EP0429323B2 - Metal treatment ladle with a refractory base coating and process for making such refractory base coating - Google Patents

Abstract

The subject of the invention is a ladle for treating metal, comprising a metal casing (1) which is equipped, on its inner surface, with a refractory wall coating (3) and with a refractory base coating (4) carrying a taphole (5), characterised in that the surface of the refractory base coating (4) in contact with the metal under treatment is a concave surface having, at any point, a slope directed towards the taphole (5). A further subject of the invention is a process for producing such a refractory base coating.

Description

The present invention relates to a pocket for the production of a metal comprising a metal envelope provided, on its internal surface, a refractory wall lining and a lining bottom refractory with a tap hole.

The present invention also has for subject a process for producing such a coating background refractory.

In the field of metallurgy, a such a pocket is known and, in steelworks, one seeks to produce pocket bottom coatings having a slope towards the tap hole to improve metal flow at the end of casting and reduce thus the metal losses.

A continuous flow distributor with a coating whose bottom is in the form of a gutter of semi-cylindrical section, is known from document US-A-3,333,746.

We also know in document GB-A-1 348 541 a bottom refractory lining of a metal container, in particular a degassing container of molten steel. The container has an envelope metallic and a refractory bottom coating having a tap hole eccentric to the center of said bottom surface. The tap hole is bordered with curb bricks to which are connected brick belts. The metallic envelope has a bottom inclined towards the tap hole and the upper surface of the refractory lining in contact with liquid metal is parallel to the bottom of the envelope.

But, a flat, pocket bottom coating, tilted, has the main disadvantage of lifting by the effect of thermal expansion of materials refractory, during heating of the pocket. This phenomenon is even more important when using basic materials whose coefficient of expansion is higher than that of acidic materials.

The dilations generate, by a detachment in the center, between the covering and the bottom of the pocket, a buckling of said bottom coating.

This type of deformation can cause rapid deterioration and falling coating background refractory when emptying the slag.

The object of the present invention is to avoid, among others, the peeling of the coating bottom refractory of a pocket for the elaboration of metal, for example steel.

The object of the present invention is thus a pocket for the production of metal comprising a metal envelope provided, on its internal surface, a refractory wall lining and a lining bottom refractory with a tap hole, offset from the center of the surface of said refractory lining, characterized in that the metal shell has a flat bottom and horizontal and the refractory lining surface of bottom in contact with the metal being processed, is formed by a concave surface having a shape general spherical and at any point a directed slope towards the tap hole.

Preferably, the refractory lining bottom consists of at least one assembly of elements independent separated by seals, said independent elements obtained by molding being produced and arranged in such a way as to create a vault when the pocket is overturned.

According to a particular embodiment of the invention, the refractory lining is consisting of at least one layer of security and at least minus a wear layer, the safety layer being constituted by an assembly of independent elements.

• les éléments indépendants de fond de poche comportent des faces latérales munies d'au moins une gorge s'étendant sensiblement parallèlement à la surface du fond de poche,
• les éléments indépendants de fond de poche sont scellés avec un béton à variation permanente de dimension positive rémanente,
• l'ensemble des éléments indépendants de fond de poche forment une mosaïque dont les joints sont les uns concentriques au trou de coulée et les autres rayonnants par rapport audit trou, les joints rayonnants étant décalés d'un joint concentrique à un autre.
• la couche de sécurité est entourée d'une ceinture annulaire susceptible de constituer une surface de démarrage du maçonnage du revêtement réfractaire de la paroi de l'enveloppe métallique,
• la ceinture annulaire de section sensiblement quadrilatère comporte au moins un épaulement extérieur définissant au moins une surface d'appui hélicoïdale, la largeur de ladite surface d'appui correspondant à l'épaisseur d'au moins une couche de revêtement réfractaire de paroi.

