraus Oxygen Blowing).

Une telle enceinte sert à effectuer des traitements de décarburation ou une déshydrogénation ainsi que des traitements légers consistant à élaborer un acier dont les fourchettes des différents additifs sont réduites à un point tel qu'il est impossible de l'obtenir directement au convertisseur.Such an enclosure is used to carry out decarburization treatments or dehydrogenation as well as light treatments consisting in producing a steel in which the ranges of the various additives are reduced to such an extent that it is impossible to obtain it directly from the converter.

Il est connu d'utiliser une enceinte de traitement sous vide constituée de trois parties :

  • une partie supérieure appelée haut de cuve ayant la forme d'une cloche,
  • un anneau intermédiaire dans lequel se trouve l'acier à traiter,
  • une partie inférieure appelée bas de cuve munie de deux plongeurs, qui plongent dans la poche à acier contenant l'acier à traiter.
It is known to use a vacuum treatment chamber consisting of three parts:
  • an upper part called the top of the tank having the shape of a bell,
  • an intermediate ring in which the steel to be treated is located,
  • a lower part called the bottom of the tank provided with two plungers, which plunge into the steel pocket containing the steel to be treated.

Lors du traitement de décarburation de l'acier, c'est à dire du traitement pour l'amener à une teneur en carbone inférieure à 40 ppm, il est connu d'injecter une certaine quantité d'oxygène au-dessus du bain de métal contenu dans l'enceinte de traitement.During the decarburization treatment of steel, that is to say the treatment to bring it to a carbon content of less than 40 ppm, it is known to inject a certain amount of oxygen above the metal bath contained in the processing enclosure.

Ainsi, le carbone contenu dans le bain de métal à traiter réagit avec l'oxygène apporté selon la réaction:



        C + 1/2 O₂ → CO



   L'oxygène est amené au niveau du bain de métal liquide à traiter au moyen d'une lance qui plonge dans l'enceinte de traitement.Thus, the carbon contained in the metal bath to be treated reacts with the oxygen supplied according to the reaction:



C + 1/2 WHERE → CO



Oxygen is brought to the level of the liquid metal bath to be treated by means of a lance which plunges into the treatment enclosure.

L'inconvénient de ce procédé réside dans le fait que l'oxygène est soufflé verticalement par rapport aux parois de l'enceinte de traitement, c'est à dire qu'il n'entre jamais directement en contact avec les parois verticales de l'enceinte sur lesquelles se forment des dépôts de métal dûs aux projections issues du bain de métal lors du traitement.The disadvantage of this process lies in the fact that the oxygen is blown vertically with respect to the walls of the treatment enclosure, that is to say that it never comes into direct contact with the vertical walls of the enclosure on which metal deposits are formed due to projections from the metal bath during treatment.

Ces dépôts, appelés des loups, s'accumulent dans l'enceinte de traitement, finissent par restreindre de plus en plus la partie libre de l'enceinte et peuvent empêcher le passage de la lance de traitement.These deposits, called wolves, accumulate in the treatment enclosure, eventually restrict more and more the free part of the enclosure and can prevent the passage of the treatment lance.

De plus, les dépôts sur les parois de l'enceinte contiennent une certaine quantité de carbone selon la teneur en carbone de l'acier lors des précédents traitements.In addition, the deposits on the walls of the enclosure contain a certain amount of carbon depending on the carbon content of the steel during previous treatments.

Ainsi, lors des traitements de décarburation, le métal à traiter vient à lécher ces dépôts lors de sa circulation dans l'anneau intermédiaire de l'enceinte, circulation due au soufflage d'un gaz neutre dans un des plongeurs dont est munie la partie basse de ladite enceinte.Thus, during decarburization treatments, the metal to be treated comes to lick these deposits during its circulation in the intermediate ring of the enclosure, circulation due to the blowing of a neutral gas in one of the plungers with which the lower part is provided. of said enclosure.

Une partie du dépôt est alors refondue, ce qui peut entraîner une recarburation du métal à traiter dans l'enceinte.Part of the deposit is then remelted, which can lead to recarburization of the metal to be treated in the enclosure.

