SYSTEM FOR TREATING A REFRACTORY BATCH, USE OF SUCH A SYSTEM, METHOD FOR TREATING A REFRACTORY BATCH, AND USE OF A MOULD

Abstract

The invention relates to a system for treating a refractory batch, a use of the system, a method for treating a refractory batch, and a use of a mould.

Claims

1. A system for treating a refractory batch, comprising the following features: 1.1 a mould (2), comprising the following features: 1.1.1 the mould (2) is designed to receive a refractory batch; 1.1.2 the mould (2) consists at least in part of moisture-permeable material (4); 1.1.3 the material (4) is flammable; 1.1.4 the ignition temperature of the material (4) is less than 500 C.; 1.2 a refractory batch (3), which is received in the mould (2); 1.3 at least one portion which, as considered over the cross-sectional area of the system, consists exclusively of moisture-permeable material (4) and refractory batch (3).

2. The system according to claim 1, in which the material (4) consists of cardboard.

3. The system according to claim 2, in which the cardboard comprises a plastics coating at least in part.

4. The system according to claim 1 comprising a refractory batch (3) for producing a refractory shaped functional product in the form of a monoblock stopper, a ladle shroud, or a submerged nozzle.

5. The system according to claim 1, in which the batch (3) received in the mould (2) is a green body for producing monoblock stoppers.

6. A method comprising: treating a batch for producing a refractory shaped functional product in the form of a monoblock stopper, a ladle shroud, or a submerged nozzle, wherein the batch is treated using a system having the following features: a mould (2), comprising the following features: the mould (2) is designed to receive a refractory batch; the mould (2) consists at least in part of moisture-permeable material (4); the material (4) is flammable; the ignition temperature of the material (4) is less than 500 C.; a refractory batch (3), which is received in the mould (2); at least one portion which, as considered over the cross-sectional area of the system, consists exclusively of moisture-permeable material (4) and refractory batch (3).

7. A method for treating a refractory batch comprising the following steps: providing a mould, the mould having the following features: the mould (2) is designed to receive a refractory batch; the mould (2) consists at least in part of moisture-permeable material (4); the material (4) is flammable; the ignition temperature of the material (4) is less than 500 C.; introducing a refractory batch into the mould; leaving the refractory batch to dry in the mould.

8. The method according to claim 7, comprising the following further steps: arranging at least part of the mould at the site of use of a refractory ceramic product producible from the refractory batch; exposing the mould arranged at the site of use to heat in order to produce a refractory ceramic product from the refractory batch.

9. A method comprising: using a mould to receive a refractory batch, the mould comprising the following features: 9.1 the mould is designed to receive the refractory batch; 9.2 the mould consists at least in part of moisture-permeable material.

Description

[0079] FIGS. 1 and 2 serve to visualise the exemplary embodiments.

[0080] Said figures show, in a heavily schematised manner:

[0081] FIG. 1 a first exemplary embodiment of a system for treating a batch for producing a monoblock stopper in a lateral sectional view, and

[0082] FIG. 2 a second exemplary embodiment of a system for treating a batch for producing a monoblock stopper in a side sectional view.

[0083] The system 1 according to FIG. 1 comprises a mould 2 and a refractory batch 3 received in the mould 2.

[0084] The mould 2 comprises a circular-cylindrical tube 4 made of cardboard and a first closure 5 and a second closure 6, which are each made of steel. The tube 4 is disposed in FIG. 1 in an upright position, that is to say with a vertically extending longitudinal axis L of the tube 4. The tube 4 is closed at its lower end 4u by the first closure 5 and at its upper end 4o by the second closure 6.

[0085] The tube 4 of the mould 2 is formed from a cardboard shaped in a circular-cylindrical manner with a clear diameter of 131 mm. The wall thickness of the cardboard is 3 mm. The length of the tube 4 is 1,590 mm, wherein the length of the tube 4 in the illustration according to FIG. 1indicated by the dashed lines 7 with a zigzag coursehas been shown shortened. The tube 4 encloses an interior 4h inside the tube 4. The cardboard from which the tube 4 is made is moisture-permeable hard paper, which is glued to itself in a number of layers. The grammage of the cardboard of the tube 4 is 2.13 kg/m.sup.2.

