Patent Publication Number: US-2007102853-A1

Title: Dross compression apparatus including a cooling system for cooling the compression head and cooling method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation-in-part of U.S. patent application Ser. No. 10/778,456, filed Feb. 13, 2004, which claims the benefit of U.S. Provisional Application Ser. No. 60/518,547, filed Nov. 7, 2003, the disclosures of which are herein incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION  
      This invention relates to a dross compression apparatus and more particularly to a cooling system and cooling method for more effectively cooling the compression head of a dross compression apparatus.  
     BACKGROUND OF THE INVENTION  
      Dross compression apparatus are commonly used to recover non-ferrous metals, particularly aluminum, from dross which has been skimmed from a furnace. Aluminum dross is a combination of aluminum metal and aluminum oxides, as well as other possible components such as various oxides, nitrates and carbides. Aluminum dross is a by-product of an aluminum melting operation. Generally the dross floats on top of the molten aluminum metal in the furnace. Aluminum dross may contain anywhere from ten percent to ninety percent aluminum depending on the particular processing technique and the type of furnace. Therefore the dross in an aluminum melting operation includes a significant amount of aluminum metal which is considered a valuable resource to be recovered.  
      The recovery of aluminum from aluminum dross must also address the problem of the loss of aluminum metal in the dross due to thermiting or thermite reaction, i.e., exothermic oxidation of aluminum metal. It is generally known to provide the compression head of the dross compression apparatus with air or water cooling to reduce the thermiting action and thereby increase the amount of aluminum recovered from the aluminum dross. However, there is a continuing need to be able to remove heat more effectively from the dross compression head to increase the capacity of the dross compression apparatus in recovering aluminum from aluminum dross or other non-ferrous metals from other drosses without the use of water cooling.  
     SUMMARY OF THE INVENTION  
      The compression head of the dross compression apparatus is more effectively cooled in accordance with the present invention by blowing cooling air across the top of the compression head during the recovery of various non-ferrous metals including aluminum from various types of dross.  
      In accordance with one aspect of the invention, one or more air nozzles are provided for directing cooling air across the top of the compression head.  
      In accordance with another aspect of the invention, one or more air vents are provided in the dross compression apparatus for venting the air after being directed across the top of the compression head.  
      In accordance with another aspect of the invention, a plurality of ribs may extend across the top of the compression head in the direction of the air vents for directing the air out of the air vents after being directed across the top of the compression head.  
      In accordance with another aspect of the invention, the air nozzles may direct air along and between the ribs on the top of the compression head toward the air vents.  
      In accordance with another aspect of the invention, the air nozzles may be movable in synchronism with the compression head during vertical movement of the compression head toward and away from the dross collector.  
      These and other objects, advantages, features and aspects of the present invention will become apparent as the following description proceeds.  
      To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principles of the invention may be employed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In the annexed drawings:  
       FIG. 1  is a schematic front elevation view of the dross compression apparatus of the present invention showing air vent slots in a back wall of the apparatus.  
       FIG. 2  is a schematic fragmentary side elevation view of the dross compression apparatus of  FIG. 1  showing air nozzles connected to an air manifold for blowing air across cooling ribs on the top of the compression head and out air vent slots in a wall of the apparatus.  
       FIG. 3  is a schematic top plan view of the compression head and air manifold with air nozzles connected thereto of  FIG. 2 .  
       FIG. 4  is a front elevation view of the compression head of  FIGS. 2 and 3 .  
       FIG. 5  is an enlarged schematic perspective view of the air manifold and air nozzles of  FIGS. 2 and 3 .  
       FIG. 6  is a schematic side elevation view of one form of dross compression apparatus of the present invention.  
       FIG. 7  is a schematic back elevation view of the dross compression apparatus of  FIG. 6 .  
       FIG. 8  is a schematic top plan view of the dross compression apparatus of  FIG. 6 .  
       FIG. 9  is a perspective view of a cooling system in accordance with one exemplary embodiment of the present invention.  
       FIG. 10  is a perspective view of a cooling system in accordance with another exemplary embodiment of the present invention.  
