EP0043338B1 - Gas-permeable body of fire-resistant material - Google Patents

Description

The invention relates to refractory, gas-permeable structures for blowing a gas into a metal treatment vessel through its lining.

The oxygen-blowing processes used to fresh iron, which are known under the names “LD”, “LDAC”, “OLP”, and “BOF” processes, have recently been improved in terms of metallurgy in such a way that secondary gases such as Nitrogen or argon, can be injected in a controlled manner. In other metal treatment vessels, such as pans for post-treatment of steel or electric arc furnaces, the blowing of gas into the metal bath through the vessel bottom or the lining of the vessel walls can also be considered.

The gas-permeable refractory bricks to be inserted into the lining of the base or the side walls of the vessel, through which the gas is introduced, are required to have a durability which corresponds to that of the other refractory lining, since a replacement of worn-out gas bubbles in the hot state, for example in the case of a converter base is difficult. Furthermore, the introduction of gas should be possible both continuously and in particular discontinuously; i.e. the vessel should also be able to be operated without introducing gas and, after the gas supply has been switched on again, the stones should be permeable to gas in an unchanged manner. In addition, the gas permeability of the stones over their service life, i.e. over an entire kiln trip, remain essentially the same.

The previously known gas-permeable stones made of porous refractory material do not meet these requirements. Their shelf life in fresh containers is much lower than that of the surrounding lining material. Porous stones installed in an oxygen converter in the floor can withstand less than 100 batches, while the rest of the lining provides a shelf life of 500 batches and more. Furthermore, a discontinuous gas supply is not possible with porous stones; metal penetrates into the pores of the stones and solidifies there. When the gas supply is switched on again, the stone is no longer sufficiently gas permeable.

In the earlier patent application EP-A1-0 021 861, the applicant has shown a device for blowing a treatment gas into a metal bath intended for insertion into the bottom of a metal treatment vessel, which has a noticeably improved durability compared to the previously known gas-permeable stones and the blowing in of the desired ones Amounts of gas allowed. This device essentially consists of a refractory, gas-permeable structure, wherein a plurality of flat, corrugated, tubular or wire-shaped metallic separating members of small wall thickness are embedded in the refractory material in the axial direction. According to one embodiment, this refractory, gas-permeable structure consists of at least two segments of refractory, non-porous material lying alongside one another on longitudinal surfaces, and metal layers arranged between them, the segments being combined on the long side by a common metal housing which is sealed on the longitudinal surfaces of the segments, possibly underneath Use of an intermediate mortar layer, and one of the end faces of the structure is provided with at least one connection and a distribution space for the gas supply.

To manufacture such structures, a prefabricated block of refractory material has to be cut into the required strips or segments, which is a very complex manufacturing step. Since the segments generally have a small thickness and a large length, segments produced by pressing refractory material are not sufficiently manageable and warp if they are subjected to a stone fire.

An object of the invention is to improve the structure of such structures in such a way that simplified production is possible and prefabricated segments with sufficient stability can be used.

Another task is to increase the gas throughput capacity without compromising the good durability of the structure.

These objects are achieved according to the invention in that the metal layers are pressed with the refractory material of the segments, at least one of the adjacent longitudinal surfaces of the segments being provided with a metal layer.

The arrangement of pressed-in metal supports makes the manufacture and handling of relatively thin segments of great length considerably easier, since the metal support acts as a kind of reinforcement for the segments, which increases their stability. The use of segments or partial bodies with pressed-in metal supports also simplifies the assembly of several segments to form a single building structure, since it is now unnecessary to insert sheet metal plates. Nevertheless, pairs of metal plates can be arranged between the segments if desired.

The structures according to the invention can be designed in such a way that the adjoining longitudinal surfaces of the segments are formed with a smooth or with a profiled, for example corrugated or grooved surface, and also in such a way that the segments with the interposition of metal plates, pairs of metal plates and / or spacers, lie together. The latter can be made from beads or knobs formed in the metal layers, from sheet metal strips, wires or from combustible or vaporizable inserts and the like. consist. A further embodiment can consist in the fact that a second support, For example, a sheet metal plate is attached, for example welded, and that the adjacent longitudinal surface of the neighboring segment is free of metal layers.

The profiles, such as shafts, grooves, grooves or the like, can be formed in the longitudinal surfaces of the prefabricated segments made of refractory material by cutting or milling. However, it is also possible to form the profiles in the course of the production of the segments, in that the press die or the mold wall of the press mold used for producing the segments is equipped with the corresponding negative profile, as a result of which the profile is formed in the longitudinal surfaces when the segments are pressed.

The segments with co-pressed metal supports with a profiled surface can be produced in a simple manner in that the press ram or the mold wall with the corresponding profiling, e.g. B. corrugation or scoring is provided and an initially flat sheet metal plate and the refractory mass are introduced into the mold. During the pressing process, the profiling is then automatically formed in the pressed sheet metal plate.

When assembling the segments provided with profiled metal supports, joints, channels are created in the structure through which the gas can pass, the profiled longitudinal surfaces being able to rest against both a smooth and a profiled longitudinal surface of the neighboring segment. The adjacent longitudinal surface of the neighboring segment can in turn be provided with a pressed-on metal support or it can be free of supports.

