US3776534A

US3776534A - Degassing of slag coated melt

Info

Publication number: US3776534A
Application number: US00254162A
Authority: US
Inventors: R Cashdollar
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-05-17
Filing date: 1972-05-17
Publication date: 1973-12-04
Anticipated expiration: 1990-12-04

Abstract

There is disclosed a degassing process and degassing apparatus incorporating a slag-breaker which instead of being an integral welded unit is formed of several parts which are readily stored and readily transported and are secured together by fasteners at the site of use. The slag-breaker includes a tapered member in the form of a conical receptacle and a top for this member. The slag-breaker is assembled near the degassing vessel, the top being secured substantially below the rim of the member. The slag-breaker is secured to the gas entrance or snorkel of the vessel with the rim of the tapered member above the opening in the snorkel.

Description

United States atet [191 Cashdollar, Sr.

[ DEGASSING OF SLAG COATED MELT [76] Inventor: Robert E. Cashdollar, Sr., R.D. N0.

7, Butler, Pa.

[22] Filed: May 17, 1972 21 Appl. No.: 254,162

[57] ABSTRACT There is disclosed a degassing process and degassing apparatus incorporating a slag-breaker which instead of being an integral welded unit is formed of several parts which are readily stored and readily transported and are secured together by fasteners at the site of use. The slag-breaker includes a tapered member in the form of a conical receptacle and a top for this member. The slag-breaker is assembled near the degassing vessel, the top being secured substantially below the rim of the member. The slag-breaker is secured to the gas entrance or snorkel of the vessel with the rim of the tapered member above the opening in the snorkel.

6 Claims, 6 Drawing Figures PATENIEDUEB 4 I975 sum 1 or 2 PRIOR ART FIG.5

PATENTEDUEC 41975 SHEEIZM 2 FIGA DEGASSING OF SLAG COATED MELT BACKGROUND OF THE INVENTION This invention relates to the making of steel and has particular relationship to the degassing of the melt in the making of steel. The degassing is a purification step which is introduced in the making of certain grades of steel particularly by the basic-oxygen process. In continuous casting the degassing precedes the pouring of the steel into the chill mold of the casting line.

In the degassing step the snorkel or gas-entranceopening of a degassing vessel is injected into the melt in a ladle. The ladel and vessel are moved vertically, one relative to the other, as the vessel is exhausted. The gas from the melt flows through the vessel and out through the exhaust openings. The vessel is composed of metal, lined internally with refractory brick. Typically, the cost of relining a vessel may be as high as $120,000.00.

The surface of the melt is coated with slag and the penetration of the slag into the degassing vessel to any substantial extent results in rapid deterioration of the refractory brick and demands relining of the vessel. A slag-breaker is provided to reduce the penetration of the slag into the vessel.

In accordance with the teachings of the prior art the slag-breaker is an integral welded conical unit of steel in the form of a closed receptacle which is mounted over the mouth or opening of the snorkel with a guiding shell extending from its top into the opening. Typically, the slag-breaker is a cone having a diameter of about four feet and a height or altitude of about one and onehalf feet. The prior-art slag-breaker includes a rod or bar which extends laterally from the conical member. This bar is engaged by wires to secure the slag-breaker to the outer surface of the snorkel. The breaker extends part way across the end of the snorkel and IMOWOOL sealing material or the like is interposed between the breaker and the end. When the snorkel first penetrates into the melt the slag-breaker deflects the slag away from the snorkel reducing the absorption of slag into the opening of the snorkel. The slag-breaker is fused into the melt but it is contemplated that the lateral walls of the snorkel prevent the slag from penetrating into the opening in the snorkel after the slag-breaker is fused.

Because of its awkward structure, the prior-art slagbreaker is not readily stored or shipped. It is readily damaged during shipment or while in storage. Its movement from one place to another is costly because, not only does it occupy a large volume on the shipping vehicle, but it also must be moved by hand to and from the vehicle. In addition, in use it leaves much to be desired in reducing the flow of slag into the opening in the snorkel.