Il est donc nécessaire d'évacuer ces dépôts par un traitement dit de déloupage par lequel on souffle de l'oxygène directement sur les loups pour former un oxyde de fer, lequel tombe dans le fond de la cuve.It is therefore necessary to evacuate these deposits by a so-called deloupage treatment by which oxygen is blown directly on the wolves to form an iron oxide, which falls into the bottom of the tank.

Un tel traitement de déloupage est nécessaire environ tous les quinze traitements d'acier dans l'enceinte.Such a rough-out treatment is necessary approximately every fifteen steel treatments in the enclosure.

Un autre inconvénients réside dans l'étanchéité nécessaire au niveau du passage de la lance de traitement dans la partie supérieure de l'enceinte. En effet, l'en-ceinte devant être maintenue sous vide pendant le traitement, l'étanchéité est très complexe à réaliser.Another drawback lies in the sealing required at the level of the passage of the treatment lance in the upper part of the enclosure. Indeed, the enclosure must be kept under vacuum during treatment, sealing is very complex to achieve.

La présente invention a pour but de fournir un procédé de décarburation d'acier dans une enceinte de traitement sous vide constituée d'une partie supérieure en forme de cloche, d'un anneau intermédiaire et d'une partie inférieure dans laquelle se trouve le bain de métal à traiter munie de deux plongeurs, qui plongent dans une poche à acier contenant la totalité du metal à traiter, dans lequel on souffle de l'oxygène horizontalement au-dessus du bain de métal à traiter, au niveau de l'anneau intermédiaire de ladite enceinte.The object of the present invention is to provide a process for the decarburization of steel in a vacuum treatment chamber consisting of an upper bell-shaped part, an intermediate ring and a lower part in which the bath is located. of metal to be treated provided with two plungers, which plunge into a steel pocket containing all the metal to be treated, in which oxygen is blown horizontally above the bath of metal to be treated, at the level of the intermediate ring of said enclosure.

La présente invention concerne également une enceinte de traitement d'acier sous vide pour la mise en oeuvre du procédé ci-dessus, dans laquelle au moins deux tuyères horizontales sont ménagées dans l'anneau intermédiaire de ladite enceinte au-dessus du bain de métal à traiter, comme revendiquée dans la revendication 2.The present invention also relates to a vacuum steel treatment enclosure for implementing the above process, in which at least two horizontal nozzles are formed in the intermediate ring of said enclosure above the metal bath to process, as claimed in claim 2.

Les caractéristiques et avantages apparaîtront au cours de la description qui va suivre, donnée uniquement à titre d'exemple, faite en référence au dessin annexé représentant une vue en coupe d'une enceinte de traitement sous vide selon l'invention.The characteristics and advantages will appear during the description which follows, given solely by way of example, made with reference to the appended drawing representing a sectional view of a vacuum treatment enclosure according to the invention.

Le procédé de décarburation d'acier selon l'invention consiste à envoyer un flux d'oxygène 1 au-dessus du bain de métal à traiter 2 qui se trouve dans une enceinte de traitement sous vide 3 constituée d'une partie supérieure 4 en forme de cloche, d'un anneau intermédiaire 5 et d'une partie inférieure 6 comprenant deux plongeurs 7,8 plongeant dans une poche à acier 9 contenant la totalité de l'acier à traiter 10.The steel decarburization method according to the invention consists in sending an oxygen flow 1 above the metal bath to be treated 2 which is in a vacuum treatment enclosure 3 consisting of an upper part 4 in the form bell, an intermediate ring 5 and a lower part 6 comprising two plungers 7,8 plunging into a steel pocket 9 containing all the steel to be treated 10.

Le vide est réalisé au moyen d'un dispositif de pompe à vide de type connu, non représenté, branché sur le conduit 13 dont est munie la partie supérieure 4 de l'enceinte.The vacuum is produced by means of a vacuum pump device of a known type, not shown, connected to the conduit 13 with which the upper part 4 of the enclosure is provided.

La caractéristique importante réside dans le fait que l'oxygène est envoyé dans l'enceinte de traitement horizontalement, c'est à dire perpendiculairement à l'axe X-X de ladite enceinte.The important feature is that the oxygen is sent to the treatment chamber horizontally, that is to say perpendicular to the axis XX of said enclosure.

