EP1097246B1 - Method and device for sealing a tap hole in metallurgical containers - Google Patents

Description

The invention relates to a method and a device for sealing a tap opening in metallurgical vessels.

Recently there has been a tendency to use steels with a high degree of purity Manufacture "Clean Steel" to meet the increasing demands for better ones Steel properties to meet. The separation of melt and slag in the electric furnace or converter with subsequent secondary metallurgy is an essential one Influencing factor with regard to the degree of purity.

Some tapping systems are known from the prior art. In a conventional one The electric arc furnace is tapped, for example, from the side Tilt the furnace vessel. The furnace is tilted to the rack side for tapping, after reaching the desired tapping weight, the outflow of the melt ended by a quick tilt back. Here it is unavoidable that slag partially runs out of the tap hole with the melt jet.

After the tapping has been carried out and the tipping back, the tapping opening is opened for one Another batch prepared by closing the opening with a closing plate and sand is poured into this opening. The sand filling process is either carried out manually or by a mechanical conveyor system. Optimal filling opening with sand is not possible with the manual filling process. It can also this step, if cleaning work needs to be carried out, is time consuming and labor intensive his.

Furthermore, there is a low-slag tapping system in a converter by means of a Floats or cinder blockers known. Here, a swimmer, its specific weight between that of the molten steel and that of the Schlakke lies in the weld pool above the vortex caused by the outflow brought in. The float sinks with the flowing steel melt and closes the tap hole. However, it proves disadvantageous that sealing the tap opening depends solely on the sinking melt / slag boundary layer is and is otherwise not influenced. It is also a completely slag free Leakage of the melt cannot be achieved with this float solution.

The so-called AMEPA system has become known for racking in pans. This system is mainly used to control the tapping from the pan into the Distributor of a continuous caster used. It is a racking system according to the electromagnetic principle. The termination of the racking and the Separation process between the melt and slag is achieved via a sensor that is installed on the pan spout. There is a slide system that follows Finding that slag runs out, closes the tap hole. A slacker Parting off is not possible with this principle, since the sensor only reacts when part of the slag has already flowed through the opening.

Furthermore, a pneumatic tapping system is state of the art, from the outside closes the metallurgical vessel. However, there is a high risk of splashing.

From the German patent DE 33 27 671 is also a device for largely slag-free tapping of metal melts, especially of Melting steel, known from metallurgical vessels. This is primarily about Task, vortex formation and immersion of a shut-off to prevent mixing of slag and melt. For this, a Shut-off body proposed, which can be raised and lowered by means of a rod Lifting system can be inserted into the metallurgical vessel. By lowering of the flow body and stop just above the bottom of the vessel The negative potential vortex is better bound at the tap opening. It is described that the type of flow body to reduce swirl though can also be completely lowered to the tap opening on the base of the vessel, to end the racking. But the flow body is not complete taken from the tap hole, but this sits on the opening on. However, with all mentioned tapping methods from the prior art only a low-slag, no slag-free tapping possible. This means, among other things, that the oxygen content in the melt due to the entrained oxidic slag is increased, which results in increased deoxidation. The oxygen content of the FeO in the slag makes desulphurization and degassing difficult.

JP-A-58 031 018 describes a control system which is dependent on the weight of the tapped melt for a stopper which can be moved from above through the melt into a tapping opening.

WO-A-9 718 050 describes a closing plate which can be brought up to the tap opening from below from the outside of the vessel and which is present in addition to a stopper acting from above.

Finally, EP 0 315 311 B1 describes a stopper for closing tapping openings known in metallurgical vessels. This plug consists of one cylindrical shaped container made of metal with two plates at its ends is provided. In this case, the end of the Container and the corresponding inner plate with a gap spaced apart arranged. The metallic container takes refractory material, such as Sand, on. This sand is surrounded by a plastic sheet. The stopper is provided with a plunger, which is used to place the plug in the hole the outer plate against the inner plate along a rod guide, which penetrates the sand mass is moved. This will make the plastic sheet torn. This process is supported by a serrated edge of the container. The sand emerges from the gap and into the gap between the container and the tap hole and thus creates a sealing connection. The plunger is then turned off while the metallic container is in the tap hole remains.

