TAP HOLE PLUGS FOR METALLURGICAL VESSELS

Abstract: A plug for the tap hole (H) of a metallurgical vessel (V) is formed by inserting in the hole (H), a container (10) having a fixed end wall (12) and a movable end wall (14), the container (10) housing a bag (27) containing a refractory mortar (26), an aperture (34) being present between the fixed wall (12) and the serrated edge (32) of a housing wall (30). The container (10) is diametrically smaller than the hole (H) so that an annular clearance is present. When the movable wall (14) is urged towards the fixed wall (12), the bag (27) is ruptured and the mortar (26) egresses into the annular clearance to form the plug. The container (10) is inserted at the end of a plunger (50) arranged to hold the container (10) and actuable to move the movable wall (14).

Description: The present invention relates to a plug for the tap hole of a metallurgical vessel. A tap hole is usually present in the side wall of a metallurgical vessel and through which molten metal from the vessel may be poured when the vessel is pivoted about a horizontal axis. Tap holes are filled with a sealing plug designed to melt when in contact with the molten metal in order that the molten metal may be poured through the tap hole. Any slag associated with the metal remains in the vessel. Generally tap holes are subject to greater wear in use than the interior of the vessel lining. As a result, the interior end of the tap hole tends to become conical in shape and the circularity of the tap hole often becomes irregular and distorted. In certain circumstances tap holes have evolved into D-shaped openings with molten metal and slag depositing along the lower surfaces of the tap holes. That is to say, slag whiskers or occasional slag carry-over and molten metal stoppings often reduce the circular opening to a D shape. These irregularities make the hole difficult to plug. It is one object of the present invention to provide a plug which can be used to seal a tap hole, even if the wall of the tap hole is worn and irregular in shape. GB-A-1515629 discloses the use of a tap hole plug in the form of a frustoconical metal body containing a mass of unhardened refractory material, the plug being releasably connected to the end of a rod and then urged into the tap hole. The present invention is based on the realisation that if the metal body is dimensioned to be received in the tap hole with a clearance in between and the refractory material is then urged out of the metal body into the hole, certain benefits result. According to the invention in one aspect there is provided a method of forming a plug in a tap hole of a metallurgical vessel, the method comprising placing a refractory mortar in a container therefor, the container being so dimensioned that when it is received in the hole there is an annular clearance in between the container and the sidewalls defining the hole, and urging the mortar out of the container through an aperture therein towards and into sealing engagement with the side walls of the hole and allowing or causing the mortar to harden. Preferably the aperture extends radially of the container and is located towards the leading end of the container. Preferably the container has a fixed leading end wall and a movable trailing end wall, and the aperture is present adjacent the fixed leading end wall. Preferably the mortar is located in a housing extending between the end walls and leaving a radial gap defining a circumferential radial aperture. Most preferably, the mortar is housed in a bag and the free edge of the housing may be serrated so that the serrated edge breaks open the bag when the movable end wall is urged towards the fixed end wall. The serrated edge is useful in the event that the temperature of the tap hole bore is too low to melt the bag. The refractory mortar may be of any known type but more especially is one comprising a refractory filler e.g zircon sand, silica sand, magnesite, alumina, bonded by a binder such as colloidal silica sol. Preferably a rod extends from the fixed end wall through the container and beyond the movable end wall, and a plunger having one part to engage the fixed end wall and another part to abut the movable end wall is connectable to the container and the plunger is connected to the rod by the one part, and the assembly so formed is advanced towards the vessel, the container is inserted into the hole following which the other part of the plunger is actuated to urge the movable end wall towards the fixed end wall to urge the mortar out of the container and into the annular clearance between the container and the side wall of the hole. Preferably the projecting end of the rod has a screw thread which is releasably engaged by a threaded socket formed in one part at the leading end of the plunger. In one preferred embodiment the plunger comprises three concentric sleeves, the outer and inner sleeves being secured together and the intermediate sleeve being arranged for axial movement relative to the other sleeves, the inner sleeve having the part to engage the fixed end wall of the container and the intermediate sleeve having another part to bear on the movable end wall of the container when the intermediate sleeve is moved to urge the mortar out of the container. Preferably the plunger includes a stop located at a distance from the forward end of the plunger so that when the stop is abutted against the outer face of the wall of the vessel, the container extends into the hole towards, but short of, the inner face of the wall. The invention includes as a separate item, a container containing a mass of a refractory mortar in a metal container, wherein a radial aperture is present in a wall of the container through which mortar may pass. The invention also includes a container having a plunger formed of three concentric sleeves; the outer sleeve and the inner sleeve being secured together, a forward end of the outer sleeve being arranged to engage the fixed end wall, the intermediate sleeve being axially movable relative to the other sleeves and having at a forward end means to engage the movable end wall of the container, and an external stop being located at a distance from the forward end of the plunger. In order that the invention may be well understood it will now be described with reference to the accompanying drawings in which Figure 1 is a side elevation of a tap hole plug with parts removed for clarity; Figure 2 is an end elevation of the plug