Abstract:
A metal melting closed furnace which includes a main chamber, a circulation wall connected to the main chamber by a communications passageway and a vortex well having a exit outlet for molten metal into the main chamber. A cover is emplaced over the vortex well. An inert gas bubble activated molten metal pump is provided in which there is an entry port in the circulation well and exit port tangentially arranged with respect to the periphery of the cavity. This exit port will typically be at or near the top of the vortex well. In order to reduce oxidation, inert gas bubbles are captured from this molten metal pump and are transported to an inert gas atmosphere or blanket above the molten metal vortex.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Technical Field  
           [0002]    The present invention relates to metallurgical processes and apparatus, and more particularly to metallurgical processes and apparatus in which metal chips are melted in a molten metal vortex which is fed by an inert gas bubble-actuated molten metal pump.  
           [0003]    2. Technical Background  
           [0004]    My following U.S. patents disclose various apparatus and processes related to the introduction of metal chips into the charge-well of a metal melting furnace and the conveyance of molten metal from one place to another within or out of a metal melting furnace.  
           [0005]    U.S. Pat. No. 4,710,126 discloses a process for producing dry metal chips. This process includes the steps of entraining fluid-containing metal chips in a gas, introducing the gas into a cyclone separator having an internal wall heated to fluid-vaporizing temperature by combustion in a surrounding chamber, purging and vaporizing fluid from said chips, exhausting hot gases and exiting dried metal chips from said separator, conducting hot gaseous products of combustion from the combustion chamber to a continuous centrifuge, extracting extractable fluid from starting metal chips in the centrifuge, entraining the chips in the hot gaseous products of combustion introduced into the centrifuge, and conducting the gaseous products with entrained chips from the continuous centrifuge to the cyclone separator, thereby providing an essentially closed system. The combustion chamber may be a part of an afterburner furnace and hot gases entraining vaporized oil exhausted from the cyclone separator may be recycled and employed as fuel for the combustion chamber.  
           [0006]    U.S. Pat. No. 4,721,457 discloses a process for producing dried and cleaned metal chips by entraining metal chips in a gas, introducing the gas into a cyclone separator having a wall heated to fluid-vaporizing temperature by combustion effected in a surrounding chamber, purging fluid from said chips, exhausting hot gases and exiting dried metal chips form said separator, conducting hot gaseous products of combustion from the combustion chamber to a continuous centrifuge, extracting extractable fluid from starting metal chips, which may be previously uncleaned and/or unwashed, in the centrifuge, entraining the chips in the hot gaseous products of combustion introduced into the centrifuge, and conducting the gaseous products with entrained chips from the continuous centrifuge to the cyclone separator, thereby providing an essentially closed system. The combustion chamber may be a part of an afterburner furnace and hot gases entraining vaporized oil exhausted from the cyclone separator may be recycled and employed as fuel for the combustion chamber. Provision is made in the system for hot water and/or steam from either an external source of from a water jacket around the cyclone separator, preferably together with solvent and/or detergent, and a final chip drying step wherein the drying is effected using products of combustion which are enroute back to the continuous centrifuge.  
           [0007]    U.S. Pat. No. 4,872,907 discloses an apparatus and method for charging metal chips into a molten bath of the metal from which the chips are formed, comprising a compacting extruded and a delivery conduit which is resistant to the mass of molten metal and which is pivotable to dip into the molten metal bath when chips are being charged thereinto and out of contact with the bath when charging is to be discontinued, are disclosed. The chips are forced through the delivery conduit in the form of a compacted or densified mass preferably having a density between about 30 and 60 percent of the density of the solid metal and preferably between about 55 and 80 pounds per cubic foot. Feed is continued while the delivery conduit is in the molten metal bath and until it is removed therefrom to prevent entry of molten metal into the delivery conduit. The method is preferably conducted on a continuous basis and various sensors with appropriate wiring may be employed for safety and for making the method substantially automatic in operation.  