[0086] At its lower end 4u, the tube 4 is tightly closed by the first closure 5. To this end, the first closure 5 comprises a portion 5.1, which is inserted into the lower end 4u of the tube 4. Here, the portion 5.1 has a circular-cylindrical outer circumference with a diameter corresponding to the clear diameter of the tube 4, such that the tube 4 at its lower end 4u bears with its inner wall flat against the circumference of the portion 5.1 of the first closure 5. The portion 5.1 of the first closure 5 is adjoined by a second portion 5.2, which protrudes circumferentially beyond the first portion 5.1 and hereby forms a contact edge 5.3, against which the tube 5 abuts with its lower end face. On the side 5.4 of the first closure 5 facing away from the tube 4, a metal base plate 8 is screwed against the first closure 5. The base plate 8 is disc-shaped and has a diameter of 300 mm. The mould 2 can be placed securely on a substrate via the base plate 8.

[0087] On its side facing towards the cavity 4h of the tube 4, the first attachment 5 has a shell-shaped recess 5.5, which extends concavely into the portion 5.1.

[0088] The second closure 6 is composed in a number of parts from individual steel elements. The second closure 6 has a first portion 6.1, which is inserted into the upper, end-face portion 4o of the tube 4. Similarly to the portion 5.1 of the first closure 5, the first portion 6.1 of the second closure 6 also has a circular-cylindrical outer circumference with a diameter corresponding to the clear diameter of the tube 4, such that the tube 4 at its upper end 4o bears flat via its inner wall against the circumference of the portion 6.1 of the second closure 6. The first portion 6.1 is adjoined by a second portion 6.2 of the second closure 6, which protrudes beyond the first portion 6.1 at the outer circumference thereof. Here, the second portion 6.2 forms contact edges 6.3, against which the tube 4 abuts via its upper end face. The second closure 6 has a bore concentric with the longitudinal axis L of the tube 4, which bore comprises three portions 9.1, 9.2 and 9.3 with different diameters. Here, the first portion 9.1 of the bore 9 with the largest diameter is arranged on the side facing towards the interior 4h of the tube 4 and the portion 9.3 of the bore 9 with an average diameter is arranged in the second closure 6 on the side facing away from the interior 4h of the tube 4. The portion 9.2 of the bore 9 with the smallest diameter extends between these two portions 9.1 and 9.3.

[0089] The closure 6 is also used in particular for positioning a nut that can be formed in the refractory batch 3 and into which a rod can be screwed (indicated by the dashed line 10), via which a monoblock stopper producible from the refractory batch 3 can be held and moved during its later use at the tundish.

[0090] The inner wall of the interior 4h of the tube 4 which is not filled by the first and second closure 5, 6, the surface of the shell-shaped recess 5.5 of the first closure 5, the surface portions of the second closure 6 facing towards the interior 4h of the tube 4, and the surface of the bore 9 form a cavity H in the mould 2.

[0091] The cavity H is filled fully with the batch 3. The refractory batch 3 is a refractory casting compound for producing a carbon-bonded refractory ceramic functional product in the form of a monoblock stopper. The refractory batch 3 is composed of 82.5 mass % fused magnesia, 12 mass % graphite, 3.0 mass % binder, 2.0 mass % antioxidant, and 0.5 mass % silicon dioxide powder, in each case in relation to the total mass of the batch 3. The fused magnesia is provided in a purity of 97 mass % MgO. The graphite, as carbon carrier of the refractory batch 3, comprises a proportion of carbon of 94 mass %. The binders are a mixture of novolac and pitch. Aluminium powder is provided as antioxidant. This results in a mass proportion of MgO in the batch of approximately 80.0 mass % and a proportion of carbon in the refractory batch 3 of approximately 11.3 mass %, in each case in relation to the total mass of the refractory batch 3.

[0092] The refractory batch 3 was filled into the cavity H through the bore 9 in the second closure 6, until it completely filled the cavity H. The mould 2 was then shaken, such that the refractory batch 3 settled further and compacted.

