EP0536185B1 - Liquid steel bath reheating method - Google Patents
Liquid steel bath reheating method Download PDFInfo
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- EP0536185B1 EP0536185B1 EP91910980A EP91910980A EP0536185B1 EP 0536185 B1 EP0536185 B1 EP 0536185B1 EP 91910980 A EP91910980 A EP 91910980A EP 91910980 A EP91910980 A EP 91910980A EP 0536185 B1 EP0536185 B1 EP 0536185B1
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- European Patent Office
- Prior art keywords
- injection
- bath
- oxidizing gas
- gas
- fact
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 39
- 239000010959 steel Substances 0.000 title claims abstract description 39
- 239000007788 liquid Substances 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000003303 reheating Methods 0.000 title abstract description 5
- 230000001590 oxidative effect Effects 0.000 claims abstract description 40
- 238000002347 injection Methods 0.000 claims abstract description 39
- 239000007924 injection Substances 0.000 claims abstract description 39
- 229910052751 metal Inorganic materials 0.000 claims abstract description 15
- 239000002184 metal Substances 0.000 claims abstract description 15
- 238000002156 mixing Methods 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000004411 aluminium Substances 0.000 claims 1
- 239000007789 gas Substances 0.000 abstract description 57
- 239000000446 fuel Substances 0.000 abstract description 24
- 238000003756 stirring Methods 0.000 description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 15
- 229910052760 oxygen Inorganic materials 0.000 description 15
- 239000001301 oxygen Substances 0.000 description 15
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000009826 distribution Methods 0.000 description 7
- 229910052786 argon Inorganic materials 0.000 description 5
- 239000002893 slag Substances 0.000 description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 239000012535 impurity Substances 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 239000007800 oxidant agent Substances 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 239000003517 fume Substances 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
Images
Classifications
-
- 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
- C21C7/005—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using exothermic reaction compositions
Definitions
- the present invention relates to a method for heating a bath of liquid steel contained in a metallurgical vessel.
- Such a bath can be heated with a flame, or electrically.
- a single consumable lance injects, under the liquid steel, oxidizing agents, in particular gaseous oxygen, and an inert gas, which are introduced, separately or as a mixture, at a depth of 15 to 40% of the bath, by a plurality of parallel channels.
- oxidizing agents in particular gaseous oxygen, and an inert gas, which are introduced, separately or as a mixture, at a depth of 15 to 40% of the bath, by a plurality of parallel channels.
- Aluminum is also introduced into the bath as close as possible to the oxygen injection point.
- Also known from document EP-A-0352254 is a device for reheating a bath of liquid steel during filling from the top of a metallurgical container. This bath is covered with a slag rich in iron oxide. During the filling of the bag, a metal or an alloy capable of reacting with slag iron oxide and the bath oxides is injected through its bottom, on the one hand, and an inert gas on the other hand. In addition, the reheating is completed by the presence of a burner at the level of the pocket cover.
- Such a device does not provide for the direct injection of oxidizing gas into the steel bath and is not intended to be used to heat the steel contained in an already filled pocket.
- Document JP-A-5989708 describes a process by which a current is induced in a bath of liquid steel. An oxygen lance is introduced into the bath, and a stirring gas is injected into the bottom of the container by a porous brick located just in front of the oxygen lance. We observe uncontrollable turbulence in the steel, an imperfect distribution of the fuel and therefore a relatively low efficiency.
- Patent CH-A-486935 discloses a pocket containing liquid steel above the surface of which is placed a bell surrounding a lance non-consumable which projects gaseous oxygen therein in a determined quantity.
- a metallic fuel is introduced simultaneously, also in a determined quantity, and the exothermic reaction takes place above the bath.
- an inert gas is injected by another lance, introduced obliquely to a depth of about 50% of the steel bath, and causes movements therein.
- a device as described above has a low thermal efficiency and even if it avoids the problems of lance wear, it requires a lot of maintenance, does not ensure a perfect distribution of the temperature in the the entire bath of liquid steel and requires perfect mastery of a complex and expensive technology and process.
- the object of the present invention is to provide a perfectly controlled metallothermic process for efficiently heating a bath of liquid steel already contained in a pocket.
- Another object of the invention is to provide a process in which the yield relating to the consumption of oxygen and of combustible metal is constant and better than in the processes known from the prior art.
- a further object of the invention is to provide a method making it possible to obtain a very homogeneous distribution of the metallic fuel and thereby of the temperature in the bath of liquid steel, and this in a satisfactory period of time, and using simple and economical means.
- Another object of the invention is to provide a method by which good cleanliness of the liquid steel bath can be easily obtained.
- a final object of the invention is to provide a process by which there is practically no release of fumes above the bath and which does not add pollution to the environment.
- the subject of the invention is a method for metallothermic heating of a bath of liquid steel contained in a metallurgical container, into which a metallic fuel is introduced and under the surface of which an oxidizing gas and a stirring gas are injected into which creates in the bath a current resulting from the injection of a stirring gas, by a means distinct from the means for injecting the oxidizing gas, and in which the metallic fuel is introduced into the current, so that it is brought into contact with the oxidizing gas, this process being characterized in that the axes of injection of the oxidizing gas and of the stirring gas are offset with respect to each other, and in that the injection of the gas stirring generates an ascending current in the liquid steel, this current becoming descending at the place of injection of the oxidizing gas.
- a controllable current is created in the bath resulting from the injection of a stirring gas, by a means distinct from the means for injecting the oxidizing gas, and the metallic fuel is introduced into this current, so that it is brought into contact with the oxidizing gas.
