Launder transfer insert and system

Abstract

An insert and system for removing molten metal from a vessel is disclosed. The insert defines an enclosed cavity, and includes a first opening in its side through which molten metal can enter the cavity, and a second opening at its top through which molten metal can exit the cavity. A trough at the top of the insert directs molten metal exiting the second opening out of the vessel. The system includes the insert and a molten metal pump that forces molten metal through the first opening and into the cavity.

Description

FIELD OF THE INVENTION

The invention relates to an insert for placing in a vessel to assist in transferring molten metal out of the vessel, and to a system utilizing the insert in combination with a molten metal pump.

BACKGROUND OF THE INVENTION

As used herein, the term “molten metal” means any metal or combination of metals in liquid form, such as aluminum, copper, iron, zinc and alloys thereof. The term “gas” means any gas or combination of gases, including argon, nitrogen, chlorine, fluorine, freon, and helium, that are released into molten metal.

Known molten-metal pumps include a pump base (also called a housing or casing), one or more inlets (an inlet being an opening in the housing to allow molten metal to enter a pump chamber), a pump chamber, which is an open area formed within the housing, and a discharge, which is a channel or conduit of any structure or type communicating with the pump chamber (in an axial pump the chamber and discharge may be the same structure or different areas of the same structure) leading from the pump chamber to an outlet, which is an opening formed in the exterior of the housing through which molten metal exits the casing. An impeller, also called a rotor, is mounted in the pump chamber and is connected to a drive system. The drive system is typically an impeller shaft connected to one end of a drive shaft, the other end of the drive shaft being connected to a motor. Often, the impeller shaft is comprised of graphite, the motor shaft is comprised of steel, and the two are connected by a coupling. As the motor turns the drive shaft, the drive shaft turns the impeller and the impeller pushes molten metal out of the pump chamber, through the discharge, out of the outlet and into the molten metal bath. Most molten metal pumps are gravity fed, wherein gravity forces molten metal through the inlet and into the pump chamber as the impeller pushes molten metal out of the pump chamber.

A number of submersible pumps used to pump molten metal (referred to herein as molten metal pumps) are known in the art. For example, U.S. Pat. No. 2,948,524 to Sweeney et al., U.S. Pat. No. 4,169,584 to Mangalick, U.S. Pat. No. 5,203,681 to Cooper, U.S. Pat. No. 6,093,000 to Cooper and U.S. Pat. No. 6,123,523 to Cooper, and U.S. Pat. No. 6,303,074 to Cooper, all disclose molten metal pumps. The disclosures of the patents to Cooper noted above are incorporated herein by reference. The term submersible means that when the pump is in use, its base is at least partially submerged in a bath of molten metal.

Three basic types of pumps for pumping molten metal, such as molten aluminum, are utilized: circulation pumps, transfer pumps and gas-release pumps. Circulation pumps are used to circulate the molten metal within a bath, thereby generally equalizing the temperature of the molten metal. Most often, circulation pumps are used in a reverbatory furnace having an external well. The well is usually an extension of the charging well where scrap metal is charged (i.e., added).

Transfer pumps are generally used to transfer molten metal from the external well of a reverbatory furnace to a different location such as a ladle or another furnace.

Gas-release pumps, such as gas-injection pumps, circulate molten metal while introducing a gas into the molten metal. In the purification of molten metals, particularly aluminum, it is frequently desired to remove dissolved gases such as hydrogen, or dissolved metals, such as magnesium. As is known by those skilled in the art, the removing of dissolved gas is known as “degassing” while the removal of magnesium is known as “demagging.” Gas-release pumps may be used for either of these purposes or for any other application for which it is desirable to introduce gas into molten metal.

Gas-release pumps generally include a gas-transfer conduit having a first end that is connected to a gas source and a second end submerged in the molten metal bath. Gas is introduced into the first end and is released from the second end into the molten metal. The gas may be released downstream of the pump chamber into either the pump discharge or a metal-transfer conduit extending from the discharge, or into a stream of molten metal exiting either the discharge or the metal-transfer conduit. Alternatively, gas may be released into the pump chamber or upstream of the pump chamber at a position where molten metal enters the pump chamber.

