Refractory head with optional spike for dross press

Abstract

A dross press head is constructed of refractory material. The refractory material may be a vitreous silica based refractory or other suitable refractory material including ceramic material. The refractory head may include reinforcing fibers, which may be stainless steel fibers. The refractory head may be provided with refractory clips or anchor bolts and secured at its upper end to a metal plate for structural strength. One or more spikes may be formed on or mounted to a lower surface of the refractory head for aiding flow of the upper layer of metal recovered from the dross. The spikes may be constructed of refractory material including ceramic material, cast steel, cast iron or hot rolled steel. Spike material may be selected based on the type of dross. The spike may be formed on the head threadably mounted to a supporting rod mounted to the upper metal plate.

Description

FIELD OF THE INVENTION

[0003] This invention is made in the field of dross pressing. More particularly, this invention is directed to an improved dross pressing head and related structure.

BACKGROUND OF THE INVENTION

[0004] The goal of dross pressing is to extract as much metal from the dross skim as possible while the dross is still hot. Metal in the dross that chills below the melting point before exiting the pot drain must be recovered at a secondary facility. By reducing the amount of metal units sent to a secondary processor, the final cost for recovering this metal can be saved.

[0005] Traditionally, materials used in manufacturing skim pots and heads that come into contact with dross are cast steel and mild (low-carbon) steel. These materials provide strength and stability during the dross compression process. However, it is been discovered that such materials may not provide the best thermal properties for the dross compression process.

[0006] During the dross pressing process, the dross is compacted between a press head and a skim pot. The pressing action forces free metal to migrate to points of lower pressure and towards the surfaces of the head and the pot. Metal is drained through a hole or holes in the skim pot. After pressing, the dross is called a skull. The skull normally consists of oxides and impurities surrounded by a sheet of metal on the inside where the head came into contact and on the outside where the dross touches the pot. The metal sheets are beneficial because they are made of what would have been small droplets of metal that easily oxidize in the secondary recovery process. The amount of metal that forms the sheets varies from dross to dross. If the amount of metal that forms these sheets can be reduced, the operator will benefit by recovering additional metal.

[0007] Each dross producer experiences different dross conditions. These conditions may range from dross near the freezing (solidification) temperature of the metal to a heavily thermiting (burning) reaction. In each case some amount of metal is trapped as a sheet between the head and the pressed skull.

SUMMARY OF THE INVENTION

[0008] In accordance with the present invention, there are many advantages of using a dross press head constructed of refractory material. The term “refractory material” herein throughout this description and the claims by definition includes ceramic material. One of the advantages of using a dross press head constructed of refractory material is that it does not have the tendency to chill the metal layer being formed by the dross pressing action. One disadvantage of the prior art heads made of steel and other metals is the tendency of the highly conductive metal to chill the molten metal being recovered from the dross as the press head comes into contact with this metal. Use of a refractory press head, as contrasted to a highly conductive metal head, can increase the draining through the skim pot opening of the recovered metal resulting from the pressing action.

[0009] Another advantage of a press head made of a refractory material is that it allows metal that would have become an inner sheet on the dross skull to run down to the bottom of the skull and out through a drain hole in the pot.

[0010] Briefly and basically in accordance with the present invention, a dross press head is made of a refractory material. In a presently preferred embodiment, the refractory material is a vitreous silica based refractory. Additionally, it is presently preferred that the refractory material be provided with reinforcing fibers and presently preferred reinforcing fibers are stainless steel fibers. Further, it is presently preferred that the refractory press head be mounted at its upper surface to a steel plate or platen for mounting to the press head piston. It is understood that other refractory materials and other reinforcing fibers may be utilized in practicing the present invention.

[0011] In another embodiment of the present invention, a spike may be provided on the lower surface of the refractory material. The spike may be manufactured from refractory material including ceramic material, cast steel, cast iron or hot rolled steel. The mounting of the spike may be fixed or permanently mounted to the refractory head or it may be removable. In a presently preferred embodiment, an opening may be provided in the refractory press head, a shaft is mounted to the upper steel plate and extends through the opening, and the spike is mounted to the lower end of the shaft. The spike may be removably mounted to the shaft by threads or other suitable means. However, it is understood that the spike may be permanently formed as a part of the refractory head, that is a projection of refractory material depending downwardly and positioned in mating relationship with a drain hole of the skim pot.

[0012] The spike provides an advantage of puncturing or forming a hole in the dross and allowing molten metal to drain more effectively from the pot, and this is particularly the case with respect to the upper layer of molten metal which is juxtaposed the head.

[0013] In a presently preferred method of practicing the invention, the spike material may be selected based upon the estimated temperature of the draining molten metal. Further, a spike may or may not be used depending upon the condition of the dross.