           [0008]    U.S. Pat. No. 5,203,910 discloses a method for the conveyance of molten metal from one place to another, in a high-temperature molten metal pool in a metal-melting furnace or out of said molten metal pool, employing an at least partially-inclined elongated conveying conduit and gas feed means for feeding inert gas into the lower end of the conveying conduit and thereby inducing a flow of molten metal in and through said conveying conduit, is disclosed, along with suitable apparatus for carrying out the said method wherein the parts or elements coming into contact with the high-temperature molten metal pool are of a suitable refractory material.  
           [0009]    U.S. Pat. No. 5,211,744 discloses a process for utilization of metal chips, especially scrap metal chips, particularly brass and aluminum, by introduction of the metal chips into a pool of molten metal of which they are formed or an alloy thereof. The process allows for minimization of fuel cost, heat loss, and minimal conversion of the metal at the surface of the molten metal pool to metal oxide, as well as an increase in the yield of utilizable metal from the remelting or recycling operation, by maintaining a non-oxidizing atmosphere at the surface of the molten metal pool and optionally utilizing vaporized residual impurities from chips being recycled such as oil, lacquer, or similar vaporizable impurity to assist in maintaining the non-oxidizing atmosphere. Elimination of impurity-removal steps previously required for preparation of the chips for recycling by introduction into such a molten metal pool is eliminated. Environmental pollution is also conveniently and simultaneously substantially reduced from vaporizable contaminants, fumes, and decomposition products of combustion thereof.  
           [0010]    U.S. Pat. No. 5,395,424 discloses a method for the conveyance of molten metal from one place to another, in a high-temperature molten metal pool in a metal-melting furnace or out of said molten metal pool employing at least a partially-inclined elongated conveying conduit and gas feed means for feeding inert gas into the lower end of the conveying conduit is employed. A flow of molten metal in and through said conveying conduit, is disclosed, along with suitable apparatus for carrying out the said method wherein the parts or elements coming into contact with the high-temperature molten metal pool are of a suitable refractory material. According to the present invention, an intermittent or pulsating inert gas feed is employed to produce essentially spherical or cylindrical bubbles within the conveying conduit, thereby resulting in greater efficiency and economy because of the possibility of reducing the quantity of inert gas employed to induce the flow of an identical amount of molten metal.  
           [0011]    U.S. Pat. No. 5,407,462 discloses a mass flow gravity feed furnace charger comprises a vertically-oriented elongated hollow conduit which is associated with an apertured heat-resistant charge-well cover adapted to lie essentially in contact with the upper surface of a molten metal pool in the charge well of a metal-melting furnace. Presized scrap metal charged into the conduit collects atop the surface of the molten metal pool, since the bottom opening of the conduit communicates with the charge-well cover aperture and permits the metal scrap to fall by gravity directly into the molten metal in the charge well. When the weight of the metal scrap column is sufficient to offset the resistance of the upper surface of the molten metal pool, the weight of the collected metal scrap gravitationally forces it into the molten metal mass it melts and is assimilated. Employment of the method and charge of the invention enables the controlled introduction of metal scrap by mass flow and gravity feed directly into and beneath the surface of the pool of molten metal and obviates numerous disadvantages and inconveniences of past practices.  
           [0012]    U.S. Pat. No. 5,468,280 discloses a method for the conveyance of molten metal from one place to another in a high-temperature molten metal pool in a metal-melting furnace or out of said molten metal pool. At least partially-inclined elongated conveying conduit and gas feed means for feeding inert gas into the lower end of the conveying conduit is employed. A flow of molten metal is thereby inducted in and through said conveying conduit, is disclosed, along with suitable apparatus for carrying out the said method wherein the parts or elements coming into contact with the high-temperature molten metal pool are of a suitable refractory material. The inert gas is fed into the conveying conduit at a supersonic velocity, thereby simultaneously effecting a degassing of the molten metal while it is being conveyed.  
           [0013]    U.S. Pat. No. 5,735,935 discloses an inert gas bubble-actuated molten metal pump which is located in a metal-melting furnace to effect circulation of molten metal throughout the furnace. The inert gas employed to actuate the molten metal pump is captured beneath a heat-resistant and flame-resistant cover located above the exit port of the pump and over a substantial portion of the molten metal to thereby to prevent splashing, spattering and disruption of a thin protective layer or skin of oxidized metal at the surface of the molten metal as well as to provide a non-oxidizing atmosphere at the surface of the molten metal beneath said cover. In this manner the inert gas is employed efficiently and economically.  