SUMMARY OF THE INVENTION This invention arises from the realization that the prior-art slag-breakers are not satisfactorily effective in reducing the flow of slag into the degassing vessel because they are held by means of the rods against the end of the snorkel in a position exposing a substantial part of the end of the snorkel to the slag as the snorkel enters the melt. The slag moves along the end penetrating between the sealing material and the end and wearing a filet in the end around the opening. As the filet becomes larger, in repeated use of the vessel, more and more slag penetrates through the opening in the snorkel into the vessel ultimately requiring replacement of the refractory brick.

It has been discovered that this undesirable functioning of the slag-breaker can be eliminated by eliminating the suspension rods and at the same time the transporting and warehousing difiiculties and the high shipping cost which the prior-an slag-breakers impose are also ameliorated. In addition, the cost of making the slagbreaker is materially reduced.

In accordance with this invention the slag-breaker, instead of being an integrated welded unit, is composed of separate parts; a tapered member in the form of a receptacle and a top. The rods are dispensed with. Instead, the rim of the tapered member extends above the outer end of the snorkel and is directly secured to the outer wall of the snorkel. The rim of the tapered member thus extends above the entrance opening in the snorkel and the penetration of slag into this opening is sharply reduced. The parts according to this invention are shipped and warehoused separately and when used are removed to the site of the degassing vessel and bolted together near the degassing vessel before being mounted on the snorkel. The tapered parts when separate may be nested so that a large number may be shipped and warehoused in relatively small spaces. These parts need not be moved manually; they can be moved by a hoist or fork-lift. The cost of welding the top to the tapered member is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of this invention, both as to its organization and as to its method of operation, together with additional objects and advantages thereof, reference is made to the following description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a view partly in side elevation and partly in section showing degassing apparatus in accordance with this invention;

FIG. 2 is a view in section showing a slag-breaker, in accordance with this invention, as it is integrated into degassing apparatus;

FIG. 3 is a view in side elevation showing how tapered members of a slag-breaker in accordance with this invention are transported and stored;

FIG. 4 is a view in side elevation showing how the tops of slag-breakers in accordance with this invention are transported and stored;

FIG. 5 is a fragmental view partly in section showing in detail the manner in which a slag-breaker in accordance with this invention is mounted on the snorkel; and

FIG. 6 is a fragmental view partly in section showing in detail how a slag-breaker in accordance with the teachings of the prior art is mounted on a snorkel and how such slag-breaker operates in deflecting the slag.

DETAILED DESCRIPTION OF INVENTION nected. The vessel 11 also includes a snorkel 27 having by means of which the slag-breaker is secured in sealing relationship with the opening 29. Only two such diametral openings 49 and wires 51 are shown but there may be more than two suspensions, typically four spaced 90 around the member 41.

The tapered member 41 and top 43 are secured together by fasteners 53. Each fastener 53 includes a bolt 55 which passes through the member 41 and top at an angle and is secured by a nut 57 or Dzus or other kindred fastener. The bolthead firmly engages a washer 59 spanning internally the tapered member and the end of the plate 45. The top 43 is secured a substantial distance below the upper rim 61 of the member 41. While only two diametral fasteners 53 are shown, there may be more than two such fasteners 53, for example, four spaced 90 around the vessel 41.

During transportation or in storage the tapered members 41 may be nested on a pallet 63, as shown in FIG. 3, and the tops 43 may be stacked on a pallet 65, as shown in FIG. 4. A large number of slag-breaker parts may be handled in this way.

