GB2060842A

GB2060842A - Methods of repairing refractories for sliding valves and means for performing it

Info

Publication number: GB2060842A
Application number: GB7926771A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-08-01
Filing date: 1979-08-01
Publication date: 1981-05-07

Abstract

Method of repairing refractories for sliding valves, fixed to any metallurgical container in order to pour any kind of molten metal, consisting in filling the damaged/eroded parts with suitable cement(s) and a further method of repairing said refractories for sliding valves by drilling a suitable hole and by fitting in it a suitable insert.

Description

SPECIFICATION Methods of repairing refractories for sliding valves and means for performing the method I, Ernesto Fichera, of Eriksbergsgatan 14, 114 30 Stockholm, Sweden, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to methods of repairing refractories used in the sliding valves attached mostly at the bottom of any metallurgical vessel, especially ladles, in order to pour any kind of molten metal, especially any kind of steel.

The sliding valves according to BPS 838520 of 1960 and to the Italian patent 611204 of 1959 have been used successfully. But by far more successfull has been the use of the sliding valve according to BPS 1.115.199 of 1964 even because the last makes it possible to empty more than one ladle without changing moveable plate, the fixed refractory plate, the discharge cone (1, 2 respectively 3 of Fig. 1).But even if for said refractories shapes very high qualities of refractories zircon, high alumina or magnesite have been used, the changement of said refractories has been necesary-after that some charges have been successfully poured-because of the wear due to the thermochemical-mechanical erosion of the fluid metal passing through said refractories and not seldon because of the oxigen lancing used where frozen steel or slag obstruct their bores. Because of said wear, the sliding valve is no longer tight and thus cannot be used.

The present invention seeks to overcome the changement of a/m refractories and of every further refractories where this invention can be used for instance the refr. 32 of PBS 838520 showing the moveable plate and the discharge cone of one single piece.

The a.m. lack of tightness because of the wear of the refractories of the sliding valve, is due principally to two reasons. The first reason is that the lower surface of the fixed plate 2 and/or the upper surface of the moveable plate 1 (said surfaces have to be plain-they are usually grinded-in order to secure the indispensable tightness of the sliding valve) are no longer plain but show relatively small up to relatively big grooves and/or relatively small up to relatively big ditchings, the last due often to the a.m. oxigen lancing and not only to the a.m. thermo-chemical-mechanical erosion.As generally known, the fluid metal penetrates even in the smallest interstices (often only in very small quantities) and freezes immediately: by this the moveable plate and the fixed plate remain like welded one to another and it is practically impossible for the sliding plate to glide against the fixed plate. That is: the sliding valve is out of service. The second reason is due to the enlargement of the pouring holes principally of the plates 1 and 2 because of the a.m.

erosions. When said pouring holes have so increased that in the completely closed position of the sliding plate 1, said plate oven because of the a.m. grooves and/or dichtings-is no longer tight against the fixed plate 2, then steel flows through the sliding valve, that is the sliding valve is no longer tight and the refractories 1, 2 and 3 have to be changed.

Figure 1 shows the position completely closed of the sliding valve.

Figure 2 shows the sliding valve in closed position but it is not tight because of grooves and dichtings of the plates 1 and 2.

Figure 3 shows the sliding valve no longer tight because the bores of plates 1 and 2 have increased and because of grooves and dichtings of said plates.

The present invention seeks to overcome the difficulties and drawbacks due to the lack of tightness (because of the a.m. first and second reason) and to provide methods and means for performing of the methods so that grooves and/or ditchings and/or enlargements of the pouring holes of the refractories are eliminated by repairing and not by changing the damaged, that is the no longer suitable refractories of the sliding valve.

According to the invention the damaged flat surface of the refractories in question (in this example: moveable plate 1 and fixed plate 2) can be repaired by filling the a.m. grooves and/or ditchings with a suitable refractory cement (f.i. magnesite and/or high alumina) which will fill completely said grooves and/or ditchings. Before filling grooves and/or ditchings, it is advisable to clean from steel and/or slag tha damaged flat surface of the refractories in question. After filling, the filling material must have a flat surface at the same level as the remaining undamaged surface of the repaired refractories or it may relatively slightly protrude. In no case the flat surface of the filling material may form any cavity in respect to the remaining undamaged surface of the repaired refractory, just in order to avoid the a.m. penetration of fluid metal.