Generally, a degasser (also called a rotary degasser) includes (1) an impeller shaft having a first end, a second end and a passage for transferring gas, (2) an impeller, and (3) a drive source for rotating the impeller shaft and the impeller. The first end of the impeller shaft is connected to the drive source and to a gas source and the second end is connected to the connector of the impeller. Examples of rotary degassers are disclosed in U.S. Pat. No. 4,898,367 entitled “Dispersing Gas Into Molten Metal,” U.S. Pat. No. 5,678,807 entitled “Rotary Degassers,” and U.S. Pat. No. 6,689,310 to Cooper entitled “Molten Metal Degassing Device and Impellers Therefore,” filed May 12, 2000, the respective disclosures of which are incorporated herein by reference.

The materials forming the components that contact the molten metal bath should remain relatively stable in the bath. Structural refractory materials, such as graphite or ceramics, that are resistant to disintegration by corrosive attack from the molten metal may be used. As used herein “ceramics” or “ceramic” refers to any oxidized metal (including silicon) or carbon-based material, excluding graphite, capable of being used in the environment of a molten metal bath. “Graphite” means any type of graphite, whether or not chemically treated. Graphite is particularly suitable for being formed into pump components because it is (a) soft and relatively easy to machine, (b) not as brittle as ceramics and less prone to breakage, and (c) less expensive than ceramics.

Generally a scrap melter includes an impeller affixed to an end of a drive shaft, and a drive source attached to the other end of the drive shaft for rotating the shaft and the impeller. The movement of the impeller draws molten metal and scrap metal downward into the molten metal bath in order to melt the scrap. A circulation pump is preferably used in conjunction with the scrap melter to circulate the molten metal in order to maintain a relatively constant temperature within the molten metal. Scrap melters are disclosed in U.S. Pat. No. 4,598,899 to Cooper, U.S. patent application Ser. No. 09/649,190 to Cooper, filed Aug. 28, 2000, and U.S. Pat. No. 4,930,986 to Cooper, the respective disclosures of which are incorporated herein by reference.

SUMMARY OF THE INVENTION

The invention is an insert that is positioned in a vessel in order to assist in the transfer of molten metal out of the vessel. In one embodiment, the insert is an enclosed structure defining a cavity and having a first opening in the bottom half of its side and a second opening at the top. The insert further includes a launder structure (or trough) positioned at its top. Molten metal is forced into the first opening and raises the level of molten metal in the cavity until the molten metal passes through the second opening and into the launder structure, where it passes out of the vessel.

The insert can also be created by attaching or forming a secondary wall to a wall of the vessel, thus creating a cavity between the two walls. A first opening is formed in the secondary wall and a launder structure is positioned, or formed, at the top of the secondary wall and the wall of the vessel, so that a second opening is formed at the top. Molten metal is forced into the first opening and raises the level of molten metal in the cavity until the molten metal passes through the second opening and into the launder structure, where it passes out of the vessel.

A system according to the invention utilizes an insert and a molten metal pump, which is preferably a circulation pump, but could be a gas-injection (or gas-release) pump, to force (or move) molten metal through the first opening and into the cavity of the insert.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top, perspective view of a system according to the invention, wherein the system is installed in a vessel designed to contain molten metal.

FIG. 1A is another top, perspective view of a system according to FIG. 1.

FIG. 2 is a side, perspective view of an insert used with the system of the present invention.

FIG. 3 is a side, perspective view of the insert of FIG. 2 with an extension attached thereto.

FIG. 4 is a top, perspective view of an alternate system according to the invention.

FIG. 5 is a top view of the system of FIG. 4.

FIG. 6 is a partial, sectional view of the system shown in FIG. 5 taken along line C-C.

FIG. 7 is a side view of the insert shown in FIG. 2.

FIG. 8 is a top view of an alternate embodiment of the invention.