[0014] The refractory head in accordance with the present invention is suitable for many conditions ranging from cold dross to burning dross. The refractory head is especially effective for burning or thermiting dross. By pressing dross undergoing an exothermic reaction (thermiting) with a refractory head, as contrasted to a metal head, longer contact time may be achieved without damage to the head. Thermiting dross will attack a traditional steel head. A longer contact time under pressure, extinguishes thermiting by removing oxygen required for combustion.

[0015] An additional advantage of the refractory head of the present invention is that the head does not require any cooling such as forced air or water. A refractory head is an insulating or low heat conductive material, and is therefore slow to absorb heat. By extinguishing thermiting in this matter, the aluminum or other metal pressed from the dross is available for recovery, instead of being oxidized.

[0016] Another advantage of the refractory dross press head of the present invention is that it provides increased draining of recovered aluminum over that which would be achieved using a cast steel head, since the refractory head reduces or eliminates chilling of the small fine droplets of metal when they come into contact with the head.

[0017] Another advantage of the present invention is that the refractory head has a favorable useful life and increased durability over a metal head due to the fact that it does not absorb as much heat as a metal head. Therefore, the head is not subject to deterioration as a result of extreme heating and/or heating and cooling cycles. Further, the refractory head does not hold heat in a manner similar to a metal head.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] For the purpose of illustrating the invention, there are shown in the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

[0019] FIG. 1 is a plan view taken from above the metal plate or platen of a refractory head, showing the refractory head below the plate in dotted outline form.

[0020] FIG. 2 is a cross sectional view taken along line 2-2 of FIG. 1.

[0021] FIG. 3 is a cross sectional view of a refractory head taken along what would correspond to cross section line 2-2 of FIG. 1 of a refractory head with a spike.

[0022] FIG. 4-4 is a broken away cross sectional view taken along line 4-4 of FIG. 3.

[0023] FIG. 5 is a plan view taken from above an upper metal plate or platen of another embodiment of an oblong or elongated refractory head, where the refractory head is shown in dotted outline form.

[0024] FIG. 6 is a side elevation view of the oblong or elongated head structure of FIG. 5 illustrating in partial cross section a spike and its attachment structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Referring now to the drawings wherein like numerals indicate like elements, there is shown in FIG. 1 a top plan view of a refractory head 10 (shown in dotted outline) mounted to an upper metal plate or platen. Upper plate or platen 12 may be constructed of any suitable rigid material, but is preferably metal and preferably constructed of A36 steel.

[0026] Referring now to FIGS. 1 and 2 taken together, upper plate or platen 12 is provided with reinforcing structure 14, which may be suitable rectangular plates welded to the upper surface of upper plate 12. In the presently preferred embodiment, as illustrated FIG. 1, four reinforcing plates 14 are utilized, however various other numbers may be utilized such as two, three, five, six or any other suitable number. Centrally disposed on upper plate 12 is a connecting structure 16 comprised of a recess for receiving pressing piston rod 18 and a removable retaining pin 20.

[0027] Refractory head 10 is constructed of a refractory material. As stated above, refractory material includes ceramic material. The refractory material 10 is preferably a vitreous silica based refractory material. A presently preferred refractory material is currently available from Harbison-Walker Refractories Company, 600 Grant Street, Pittsburgh, Pa. 15219 under the designation Versaflow Thermax AL, S-0052-2, which is a vitreous silica based low cement casting mix with aluminum resistant additive. Although not required, it is preferred that the refractory material be provided with reinforcing fibers 11. Presently preferred reinforcing fibers are stainless steel (3000 series) fibers. However, it is understood that other suitable refractory materials and other suitable reinforcing fibers may be utilized in practicing the present invention.

[0028] The refractory head may be constructed of any suitable shape which mates with a suitably shaped skim pot. Referring now to FIGS. 1 and 2, there is shown a substantially semi-hemispherical shaped press head 10 which mates with a substantially semi-hemispherical skim pot 22. Skim pot 22 is mounted on tubular members 34 which may receive the forks of a fork lift truck for transporting the skim pot or collector to and from the dross compression apparatus. Refractory head 10 is provided with a plurality of ribs 24 which may be used to form creases or indentations in dross 26 as is now known in this art, see the teachings of the patents incorporated by reference. As described above, dross 26, after some pressing action, is comprised of an upper layer of metal 28, such as aluminum, juxtaposed refractory head 10. Dross includes an inner layer 30 of dross comprised of some aluminum, aluminum oxides and various other oxides, nitrates and carbides. The lower layer 32 is a layer of metal, such as aluminum, which is also expressed from the dross by pressing action. The dross press head normally presses or comes down a number of times during the processing of the dross, and in a presently preferred embodiment of practicing the invention, the dross press would make six cycles. It is understood that the present invention may be utilized for the extraction or recovery of various types of metals from dross, but it finds widespread use in the recovery of aluminum from aluminum dross.