The present invention is therefore based on the object, a method and to create a racking system with which a slag-free racking is easy and inexpensive can be carried out in a metallurgical vessel and thus with steels high purity can be produced.

This object is achieved by means of the features of the method claim 1 and that of the device claim 7 solved. Advantageous configurations the invention are disclosed in the subclaims.

The essence of the invention is the creation of a tapping plug system with which the tapping opening of a metallurgical vessel can be optimally sealed. This is achieved according to the device by a special design of the stopper. According to the method, it is proposed to insert the stopper into the tap opening to control, for example, depending on the weight of the tapped Steel, the bathroom mirror or via a slag detection system. There are preferably automatic, but also semi-automatic or manual controls possible. The time of introduction can be controlled selectively or, for example via a signal which is via a visual scanning via a screen indicator is determined.

The stopper according to the invention consists of a stopper casing which is flowable Fabric that picks up. This filled plug casing is made of the liquid metal or introduced into the tap opening from outside the metallurgical vessel. Subsequently the tap opening is closed, for example, by means of a closing plate. The invention takes advantage of the fact that the material of the plug casing with regard to its consistency and / or its shape due to the influence of temperature changes that the flowable material spreads sealingly in the tap opening can. The material of the plug casing is preferably one temperature insulating material, for example cardboard or wood.

The flowable material is preferably filling sand. This replicates the disintegration of the shell at the contact area with the molten metal, the tapping opening sealing sintered layer. This means an additional sealing effect. Since the amount of filling sand is dosed in the stopper casing and depending on Wear of the tap hole can be varied, the tap hole with a optimal amount of sand can be sealed. It is thus avoided that the sand not completely filling the hole for sealing. Thus, problems with opening bypassed the tap hole.

The insertion means for the plug casing are preferably a metal rod or a metal tube that can be moved through the melt to the tap opening are. The metal rod or the metal tube advantageously consists of links, which allow them to be moved out of the horizontal using an arcuate guide to move the vertical.

These are to protect the metal rod or pipe from the hot melt surrounded by a protective tube. This protective tube also consists of one opposite the molten metal is only resistant for a short time. Preferably acts This material for the plug casing and the protective tube is cardboard, which coked in the molten metal. It is also all other types of materials conceivable, the consistency due to the temperature influence of the molten metal change, which includes total dissolution, or change their shape, by losing firmness.

The filling sand absorbed by the casing can contain binders which are at temperatures disintegrate at the level of the molten metal. It is also conceivable that the Filling sand within the casing is surrounded by an intermediate protective layer and vacuum-sealed is. This intermediate protective layer is advantageously a film, that dissolves at the given temperatures.

A support plate lies on top of the filling sand. By means of the support plate Rod or tube press the filling sand further down.

Another embodiment of the invention provides that in addition to the plug casing as the first chamber for receiving filler the cavity of the protective tube as second chamber is used. This second chamber serves as a storage chamber for filler. The second chamber is filled with filler in particular when the The tap hole diameter has increased due to wear is.

If the plug insertion means up to the tap hole is one Acting rod, this second chamber is located between the axially through the Protective tube feasible rod and the inner surface of the protective tube. The amount the filler in this second chamber can be selected as required. If if the insertion means is a tube, it penetrates with it surrounding protective tube the first chamber. The second chamber is in the cavity of the insertion tube formed inside and above the first chamber. By both Embodiments provide that the bottom of the first chamber with a Grafting, preferably made of ceramic, is provided. To protect the filler when The chambers as well as the stopper pass through the hot melt surrounding the temperature-insulating plug casing. This grafting is due to a Pressurization can be moved through the rod or tube. Through the movement the plug is moved, the cover torn on the bottom, and filler comes out.

The proposed method and the plug show the advantage of a slag-free Tapping. When using the process in the electric furnace, the secondary metallurgical Treatment, especially with regard to the current requirement after "Clean Steel", significantly simplified. The uncontrollable aluminum erosion is prevented by the accompanying slag. The invention brings about a saving the deoxidizing agent, the winding wires such as CaSi and the synthetic Slag. Furthermore, favorable conditions for desulfurization and degassing created The casting properties are improved.