           [0014]    U.S. Pat. No. 5,853,454 discloses a mass flow gravity feed furnace charger apparatus includes a charge-well cover having an aperture and an essentially vertical conduit for forming a substantially vertically-oriented column of metal chips or scrap within and above the aperture, and structure for bringing both the cover and conduit into position above a charge-well. The conduit is rapidly movable up and down to force the metal chips or scrap into molten metal in the charge-well even when the dross level at the surface of the molten metal is considerable, so that the apparatus and corresponding methods permit charging when gravity feed alone is not sufficient or sufficiently rapid. In a preferred embodiment, the conduit has an interior surface provided with gripping means to assist with the downward movement of metal chips or scrap into the molten metal in the charge well when the up and down motion of the conduit is in effect.  
           [0015]    U.S. Pat. No. 5,919,283 discloses an inert gas bubble-actuated molten metal pump is located between one section of a metal-melting furnace and a second section to pump molten metal form the one section, wherein the molten metal is at a higher temperature, into the second section, wherein the molten metal is at a lower temperature, and its effluent is directed into contact with metal chips being charged into the second section, thereby assisting in the more rapid melting of the chips into the molten metal mass in the second section. The inert gas employed to acturate the molten metal pump is captured beneath a heat-resistant and flame-resistant cover located above the exit port of the pump and over a substantial portion of the molten metal mass in the second section, thereby providing a non-oxidizing atmosphere at the surface of the molten metal mass or pool beneath said cover. In this manner the inert gas is employed not only to actuate the inert gas bubble-actuated molten metal pump, but also to assist in the rapid melting of metal chips being charged, as well as to provide a non-oxidizing atmosphere at the surface of the molten metal.  
           [0016]    U.S. Pat. No. 5,984,999 discloses an arrangement in which the vortex well of a metal melting furnace is provided with an internal cavity having a circular cross section when viewed from the top, preferably a cavity of cylindrical or conical configuration, and with a peripheral exit port located tangentially with respect to said cavity at a lower level thereof for exit of molten metal into the main chamber of the furnace. An inert gas bubble-actuated molten metal pump brings molten metal from a hotter section of the furnace, advantageously directly form the main chamber, and has its exit port located tangentially to the periphery of the cavity at an upper level thereof, thereby creating vortical flow of molten metal therein and for circulation of hotter molten metal throughout the furnace. A head of molten metal can be created in the vortex well, which advantageously has an exit port of restricted internal cross-sectional area, to assist with attainment of these objective. A heat and flame-resistant cover may be located above the cavity and advantageously has an aperture therein for the loading of metal chips or scrap thereinto. A gravity-feed chip charger may surmount the aperture for the discharge of new metal chips or scrap into the cavity through the said aperture.  
           [0017]    U.S. Pat. No. 6,068,812 discloses an inert gas bubble-actuated molten metal pump, for the movement of molten metal in a molten-metal bath, which obviates the necessity of a heatproof and flamepoorf cover to counteract splashing and spattering at the surface of the molten metal bath above the pump, comprising an inert gas diffusion means at an upper end thereof, the diffusion means having an upper surface containing a multiplicity of small upwardly-opening apertures for the breaking up of large bubbles and the diffusion of small bubbles of inert gas upwardly therethrough. The pump includes a refractory block which comprises a conveying conduit which is preferably elongated in width and a spreader cavity in communication with both a passageway in the block for providing a source of inert gas and a lower end of the conveying conduit.  
           [0018]    My above referenced patents are incorporated herein by reference.  
           [0019]    The purpose for creating a vortex in the vortex well is to rapidly submerge the small particles of metal whose mass would otherwise prevent the particles from penetrating the surface tension of the molten metal bath, thus causing a substantial increase in the percentage of metal loss due to oxidation. It has, however, has been determined that further steps must be taken to reduce oxidation, particularly when relatively more expensive metals such as aluminum are being used.  
         SUMMARY OF THE INVENTION  
         [0020]    It is an object of the present invention to provide a means for further reducing metal losses due to oxidation in the vortex molten bath.  
