Patent Publication Number: US-4317717-A

Title: Nonmagnetic conductive material separating apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a nonmagnetic conductive material separating apparatus preferably adapted for separating a nonmagnetic conductive material represented by aluminum cans from a mixture material collected as waste. 
     2. Description of the Prior Art 
     A mixture material collected as waste, generally speaking, is supplied into a magnetic sorter, so that a magnetic material represented by iron pieces is removed from the mixture material. The mixture material from which the magnetic material has been removed by the magnetic sorter is largely classified into a nonmagnetic nonconductive material represented by wood pieces and waste paper, and a nonmagnetic conductive material represented by aluminum cans. To the effect that the former is separated from the latter, the mixture material is supplied into the nonmagnetic conductive material separating apparatus. 
     The inventor of the present invention has proposed a separating apparatus in U.S. Application Ser. No. 59,648, now U.S. Pat. No. 4,230,560. The separating apparatus includes a drum rotating in one direction about the longitudinal central axis inclined with respect to the horizontal plane and having an equal inner diameter throughout the length thereof; a chute through which a mixture material to be separated is thrown into the drum from the upper opening thereof; and a means for generating a shifting magnetic field for exerting an electromagnetic force opposite to a rotating direction of the drum on the conductive material contained within the mixture material moving toward the lower opening of the drum. 
     In the separating apparatus, the mixture material thrown from the upper opening of the drum through the chute into the drum is forced upward along the inner peripheral wall of the drum in the direction of rotation of the drum due to friction relative to the inner peripheral surface of the rotating drum, and then slid down therefrom due to its own weight. The mixture material is moved up and down in the drum in a meandering fashion in the state of being deviated toward the direction of rotation along the bottom wall of the drum toward the lower opening. During the above-described movement, the mixture material passes a magnetic field zone produced by the magnetic field generating means. In the magnetic field zone, the conductive material receives the electromagnetic action, so as to be separated from the nonconductive material. In order to increase the separation efficiency by the action of the electromagnetic force, it is desirable that the conductive material and the nonconductive material which are interwined with each other be loosened before the mixture material arrives at the magnetic field zone. 
     In the prior art separating apparatus described above, the conductive material twined about or held on the nonconductive material, such as waste paper has been partially loosened, and hence, both are likely to move through the drum integrally, resulting in poor separation efficiency. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the present invention to provide a nonmagnetic conductive material separating apparatus, which is capable of separating the nonmagnetic conductive material from the nonmagnetic nonconductive material with a high separation efficiency. 
     It is another object of the present invention to provide a nonmagnetic conductive material separating apparatus, wherein the separation efficiency is greatly increased, without increasing the size of the apparatus. 
     To attain the above-described objects, there is provided according to the present invention a separating apparatus which comprises a means for increasing an agitation effect for a mixture material supplied in the drum, so that the mixture material entangled in the form of lump can be loosened by the means, with the result of the improved separation efficiency. 
     In a first embodiment of the invention, the unidirectionally rotating drum is provided with a shoulder portion on the inner peripheral surface thereof, as the agitation effect increasing means, so that the movement of the mixture material from the upper opening of the drum toward the lower opening thereof is subjected to change by the shoulder portion, thereby loosening the nonmagnetic conductive material and the nonmagnetic conductive material, which are intertwined with each other, thereby increasing the separation efficiency by the electromagnetic force produced by the shifting magnetic field generating means. 