[0029] In molding refractory head 10, the refractory material with the reinforcing fibers is molded with refractory clips or anchor bolts 36 extending through the upper surface of refractory head 10. Anchor bolts 36 are used to mount refractory head 10 to upper plate or platen 12. A suitably large number of such anchor bolts may be utilized to securely fasten refractory head 10 to upper plate 12. The lower ends of anchor bolts 36 are provided with flared lower ends 38. The flared lower ends may be any suitable flaring which enhances anchorage within the refractory material including multiple fingers, L-shapes or other suitable structure which enhance the retention of anchor bolts 36 within the refractory material. There is illustrated in one presently preferred embodiment, as shown in FIG. 1, the use of eight such anchor bolts or refractory clips to mount the refractory head 10 to plate 12. Other suitable means may be utilized to mount head 10 made of refractory material to the upper plate or platen 12.

[0030] Referring now to FIG. 3, there is shown another embodiment of the present invention wherein a refractory head is provided with a spike on its lower surface for enhancing flow of molten recovered metal through the opening in the skim pot. FIG. 3 is a view similar to FIG. 2 in that it would be taken along line 2-2 of FIG. 1 of a corresponding refractory head structure. Elements in FIG. 3 which remain unchanged from FIGS. 1 and 2 are assigned similar numbers and description thereof will not be repeated herein.

[0031] Referring particularly now to FIGS. 3 and 4, refractory head 40 may be constructed in a manner similar to that described with respect to FIGS. 1 and 2 of a suitable refractory material with or without suitable reinforcing fibers 41. In a like manner, refractory head 40 preferably is mounted via refractory clips or anchor bolts 36 to upper plate 12. Other suitable means may be utilized to mount refractory head 40 to plate 12. Refractory head 40 mates with skim pot 22 in a similar manner. A cross section of one of the ribs 24 is illustrated in the partial cross sectional view in FIG. 4.

[0032] Refractory head 40 is provided with an opening 42 which extends from the upper surface of refractory head 40 juxtaposed plate 12 to the lower surface 46 of refractory head 40. A shaft 44 is bolted or connected to upper plate 12 and extends through opening 42 to lower surface 46 of head 40. Mounted to the lower end of shaft 44 is spike 48. In a presently preferred embodiment, spike 48 is removably mounted to the lower end of shaft 44. Shaft 44 may be constructed of any suitable material, but is preferably constructed of steel. In a presently preferred embodiment, spike 48 may be threadably removably mounted to the lower end of shaft 44.

[0033] Spike 48 may be constructed of any suitable material, such as refractory material including ceramic material, cast steel, cast iron, hot rolled steel or the like. The refractory material utilized in the spike may be of the same type of refractory material utilized in heads 10 and 40, including the presently preferred vitreous silica based low cement casting mixed with aluminum resistant additive and the stainless steel (3000 series) reinforcing fibers. Preferably, the type of material utilized for the construction of spike 48 should preferably take into account the type of dross being processed, and particularly the anticipated temperature of the dross being processed. For example, it may be preferable to utilize a spike constructed of refractory material in the processing of thermiting dross whereas it may be desirable to select use of a spike constructed of steel or other suitable metal for processing dross anticipated to be at substantially the melting point of the metal to be recovered from the dross.

[0034] It is understood that shaft 44 and spike 48 may be of unitary construction. If spike 48 and shaft 44 are of unitary construction, the thread connection could be provided at plate 12 or the unitary element could be bolted to plate 12.

[0035] Alternatively, spike 48 may be formed integrally with refractory head 40. It other words, spike 48 may be an extension of the refractory material in the form of a spike projecting downwardly from the lower surface 24 of refractory head 40 in a position suitable to pass at least partially through drain hole 49 of skim pot 22. As may be seen in FIG. 3, spike 48 enhances the ability of upper layer 60 of molten metal (often aluminum) to flow downwardly and out through drain hole 49 of skim pot 22.