Ainsi, l'oxygène lèche le bain 2 de métal à traiter contenu dans l'anneau intermédiaire. Cet oxygène réagit avec le carbone contenu dans le métal selon la réaction :



        C + 1/2 O₂ → CO



   ainsi qu'avec le CO dégagé pendant la réaction de décarburation, selon la réaction CO + 1/2 O₂ → CO₂. L'oxygène ainsi apporté permet la réalisation des traitements de décarburation et de baisser la température de l'acier avant traitement puisque l'apport de l'oxygène induit un effet exothermique.Thus, the oxygen licks the bath 2 of metal to be treated contained in the intermediate ring. This oxygen reacts with the carbon contained in the metal according to the reaction:



C + 1/2 WHERE → CO



as well as with the CO released during the decarburization reaction, according to the reaction CO + 1/2 O₂ → CO₂. The oxygen thus provided allows the implementation of decarburization treatments and of lowering the temperature of the steel before treatment since the addition of oxygen induces an exothermic effect.

L'avantage d'un tel procédé réside dans le fait qu'une partie de l'oxygène soufflé dans l'enceinte de traitement vient en contact avec les parois verticales de la partie supérieure 4 et de l'anneau intermédiaire 5 de l'enceinte empêchant ainsi les projections de métal issues du traitement d'adhérer contre lesdites parois.The advantage of such a method lies in the fact that part of the oxygen blown into the treatment enclosure comes into contact with the vertical walls of the upper part 4 and of the intermediate ring 5 of the enclosure. thus preventing metal projections from the treatment from adhering against said walls.

La fréquence des traitements nécessaires pour le déloupage est réduite, ce qui entraîne ainsi une durée de vie plus longue du fond de la partie inférieure 6 de l'enceinte.The frequency of treatments necessary for unbundling is reduced, which thus results in a longer lifespan of the bottom of the lower part 6 of the enclosure.

En effet, lors du déloupage, il se forme un oxyde de fer, lequel tombe dans le fond de la partie inférieure de l'enceinte, tapissé de matériau réfractaire du type magnésie-chrome.In fact, during unbundling, an iron oxide is formed, which falls into the bottom of the lower part of the enclosure, lined with refractory material of the magnesia-chromium type.

Le matériau réfractaire se combine alors avec l'oxyde de fer issu de déloupage, ce qui entraîne une diminution du point de fusion du matériau réfractaire d'où une accélération de son usure par érosion.The refractory material then combines with the iron oxide from unbundling, which leads to a reduction in the melting point of the refractory material, hence an acceleration of its wear by erosion.

La présente invention concerne également une enceinte de traitement sous vide pour la mise en oeuvre du procédé décrit ci-dessus.The present invention also relates to a vacuum treatment enclosure for implementing the method described above.

L'enceinte 3 est munie dans son anneau intermédiaire 5 d'au moins deux tuyères 11, 12 horizontales permettant le soufflage d'oxygène.The enclosure 3 is provided in its intermediate ring 5 with at least two horizontal nozzles 11, 12 allowing the blowing of oxygen.

Les tuyères horizontales 11,12 sont régulièrement réparties à la périphérie de l'enceinte 3 et sont ménagées au milieu de l'anneau intermédiaire 5, au-dessus du bain de métal à traiter 2.The horizontal nozzles 11, 12 are regularly distributed around the periphery of the enclosure 3 and are formed in the middle of the intermediate ring 5, above the metal bath to be treated 2.

Dans l'exemple de réalisation représenté, l'anneau intermédiaire 5 est muni de deux tuyères 11, 12 en vis à vis, diamétralement opposées, disposées à mihauteur dudit anneau intermédiaire 5 de l'enceinte 3.In the embodiment shown, the intermediate ring 5 is provided with two nozzles 11, 12 facing each other, diametrically opposite, disposed at mid-height of said intermediate ring 5 of the enclosure 3.