     In a second embodiment of the invention, as means for increasing the agitation effect, a means for throwing a mixture material from the upper opening of a unidirectionally rotating drum into the drum is biased from the vertical plane including the axis of rotation of the drum to one side of said vertical plane depending on the direction of rotation of the drum. A dropping point in the drum, of the mixture material which is supplied into the drum by the mixture-material supply means is deviated from the vertical plane to either right or left side of said vertical plane as view from the lower opening of the drum depending on the direction of rotation of the drum, so that a distance from the dropping point in the drum, of the mixture material to a point, at which the mixture material forced up along the inner peripheral wall of the drum is first dropped due to its own weight, can be increased. Thus, the distance of the meandering movement of the mixture material is increased without increasing the length of the drum or the inner diameter thereof, with the result that the agitation effect by the rotating drum as well as the separation effect by the electromagnetic force of the magnetic field generating means are increased. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view, partly broken away, of a nonmagnetic conductive material separating apparatus according to the present invention; 
     FIG. 2 is a transverse cross sectional view taken along the line II--II of FIG. 1; and 
     FIG. 3 is a developed view of a drum, showing the course of movement of the mixture material in the drum shown in FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A separating apparatus 10 according to the present invention comprises: a drum 12 open at opposite ends and made of a nonmagnetic material; a means 14 for generating a shifting magnetic field; and a frame 16 inclined with respect to the horizontal plane. 
     The drum 12 includes a diametrically small portion 12a, a diametrically intermediate portion 12b adjoining to the diametrically small portion 12a, and a diametrically large portion 12c adjoining to the diametrically intermediate portion, whereby circumferentially extending shoulder portions 18 and 20 are formed along the inner peripheral walls between the diametrically small portion 12a and the diametrically intermediate portion 12b, and between the diametrically intermediate portion 12b and the diametrically large portion 12c, respectively. Annular guide members 22 and 24 are provided on the outer peripheral surfaces of the small diameter portion 12a and the intermediate diameter portion 12b, respectively, and the open end of the large diameter portion 12c is divergent in the longitudinal direction of the drum, thereby forming a divergent edge 12d. 
     A pair of drive rollers 26 and a pair of driven rollers 28 are rotatably mounted on brackets 30, which in turn are supported on the frame 16, these drive rollers and driven rollers being fitted into the annular guide members 22 and 24 on the drum 12 (only one drive roller and only one driven roller are shown in FIG. 1). The drum 12 is placed on the drive rollers and driven rollers maintained in engagement with the annular guide members 22 and 24, respectively. The drum 12 is thus supported above the frame 16 in a tilted fashion, with the longitudinal central axis 32 thereof making an angle θ with respect to the horizontal plane, and the opening 34a of the diametrically small portion 12a being located at a higher level than the opening 34b of the diametrically large portion 12c. The rotational force of a drive motor 36 provided on the frame is transmitted by way of a chain 38 to the drive rollers 26, whereby the drum 12 is rotated clockwise about the central axis 32 thereof, as viewed from the lower opening 34b  of the drum 12 in FIG. 2. 
     The shifting magnetic field generating means 14, in the embodiment shown in FIGS. 1 and 2, includes an annular member 40 surrounding the diametrically large portion 12c of the drum coaxially therewith, and a plurality of permanent magnets 42a and 42b embedded in the inner peripheral wall of the annular member. The permanent magnets 42a and 42b are so arranged that, in the magnetic pole faces opposing the outer periphery of the diametrically large portion 12c, one magnetic poles alternate with the other magnetic poles in the circumferential direction of the annular member, as best seen in FIG. 2. The boundaries between adjacent magnetic poles of respective permanent magnets 42a and 42b extend in parallel to the central axis 32 of the drum 12, as shown in FIG. 1. An annular guide member 44 is provided on the outer peripheral surface of the annular member 40. The annular member 40 is placed on a pair of drive rollers 46 supported on the frame 16 and maintained in engagement with the annular guide member 44. The rotational force of drive motor 48 supported on the frame 16 is transmitted via a chain 50 to the drive rollers 46, whereby the annular member 40 can be rotated about the central axis 32 in a reverse direction to the direction of rotation of the drum 12, namely, counterclockwise in FIG. 2. 
     Rotation of the annular member 40 causes the magnetic field generated by the permanent magnets 42a and 42b embedded in the inner peripheral wall of the annular member to rotate opposite to the direction of rotation of the drum, around the diametrically large portion 12c of the drum 12. The rotating magnetic field induces an eddy current on the nonmagnetic conductive material moving along the bottom wall of the diametrically large portion 12c of the drum 12 toward the lower opening 34b thereof, thereby exerting on the nonmagnetic conductive material an electromagnetic force F along the direction of rotation of the rotating magnetic field, namely, opposite to the direction of rotation of the drum. The electromagnetic force F is proportional to the speed of rotation of the rotating magnetic field. If the speed of the annular member 40 rotating independently of the drum 12 is increased, the electromagnetic force F is intensified without causing a strong centrifugal force to act on the mixture material supplied into the drum 12. 