- the axes of injection of the stirring gas and the oxidizing gas offset from one another may for example be parallel to each other. They are also in this case perpendicular to the surface of the steel bath.
- This procedure in fact makes it possible to distribute the fuel more regularly, to improve the settling of the products of the reaction and to standardize the temperature of the liquid steel bath, by promoting the exothermic reaction throughout the bath.
- the streams of liquid steel thus generated entail impurities constituted in particular by the reaction products which can cause inclusions towards the upper part of the bath, more particularly the slag.
- the relative positions of the axes of injection of the stirring gas and of the oxidizing gas and that of the metallic fuel can be defined as follows: the injection of the stirring gas generates a theoretical cone metal suction pipe, the top of which is at the injection site. Its generator extends the injection axis; its taper is a function of the gas flow rate, and the height of liquid steel in the metallurgical vessel. This cone has a base defining on the liquid steel surface a theoretical circle, the dimensions of which can be calculated.
- the oxidizing gas reacts with the fuel in a substantially spherical area.
- a corresponding second theoretical circle can be defined on the surface of the steel bath, the center of which is the axis of injection of oxidizing gas, and the dimensions of which can be calculated.
- the two theoretical circles generated respectively by the injection of the stirring gas and by the injection of the oxidizing gas partially overlap by defining between them an intersection zone, into which the metallic fuel, preferably aluminum under wire form.
- the metallic fuel is preferably introduced into the intersection zone, at a point of intersection between the circumferences of the two theoretical circles.
- the means for injecting oxidizing gas is preferably a consumable lance which can be plunged to a lesser depth compared to the state of the art. Particularly advantageous results are obtained if the depth of the lance is maintained between 0 and 15% of the height of the bath of liquid steel contained in the metallurgical vessel, preferably between 3 and 30 cm.
- the oxidizing gas is generally oxygen and the stirring gas is preferably a neutral gas, generally argon.
- the stirring gas is injected at a depth greater than 60% of the height of the bath, and preferably as close as possible to the bottom of the pocket.
- a porous element placed in the bottom coating of the metallurgical container.
- a second lance immersed at great depth preferably greater than 60% of the height of the bath.
- Figures 1 and 2 show a metallurgical container such as for example a ladle 1, coated with a refractory material 3 and having, at its lower part, a tap hole 5 provided with equipment 7 for opening and closing said hole.
- a stirring gas in this case argon, is injected by a porous element 9 placed in the bottom of the ladle 1.
- the injection axis 91 constitutes the axis of a suction cone of metal 92.
- the argon rises to the surface of the bath 11 and then escapes freely into the atmosphere.
- the base of the cone 92 is located at the level of the surface of the bath. It has the shape of a circle 93 and is represented by a solid line in FIG. 2.
- An aluminum wire 13 serving as metallic fuel is introduced into the bath 11.
- This fuel reacts with oxygen which is then injected into the bath.
- the reaction is highly exothermic and will advantageously be used to heat the bath efficiently and quickly and by obtaining an excellent distribution of the temperature, thanks to the relative arrangement of the various elements.
- the oxygen is injected by a consumable lance 15, made of refractory material, which plunges into the bath of liquid steel 11 over a depth which can range from 0 to 15% of the height of the bath, considered under the slag zone 12 present at the surface.
- Maintaining the immersion depth of the lance 15 is advantageously controlled by means known per se, and adapted as a function of the average wear speed of the lance.
- a theoretical axis of injection of the oxidizing gas 151 can be defined in the liquid steel bath, this axis being located in the extension of the consumable lance 15.
- the stirring gas drives the aluminum in the downward movement which it imposes on the liquid steel near the surface of the bath 11, and brings it near the end of the lance. 15 injection of the oxidizing gas. It reacts exothermically with the latter.
- the reaction takes place in a substantially spherical zone 152 whose dimensions depend on the flow rate of the oxidizing gas, on its purity and on the local content of combustible metal.
- FIG. 1 shows a reaction zone 152 which has a substantially ellipsoidal shape.
- the ellipsoidal character is more or less marked depending on the importance of the flow rate of the oxidizing gas.
- the fuel and the oxidizing gas are introduced with a slight time difference, which is taken into account in the calculation.
- a second theoretical circle 153 whose center corresponds to the axis of injection of the oxidizing gas and whose diameter is that of the sphere.
- Such a circle is shown in dotted lines in fig. 2. It can also be defined in the case of an ellipsoidal reaction zone.
- the diameter of the circle 93 defined by the base of the cone generated by the stirring gas can be determined with precision. Studies give a value of about 10 ° for the half angle at the top of the cone 92.
- the circles 93 and 153 define between them an intersection zone 915 into which the aluminum wire 13 is introduced; preferably at one of the points of intersection between the two circumferences. This arrangement makes it possible to obtain a maximum yield and an excellent distribution of the temperature in the bath.
- Fig.3 illustrates the course of a heating operation of a bath of liquid steel according to the method of the invention.
- the graph shows the evolution over time of the flows of the mixing gas, in this case argon (Ar), of the fuel in this case of aluminum (Al) and of the oxidizing gas, in this case oxygen (O2).
- the injection of the stirring gas is started, then the metal fuel wire is introduced and finally the oxygen injection is started.
- the downdraft induced by the stirring gas perpetually brings new quantities of aluminum-charged liquid steel near the injection point of the oxidizing gas, which reacts with oxygen.
- a rotating movement is generated in the bath and in particular allows the migration of impurities towards the slag.
