Abstract:
An airstream solid sorting technology easily and efficiently sorts electric wire and other slender objects from other unslender objects in crushed bulk wastes. A mixture of slender and unslender objects is supplied into an airstream sorting vessel, in which a turbulent stream of gas supplied from below through a meshed screen tilted in its bottom agitates the mixture. Slender objects stalling and falling longitudinally in the direction in which gravity works pass through the meshed screen, thus falling into a slender objects collecting vessel placed below the meshed screen. Unslender objects sliding down along the tilted meshed screen are thus separated.

Description:
FIELD OF THE INVENTION 
     Valuables recovered for recycling from crushed pieces of such bulk wastes as discarded household electrical appliances and automobiles must be sorted and classified according to types of their materials. Particularly, slender pieces of copper cut from electromagnet coils and covered electric wire have relatively high values. However, there have been no appropriate technologies for sorting such slender objects from unslender ones. 
     This invention relates to a method and an apparatus for sorting solids by airstream that can separate slender pieces of copper of high added-values from unslender pieces by noting the difference in shape. 
     DESCRIPTION OF THE PRIOR ART 
     Discarded household electrical appliances and automobiles contain various kinds of motors, coils, electric wires, etc. For recycling, such pieces must be disassembled, crushed and sorted out by types of materials. However, conventional sorting technologies using wind force, jigs, tables, fluidized beds, cyclones, etc. cannot sort out crushed pieces of coils and covered wire with high efficiency and accuracy. On the other hand, conventional wet classifying technologies require some post treatments including drying. Therefore, development of an efficient dry classifying technology requiring no post-treatment has been awaited. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide a method and apparatus for sorting solids by airstream that permits easy and efficient sorting of slender objects consisting essentially of copper in a dry state from crushed pieces of such bulk wastes as discarded household electrical appliances and automobiles. 
     Another object of this invention is to provide a method and apparatus for sorting slender objects by airstream by taking advantage of the tendency of slender objects to fall vertically or longitudinally, with the length thereof parallel to the direction in which works, when a mixture of needle-shaped and unslender objects is exposed to an up-coming airstream in an airstream sorting vessel. 
     Still another object of this invention is to provide a method and apparatus for efficiently sorting slender objects from unslender ones by causing them to float and fall in an airstream whose flow speed is intermittently varied. 
     Yet another object of this invention is to provide a method and apparatus for further sorting the separated unslender objects into less floatable objects and more floatable ones by airstream in a secondary unslender object sorting vessel provided next to the primary sorting vessel. 
     To achieve the above objects, an airstream sorting method according to this invention essentially comprises supplying a mixture of slender and unslender objects into an airstream sorting vessel flaring upward, into which turbulent airstream is supplied from below through a meshed screen tilted in the bottom of the vessel. When the upcoming airstream agitates the mixture in the vessel, slender objects stalling longitudinally fall through the meshed screen into a collecting vessel placed therebelow, whereas unslender objects flow down along the tilted meshed screen to the outside. 
     An airstream sorting apparatus according to this invention comprises an upwardly flaring airstream sorting vessel into which a mixture of slender and unslender objects to be sorted is supplied, a meshed screen tilted in the bottom of the sorting vessel whose meshes are large enough to pass the slender objects falling longitudinally but not large enough to pass any other larger objects, a slender objects collecting vessel placed below the meshed screen and having an opening to supply an airstream to agitate the mixture of slender and unslender objects, and an outlet for the unslender objects opened at the lower end of the tilted meshed screen. 
     An unslender objects sorting apparatus may be provided downstream of the airstream sorting vessel and needle-shaped objects collecting vessel described above to re-sort the separated unslender objects into more floatable and less floatable objects by using an airstream. 
     In the airstream sorting apparatus described above, a required amount of air is supplied through the air-supply port from below the meshed screen into the sorting vessel. The upcoming turbulent airstream floats and agitates the mixture of need-shaped and unslender objects. Even the readily floatable objects do not scatter away during moving as the upwardly flaring vessel rapidly decreases the flow speed of the ascending airstream. 
     The mixture float and fall repeatedly in the airstream. In the stalling and falling stage, slender objects turn upright in the direction in which gravity acts, thus loosing their buoyancy and falling through the meshed screen disposed in the bottom. Then, the mixture is sorted into the slender objects passed through the meshed screen and the unslender objects that remain thereon. 