     The electromagnetic force F consists of only transverse components parallel to the direction of rotation of the rotating magnetic field, in the case where the boundary lines between adjacent magnetic poles are substantially in parallel to the rotational axis 32 of the drum, as shown in FIG. 1. Where the boundaries between the adjacent magnetic poles are substantially inclined with respect to the rotational axis 32 of the drum 12 in a manner to be twisted along the rotational axis of the drum, the vertical components toward the lower opening 34b are contained in the electromagnetic force F. A linear motor which covers the lower part of the diametrically large portion 12c may be employed, as the shifting-magnetic-field generating means 14. 
     A chute 52 is inserted into the upper opening 34a of the drum 12 as a means for throwing the mixture material being separated into the drum 12. The chute 52, as is obvious from FIG. 2, is biased from the vertical plane 54 which includes the rotational axis of the drum to one side of the vertical plane 54 depending on the direction of rotation of the drum 12, namely, in the right half part of the upper opening 34a of the drum 12 rotating in the right-handed direction, as viewed from the lower opening 34b of the drum, in the embodiment of FIG. 2. In case the drum 12 is rotated counterclockwise, as viewed from the lower opening side 34b of the drum, then the chute 52 should be located in the left half part of the upper opening 34a, as viewed from the lower opening 34b of the drum. 
     The mixture material from which the magnetic material represented by iron pieces has been removed beforehand is supplied through the chute 52 into the drum 12, as described above. The mixture material being thrown into the drum is largely classified into the nonmagnetic conductive material 56 represented by aluminum cans and the nonmagnetic nonconductive material 58 represented by waste paper or wood pieces. The mixture material is continuously dropped from the chute 52 into the drum 12, so that the mixture material can be separated into the nonmagnetic conductive material and the nonmagnetic nonconductive material. 
     FIG. 3 is a developed view of the drum 12, wherein the course of movement of the mixture material dropped from the chute 52 into the drum 12 is diagrammatically shown by a broken line. The mixture material dropped to a point 60 on the bottom of the diametrically small portion 12a of the drum 12 is moved from the point 60 toward the vertical plane 54 along a line 62a by rotation of the drum 12 as well as by its own weight, and thence, moved in a direction opposite to the point 60 to be put upward along the inner peripheral surface of the drum along a line 62b due to friction relative to the inner peripheral wall of the drum 12. When the mixture material reaches a point 64 at which the weight of the mixture material itself exceeds the frictional force relative to the inner peripheral surface of the drum 12, the mixture material is in turn moved toward the vertical plane 54 as shown by a line 62c, and then moved along the bottom wall of the drum 12 in a meandering fashion along lines 62 d, e . . . due to its own weight within the range of angle formed by the vertical plane 54 and the point 64, through the diametrically small portion 12a, the diametrically intermediate portion 12b and the diametrically large portion 12c, eventually to the lower opening 34b of the large diameter portion. 
     Due to the fact that the conductive material 56 of the mixture material has a configuration liable to roll, such as aluminum cans, has a larger size and higher specific gravity than those of the nonconductive material 58, and has a smaller coefficient of friction than that of the nonconductive material, the conductive material 56 tends to be biased toward the vertical plane 54, as compared with the nonconductive material 58, during the meandering movement of the mixture material which starts from the dropping point 60 in the drum. For these reasons, the chute 52 is located in the right part portion of the drum, which is biased from the vertical plane 54, as described, so that the mixture material can be dropped to the point 60 remote from the vertical plane 54, thereby increasing by a distance equivalent to the length of the line 62a the distance of movement of the mixture material which leads from the dropping point to the magnetic field zone, as compared with that in the prior art device. Consequently, the density of the conductive material in the mixture material greatly increases on the side nearer to the vertical plane 54 during the meandering movement of the mixture material to the magnetic field zone. 