According to the invention the pouring holes of the refractories in question, enlarged by the erosion of fluid steel and/or oxigen lancing, can be brought back to the initial diameters (or to any other wished diameter) by filling the enlarged hole with suitable cement, f.i. magnesite and/or high alumina cements. Usually a tube-preferably of any suitable inflammable material, f.i. plastic, carton-is put inside of the enlarged pouring hole (Fig. 4) in order to get exactly the wished diameter. The tube is usually left in the hole after the reparation.A.m. suitable cement is put between the enlarged hole and said tube (Fig. 4). The tube is easily burnt by the molten metal poured through it. The upper part of the repaired pouring hole as explained above has to be a flat surface at the same level as the undamaged part of the surface of the plate in question.Above mentioned reparations can be repeated again and again.

According to a further invention the a.m.

refractories can be advantageosly repaired as follows: Figure 5 shows a refractory plate with its original pouring hole 5 and its original plain, usually grinded surface A-B.

Figure 5A shows the refractory plate (after use) with its enlarged hole 6, its dichting 7.

Figure 5B shows the refractory plate with 3 grooves 8-9-10 and its somewhat enlarged hole 11.

According to this further invention in order to repair such damaged plate, a bore 1 2 is bored (Fig. 6usually by means of diamant drills which take away preferably all damaged parts (Fig. 5A and 5B) of the plain surface A-B of the refractory in question. In this bore 1 2 is put an insert 1 3 (Fig. 6A) whose outside diameter corresponds to the bore 1 2. Between bore 1 2 and insert 1 3 is put any suitable refractory cement 14, f.i. high alumina or magnesite cement preferably of suitable relatively thin thickness and of suitable density.

The insert 1 3 will be of suitable material (f.i.

high alumina or magnesite or zircon) depending among others on the quality of steel to be poured, on what it has to be poured a.s.o.

The insert 1 3 has an internal bore 1 5 usually of same diameter as the pouring hole 5 of the undamaged refractory in question (Fig. 5).

The insert 1 3 has to be fitted so that, its flat surface C-D will be at the same level as the remaining surface A-B, Fig. 5, of the refractory plate. To this purpose it is advisable to put the plain, usually grinded surface A-B against a suitable plain surface E-F. The more is damaged the plate, the bigger will be the diameter of the bore 1 2. The bore 12, shown in Fig. 6, has nearly the maximum diameter which can be bored in the plate in question.

The bore 1 2 may have the same center H as the bore 5 (as shown in Fig. 5 and Fig. 12) or may have a different center, preferably moved, in this case, towards the left part of the refractory, where there are grooves and/ or ditchings, in order to reduce the diameter of the insert.

In case of long insert, the insert can be of more than one piece because of several reasons, among others that it is easier to fix two shorter inserts than one long insert in a long hole. The two (or more) parts of the insert could be produced, if so wished, with the well known male/female conjunction.

Both above mentioned methods of repairing refractories of course can be applied to the upper nozzle 4 (Fig. 1).

The considerable technical and economical advantages of both above methods will be certainly highly appreciated by metallurgists and users of any sliding valve.

Claims

1. A method of repairing the plain, usually grinded surface of the refractories of sliding valves of any kind, fixed in a suitable way to any metallurgical container, for instance ladles, in order to pour any kind of molten metal, for instance steel, said plain surface being usually more or less damaged during the use of the sliding valve, characterized in that the damaged parts of said plain surface are filled in a suitable way with any suitable refractory material, in order that the repaired refractory will be suitable again for its function as a part of the sliding valve.

2. A method of repairing refractories as claimed in claim 1, characterized in that the repaired plain surface has to be at the same level as the other parts of said plain, usually grinded surface of the refractory in question.

3. A method of repairing refractories as claimed in claim 1, characterized in that the repaired plain surface protrudes relatively slightly the other parts of said plain usually grinded surface of the refractory in question.

