US2947527A - Device for insufflating gas into a mass of molten metal - Google Patents

Description

United States Patent DEVICE FOR INSUFFLATING GAS INTO A MASS OF MOLTEN METAL Filed Sept. 9, 1957, Ser. No. 682,850

5 Claims. (Cl. 266-34) This inventionrelates to devices for insufllating gas into a mass of molten metal and more particularly to a package-plug for attachment to a ladle or other vessel, for this purpose.

Many attempts have been made to blow gas into masses of molten metal. This has been done, for example, by a lancing process in which a lance is thrust into the top surface of the metal. It has been done, by constructing a large part of a wall of a vessel of a porous material. It has also been done by permanently attaching a plug to the base of a vessel as an actual part of thevessel by leaving a relatively large opening in the vessel which the plug fills.

These devices all have their disadvantages. The type in which the Vessel has an opening filled by a porous plug is capable of carrying out the metallurgical operation to which the plug assembly of the present invention relates, but it has the disadvantage that the vessel has to be modified quite a lot to attach the plug. And, attachment and detachment is difiicult since the plug and its attributes are part of a more or less permanent structure on the vessel.

A pplicants development Having regard to the disadvantages of the prior devices the applicant has now developed a package-plug which exists as a self-contained unit and can be applied to a vessel which need only have a small opening in its wall to receive a gas admission tube.

Briefly, this unit is made up of a frustroconical difiusing plug of porous refractory material including a tapering side wall and opposed large and small end walls for receiving gas and for contacting the molten metal respectively. A housing surrounds the plug. The housing includes a tapering wall which encases in gas-tight relationship the tapering side wall of the plug and projects beyond its large end to provide a skirt. An end assembly on the plug includes a base wall connected to the skirt and forms with the skirt and the large end of the plug an enclosure constituting a gas chamber. An outwardly projecting connectingstem connected to and extending through the base isadapted to extend through an opening in'the wall of the metallurgical vessel for connecting the package unit to the vessel. The connecting stem includes a gas passage for conveying gas from outside the vessel into the gas chamber. Retaining means acts between the base wall and the large end of the plug to retain the plug in wedging'nested relationship against the tapered wall.

According to one construction the connecting tube acts both as a support for the plug and as a conduit for conveying gas into the gas chamber.

According to another form of the invention, the threaded tube merely acts as a conduit and for connecting the plug to the vessel and does not act in a plug-supporting capacity. For supporting the plug, separate supporting members, for example screws are provided, extending through the base of the plug and bearing against a support which in turn bears against the refractory plug.

Detailed description The invention has thus been generally described and will now be referred to in more detail by reference to the accompanying drawings in which: 1

Figure 1 is a side elevation, partly in section, of a ladle equipped according to the invention.

Figure 2 is a vertical cross-section partly in elevation through the package-plug of the invention, removably attached to the ladle of Figure 1.

Figure 3 is a vertical cross-section through an alternative form of package-plug according to the invention.

More particular reference will now be made to the drawings. In the general arrangement of Figure 1, the ladle A is shown rotatably mounted on a bale 15. In accordance with the invention, the bottom wall of the dadle is provided with a relatively small opening 17 and a refractory lining C. The refractory lining C is provided with a plug-surrounding part 19 having a cavity 21 in which is mounted a package-plug B according to theinvention. The portion 19 of the refractory lining C of the ladle is a different refractory from the general refractory lining.

As shown in detail in Figure 2, the package-plug B is made up of a frustroconical refractory porous plug 31 having a small face 31a adapted to contact molten metal in the ladle and a larger'face 31b adapted to receive gas. The plug 31 is encased in a frustro conical metal casing 35 which has a wall extending beyond the face 31b of the plug to form a skirt 37. Welded to the skirt 37 is a circular base plate 39. t l i The casing 35 and plate 39 are preferably of plain carbon steel, when molten steel is to be blown. 'In the case of copper-bearing metal it would be advantageous to use a casing material of a different analysis, for example, Monel metal. Welded to the base 39 is a hub tapped on the inside as as 41a. This hub projects downwards through the opening 17 as shown. The hub 41 receives a threaded tube 45. The tube 45 is provided with agas outlet opening 46. The tube 45 is screwed into the hub 41 to a point where it bears against the plate 47 which in turn bears against the surface 31b of the plug 31. .A nut 49 and washer, on the tube 45, are employed to clamp the package plug against the base of the ladle. A nipple 55 is screwed on to the bottom of the tube 45 and connects to a gas line 57 which leads to a gas cylinder 59in the particular form of the invention shown. It should be understood however that this is only one way of feeding gas and the gas line 57 could lead to a separate source of gas supply. The skirt 35, plate 39 and face 31b define a gas chamber for supplying gas to the plug 31.

The base plate 39 is welded to the tube 45 as at "48. The base plate 39 may also be welded to the bottom of the vessel as at 50. These two welds serve to prevent escape of gas from the chamber formed between the base plate 39, the plug face 31b and the casing 35. r a

Operation In operation, the package plug is fitted to the vessel, that is, to the ladle A substantially as shown in Figures 1 and 2. The vessel is filled with molten metal, for example, steel. The gas supply is turned on and gas fed through the line 57 to the gas chamber beneath the plug, and the gas diffuses up through the plug and into the molten metal in small bubbles which rise up through the molten mass and carry out the desired metallurgical effect.