- the injections are continued until the desired temperature is obtained. Once this temperature has been reached, the oxygen lance is removed while maintaining a slight flow rate until this lance is removed from the bath, thus avoiding blockage of the insufflation duct.
- the mixing with neutral gas is also maintained for a certain time so as to favor removal of impurities resulting from the reaction as well as debris due to erosion of the lance.
- an additional lance for injecting stirring gas can be provided instead of or in addition to the porous element 15.
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Gas Burners (AREA)
Abstract
Description
La présente invention est relative à un procédé pour réchauffer un bain d'acier liquide contenu dans un récipient métallurgique.The present invention relates to a method for heating a bath of liquid steel contained in a metallurgical vessel.
En cas de discontinuité accidentelle dans le déroulement du processus métallurgique, entre l'élaboration de l'acier au convertisseur et l'opération de solidification, le bain d'acier liquide contenu dans un récipient métallurgique se refroidit et il est classique de devoir le réchauffer pour permettre la poursuite ultérieure normale du processus.In the event of an accidental discontinuity in the progress of the metallurgical process, between the production of the steel in the converter and the solidification operation, the bath of liquid steel contained in a metallurgical container cools and it is conventional to have to reheat it. to allow normal further processing.
Un tel bain peut être réchauffé à la flamme, ou électriquement.Such a bath can be heated with a flame, or electrically.
On connaît encore divers procédés faisant appel à la métallothermie, selon lesquels un combustible métallique, par exemple de l'aluminium, est introduit dans le bain d'acier liquide et mis en contact avec un agent oxydant, par exemple de l'oxygène gazeux. La réaction entre le métal combustible et l'oxydant est exothermique, et la chaleur obtenue est utilisée pour le réchauffage du bain.There are also known various processes using metallothermy, according to which a metallic fuel, for example aluminum, is introduced into the bath of liquid steel and brought into contact with an oxidizing agent, for example oxygen gas. The reaction between the combustible metal and the oxidant is exothermic, and the heat obtained is used for heating the bath.
On connaît, par le brevet-US-A-4 761 178 et son équivalent, la demande WO 89/01984, un récipient contenant un bain d'acier liquide qu'on réchauffe en utilisant un procédé d'aluminothermie, et en injectant un gaz de brassage.We know, from patent-US-A-4,761,178 and its equivalent, application WO 89/01984, a container containing a bath of liquid steel which is reheated using an aluminothermic process, and by injecting a brewing gas.
Une lance consommable unique injecte, sous l'acier liquide, des agents oxydants, notamment de l'oxygène gazeux, et un gaz inerte, qui sont introduits, séparément ou en mélange, à une profondeur de 15 à 40 % du bain, par une pluralité de canaux parallèles. De l'aluminium est par ailleurs introduit dans le bain aussi près que possible du point d'injection d'oxygène.A single consumable lance injects, under the liquid steel, oxidizing agents, in particular gaseous oxygen, and an inert gas, which are introduced, separately or as a mixture, at a depth of 15 to 40% of the bath, by a plurality of parallel channels. Aluminum is also introduced into the bath as close as possible to the oxygen injection point.
On a constaté que l'introduction d'une telle lance à cette profondeur en causait une usure importante. De plus, le réchauffement de la partie inférieure du bain n'est pas particulièrement efficace, car les mouvements y sont peu importants, et l'acier liquide n'est homogène ni en température ni en propreté inclusionnaire.It was found that the introduction of such a lance at this depth caused significant wear. In addition, the heating of the lower part of the bath is not particularly effective, because the movements are small, and the liquid steel is homogeneous neither in temperature nor in inclusive cleanliness.
On connaît encore, par le document EP-A-0352254, un dispositif pour le réchauffage d'un bain d'acier liquide lors du remplissage par le haut d'un récipient métallurgique. Ce bain est recouvert d'un laitier riche en oxyde de fer. Pendant le remplissage de la poche, on injecte par son fond d'une part un métal ou un alliage susceptible de réagir avec l'oxyde de fer du laitier et les oxydes du bain, et d'autre part un gaz inerte.
En outre, le réchauffage est complété par la présence d'un brûleur au niveau du couvercle de la poche.Also known from document EP-A-0352254 is a device for reheating a bath of liquid steel during filling from the top of a metallurgical container. This bath is covered with a slag rich in iron oxide. During the filling of the bag, a metal or an alloy capable of reacting with slag iron oxide and the bath oxides is injected through its bottom, on the one hand, and an inert gas on the other hand.
In addition, the reheating is completed by the presence of a burner at the level of the pocket cover.
Un tel dispositif ne prévoit par l'injection directe de gaz oxydant dans le bain d'acier et n'est pas destiné à être utilisé pour réchauffer l'acier contenu dans une poche déjà remplie.Such a device does not provide for the direct injection of oxidizing gas into the steel bath and is not intended to be used to heat the steel contained in an already filled pocket.
Le document JP-A-5989708 décrit un procédé selon lequel on induit un courant dans un bain d'acier liquide. Une lance à oxygène est introduite dans le bain, et un gaz de brassage est injecté dans le fond du récipient par une brique poreuse située juste en face de la lance à oxygène. On observe des turbulences incontrôlables dans l'acier, une répartition imparfaite du combustible et donc un rendement relativement faible.Document JP-A-5989708 describes a process by which a current is induced in a bath of liquid steel. An oxygen lance is introduced into the bath, and a stirring gas is injected into the bottom of the container by a porous brick located just in front of the oxygen lance. We observe uncontrollable turbulence in the steel, an imperfect distribution of the fuel and therefore a relatively low efficiency.