           [0021]    It is another object of the present invention to provide a way of integrating the functions of circulating molten metal and submerging metal chips in molten metal vortex to allow for rapid recovery of any temperature drop which may result from the introduction of the cold scrap.  
           [0022]    It is still another object of the present invention to provide a means for efficiently burning off volatile hydrocarbons which may be present with metal chips that are being melted.  
           [0023]    These and other objects are attained by the present invention which is a metal melting closed furnace which includes a main chamber, a circulation well connected to the main chamber by a communications passageway and a vortex well having an exit outlet for molten metal into the main chamber. A cover or other suitable containment means is emplaced above the vortex well. An inert gas bubble activated molten metal pump is provided in which there is an entry port in the circulation well and exit port tangentially arranged with respect to the periphery of the cavity. This exit port will typically be at or near the top of the vortex well. In order to reduce oxidation, inert gas bubbles are captured from this molten metal pump and are transported to an inert gas atmosphere or blanket above the molten metal vortex so that this inert gas atmosphere is continuously or intermittently replenished.  
           [0024]    Also encompassed by the present invention is a process for melting metal in a furnace in which molten metal is heated in a main chamber and then circulated to a circulation well. The molten metal is then removed from the circulation well by an inert gas bubble actuated pump to the vortex well. An inert gas atmosphere is formed below the cover and is continuously or intermittently replenished by gas from the bubbles in the pump.  Also encompassed by the present invention is a metal-melting furnace which includes a main chamber and a circulation well connected to the main chamber by a communication passageway. There is also a vortex well having periphery, a top and an exit outlet for recovering molten metal therefrom, and a cover is emplaced over the vortex well. The furnace also includes an inert gas bubble actuated molten metal pump having an entry port in the circulation well and an exit port tangentially arranged with respect to the periphery of said vortex well at or near the top of the vortex well, wherein the exit port is positioned at a vertical position which is higher than the entry port. There is also an inert gas atmosphere positioned in the vortex well beneath the cover.    
           [0025]    Also encompassed by the present invention is a metal-melting furnace which includes a main chamber and a circulation well connected to the main chamber by a communication passageway. There is also a vortex well having a periphery, a top and bottom exit outlet for recovering molten metal therefrom, and a cover is emplaced over the vortex well. The furnace also includes an inert gas bubble actuated molten metal pump having an entry port in the circulation well and an exit port tangentially arranged with respect to the periphery of said vortex well at or near the top of the vortex well. There is also an inert gas atmosphere positioned in the vortex well beneath the cover.  
           [0026]    Also encompassed by the present invention is a metal melting furnace which includes a main chamber and a circulation well containing molten metal having a surface level connected to the main chamber by a communication passageway. There is a vortex well having a periphery, a top and an exit outlet for recovering molten metal therefrom, and a cover is emplaced over the vortex well. The furnace also includes an includes a sensor for measuring the surface level of the molten metal in the circulation well and a means for vertically positioning the cover to a position selected based on the measured surface level of the molten metal.  
           [0027]    Also encompassed by the present invention is a metal-melting furnace which includes a main chamber and a circulation well connected to the main chamber by a communication passageway. There is also a well block having, a vortex well, said vortex well having a periphery, top and an exit outlet for recovering molten metal therefrom. A cover is emplaced over the vortex well, wherein said cover has a periphery positioned in inward spaced relation to the well block to form a peripheral gas release space between said cover and the well block. The furnace also includes an inert gas bubble actuated molten metal pump having an entry port in the circulation well and an exit port tangentially arranged with respect to the periphery of said vortex well at or near the top of the vortex well. An inert gas and volatile hydrocarbon gas atmosphere is positioned in the charge well beneath the cover, and this atmosphere is releasable through said peripheral gas release space.  
           [0028]    Also encompassed by the present invention is a metal-melting furnace which includes a main chamber and a circulation well connected to the main chamber by a communication passageway. There is also a vortex well containing a molten metal vortex and having a periphery, a top and an exit outlet for recovering molten metal therefrom and a cover is emplaced over the vortex well adjacent the surface of the molten metal vortex. The furnace also includes an inert gas bubble actuated molten metal pump having an entry port in the circulation well and an exit port tangentially arranged with respect to the periphery of said vortex well at or near the top of the vortex well. An inert gas atmosphere is also positioned in the vortex well beneath the cover.  