       FIG. 11  is a perspective view of a multi-chamber cooling system in accordance with another exemplary embodiment of the present invention.  
       FIG. 12  is a perspective view of a cooling system in accordance with another exemplary embodiment of the present invention.  
       FIG. 13  is a front view of a cooling head in accordance with an exemplary embodiment of the present invention.  
       FIG. 14  is a front view of a cooling system in accordance with an exemplary embodiment of the present invention where a skim pot and a sow mold are shown in section.  
       FIG. 15  is a side view of a cooling head in accordance with another exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring now in detail to the drawings wherein like reference numerals are used to indicate like parts, and initially to  FIG. 1 , there is schematically shown one form of dross compression apparatus  1  in accordance with the present invention which may be generally of the type disclosed in U.S. Pat. Nos. 5,397,104 and 5,669,957, the entire disclosures of which are incorporated herein by reference. Such apparatus includes a compression head  2  that may be driven vertically by a suitable drive means such as a fluid piston/cylinder  3  toward and away from a dross collector  4 . Alternatively, the drive means may drive the dross collector  4  toward and away from the compression head  2  or drive both the compression head and dross collector toward and away from one another. Any suitable drive means may be utilized for this purpose including hydraulic, pneumatic, electrical or other drive means.  
      Dross collector  4  may have a substantially hemispheric shaped receptacle  5  and compression head  2  may be similarly shaped to cooperate with the receptacle. The term substantially hemispheric shaped as used herein is broadly defined to mean any shape that is substantially similar in concept and function to the shapes shown in the drawings and includes shapes that deviate from the shapes shown such as flatter structures or more pointed structures as well as structures that may have additional curved surfaces.  
      The dross collector receptacle  5  is provided with one or more openings (not shown) at the bottom of the receptacle to allow molten aluminum (or other molten metal) to pass by gravity and under the pressure of compression head  2  out from the collector into a lower receptacle  6  which is referred to in the art as a sow mold. Dross collector  4  may be provided with tubular members  7  for receipt of the forks of a forklift truck for transporting the dross collector  4  from a furnace to the dross compression apparatus and removal therefrom.  
      The compression head  2  of the present invention may be made of any suitable solid metal such as cast alloy steel to provide sufficient mass for dissipating heat in the dross metal during the recovery of various non-ferrous metals from various types of dross, including particularly aluminum from dross which has been skimmed from a furnace. Multiple ribs  10 - 12  may be provided on the top  15 , bottom  16  and sides  17  of the compression head as schematically shown in  FIGS. 2-4 . As used herein, the term rib means broadly any projection or shape which forms a projection, raised area, ridge, corner or non-continuity on the compression head.  
      The ribs  11  and  12  on the bottom  16  and sides  17  of compression head  2  extend into the dross in the dross collector or skim box  4  during the recovery process to help dissipate the heat in the dross metal. Also such ribs may help increase the compressive force on the dross metal as disclosed in the aforementioned U.S. Pat. Nos. 5,397,104 and 5,669,957.  
      The ribs  10  on the top  15  of compression head  2  also help to remove heat from the compression head. To remove heat more effectively from the compression head, cooling air may be blown across the top of the compression head during and between relative vertical movements of the compression head and dross collector toward and away from each other. These ribs  10  extend generally in the same direction, for example, from the front of the apparatus toward the back, to help channel cooling air that is blown across the top of compression head  2  out through air vent slots  18  (see  FIGS. 1-3  and  7 ) in a wall  19  of the dross compression apparatus.  
      Cooling air may be directed along the peaks  20  and valleys  21  of ribs  10  by a plurality of vortex nozzles  22  supported by an air manifold  23 . If the compression head is mounted for vertical movement, the air manifold  23  and associated air nozzles  22  may be raised and lowered in synchronism with the raising and lowering of the compression head  2  so that the air is always directed across the top of the compression head and not onto the dross metal which would cause the dross metal to oxidize.  
      Suitable slides or the like (not shown) may be provided on the air manifold  23  for engagement with vertical rails or the like on the frame of the dross compression apparatus for guiding the air manifold during its vertical movement. Also a suitable mechanism such as a piston/cylinder  25  that is used to move the air manifold  23  vertically may be controlled by the same controller  26  (see  FIGS. 7 and 8 ) that is used to control the vertical movements of the compression head  2  for causing the air manifold and associated air nozzles  22  to move in unison with the compression head.  
