GB2078549A

GB2078549A - Repairing the Refractories of Metallurgical Vessels

Info

Publication number: GB2078549A
Application number: GB8116667A
Authority: GB
Original assignee: Centre de Recherches Metallurgiques CRM ASBL
Current assignee: Centre de Recherches Metallurgiques CRM ASBL
Priority date: 1980-05-30
Filing date: 1981-06-01
Publication date: 1982-01-13
Also published as: DE3120861A1; FR2483589A1; GB2078549B; LU83399A1; FR2483589B1; BE883591A

Abstract

The refractory lining of the nose of a steel converter is repaired by spraying refractory material at a worn region of the lining by means of a burner having three coaxial tubes 1- 3. A coolant flows in a conduit defined between the two outer tubes 1,2 and closed at the burner outlet end. Oxidising gas (e.g. O2) is passed through the innermost tube 3. A combustible fluid (e.g. fuel gas) carrying particulate refractory material (e.g. 3 to 6 kg/Nm<3>) passes through the space between the two inner tubes 2,3 (e.g at a speed of 5 to 40 m/s). <IMAGE>

Description

SPECIFICATION Repairing the Refractories of Metallurgical Vessels The present invention relates to methods of repairing the refractories of metallurgical vessels.

It is particularly applicable to tapholes and to the noses (mouths) of steel converters.

The long-practised repair of metallurgical vessels when the refractory lining of these vessels has become too thin or has deteriorated either totally or locally, consists in replacing all or part of the affected zones by new refractory, which may be in a shaped form (for example bricks of a suitable shape) or a non-shaped form (for example a granulate combined with one or more binding agents and suspended in a fluid). The zones recharged in this way are then subjected to suitable firing if nonfired materials are used.

In order to improve the strength of the repaired materials and to enable the operation to be carried out when there is a high temperature within the vessel, it has been proposed to use a carrier gas enabling the refractory materials used for the purposes of repair to be sprayed against the wall of the vessel to be repaired. These materials, possibly with a binding agent, are then subjected to suitable heating at the spray area, for example using a blowlp or a burner, in order to complete the consolidation of the zone to be repaired, under good conditions.

The present invention utilizes a burner which comprises three coaxial tubes, the conduit between the two outer tubes being closed at the output end of the burner, and which further comprises: means for causing a cooling fluid, for example water, to flow between the two outer tubes, means for causing a highly oxidising gas, for example pure oxygen, to pass through the burner within the innermost tube, means for causing a combustible fluid, preferably gaseous, containing in suspension refractory materials of suitable granular size, to pass through the burner in the space between the two inner tubes.

In the accompanying drawing, the sole Figure is a longitudinal section through a preferred embodiment of a burner.

The burner illustrated has three coaxial tubes 1,2,3. For cooling the burner, a suitable coolant (e.g. water) is supplied to the space between the outer tubes 1,2 by auxiliary pipes 4 (only one of which is shown). The outlet end 5 of each pipe 4 is adjacent the outlet end of the burner, where the annular conduit defined between the tubes 1,2 is closed off. The coolant discharges from the rear end (not shown) of this conduit.

The space between the inner tubes 2,3 is used for the passage of a stream of fuel gas carrying granular refractory material. This space is maintained constant by means of suitably located spacers 6. The innermost tube 3 is used for the passage of oxygen or another oxidising gas.

The sections 7 which are subject to greater abrasion are reinforced in thickness and with an abrasion-resistant material, for example manganese steel, hard or surface-hardened cast iron, alloys containing suitable elements such as Cr, Mo, W, Ni, V, Mn, tungsten carbide, cermets, or sintered material. At the outlet end of the burner, the coolant conduit is closed off by a copper member 8, and replaceable annular copper inserts 9 and 10 are also provided. Thus the end sections of the tubes are advantageously provided with or constituted by sleeves or inserts of a material providing high dissipation of heat, and these sleeves or inserts may be replaced.

The end of the innermost tube may be provided with a jet deflector (not shown), for example fixed and shaped as a helix.

Using a burner as described above, the nose of a steel converter can be repaired under excellent conditions.

It should however be noted that although the present description and the claims are based on the use of such burners for repairing the noses of converter, these burners may, within the scope of the present invention, be used for repairing any refractory wall of a metallurgical vessel.

During their working life or campaign, converters suffer progressive deterioration of their refractory lining and in particular of the refractory lining of the nose. The latter becomes worn in a differential manner, both at its inner end and in its passage itself. At the inner end th .;ear may be seen as a marked recess in the inlet opening (which is the cause of a considerable slag discharge which is harmful to the quality of the metal). In the passage the wear may be seen as a cross-sectional increase as well as deterioration of the rectilinear profpe of the passage wall. In addition, it has been noted that, during successive conventional repairs in which refractory material is deposited in an asymmetrical manner, the position of the passage tends to become upwardly displaced towards the top of the converter, eventually reaching its external metal shell.Furthermore, it is difficult to reline this part of the refractory of the converter in the correct position and with the correct profile.

The method of the invention enables these drawbacks to be remedied in a rapid, accurate, and efficient manner.

Preferably, use is made of one or two burners of the type described above, wherein the burner may, in accordance with requirements, be bent substantially, e.g. through 900, or be slightly bent (less than 500, for example 1 5 to 300), at its outlet end.

