DE60205350T2 - FIRE-RESISTANT CONSTRUCTION BODY OR STONE FOR BLOWING GAS IN MELTED METALS - Google Patents

Description

The The present invention relates to a refractory plug or refractory tile for one Case lining for injecting gas into molten metal, as well as the production a refractory plug or refractory brick for injecting Gas in molten metal.

gases become common for various purposes in molten metal in containers, such as ladles, Crucibles or intermediate containers injected. For example, a gas may be supplied to the lower part of a container, around the relatively cool Soil area of solidification products, e.g. around her from the neighborhood of a lower pouring outlet where the container having such an outlet. For example, in steelmaking the use of a slow injection of a fine curtain of Gas bubbles in the distributor tank to eliminate inclusions at; the inclusions are attracted to the small gas bubbles and go through the melt is up to the surface where it is in conventional Way from the intermediate container cover powder or flux are captured. Gas can also be supplied to rinse the melt or to homogenize thermally or in terms of their composition, or to help add alloying additives over the melt to distribute.

Usually will used an inert gas, however, can reactive gases may also be used, e.g. reducing or oxidizing Gases when the melt compositions or components thereof a change require. For example, it is common Gases, such as nitrogen, chlorine, freon, sulfur hexafluoride, argon and to inject such into molten metal, for example in molten aluminum or molten aluminum alloys, around unwanted Ingredients, such as hydrogen gas, non-metallic inclusions and To remove alkali metals. The added to the molten metal reactive gases chemically react with the undesired constituents around them into a mold, such as a precipitate, a metal slag or an insoluble one Convert gas, which readily from the rest of the melt can be separated. These gases (or others) could also be together, for example used with steel, copper, iron, magnesium or alloys thereof become.

Around to carry out a gas injection process efficiently, it is desirable that the gas, preferably from the bottom of the vessel, in the form of a very huge Number of extremely small ones Bubbles in the molten metal is supplied. With decreasing gas bubble size decreases the number of bubbles per unit volume. An increase in the number of bubbles and their surface per unit volume increases the probability that the injected Gas is used efficiently to carry out the desired process.

Have previous gas injection suggestions the installation of a solid porous Refractory plug or refractory tile in the refractory lining of the container enclosed, generally on the floor, but also in the walls. in the Use lead the plugs or bricks to a gas flow in the form of bubbles.

To the Example is a known technique (GB-A-2096290) for feeding Gas in molten metal in it, part of a molten one Metal containing container (preferably the bottom of the container) with a porous one ceramic body undress. The gas is supplied into the porous body at a position that from the in contact with the metal standing surface of the body is removed. During his passage through the body The gas follows a series of small tortuous paths, leaving one size Number of bubbles is discharged into the molten metal.

in the Generally supports a metal case, that as a distributor for feeding of gas in the body serves, the porous one Ceramic body. Typically, the housing made of weldable Steel (for use with inert or poorly reactive gas, such as Argon or nitrogen) or Inconel (for use with extremely reactive Chlorine or freon). The composite body / housing is on all sides except at its top of refractory material, such as alumina casting compound with low cement content or bricks, surrounded and supported. If casting This can be used either in situ around the porous body be cast or formed from precast components, the while the installation of the liner of the hot metal container in place be attached. The lining material will "rest" against the porous body structure.

A problem with the foregoing construction is that it is difficult to maintain an effective gas seal between the housing and the body, as well as between the housing and the supporting puddle (s). A difficulty arises partly because the heat coefficients of the metal housing and refractories are quite different; Also, the metal housing is exposed to attack when chlorine is the gas used. If a crack were to develop (as used herein, the term "crack" designates any defect in the gas distribution device that allows for undesirable gas leakage), gas will escape through the crack and will thereafter be frequently passed through the next brick and Hiking refractory support in the surrounding atmosphere. Gas migration through 50 cm or more refractory material is possible. The problem is undesirable since the effect of gas leakage is that the gas flow through the intended gas bubble formation surface can be seriously reduced and the effectiveness of the bubble forming block can be reduced. In some cases, the gas stream will end up in the form of fine gas bubbles and be replaced by a gas stream of uncontrolled direction in the form of large ineffective gas bubbles. When argon is used, the relatively high cost must be taken into account. The problem is particularly acute in the case of chlorine, because of the harmful effects of chlorine after release to the atmosphere. Regardless of the type of refining gas used, it is important that cracks be prevented so as to prevent gas leakage.