      Suitable hoses  30  may connect the air nozzles  22  to the plenum chamber  31  of the air manifold  23  as schematically shown in  FIG. 5 . Air manifold  23  may be supplied with pressurized air through a hose  32  from a suitable air supply such as compressed air or air received from a blower at a remote site.  
      The number, size and location of the air vent slots  18  in wall  19  of dross compression apparatus  1  should be such that substantially all of the cooling air passing over the top of the compression head is discharged through the slots to minimize oxidation of the dross metal. Air vent slots  18  may all be of about the same length and may match the peaks  20  and valleys  21  formed by the ribs  10  on the top of compression head  2  in number and location. If the wall  19  of dross compression apparatus  1  in which the slots are provided contains a small door  35  used to provide access for cleaning the compression head, the slots  18  may also extend through portions of the door as schematically shown in  FIG. 7  to aid in the venting of substantially all of the cooling air from the dross compression apparatus after passing over the top of the compression head.  
      In operation in accordance with the method of the present invention, dross is collected from an electric furnace or the like in the receptacle  5  of the dross collector  4  and then transported to the dross compression apparatus  1 . With the lower receptacle or sow mold  6  in place, metal, particularly aluminum, is allowed to decant through an opening in the lower end of the dross collector  4  into the sow mold. Then, after the main door  36  (see  FIG. 8 ) of the dross compression apparatus is closed, the compression head  2  is moved toward the dross collector receptacle  5  to compress the dross. At the same time, the ribs  11  and  12  on the bottom  16  and sides  17  of the compression head  2  form grooves in the shell of material between the compression head and the inner surface of the receptacle as disclosed in the aforementioned U.S. Pat. Nos. 5,397,104 and 5,669,957 enabling the shell to be easily broken for further processing such as by crushing.  
      The cooling air that is directed by the vortex nozzles  22  across the top of the compression head  2  during compression of the dross will lower the temperature of the compression head and maximize the cooling effect of the air on the compression head. Removing the heat from the compression head while the compression head is compressing the dross material during the recovery process increases the capacity of the dross compression apparatus without the need for water cooling. The cooling capacity of the compression head of the present invention may be as much as four times that of a standard compression head. For example, a dross compression apparatus incorporating the compression head cooling system of the present invention that normally presses three to four containers of dross metal every three to four hours would be able to press three to four containers of the dross metal every hour.  
      With reference to  FIGS. 9 through 15 , various exemplary embodiments of a cooling system  37  are shown. The cooling system  37  may be used to cool a variety of materials including, for example, aluminum dross, dross from other metal processing, salt cake and so forth. The material may be residue obtain following the recovery of molten aluminum from a recycling operation or from some other industrial process, such as, without limitation, byproducts from a magnesium processing system and chloride flux derived from a paper pulp processing system. As will be appreciated, these materials are preferably cooled prior to disposal or further processing.  
      The cooling system  37  includes a cooling head  38 . The cooling head  38  may be placed on a material container  39 . The cooling head  38  and material container  39  have corresponding geometries to cooperate with one another in the manners described herein. Depending on the application, the material container  39  may be referred to as a dross collector (e.g., the dross collector  4  of  FIGS. 1 and 6 - 7 ), a skim pot, and so forth. The cooling head  38  and/or the material container  39  may be made from any appropriate material, including cast alloy steel or grey iron. Grey iron may be cheaper than alloy steel, but alloy steel may be more resistant to surface checking and cracking and, as a result, have a longer life-span. Allow steel also may more efficiently cool the material.  
      The material container  39  may have a receptacle  40  for the material to be cooled. In the embodiment of  FIG. 11 , the material container  39  has plural receptacles  40 . In one embodiment, the receptacle  40  and/or a portion of the cooling head  38  that projects into the receptacle  40  may be substantially hemispheric shaped. Of course, other shapes are possible.  