     The sorting method and apparatus of this invention thus easily and efficiently sort slender objects from crushed wastes of such bulk wastes as used household electrical appliances and automobiles in a dry state by taking advantages of the difference in shape. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional side elevation of an airstream sorting apparatus according to this invention. 
     FIG. 2 is a cross-sectional top view of the same airstream sorting apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now a preferred embodiment of this invention will be described in detail by reference to the accompanying drawings. 
     An airstream solid sorting apparatus according to this invention shown in FIGS. 1 and 2 is used for sorting slender objects from unslender objects resulting from the crushing of coils and electric wires in coils and other parts of such wastes as used household electric appliances and automobiles that are disassembled, crushed and sorted for recycling. The airstream solid sorting apparatus comprises an upwardly flaring sorting vessel 1 into which a mixture of slender and unslender objects to be sorted is supplied, a meshed screen 2 tilted in the bottom of the vessel 1, and a slender objects collecting vessel 3 placed below the meshed screen 2. 
     The airstream sorting vessel 1 having an open top end and an upwardly flaring body decreases the flow speed of an airstream supplied from below the collecting vessel 3 and meshed screen 2 and ascending through the vessel 1. The meshed screen 2 tilted in the bottom of the sorting vessel 1 may be made of a perforated plate or a framed grid of wire netting. The mesh size is large enough to pass the slender objects falling longitudinally in the direction in which gravity works and not large enough to pass other larger objects. 
     A vibrator 4 to vibrate the meshed screen 2 to facilitate the motion of the unslender objects may be connected to the airstream sorting vessel 1 or meshed screen 2. 
     The slender objects collecting vessel 3 placed below the meshed screen 2 hold the slender objects sorted through the meshed screen 2, whereas an airstream is supplied through the collecting vessel 3 and meshed screen 2 into the sorting vessel 1. A recovery cylinder 6 having a space to temporarily hold the slender objects formed between two movable dampers 7 and 8 is connected to the lower end of the collecting vessel 3 through a flanged joint 5. A slender objects discharge cylinder 10 is connected to the recovery cylinder 6 through a flanged joint 9. 
     The airstream sorting vessel 1 and slender objects collecting vessel 3 may be made of carbon steel, stainless steel, aluminum or other metal, plastics, or mixtures thereof. 
     The slender objects collecting vessel 3 has a primary gas inlet 15 through which a primary gas supplied through a primary gas supply pipe 11, a gas supply cylinder 12 and a branch cylinder 13 having a damper 14 is introduced. The damper 14 controls the volume of the primary gas supplied through the branch cylinder 13. The slender objects collecting vessel 3 also has an inlet 18 at which a secondary gas supply pipe 16 (see FIG. 2) having a damper 17 opens. The supply pipe 16 intermittently supplies a secondary gas from a separately prepared blower through the inlet 18 by intermittently opening and closing the damper 17 be means of a drive unit 17a. The intermittently supplied gas forces the objects to be sorted to float and fall repeatedly. 
     An unslender objects outlet 20 to discharge the sorted unslender objects from the airstream sorting vessel 1 opens at the lower end of the tilted meshed screen 2 in the airstream sorting vessel 1 to which the sorted unslender objects flow down. A discharge pipe 21 connects the outlet 20 to the gas supply cylinder 12. The discharge pipe 21 has a compressed gas supply nozzle 22 to supply a laminar stream of compressed gas from a separately prepared compressor or other gas supply unit. The nozzle 22 is vertically slidable to adjust the amount of opening in the outlet 20 according to the size of the objects to be discharged from the airstream sorting vessel 1. A vibrating feeder 23 which supplies a mixture of slender and unslender objects is disposed above the upper end of the meshed screen 2 tilted in the airstream sorting vessel 1. 
     The airstream sorting apparatus described here also has a unslender objects sorting apparatus 24 that is disposed alongside the airstream sorting vessel 1 and the slender objects collecting vessel 3 disposed therebelow. An accelerating cylinder 26 having a constricted interior is connected to above the point where the discharge pipe 21 is connected to the gas supply cylinder 12 through a flanged joint 25. A cylinder 28 is disposed thereabove through a flanged joint 27. The cylinder 28 has an integrally formed floating objects collecting cylinder 30 with a greater cross-sectional area that has a meshed screen 31 to cover the top thereof to prevent the scattering of floating objects and an annular channel 32 provided therearound to discharge the floating objects. 
