US 3809239 A
A magnetic separator is located at the discharge end of a refuse conveyor. The separator includes a continuous belt revolving in a closed path and having a curve in its path other than at its head or end pulley. A magnetic assembly generates a magnetic field at the belt curve and on both the upstream and downstream as sides thereof. The refuse conveyor runs at an angle toward and discharges its burden into the belt in the upstream portion of the magnetic field. Magnetic material in the burden is attracted to the belt and non-magnetic material falls away. The magnetic material travels with the belt around the curve causing some agitation to dislodge any non-magnetic material being carried along with the magnetic material. Downstream of the curve, the belt, and the magnetic material, move out of the magnetic field whereupon the magnetic material falls away from the belt. The magnetic separator is supported above a receptacle into which the thus separated magnetic and non-magnetic materials fall into segregated areas. The separator's position is adjustable horizontally to accommodate different levels of burden on the refuse conveyor.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Barrett et al.
[451 May 7,1974
[ MAGNETIC REFUSE SEPARATOR  Inventors: William T. Barrett; Newton I.
Potter, both of Waukesha, Wis.
 Assignee: Wehr Corporation, Milwaukee, Wis.
 Filed: Dec. 26, 1972  Appl. No.: 318,622
Hoffman 209/223 A Mayer et al 209/1 11.8
Primary Examiner-Allen N. Knowles A trqtnqzfias'ltter E e Mi ba lfi stfl F sh ABSTRACT A magnetic separator is located at the discharge end of a refuse conveyor. The separator includes a continuous belt revolving in a closed path and having a curve in its path other than at its head or end pulley. A magnetic assembly generates a magnetic field at the belt curve and on both the upstream and downstream as sides thereof. The refuse conveyor runs at an angle toward and discharges its burden into the belt in the upstream portion of the magnetic field. Magnetic material in the burden is attracted to the belt and nonmagnetic material falls away. The magnetic material travels with the belt around the curve causing some agitation to dislodge any non-magnetic material being carried along with the magnetic material. Downstream of the curve, the belt, and the magnetic material, move out of the magnetic field whereupon the magnetic material falls away from the belt. The magnetic separator is supported above a receptacle into which the thus separated magnetic and non-magnetic materials fall into segregated areas. The separators position is adjustable horizontally to accommodate different levels of burden on the refuse conveyor.
12 Claims, 3 Drawing Figures Pmmmm 1524 3809289 ,sum 1 or 2 1 MAGNETIC REFUSE SEPARATOR BACKGROUND OF I INVENTION This invention relates to magnetic separators and, more particularly, to magnetic separation of magnetic material in refuse.
With more and moreemphasis being placed on recycling, it is-becoming more desirable'to recover salvageable articles from otherwise discarded material. Much ofthe metallic material discarded as refuse can generally be recycled for one purpose oranother, provided it can be efficientlyseparated from the remainder of the refuse. The portions intended to be recaptured being metallic are generallyalsoma'gnetic sothat magnetic separation isa possibility-for recapturenl-iowever, the remainder of the refuse, i.e, other than the-metallic articles, although'generally-not magnetic (e.g., paper), is usually light andtangled "withthe 'magnetic portions and thus is carried along with the magnetic material making complete separationdifficultif not impossible.
Also, in some cases it'maybe desired to separate the lighter material (e.g., paper) for'recycling andagain, it is desirable to separate the lighter material from the metallic. i
There are various designs of magnetic separators, none of which, to the inventors knowledge, are well suited to this refuse separator problem because of an inability to insure thorough separation of magnetics from non-magnetics in that environment.
This invention is concerned with this problem and has as one'of its objects the provision-ofeffective separation of the magnetic portions of refuse fromthe nonmagnetic portions thereof.
SUMMARY OF INVENTION For the achievement of that and other objects, this invention proposes a magnetic separator'havinga continuous belt moving past a magneticassembly which generates a magnetic field through which the belt moves. The belt is supported such thatit has acurve in the lower portion of its path of movement and a straight line portion upstream of the curve. The magnetic assembly is located and generates amagnetic field in the area of the straight line portionand .the curve. The magnetic assembly, and the field generated thereby, extend onbo'th the upstream anddownstream sides of the curve, i.e.,-relative-to the direction of travel of the belt. On the up'streamside of the curvethe belt follows a straightline pathand, ifdesired, the belt may also follow a straight line path on the downstream side of the curve. Materialbeing attracted to the belt by the magnetic assembly and thus traveling along with the belt, must negotiate the curve and at the curve there will be some displacement, i.e.,agitation, of thematerial traveling with the belt. This'agitation tends to dislodge any non-magnetics being carried along with the magnetics.