It would be desirable that a technique for injecting gas into molten metal which would be available the specifications of distributing a large number of extremely small ones Bubbles in the molten metal would meet while at the same time cracks in the gas distribution device, which lead to a gas leak, avoided become.

It would be too desirable, that any such device at a reasonable cost and with smaller dimensions than the existing devices easily made can be.

Further would it be desirable, that any such gas injection device with existing equipment, such as an intermediate container, a ladle, a crucible and the like, without a change, or with only minor changes, at the existing equipment is usable.

Around this device into the existing refractory lining of the container for molten To use metal would be it further desirable that any such gas injection device with the surrounding Refractory materials compatible is to any harmful chemical reactions or thermal expansion intolerances to avoid.

Further would it be desirable, to provide a device that only by smaller Adjustments during of the manufacturing process to a very wide range of bubbling conditions (bubble size, volume, Pressure, etc.) could be adjusted so that the device can meet special customer requirements.

• i) einen porösen Feuerfestkörper, der im Wesentlichen außer an der Berührungsfläche zum geschmolzenen Metall von einem im Wesentlichen nicht-porösen Körper umgeben ist; und
• ii) eine Gasleiteinrichtung zum Fördern des Gases aus einer Gasquelle zu dem porösen Körper.

The invention thus relates to a solid porous refractory plug or tile for a container liner for injecting gas into molten metal through a molten metal contacting surface

• i) a porous refractory body substantially surrounded by a substantially non-porous body except at the molten metal contacting surface; and
• ii) a gas guide for conveying the gas from a gas source to the porous body.

Of the Plug or brick according to the invention is characterized in claim 1. The process for its preparation is specified in claim 7.

The US-A-4,791,978 and 4,836,508 which relate to a stopper rod and a pouring nozzle respectively, reveal jointly pressed refractory bodies, each dense and are porous, However, they do not relate to the problem of improving the Gas-tightness of a non-metallic permeable plug or brick, the a part of a container liner forms and the sole purpose of injecting gas for treatment of the molten metal in the tank Has.

in the Scope of the present description may be a plug or brick for one Container lining to Inject gas from a stopper, a brick, a block, a dam, a tile, a threshold and the like. As discussed above, can The plug or brick of the invention can be used to charge any gas (whether reactive or inert) into any molten metal or to inject an alloy thereof. The plug or brick has at least one contact surface for molten metal through which the gas is injected.

The plug or brick comprises a porous refractory which, except of course, touches the ground is substantially surrounded by (for example, enclosed by or embedded in) a non-porous body to the molten metal. It may be contained in or form part of the lining of the molten metal container.

Of the porous body can be made of any porous Refractory material exist. Indeed the type of material used is not material, provided that said material the desired porosity has. In general, a material that has an apparent porosity of more than 20 possesses, as porous considered. Suitable materials typically include alumina, Alumina spinel, magnesia or magnesia spinel, or combinations of any of the above.

Of the Plug or brick also includes a gas guide to the Gas from a gas source to promote the porous body. The gas guide generally includes a conduit that extends through the side wall of the non-porous body extends. This pipe can be made of metal or a refractory material, for example getting produced. The line can by means of a conventional Refractory sealing material (mortar or cement) can be fixed in place, or it can be placed in the nonporous body be pressed.

A Conventional gas guide can be used. However, since the tightness of the connection must be specially monitored special arrangements are particularly preferred, such as those which are disclosed in WO-A1-01 / 83138.

It is also advantageous in that the gas guide a distribution chamber by which the gas comes into contact with a surface of the porous body, at least substantially the contact surface with the molten metal corresponds so that the gas is distributed completely homogeneously in the porous body and consequently through substantially the entire interface to the molten metal will bubble into the molten metal.

These Type of plug or brick for injecting gas into molten one Metal is for example from USP 5,054,749, 5,423,521 or 5,219,514 known. However fulfilled none of these the above requirements.

Of the Plug or brick of the present invention is by the fact characterized in that the non-porous body of refractory material exists and that the porous one body and the non-porous Body together must be pressed. All the above requirements are met with such a plug or brick met.