[0093] The factory batch 3 was then left to dry in the mould 2. During drying, moist components of the refractory batch 3 diffused through the moisture-permeable tube 4 outwardly and evaporated on the surface of the tube 4 exposed to the surrounding environment U. Further moist components of the refractory batch 3 evaporated through the bore 9. This diffusion and evaporation continued until the refractory batch 3 was completely dry. A green body shaped by the mould 2 and formed from the refractory batch 3 for producing a carbon-bonded monoblock stopper was then obtained.

[0094] Since the first closure 5 and the second closure 6 are not flammable parts of the mould 2, the first closure 5 and the second closure 6 were removed from the mould 2 and the refractory batch 3 following the drying of the refractory batch 3. In spite of the undercut of the refractory batch 3 in its portion formed by the bore 9, the removal of the second closure 6 from the batch was possible due to the multi-part nature of the closure 6.

[0095] As shown clearly in FIG. 1, the mould 2 consists of moisture-permeable material in the form of the tube 4 made of cardboard from the upper edge of the first closure 5 to the lower edge of the second closure 6. This portion of the mould 2 is denoted by reference sign A. Furthermore, along the portion A1 (which extends from the upper edge of the first closure 5 to the lower edge of the nut 10 formed in the refractory batch 3) of this portion A, the batch 3 extends over the entire cross-sectional area of the mould 3. The system 1, as considered over any cross-sectional area of the system 1 along this portion A1, thus consists exclusively of moisture-permeable material in the form of the tube 4 made of cardboard and refractory batch 3. In this portion A1, a cross-section can be taken through the system 1, wherein this cross-sectional area is fully encompassed at the edge by the cardboard of the tube 4. An example of a cross-section of this kind is shown by the cross-section along the sectional area Q-Q.

[0096] As mentioned before, the batch 3 of the system 1 constitutes a green body for producing a monoblock stopper, which can be fired without further shaping to form a monoblock stopper. This monoblock stopper, which can be fired from the batch 3, extends along a longitudinal axis corresponding to the longitudinal axis L of the tube 4 and at the same time also the longitudinal axis L of the batch 3 or of the green body formed from the batch 3 once said batch has dried. Along the portion A1, the system 1, as considered over a cross-sectional area intersecting this longitudinal axis L at right angles, consists exclusively of moisture-permeable material in the form of the cardboard of the tube 4 and refractory batch 3. Here, the system 1 consists to an extent of significantly more than 50% of the length of the longitudinal axis L, as considered over the cross-sectional area of the system 1, exclusively of moisture-permeable material in the form of the cardboard of the tube 4 and refractory batch 3.

[0097] The system according to FIG. 2 is largely identical to the system according to FIG. 1, and therefore the matching components of both systems have been provided with the same reference signs.

[0098] In contrast to the system 1 according to FIG. 1, however, the system 1 according to FIG. 2 also comprises a tube 11, which is arranged coaxially with the longitudinal axis L of the tube 4 or coaxially with the longitudinal axis L of the green body in the mould 2 formed from the batch 3. The tube 11 is formed from the same cardboard from which the tube 4 is also formed. The tube 11 has a clear diameter of approximately 10 mm. In the system 1 according to FIG. 2 the region of the cavity H occupied by the tube 11 is not filled with the batch 3.

[0099] In order to produce the monoblock stopper from the dried, shaped refractory batch 3 of the systems 1 according to FIGS. 1 and 2, the mould 2 or the tube 4 of the mould 2 with the batch 3 received therein remaining once the first and second closures 5, 6 have been removed is arranged at the site of use of the monoblock stopper producible from the refractory batch 3 in the tundish of a continuous casting system. A rod for later holding and moving of the monoblock stopper was firstly screwed into the nut formed in the refractory batch 3, and the mould 2 was exposed to heat by heating the tundish. Once the ignition temperature of the cardboard of the tube 4 of approximately 360 Celsius was reached, the cardboard ignited and burned off fully; in the system 1 according to FIG. 2, once the ignition temperature of the cardboard of the tube 11 had been reached, this cardboard also ignited and likewise burned off fully. Following further heating of the tundish, a carbon-bonded monoblock stopper was ultimately produced from the refractory batch 3. In the system 1 according to FIG. 2 the space initially taken up by the tube 11 in this case formed a gas channel for introducing gas into the formed monoblock stopper.