Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B21/00—Obtaining aluminium
  • C22B21/0084—Obtaining aluminium melting and handling molten aluminium
  • C22B21/0092—Remelting scrap, skimmings or any secondary source aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
  • C22B9/16—Remelting metals
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• This invention relates to an improved method and apparatus for submerging, entraining, melting and circulating a metal charge in a molten media.
• a pump jamming problem is not an uncommon occurrence when there is an inadvertent inclusion of non-aluminum scrap, such as steel, in the scrap charged into the system.
• the non-aluminum scrap can become lodged between a pump impeller and the cooperating walls that surround the pump impeller thereby bringing the impeller to a stop.
• the walls and pump impeller are frequently damaged when this occurs.
• skim or dross in aluminum melting processes is an especially noxious problem due to the fact that the skim which is primarily aluminum oxide quickly forms due to the highly reactive nature of aluminum and the atmosphere enhanced by the presence of high temperatures of the molten metal.
• the pump impellers of each of the patents noted next above are positioned in close proximity to the walls that cooperate with the pump impeller to either enhance the pumping action or guide the molten aluminum carrying scrap to the pump.
• the problems of impeller pump jamming and skim generation though considered by the patentees noted above, has not been avoided. This is especially true in respect of jamming when a piece of non-meltable material such as refractory material having the same specific gravity as aluminum, and which therefore flows in the molten metal, is delivered to the pump portion of the system.
• this invention relates to a method and a system including apparatus for submerging, entraining, melting and circulating aluminum scrap in a molten metal media, which scrap is comprised of pieces not capable of self-submergence.
• the apparatus of the system includes means to introduce a supply of scrap into an open bay that has heated molten metal drawn from an entry point below the surface of the molten metal by the action of a molten metal scrap entrainment circulator
• the circulator continuously draws the heated molten metal including the scrap into the circulator wherein the scrap is completely entrained in the molten metal and delivered into a molten metal circulation path that delivers the scrap metal entrained in the molten metal for subsequent heating further melting the recirculation to the circulator.
• Another object of the invention is the provision of a molten metal " circulator that cooperates with a molten metal media in such a fashion that non-self-submerging scrap is drawn into the molten metal media and is melted.
• Yet another object of the invention is to provide a system in which there is a molten metal circulator that cooperates with a molten metal media and vertically disposed walls to thereby establish a fluid current path in the molten metal media which fluid current path causes the molten metal to move through the system.
• Still yet another object of the invention is to provide a furnace and molten metal holding bay that is simple in construction and easy to clean and service.
• FIG. 1 is a block diagram of a recirculating scrap melting system that embodies the invention.
• Figure 2 is a top plan view of the apparatus involved in the preferred embodiment of the invention.
• FIG. 3 is an elevational section taken along line 3-3 in Figure 2
• Figure 4 is a view along lines 4-4 in Figure 2
• Figure 5 is a three dimensional view of a molten metal, scrap entrainment circulator.
• Figure 6 is a view along line 6-6 in Figure 5,
• Figure 7 is a top plan view of a furnace, holding bay and molten media circulator system that embodies the invention.
• Figure 8 is a view along line 8-8 in Figure 7, and
• Figure 9 is a view along line 9-9 in Figure 7. Best Mode for Carrying Out the Invention
• FIG. 1 depicts in block diagram form, a recirculating scrap melting system that will embody the invention.
• the apparatus of the system includes a closed heating bay 11 and an open bay
• scrap and flux are introduced.
• a scrap entrainment molten metal circulator described more fully hereinafter positioned in the open bay 12 causes molten metal to circulate from the closed heating bay 11 into the open bay 12 as indicated by flow arrow 13.
• the molten metal is then circulated into the closed heating bay 11 as indicated by flow arrow 14.
• Scrap and flux are introduced at one end of the open bay 12 as indicated by flow arrow 16 and skim or dross is removed from the opposite end of the open bay 12 as indicated by flow arrow 17.
• the final product of the systems apparatus is skim free molten aluminum delivered from the closed heating bay 11 as indicated by flow arrow 15.
• FIG. 2 and Figure 3 illustrate respectively a top plan view and a front elevation sectional view showing the details of the preferred embodiment of the invention.
• FIG. 2 there is shown a closed heating bay 11 and an open bay 12.
• the closed heating bay and its details of construction are conventional in the sense that a cover 18 is positioned over the closed heating bay 11.
• the closed heating bay 11 and open bay 12 are constructed of refractory material. As best seen in
• FIG. 3 the refractory material is enclosed by a metal shell 19.
• the metal shell 19 is preferably steel.
• a pair of burners 21, 21a are shown directed downwardly into the heating bay 11.
• the nature and function of the burners 21, 21a is similar to burners currently used by industry. Only two burners are shown. It should be understood that the arrangement of burners and their number are a matter of design dependent on the type of burner available and the nature of the fuel employed in the combustion process.