FIG. 9 is a partial sectional view of the system of FIG. 8 taken along line A-A.

FIG. 10 is a partial sectional view of the system of FIG. 8 taken along line B-B.

FIG. 11 is a close-up view of Section E of FIG. 10.

FIG. 12 is a partial sectional view of the system of FIG. 8 taken along line C-C.

FIG. 13 is an exploded view of the system of FIG. 8 showing an optional bracketing system.

FIG. 14 is a top, perspective view of the system of FIG. 13 positioned in a vessel.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawings, where the purpose is to describe a preferred embodiment of the invention and not to limit same, a system and insert according to the invention will be described. FIGS. 1-3 and 7 show a system 10 according to an aspect of the invention, and a vessel 1. Vessel 1 has a well 2, a top surface 3, a side surface 4, a floor 5, and a vessel well 6.

System 10 comprises a molten metal pump 20 and an insert 100. Pump 20 is preferably a circulation pump and can be any type of circulation pump satisfactory to move molten metal into the insert as described herein. The structure of circulator pumps is know to those skilled in the art and one preferred pump for use with the invention is called “The Mini,” manufactured by Molten Metal Equipment Innovations, Inc. of Middlefield, Ohio 44062, although any suitable pump may be used. The pump 20 preferably has a superstructure 22, a drive source 24 (which is most preferably a pneumatic motor) mounted on the superstructure 22, support posts 26, a drive shaft 28, and a pump base 30. The support posts 26 connect the superstructure 22 to the base 30 in order to support the superstructure 22.

Drive shaft 28 preferably includes a motor drive shaft (not shown) that extends downward from the motor and that is preferably comprised of steel, a rotor drive shaft 32, that is preferably comprised of graphite, or graphite coated with a ceramic, and a coupling (not shown) that connects the motor drive shaft to end 32B of rotor drive shaft 32.

The pump base 30 includes an inlet (not shown) at the top and/or bottom of the pump base, wherein the inlet is an opening that leads to a pump chamber (not shown), which is a cavity formed in the pump base. The pump chamber is connected to a tangential discharge, which is known in art, that leads to an outlet, which is an opening in the side wall 33 of the pump base. In the preferred embodiment, the side wall 33 of the pump base including the outlet has an extension 34 formed therein and the outlet is at the end of the extension. This configuration is shown in FIGS. 5, 9 and 10.

A rotor (not shown) is positioned in the pump chamber and is connected to an end of the rotor shaft 32A that is opposite the end of the rotor shaft 32B, which is connected to the coupling.

In operation, the motor rotates the drive shaft, which rotates the rotor. As the rotor (also called an impeller) rotates, it moves molten metal out of the pump chamber, through the discharge and through the outlet.

An insert 100 according to this aspect of the invention includes (a) an enclosed device 102 that can be placed into vessel well 2, and (b) a trough (or launder section) 200 positioned on top of device 102. Device 102 as shown (and best seen in FIGS. 2-3 and 5) is a generally rectangular structure, but can be of any suitable shape or size, wherein the size depends on the height and volume of the vessel well 3 into which device 102 is positioned. The device 102 and trough 200 are each preferably comprised of material capable of withstanding the heat and corrosive environment when exposed to molten metal (particularly molten aluminum). Most preferably the heat resistant material is a high temperature, castable cement, with a high silicon carbide content, such as ones manufactured by AP Green or Harbison Walker, each of which are part of ANH Refractory, based at 400 Fairway Drive, Moon Township, Pa. 15108, or Allied Materials. The cement is of a type know by those skilled in the art, and is cast in a conventional manner known to those skilled in the art.

Device 102 as shown has four sides 102A, 102B, 102C and 102D, a bottom surface 102E, and an inner cavity 104. Bottom surface 102E may be substantially flat, as shown in FIG. 2, or have one or more supports 102F, as shown in FIGS. 3 and 7.