According to other characteristics of the invention:

• the independent pocket bottom elements comprise lateral faces provided with at least one groove extending substantially parallel to the surface of the pocket bottom,
• the independent elements of the bottom of the pocket are sealed with a permanently variable concrete of positive residual dimension,
• all of the independent elements at the bottom of the pocket form a mosaic the joints of which are some concentric with the taphole and the others radiating with respect to said hole, the radiating joints being offset from one concentric joint to another.
• the safety layer is surrounded by an annular belt capable of constituting a starting surface for the masonry of the refractory lining of the wall of the metal envelope,
• the annular belt of substantially quadrilateral section has at least one external shoulder defining at least one helical bearing surface, the width of said bearing surface corresponding to the thickness of at least one layer of refractory wall covering.

• on fabrique un moule formé par un fond convexe sphérique, et comportant des parois verticales constituant des compartiments correspondant à la géométrie des éléments du revêtement réfractaire de fond, lesdites parois ayant une section correspondante à celle des joints,
• on coule dans chaque compartiment ainsi formé un béton réfractaire choisi,
• et on démoule après la prise du béton en référençant chacun desdits éléments du revêtement réfractaire de fond qui comporte une face plane destinée à venir en appui sur le fond de poche.

The subject of the invention is also a method for producing a bottom refractory lining in which:

• a mold is formed formed by a convex spherical bottom, and comprising vertical walls constituting compartments corresponding to the geometry of the elements of the refractory lining of the bottom, said walls having a section corresponding to that of the joints,
• a selected refractory concrete is poured into each compartment thus formed,
• and it is removed from the mold after setting of the concrete by referencing each of said elements of the bottom refractory lining which has a flat face intended to come to bear on the pocket bottom.

• la Fig. 1 est une vue partielle en coupe d'un premier mode de réalisation d'une poche pour l'élaboration de métal selon l'invention,
• la Fig. 2 est une vue partelle en coupe d'un second mode de réalisation d'une poche selon l'invention,
• la Fig. 3 est une vue partielle en coupe d'un troisième mode de réalisation d'une poche selon l'invention,
• la Fig. 4 est une vue de dessus d'un ensemble formé par une rampe annulaire de démarrage de maçonnage des briques de paroi et par un revêtement de fond de poche selon l'invention,
• la Fig. 5 est une vue en coupe d'un moule dans lequel sont coulés les éléments indépendants de la mosaïque formant un revêtement réfractaire de fond de poche selon l'invention.

Other characteristics and advantages of the present invention will appear during the description which follows, given with reference to the accompanying drawings.

• Fig. 1 is a partial sectional view of a first embodiment of a pocket for producing metal according to the invention,
• Fig. 2 is a partial sectional view of a second embodiment of a pocket according to the invention,
• Fig. 3 is a partial sectional view of a third embodiment of a pocket according to the invention,
• Fig. 4 is a top view of an assembly formed by an annular ramp for starting the masonry of the wall bricks and by a pocket bottom coating according to the invention,
• Fig. 5 is a sectional view of a mold in which are poured the independent elements of the mosaic forming a refractory lining of the pocket bottom according to the invention.

In Fig. 1 the lower part is shown a pocket for making metal, for example of steel, comprising a metal casing 1, by cylindrical example, provided on its internal wall 2 with a refractory lining of wall 3 and a lining bottom refractory 4 provided with a taphole 5.

The bottom refractory lining 4 is composed a refractory layer whose surface 6 in contact with the metal to be worked out is a concave surface presenting at any point a slope directed towards the hole of casting 5.

The concave shape 6 of the refractory lining of bottom 4 creates an arch effect when the pocket is overturned and therefore the arch effect prevents detachment said bottom refractory lining 4.

According to a second embodiment shown in Fig. 2, the bottom refractory lining 4 is consisting of an assembly of several independent elements 4a separated by joints 7 of refractory concrete.

The independent elements 4a constituting the coating background refractory 4 are made, by example by molding, and each have a specific shape for readjustment to each other others in the bottom of the metal casing 1 of the poached. Their arrangement and shape are determined so as to obtain a vault effect when the pocket is overturned.