     The mixture material passes through the shoulder portions 18 and 20 during the meandering movement thereof in the drum. In the shoulder portions 18 and 20, the mixture material moving in the form of lump is inverted and/or receives a different circumferential speed accruing from a difference in inner diameter between the diametrically small portions and the diametrically intermediate portion, and hence the movement of the mixture material is subjected to change at each shoulder portion 18,20. Consequently, the conductive material 56 put on or twined about waste paper is released from the nonconductive material 58 such as waste paper and comes to the magnetic field zone in the diametrically large portion 12c of the drum. 
     In the magnetic field zone, the conductive material 56 receives the electromagnetic force F acting in an opposite direction to the rotational direction of the drum 12, as described above, and the nonconductive material 58 by no means receives such an electromagnetic force. 
     The nonconductive material 58 is therefore carried toward the lower opening of the drum in the state of being deviated towards the rotational direction of the drum, namely, to the left side from the vertical plane 54, as viewed in FIG. 2, and discharged from the lower opening 34b of the drum 12. 
     In contrast thereto, the conductive material 56 is directed opposite to the rotational direction of the drum 12 by the action of the electromagnetic force F. In the magnetic field zone, the density of the conductive material 56 in the mixture material is large on the side near to the vertical plane 54, and the conductive material twined about the nonconductive material becomes loosened. The electromagnetic force F is thus permitted to effectively act on the conductive material 56 as a force of separating same from the nonconductive material 58, whereby the conductive material can be positively directed opposite to the rotational direction of the drum 12. The conductive material 56 is discharged from the right side of the lower opening 34b, being biased from the vertical plane 54, as viewed in FIG. 2, and successively recovered separately from the nonconductive material. 
     The chute 52 may be replaced by an oscillation feeder or a belt conveyor, as long as the mixture material supply opening is biased to one side of said vertical plane depending on the direction of rotation of the drum 12. 
     In the embodiment described, two circumferential shoulder portions 18 and 20 are provided along the inner peripheral walls between diametrically different portions. The number of the shoulder portions may be decreased to one or increased to more than three, as the case may be. In place of the circumferential shoulder portions, shoulder portions extending lengthwise of the drum may be provided along the inner peripheral wall of the drum equal in diameter throughout the length thereof. 
     The separating apparatus 10 may incorporate a magnetic sorter so as to thoroughly remove from the mixture material the conductive material residual therein. 
     Although in the embodiment of FIGS. 1 and 2, two shoulder portions 18 and 20 are provided in the drum, and the mixture-material supply means 52 is biased from the center of the drum, either of these methods may be used individually, to provide the shoulder portions and to locate the mixture supply means in a portion biased from the center of the drum. 
     According to the present invention, by the shoulder portion provided along the inner peripheral wall of the drum, the movement of the mixture material is subjected to change when passing the shoulder portion, whereby the nonmagnetic conductive material held on or twined about the nonconductive material during the travel in the drum is released from the nonmagnetic nonconductive material or becomes loosened before the mixture material reaches the moving magnetic field zone. Consequently, the electromagnetic force produced by the shifting magnetic field is caused to effectively act on the conductive material as a force of separating the conductive material from the nonconductive material, thereby preventing the conductive material from being carried away by the nonconductive material as the former is twined about the latter, thus improving the separation efficiency. 
     According to the present invention, the means for supplying a mixture material being separated into a drum disposed in a tilted fashion is provided, with the mixture supply opening thereof biased from the vertical plane including the rotational axis of the drum to one side of the vertical plane depending on the rotational direction of the drum, thereby increasing a distance for meandering stroke of the mixture material leading from the dropping point in the drum to the shifting magnetic field zone therein, without increasing a diameter and a length of the drum, whereby the agitation effect for the mixture material by the contact of the mixture material with the inner peripheral wall of the drum is increased. As a result, the electromagnetic force generated by the shifting magnetic field is permitted to effectively act on the conductive material as a separation force, without increasing the size of the separation apparatus itself, and with increased separation efficiency.