In use the slag-breaker 13, with the

parts

41 and 43 secured together by the fastener 53, is mounted on the snorkel 27 by the wire 51. An annular strip 67 of sealing material, such as KAOWOOL, is compressed between the plate 45 and the end of the snorkel 27. The ladle 17 is placed on the platform and the hydraulic drive (not shown) of the platform is energized to raise the ladle 17 so that the snorkel 27 with the slag breaker 13 on its end penetrates into the melt 19. The slagbreaker 13 deflects the slag 21. Since the rim 61 of the member 41 is above the opening 29, the slag is prevented from penetrating under the end of the snorkel 27 when the snorkel 27 first enters the melt 19. The slag-breaker 13 melts, but the outer wall of the snorkel keeps the slag 21 away from the opening 29 and minimizes the flow of slag into the opening 29 and the formation of a filet on the inner corner 69 of the snorkel. The hydraulic drive (not shown) moves the melt 19 upwardly and downwardly relative to the snorkel 27 and the degassing proceeds.

In the prior-art structure of the slag-breaker 71 (FIG. 6) the wire 73 engages rods 75 to hold the plate 77 in compressing relationship with the sealing material 67. But a substantial portion 79 of the end of the snorkel 27 extends beyond the slag-breaker 71. As the snorkel 27 and slag-breaker 71 move into the melt 19, the slag 81 under the end 79 penetrates through the sealing material 67 producing ever growing filet 83.

While a preferred embodiment and practice of this invention has been disclosed herein, many modifications thereof are feasible. This invention is not to be re stricted except insofar as is necessitated by the spirit of the prior art.

I Claim:

1. In the degassing, with a degassing vessel during the making of steel, of a melt over whose surface a layer of slag extends, the said vessel having an entranceopening means including an opening through which said melt including the gas therein flows into the degassing vessel, the method of minimizing the slag from said layer which penetrates into said vessel through said opening means, which comprises providing a tapered member in the shape of a receptacle having a hollow surface and tapering from a cross-sectional region of larger area to a cross-sectional region of substantially smaller area, providing, separately, a top for said member, said top including a plate and a shell extending from said plate, said members being readily nested and said tops being readily stacked, securing said top and member to said opening means with said top secured to the inner surface of said member and said shell extending into said entrance opening and with the tapered surface of said member extending into said melt with said region of larger cross-sectional area outwardly of said melt, so as to deflect the slag away from said opening means, said plate and the portion of said receptacle from the region of smaller area to the region where the plate is secured defining a closed volume, and interposing sealing material in the region bounded by said en'- trance means, the surface of said plate outwardly of said volume, and the outer surface of said shell.

2. A slag-breaker including a generally tapered member in the form of a receptacle tapering from a region of small cross-sectional area to a rim, a separable top for said tapered member, said top including a plate having a shell extending from said plate fastener means securing said top to the inner surface of said tapered member, said top being secured to the inner surface of said tapered member a substantial distance inwardly of the rim of said tapered member, said plate and the portion of said receptacle between said plate and said region of small cross-sectional area defining a closed volume, said shell extending from said plate outwardly of said volume, said member being provided along its rim with openings for securing the breaker to entranceopening means of a degassing vessel.

3. Liquid metal treating apparatus including a deg assing vessel for degassing a melt over whose surface slag extends, said degassing vessel having entrance-opening means having entrance-opening means for entrance of said melt, a slag-breaker including a generally tapered member in the form of a receptacle and tapering from a rim to a termination of substantially smaller crosssectional area than said rim and a separable top for said member including a plate and a shell extending from said plate, fastener means for securing said top internally to said member a-substantial distance inwardly of the rim, said plate and the portion of said member between said plate and said termination of smaller crosssectional area defining a closed volume, and said shell extending from said plate outwardly of said volume, means securing said slag-breaker to said entrance opening means so that the part of said member between the top and the rim extends over said opening of said entrance-opening means so as to substantially reduce the penetration of said slag into said vessel and said shell extends into said entrance-opening means, and sealing material interposed in the region bounded by said entrance-opening means, the portion of said plate outwardly of said shell and the outer surface of said shell.

4. The combination of claim 3 wherein the slagbreaker securing means includes suspensions connected directly to the member and to the entranceopening means.