      In some configurations, the material container  39  may be provided with one or more openings  41  (best shown in  FIG. 14 ) at the bottom of the receptacle  40  to allow molten aluminum (or other flowable material) to pass by gravity and/or under the pressure from the cooling head  38 . The substance passing through the openings  41  mat be collected in a collector pan  42  disposed under the material container  39 . Depending on the industrial application, the collector pan  42  may be referred to as a drain pan or a sow mold.  
      The material container  39  and/or the collector pan  42  may include passages  43  that accept forks of a forklift truck for transporting the material container  39  and/or collector pan  42 . In one embodiment, the cooling head  38  may include tubular members  44  for receipt of the forks of a forklift truck for transporting the cooling head  38  and/or positioning the cooling head  38  on the material container  39 . In another embodiment, the cooling head  38  may be wider than the material container  39  and the forks of the forklift truck may move and/or position the cooling head  38  by engaging portions of the cooling head  38  that overhand the material container  39 . In yet other embodiments, the cooling head  38  may be moved and/or positioned with respect to the material container  39  using a hoist or crane. The cooling head  38  may include a hook(s), ring(s) or other member for facilitating coupling of the cooling head  38  to the hoist or crane by way of, for example, a rigid member, a cable, a chain, a hook, and so forth. In one embodiment, such as the embodiment shown in  FIG. 12 , the cooling head  38  may be coupled to a lever arm  45 . The lever arm  45  may be raised and lowered (and possibly swung) to position the cooling head  38  with respect to the material container  39 . In the illustrated embodiment, the elevation of the lever arm  45  is controlled by a hydraulic piston, but other mechanisms for positioning the lever arm  45  are possible. The lever arm  45  may connect directly to the cooling head  38  or may connect to the cooling head  38  by way of a rigid member, a cable, a chain, a hook, a ball joint, a spring and/or some other member. The lever arm  45  may be mounted to a stationary frame.  
      The cooling head  38  may have a downwardly projecting protrusion  47 . As illustrated, a plate-like member that forms an upper portion  48  of the cooling head  38  has a depression, or well, that forms the protrusion  47  by protruding downwardly for making thermal contact with the material. The upper surface of the upper portion  48  may be depressed so that the lower surface of the protrusion  47  is convexly curved and is disposed below the surrounding flange-like members formed by the upper portion  48 . In some embodiments, the protrusion  47  may be substantially hemispheric shaped. When the cooling head  38  is positioned on the material container  39 , the protrusion  47  may enter the receptacle  40  though an open top of the material container  39  and the protrusion  47  may contact the material contained in the material container  39 . The cooling head  38  may include multiple protrusions  47 , such as a protrusion  47  for each receptacle  40  of a multi-receptacle  40  material container  39  (e.g., the cooling head  38  and the material container  39  of  FIG. 11 ).  
      Heat from material contained in the material container  39  may be transferred to the protrusion  47 . A substantial amount of the transferred heat may be conveyed to the upper portion  48  of the cooling head  38 . In one embodiment, the upper portion  48  of the cooling head  38  may be a plate that surrounds the protrusion  47 . In the illustrated embodiments, the upper portion  48  is open so that a recess formed by the protrusion  47  is open to the environment. This open recess, or well, creates surface area for efficient heat transfer and provides a lighter cooling head  38  relative to a cooling head  38  that has a solid protrusion  47  or a covered protrusion  47 . The surface of the well (which is the upper surface of the protrusion  47 ) may be relatively smooth as shown or have structural elements (e.g., ribs).  
      The lower surface of the protrusion  47  may be relatively smooth as shown in  FIGS. 9 through 12 . Alternatively, the lower surface of the protrusion  47  may have structural elements, such as ribs  49  as shown in  FIGS. 13-15 . Again, as used herein, the term rib means broadly any projection or shape which forms a projection, raised area, ridge, corner or non-continuity on a surface. Ribs also may be referred to as fins or flanges. Similar to the ribs  11 - 12 , the ribs  49  may extend into the material in the material container  39  to help dissipate and/or transfer the heat in the material. Also, such ribs may help increase the compressive force on the material. In the exemplary embodiments of  FIGS. 9-15 , the cooling head  38  is placed on the material container  39  and any compression of the material in the material container  39  is achieved solely by the weight of the cooling head  37  acting on the material. In other embodiments, downward force may be applied to the cooling head  38  to achieve compression of the material. Such downward force may be applied, for example, using a press assembly, such as the above-described dross compression apparatus  1 . In other embodiments, downward force may be applied by a forklift truck or the lever arm  45  used to move the cooling head  38 .  