of Figure 1 and looking from left to right in Figure 1; Figure 3 is a cross-section of the plug on line 3-3 in Figure 1; Figure 4 is a perspective view of a plunger for use in inserting the plug of Figure 1 into a tap hole; Figure 5 is an enlarged cross-section taken on line 5-5 on Figure 4; Figure 6 is a longitudinal section taken on line 6-6 in Figure 4; and Figures 7 and 8 are cross-sectional views illustrating the insertion of the plug by the plunger into the tap hole and release of the mortar. Referring now to Figure 1, a tap hole plug is a generally cylindrical container 10 which includes a pair of end wall plates or discs 12 and 14. The forward wall 12 has a pair of crossed reinforcing rods 16 disposed on its forward face. As illustrated in Figure 2, clamps 18 are welded to the outside face of wall 12 to secure the ends of the rods along the outside face of wall 12. A central rod 20 extends rearwardly from the wall 12 through a central opening in the wall 14 so that the wall 14 is mounted for longitudinal sliding movement along rod 20 which terminates in an externally threaded end 22 which projects beyond the end of a nut 24, which retains disc 14 on the rod. The container 10 contains a refractory mortar 26 which is in the shape of an annulus, with the rod 20 extending through the annulus 26. The mortar is located in a plastics bag or covering 27. The refractory mortar may be of any type and preferably comprises a zircon or silica sand, bonded into a mortar by a colloidal silica binder. The container 10 is located in a generally circular housing or wall 30 dimensioned so that wall 14 can slide therein. The wall 30 is spaced rearwardly from the forward wall 12 and has a serrated edge. The edge 32 of wall 30 defines with wall 12 a peripheral, generally radially extending aperture 34. A generally V-shaped metal guide 38 projects from the forward end of the container 10. The guide 38 comprises a pair of metal strips terminating at an apex 40 at the free end and leg portions 42 which are secured to opposite side portions of wall 30. Referring now to Figure 4, there is illustrated a plunger 50 for inserting the plug 10 into the tap hole. The plunger 50 comprises outer, inner and intermediate sleeves 52, 54 and 56 respectively. Sleeves 54 and 56 are longer than outer sleeve 52 and may for example be about 210 cm (7 feet) long. Longitudinal diametrically opposed slots 58 are present in the sleeve 56 ends. Outer sleeve 52 and inner sleeve 54 are secured together against relative axial movement by a pin 60 which extends through the slot 58. The intermediate sleeve 56 may move axially relative to the outer and inner sleeves 52 and 54. As best shown in Figure 4, a collar 61 is present adjacent the rear end of the outer sleeve 52 and a corresponding collar 62 is provided on intermediate sleeve 56 rearwardly of outer sleeve 52. A helical coil spring 64 extends between collars 61 and 62 biasing the intermediate sleeve 56 for movement in a direction, for example, left to right as illustrated in Figure 4, relative to outer sleeve 52. At rest, the pin 60 engages in the forward end of slot 58. An enlarged diameter portion 66 is formed on intermediate sleeve 56 such that, upon displacement of intermediate sleeve 56 relative to outer sleeve 52, for example, from right to left against the bias of spring 64, the enlarged portion 66 will abut collar 61 to limit axial movement of intermediate sleeve 56 in the opposite direction. In this manner, pin 60 is not subjected to shear stress when intermediate sleeve 56 reaches the extreme end of its axial displacement relative to outer sleeve 52. As best shown in Figures 4 and 5, outer sleeve 52 is provided with a stop in the form of a laterally projecting bar 70 which is much longer than the diameter of the tap hole H. The forward end of intermediate sleeve 56 defines a pusher head 72 which comprises a circular disc 73 smaller in diameter than the diameter of the tap hole and to be received within the housing 30 against the rear end wall 14 of plug 10. The forward end of inner sleeve 54 defines in an internally threaded opening 74. In the retracted position of the plunger, as illustrated, the internally threaded end 74 of inner sleeve 54 and pusher head 72 mounted on intermediate sleeve 56 lie substantially level, one with the other. The pusher head 72 flares at 76 at its juncture with intermediate sleeve 56 to accommodate the nut 24 on plug 10. In use, the container 10 is first secured to the plunger by threading end 22 of the rod 20 into the threaded end 74 of inner sleeve 54, until pusher head 72 bears on wall 14. An extension rod, not shown, is attached to the rearward end of the plunger. The operator stands back 300 cm to 450 cm from the tap hole and the extension rod and plunger are then manipulated until the apex 40 of guide 38 is received in the tap hole H. The inclined surfaces of guide 38 centre the container in the tap hole as the container is pushed further into the tap hole opening until stop 70 abuts against the outer wall surface of the metallurgical vessel V (Figures 7 and 8) surrounding the tap hole H. The hole H has a diameter of about 15 cm (16 inches) and a length of about 120 cm (4 feet). Once the stop 70 abuts the wall, the container 10 will be located in its predetermined position, as illustrated in Figure 7. Because the container is of smaller diameter then the walls defining the tap hole an annular clearance is formed in between and the container may be readily and easily inserted into the tap hole notwithstanding local variations and irregularities in the surface of the walls defining tap hole H. To seal tap hole H, intermediate sleeve 56 is axially advanced relative to outer sleeve 52 and inner sleeve 54 as illustrated in Figure 8 to urge the wall 14 towards the wall 12. This ruptures the bag 27, helped by the serrated edge 32 and refractory mortar 26 within housing 30 is displaced out of aperture 34 in a direction generally radially of the container and substantially about its entire surface into the annular clearance and into sealing engagement with the walls of the tap hole. The mortar sets quickly, because of the heat. Once the mortar has set, the plunger may be rotated to unthread inner sleeve 54 from rod 20 and then be withdrawn from vessel V. The plug formed is located adjacent the inner surface 80 of the vessel in proper position adjacent the worn flared end 82 of the tap hole H and in sealing engagement with the walls defining the tap hole.