A further embodiment of the structure according to the invention can consist in that at least one co-pressed pair of metal inserts, e.g. Sheet metal, is embedded. Spacers of the type mentioned above can be arranged between the metal plates of a pair of inserts. The extent of the gas permeability can be varied further by the number of insert pairs arranged in a structure and by their configuration with spacers.

In the case of these co-pressed insert pairs, the structure can be produced in a simple manner by first introducing part of the refractory material into the press mold, then inserting the insert pair, which extends over the entire length of the stone but only over part of the stone width, and finally further refractory Material is filled. If the structure is to have more than one pair of inserts, this process is repeated accordingly. The pressing pressure is then applied perpendicular to the inserts and the structure is thereby shaped. After removal from the press, the inserts on the front of the structure are exposed to allow gas to pass through. Instead of a pair of plates, a folded sheet or a compressed pipe can also be used. Multi-layer inserts, possibly with spacer elements, are also possible.

The extent of the gas permeability can be varied by the number of insert pairs arranged in a structure. Since the refractory material used for the building structure can correspond to that of the rest of the lining, the building structure has the same durability as the lining surrounding it. An early renewal of the gas passage stones is not necessary.

As has been shown, the structures can also be operated without gas supply. While some metal penetrates into the narrow gap between the inserts of a couple, when the gas supply line is switched on again, this penetrated metal is flushed out of the structure and the original gas permeability is restored. This remains essentially the same over the entire service life of the structure.

• Die Fig. 1 eine erste mögliche Ausführungsform eines Baukörpers;
• die Fig. bis 7 verschiedene Ausführungsformen von Segmenten;
• die Fig. 8 ein Ausführungsbeispiel eines mitzuverpressenden Einlagenpaares im vergrösserten Massstab;
• die Fig. 9 eine zweite mögliche Ausführungsform eines Baukörpers in dem Segmente gemäss der Fig. 6 zur Anwendung kommen und
• die Fig. 10 eine dritte mögliche Form, in der Segmente gemäss der Fig. 7 eingesetzt sind.

The drawings serve to explain the invention in more detail, in which some possible configurations of the structures according to the invention are shown in a non-restrictive manner. Show it:

• 1 shows a first possible embodiment of a building structure;
• to 7 different embodiments of segments;
• 8 shows an embodiment of a pair of inserts to be pressed in on an enlarged scale;
• 9 shows a second possible embodiment of a structure in which segments according to FIG. 6 are used and
• FIG. 10 shows a third possible form in which segments according to FIG. 7 are used.

The structure 1 shown in Fig. 1 has a e.g. Metal housing 2 constructed from welded plates, which surrounds a total of twelve segments 3, which are arranged in two rows of six pieces each. Each segment 3 has a co-pressed metal support 4 and lies with an unreinforced side surface with the interposition of a mortar layer, not shown, close to the inside of the metal housing 2. This prevents the undesirable, because uncontrollable, gas flow along the metal housing.

A sheet metal plate 5 is inserted between the two rows of the segments 3, along which a gas passage can take place, as well as along the metal supports 4 of the segments 3. Instead of the sheet metal plate 5, a pair of plates can also be arranged. Furthermore, the sheet metal plate 5 or the pair of plates can be mortared.

The segments 3 are spaced from the end face of the metal housing by means of two strips 6, which are arranged on the inside of the metal housing 2 and are preferably attached to it by spot welding. On this side, which represents the cold side, an end plate 7 is welded tight, which is provided with a pipe connection 8. The one between the front plate te 7 and the end faces of the segments 3 remaining space is the distribution space for the gas.

The opposite side of the front side 7, not visible, represents the fire side of the building and can be closed with a cover plate. The latter is used if the infeed of the metal treatment vessel surrounding the structure contains tar or similar carbon carriers. It then serves to prevent the penetration of tar or the like into the gas passage joints of the structure and the sticking of the same during the heating of the vessel. The cover plate melts at the start of operation and releases the joints. In the area of the fire-side end face of the structure, a bracket (not shown) can be attached, via which the structure can be hung on a crane hook.

2, 3, 4, segments 30, 31, 32 are shown, which are provided on two, three and four longitudinal surfaces with co-pressed metal supports 4, 41, 42. The latter can be provided with punched claws 9 projecting into the refractory material for better connection to the refractory material. The segment 33 in FIG. 5 has a co-pressed metal support 4 and a second metal support 43 fastened to it by spot welding. The segments 30, 31, 32, 33 can be inserted into the structure according to FIG. 1 instead of the segments 3.

The Fig. Shows a segment 34 which is pressed on a longitudinal surface with a profiled and that a corrugated metal pad 44 and on the opposite longitudinal surface with a flat metal pad 4. When assembling two such segments 34 in a structure along the profiling channels for the Gas passage.