In a preferred embodiment the magnetic assembly also includes a magnetic portion at the curve to insure a magnetic field in that area strongenough to prevent the magnetics from falling completely away from the belt. Also, agitation is further enhanced by the magnetic assembly presenting alternating polarities to the belt and thus to thematerial attracted thereto.
Preferably the belt on both the upstream'and downstream sides of the curve isdisposed'at an angle to the horizontal thereby taking better advantage of gravity, with the agitation, to achieve complete separation.
The supply conveyor which delivers the refuse to the separator runs at an angle to the upstream portion of the magnetic field and the portion of the belt in that area. It is advantageous to mount the magnetic separator for movement toward and away from the end of the supply conveyor to accommodate different burden depths on the conveyor.
To counteract wear of the belt, the belt can be driven from the head pulley so that the back or nonworking side of the continous belt loop is under tension and the lower or working side can be relatively slack. In addition, or as an alternative, rollers can be provided at the curve to support the belt.
DESCRIPTION OF DRAWINGS FIG. 1 is a side view of a combination refuse separator and supply conveyor partially in section;
FIG. 2 is an end view of the refuse separator of FIG. 1; and
FIG. 3 is'a side view similar to FIG. 1 but illustrating an alternative construction and arrangement of the refuse separator.
DESCRIPTION OF PREFERRED EMBODIMENT With particular reference to the drawings; a refuse separator 10 is illustrated in combination with a supply conveyor 12, receptacle l4 and a splitter baffle 16. The function of the receptacle and splitter baffle is to physically segregate separated magnetic and non-magnetic material, therefore no particular form of either is necessary and in fact only one of the two could be used if desired.
The refuse separator is intended to receive burden 18 from supply conveyor 12 and carry the magnetic portion of the burden over splitter baffle 16 while the nonmagnetic material falls, by reason of gravity, into receptacle 14. To this end, the separator includes belt 20 which travels in a counterclockwise manner around idler rollers 22 and 24 and head and end pulleys 26 and 28. Head pulley 26 is connected to drive motor 30 through a belt drive 32 and a gear box so that the head pulley becomes the drive member through which the driving force is imparted to belt 20. In this manner, the belt travels in a continuous, closed path under'the influence of drive pulley 26. As viewed in FIG. 1, the closed path has an upper portion (between end pulley 28 and idler 22) and a lower portion (between head pulley 26 and end pulley 28).
Magnetic assembly 36 is located within the area defined by belt 20. The magnetic assembly consists of a lead magnet 38 having a central core 40 surrounded by an electrical coil'42 and housed within a U-shaped incross section housing 44 with core 40 engaging the backplate 46 of the housing. This is a conventional electromagnet construction and when coil 42 is energized the end of core 40 adjacent belt 20 will assume one magnetic polarity, e. g. north, and the outer ends of sides 48 and 50 of the housing will assume an opposite magnetic polarity, south. Plate 52 is a pole piece provided to concentrate the emanation of flux at the belt.
Downstream of the lead magnet assembly is a trailing magnetic assembly consisting of a backplate 54 and four magnetic assemblies, 56, 58, 60, and 62 projecting from the backplate 54 toward the belt. Each of the magnetic assemblies can be made of permanent magnetic material such as barium titanate waffers, which are magnetized through their thickness dimension, i.e., at right angles to backplate 54, and stacked with the thickness dimension of each magnetic waffer in an assembly 56, 58, 60, or 62 extending in a common direction. By controlling the orientation of the magnetic waffers the magnetic polarity presented by each of the magnetic assemblies to the belt can be controlled so that, for example, anorth magnetic polarity is presented by each of assemblies 56 and 60 and a south magnetic polarity is presented by each of assemblies 58 and 62. It will be noted that the alternating polarity started at the lead magnetic assembly is maintained through the trailing magnetic assembly.-
It will be appreciated further that the entire magnetic assembly could be made of electromagnets or permanent magnets as desired or as illustrated in it can be a combination of permanent and electro. To-complete the magnet assembly a plate, either in one piece or a weldment, 64 extends between the magnetic assembly and the inside surface of belt 20.
The idler rollers and pulleys and head pulley.26 to gether with the magnetic assembly are all supported from a common frame structure, a portion of which, 66 and 68, is illustrated in FIG. 2. Since a showing of the complete structural framework of the refuse separator is not necessary to an understanding of this invention,
' this general description of the support structure is believed to be adequate.