      To assist in dissipating and/or radiating heat from the material to the environment, the cooling head  38  may include structural elements on the upper surface of the upper portion  48 . For instance a series of ribs  50  may be present. The tubular member  44 , if present, also may serve to assist in dissipating and/or radiating heat. In effect, the ribs  50  and/or other elements on the top of the cooling head  38  may help to remove heat from the cooling head  28 . To enhance the removal of heat from the cooling head  38 , cooling air may be directed across the top of the cooling head  38 . For instance, as shown in  FIG. 10 , a blower  51  or other ventilation system may draw air across the top of the cooling head  38  as graphically portrayed by arrow  52 . In other embodiments, the air may be blown across the top of the cooling head  38 . Plural cooling systems  37  may be arranged in close proximity to each other such that air may be directed across multiple cooling heads  38  to assist in cooling material that is dispensed into multiple corresponding material containers  39 .  
      The ribs  50  on the cooling head  38  may extend generally in the same direction, such as from the front of the cooling head  38  toward the back of the cooling head  38  (e.g., as shown in  FIGS. 9-10  and  12 - 15 ) or from one side to another side (e.g., as shown in  FIG. 11 ). The directionality of the ribs may help channel cooling air that is directed across the top of the cooling head  38 . For instance, cooling air may be directed along the peaks  53  and valleys  54  of the ribs  50  as best illustrated in  FIGS. 13 and 14 . Any suitable nozzle assembly, blower, manifold, fan or air circulator may be used to create an air flow to assist in removing heat from the cooling head  38 . If the cooling head  38  is mounted for vertical movement, such as when used as a compression head for a compression apparatus, the air directing mechanism may be raised and lowered in synchronism with the raising and lowering of the cooling head  38 .  
      A lower surface of upper portion  48  may be configured to engage an upper edge of material container  39 . The interface (or closure) between the cooling head  38  and material container  39  may reduce the flow of gasses into the receptacle and reduce oxidation of the material in the material container  39  during cooling. As indicated, edge portions of the upper portion  48  may overhang the material container  39 . Overhanging portions  55  may be bent downward to enhance the sealing effect, to divert air flow and/or to provide a lip to assist in stabilizing the cooling head  38  in embodiments where a forklift is used to lift the underside of the cooling head  38 . The downwardly bend overhanging portions  55  may be present on any combination of the front edge, the rear edge, the left side edge and the right side edge.  
      The well formed by the protrusion  47  may be filled with a material to assist in weighting the cooling head  38  and/or adjusting the cooling behavior of the cooling head  38 . For instance, sand, metal shot, plates or a conforming metal insert may be placed in the well. Also, a cooling apparatus may be placed in the well. In other embodiments a coolant (in addition to or instead of the above-described air) may be directed across the surface of the recess and/or the ribs  50 . For instance, water or oil may be circulated with respect to the cooling head  38 .  
      In an exemplary industrial application to process aluminum dross, a compression apparatus (e.g., the compression apparatus  1 ) may be used to compress dross in a time period of about an hour or less. Then, the container in which the dross was compressed may be moved from the compression apparatus and a cooling head (e.g., the cooling head  38 ) may be placed on the moved dross and dross container to further cool the dross for a period of time, such as about one hour to about two hours. This allows for increased use of the compression apparatus for compression, which leads to increased throughput and process efficiencies.  
      Although the invention has been shown and described with respect to certain embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. In particular, with regard to the various functions performed by the above described components, the terms (including any reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed component which performs the function in the herein illustrated exemplary embodiments of the invention. Also, all of the disclosed functions may be computerized and automated as desired. In addition, while a particular feature of the invention may have been disclosed with respect to only one embodiment, such feature may be combined with one or more other features as may be desired and advantageous for any given or particular application.