Claims (4)

  1. Process for the decarburization of steel in a vacuum treatment enclosure consisting of a bell-shaped upper part (4), an intermediate ring (5) and a lower part (6) which contains the bath of metal to be treated (2) and which is equipped with two dippers (7, 8) dipping into the steel ladle (9) containing all the metal which is to be treated (10), in which process oxygen is blown into the treatment enclosure, characterised in that the oxygen is blown in horizontally above the bath of metal to be treated (2), level with the intermediate ring (5) of said enclosure.
  2. Vacuum treatment enclosure for carrying out the process according to claim 1, consisting of a bell-shaped upper part (4), an intermediate ring (5) and a lower part (6) which contains the bath of metal to be treated (2) and which is equipped with two dippers (7, 8) dipping into the steel ladle (9) containing all the metal to be treated (10), characterised in that at least two horizontal blowers (11, 12) are provided in the intermediate ring (5) of said enclosure (3) above the bath of metal to be treated (2).
  3. Vacuum treatment enclosure according to claim 2, characterised in that the horizontal blowers (11, 12) are uniformly distributed around the periphery of the enclosure.
  4. Treatment enclosure according to claim 2, characterised in that the blowers (11, 12) are provided in the middle of the intermediate ring (58) of said enclosure (3).
EP92401278A 1991-05-13 1992-05-07 Steel decarburation process in a vacuum treatment chamber and vacuum treatment chamber therefor Expired - Lifetime EP0514246B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR919105753A FR2676458B1 (en) 1991-05-13 1991-05-13 PROCESS FOR DECARBURIZING STEEL IN A VACUUM PROCESSING ENCLOSURE AND VACUUM PROCESSING ENCLOSURE FOR IMPLEMENTING THE PROCESS.
FR9105753 1991-05-13

Publications (2)

Publication Number Publication Date
EP0514246A1 EP0514246A1 (en) 1992-11-19
EP0514246B1 true EP0514246B1 (en) 1995-08-02

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EP92401278A Expired - Lifetime EP0514246B1 (en) 1991-05-13 1992-05-07 Steel decarburation process in a vacuum treatment chamber and vacuum treatment chamber therefor

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US (1) US5332417A (en)
EP (1) EP0514246B1 (en)
KR (1) KR100232912B1 (en)
AT (1) ATE125933T1 (en)
CA (1) CA2087179C (en)
DE (1) DE69203788T2 (en)
ES (1) ES2076705T3 (en)
FR (1) FR2676458B1 (en)
TW (1) TW202482B (en)
WO (1) WO1992020986A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5603749A (en) * 1995-03-07 1997-02-18 Bethlehem Steel Corporation Apparatus and method for vacuum treating molten steel
CN111518992B (en) * 2020-05-08 2022-02-08 赵元庆 Tank type single-nozzle refining furnace and vacuum refining method

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4104057A (en) * 1972-06-10 1978-08-01 Hermann Maas Method for making low carbon high chromium alloyed steels
US4071356A (en) * 1976-11-24 1978-01-31 Nippon Steel Corporation Method for refining a molten steel in vacuum
US4105057A (en) * 1977-09-23 1978-08-08 Amity Leather Products Company Flexible receptacle with credit card holder
FR2542014B1 (en) * 1983-03-02 1985-06-21 Solmer DEVICE FOR CLEARING STEEL CONVERTER SPOUT
EP0328851A1 (en) * 1988-02-16 1989-08-23 Acciaierie E Ferriere Lombarde Falck S.P.A. An apparatus for decarbonizing steels directly in the ladle
JPH01283316A (en) * 1988-05-11 1989-11-14 Nkk Corp Method of maintaining degassing vessel

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DE69203788T2 (en) 1996-01-11
KR930701721A (en) 1993-06-12
ES2076705T3 (en) 1995-11-01
WO1992020986A1 (en) 1992-11-26
FR2676458B1 (en) 1994-03-04
DE69203788D1 (en) 1995-09-07
ATE125933T1 (en) 1995-08-15
EP0514246A1 (en) 1992-11-19
KR100232912B1 (en) 1999-12-01
CA2087179A1 (en) 1992-11-14
FR2676458A1 (en) 1992-11-20
CA2087179C (en) 2002-07-02
TW202482B (en) 1993-03-21
US5332417A (en) 1994-07-26

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