• the open and closed bays 11, 12 are shown filled with a molten metal media 20, in the preferred embodiment the molten metal is aluminum.
• the open bay 12 is provided with a wall segment 22 formed of refractory material and integrally connected to a separating wall 23 that extends the length of both the closed heating bay 11 and the open bay 12.
• the open bay has end walls 24, 26 and front wall 27.
• the closed heating bay 11 has a back wall 28.
• the separating wall 23 has two openings 29, 31.
• the location of separating wall 23 openings 29, 31 are important to the operation of the system apparatus and the method involving the invention.
• a molten metal scrap entrainment circulator 32 is connected by a drive shaft 33 to a motor 34.
• the motor 34 may be an electric or any suitable motor the speed of which can be selected. It can be seen that the circulator 32 is positioned midway between the wall segment 22 and end wall 26.
• the opening 31 is also positioned midway between the wall segment 22 and end wall 26 at a point above the circulator 32 but beneath the surface 35 of the molten metal media 20.
• the relative locations, as shown, of the circulator 32, the opening 31 and wall segment 22, provide optimum performance for the method of the invention.
• the circulator 32 driven by motor 34 creates a fluid current path of molten metal.
• This molten metal path indicated by arrows not referenced draws molten metal through the opening 31 and circulates the molten metal through the open bay 12 and thence through opening 29 and back into the closed heating bay 11.
• molten metal path indicated by arrows not referenced draws molten metal through the opening 31 and circulates the molten metal through the open bay 12 and thence through opening 29 and back into the closed heating bay 11.
• all the walls of the heating and open bay are simple straight, vertically disposed walls which are easily and inexpensively formed of refractory material.
• the term inexpensive is intended to be a relative term which takes into account more sophisticated wall shapes of currently available scrap recycling systems noted earlier.
• the dynamic operation of the molten metal scrap entrainment circulator 32 will be explained more fully hereinafter.
• the opening 29 in separating wall 23 is located such that its lower side (not referenced) is flush with the floor 36 of the closed bay 11 and open bay 12.
• the location of the opening 29 is important from the standpoint that large and readily submersible scrap 37 sinks to the bottom of the open bay, is caught up in molten metal fluid current path generated by the circulator 32, and can be delivered to the closed heating bay 11 where the large pieces are melted. Practically speaking the submersible scrap 37 sinks to the bottom where much of it is melted in the position in which it comes to rest.
• the conveyor 39 carries scrap 41 that has by its nature a high surface area to volume ratio and ther efor e tends not to be self-submersible.
• Shr edded alumi num cans or entire cans , as well as small chips collected from manufactur ing operations are typical of non-self-submersible scrap .
• Non-self-submersible scrap in order to be drawn into the mol ten metal 20 must overcome the sur face tension of the layer of skim 40 that forms on molten metal 20.
• the non-self-submersible scrap 41 is introduced as shown into a mild vortex 42 created by the circulator 32.
• a severe vor tex is to be avoided because the severe vortex while drawing the non-self -submersible scrap into the molten metal also draws the surrounding atmospher e into the vortex ther eby greatly enhanc ing the f ormati on of skim which is a very undesirable by-product.
• the mild vortex 42 cooperates with the molten metal drawn through the opening 31 to thereby submerge the non-self-submerg ing scrap 41 into the molten metal 20.
• the circulator by its dynamic action to be described completely entrains the scrap 41 in the molten metal 20 where the scrap begins to be melted .
• the circulator 32 delivers molten metal with scrap entrained into a fluid curr ent path .
• the scrap is then melted by heat drawn from the flowing molten metal media during the passage through the open bay 12 and thus becomes part of the circulating molten media .
• the closed heating bay 11 has in its back wall 28 an opening 30 through which skim free molten aluminum is deliver ed .
• the opening 30 in back wall 28 is located at a point beneath the surface of the molten metal 20 such that any skim that is present in the closed heating bay 12 does not enter the finished mol ten metal 15 .
• the finished molten metal 15 overflows the heating bay 11 through the specially configur ed passage 30 at a rate substantially
• Flux supply 44 is shown delivering a fluxing agent into the mild vortex 42 as shown.
• Skim removal is accomplished as shown in Figure 3 by the provision of a ramped shaped top surface 25 at the top of end wall 24. As skim 40 forms and is moved by the action of the moving molten metal 20, it tends to build up on the ramp 25 where it may be removed manually or by an automated means not shown.
• FIG. 4 wherein reference numerals employed in respect of Figure 1 and Figure 3 are utilized to identify the same components.
• the molten metal scrap entrainment circulator 32 is shown in section in order to facilitate an explanation of the dynamics of its operation insofar as the circulator 32 acts upon the ' ' molten metal 20 to draw molten metal from the closed heating bay 11 through the opening 31 and into a central region 50 of the circulator 32.
• the fluid current path of molten metal from the closed heating bay 11 is shown by broken line arrows 51, 52.