On connaît par le brevet CH-A-486935 une poche contenant de l'acier liquide au-dessus de la surface duquel est placée une cloche entourant une lance non consommable qui y projette de l'oxygène gazeux en une quantité déterminée. Un combustible métallique est introduit simultanément, également en une quantité déterminée, et la réaction exothermique a lieu au-dessus du bain. Par ailleurs, un gaz inerte est injecté par une autre lance, introduite en oblique à une profondeur d'environ 50 % du bain d'acier, et provoque des mouvements dans celui-ci.Patent CH-A-486935 discloses a pocket containing liquid steel above the surface of which is placed a bell surrounding a lance non-consumable which projects gaseous oxygen therein in a determined quantity. A metallic fuel is introduced simultaneously, also in a determined quantity, and the exothermic reaction takes place above the bath. In addition, an inert gas is injected by another lance, introduced obliquely to a depth of about 50% of the steel bath, and causes movements therein.
L'addition simultanée d'oxygène et de métal au-dessus de la surface du bain requiert l'utilisation d'un dispositif tel qu'une cloche pour récupérer les fumées produites et éviter les pertes de chaleur. Un dispositif tel que décrit ci-dessus présente un faible rendement thermique et même s'il permet d'éviter les problèmes d'usure de lance, il demande beaucoup d'entretien, n'assure pas une parfaite répartition de la température dans l'ensemble du bain d'acier liquide et exige la maîtrise parfaite d'une technologie et d'un procédé complexe et onéreux.The simultaneous addition of oxygen and metal above the surface of the bath requires the use of a device such as a bell to recover the fumes produced and avoid heat loss. A device as described above has a low thermal efficiency and even if it avoids the problems of lance wear, it requires a lot of maintenance, does not ensure a perfect distribution of the temperature in the the entire bath of liquid steel and requires perfect mastery of a complex and expensive technology and process.
La présente invention a pour but de fournir un procédé métallothermique parfaitement contrôlé pour réchauffer efficacement un bain d'acier liquide déjà contenu dans une poche.The object of the present invention is to provide a perfectly controlled metallothermic process for efficiently heating a bath of liquid steel already contained in a pocket.
Elle a également pour but de fournir un procédé particulièrement économique qui permet d'utiliser à cette fin une lance consommable placée à l'intérieur d'un bain liquide, tout en réduisant considérablement l'usure et les risques de défaillances.It also aims to provide a particularly economical process which makes it possible to use for this purpose a consumable lance placed inside a liquid bath, while considerably reducing wear and the risks of failures.
Un autre but de l'invention est de fournir un procédé dans lequel le rendement relatif à la consommation en oxygène et en métal combustible est constant et meilleur que dans les procédés connus de l'état de la technique.Another object of the invention is to provide a process in which the yield relating to the consumption of oxygen and of combustible metal is constant and better than in the processes known from the prior art.
Un but supplémentaire de l'invention est de fournir un procédé permettant d'obtenir une répartition fort homogène du combustible métallique et par là de la température dans le bain d'acier liquide, et ce en un laps de temps satisfaisant, et en utilisant des moyens simples et économiques.A further object of the invention is to provide a method making it possible to obtain a very homogeneous distribution of the metallic fuel and thereby of the temperature in the bath of liquid steel, and this in a satisfactory period of time, and using simple and economical means.
L'invention a encore pour but de fournir un procédé grâce auquel une bonne propreté du bain d'acier liquide peut être obtenue facilement.Another object of the invention is to provide a method by which good cleanliness of the liquid steel bath can be easily obtained.
Un dernier but de l'invention est de fournir un procédé grâce auquel il n'y a pratiquement pas de dégagement de fumées au-dessus du bain et qui n'ajoute pas de pollution à l'environnement.A final object of the invention is to provide a process by which there is practically no release of fumes above the bath and which does not add pollution to the environment.
L'invention a pour objet un procédé pour le réchauffage par métallothermie d'un bain d'acier liquide contenu dans un récipient métallurgique, dans lequel on introduit un combustible métallique et sous la surface duquel on injecte un gaz oxydant et un gaz de brassage dans lequel on crée dans le bain un courant résultant de l'injection d'un gaz de brassage, par un moyen distinct du moyen d'injection du gaz oxydant, et dans lequel on introduit le combustible métallique dans le courant, de manière qu'il soit amené en contact avec le gaz oxydant, ce procédé étant caractérisé en ce que les axes d'injection du gaz oxydant et du gaz de brassage sont décalés l'un par rapport à l'autre, et en ce que l'injection du gaz de brassage génère un courant ascendant dans l'acier liquide, ce courant devenant descendant à l'endroit d'injection du gaz oxydant.The subject of the invention is a method for metallothermic heating of a bath of liquid steel contained in a metallurgical container, into which a metallic fuel is introduced and under the surface of which an oxidizing gas and a stirring gas are injected into which creates in the bath a current resulting from the injection of a stirring gas, by a means distinct from the means for injecting the oxidizing gas, and in which the metallic fuel is introduced into the current, so that it is brought into contact with the oxidizing gas, this process being characterized in that the axes of injection of the oxidizing gas and of the stirring gas are offset with respect to each other, and in that the injection of the gas stirring generates an ascending current in the liquid steel, this current becoming descending at the place of injection of the oxidizing gas.
