Metallurgical apparatus – Process – Plugging or tapping
Reexamination Certificate
2001-06-18
2002-10-29
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Process
Plugging or tapping
C266S272000, C222S590000, C222S597000
Reexamination Certificate
active
06471911
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method and a device for sealing a tap hole in metallurgical containers.
2. Description of the Related Art
The invention relates to a method and a device for sealing a tap hole in metallurgical containers.
Recently, there has been a tendency to produce steels of a high degree of purity, so-called clean steel, in order to thus fulfill the increasing requirements for improved steel properties. The separation of molten mass and slag in the electric furnace or converter with subsequent secondary metallurgy is an essential influencing factor with respect to the degree of purity.
From the prior art several tapping systems are known. In a conventional electric arc furnace tapping is carried out, for example, by lateral tilting of the furnace vessel. The furnace is tilted toward the tapping side for tapping, and the outflow of the molten mass is terminated by a fast return tilting after reaching the desired tapping weight. In this connection, it cannot be avoided that slag flows partially with the stream of the molten mass out of the tap hole.
After termination of tapping and the return tilting movement, the tap opening is prepared for a new batch in that the opening is closed by a closure plate and sand is filled into the opening. The sand filling process is carried out either manually or by an automated conveying system. An optimal filling of the opening with sand is not possible for a manual filling process. Moreover, this step, in the case that cleaning work has to be carried out, is time-consuming and labor-intensive.
Moreover, the slag-poor tapping system for a converter is known in connection with a float or slag stopper. In this context, a float whose specific weight is between that of the molten mass of steel and of the slag is introduced into the molten bath above the eddy caused by the outflowing molten mass. The float is lowered together with the outflowing molten mass of steel and closes the tap opening. A disadvantage is, however, that the sealing of the tap opening depends only on the lowered molten mass/slag interface and cannot be influenced otherwise. Moreover, a completely slag-free outflowing of the molten mass is not possible with this float solution.
For tapping in ladles, the so-called AMEPA system is known. This system is primarily employed for controlling the tapping from the ladle into the distributor of a continuous casting device. This is a tapping system according to the electromagnetic principal. The termination of tapping and the separation between molten mass and slag are achieved by a sensor which is mounted within the outflow of the ladle outlet. A slide system is provided which closes off the tap opening after it has been determined that slag also flows out. A slag-free tapping is not possible by this solution because the sensor reacts only after a portion of the slag has already flown through the opening.
Moreover, a pneumatic tapping system is known in the prior art which closes the metallurgical container from the exterior. However, this entails a great splashing risk.
From German patent DE 33 27 671 a device for a substantially slag-free tapping of the molten mass of metal, in particular, of molten mass of steel, from metallurgical containers is also known. This document concerns primarily the object of preventing turbulence generation during an immersion process of a closing member and thus a mixing of the slag and the molten mass. For this purpose, a closing member is suggested which can be moved by means of a liftable and lowerable rod via a lifting system into the metallurgical container. The lowering of the flow member and its securing shortly above the bottom of the container above the tap opening results in a better binding of the negative potential turbulences. It is described that the type of flow member for reducing turbulence can also be completely lowered into the tap opening at the container bottom in order to thus terminate the tapping. However, when doing so, the flow member is not completely received by the tap opening but is seated on the opening. In all of the aforementioned tapping methods of the prior art only a slag-poor, but not a slag-free, tapping is possible. This means, inter alia, that the oxygen contents in the molten mass is increased by the entrained oxide slag which entails an increased deoxidation. The oxygen contents of the FeO in the slag makes the desulfurization and degassing more difficult.
Finally, from EP 0 315 311 B1 a plug for closing the tap opening in metallurgical containers is known. This plug is comprised of a cylindrically shaped container of metal which at its ends is provided with two plates. The end which is facing into the interior of the container for mounting of the container and the corresponding inner plate are arranged so as to be spaced by a gap relative to one another. The metallic container receives refractory material such as, for example, sand. This sand is enclosed by a plastic foil. The plug is provided with a plunger with which, after placing the plug into the tap hole, it is achieved that the outer plate is moved against the inner plate along a linkage which penetrates the sand mass. Accordingly, the plastic foil is torn. This process is enhanced by an edge area of the container provided with teeth. The sand exits from the gap and flows into the intermediate space between container and outflow opening and thus provides a sealing connection. Subsequently, the plunger is removed while the metallic container remains within the tap hole.
SUMMARY OF THE INVENTION
The present invention has accordingly the object to provide a method and a tapping system with which in a simple and inexpensive way a slag-free tapping of a metallurgical container can be performed so that steels of a high degree of purity can be produced.
This object is solved according to the invention in regard to the method by controlling the time of introduction of the plug which comprises a plug sleeve as well as a core of a refractory flowable material, closing off the tap opening from the exterior of the container, and changing the consistency and/or shape of the plug sleeve by temperature action such that the flowable material is distributed in the tap opening in a sealing fashion and in regard to the device in that the plug comprises a plug sleeve fitting the tab opening as well as a core of a refractory flowable material, that the plug sleeve itself is comprised of a material which is resistant relative to the molten mass of metal only for a short period of time with respect to its consistency and/or shape.
The core of the invention is the provision of a tapping plug system with which the tap opening of a metallurgical container can be optimally sealed. This is achieved according to the invention by a special configuration of the plug. According to the method of the invention it is suggested to control the time of introduction of the plug into the tap opening, for example, as a function of the weight of the tapped steel, of the bath level, or by means of a slag detection system. Preferably, automatic but also semiautomatic or manual controls are possible. The time of introduction can be controlled point-by-point or, for example, by means of a signal which is determined by means of visual sensing or by means of a monitor indicator.
SUMMARY OF THE INVENTION
The present invention has accordingly the object to provide a method and a tapping system with which in a simple and inexpensive way a slag-free tapping of a metallurgical container can be performed so that steels of a high degree of purity can be produced.
This object is solved according to the invention in regard to the method by controlling the time of introduction of the plug which comprises a plug sleeve as well as a core of a refractory flowable material, closing off the tap opening from the exterior of the container, and changing the consistency and/or shape of the plug sleeve by temperature action such that the flowable material is distributed in the tap opening in a sealing fas
Pleschiutschnigg Fritz-Peter
Wu Wei-Ping
Kueffner Friedrich
SMS Demag Aktiengesellschaft
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