Abstract:
A crust breaker and ore feeder device for electrolytic aluminum smelting employs an in-line three-position pneumatic cylinder capable of moving the plunger shaft between a raised position and a fully lowered position. A dose meter in the form of a cylindrical member rests a small distance above the valve seat of the crust breaker. In the raised position the dose meter fits within the dosing cup and receives the dose of alumina. In the lowered position of the crust breaker, the dose meter slows down the flow of alumina into the electrolytic liquid, with the alumina flowing out through cutouts formed in the lower rim of the dose meter.

Description:
This patent application claims priority under 35 U.S.C. 119(e) of provisional patent application Ser. No. 61/917,118, filed Dec. 17, 2013. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention is directed to a device used in the refining of aluminum, i.e., smelting, in which a pneumatically driven hammer is employed for punching through the crust that develops on top of the molten refined aluminum-electrolyte, and there is an alumina dispenser cup or chamber that fills with alumina (typically comminuted into a powder form) and then the cup dispenses the alumina when the hammer is driven downward. A suitable crust punch and alumina dispenser device is described in our prior U.S. Pat. No. 7,892,319, granted Feb. 22, 2011. 
     In this improvement, a generally cylindrical-shaped dose meter or alumina flow limiter is positioned onto the shaft of the crust breaker within the space of the dispenser cup and just above the valve seat. The alumina dust fills the cup when the crust breaker shaft is raised, and then when the crust breaker descends the valve seat pulls away from the lower rim of the cup and the alumina then pours out onto the molten material in the aluminum smelting pot. The objective of the dose meter is to slow down the flow of the alumina powder so that it is not dumped in all at once, but flows out over a period of several seconds. To that end, the cylinder-shaped dose meter is spaced a short distance above the top surface of the valve seat and there are also a number of cutouts in the lower rim of the dose meter. This ensures that the entire dose will flow out, and the space between the dose meter and the valve seat flows the material out so that the alumina material does not clog behind the dose meter. The dose meter ensures a more regulated rate of flow of the alumina powder. 
     The flow-regulating or flow-limiting device can take the form of a generally cylindrical sleeve that fits inside the cup or dose holder and may optionally have a small stand-off between the bottom edge and the valve cone, and also may have notches or cutouts in the lower edge, so that when the cup is opened, the aluminum ore flows in a slower stream instead of being dumped in suddenly into the molten electrolyte in the aluminum smelting pot. Favorably, the dose meter is to be used with a combination crust breaking and alumina feeding device, capable of both dosing and crust breaking, or dosing alone or crust breaking alone. Embodiments of the dose meter can be in the form of two identical halves that bolt together on the chisel shaft above the valve seat, with notches cut out of the bottom edge, and possibly with feet or standoffs to keep the lower edge of the dose meter a small distance above the valve seat. Other embodiments may be formed of three, four, or more components that bolt or fasten together about the chisel shaft. 
     The combination crust breaker and ore feeder or dispenser can be of the type described in our earlier U.S. Pat. No. 7,892,319, which is incorporated herein by reference, or for example in U.S. patents to Kissane, U.S. Pat. No. 5,423,968 or U.S. Pat. No. 5,324,408. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIGS. 1 and 2  are sectional drawing views of a crust breaker and ore feeder device according to the prior art, with  FIG. 1  showing the crust breaker and ore feeder device in the raised position, in which the cup or dispenser fills with alumina powder, and with  FIG. 2  showing the device in the lowered or descended position, in which the crust breaker hammer is driven downward and the valve seat portion of the cup is opened to allow the alumina powder to fall down into the electrolyte in the smelting pot. 
         FIGS. 3 and 4  are perspective views of the dose meter according to one embodiment of the invention. 
         FIG. 5  is a perspective view of the two halves of the dose meter, showing the outer surface of the outer half cylinder walls. 
         FIG. 6  is another perspective view of the two halves thereof, showing the inner surfaces of the inner half rings, and also illustrating the connecting flanges, bolt holes and spacer finger. 
         FIG. 7  is an inverted perspective view thereof, showing the notches or cutouts in the bottom edge thereof. 
         FIG. 8  it a bottom plan thereof. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the Drawing, and initially to  FIGS. 1 and 2 , a typical ore feeder and crust breaker arrangement  10  is shown in  FIG. 1 , here in its raised position. The feeder portion thereof in its lowered or open position (for dispensing ore) is shown in  FIG. 2 . The feeder and crust breaker assembly  10  is positioned on the top wall or cover of an aluminum smelting pot, not shown, above the molten electrolyte. The assembly  10  has an elongated cylindrical housing  12 , with a mounting flange  14  at its top. The housing  12  fits within a round opening provided in the top cover of the pot. There is a tapered lower end  16  that is intended to confine the distribution of the alumina so that it is dispensed near the opening that is created in the top crust layer. 
     A plunger shaft  20  extends along the vertical axis of the assembly  10  and is adapted for vertical motion along that axis. There is a chisel or hammer  22  mounted at the lower end of the shaft  20 , and this chisel is adapted to break through the crust on the electrolyte upper surface to create an opening to admit the alumina powder into the molten liquid. In the electrolytic refining process, a surface coating of contaminates can develop on the chisel  22 , and its presence within the electrolyte can sometime produce adverse electrical effects within the molten electrolyte. 