4. A method of repairing the hole of the refractories as claimed in claim 1, said hole usually getting enlarged during the use of the sliding valve, characterized in that said enlarged hole is filled in such way with any suitable refractory materialwhich can be put between the enlarged hole and a device, usually a round tube, preferably of any suitable inflammable 'material, which is put in said enlarged hole)-to bring back said enlarged hole to any desired diameter size, said tube, being left in the repaired hole after said reparation.

5. A method of repairing the hole of refractory as claimed in claim 4, characterized in that the upper part of the refractory material used to repair the enlarged hole, is plain and at the same level of-that is has to be coplanar with-the other parts of the plain, usually grinded surface of the repaired refractory.

6. A method of repairing the hole of refractory as claimed in claim 4, characterized in that the upper part of the refractory material used to repair the enlarged hole is plain and protrudes relatively slightly the other parts of said plain surface of the refractory in question.

7. A method of repairing the plain, usually grinded surface of the refractories as claimed in claim 1 and the hole of the refractories as claimed in claim 4, characterized in that more than one filling suitable refractory material is used.

8. A method of repairing the plain, usually grinded surface of the refractories as claimed in claim 1 and the hole of the refractories as claimed in claim 4, characterized in that said suitable filling refractory materials are preferably high alumina and/or magnesit and/or zircon cements and/or mortars.

9. A further method of repairing the plain, usually grinded surface of the refractories of sliding valves of any kind, fixed in any suitable way to any metallurgical vessel, for instance ladles, in order to pour any kind of molten metal, for instance steel, said plain surface being usually more or less damaged during the use of the sliding valve, characterized in that said damaged parts of said plain surface are repaired by drilling in said refractories a hole of such diameter that the whole or part of a.m. damaged plain surface of the refractory in question is taken (drilled) away and in said hole is fitted a suitable insert of suitable refractory material in order that the repaired refractory will be suitable again for its function as a part of the sliding valve.

10. A method of repairing refractories as claimed in claim 9 characterized in that the repaired plain surface has to be at the same level of-that is has to be "coplanar" with-the other parts of the plain, usually grinded surface of the repaired refractory in question.

11. A method of repairing refractories as claimed in claim 9 characterized in that the repaired plain surface protrudes relatively slightly the other parts of the plain, usually grinded surface of the repaired refractory in question.

1 2. A method of repairing the hole of refractories, as claimed in claim 9, said hole usually getting enlarged during the use of the sliding valve, characterized in that said enlarged hole is repaired by drilling a hole of suitable diameter and in which an insert of suitable refractory material is fitted in order to bring back said enlarged hole to any desired diameter size.

1 3. A method of repairing refractories as claimed in claim 12, characterized in that between insert and said hole, drilled in the refractory to be repaired, is put a suitable refractory material.

1 4. A method of repairing refractories, as claimed in claim 1 3 characterized in that between insert and said hole drilled in the refractory in question, is put more than one suitable refractory material.

1 5. A method of repairing refractories, as claimed in claim 1 3 and/or 14, characterized in that suitable refractory materials are preferably high alumina and/or magnesit and/or zircon cements and/or mortars.

1 6. A method of repairing refractories as claimed in claim 12 characterized in that the upper part of the fitted insert and of the cement, mortars and the like used to fix the insert to the drilled refractory, is plain and at the same level as the other part of the plain, usually grinded surface, of the repaired refractory.

1 7. A method of repairing refractories as claimed in claim 1 2 characterized in that the upper part of the fitted insert and of the cement, mortars and the like used to fix the insert to the drilled refractory is plain and protrudes slightly the other parts of the plain, usually grinded surface of the repaired refractory.

1 8. A method of repairing refractories as claimed in any of the claim 9 to 1 7 characterized in that the center of the bore of the insert may not necessarily be the same center of the initial bore which has to be repaired, but may be suitably moved towards the damaged part of the refractory in question.

1 9. Application of the methods of reparation of refractories as claimed in any preceding claim, to refractories used for pouring of molten metals by means of any kind of sliding valve.

20. Combination of the mechanical parts of any sliding valve with suitable refractories of which at least one is repaired as claimed in any preceding claim.