The seals 7 are preferably placed, of a on the one hand, concentrically with tap hole 5 and, on the other part, radiating from this same tap hole, said radiating joints being further offset by one concentric joint to each other. The side faces of independent elements 4a are provided with grooves 8 forming on the seals 7, projections which block the sliding of said elements 4a relative to each other to others.

The grooves 8 extend substantially parallel on the surface of the pocket bottom.

The independent elements are jointed with permanently variable refractory concrete positive residual, other physical properties sealing concrete are close to those refractory material used for the realization of independent elements 4a.

The sealing concrete which forms the joints 7 is arranged to balance or compensate for deformations of expansion due to the geometry of the assembly independent elements 4a.

According to a third embodiment shown in Fig. 3, the refractory lining of the wall has at least one security layer 10 and at least minus a wear layer 11, and the refractory lining background has at least one security layer 12 and at least one wear layer 13.

The wear layers (11, 13) are made of refractory bricks the quality of which is determined by the conditions of use and the stresses undergone in the different parts of the pocket refractory lining. These bricks can be made from aggregates, especially aluminous, dolomite, magnesia.

The bricks constituting the security layer 10 and the wear layer 11, for example of semi format universal, are supported on an external shoulder 14 of an annular ramp 15 of masonry start bricks of the refractory lining of the wall. The outer shoulder 14 defines two surfaces helical supports 16 and 17 respectively.

The bearing surface 16 has the width of the layer 10 security wall and the bearing surface 17 has the width of the wear layer 11 of the wall.

Furthermore, the outer shoulder 14 is a means of peripheral blocking of the security layer 12 pocket bottom.

For this purpose, on the bottom of the pocket is deposited, in the space delimited by the annular ramp 15, the pocket bottom security layer 12, shaped lenticular and having a sealed planar face 12a on the inner face of the bottom of the metal casing 1 and a face 12b having a concave surface sufficiently spherical having at all points a slope towards the tap hole 5.

On the concave face 12b is masonry the layer wear base 13 in refractory bricks which marries the shape of the concavity.

The surface 13b of the bottom wear layer 13, in contact with the metal being worked on, defines a sphere whose center is located on the longitudinal axis tap hole 5.

The bottom wear layer 13, resting on the surface concave 12b substantially spherical of the layer security 12 bottom, a, by a vault effect, tendency to press against said layer of security 12 during thermal expansion, which ensures its mechanical resistance when the pocket is overturned.

The annular ramp 15 and the safety layer 12 both consist of the same material which is generally an aluminous concrete based Andalusite. This refractory concrete must have good cold mechanical resistance and pyroscopic resistance acceptable.

Fig.4 is a top view of the assembly formed of the annular ramp 15 and the safety layer 12 background.

The annular ramp 15, on which is molded the outer shoulder 14 forming the two ramps helical starting 16 and 17 respectively bricklaying of refractory lining of wall is cast on site. The security layer 12 background consists of a set of elements 20 forming a mosaic and grouted with concrete coefficient of thermal expansion slightly higher than the coefficient of thermal expansion refractory material constituting said elements independent 20. The other physical properties of sealing concrete constituting the joints 21 between the independent elements 20 are close to those of refractory material used for making said independent elements 20.

The seals 21 are arranged so as to balance or to compensate for the expansion deformations due to the geometry of the set of independent elements 20. The seals 21 are preferably placed, on the one hand concentrically with the tap hole 5 and on the other hand radiating with respect to this same hole of casting 5, the radiating joints being more placed in staggered relative to each other.

The lateral faces of the independent elements 20 are also provided with a groove 22 which forms, on the seals 21 cast, projections which block the sliding of the independent elements 20 of the layer security 12 relative to each other.

Referring now to FIG. 5 we will describe the method of making, in prefabricated, independent elements (4a, 20) of the coating mosaic base 4 or security layer 12 of background.