FIG. 7 shows a segment 35 which can replace three segments 3 of the structure according to FIG. 1. This segment 35 is provided with a U-shaped co-pressed metal support 45 and two pairs of sheet metal inserts 10, which extend over the entire length but only over part of the width of the segment 35. Depending on the desired gas permeability, these inserts 10 can be designed as smooth sheet metal strips or, as shown in FIG. 8, as sheet metal strips provided with spacers, such as sikken or grooves 11. To improve the connection between the stone mass and the inserts 10, these can be provided with claws 9.

The structure 1 shown in FIG. 9 has a metal housing 2 which surrounds twelve segments which are arranged in two rows of six pieces each. Each segment is provided with a profile on a longitudinal surface, specifically a profile in the form of grooves in the upper segments 34a and one in the form of waves in the lower segments 34. In practice, however, the same type of profiling will be used for all segments.

The pressed flat sheet metal plates, which are located in the joints between two segments of a row, can also be provided with profiles in one variant. An insert in the form of a pair of sheet metal plates is shown between the two rows.

The building body 1 shown in FIG. 10 has a metal housing 2 which surrounds four segments 35. These four segments lie against one another with their U-shaped pressed-in metal supports 45, whereas the unreinforced long sides of the segments lie against the inside of the housing, which e.g. is made from welded plates.

Sheet metal is particularly suitable as the material for the metallic inserts, e.g. in a thickness between 0.5 and 3 mm, which can optionally be provided with a surface protection.

The structure can, for. B. from a tar-bound magnesia mass with the following composition and the following grain structure:

4% by weight of coal tar pitch are added to the sintered magnesia as a binder. Other tars, pitches, synthetic resins or the like also come as binders. into consideration.

Another composition suitable for use in a building structure according to the invention has the following composition and the following grain structure:

Grain sizes

For chemical bonding, the components are mixed with 3.7% by weight of kieserite solution with a density of 1.22 g / cm ³ .

However, the invention is not restricted to the use of the refractory materials mentioned. Other refractory materials, e.g. B. Mixtures of magnesia and chrome ore, high alumina material can be used.

The structures according to the invention have sufficient gas permeability, the passage of gas taking place on the one hand through the joints between the individual segments and on the other hand through the joints between the metal inserts. The segments themselves have practically no gas permeability, and therefore the refractory material used for the structure can correspond to that of the rest of the lining of the metal treatment vessel. As a result, the gas-permeable structures have the same durability as that of the lining surrounding them, and premature renewal of the gas-permeable structures is not necessary. According to the invention, a metal plate is generally provided in each joint of the structure through which gas is to pass, whether in the form of metal layers on the segments or in the form of metal plates arranged between the segments. As said, these metal plates or supports prevent the penetration of metal from the metal bath of the treatment vessel into the joints, even in the case of the treatment of pig iron, which due to its consistency and viscosity has a particularly strong tendency to penetrate into the joints.

This phenomenon may be explained by the fact that the metal plates arranged in the gas-permeable joints exert a cooling effect and quickly dissipate the heat to the cold end face of the structure. As a result, penetrating treatment metal solidifies after a short distance (a few cm). In the case of joints without metal plates or coverings, however, the penetration of treatment metal up to the cold end face was observed.

Claims (9)

1. Refractory gas-permeable structural unit (1) for blowing gas into a metallurgical vessel through its lining, comprising at least two elements (3, 30, 31, 32, 33, 34, 34a, 35) composed of refractory non-porous material, said elements abutting against one another with their longitudinal faces and possibly with metal layers (4, 41, 42, 43, 44, 45) that are arranged between said elements, a common metal housing (2) sealingly surrounding the longitudinal faces of said elements if required by using a mortar interlayer, and at one of the end faces of the unit at least one gas-connection (8) and a gas distribution chamber, characterized in that the metal layers (4, 41, 42, 43, 44, 45) and the refractory material of the elements (3, 30, 31, 32, 33, 34, 34a, 35) have been brought together by pressing, at least one of the abutting longitudinal faces of the elements being provided with a metal layer.

2. Structural unit as defined in claim 1, characterized in that the metal layer arranged on one of the longitudinal faces of the elements comprises an additional metal layer (43) which may be fixed thereon by welding, the abutting longitudinal face of the neighbouring element being free from any metal layer.

3. Structural unit as defined in claims 1 or 2, characterized in that at least one pair of metal layers (10) abutting against one another is embedded in the elements, said layers and the refractory material having been brought together by pressing.

4. Structural unit as defined in claim 3, characterized in that spacing members, for instance wires or metal strips, are provided between the abutting metal layers of one pair.

5. Structural unit as defined in claim 3, characterized in that the distance between the abutting metal layers (10) of one pair is adjusted by beads or grooves (11) in the metal layers.

6. Structural unit as defined in claim 1, characterized in that at least one of the metal layers is provided with claws (9).

7. Structural unit as defined in claim 1, characterized in that the refractory non-porous material is profiled, for instance provided with grooves or corrugations.

8. Structural unit as defined in claim 1, characterized in that the metal layers are profiled, for instance provided with corrugations.

9. Structural unit as defined in claim 1, characterized in that the metal layers are made of steel sheets having a thickness from 0,5 to 3 mm.

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