Plastic and nonmetallic article shaping or treating: processes – Furnace lining formation or repair
Patent
1992-08-04
1994-07-19
Aftergut, Karen
Plastic and nonmetallic article shaping or treating: processes
Furnace lining formation or repair
156 98, 264 32, 264 35, 264 36, 264 80, 264139, 264162, 264265, 264269, 266 44, 266271, 266281, 425 12, 427140, B32B 3500, C21B 706, F27D 116
Patent
active
053306902
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
1. Field of the Invention
The invention relates to a process for renewing a refractory lining in a ladle and an apparatus for accomplishing the process.
2. Description of the Related Art
To an increasing extent nowadays, metallurgical vessels are no longer being lined (faced) with refractory bricks. Instead, a casting technique is used in which a refractory casting material, generally a thixotropically acting casting material, is introduced into the interspace between a template or mold which determines the desired clear interior space of the ladle or other type of metallurgical vessel and the vessel wall to be lined. Due to its thixotropic behavior, the material flows very well under the action of vibrations (generally of the template or mold), even in the case of low water contents, and fills every cavity.
German Offenlegungsschrift 3,741,073 has already disclosed a process in which, at the end of the life of a metallurgical vessel, that is to say after the inner layers of the casting material which have been exposed to the molten metal have worn away, instead of breaking out completely the remainder of the refractory lining, which is of course still serviceable, only the remaining slag residues and the slag-penetrated surface layers of the old lining are superficially removed. This does not involve the production of a geometrically regular surface but an operation in which a so-called slag-stripping robot with tools mounted on movable arms, rolling on the surface and having projecting sintered-carbide studs acts on the surface under the action of vibrations and removes or at least roughens it to the desired extent. During this operation, however, the tools follow the largely existing contour of the old lining. The template is reintroduced into the metallurgical vessel having the old lining cleaned in this way, and the interspace between the template and the old lining is then filled again with thixotropic casting material under the action of vibrations. In this way, it is possible to save up to 50% of the expensive lining material. The preceding machining of the surface of the old lining results in a good bond with the newly applied refractory material.
The known process, however, proves to be too expensive in certain cases. This is the case when the skull, i.e. the slag layer, is so thick that the time involved in removing it and the associated wear of the tools are too great to keep the process cost-effective. In addition, the remaining portion of the refractory lining is subjected to high mechanical stresses by the prolonged action of the tools and cracks can thus arise.
SUMMARY OF THE INVENTION
The object on which the invention is based is to allow the refractory lining of metallurgical vessels to be renewed in an economical manner even in such cases.
This object is achieved by a process for renewing a refractory lining, having a predetermined thickness, of a ladle, the ladle containing at least one of a slag which is adhered to the refractory lining and a slag-impregnated surface layer of the refractory lining. The process includes the steps of: heating the ladle; tilting the ladle on a side thereof such that the ladle is sloped relative to a horizontal plane so that an opening of the ladle is located proximate a lower end of the sloped ladle; melting at least one of the slag and the slag-impregnated surface layer via a high-temperature burner that utilizes pure oxygen and allowing the melted at least one of the slag and the slag-impregnated surface layer to run out of the opening so that after melting has ended, the refractory lining has an exposed glassy surface; cooling the ladle; roughening the exposed glassy surface; and then casting a second refractory lining to adhere to the roughened exposed glass surface of the first refractory lining such that the thickness of the combined first and second refractory linings is approximately the same as the predetermined thickness. The object is also met by an apparatus for renewing a refractory lining of a ladle used for casting metallurgi
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Aftergut Karen
Intocast GmbH Feuerfestprodukte und Giesshilfsmittel
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