For this purpose, a mold 30 formed in a template is used. of the refractory lining 4 or the layer 12 bottom security. The mold 30 is made up of a cylinder 31 placed on a convex surface 32 producing the curve of the surface of the refractory lining 4 bottom or 12 bottom security layer of pocket. The mold 30 is partitioned with walls vertical 33 whose cross section corresponds to the shape seals (7, 21), said vertical walls 33 being placed so as to determine compartments forming molds for the elements (4a, 20) respectively of the refractory lining (4) at the bottom or security layer 12.

After pouring the refractory material 34 into the different molds making up the mosaic, then mold release, the elements (4a, 20) of specific shape are referenced. They together constitute either a refractory lining 4 at the bottom, i.e. a layer of security 12 of background of homogeneous physical characteristic.

Although in the examples described the form concave of the surface in contact with the metal to be worked either of substantially spherical shape, others shapes would suit like for example a shape cylindrical or ogival, these shapes allow a arching of the refractory lining and its mechanical strength.

In addition, such a configuration ensures good flow of steel to the tap hole, point bottom of the surface of the refractory lining of the bottom of the pocket being formed by said tap hole.

Claims (11)

1. Ladle for the preparation of metal comprising a metal case (1) provided, on the inner surface thereof, with a refractory wall lining (3, 10, 11) and a refractory bottom lining (4, 12, 13) having a taphole (5), offcentred with respect to the centre of the surface of said refractory bottom lining (4, 12, 13), characterized in that the metal case (1) has a flat, horizontal bottom and the refractory bottom lining (4, 12, 13) surface in contact with the metal being prepared is formed by a concave surface having a generally spherical shape and at all points a gradient directed towards the taphole.
2. Ladle according to claim 1, characterized in that the refractory ladle bottom lining is formed by at least an assembly of independent elements (4a) separated by joints (7).
3. Ladle according to claim 1, characterized in that the refractory bottom lining comprises at least one safety layer (12) and at least one wear layer (13), said safety layer (12) being formed by an assembly of independent elements (20) separated by joints (21).
4. Ladle according to any one of the preceding claims, characterized in that, in the assembly of independent elements (4a, 20) constituting the refractory bottom lining (4, 12), said independent elements (4a, 20) are constructed and disposed in such a manner as to produce a vault effect when the ladle is turned over.
5. Ladle according to any one of the preceding claims, characterized in that the independent elements (4a, 20) are obtained by moulding.
6. Ladle according to any one of the preceding claims, characterized in that the independent elements (4a, 20) comprise lateral surfaces provided with at least one groove (8, 22) extending in a direction substantially parallel to the surface of the ladle bottom.
7. Ladle according to any one of the preceding claims, characterized in that the independent elements (4a, 20) are scaled with concrete having a permanent positive remanent dimension variation.
8. Ladle according to any one of the preceding claims, characterized in that the assembly of the independent elements (4a, 20) constitutes a mosaic some of whose joints (7, 21) are concentric with the taphole (5) whereas the other joints radiate relative to the taphole (5), the radiating joints being offset from one concentric joint to the other.
9. Ladle according to claim 3, characterized in that the safety layer (12) is surrounded by an annular girdle (15) capable of forming a surface (16, 17) for commencing the masonry of the refractory lining (10, 11) of the wall of the metal case (1).
10. Ladle according to claim 9, characterized in that the annular girdle (15) having a substantially quadrilateral section includes at least one outer shoulder (14) defining at least one helical support surface (16, 17), said support surface (16, 17) having a width corresponding to the thickness of at least one layer of refractory wall lining (10, 11).
11. Method for producing a refractory ladle bottom lining according to any one of the preceding claims, characterized in that it comprises:

    producing a mould (30) constituted by a convex, spherical bottom (32), and including vertical walls (33) constituting compartments corresponding to the geometry of the elements of the refractory bottom lining (4, 12), said walls (33) having a section corresponding to the section of the joints (7, 20);

    pouring into each compartment thus formed a selected refractory concrete (34), and

    stripping the elements (4a, 20) after the setting of the concrete and providing a reference on each of said elements of the refractory bottom lining, having a planar face on the ladle bottom.

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