Selon l'invention, on crée dans le bain un courant contrôlable résultant de l'injection d'un gaz de brassage, par un moyen distinct du moyen d'injection du gaz oxydant, et on introduit le combustible métallique dans ce courant, de manière qu'il soit amené en contact avec le gaz oxydant.According to the invention, a controllable current is created in the bath resulting from the injection of a stirring gas, by a means distinct from the means for injecting the oxidizing gas, and the metallic fuel is introduced into this current, so that it is brought into contact with the oxidizing gas.
Les axes d'injection du gaz de brassage et du gaz oxydant décalés l'un par rapport à l'autre, peuvent par exemple être parallèles entre eux. Ils sont également dans ce cas perpendiculaires à la surface du bain d'acier.The axes of injection of the stirring gas and the oxidizing gas offset from one another, may for example be parallel to each other. They are also in this case perpendicular to the surface of the steel bath.
On a constaté qu'on améliorait de la sorte le rendement de la réaction d'oxydation exothermique pour des quantités de gaz oxydant et de combustible données et qu'on obtenait une excellente répartition de la température dans le bain.It has been found to improve the efficiency of the exothermic oxidation reaction for given quantities of oxidizing gas and fuel and that an excellent temperature distribution was obtained in the bath.
Cette façon de procéder permet en effet de distribuer plus régulièrement le combustible, d'améliorer la décantation des produits de la réaction et d'uniformiser la température du bain d'acier liquide, en favorisant la réaction exothermique dans l'ensemble du bain.This procedure in fact makes it possible to distribute the fuel more regularly, to improve the settling of the products of the reaction and to standardize the temperature of the liquid steel bath, by promoting the exothermic reaction throughout the bath.
De plus, les courants d'acier liquide ainsi générés entraînent des impuretés constituées notamment par les produits de réaction qui peuvent amener des inclusions, vers la partie supérieure du bain, plus particulièrement la scorie.In addition, the streams of liquid steel thus generated entail impurities constituted in particular by the reaction products which can cause inclusions towards the upper part of the bath, more particularly the slag.
Suivant une forme d'exécution préférée de l'invention, les positions relatives des axes d'injection du gaz de brassage et du gaz oxydant et celle du combustible métallique peuvent être définies comme suit: l'injection du gaz de brassage engendre un cône théorique d'aspiration de métal, dont le sommet se trouve à l'endroit où a lieu l'injection. Sa génératrice prolonge l'axe d'injection; sa conicité est fonction du débit du gaz, et de la hauteur d'acier liquide dans le récipient métallurgique. Ce cône à une base définissant sur la surface d'acier liquide un cercle théorique, dont les dimensions peuvent être calculées.According to a preferred embodiment of the invention, the relative positions of the axes of injection of the stirring gas and of the oxidizing gas and that of the metallic fuel can be defined as follows: the injection of the stirring gas generates a theoretical cone metal suction pipe, the top of which is at the injection site. Its generator extends the injection axis; its taper is a function of the gas flow rate, and the height of liquid steel in the metallurgical vessel. This cone has a base defining on the liquid steel surface a theoretical circle, the dimensions of which can be calculated.
Le gaz oxydant réagit avec le combustible dans une zone en substance sphérique. On peut définir sur la surface du bain d'acier un second cercle théorique correspondant dont l'axe d'injection de gaz oxydant constitue le centre, et dont les dimensions peuvent être calculées.The oxidizing gas reacts with the fuel in a substantially spherical area. A corresponding second theoretical circle can be defined on the surface of the steel bath, the center of which is the axis of injection of oxidizing gas, and the dimensions of which can be calculated.
Les deux cercles théoriques engendrés respectivement par l'injection du gaz de brassage et par l'injection du gaz oxydant se recouvrent partiellement en définissant entre eux une zone d'intersection, dans laquelle on introduit le combustible métallique, de préférence de l'aluminium sous forme de fil.The two theoretical circles generated respectively by the injection of the stirring gas and by the injection of the oxidizing gas partially overlap by defining between them an intersection zone, into which the metallic fuel, preferably aluminum under wire form.
Le combustible métallique est de préférence introduit dans la zone d'intersection, à un point d'intersection entre les circonférences des deux cercles théoriques.The metallic fuel is preferably introduced into the intersection zone, at a point of intersection between the circumferences of the two theoretical circles.
Le moyen d'injection de gaz oxydant est de préférence une lance consommable qui peut-être plongée à une profondeur moindre par rapport à l'état de la technique. Des résultats particulièrement avantageux sont obtenus si l'on maintient la profondeur de la lance entre 0 et 15 % de la hauteur du bain d'acier liquide contenu dans le récipient métallurgique, de préférence entre 3 et 30 cm.The means for injecting oxidizing gas is preferably a consumable lance which can be plunged to a lesser depth compared to the state of the art. Particularly advantageous results are obtained if the depth of the lance is maintained between 0 and 15% of the height of the bath of liquid steel contained in the metallurgical vessel, preferably between 3 and 30 cm.
L'usure de cette lance est nettement diminuée par rapport à l'état de la technique et on n'observe pas de remous susceptible d'y provoquer des dégâts.The wear of this lance is significantly reduced compared to the state of the art and there is no eddy likely to cause damage.
Le gaz oxydant est généralement de l'oxygène et le gaz de brassage est de préférence un gaz neutre, généralement de l'argon.The oxidizing gas is generally oxygen and the stirring gas is preferably a neutral gas, generally argon.
Avantageusement, le gaz de brassage est injecté à une profondeur supérieure à 60 % de la hauteur du bain, et de préférence le plus près possible du fond de la poche.Advantageously, the stirring gas is injected at a depth greater than 60% of the height of the bath, and preferably as close as possible to the bottom of the pocket.