The or each burner may be disposed on a support device enabling the positioning and orientation of the burner with accuracy with respect to the converter nose to be repaired, the converter itself being suitably tilted, preferably with the nose in a horizontal position. At least one of the burners is then introduced into the nose, the more bent burner (when two burners are used) being introduced first into a suitable position in order to carry out repair of the recessed portion (worn area) of the iniet opening (inner end of the nose), this first burner then being withdrawn from the taphole, and the less bent burner then being used, e.g. introduced into the nose up to a suitable position, for example the extremity of the nose, in order to carry out progressive relining from the first repair, for example from the interior of the exterior of the converter.

If the two burners are both capable of rotating about their longitudinal axis, even during operation, it is possible to obtain a differential radial repair which takes into account the local differences in wear noted in the refractory lining.

Repair is carried out by spraying particulate refractory material by means of the burner, which may be subjected to a movement of rotation (possibly oscillating) about its axis, or to a movement of translation (possibly reciprocating) along its axis, or to both these movements combined in a suitable manner.

In the case in which only a single burner is used, it has been found advantageous to select a burner whose end part adjacent the outlet is slightly inclined to its axis (for example 1 5 to 300), to dispose the converter such that its nose is inclined towards the interior of the converter, and then to carry out the repair of the nose from its exterior (external side of the converter). This is particularly advantageous in the case in which the wear in the passage of the nose is very marked.

According to a first technique, the burner is caused to penetrate into the converter nose from the exterior to the interior, whilst being rotated about its axis. It has been noted that this method more readily enables refractory material to be sprayed onto a surface which is still hot and has not had time to cool down.

According to a second technique, the single burner is maintained in practice outside the converter, facing and in the vicinity of the orifice of its substantially horizontal or inwardly inclined nose and the refractory material is sprayed onto the surface to be repaired, the fuel gas and/or the oxidising gas being under a pressure such that the hot refractory mass which is sprayed reaches the internal surface of the taphole over its entire length in a progressive manner from the outside towards the inside of the converter under the action of the pressure, the burner preferably remaining in rotation about its own axis. By way of example it would be possibie to use a fuel gas speed of 5 to 40 m/s and a refractory content of 3 to 6 kg/Nm3.

This technique has obvious operational advantages and enables converter nose repair which is in practice as efficient as that obtained by means of the other variants.

According to an advantageous variant of this second technique, the pressure of the oxidising gas and/or of the fuel gas is modified during the repairing operation such that the sprayed refractory mass accurately reaches the various portions of the passage to be repaired, or such that the repair is carried out with a predetermined progression.

Claims

1. A method of repairing the refractory iining of the nose of a steel converter or the refractery lining of a wall of a metallurgical vessel, comprising spraying refractory material at a worn region of the lining by means of at least one burner comprising three coaxial tubes, the conduit defined between the two outer tubes being closed at the outlet end of the burner, the burner further comprising: means for causing a coolant flow in the said conduit, means for passing oxygen or another oxidising gas through the innermost tube, and means for passing a combustible fluid carrying particulate refractory material through the space between the two inner tubes.

2. A method as claimed in claim 1, in which two said burners are used in succession, each burner having its outlet end portion inclined to its longitudinal axis, the outlet end portion of the first burner being inclined at a greater angle than that of the second burner, the first burner is introduced in the converter nose until the outlet end of the burner is practically opposite a region of the inlet opening of the nose which has been recessed by wear at the inner end of the nose, repair of the said region is then carried out by means of the first burner, the first burner is withdrawn, and then a further worn region of the lining of the nose is repaired by means of the second burner.

3. A method as claimed in claim 2, in which the repair by means of the second burner starts from the region which has already been repaired by means of the first burner.

4. A method as claimed in claim 2 or 3, in which at least one of the burners is rotated about its longitudinal axis during repair.

5. A method as claimed in claim 1, in which use is made of only a single said burner, the converter being so disposed that its nose is upwardly inclined towards the body of the converter, and the repair of the nose is carried out from the exterior of the nose.

6. A method as claimed in claim 4 or 5, in which the outlet end portion of the burner is inclined to its longitudinal axis by an angle of less than 500

7. A method as claimed in claim 6, in which the inclination angle is 10 to 300.

8. A method as claimed in claim 6 or 7, tn which the burner is rotated about its longitudinal axis during repair.

9. A method as claimed in any of claims 5 to 8, in which the burner is caused to penetrate into the nose from the outside towards the inside during repair.

10. A method as claimed in any of claims 1 to 8, in which the burner or the second burner is maintained substantially outside the converter, opposite and in the vicinity of the nose, which is substantially horizontal or upwardly inclined towards the body of the converter, the pressure of the combustible fluid and/or the pressure of the oxidising gas during repir being such that the refractory material which is sprayed progressively reaches the interior of the nose over its entire length from the exterior towards the interior of the converter under the action of the said pressure(s).

11. A method as claimed in any preceding claim, in which the combustible fluid is gaseous and is discharged from the burner at a speed of 5 to 40 m/s.

12. A method as claimed in any preceding claim, in which the combustible fluid is gaseous and carries 3 to 6 kg of refractory material per Nm3.

1 3. A method as claimed in any preceding claim, including varying the pressure of the oxidising gas and/or the pressure of the combustible fluid during repair, in order to vary the location at which the sprayed refractory material strikes the lining.

14. A method as claimed in any preceding claim, in which the burner is substantially as described with reference to, and as shown in, the accompanying drawing.