           [0029]    Also encompassed by the present invention is a metal-melting furnace which includes a main chamber and a circulation well connected to the main chamber by a communication passageway. There is also a vortex well having a periphery, a top and an exit outlet for recovering molten metal therefrom and a cover emplaced over the vortex well. A feed tube extends through said cover to enable metal chips to be tangentially added to the vortex well adjacent the periphery of said vortex well. The furnace also includes an inert gas bubble actuated molten metal pump having an entry port in the circulation well and an exit port tangentially arranged with respect to the periphery of said vortex well at or near the top of the vortex well. An inert gas atmosphere is also positioned in the vortex well beneath the cover.  
           [0030]    Also encompassed by the present invention is a metal-melting furnace which includes a main chamber and a circulation well connected to the main chamber by a communication passageway. The furnace also includes a vortex well having a periphery, a top and an exit outlet for recovering molten metal therefrom and said vortex well is positioned in a vortex well block. A cover is also emplaced over the vortex well. There is also an inert gas bubble actuated molten metal pump having an entry port in the circulation well and an exit port tangentially arranged with respect to the periphery of said vortex well at or near the top of the vortex well. An inert gas atmosphere positioned in the vortex well beneath the cover. An end block is also positioned in adjoining relation to the vortex well block. These blocks are connected by a projection extruding from one block which engages a recess in the other block. The circulation well is contained in said adjoining blocks.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]    The present invention is further described by means of the accompanying drawing in which:  
         [0032]    [0032]FIG. 1 is a vertical cross-sectional view of a molten metal pump and furnace for use therewith which comprises a preferred embodiment of the present invention;  
         [0033]    [0033]FIG. 2 is a cut away perspective view of the main molten metal chamber, circulation wall, vortex well and adjacent chamber of the molten metal pump and furnace in FIG. 1;  
         [0034]    [0034]FIG. 3 is a cross-sectional through  3 - 3  in FIG. 2;  
         [0035]    [0035]FIG. 4 is a partial end view of the molten metal pump and furnace shown in FIG. 1 from  4 - 4 ;  
         [0036]    [0036]FIG. 5 is a cross-sectional view through  5 - 5  in FIG. 1;  
         [0037]    [0037]FIG. 6 is an end view from  6 - 6  of the molten metal pump and furnace shown in FIG. 1;  
         [0038]    [0038]FIG. 7 is a detailed view of area  7  in FIG. 1;  
         [0039]    [0039]FIG. 8 is a cross sectional view through  8 - 8  in FIG. 1;  
         [0040]    [0040]FIG. 9 is a partial top view of the well block and end block from  9 - 9  in FIG. 1;  
         [0041]    [0041]FIG. 10 is a vertical cross-sectional view similar to FIG. 1 in which the feed tube and vortex well cover are in their elevated positions;  
         [0042]    [0042]FIG. 11 is a detailed view similar to FIG. 7 in which the feed tube and vortex well cover are in intermediate elevated position still covering the vortex well; and  
         [0043]    [0043]FIG. 12 is a top plan view of the vortex well lock and part of the end block from  12 - 12  in FIG. 11 in which an alternate vortex well cover is shown. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0044]    Referring to FIGS.  1 - 9 , the furnace is shown generally at  10  has a bottom wall  12 , side walls  14  and  16 , front wall  18  and a rear wall  19 . The furnace also has an intermediate transverse wall  20  which defines along with the other wall a main chamber  22 . As is conventional fossil fuel burners (not shown) are used to maintain a molten metal bath  24  in this main chamber. The main chamber  22  also has a cover shown in fragment at numeral  26 . Adjacent the main chamber  22  is a circulation chamber  28  also having a molten metal bath  30  which is connected to the main chamber 22  by means of communicating passageway  32 . The molten metal may be aluminum, magnesium, zinc, copper, brass or steel.  