• Non-self-submersible scrap 41 shown entering from above into the mild vortex 42 is caught in the current flow and drawn down into the central opening 50 of the circulator 32 where the scrap is completely entrained in the moving molten metal.
• the circulator 32 has vanes 53, 54 connected at an inner end to a frusto conical hub 56 shown in section. The scrap 41 entrained in molten metal is propelled outwardly along the vanes.
• FIG. 5 illustrates * in three dimensional form the molten metal scrap entrainment circulator 32.
• the circulator 32 is formed of refractory material and constructed by conventional techniques.
• the circulator has what may be termed a bottom plate 45 and a top plate 46.
• the top and bottom plates 45, 46 are spaced apart as shown and have integrally secured thereto a plurality of radially extending vanes 53, 54, 55, 56, 57 and 58.
• a frusto conical shaped hub 47 is integrally secured to the bottom plate 45 at the center thereof.
• the frusto conical hub 47 has a drive shaft 33 fitted into the hub 47 in a manner not shown.
• the height of the hub 47 is less than the distance between the top and bottom plates 46, 45.
• the vanes 53, 54, 55, 56, 57 and 58 at their inner radial ends are integrally secured to hub 47 at a point on the hub 47 outer surface between the top and bottom of the frusto conical hub as shown.
• the bottom radially extending edges of the vanes are secured to the bottom ..-- plate 45 and the outer ends of the vanes are secured to " • the top plate 46 as shown.
• the top plate 46 has a central circular opening 48, which circular opening 48 has a center axis coincident with the center axis of the drive shaft 33. It is important to the operation of the circulator 32 that inside diameter of the central circular opening 48 be greater than the outside diameter of the base of the frusto conical hub 47.
• a strong fluid flow current path as shown by arrow 68 draws molten metal delivered from the heating bay 11 as described earlier along with non-self-submersible scrap down into the circulator 32 where the scrap is completely entrained and then expelled outwardly towards the surrounding walls of the open bay 12 noted earlier.
• FIG. 6 illustrates the circulator 32 of Figure 5 in section.
• a foreign object 73 lodged in the central region o opening 50. It is a simple procedure to remove the object 73 by merely lifting the circulator 32 momentaril from the molten metal, after stopping the motor, and wit tongs removing the object 73.
• the circulator 32 of Figure 6 has formed in the bottom plate 45 thereof a grooved or notched portion 47a as shown. This groove 47a prevents cracking due to curing rate differences in different sections of the refractory casting of the circulator 32.
• FIG. 7 illustrates in a top plan view a furnace, holdinq bay and molten media circulator system that embodies this invention.
• the description up to this point has treated primarily the cooperative relationship of the molten metal or media circulator and the manner in which the circulator advantageously functions to entrain and melt scrap.
• Figures 7, 8 and 9 provide a detailed showing of additional features of the invention as the invention finds utility in a complete system.
• a closed heating bay 75 and a closed holding bay 85 More specifically there is shown a closed heating bay 75 and a closed holding bay 85.
• the heating bay 75 and holding bay 85 are formed in a common chamber defined by a front wall 76, a back wall 77, a cover 78, a first end 79, a second end 80 and finally a floor 81.
• the cover 78 is not shown in Figure 7.
• a dividing wall 82 separates a heating region in the heating bay 75 from a holding region in the holding bay 85.
• the dividing wall 82 has a number of passages 83, 84, 86 and 87 which provide for communication between the heating bay 75 and the holding bay 85.
• passages 83 and 84 allow molten media (not shown) to pass freely from the heating bay 75 to the holding bay 85.
• passages 86a, 86 and 87 allow combustion gases from the oil or gas treaters 88, 89 to move freely over the surface of the molten media from the heating bay 75 to the holding bay 85.
• the combustion or flue gases as the are termed are vented through a stack 91.
• a clean-ou ramp 92 which terminates at its upper end with a closure in the form of a guillotine door 93.
• the holding bay 85 also has a clean-out ramp 94 and guillotine door 95.
• Front wall 76 has openings 96, 97 through which molten media is circulated by molten media circulator 98 here shown schematically.
• the circulator 98 is shown positioned in an open bay 100.
• the open bay 100 has ski ramp 101 and wall section 102 as shown.
• a tapping spout 105 for molten metal or media is provided as shown in Figure 7.
• the tapping spout 105 is shown positioned such that a mold train 106 carried by rails 107, 108 can carry the molten metal or media away for subsequent processing.
• a heating bay and open bay drain spout 109 is positioned as shown.
• Skim pans 110, 111, 112 are shown carried by rails 113 , 114 .
• guillotine door 93 is important to the invention in that when this door 93 is opened, ready access can be had to service opening 96, 97, as well as passages 83, 84, 86 and 87.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Vertical, Hearth, Or Arc Furnaces (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)

Priority Applications (2)

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Publications (1)

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ID=22167829

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Cited By (5)

Families Citing this family (3)

Citations (2)

• 1982
  • 1982-02-23 JP JP82501103A patent/JPS59500008A/ja active Granted
  • 1982-02-23 WO PCT/US1982/000232 patent/WO1983002958A1/en unknown

Patent Citations (2)

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