     A recovery cylinder 36 having a space to temporarily collect unslender objects formed between two vertically spaced movable dampers 37 and 38 is connected to below the joint between the gas supply cylinder 12 and gas supply pipe 11 through a flanged joint 35. Also, an unslender objects discharge cylinder 40 is connected to the recovery cylinder 36 through a flanged joint 39. 
     To perform sorting using the airstream sorting apparatus described above, a required amount of air is supplied from a separate blower to the primary gas supply pipe 11, while a compressed gas supply nozzle 22 emits a laminar stream of compressed gas from the compressed gas supply unit to prevent the reversing of the primary gas into the discharge pipe 21. The opening of the damper 14 is then adjusted to supply an appropriate amount of air for moving and sorting a mixture of slender and unslender objects in the airstream sorting vessel 1 from the gas supply cylinder 12 through the branch cylinder 13 and the slender objects collecting vessel 3. At this time, the dampers 7 and 8 in the slender objects recovery cylinder 6 and the dampers 37 and 38 in the unslender objects recovery cylinder 36 are closed. 
     In this state, the vibrating feeder 23 at the top of the airstream sorting vessel 1 supplies a mixture of slender and unslender objects to the higher end of the tilted meshed screen 2. Then, a turbulent air flow supplied from below the meshed screen 2 floats the mixture thereover in the airstream sorting vessel 1. 
     The volume of air supplied to the airstream sorting vessel 1 must be large enough to cause the mixture to repeat floating and stalling. Although the mixture sometimes contains highly floatable objects, even such objects do not scatter away because the upwardly flaring airstream sorting vessel 1 greatly decreases the flow speed of the ascending airstream. 
     The updraft floats the mixture of slender and unslender objects supplied to the higher end of the tilted meshed screen 2 on the left of the airstream sorting vessel 1 shown in FIG. 1. Because the buoyancy of the updraft is relatively small, the objects stall and fall soon, and then float again, thus repeating the cycle. Stalling slender objects have a tendency to fall longitudinally in the direction in which gravity works. Slender objects falling in this way pass through the meshes of the meshed screen 2 into the slender objects collecting vessel 3 and collect on the damper 7 disposed therebelow. 
     Non-slender objects move downward (to the right in FIG. 1) over the tilted meshed screen 2 while repeating ascending and descending and finally reaches the unslender objects outlet 20. The laminar stream of compressed air emitted from the compressed gas supply nozzle 22 carries the unslender objects to the gas supply cylinder 12. 
     If necessary, the airstream sorting vessel 1 or the meshed screen 2 may be vibrated to facilitate the travel of the unslender objects in the airstream sorting vessel 1. 
     The slender objects collecting on the damper 7 in the slender objects collecting vessel 3 are dropped onto the damper 8 by opening the damper 7 at appropriate intervals. After closing the damper 7 and opening the damper 8, the slender objects are then discharged from the slender objects discharge cylinder 10 directly onto a discharge conveyor, feeder or hopper. Thus, the slender objects are taken out without affecting the flow of the airstream in the slender objects collecting vessel 3. 
     When the unslender objects reach the gas supply cylinder 12, less floatable objects stall and fall through the gas supply cylinder 12 onto the damper 37, whereas more floatable objects are accelerated in the accelerating cylinder 26 and move up to the floating objects collecting cylinder 30 through the cylinder 28. With the flow speed of the airstream greatly decreased in the cylinder 30 having a large cross-sectional area, the floating objects are discharged from the annular channel 32. The floating objects thus discharged may be transferred directly onto a belt conveyor, feeder, hopper or chute. 
     Like the slender objects on the damper 7, the less floatable objects collecting on the damper 37 are dropped onto the damper 38 by opening the damper 37. By opening the damper 38 after closing the damper 37, the less floatable objects may then be transferred directly onto a belt conveyor, feeder or hopper. 
     The airstream sorting apparatus just described can intermittently supply a required amount of secondary gas by closing the damper 14 in the branch cylinder 13, supplying a secondary gas from a separately prepared blower through the secondary gas supply pipe 16, and intermittently opening the damper 17. This intermittent supply of the secondary gas provides more efficient sorting by forcibly floating and dropping the objects to be sorted.