         [0045]    Adjacent the circulation chamber  28  there is a molten metal pump shown generally at  34  which includes an end block  36 . Adjacent the end block  36  there is well block  38 . Preferably the well block  38  is a separate and replaceable block of refractory material. It would alternately be possible to integrate the end block  36  and well block  38  into a single unit. In the end block  36  there is end block projection  40  which engages recess  42  on the well block  38 . Between the end block  36  and well block  38  there is also a vertical space  44 . In the end block  36  there is also a vertical passageway  46  which with a lower opening  48  an medial outlet  50 . There is also an inert gas line  52  which extends from a tank  54  containing nitrogen, argon or other inert gas, to controls  56  and then to inert gas outlet  58  into passageway  46 . Adjacent the medial outlet  50  of the vertical passageway  46  there are seals  60  and  62  at which point the vertical passageway  46  connects to horizontal passageway  64  in the well block  38 . This horizontal passageway  64  has an opening  66  and an outlet  68  adjacent a plate  70  with a plurality of apertures as at aperture  72 . As is conventional in a molten metal pump as in molten metal pump  34  there are a plurality of inert gas bubbles  74 ,  76 , and  78  in the vertical passageway  46  and horizontal passageway  64  which rise to move molten metal masses as at  80  and  82  from the circulation chamber  38  to the vortex well shown generally at  84 . Above the plate  70  there is an inert gas collection recess  86  in the well block  38 . The vortex well  84  has an upper region  88 , medial region  90  and a lower region  92  with a surrounding liner  84 . At the bottom of the lower region  92  there is a lower outlet  96  which communicates with a bottom recess  98  in the well block  38 . A horizontal passageway  100  next to a intermediate well  102 . In this intermediate well  102  there is another molten metal bath  104  which re-circulates back to the main chamber  22  by means of communicating passageway  106 . Above the vortex well  84  there is a refractory cover  108 . Other suitable vortex well containment means such as an upward extension of the vortex well shown generally as numeral  109  in FIG. 7 may be substituted for the cover  108 . The cover  108  will be equipped with a sensor  110  which overlies a molten metal vortex  112  in the vortex well  84 . The sensor  110  senses the surface level of the molten metal vortex  112  to enable the cover  108  to be raised or lowered as is described hereafter. Between the cover  108  and the molten metal vortex  112  there is an inert gas atmosphere or blanket  114  which is continuously or intermittently replenished with inert gas from inert gas bubbles in the pump  34  which enter recess  86  through apertures as at aperture  72  in plate  70 . Between the cover  108  and the well block  38  there is a peripheral space  116  which allows for the formation of a combustion zone  118  for allowing oils, paints, lacquers as well as other volatile hydrocarbons to exit from below the cover and be burned off. It will be appreciated that this peripheral space  116  will also allow the escape of inert gas from the inert gas atmosphere or blanket  114  as additional inert gases are added to this space. The well cover  108  will have sufficient space around its periphery to allow oil, paints, lacquer or nitrogen, as well as any other volatile hydrocarbons, to exit from below the cover, which has been carried into the molten metal stream on the scrap charge material. This heat resistant cover  108  would be adjustable in height, but would normally provide several inches of clearance above the surface of the molten metal bath for the containment of the replenishing supply of inert gas. Above the combustion zone  118  there is a smoke collection hood  120  with air intakes  124  and  126  having respectively closure doors  128  and  130 . From the smoke collection hood  120  there is a line  132  to a stack or particle collection equipment (not shown). Extending downwardly through the smoke collection hood  102  there is a scrap feed tube  134  in which scrap as in metal chips  136  are feed into the molten metal vortex  112  in the vortex well  84 . It will be appreciated that metal scrap may be substituted for metal chips and, for the purposes of this disclosure the term “metal chips” should be understood to include both metal chips and metal scrap. The metal chips  136  are preferably fed tangentially into the molten metal vortex adjacent the periphery of the vortex well  84 . The feed tube  134  is attached to the cover  108  by means of a flange  138 . At its upper end feed tube  134  receives metal chips from a hopper  140  which is in turn fed by a screw Conveyor  142  which receives metal chips from a feed opening  144 .  
         [0046]    Referring to FIG. 10, it will be seen that the feed tube  134  and cover  108  may be withdrawn upwardly from the vortex well  84  by well known conventional means.  