Claims: 1. A method of forming a plug in a tap hole (H) of a metallurgical vessel (V) by placing a mass of unhardened refractory mortar (26) in a metal container in the hole (H) and allowing or causing the mortar to harden characterised by placing the mortar (26) in a container (10) so dimensioned that when it is received in the hole (H) there is an annular clearance in between the container and the sidewalls defining the hole, and urging the mortar (26) out of the container (10) through an aperture (34) therein towards and into sealing engagement with the side walls of the hole (H). 2. A method according to Claim 1 characterised in that the aperture (34) extends radially of the container and towards the leading end of the container (10). 3. A method according to Claim 1 or 2 characterised in that the container (10) has a fixed leading end wall (12) and a movable trailing end wall (14), and the aperture (34) is present adjacent the fixed leading end wall (12), and in that the movable end wall (14) is urged towards the fixed end wall (12) to urge the mortar (26) out of the container (10). 4. A method according to any preceding Claim characterised in that the mortar (26) is located in a housing (30) extending between the end walls (12) and (14) but leaving a radial gap defining a circumferential radial aperture (34). 5. A method according to Claim 2, 3 or 4 characterised in that the mortar (26) is housed in a bag (27) and the free edge (32) of the housing (30) is serrated so that the serrated edge (32) breaks open the bag (27) when the movable end wall (14) is urged towards the fixed end wall (12). 6. A method according to any preceding Claim characterised in that a rod (20) extends from the fixed end wall (12) through the container (10) and beyond the movable end wall (14) and a plunger (50) having one part (54) to engage the fixed end wall (12) and another part (56) to abut the movable end wall (14) is connectable to the container (10) and in that the plunger (50) is connected to the rod (20) by the one part (54) and the assembly so formed is advanced towards the vessel (V), the container (10) is inserted into the hole (H) following which the other part (56) of the plunger (50) is actuated to urge the movable end wall (14) towards the fixed end wall (12) to urge the mortar (26) out of the container (10) and into the annular clearance between the container (10) and the sidewall of the hole (H). 7. A method according to Claim 6 characterised in that the projecting end of the rod (20) has a screw thread (22) which is releasably engaged by a threaded socket (74) formed in the one part (54) at the leading end of the plunger (50). 8. A method according to Claim 6 or 7 characterised in that the plunger (50) comprises three concentric sleeves (52, 54, 56), the outer (52) and inner (54) sleeves being secured together and the intermediate sleeve (56) being arranged for axial movement relative to the other sleeves (52, 54), the inner sleeve (54) having means (74) to engage the container (10) and the intermediate sleeve (56) having means (72) to act on the end wall (14) when the intermediate sleeve (56) is moved towards the container (10). 9. A method according to Claim 6, 7 or 8 characterised in that the plunger (50) includes a stop (70) located at a distance from the forward end (72) of the plunger (50) so that when the stop (70) is abutted against the outer face of the wall of the vessel (V), the container (10) extends into the hole (H) towards, but short of, the inner face (80) of the wall. 10. A container for use in forming a plug for a tap hole in a metallurgical vessel, the container (10) comprising a mass of a refractory mortar (26) in a metal container characterised in that a radial aperture (34) is present in a wall of the container (10) through which mortar (26) may pass. 11. A container according to Claim 10 characterised in that the container (10) has a fixed end wall (12) and a movable end wall (14) and the radial aperture (34) is present in the sidewall adjacent the fixed end wall (12). 12. A container according to Claim 10 or 11 characterised in that the refractory mortar (26) is housed in a bag (27) and the edge (32) of the wall (30) adjacent the aperture (34) is serrated. 13. A container according to Claim 10, 11 or 12 having a plunger (50) for use in forming a plug in a tap hole characterised in that the plunger (50) is formed of three concentric sleeves (52, 54 and 56), the outer sleeve (52) and the inner sleeve (54) being secured together (60), the forward end (72) of the outer sleeve (54) being arranged to engage the fixed end wall (12), the intermediate sleeve (56) being axially movable relative to the other sleeves and having at a forward end (74) means to engage the movable end wall (14) of the container (10), and an external stop (70) being located at a distance from the forward end (72) of the plunger (50).

Inventors: KOMANECKY, RICHARD JAMES
Applicants: FOSECO INTERNATIONAL LIMITED
Application year: 1988
Main classification: C21C5
IPC codes: C21C5, F27D3