5. The method of claim 1, for carrying out a plurality of degassing operations, in whose practice, preparatory to their successive assembly for a degassing operation, a plurality of the members are nested and a plurality of tops for the respective members are stacked.

6. In the degassing, with a degassing vessel during the making of steel, of melts over each of whose surfaces a layer of slag extends, the said vessel having an entrance-opening means with an opening through which each melt including the gas therein flows into the degassing vessel, the method of minimizing the slag from said layers which penetrates into said vessel through said opening; the said method comprising providing a plurality of tapered members of generally conical form having external surfaces lending themselves readily to nesting, each said member having openings near its rim for suspending said last-named member, providing a plurality of tops for said members, each top including a plate from which a shell extends, said tops lending themselves readily to stacking, preparatory to the use of said members for minimizing said slag penetration, nesting a plurality of said tapered members and stacking a corresponding plurality of said tops, preparatory to the degassing of a melt, securing a said top to a corresponding said member internally of said last-named member with the shell of said last-named top away from the apex of said last-named member and the said openings of said last-named member rim-ward of the last-named top, and by means of suspensions engaging said last-named openings, suspending said last-named member from said entrance-opening means, with said last-named shell penetrating into said opening of said opening means and with sealing material in the region defined by said opening means outwardly of said opening, the portion of said top outwardly of said shell and the contiguous external surface of said shell.

Claims

1. In the degassing, with a degassing vessel during the making of steel, of a melt over whose surface a layer of slag extends, the said vessel having an entrance-opening means including an opening through which said melt including the gas therein flows into the degassing vessel, the method of minimizing the slag from said layer which penetrates into said vessel through said opening means, which comprises providing a tapered member in the shape of a receptacle having a hollow surface and tapering from a crosssectional region of larger area to a cross-sectional region of substantially smaller area, providing, separately, a top for said member, said top including a plate and a shell extending from said plate, said members being readily nested and said tops being readily stacked, securing said top and member to said opening means with said top secured to the inner surface of said member and said shell extending into said entrance opening and with the tapered surface of said member extending into said melt with said region of larger cross-sectional area outwardly of said melt, so as to deflect the slag away from said opening means, said plate and the portion of said receptacle from the region of smaller area to the region where the plate is secured defining a closed volume, and interposing sealing material in the region bounded by said entrance means, the surface of said plate outwardly of said volume, and the outer surface of said shell.

2. A slag-breaker including a generally tapered member in the form of a receptacle tapering from a region of small cross-sectional area to a rim, a separable top for said tapered member, said top including a plate having a shell extending from said plate fastener means securing said top to the inner surface of said tapered member, said top being secured to the inner surface of said tapered member a substantial distance inwardly of the rim of said tapered member, said plate and the portion of said receptacle between said plate and said region of small cross-sectional area defining a closed volume, said shell extending from said plate outwardly of said volume, said member being provided along its rim with openings for securing the breaker to entrance-opening means of a degassing vessel.

3. Liquid metal treating apparatus including a degassing vessel for degassing a melt over whose surface slag extends, said degassing vessel having entrance-opening means having entrance-opening means for entrance of said melt, a slag-breaker including a generally tapered member in the form of a receptacle and tapering from a rim to a termination of substantially smaller cross-sectional area than said rim and a separable top for said member including a plate and a shell extending from said plate, fastener means for securing said top internally to said member a substantial distance inwardly of the rim, said plate and the portion of said member between said plate and said termination of smaller cross-sectional area defining a closed volume, and said shell extending from said plate outwardly of said volume, means securing said slag-breaker to said entrance opening means so that the part of said member between the top and the rim extends over said opening of said entrance-opening means so as to substantially reduce the penetration of said slag into said vessel and said shell extends into said entrance-opening means, and sealing material interposed in the region bounded by said entrance-opening means, the portion of said plate outwardly of said shell and the outer surface of said shell.

4. The combination of claim 3 wherein the slag-breaker securing means includes suspensions connected directly to the member and to the entrance-opening means.