         [0047]    Referring to FIG. 11, it will be seen that the feed tube  134  may also be adjusted in height so that the cover  108  at the top of the vortex well  84 . The height of the inert gas blanket  114  is thereby may be adjusted. The vertical position of the cover  108  is preferably selected with reference to the surface level of the molten metal in the vortex well  84  which is measured by sensor  110 .  
         [0048]    Referring to FIG. 12, an alternate embodiment of the cover is shown. In this embodiment a well block  146  is shown as well as the end block  148  in fragment. A vertical space  150  is interposed between the well block  146  and end block  148 . An alternate cover  152  is positioned on the top of the well block  146  by means of radial peripheral supports  154 ,  156 ,  158  and  160 . Between the cover  158  and the well block  148  there are peripheral spaces  162 ,  164 ,  166  and  168  and positioned above these peripheral spaces there are respectively combustion zones  170 ,  172 ,  174  and  176 . A feed tube  180  connected to the cover  152  by means of a bracket  182  allows metal chips to be fed into the molten metal vortex  184 .  
       Mode of Operation  
       [0049]    In the operation of the molten metal pump and furnace of the present invention metal chips are fed into the feed opening  144  of conveyor  132  which transports these metal chips to hopper  140  from which they descend into the feed tube  134  to vortex well  84  where they are added to the molten metal vortex  112 . At the same time nitrogen or other inert gas was drawn from tank  54  through line  52  and controls  56  to form bubbles as at bubble  48  in the vertical passage way  46  of molten metal pump  34 . These inert air bubbles move molten metal masses as at mass  64  from molten metal bath  30  in the circulation chamber  20  to molten metal vortex  112  in vortex well  84 . When these bubbles as in bubble  74  enter the horizontal passageway  64  of the molten metal pump  34  they pass through apetures as at apeture  72  in plate  70  to enter recess  86  and thereafter enter vortex well  84  between the molten metal vortex  112  and the cover  108  to form the inert gas atmosphere or blanket  114 . Alternatively the inert gas blanket may be contained by upwardly extended walls of the vortex well  84 . It will thus be understood that such containment means may be either a cover as at cover  108  or by extended walls of the vortex well  84 . This inert gas blanket  114  reduces the formation of oxidation on the metal chips entering the molten metal vortex  112 . Oil, paints, lacquers and other volatile hydrocarbons which may be present within the metal chips are volitized and passed through the peripheral space  116  between the cover  108  and the well block  38  to be burned in the combustion zone  176 . The metal chips flow along with the rest of the molten metal vortex  116  in a swirling downward path to outlet  96  and bottom recess  90  where the direction of the molten metal is changed to a lateral flow path through horizontal passageway  100  into intermediate well  102 . From intermediate well  102  molten metal in molten metal bath  104  goes through passageway  106  to main chamber  22 . After heating in main chamber  22  molten metal passes through passageway  32  into circulation chamber  38 . From the molten metal bath  30  in circulation chamber  28  the molten metal is again pumped through molten metal pump  34  back to vortex well  84  where additional metal chips are again added under inert gas blanket  114  in the same way. It will be understood that it would alternately be possible to remove molten metal from the passageway  32  adjacent circulation chamber  28  to the vortex well. For the purposes of this disclosure, the removal of molten metal from the circulation chamber to the vortex well will be considered to also include the embodiment of removing molten metal from the adjacent passageway.  
         [0050]    It will be appreciated that a molten metal pump and furnace for use therewith and a method for its operation has been described in which oxidation of metal chips entering molten metal vortex is substantally reduced.  
         [0051]    It will also be appreciated that the present invention allows for the combination of the functions of circulating molten metal in a fossil fuel reverberatory furnace and submerging metal chips in an open side well chamber to cause the melted feed stock to be rapidly circulated back into the main chamber of the furnace. Any resulting loss in temperature due to the introduction of the cold scrap, can quickly be recovered in the presence of the combustion burners located in the enclosed main chamber of the furnace.  
         [0052]    It will also be appreciated that the present invention also lends itself to melting materials such as undelaquered UBC (used beverage cans) with substantially improved melt yield, without requiring the prior step of delaquering the UBC in advance of this melting process.  
         [0053]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.  
         [0054]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.