     A dose holder or cup  24  is located above the plunger chisel  22  within the housing. The dose holder  24  is typically of a cylindrical shape with an open upper end to receive the alumina powder and an open lower end for dispensing the powder. There is a cylindrical gate  26  that moves upward and downward, relative to the cup  24 , to admit the ore powder into the cup and to close off the cup, respectively. A supply of alumina powder is contained within a hopper  28 , and this alumina proceeds through apertures or ports in the housing  12  to the dose holder  24 . A valve seat  32  is positioned on the shaft  20  at the lower end of the cup or dose holder  24 . This valve seat  32  moves down when the shaft descends to open the dispenser cup and allow the alumina powder to fall from the cup and out the lower end of the housing. When the shaft ascends to its raised position, the valve seat  32  closes off the cup  24 , and the gate  26  opens to admit the next measured dose of alumina powder. The valve seat  32  is slidable on the shaft  20 , and a sleeve  34  on the shaft supports the valve seat  32  from below, so that the seat  32  moves downward a small distance when the shaft descends, and returns back to the closed position when the shaft  20  is fully raised. 
     An air cylinder  36  is disposed within the upper part of the housing  12 . This cylinder  36  has a piston and rod, not shown, with the rod being connected to an upper end of the shaft  20 . The cylinder may be a two-position cylinder or three-position cylinder, with upper and lower air ports and with air supply lines for driving the shaft  20  and chisel  22  downwards, i.e. to a fully extended position, when air is supplied, and for raising the shaft and chisel back to their elevated position. There is a pneumatic control (not shown) for controlling the application of compressed air to the respective supply lines. Typically, the pneumatic control is located at some distance from the feeder and crust breaker assembly, which necessitates having numerous air lines extending above the pot cover to reach each feeder and crust breaker assembly for that pot. 
     A generally cylindrical dose meter  40  is positioned over the chisel shaft  20  and may optionally rest on a cone-shaped inner portion  42  of the valve seat. This dose meter  40  is adapted to moderate the flow of alumina powder when the valve seat  32  opens, so that there is an extended moderate flow of the ore instead of a sudden drop of the entire dose onto the electrolyte. 
     This dose meter  40  is positioned within the cup  24  when the chisel and valve seat  32  are in the raised position ( FIG. 1 ), and descends with the valve seat  32  when the shaft and valve seat moves to the open or lowered position as shown in  FIG. 2 . 
     The construction of the dose meter  40  of this embodiment is illustrated in  FIGS. 3 to 8 . 
     Dose meter  40  is formed of two identical halves  40 A and  40 B as shown in  FIGS. 3, 4, 5 and 6 , which fit together around the shaft  20 . Each half is formed of steel, with an outer semi-cylinder  42  of a nominal outside diameter of 4¾ inches, an inner coaxial half-ring  44  of a nominal inside diameter of 2⅜ inches. Radial connecting flanges  46  join the ends of the outer semi-cylinder  42  to the ends of the inner half-ring  44 . In this embodiment, the height of this dose meter  40  is about 2½ inches. The notches  54 , discussed below, are about one inch wide and one inch in height. The notches can be V-shaped or U-shaped, or can be of a multitude of other patterns, e.g., holes, rectangular notches, etc. 
     The connecting flanges  46  have mating bolt holes  48  to receive a threaded connector (not shown) with one of the flanges also having an associated female-threaded nut  50  welded at the bolt hole  48 . Access openings  56  are provided in the semi-cylinder for a screwdriver or other tool to tightening threaded fasteners in the bolt holes  48 . These may be omitted in some embodiments if other fastening means are employed. 
     The outer semi-cylinders  42  each have a lower edge  52  and there are notches or cutouts  54  that extend up from the edge  52 . The notches or cutouts  54  are somewhat V-shaped in this embodiment. In this example, one of the connecting flanges  46  of each half  40 A,  40 B has a finger or stand-off  58  that projects downward to rest upon the cone-shaped portion  42  of the valve seat  32 . This creates a small gap or space between the lower edges  52  of the dose meter  40  and the valve seat  32  so that the alumina powder does not accumulate behind the semi-cylinder. However, the dose meter can be positioned on the shaft  20  offset from the dispersion cylinder  42  to allow for complete emptying of the alumina. This offset can be achieved via an offset due to the finger or stand-off  58  or via being attached at a set position above the dispersion cylinder. There may be a wide difference in the size and shape of the dispersement cone from one manufacturer to another. 
     When the shaft  20  and valve seat  32  of the dose holder or cup  24  is in the raised ( FIG. 1 ) position, the cup  24  fills in the normal fashion with alumina powder from the hopper  28 . Then, when the cylinder  36  is actuated to move the shaft  20  downward, and the valve seat descends to the open position ( FIG. 2 ), the alumina dust flows out through the cutouts  54  and through the small gap between the lower edge  52  of the dose meter and the upper surface of the valve seat  32 . This provides for a gentler, moderated flow of ore into the electrolyte, avoiding some of the problems that occur from the rapid dumping of ore that occurs without dose regulation. 
     In this embodiment, the dose meter is formed of two identical halves  40 A and  40 B. In other possible embodiments the dose meter could be formed, e.g., from three 120-degree segments or four 90-degree segments. The segments do not necessarily need to be identical. In still other possible embodiments the cutouts or notches  54  may be omitted with all the alumina escaping beneath the lower edge  52 . 
     While this invention has been described in respect to one preferred embodiment, the invention is not limited only to that embodiment. Rather the scope of the invention is to be measured in terms of the appended Claims.