Side 102B has a first opening 106 formed in its lower half, and preferably no more than 24″, or no more than 12″, and most preferably no more than 6″, from bottom surface 102E. First opening 106 can be of any suitable size and shape, and as shown has rounded sides 106A and 106B. First opening 106 functions to allow molten metal to pass through it and into cavity 104. Most preferably, opening 104 is configured to receive an extension 34 of base 30 of pump 10, as best seen in FIGS. 5, 9 and 10. In these embodiments, the outlet is formed at the end of the extension 34.

Device 102 has a second opening 108 formed in its top. Second opening 108 can be of any suitable size and shape to permit molten metal that enters the cavity 104 to move through the second opening 108 once the level of molten metal in cavity 104 becomes high enough.

Trough 200 is positioned at the top of device 102. Trough 200 has a back wall 202, side walls 204 and 206, and a bottom surface 208. Trough 200 defines a passage 210 through which molten metal can flow once it escapes through second opening 108 in device 102. The bottom surface 208 of trough 200 is preferably angled backwards towards second opening 108, at a preferred angle of 2°-5°, even though any suitable angle could be used. In this manner, any molten metal left in trough 200, once the motor 20 is shut off, will flow backward into opening 108. The bottom surface 208 could, alternatively, be level or be angled forwards away from opening 108. Trough 200 may also have a top cover, which is not shown in this embodiment.

In the embodiment shown in FIGS. 1-3 and 7, the trough 200 at the top of insert 100 is integrally formed with device 102. In a preferred method, after insert 100 is formed, the shape of the launder portion is machined into the top of device 102. Further, part of the front wall 102A is machined away so that trough 200 extends outward from wall 102A, as shown. Trough 200, however, in any embodiment according to the invention, can be formed or created in any suitable manner and could be a separately cast piece attached to device 102.

If trough 200 is a piece separate from device 102, it could be attached to device 102 by metal angle iron and/or brackets (which would preferably made of steel), although any suitable attachment mechanism may be used. Alternatively, or additionally, a separate trough 200 could be cemented to device 200.

An extension 250 is preferably attached to the end of trough 200. Extension 250 preferably has an outer, steel frame 252 about ¼″-⅜″ thick and the same refractory cement of which insert 100 is comprised is cast into frame 252 and cured, at a thickness of preferably ¾″-2½″. Brackets 260 are preferably welded onto frame 252 and these align with bracket 254 on trough 200. When the holes in brackets 260 align with the holes in bracket 254, bolts or other fasteners can be used to connect the extension 250 to the trough 200. Any suitable fasteners or fastening method, however, may be used. In one embodiment the bracket 254 is formed of ¼″ to ⅜″ thick angle iron, and brackets 260 are also ¼″ to ⅜″ thick iron or steel. Preferably, the surfaces of the refractory cement that from the trough and extension that come into contact with the molten metal are coated with boron nitride.

It is preferred that if brackets or metal structures of any type are attached to a piece of refractory material used in any embodiment of the invention, that bosses be placed at the proper positions in the refractory when the refractory piece is cast. Fasteners, such as bolts, are then received in the bosses.

An upper bracket 256 is attached to trough 200. Eyelets 258, which have threaded shafts that are received through upper bracket 256 and into bosses in the refractory (not shown), are used to lift the insert 100 into and out of vessel 1.

Positioning brackets 270 position insert 100 against an inner wall of vessel 1. The size, shape and type of positioning brackets, or other positioning devices, depend on the size and shape of the vessel, and several types of positioning structures could be used for each vessel/insert configuration. The various ones shown here are exemplary only. The positioning structures are usually formed of ⅜″ thick steel.

It is also preferred that the pump 20 be positioned such that extension 34 of base 30 is received in the first opening 100. This can be accomplished by simply positioning the pump in the proper position. Further the pump may be head in position by a bracket or clamp that holds the pump against the insert, and any suitable device may be used. For example, a piece of angle iron with holes formed in it may be aligned with a piece of angle iron with holes in it on the insert 100, and bolts could be placed through the holes to maintain the position of the pump 20 relative the insert 100.

