GB2085133A - Refractory linings for metallurgical vessels - Google Patents

Abstract

A ladle or other metallurgical vessel having two linings 3, 5 of refractory brick is provided between them with an intermediate lining 4, made of sheets or slabs of refractory material, the surface area of the individual sheets or slabs being large in relation to the surface area of the individual bricks. The intermediate lining can be a single layer or it can be made of several layers. The abutting edges of the sheets or slabs can have wedge-shaped, step-shaped or other complementary forms. <IMAGE>

Description

SPECIFICATION Refractory linings for metallurgical vessels This invention relates to metallurgy and is con cerned especially with the construction of ladles and other metallurgical vessels. It is common practice, in many fields of metallurgy, to transport molten metal in a ladle, which consists essentially of a metal shell lined with refractory material, the shell usually consisting of a floor and an upstanding wall.

In the manufacture of steel, for example, molten metal is tapped from a furnace into a ladle which is positioned beneath the furnace taphole. The refractory lining adjacent the ladle floor and the lower part of the ladle wall becomes severely eroded in use by the impact of the molten metal.

The floor of the metal shell of a ladle is usually somewhat dished and it is common practice to provide, between the refractory lining and the floor of the metal shell, a layer of concrete, which thus provides a level foundation for the refractory lining. The lining is normally provided, both against the ladle wall and upon its floor, as a double refractory layer, consisting of an outer course or layer of lowrefractory material and an inner course or layer of high-refractory material. Thee outer layer, which makes direct contact with the metal shell or the concrete foundation of the ladle, is known as the safety lining. The inner layer, which makes direct contact with the molten metal, is known as the working lining. The blocks or bricks used to form the double refractory lining are commonly of a bloating type of fireclay.The double lining may be installed either wet or dry, i.e. with or without cement to hold the blocks or bricks in place. One reason for this principle of construction is to ensure that the severe erosion will occur mainly in the working lining, in the hope that only this refractory material need be replaced in due course.

As the ladle is heated in use, the refractory lining expands en masse. As the ladle subsequently cools, the bricks tend to contract individually, opening up the joints or cracks between the bricks. Cracking is worse if workmanship is bad. Molten metal enters the cracks and penetrates between the bricks ofthe working lining, ultimately penetrating between the bricks of the safety lining and bonding the two linings together when the metal solidifies upon cooling. Metal penetration is most likely where erosion and the impact of impinging metal are most severe.

Regular replacement of the lining is therefore necessary, because of the erosion ofthe lining at the floor and at the lower part of the wall. The entire lining may be replaced, but often is is only necessary to replace the eroded parts. Ideally, only the working lining would need to be replaced, but, because of the metal penetration referred to, it is usually not possible to strip the working lining away without tearing away the safety lining too. Consequently, the entire thickness of the refractory lining must be replaced, which involves considerable consumption oftime and materials.

It has now been found that a refractory-lined ladle or other form of metallurgical vessel can be constructed, which avoids these disadvantages and which also allows for rapid removal of the working lining when necessary, without damaging the safety course of brickwork, i.e. the safety lining. A lined metallurgical vessel according to this invention not only allows worn parts of the lining to be removed and replaced at minimum cost, but also reducesthe damaging effect of metal penetration into the lining.

According to the invention, a metallurgical vessel is provided, comprising a metal shell having a safety lining and a working lining, each comprising refractory bricks or blocks, wherein an intermediate lining is provided between the safety and working linings over at least part ofthe vessel, such intermediate lining comprising sheets or slabs which are large in comparison with the bricks or blocks of the safety and working linings.

In putting the invention into effect, the sheets or slabs constituting the intermediate lining may, for example, each have a size and shape so as to be at least twice as large in area as the individual bricks forming the safety and working linings. Since molten metal can penetrate the safety lining only at the joints between the sheets or slabs of the intermediate lining, the risk of stripping away the safety lining with the working lining is eliminated or at least substantially reduced.

The intermediate lining has the additional advantage that its inherent thermal insulating properties enhance the total thermal insulation provided by the composite refactory lining.

In order that the invention may be fully understood, a preferred embodiment is described below by way of example, in the form of a lined ladle for use in steel manufacture, in conjunction with the accompanyings drawing, showing part of the ladle in diagrammatic cross-sectional view.