Dans un dispositif convenant pour la mise en oeuvre du procédé de l'invention, il est injecté par un élément poreux disposé dans le revêtement de fond du récipient métallurgique. Pour assurer cette fonction, on peut toutefois également prévoir soit en remplacement, soit en supplément, une seconde lance immergée à grande profondeur, de préférence supérieure à 60 % de la hauteur du bain.In a device suitable for implementing the method of the invention, it is injected by a porous element placed in the bottom coating of the metallurgical container. To perform this function, it is however also possible to provide either a replacement or an additional, a second lance immersed at great depth, preferably greater than 60% of the height of the bath.
Pour la mise en route du processus de réchauffage de l'acier, de préférence on démarre successivement :
- l'injection du gaz de brassage,
- l'introduction du combustible métallique dans le courant engendré,
- l'injection du gaz oxydant qui réagit avec le combustible métallique.
- injection of the stirring gas,
- the introduction of metallic fuel into the generated current,
- injecting the oxidizing gas which reacts with the metallic fuel.
- La figure 1 est une vue en élévation d'une coupe schématique d'une poche de coulée,FIG. 1 is an elevation view of a schematic section of a ladle,
- la figure 2 est une vue schématique en plan de celle-ci, etFIG. 2 is a diagrammatic plan view thereof, and
- la figure 3 est un schéma représentant le déroulement d'une opération de réchauffage suivant le procédé de l'invention.Figure 3 is a diagram showing the progress of a reheating operation according to the method of the invention.
Les figures 1 et 2 représentent un récipient métallurgique tel que par exemple une poche de coulée 1, revêtue d'un matériau réfractaire 3 et présentant, à sa partie inférieure, un trou de coulée 5 muni d'un équipement 7 d'ouverture et de fermeture dudit trou.Figures 1 and 2 show a metallurgical container such as for example a
Un gaz de brassage, en l'occurrence de l'argon, est injecté par un élément poreux 9 placé dans le fond de la poche de coulée 1. L'axe d'injection 91 constitue l'axe d'un cône d'aspiration de métal 92. L'argon monte vers la surface du bain 11 et s'évacue ensuite librement dans l'atmosphère. La base du cône 92 est située au niveau de la surface du bain. Elle a la forme d'un cercle 93 et est représentée par un trait continu à la figure 2.A stirring gas, in this case argon, is injected by a porous element 9 placed in the bottom of the
Un fil d'aluminium 13 servant de combustible métallique est introduit dans le bain 11.An
Ce combustible réagit avec l'oxygène qui est ensuite injecté dans le bain. La réaction est fortement exothermique et sera avantageusement utilisée pour réchauffer le bain efficacement et rapidement et en obtenant une excellente répartition de la température et ce grâce à la disposition relative des différents éléments.This fuel reacts with oxygen which is then injected into the bath. The reaction is highly exothermic and will advantageously be used to heat the bath efficiently and quickly and by obtaining an excellent distribution of the temperature, thanks to the relative arrangement of the various elements.
L'oxygène est injecté par une lance consommable 15, en matériau réfractaire, qui plonge dans le bain d'acier liquide 11 sur une profondeur pouvant aller de 0 à 15 % de la hauteur du bain, considéré sous la zone de scorie 12 présente à la surface.The oxygen is injected by a
Le maintien de la profondeur d'immersion de la lance 15 est avantageusement contrôlé par des moyens connus en soi, et adapté en fonction de la vitesse d'usure moyenne de la lance.Maintaining the immersion depth of the
On peut définir un axe théorique d'injection du gaz oxydant 151 dans le bain d'acier liquide, cet axe se situant dans le prolongement de la lance consommable 15.A theoretical axis of injection of the oxidizing
Comme on le voit à la figure 1, le gaz de brassage entraîne l'aluminium dans le mouvement descendant qu'il impose à l'acier liquide près de la surface du bain 11, et l'amène près de l'extrémité de la lance 15 d'injection du gaz oxydant. Il réagit exothermiquement avec ce dernier.As can be seen in FIG. 1, the stirring gas drives the aluminum in the downward movement which it imposes on the liquid steel near the surface of the
La réaction a lieu dans une zone en substance sphérique 152 dont les dimensions dépendent du débit du gaz oxydant, de sa pureté et de la teneur locale en métal combustible.The reaction takes place in a substantially
On peut donc, lorsque les débits d'introduction du combustible et du gaz oxydant sont sensiblement constants et dans le rapport de combustion, calculer le diamètre d'une sphère à la périphérie de laquelle tout l'oxygène a réagi. Sur la figure 1, on a représenté une zone de réaction 152 qui présente une forme en substance ellipsoïdale. Le caractère ellipsoïdal est plus ou moins marqué en fonction de l'importance du débit du gaz oxydant.It is therefore possible, when the introduction rates of the fuel and the oxidizing gas are substantially constant and in the combustion ratio, calculate the diameter of a sphere at the periphery of which all the oxygen has reacted. FIG. 1 shows a
Comme on le verra plus en détail ci-dessous, on introduit le combustible et le gaz oxydant avec un léger décalage temporel, dont on tient compte dans le calcul.As will be seen in more detail below, the fuel and the oxidizing gas are introduced with a slight time difference, which is taken into account in the calculation.