[0036] Referring now to FIGS. 5 and 6, there is shown a refractory head 50 having an elongated or substantially oblong shape mounted to a corresponding upper plate or platen 52. FIG. 5 is a plan view of upper plate 52. FIGS. 5 and 6 do not show the refractory clips or anchor bolts similar to anchor bolts 36, reinforcing plates similar to plates 14 and the piston rod and piston rod connecting structure. Typically, in an oblong head two spaced piston heads may be utilized in a manner to that shown and disclosed in U.S. Pat. No. 5,669,957—Roth, which has been incorporated herein by reference. Refractory head 50 may be comprised of refractory material, including any reinforcing fibers, as described with respect to FIGS. 1 through 4, including the preferred embodiments thereof. As illustrated in FIG. 6 in cross section, a spike 58 may be provided. Preferably, a single spike may be utilized as shown in FIG. 6, although it is understood that more than one spike may be utilized for a skim pot having a plurality of drain holes. As illustrated in FIG. 6, spike 58 may be removably mounted to a shaft 54 mounted to plate 52 and extending through an opening in refractory head 50. As described above, all of the arrangements of providing a spike may be utilized including a unitary spike and shaft arrangement or a spike formed directly on the refractory head.

[0037] In view of the above, the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

Claims

1. In a dross press, an apparatus comprising a dross press head constructed of refractory material.

2. An apparatus in accordance with claim 1 wherein said refractory material is constructed of a vitreous based silica.

3. An apparatus in accordance with claim 1 wherein said refractory material is provided with reinforcing fibers.

4. An apparatus in accordance with claim 3 wherein said reinforcing fibers are stainless steel.

5. An apparatus in accordance with claim 1 wherein said dross press head is of a substantially semi-hemispherical shape.

6. An apparatus in accordance with claim 1 wherein said dross press head is substantially oblong in shape.

7. An apparatus in accordance with claim 1 wherein said refractory material is constructed of a ceramic material.

8. An apparatus in accordance with claim 1 wherein said dross press head is provided with a spike positioned on a lower surface of said dross press head.

9. An apparatus in accordance with claim 8 wherein said spike is constructed of a refractory material.

10. An apparatus in accordance with claim 8 wherein said spike is constructed of a refractory material having a vitreous silica base.

11. An apparatus in accordance with claim 8 wherein said spike is constructed of a refractory material which is a ceramic.

12. An apparatus in accordance with claim 8 wherein said spike is constructed of cast steel.

13. An apparatus in accordance with claim 8 wherein said spike is constructed of hot rolled steel.

14. An apparatus in accordance with claim 1 wherein said dross press head constructed of refractory material is secured to an upper plate.

15. An apparatus in accordance with claim 14 wherein said refractory material of said dross press head is secured to said upper plate by bolts mounted in said refractory material with a flared lower end.

16. An apparatus in accordance with claim 15 wherein said dross press head is provided with an opening extending from said upper plate to a lower surface of said head, a shaft being mounted in said opening and secured to said upper plate, and a spike mounted to a lower end of said shaft.

17. An apparatus in accordance with claim 16 wherein said spike is threadably mounted to said shaft.

18. In a dross press, an apparatus, comprising: a dross press head constructed of a refractory material; and a spike projecting downwardly from said dross press head.

19. An apparatus in accordance with claim 18 including a skim pot, said skim pot having a drain hole in a lower portion thereof, said spike being positioned on said head and adapted to pass into said drain hole upon lowering of said head into said skim pot.

20. An apparatus in accordance with claim 18 wherein said spike is constructed of a refractory material.

21. An apparatus in accordance with claim 18 wherein said spike is constructed of a refractory material having a vitreous silica base.

22. An apparatus in accordance with claim 18 wherein said spike is constructed of a refractory material which is a ceramic.

23. An apparatus in accordance with claim 18 wherein said spike is constructed of cast steel.

24. An apparatus in accordance with claim 18 wherein said spike is constructed of hot rolled steel.

25. An apparatus in accordance with claim 18 wherein said head is constructed of a vitreous based silica.

26. An apparatus in accordance with claim 18 wherein said spike is constructed of a vitreous based refractory material having stainless steel reinforcing fibers.

27. An apparatus in accordance with claim 18 wherein said dross press head is of a substantially semi-hemispherical shape.

28. An apparatus in accordance with claim 18 wherein said dross press head is substantially oblong in shape.

29. An apparatus in accordance with claim 18 wherein said dross press head constructed of refractory material is secured to an upper plate.

30. An apparatus in accordance with claim 29 wherein said refractory material of said dross press head is secured to said upper plate by bolts mounted in said refractory material with a flared lower area.

31. An apparatus in accordance with claim 18 wherein said spike is selected to be constructed of a refractory material or a metal based upon the type of dross to be pressed.

32. An apparatus in accordance with claim 31 wherein said spike is selected to be constructed of refractory material for use in connection with thermiting dross.

33. An apparatus in accordance with claim 31 wherein said spike is selected to be constructed of refractory material for use in connection with dross anticipated to be substantially at the melting temperature of the metal to be recovered.