In operation, when the motor is activated, molten metal is pumped out of the outlet through first opening 106, and into cavity 104. Cavity 104 fills with molten metal until it reaches the second opening 108, and escapes into the passage 210 of trough 200, where it passes out of vessel 1, and preferably into another vessel, such as the pot P shown, or into ingot molds, or other devices for retaining molten metal. Installation of the insert into a furnace that contains molten metal is preferably accomplished by pre-heating the insert to 300°-400° F. in an oven and then slowly lowering unit into the metal over a period of 1.5 to 2 hours.

In another embodiment of the invention shown in FIGS. 4-6, the insert 100 is replaced by a secondary wall 400 positioned in a different vessel, 1′, next to vessel wall 6′. Secondary wall 400 has a side surface 402 and a back surface 404 and is attached to vessel wall 7 by any suitable means, such as being separately formed and cemented to it, or being cast onto, or as part of, wall 6′. A cavity 406 is created between the wall 6′ of the vessel and secondary wall 400, and there is an opening (not shown) in secondary wall 400 leading to cavity 406. A launder 200′ is positioned on top of the cavity 406, and pump 10 is positioned so that its outlet is in fluid communication with the opening in secondary wall 400 so that molten metal will pass through the opening and into the cavity 406 when the pump is in operation. The trough 200 can be formed as a single piece and positioned on top of cavity 402, or it could be formed onto wall 7 along with secondary wall 400. Alternatively, a separate trough wall 408 could be separately formed and attached to the top of wall 6′ in such a manner as to seal against with the top surface of wall 6′ and the back section 404 of wall 400. In all other respects the system of this embodiment functions in the same manner as the previously described embodiment. This embodiment also includes extension 250 and can use any suitable attachment or positioning devices to position the insert and pump in a desired location in the vessel 1′.

Another embodiment of the invention is shown in FIGS. 8-12. This embodiment is the same as the one shown in FIGS. 1-3 and 7 except for a modification to the insert and the brackets used. This insert is the same as previously described insert 100 except that side 102A is not machined away. So, the trough 200 does not extend past side 102A.

FIGS. 8-10 show a bracket structure that hold pump 20 off of the floor of vessel 1″ (which has a different configuration than the previously described vessels). FIGS. 8-12, and particularly FIG. 11, show an alternate extension 250′. Extension is 250′ formed in the same manner as previously described extension 250, except that it has a layer 270′ of insulating concrete between ¼″ and 1″ thick between the steel outer shell 252′ and the cast refractory concrete layer 272′. This type of insulating cement is known to those skilled in the art. Eyelets are included in this embodiment and are received in bosses positioned in the refractory of the extension 250′.

In this embodiment, trough 200′ has a top cover 220′ held in place by members 222′. Extension 250′ has a top cover 290′ held in place by members 292′. The purpose of each top cover is to prevent heat from escaping and any suitable structure may be utilized. It is preferred that each top cover 220′ and 290′ be formed of heat-resistant material, such as refractory cement or graphite, and that members 222′ and 292′ are made of steel. As shown, a clamp 294′ holds member 292′ in place, although any suitable attachment mechanism may be used.

FIGS. 12 and 13 show the embodiment of the system represented in FIGS. 8-12, with an alternate bracing system to fit the vessel into which the system is being positioned. As previously mentioned, the bracing system is a matter of choice based on the size and shape of the vessel, and different bracing systems could be used for the same application. Another structure for aligning the pump 20 with insert 200′ is shown in FIG. 13 bar 400 is received in holders 420.

The support brackets are preferably attached to a steel structure of the furnace to prevent the insert from moving once it is in place. A locating pin on the steel frame allows for alignment of the outlet of the pump with the inlet hole at the bottom.

Having thus described some embodiments of the invention, other variations and embodiments that do not depart from the spirit of the invention will become apparent to those skilled in the art. The scope of the present invention is thus not limited to any particular embodiment, but is instead set forth in the appended claims and the legal equivalents thereof. Unless expressly stated in the written description or claims, the steps of any method recited in the claims may be performed in any order capable of yielding the desired result.