On peut par ailleurs représenter, sur la surface du bain, un second cercle théorique 153 dont le centre correspond à l'axe d'injection du gaz oxydant et dont le diamètre est celui de la sphère. Un tel cercle est représenté en pointillé à la fig.2. Il peut également être défini dans le cas d'une zone de réaction ellipsoïdale.It is also possible to represent, on the surface of the bath, a second
Le diamètre du cercle 93 défini par la base du cône engendré par le gaz de brassage peut être déterminé avec précision. Des études donnent une valeur d'environ 10° pour le demi- angle au sommet du cône 92.The diameter of the
En fonction de cette donnée, du débit du gaz et de la valeur moyenne de la hauteur du bain 11 dans la poche, on obtient une excellente approximation des dimensions du cercle 93.Depending on this data, the gas flow rate and the average value of the height of the
Comme on le voit bien à la fig.2, les cercles 93 et 153 définissent entre eux une zone d'intersection 915 dans laquelle on introduit le fil d'aluminium 13; de préférence à un des points d'intersection entre les deux circonférences. Cette disposition permet d'obtenir un rendement maximum et une excellente répartition de la température dans le bain.As can be seen in FIG. 2, the
La fig.3 illustre le déroulement d'une opération de réchauffage d'un bain d'acier liquide selon le procédé de l'invention.Fig.3 illustrates the course of a heating operation of a bath of liquid steel according to the method of the invention.
Le graphique montre l'évolution dans le temps des débits du gaz de brassage, en l'occurrence de l'argon (Ar), du combustible en l'occurrence de l'aluminium (Al) et du gaz oxydant, en l'occurrence de l'oxygène (O₂).The graph shows the evolution over time of the flows of the mixing gas, in this case argon (Ar), of the fuel in this case of aluminum (Al) and of the oxidizing gas, in this case oxygen (O₂).
Pour la mise en route du réchauffage du bain fondu, on démarre l'injection du gaz de brassage, puis on introduit le fil de combustible métallique et enfin on démarre l'injection d'oxygène.To start the heating of the molten bath, the injection of the stirring gas is started, then the metal fuel wire is introduced and finally the oxygen injection is started.
Le courant descendant induit par le gaz de brassage amène perpétuellement près du point d'injection du gaz oxydant de nouvelles quantités d'acier liquide chargé d'aluminium, qui entre en réaction avec l'oxygène. Un mouvement tournant est engendré dans le bain et permet notamment la migration des impuretés vers la scorie.The downdraft induced by the stirring gas perpetually brings new quantities of aluminum-charged liquid steel near the injection point of the oxidizing gas, which reacts with oxygen. A rotating movement is generated in the bath and in particular allows the migration of impurities towards the slag.
Bien entendu, le brassage continue ensuite dans le fond de la poche et l'acier liquide ainsi réchauffé se répartit dans les zones moyenne et haute, ce qui permet d'obtenir en fin d'opération une parfaite répartition de la chaleur dans tout le bain.Of course, the stirring then continues in the bottom of the ladle and the liquid steel thus heated is distributed in the medium and high zones, which makes it possible to obtain, at the end of the operation, a perfect distribution of the heat throughout the bath. .
Les injections sont poursuivies jusqu'à l'obtention de la température voulue. Une fois cette température atteinte, on retire la lance à oxygène tout en maintenant un léger débit jusqu'à ce que cette lance soit sortie du bain, évitant ainsi le bouchage de conduit d'insufflation. Le brassage par le gaz neutre est également maintenu pendant un certain temps de manière à favoriser l'élimination des impuretés résultant de la réaction ainsi que les débris dus à l'érosion de la lance.The injections are continued until the desired temperature is obtained. Once this temperature has been reached, the oxygen lance is removed while maintaining a slight flow rate until this lance is removed from the bath, thus avoiding blockage of the insufflation duct. The mixing with neutral gas is also maintained for a certain time so as to favor removal of impurities resulting from the reaction as well as debris due to erosion of the lance.
Il est bien entendu que l'invention n'est pas limitée aux formes d'exécution décrites mais qu'elle s'étend au cadre défini par les revendications.It is understood that the invention is not limited to the embodiments described but that it extends to the framework defined by the claims.
Ainsi par exemple, selon une autre variante, on peut prévoir une lance supplémentaire d'injection de gaz de brassage au lieu de ou en plus de l'élément poreux 15.Thus, for example, according to another variant, an additional lance for injecting stirring gas can be provided instead of or in addition to the
On peut encore utiliser d'autres gaz oxydants que l'oxygène pur, d'autres gaz de brassage que l'argon et d'autres combustibles métalliques que l'aluminium.It is also possible to use other oxidizing gases than pure oxygen, other brewing gases than argon and other metallic fuels than aluminum.
Claims (8)
- Process of heating up metallurgically a liquid steel bath (11) contained in a metallurgical container (1), into which a combustible metal is introduced and under the surface of which an oxidizing gas and a mixing gas are injected, wherein there is created in the bath (11) un stream resulting from the injection of a mixing gas through a means (9) distinct from the injecting means (15) for the oxidizing gas, and wherein the combustible metal (13) is introduced into the stream so as to be brought into contact with the oxidizing gas, characterized by the fact that the injection axes of the oxidizing gas and the mixing gas are offset one with each other, and the injection of the mixing gas generates an upward stream in the liquid steel, said stream taking a downward direction at the injection point of the oxidizing gas.
- Process according to claim 1, characterized by the fact that a consumable lance (15) is selected as an injection means for the oxidizing gas, which is maintained at a depth of 0 to 15 % of the height of the liquid steel bath contained in the metallurgical container, preferably at a depth between 3 and 30 cm.
- Process according to any of claims 1 and 2, characterized by the fact that the mixing gas is injected at a higher depth than 60 % of the bath height.