Figur 1

eine vergrößerte Darstellung des Stopfens des Abstichsystems beim Vorgang des Eintauchens in die Abstichöffnung eines Elektroofens;

Figur 2

eine vergrößerte Darstellung des erfindungsgemäßem Stopfens bei vollständiger Aufnahme in der Abstichöffnung;

Figur 3

eine vergrößerte Darstellung des erfindungsgemäßen Stopfens beim Vorgang der Temperatureinwirkung auf die Stopfenhülle;

Figur 4

eine Darstellung des Abstiches in einem Elektroofen mit dem automatisch gesteuerten Abstichsystem;

Figur 5

eine Darstellung des Abstichendes in einem Elektroofen mit dem automatisch gesteuerten Abstichsystem.

Figur 6

eine vergrößerte Darstellung einer Ausführungsform des Stopfens nach dem Zweikammer-System in in eine Abstichöffnung eines metallurgischen Gefäßes eingeführten Position;

Figur 7

eine vergrößerte Darstellung einer weiteren Ausführungsform des Stopfens nach dem Zweikammer-System in in eine Abstichöffnung eines metallurgischen Gefäßes eingeführten Position.

The method according to the invention makes it possible to end the tapping at a precisely determined target tapping weight. The time for inserting the stopper into the tap opening is controlled, for example, as a function of the weight of the melt that has already been tapped off by means of suitable systems. Furthermore, the time of introduction can be controlled by means of a bath level measuring system or a slag early detection system.
Further details and advantages of the invention emerge from the claims and the following description. Here show:

Figure 1

an enlarged view of the plug of the tapping system during the process of immersion in the tap hole of an electric furnace;

Figure 2

an enlarged view of the stopper according to the invention when fully received in the tap opening;

Figure 3

an enlarged view of the stopper according to the invention during the process of temperature action on the stopper casing;

Figure 4

a representation of the racking in an electric furnace with the automatically controlled racking system;

Figure 5

a representation of the tapping end in an electric furnace with the automatically controlled tapping system.

Figure 6

an enlarged view of an embodiment of the plug according to the two-chamber system in a position inserted into a tap hole of a metallurgical vessel;

Figure 7

an enlarged view of another embodiment of the plug according to the two-chamber system in a position inserted into a tap hole of a metallurgical vessel.

Figure 1 shows a partial enlargement of the plug 1 of the tapping system during the immersion process into the tap hole 2 in the bottom 3 of an electric furnace 4. With 5 the molten steel, 6 denotes the lighter slag.

The stopper 1 comprises a casing 7 and a core 8 of filling sand, which of the Shell 7 is surrounded as a protective jacket. In this embodiment, the plug 1 by means of a metal rod 9 into the tap opening 2 via a lifting system 10 from the interior of the vessel coming in.

The metal rod 9 acts on the filling sand 8 via a support grid 11. A graft 12 forms the end of the filling sand core 8 to the bottom region of the plug casing. The The diameter of the plug corresponds at least approximately to the diameter of the Tap hole 2 at its lower end.

For temporary protection of the metal rod 9, this is covered with a protective tube 13. This tube can be formed as a whole with the casing 7 of the stopper or attached to this. In the first case, the protective tube 13 forms in combination with the shell 7 the outer casing for the metal rod 9 and the filling sand core 8. The protective tube 13 can be made of the same material as the cover of the plug. According to the invention, this is a material that influences the temperature the melt can only withstand for a certain time. The one described here The shape of the cover is made of cardboard, which cokes due to the high temperatures.

During the immersion step of the stopper 1 in the tap opening 2 by means of the Metal rod 9 presses this onto the support grid 11, which then continues on the sand core 8 acts, which is supported by the plug 12. In addition, the filling sand also vacuum-sealed by means of an intermediate protective film (not shown) that dissolves at the existing temperatures. Furthermore, the Sand with binders that disintegrate at high temperatures, such as synthetic resin, be bound.

After or simultaneously with the insertion process of the plug 1 at high speed in the tap opening 2, the tap opening 2 is from the outside of the closed metallurgical vessel. This closed state shows Figure 2. The closure means is a closing plate 14. It can also be any other type of conventional closure means. After the closing process the metal rod 9 by automatically releasing a clamping device (not shown) separated and withdrawn through the interior of the vessel.

the influences resulting from the temperature influence can be seen in FIG. The plug casing 7, consisting of cardboard, coked (15). The metal pillar from remaining melt and slag presses the flowable sand, which is no longer is stabilized by a cover, down and to the side. This spreads the Sealing sand in the tap hole. It can also be seen that the Material of the protective tube 13 has completely dissolved. At the contact zone between the filling sand and the liquid metal or the slag will result in a Sintering reaction. This sintered layer 16 means an additional sealing layer. After forming this seal, the furnace can be scraped again for the next one Batch to be infested.