With reference to FIG. 1, magnet assembly 36 generates a magnetic field at belt 20 and at the lower portion of the path through which the belt travels. Conveyor 12 is arranged so that it discharges burdenl8 into this magnetic field and the magnetic material contained in the burden is attracted to the belt 20 in the area of lead magnet 38. The non-magnetic material such as paper, will fall by gravity into receptacle l4 and the magnetic material travels with belt 20 beyond splitter 16 where the magnetic field terminates. The magnetics are discharged on the side of the splitter baffle oppositeto the receptacle. Also, to take advantage of the fact that once the magnetics are attracted to the belt less magnetic force is required to hold them on the belt than to attract them initially, the magnets can be made to diminish in strength from lead magnet 38 through the trailing magnets. That is, magnetic assemblies 56, 58, 60, and 62 can be .made progressivelyweaker from the curve toward end pulley 28..
Paper and like non-magnetic material, being relatively light, is extremely prone to being tangled with the magnetic material and carried along with it into engagement with and on belt 20 such that it cannot fall into receptacle 14. To provide means for dislodging this entrapped non-magnetic material, this invention intends to'provide agitation of the burden carried by belt 20 without losing the magnetic material. To this end, a curve 70 is provided in the lower portion of the path of belt 20 in the area of the magnetic assembly.
With respect to the direction of travel of belt 20 and, still in the lower portion of the path, the belt follows straight line paths on both the upstream and downstream sides of the curve and all lead magnet 38 is located upstream of curve 70 and the trailing magnet portion of the magnetic assembly is located downstream of the curve. Because of the curve 70, the material adhered to the belt must change direction at the ually or through curve and since the non-magnetic material does not have the magnetic attractive force to hold it on the belt, it tends, due to centrifugal force, to proceed in a straight line trajectory rather than make the curve.
Also it has been observed that, again due to centrifugal force, some physical separation of the magnetic material from the belt occurs at the curve, but not completely from the magnetic field so that the magnetic material returns to the belt after the curve has been negotiated, and this causes agitation at the curve which further tends to dislodge the non-magnetic material.
Also, the preferred embodiment illustrated in FIG. 1 shows the upstream and downstream portions of the belt adjacent curve both positioned at an angle to a horizontal plane, this arrangement makes maximum use of the force of gravity in separating the nonmagnetics. That is, the turn at the curve utilizes basic inertia and gravity to achieve some separation and the belt proceeding generallyupward from the curve increases the pull of gravity on the non-magnetic materials to enhance separation.
For effective introduction of the burden from supply conveyor 12 to the magnetic separator, conveyor 12 is arranged at an angle to the magnetic separator. Conveyor 12 is arranged at an angle for the horizontal so that the burden comes into the belt in the area of lead magnet 38 at an angle. This brings the material into the belt generally in the direction of the flux lines making up the magnetic field for most effective separation.
In order to accommodate different depths ofburden, the entire refuse separator is supported for horizontal movement toward and away from the conveyor 12. More specifically, and with reference to FIG. 2, a pair of support brackets 72 and 74 extend from frame member 66 and 68 on opposite sides of the refuse separator. Two pairs of these support brackets are provided. One at the head end and one at the opposite end of the magnetic separator but only one is illustrated in the drawings. The support brackets have an elongated channel member 76 and 78 attached to their undersides and each supports a roller 80 and 82. The rollers engage I- beam rails 84 and 86 which aremounted on frames 88 and 90. The refuse separator can then bemoved horizontally toward and away from the discharge end of the supply conveyor, this can be accomplished eithe'r'mansome suitable mechanical arrangement.
A plurality of conventional lugs 92 areprovided on the working face of belt 20 to assist in carrying the material along with the belt.
At this point, it should also be noted that certain advantages attach to utilizing the head pulley 26 as thedrive pulley. By doing this, it is the backside 94 of the belt which is maintained under tension and the working side of the belt, i.e., that passing through the magnetic field, can be supported to hang relatively slack. This has a tendency to minimize belt wear.
Also, the alternating magnetic polarities along the path of travel of the belt provide agitation of the magnetic material attracted to the belt to further enhance separation. That is, the magnetics being forced to pass through alternately different magnetic fields will, in effect, roll around and not hold a stationary position on the belt.
FIG. 3 illustrates an alternative construction of the refuse separator and arrangement with respect to supply conveyor 12, receptacle 14 and splitter baffle 16.
In this embodiment, the upstream portion 96 of belt is arranged at a sharper angle to the horizontal than in FIG. 1 and the downstream portion 98 is in a horizontal plane. Magnetic assembly 102 again includes lead magnet 104 which generates a magnetic field at the end of conveyor 12 and in the area of the upstream portion 96 of the belt and a trailing portion 106 which is positioned downstream of the curve and generates a magnetic field in that area. These magnetic assemblies can be constructed the same as illustrated in connection with FIG. 1 again maintaining the alternating magnetic polarities.
In the FIG. 3 embodiment a third magnetic assembly 108 is provided at curve 100 to insure an adequate magnetic field at the curve to prevent loss of the magnetics. The additional magnetic assembly 108 maintains the alternating polarities discussed previously.