Alternative form An alternative form of the package-plug is shown in Figure 3. The numbers given to this plug have the same tens and digits, but, for parts which correspond to parts on the plugs shown on Figures 1 and 2 have been raised by to avoid confusion with the parts of the latter.

In this alternative form, the tube 145 is fixedly connected to the base 139 of the package-plug and extends down below it. In this particular form the tube 145 plays no part in holding the plug 131 in place in its casing.

For Supporting the plug 131, a perforated metal plate 147 is acted on by four supporting screws 146, 146a, 146b, 146a. These screws are each screwed into a tapped opening 148, 148a, etc, in the, base 139.. When they have been screwed into position to bear against the plate 147, they are welded in place as at 150. A weld is also applied between the tube 145 and the base plate 139 as at 152 or 154 or both. The casing or skirt 135 is welded to the base plate 139 around the circumference of the device at 155.

This alternative form of device is simpler in construction and in application than the form shown in Figures land 2. Further, the gas has a, freer entry to the gas chamber because the tube 145 is merely a supply tube and does not serve also as a support for the plug 131. The tube 145 is threaded, however, to receive a bolt and washer for clamping purposes.

The selection of appropriate materials from which various'parts of the apparatus are made will present no problem to one skilled in the art. For example, the metal casing 35 may be of sheet steel or other suitable metal as may be the base plate 39. The plug B is of a porous refractory material which is capable of forming a self-supporting plug, is sufiiciently porous to allow permeation of gas but not sufliciently porous to allow the metal to enter the pores. The refractory C is of a type normally used for lining ladles and similar vessels While the refractory 19 is a refractory which can be packed about the plug.

This application is a continuation-in-part of application Serial Number 267,439, filed January 21, 1952, now Patent 2,811,346.

I claim:

1. A self-contained unit for removable attachment to the inside of the bottom wall of a metallurgical vessel for blowing gas into the vessels molten contents, said bottom wall being provided with a connecting opening, comprising a fnlstro-conical diffusing plug of porous refractory material including a tapering side wall and opposed large and small end walls for receiving gas and for contacting the molten metal respectively, a metal housing including a side wall encasing in gas-tight relationship to the tapering side wall of the plug and projecting beyond said large end thereof to provide an integral skirt, and an end assembly including a flat metal base wall welded gas tightly to the skirt and forming with the skirt and said largeend of the plug and enclosure constituting a gas chamber, an outwardly projecting connecting stem connected to said base wall, said base wall being adapted to seat on the inside of said vessel bottom wall with said connecting stem extending through the opening in the wall of the metallurgical vessel for connecting the unit to the vessel, said connecting stern including a gas passage therethrough for conveying gas from outside the vessel into V in the stem.

said gas chamber, and adjustable retaining means acting between said base wall and the large end of the plug to retain the plug in wedging-nested relationship against said tapered wall, said retaining means extending through the base wall whereby it is accessible for adjustment from outside the unit.

2. A self-contained unit according to claim 1, in which the base wall is provided with a tapped opening, and said retaining means includes a stress distributing suppermember bearing against a. major portion of the large end of the plug, and a screw-threaded member engages in said tapped opening and bears against said support member.

3. A unit according to claim 1, in which the connecting stem is a tube fixedly attached in an opening in said base wall and extending outwardly therefrom, said tube being threaded for screwing into a tapped opening in the vessel, said retaining means including a plate bearing against the large end of the plug, and a plurality of set-screws engaging in tapped openings in said base wall and bearing against said plate.

4. A self-contained unit as defined in claim 1 in which said tapering side wall is of sheet metal of substantially the. same thickness throughout its length and said base wall is of sheet metal.

5. A metallurgical apparatus for insufliating gas into a body of molten metal comprising in combination a metallurgical vessel for containing the molten metal, a gas source, said vessel, aving a bottom wall provided with a connecting opening, a frustro-conical gas diffusing plug of porous refractory material including a tapering side wall, a large end wall for receiving the gas and a smaller opposed end wall for contacting the molten, metal, a housing including a tapering side wall encasing in gastight relationship the tapering side wall of the plugand projecting beyond the large end thereof to provide an integral skirt, and an end assembly including a base. wall permanently connected to the skirt and forming with the skirt and said large end of the plug an enclosure constituting a gas chamber, an outwardly projecting connection stem connected to said base, said base wall seating on the inside of said vessel bottom wall with said stem extending through the connecting opening of the vessel, said stem having a gas passage therethrough for conveying the gas from outside the vessel into said gas chamber, retaining means acting between the base wall and the large end of the plug to retain the plug in wedging-nested relationship against the tapered wall, means outside the bottom wall of the vessel co-operating with said stem to clamp said base wall against said bottom wall of the vessel, and means connected to said connecting stern exteriorly of said vessel to lead said gas from the gas source to the gas passage References Cited in the file of this patent FOREIGN PATENTS

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