Figures 4 and 5 show an embodiment of the tapping system according to the invention using the example of an electric furnace during a racking (Figure 4) and at the tapping end (Figure 5). A section of an electric furnace 4 is shown. The closing plate is used for tapping the furnace 4 which cannot be tilted in the embodiment 14 pushed back below the tap hole 2. The one in the tap hole 2 located sand runs out, and the molten steel 5 is in a Pan 17 filled. In normal driving style, the electric oven is sufficient Swamp driven so that when tapping a sufficient bath height above the tap opening is present and there are no vortices that cause unwanted running the slag could cause. To prevent the end of the racking the bath level sinks too far, the oven 4 is relatively lower Oriel or with a tap hole directly in the stove or with a large one Swamp.

The weight of the tapped melt is determined by means of a weighing device 18 measured. The weighing device is a weighing cell located below the pan 17 are arranged in the trolley 19. The current weight will be detected by measuring signals from a measuring system 20 and into a data processing system 21 fed. After reaching the desired tapping weight is the metal rod 9 of the tapping system via a lifting device 10, which is controlled by means of a plug control system 22, vertically through the interior of the vessel is moved in order to close the tap opening 2 with the stopper 1. Such a lifting device is advantageously the extreme operating conditions customized. In an alternative embodiment of a tilting oven, could this lifting device can be arranged on the furnace vessel or on the tilting platform. In addition - for example with fluctuations in the bath height - a known one Early slag detection system may be provided. This is on the data processing system 21 and the plug control system 22 connected. Even if the desired molten steel weight has not yet been reached, the plug is inserted into the The tap opening is driven as soon as slag has been detected. The rapid reaction of the tapping system according to the invention makes it possible to prevent slag from leaking.

Figure 6 shows a first embodiment of the plug according to the two-chamber system. The components which correspond to FIGS. 1 to 3 are corresponding Provide reference numbers. Figures 6 and 7 do not show the initial state of the stopper, but the state of insertion into the tap hole. In the initial state the stopper is made from a cardboard-covered first chamber and a second chamber, which is also covered with cardboard. The floor the first chamber is detachably closed with a plug that is inside of the protective covering.

According to FIG. 6, the first chamber is designated 123, the second chamber 124. The second chamber extends between the inner surface of the plug casing 7 of the first chamber 123 adjacent protective tube 113 and the outer surface of the metal rod 109. The plug is used to empty the chamber system 112 by pressurizing rod 109 from the bottom of the first chamber detached and undergoes a pushing movement towards the outside of the vessel. in this connection the bottom wrapper tears (no longer shown) and filler sand 125 emerges. It is also conceivable that the plug by contact with the axially movable rod is proceeding steadily. The diameter of the plug is in the two-chamber system dimensioned so that a leadership within the narrowing Tapping is possible.

According to the embodiment of FIG. 7, the metal rod is through a hollow tube 226 replaced. The protective tube 213 receives this tube 226 and penetrates the Top of the chamber 223 covering part of the plug casing 7 and thus the first Chamber 223. The second chamber 224 is in the cavity of the insertion tube 226 educated. Experienced by axial movement of the insertion tube 226 to the protective tube 213 the plug 212 an impact movement and tears the bottom-side wrapping (not more shown). Filling sand 225 emerges. If the stopper is caused by a contact movement is moved, a back process is for the discharge of the filling sand from the second chamber of the tube 213 necessary.