In the FIG. 3 embodiment the drive for belt 20 is provided through end pulley 110. With this arrangement, the working portion of the belt will now be under tension and to miminize wear at curve 100 a plurality of stainless steel rollers 112 are provided in that area as support for the belt.
Again, the refuse separator of FIG 3 can be positioned for horizontal movement relative to the end of conveyor 12 and it will again be noted that the burden is discharged into the face of'belt portion 96 so that it is generally in line with the magnetic lines of flux making up the magnetic field.
As in FIG. 1, magnetics will be attracted to the lower portion of the path of travel of belt 20 as the burden is discharged from supply conveyor 12. The nonmagnetics fall into receptacle l4, and the magnetic material is agitated as it travels along with the belt through the magnetic field to further dislodge nonmagnetics before splitter 16 is reached at which point the magnetics fall from the belt behind the splitter baffle.
Although this invention has been illustrated and described in connection with particular embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.
We claim: I
l. A magnetic separator comprising, in combination,
means supporting said belt for movement around a closed path in continuous fashion with saidpath having an upper and a lower portion,
a magnetic assembly having an extension along said lower portion of said closed path,
means supporting said magnetic assembly to generate a magnetic field along said lower portion of said closed path and through which said belt moves,
said means supporting said belt also defining, in said lower portion of said path, a curve and, upstream of said curve, a generally straight line path along which said belt moves up to said curve,
and said magnetic assembly disposed with a portion thereof located, relative to the path of travel of said belt, on both sides of said curve so that magnetic material in said field is attracted to and travels with said belt along said straight line path and around said curve.
2. The magnetic separator of claim 1 wherein said magnetic assembly also includes a portion located at said curve to generate a magnetic field at said curve and maintain an attractive force on magnetic material traveling with said belt around said curve.
3. The magnetic separator of claim 2 including a plurality of idler rollers at said curve for engaging said belt.
4. The magnetic separator of claim 1 wherein said magnetic assembly varies in magnetic intensity the downstream portions thereof generating a lesser strength magnetic field than the upstream portions thereof.
5. The magnetic separator of claim 1 wherein said magnetic assembly includes a head pulley and an end pulley located, relative to the path of travel of said belt, upstream and downstream, respectively of said curve, including drive means for moving said belt through said closed path, said drive means connected to and rotating said drive pulley to drive said belt,
and wherein said belt is supported in a relatively slack condition between said head and end pulleys and around said curve to minimize belt wear.
6. The magnetic separator of claim 1 wherein the portions of said belt upstream and downstream of said curve are both supported for movement along generally straight line paths and both paths are at an angle to the horizontal.
7. The magnetic separator of claim 1 wherein the portion of said belt upstream of said curve is at an angle to the horizontal.
8. The magnetic separator of claim 1 in combination with a supply conveyor for delivering a burden consisting of magnetic and non-magnetic material to said belt upstream of said curve and into the magnetic field generated by'said magnetic assembly,
means for supporting said magnetic separator over a receptacle into which non-magnetic material falls,
and a splitter baffle located in the area of the downstream end of said magnetic assembly so that magnetic material adhered to said belt is held on said belt up to said splitter baffle after which it leaves said magnetic field and falls from said belt 9. The magnetic separator of claim 1 in combination with a supply conveyor for delivering a burden consisting of magnetic and non-magnetic material to said belt upstream of said curve and into the magnetic field generated by said magnetic assembly, said supply conveyor disposed at an angle to the portion of said belt upstream of said curve,
and means for moving said magnetic separator relative to said supply conveyor.
10. The magnetic separator of claim 8 wherein said I magnetic assembly also includes a portion located at said curve to generate a magnetic field at said curve and maintain an attractive force on magnetic material traveling with said belt around said curve.
11. The magnetic separator of claim 8 wherein the portion of said belt upstream of said curve is at an angle to the horizontal.
12. The magnetic separator of claim 1 in combination with a supply conveyor for delivering a burden consisting of magnetic and non-magnetic material to said belt upstream of said curve and into the magnetic field generated by said magnetic assembly.
222 33 UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTION Patent No. 3 809 239 Dat d May -'7 1974 Inventor(s) William T. Barrett and Newton I. Potter It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 3, Lines 60-63, after "20" delete:
"and, still in the lower portion of'the path,
the belt follows straight line paths on both the upstream and downstream sides of the curve and all";
Column 3, Line '59, after "20" insert:
--and, still in the lower portion of the path, the belt follows straight line paths on both the upstream and downstream sides of the curve and all-.
Signed and sealed this 17th day of Septemberl974.
" (SEAL) Attest:
MCCOY M. GIBSON JR. (2. MARSHALL DANN Attesting Officer Commissioner of Patents