A metallurgical vessel according to this invention shown as a ladle, has a metal shell of conventional form, having a curved or dished floor la and an inclined upstanding side wall 1b. Above the ladle floor la, a foundation layer 2 of concrete is provided, so that a flat surface is provided at the base of the shell. Against the flat surface of the concrete layer 2, the remaining peripheral region of the ladle floor 1a and its wall ib, an outer or safety lining 3 of lowrefractory material, e.g. bricks or blocks, is installed in the ladle 1. An inner or working lining 5 of highrefractory material, also in the form e.g. of bricks or blocks, is installed within the ladle 1, the exposed faces of the bricks or blocks forming the lining 5 constituting the inner metal-contacting surface of the ladle 1.In a conventional form of ladle, the working lining 5 is built against the safety lining 3, but in accordance with this invention, an intermediate lining 4 of refractory material is interposed between the safety lining 3 and the working lining 5, over at least part of the vessel 1. As shown in the embodiment illustrated, the intermediate lining 4 extends entirely The drawing(s) originally filed was/were informal and the print here reproduced is taken from a laterfiledformal copy.

overthe floor area of the ladle 1 and partly up the wall area. The intermediate lining 4 has an upper level 6 which may coincide with the top rim of the ladle 1 or, as shown in the drawing, may lie at a lower level part-way up the ladle wall 1b. In the latter form, the intermediate lining thus extends generally over the part of the ladle 1 which in use is most liable to metal penetration.

The intermediate lining 4 is preferably in the form of sheets or slabs which are large in comparison with the bricks or blocks forming the safety lining 3 and the working lining 5 and also may be made of any refractory material which can withstand satisfactorily the temperatures and pressures to which the intermediate lining 4 is subjected in use. The material may be siliceous, basic or neutral, of a particulate and/orfibrous nature, ceramically bonded together to form a coherent sheet, board or slab. Examples of binding agents for inclusion in the intermediate lining material are silicates, phosphates and organic binders.

The surface area of the individual refractory sheets or slabs forming the intermediate lining 4 preferably is large in comparison with the surface area of the individual bricks or blocks ofthe working lining 5 and the safety lining 3. For instance, each sheet or slab of intermediate lining material may extend over more than 2 and, for example, over 5 or 10 of the bricks or blocks of the other two linings. As already indicated, an important characteristic of the sheets or slabs forming the intermediate lining is that each of them is large in comparison with the bricks or blocks forming the two other linings. Though the sheets or slabs can be no more than twice as large, they can conveniently be much larger for instance each sheet or slab can in theory be any multiple of the size of each block or brick.In practice, very large sheets or slabs could be difficult to handle and a feasible upper limit for their size is, for instance, where each is say 16 or possibly 32 times the size of the bricks or blocks.

The intermediate lining 4 may comprise a single layer of abutting refractory sheets or slabs, as shown in the drawing. In another constructional form, it may comprise two or more layers of abutting refractory sheets or slabs. This latter embodiment has the advantage that the joints in each layer forming the intermediate lining 4 may be offset from the joints in the adjacent layer or layers, so as to provide an even more effective barrier against metal penetration.

The confronting edges ofthe abutting sheets or slabs forming the intermediate layer may advantageously overlap, to discourage metal penetration between them. The overlapping may be done by making the sheets or slabs so that their edges have a wedge-shaped or step-shaped profile, the profiles of abutting edges being complementary.

Although primarily concerned with ladles for molten steel, the invention is also applicable to other metallurgical vessels and to other molten metals.

For example, tundishes in the steel industry are usually lined with a single layer of refractory bricks, but large tundishes, which in use are subjected to particularly heavy stresses, can advantageously be lined with two layers of bricks, which are separated by an intermediate lining in accordance with the invention. Another possible application of the invetion is to vessels for molten metals such as aluminium, which are poured at a lower temperature than steel. With these metals, the intermediate lining is subjected to lower temperatures and the range of suitable materials for making the intermediate lining is correspondingly larger; suitable materials for such refractory intermediate linings include steel plate, for instance.

Claims (8)

1. A metallurgical vessel, comprising a metal shell having a safety lining and a working lining each comprising refractory bricks or blocks, wherein an intermediate lining is provided between the safety and working linings over at least part of the vessel, such intermediate lining comprising sheets or slabs which are large in comparison with the bricks or blocks of the safety and working linings.

2. A vessel according to claim 1, having a floor and a wall, wherein the intermediate lining extends between the safety and working linings overtheves- sel floor and the vessel wall.

3. A vessel according to claim 1 or 2, wherein the intermediate lining comprises a single layer of sheets or slabs.

4. Avessel according to claim 1 or 2, wherein the intermediate lining comprises two or more superposed layers of sheets or slabs.

5. A vessel according to any preceding claim, wherein the intermediate lining comprises sheets or slabs having interfitting or overlapping edges with complementary profiles.

6. A vessel according to any preceding claim, wherein the intermediate lining comprises a basic, neutral or siliceous bonded particulate and/or fibrous material.

7. A vessel according to any of claims 1 to 5, wherein the intermediate lining comprises steel plate.

8. A metallurgical vessel according to claim 1, substantially as described with reference to the accompanying drawing.