Claims (15)

1. A method for sealing a tap opening in metallurgic vessels, wherein a stopper covering (7) that accommodates a heat-resistant, free-flowing substance (8) is inserted into the tap opening, wherein the stopper (1) is inserted into the tap opening by means of a metal rod (9; 109) or a metal tube (226), and wherein the temperature of the molten bath changes the material of the stopper covering in such a way that the free-flowing substance spreads and seals the tap opening, characterized by the fact that the time at which the stopper covering (7) is inserted into the tap opening by means of the metal rod (9; 109) or the metal tube (226) after having been guided through the molten bath is controlled, wherein the metal rod or the metal tube is surrounded by a protective tube (13) that, analogous to the material of the stopper covering, consists of a material that is only briefly resistant to the molten bath, and wherein the briefly resistant material consists of a substance in the form of cardboard or wood which provides a temporary temperature insulation, and by the fact that the tap opening (2) is closed from the outside of the vessel, wherein the covering material (7) of the stopper cokes and disintegrates in the tap opening, and wherein the material of the protective tube also cokes and disintegrates.
2. The method according to Claim 1, characterized by the fact that the free-flowing substance (8) in the form of filler sand forms a sintered layer (16) that seals the tap opening after the covering disintegrates on the contact surface with the molten bath.
3. The method according to Claim 1 or 2, characterized by the fact that the time at which the stopper (1) is inserted into the tap opening is controlled in dependence on the weight of the already tapped molten bath.
4. The method according to Claim 1 or 2, characterized by the fact that the time at which the stopper (1) is inserted into the tap opening is controlled by means of a slag detection system.
5. The method according to Claim 1 or 2, characterized by the fact that the time at which the stopper (1) is inserted into the tap opening is controlled in dependence on the bath level in the smelting unit.
6. The method according to one of Claims 1, 3, 4 or 5, characterized by the fact that the insertion time is controlled automatically or semiautomatically or manually.
7. A tapping system for carrying out the method according to one of Claims 1 - 6 for sealing a tap opening in metallurgic vessels, wherein said system contains a stopper (1) with a covering (7) that fits into the tap opening and accommodates a heat-resistant, free-flowing substance (8) for sealing the tap opening, wherein the covering (7) consists of a material that is only briefly resistant to the molten bath with respect to its consistency and/or shape, and wherein the stopper (1) contains a metal rod (9, 109, 226) or a metal tube, characterized by the fact that the metal rod (9, 109) or the metal tube (226) serve for guiding the stopper (1) into the tap opening through the molten bath, wherein the metal rod or the metal tube is surrounded by a protective tube (13) of a material that is only briefly resistant to the molten bath, and wherein the material of the covering (7), as well as the material of the protective tube, consist of a substance in the form of cardboard or wood which provides a temporary temperature insulation and cokes in the molten bath.
8. The tapping system according to Claim 7, characterized by the fact that said system comprises automatically controllable means (9, 10) for inserting the stopper covering (7) into the tap opening.
9. The tapping system according to Claim 7, characterized by the fact that the rod (9) or the tube (226) consists of links that make it possible to move the rod or tube from the horizontal position into the vertical position with the aid of an arc-shaped guide.
10. The tapping system according to one of Claims 7 - 9, characterized by the fact that support means (11) of the rod (9) or the tube (226) act upon the free-flowing substance (8) in the form of filler sand.
11. The tapping system according to one of Claims 7 - 9, characterized by the fact that the stopper covering (7) serves as a first chamber (123, 223) for accommodating the free-flowing substance (8), and by the fact that the hollow space of the protective tube (113, 213) additionally serves as a second chamber (124, 224) for accommodating the free-flowing substance (8).
12. The tapping system according to Claim 11, characterized by the fact that the protective tube (113) is arranged on the stopper covering (7), and by the fact that the metal rod (109) can be axially displaced relative to the protective tube such that it penetrates both chambers.
13. The tapping system according to Claim 12, characterized by the fact that the protective tube (213) penetrates the stopper covering (7), and by the fact that the metal tube (226) that accommodates the additional free-flowing substance (8) can be displaced within the protective tube (213), namely axially thereto.
14. The tapping system according to one of Claims 11, 12 or 13, characterized by the fact that a removable plug (112, 212) seals the bottom of the first chamber (123, 223), and by the fact that pressure can be exerted upon the plug by means of the rod (109) or the metal tube (226), wherein said pressure causes the plug to move such that the chamber(s) is/are opened and the free-flowing substance (8) is released.
15. The tapping system according to one of Claims 7 - 14, characterized by the fact that the free-flowing substance (8) consists of filler sand with binders that disintegrate at metal-smelting temperatures, or by the fact that the filler sand is surrounded by an intermediate protective layer within the covering and vacuum-sealed.

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