Again is the type of non-porous Material not essential, as long as it is a refractory material and the desired porosity has. In general, a material that has an apparent porosity of less than 20%, as non-porous considered.

Of the nonporous body and the porous one body are preferably made of refractory materials with similar Thermal expansion coefficient educated. This serves to prevent the formation of cracks during thermal cycling to prevent.

By Use of the present invention may include granulometry and permeability of the inner porous body careful and be constantly controlled to ensure a uniform fine To provide pore structure, so that small, evenly distributed gas bubbles out the contact surface of the body pour to the molten metal. This permeability can through changes adapted to the granulometry of the preparation or recipe effortlessly and an inventive plug or bricks can be made to be specific individual Customer requirements met.

This Process way is further advantageous insofar as refractory materials high magnesium oxide content for The recipes can be used as magnesium oxide spinel. Such formulations are associated with the composition of steelworks tundish liners better tolerated, the usually basic ones (Magnesia) basis are. Chemical and thermal properties are therefore very similar. Advantageously, therefore, the porous and non-porous refractory have a high magnesium oxide content of more than 50%, preferably more than 80% and even better more than 90% by weight of the composition.

Accordingly, similar materials can be used for the porous and non-porous bodies, however be used with different granulometries. Thus, it is possible to produce a plug or brick of high magnesia content materials of the present invention having various granulometries.

thanks prevents the common pressing of the two refractory materials The natural low permeability the non-porous body gas leaks, without resorting to other techniques for limiting gas leaks got to. Another advantage of co-pressing is that a plug or brick for injecting gas of smaller overall dimensions can be used, the required degree of gas bubble formation achieved becomes. This facilitates the handling of this plug or brick while transport and installation in the container; especially in the lining.

The Concept of joint pressing is not on oblong, square, round or oval shapes, but can also be used to any refractory cross section to produce, which is suitable for common pressing. For example, can imagine a co-pressed component in the form of a ring, which would be arranged so that he has the outlet openings an intermediate container surrounds, creating a surrounding stream of gently rising bubbles is formed by the hot liquid metal before entering would have to pass into the continuous casting molds.

• 1) Zuführen von passenden Mengen der den porösen und den nicht-porösen Körper bildenden Feuerfestmaterialien in eine Form unter Beachtung der gewünschten Begrenzungen für diese Körper;
• 2) Gleichzeitiges gemeinsames Pressen beider Feuerfestmaterialien;
• 3) Bereitstellen einer Gasleiteinrichtung;
• 4) Wärmebehandeln der gemeinsam gepressten Materialien.

In another of its aspects, the invention relates to a method of making a plug or brick for injecting gas into molten metal. According to the invention, this method comprises the steps:

• 1) supplying appropriate amounts of the refractory materials constituting the porous and non-porous bodies into a mold, taking into account the desired limitations for these bodies;
• 2) simultaneous co-pressing of both refractory materials;
• 3) providing a gas guide device;
• 4) Heat treating the co-pressed materials.

Preferably will be before feeding of the refractory material a limit, for example, from a thin (but stiff) plastic or metal foil is in the mold posed. The boundary can be considered a cylinder (with circular or oval base) or shaped as a cuboid without top and bottom. The refractory material, that the porous one body is then formed in the middle formed by the boundary Part supplied, and the refractory material that is non-porous body will form is fed between the boundary and the mold wall. The Limitation is then carefully removed, and another set the material that forms the non-porous body, is fed into the mold, around to the contact surface to the to form molten metal opposite surface.

Of the Step of providing the gas guide may be before or after the step of co-pressing or both before and then executed become. In a preferred embodiment of the invention by introducing a strip of consumable material to the joint between the base area of the porous one body forming material and the adjacent surface of the non-porous body forming Material formed in the form of a distribution chamber.

alternative or additionally may be due to or before the common pressing of the materials through the non-porous body a hole is drilled through or a conduit is inserted, around the porous one body (whether through the distribution chamber or not) with an external one Gas source to connect.

Of the Step of common pressing can be done according to any carried out known compression method be, for example in a hydraulic press.