- Process according to claim 1, characterized by the fact that the injection axes for the mixing gas (91) and for the oxidizing gas (151) are parallel to each other.
- Process according to claim 4, characterized by the fact that the axes (91, 151) are perpendicular to the bath surface (11).
- Process according to any of claims 1 to 5, characterized by the fact that the injection of the mixing gas generates a metal-aspirating theorical cone (92), the vertex of which is at the point where the injection takes place, the generatrix extends the injection axis (91) and the base defines with the bath surface (11) a circle (93), the oxidizing gas reacts with the combustible (13) in a substantially spherical zone (152) the projection of which defines a circle (153) on the bath surface (11), and both circles (93, 153) are overlapping partially so as to define an intersection zone (915) into which the combustible (13) is introduced.
- Process according to claim 6, characterized by the fact that the combustible metal (13), preferably an aluminium wire, is introduced into the intersection zone (915) at an intersection point between the circumferences of the two circles (93, 153).
- Process according to any of preceding claims, characterized by the fact that the following steps are carried out successively :- injection of the mixing gas,- introduction of the combustible metal into the stream generated, and- injection of the oxidizing gas which reacts with the combustible metal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT9191910980T ATE105025T1 (en) | 1990-06-29 | 1991-06-28 | METHOD OF REHEATING A STEEL BATH. |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BE9000673A BE1004483A3 (en) | 1990-06-29 | 1990-06-29 | Heating method for bath liquid steel. |
| BE9000673 | 1990-06-29 | ||
| PCT/BE1991/000044 WO1992000391A1 (en) | 1990-06-29 | 1991-06-28 | Liquid steel bath reheating method and device for implementing same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0536185A1 EP0536185A1 (en) | 1993-04-14 |
| EP0536185B1 true EP0536185B1 (en) | 1994-04-27 |
Family
ID=3884855
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP91910980A Expired - Lifetime EP0536185B1 (en) | 1990-06-29 | 1991-06-28 | Liquid steel bath reheating method |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US5316566A (en) |
| EP (1) | EP0536185B1 (en) |
| JP (1) | JP2889901B2 (en) |
| AU (1) | AU7994191A (en) |
| BE (1) | BE1004483A3 (en) |
| DE (1) | DE69101839T2 (en) |
| ES (1) | ES2051594T3 (en) |
| PL (1) | PL169724B1 (en) |
| WO (1) | WO1992000391A1 (en) |
Families Citing this family (4)
| 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 |
| RU2121513C1 (en) * | 1998-01-22 | 1998-11-10 | Евгений Анатольевич Иванов | Process of steel treatment in ladle |
| RU2125614C1 (en) * | 1998-05-06 | 1999-01-27 | Шатохин Игорь Михайлович | Method of ladle heating of steel |
| RU2154677C1 (en) * | 1999-07-07 | 2000-08-20 | ОАО "Новолипецкий металлургический комбинат" | Method of treating steel in ladle |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH486935A (en) * | 1966-09-02 | 1970-03-15 | Feichtinger Heinrich Ing Dr | Process and device for heating melts by exothermic reactions |
| SE449373B (en) * | 1977-07-01 | 1987-04-27 | Dso Cherna Metalurgia | SET AND DEVICE FOR REFINING IRON-BASED MELTORS IN ELECTRICAL REACTION OVEN |
| US4187102A (en) * | 1978-08-24 | 1980-02-05 | Union Carbide Corporation | Method for controlling the temperature of the melt during pneumatic refining of steel |
| LU84472A1 (en) * | 1982-11-17 | 1984-06-13 | Arbed | PROCESS AND PLANT FOR THE TREATMENT OF POCKET STEEL |
| US4761178A (en) * | 1987-08-24 | 1988-08-02 | Bethlehem Steel Corporation | Process for heating molten steel contained in a ladle |
| JP2617948B2 (en) * | 1987-10-12 | 1997-06-11 | 新日本製鐵株式会社 | Ladle refining method for molten steel |
| IN172394B (en) * | 1988-07-22 | 1993-07-17 | Boest Alpine Stahl Donawitz Ge |
-
1990
- 1990-06-29 BE BE9000673A patent/BE1004483A3/en not_active IP Right Cessation
-
1991
- 1991-06-28 ES ES91910980T patent/ES2051594T3/en not_active Expired - Fee Related
- 1991-06-28 DE DE69101839T patent/DE69101839T2/en not_active Expired - Fee Related
- 1991-06-28 AU AU79941/91A patent/AU7994191A/en not_active Abandoned
- 1991-06-28 WO PCT/BE1991/000044 patent/WO1992000391A1/en not_active Ceased
- 1991-06-28 EP EP91910980A patent/EP0536185B1/en not_active Expired - Lifetime
- 1991-06-28 JP JP3510510A patent/JP2889901B2/en not_active Expired - Fee Related
- 1991-06-28 US US07/949,820 patent/US5316566A/en not_active Expired - Lifetime
- 1991-06-28 PL PL91297362A patent/PL169724B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| DE69101839D1 (en) | 1994-06-01 |
| DE69101839T2 (en) | 1994-09-15 |
| WO1992000391A1 (en) | 1992-01-09 |
| ES2051594T3 (en) | 1994-06-16 |
| JPH05507966A (en) | 1993-11-11 |
| US5316566A (en) | 1994-05-31 |
| AU7994191A (en) | 1992-01-23 |
| PL169724B1 (en) | 1996-08-30 |
| EP0536185A1 (en) | 1993-04-14 |
| BE1004483A3 (en) | 1992-12-01 |
| JP2889901B2 (en) | 1999-05-10 |
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