Claims

1. An insert for transferring molten metal out of a vessel, the insert for being used in combination with a molten metal pump having an outlet through which a stream of molten metal is generated, the insert defining an enclosed cavity and comprising: (i) one or more outer walls and a bottom;(ii) a first opening in the lower half of one of the one or more outer walls, the first opening leading to the enclosed cavity, the first opening being positioned so that it is in fluid communication with a discharge, such that at least part of the stream of molten metal exiting the discharge passes through the first opening and into the enclosed cavity;(iii) a second opening in a top of the insert; and(iv) a trough positioned at the top of the insert, the trough having a back wall that is positioned behind the second opening and that extends above the second opening and a first side wall positioned on one side of the second opening, and a second side wall positioned on the opposite side of the second opening, wherein the first wall and second side wall each extend above the second opening, the trough further including a bottom surface angled towards the second opening;

2. The insert of claim 1 that further includes an extension attached to the trough.

3. The insert of claim 1 wherein the trough is integrally formed on top of the insert device.

4. The insert of claim 1 wherein the insert has a front wall and the trough extends beyond the front wall.

5. The insert of claim 1 wherein the insert has a front wall and the trough does not extend beyond the front wall.

6. The insert of claim 1 that comprises refractory cement.

7. The insert of claim 1 that has a bottom and the first opening is no more than 12″ above the bottom.

8. The insert of claim 1 that has a bottom and the opening is no more than 6″ above the bottom.

9. The insert of claim 1 wherein the bottom surface of the trough is angled at 2°-5°.

10. The insert of claim 1 that includes at least two support sections extending from the bottom for resting on a floor of the vessel.

11. The insert of claim 1 wherein the trough has an end and there is an extension attached to the end of the trough.

12. A system comprising a molten metal pump, and an insert for transferring molten metal out of a vessel, the insert for being used in combination with a molten metal pump having an outlet through which a stream of molten metal is generated, the insert defining an enclosed cavity and comprising: (i) one or more outer walls and a bottom;(ii) a first opening in the lower half of one of the one or more outer walls, the first opening leading to the enclosed cavity, the first opening being positioned so that it is in fluid communication with a discharge, such that at least part of the stream of molten metal exiting the discharge passes through the first opening and into the enclosed cavity;(iii) a second opening in a top of the insert; and(iv) a trough positioned at the top of the insert, the trough having a back wall that is positioned behind the second opening and that extends above the second opening and a first side wall positioned on one side of the second opening, and a second side wall positioned on the opposite side of the second opening, wherein the first wall and second side wall each extend above the second opening, the trough further including a bottom surface;

13. The system of claim 12 wherein the molten metal pump is a circulation pump.

14. The system of claim 12 wherein the outlet of the molten metal pump is positioned ⅛″ or less from the first opening of the insert.

15. The system of claim 12 wherein the molten metal pump and the insert are attached.

16. The system of claim 12 wherein the molten metal pump has a base, and the base has an extension wherein the outlet is at the end of the extension, and the extension is received in the first opening of the insert.

17. The system of claim 12 wherein the insert further includes an extension attached to the trough.

18. The system of claim 12 wherein the trough is integrally formed on top of the insert.

19. The system of claim 12 wherein the insert has a front wall and the trough extends beyond the front wall.

20. The system of claim 12 wherein the insert has a front wall and the trough does not extend beyond the front wall.

21. The system of claim 12 wherein the insert comprises refractory cement.

22. The system of claim 12 wherein the insert has a bottom and the first opening is no more than 12″ above the bottom.

23. The system of claim 12 wherein the insert has a bottom and the opening is no more than 6″ above the bottom.

24. The system of claim 12 wherein the trough further includes a bottom surface angled towards the second opening.

25. The system of claim 24 wherein the bottom surface of the trough is angled at 2°-5°.

26. The system of claim 12 wherein the insert includes at least two support sections extending from the bottom for resting on a floor of the vessel.

27. The system of claim 12 wherein the trough has an end and there is an extension attached to the end of the trough.