Of the Heat treatment step could carried out at a temperature be sufficient to make a ceramic connection between the porous and the non-porous body train so that the integrity of the plug or brick and its gas tightness can be improved. That for the production of Distribution chamber introduced consumable material (if used is) is advantageously during the heat treatment step away. This consumable material may be at the temperature used burn (cardboard, paper) or melt (wax, alloy). typically, is the heat treatment step in it, the co-pressed material at between 800 and 1800 ° C lying Temperature for 2 to 12 hours to burn.

The invention will now be better described with reference to the accompanying drawings, which are provided only for the purpose of illustrating the invention and not for limiting its scope be presented. 1 and 2 show cross-sectional views of embodiments of the invention.

Both figures show a plug or brick ( 1 ) for injecting gas into molten metal through a contact surface ( 11 ) to the molten metal comprising a porous refractory body ( 2 ), which is essentially except at the interface ( 11 ) to molten metal from a substantially non-porous body ( 9 ) is surrounded. In the 1 and 2 Also visible are the gas guiding devices, which are a metallic or refractory line ( 4 ), which extend through a wall ( 6 ) of the plug or brick and with the distribution chamber ( 3 ) connected is. The administration ( 4 ) is typically carried out by means of a conventional sealing cement or mortar ( 5 ) fixed in place.

Advantageously, during the pressing step, a to the contact surface ( 4 ) to the molten metal gradually tapered cross-section ( 7 ) generated. This tapering action is generated during the pressing operation as the porous body deforms on the vertical sides of the die into the non-porous medium. This rejuvenated shape protects the porous body ( 2 ) by forming a positive fit against a larger gap.

According to one Example of the invention, the materials used are the following: (% indicated by weight):

To the feeding into the mold, the materials have been mechanically pressed, and though at a speed to get the best possible compression and integration of the pressed materials. The heat treatment step it was accomplished, by slowly heating the co-pressed material to 1600 ° C, and at a speed to thermal breaks / cracks within the pressed body avoid using the stopper or tile for 4 hours at this Temperature was left and allowed to cool slowly.

The following properties have been measured:

in the Use the stopper or tile has fine bubbles and reliable constantly injected.

Claims (10)

Solid porous refractory plug or tile ( 1 ) for a container lining for injecting gas into molten metal through a contact surface ( 11 ) to the molten metal, comprising i) a porous refractory body ( 2 ), which is essentially except at the interface ( 11 ) to the molten metal in a substantially non-porous body ( 9 ) is included; and ii) a gas-conducting device ( 3 . 5 ) for conveying the gas from a gas source to the porous body ( 2 ), characterized in that the non-porous body ( 11 ) consists of refractory material and that the porous and the non-porous body ( 2 . 11 ) have been pressed together. Plug or brick according to claim 1, characterized in that the gas guiding device ( 3 . 5 ) a distribution chamber ( 3 ). Plug or brick according to claim 1 or 2, characterized characterized in that the porous and the non-porous body of refractory materials with similar ones Thermal expansion coefficient be formed. Plug or brick according to one of claims 1 to 3, characterized in that the porous and the non-porous body of more than 50% by weight of magnesia, magnesia spinel, alumina or Alumina spinel are formed, preferably of more than 80% by weight. Plug or brick according to one of claims 1 to 4, characterized in that the non-porous body is more than 50% by weight, preferably more than 80% by weight of magnesium oxide, magnesium oxide spinel, Alumina or alumina spinel. Plug or brick according to one of claims 1 to 5, characterized in that the porous body ( 2 ) in the direction of its contact surface with the molten metal toward a tapered cross section ( 7 ) having. Process for producing a solid porous refractory plug or bricks for a container liner for injecting gas into molten metal through a contact surface for molten metal, comprising the steps: 1) feeding from suitable amounts of the porous and the non-porous body forming refractory materials in a mold in compliance with desired Limits for these bodies; 2) Simultaneous co-pressing of both refractory materials; 3) Providing a gas conducting device; 4) heat treatment of co-pressed materials. Method according to Claim 7, in which the gas-conducting device comprises a distribution chamber. Method according to claim 8, characterized in that the step ( 3 ) of providing the gas guide means a step of introducing a strip of consumable material into the mold on the Collision between the porous and the non-porous body comprises. Method according to claim 9, characterized in that that the consumable material comprises wax.