05/196383

06/12/1973

11/08/1971

Download PDF 3738483       PDF help

Click for automatic bibliography generation

209/44.100

209/638, 209/631, 241/DIG.038, 209/930, 209/137

B03B9/06; B07B4/02; B07B7/01; B03B9/00; B07B4/00; B07B7/00; B07B15/00

209/115,117,12,120,134-139,142,153

Lutter, Frank W.

Hill, Ralph J.

I claim

1. In a method of classifying heterogeneous shredded refuse materials:

2. In a method according to claim 1, heating air for the pneumatic separation to facilitate drying of moist materials.

3. In a method according to claim 1, receiving the lightest and softest fractions of the non-airborne materials in a receptacle nearest said point, and receiving successively heavier and harder fractions of the non-airborne materials in respective receptacles farther spaced from said point.

4. In a method according to claim 1, effecting ballistic generally stratification of the fractions of non-airborne materials in said chamber and collecting the stratified fractions in classification receptacles at the bottom of said chamber.

5. In a method according to claim 1, separating and effecting the collecting of the airborne fractions in respective vertically spaced receptacles at the far side of said chamber from said point.

6. In a method according to claim 1, driving air for separating and classifying the airborne fractions into the gravitationally descending materials at a plurality of spaced classifying zones below said point.

7. In a method according to claim 1, wherein said projecting comprises mechanically agitating and propelling the non-airborne materials below said point.

8. In a method according to claim 1, effecting suction removal of the airborne fractions from said chamber.

9. In a method according to claim 1, removing the airborne fractions from said chamber pneumatically, and classifying the respective airborne fractions in a connected series of cyclone separators.

10. In a method according to claim 1, said pneumatic separating of the airborne fractions from the non-airborne fractions comprising driving air through the gravitating materials and across said chamber, and simultaneously effecting negative pressure through duct means leading from said chamber, and thereby drawing off said airborne fractions of the materials for collecting the same.

11. In apparatus for classifying heterogeneous shredded refuse materials:

12. In apparatus according to claim 11, a receptacle nearest said point for receiving the lightest non-airborne materials, and respective receptacles spaced farther from said point to receive successively heavier fractions of the non-airborne materials.

13. In apparatus according to claim 11, said conveying means being operative to project said materials forwardly from said point at a velocity to effect substantially ballistic separation of the fractions of non-airborne materials.

14. In apparatus according to claim 13, classification receptacles at the bottom of said chamber for collecting respective fractions of non-airborne materials from stratifications effected by said ballistic projection thereof.

15. In apparatus according to claim 11, said means for collecting the airborne fractions comprising respective vertically spaced receptacles at the far side of said chamber from said point.

16. In apparatus according to claim 11, said pneumatic means including means for driving air for separating and classifying the airborne fractions into the gravitationally descending materials at a plurality of spaced classifying zones below said point.

17. In apparatus according to claim 11, said means for projecting comprising means for mechanically agitating and propelling the non-airborne materials below said point.

18. In apparatus according to claim 11, means for effecting suction removal of the airborne fractions from said chamber.

19. In apparatus according to claim 11, means for removing the airborne fractions from said chamber pneumatically including a connected series of cyclone separators for classifying the respective airborne fractions.

20. In apparatus according to claim 11, said means for pneumatic separation being operative to drive air through the gravitating materials and across said chamber, and means for simultaneously effecting a negative pressure through said duct means to draw off the airborne fractions and collect the same.

21. In apparatus according to claim 17, said mechanical agitating and propelling means comprising beaters movable in generally up and down direction on respective horizontal axes in generally vertically spaced relation.

22. In apparatus according to claim 11, receptacles in the bottom of said chamber for receiving respective non-airborne fractions of the materials and including conveyor means to remove the fractions collected in said receptacles.

23. In apparatus according to claim 11, said conveying means comprising a shaker including a screen for separating finely particulate particles from the materials before releasing the materials from said point.

24. In apparatus according to claim 11, means enclosing said chamber including a tower-like structure supporting said conveying means from adjacent the top of one side of the chamber, said enclosing means including wall structure at the opposite side of said chamber, duct means leading from said wall structure, and means effecting suction into said duct means to draw off said airborne fractions from said chamber.

This invention is concerned with classification of shredded materials, and is more particularly concerned with gravity and pneumatic classification of heterogeneous shredded municipal waste.

Disposal of refuse material, and more particularly municipal waste, which may or may not include industrial waste, presents an ever-increasing problem ecologically and economically.

Although various schemes have been proposed for sorting and processing municipal waste materials, too many such schemes involve elaborate and expensive equipment requiring excessive maintenance attention, and often limited in the scope of productivity and effectiveness as to volume, capability and capacity, particularly in the handling and processing of shredded material. Although shredders have been developed to high efficiency, the technology of separation of the heterogeneous waste materials has lagged behind.

An important object of the present invention is to overcome the foregoing and other disadvantages, defects, inefficiencies, shortcomings and problems in prior methods and apparatus and to provide new and improved method of and apparatus for separation and classification of heterogeneous shredded refuse materials, attaining important advantages as will become apparent hereinafter.

Another object of the invention is to provide new and improved shredded refuse materials classification method and apparatus by and in which refuse materials, heterogeneous as delivered to a drop-off in a chamber, are efficiently separated, classified and collected.

A further object of the invention is to provide new and improved method of and apparatus for classifying heterogeneous shredded materials combining gravity and pneumatic features.

A still further object of the invention is to provide new and improved method of and means for classifying heterogeneous shredded refuse materials, involving gravity, pneumatic and mechanical actions thereon.

Still another object of the invention is to provide new and improved method of and means for vertically stratifying classifications of shredded refuse material ballistically and pneumatically to effect collecting of the stratified materials in respective receptacles.

Yet another object of the invention is to provide a novel method of and apparatus for gravitational and pneumatic generally horizontal stratification of shredded refuse materials and recovery of the strata in respective classification receptacles.

It is also an object of the invention to provide novel method of and means for separation and classifying of heterogeneous shredded refuse materials including efficient dust removal.

Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts embodied in the disclosure, and in which:

FIG. 1 is a schematic illustration of a representative heterogeneous shredded refuse materials classifying system pursuant to the invention involving separating and generally vertically stratifying the respective classifications for recovery in respective receptacles;

FIG. 2 is a schematic illustration of another classifying system according to the present invention involving generally horizontally stratifying the materials into classifications and recovery;

FIG. 3 is an isometric view representing a desirable form of air directing device which can be rotated to achieve desired air directional flow and air currents within either classifying chamber of FIG. 1 or 2;

FIG. 4 is an isometric view showing a crank drive for the agitator device in FIG. 2; and

FIG. 5 is a schematic illustration showing a further embodiment of the invention.

According to the present invention classification of heterogeneous shredded refuse materials is adapted to be effected by conveying the materials to a tower delivery release point at a substantial height in the upper portion at one side of a classifying chamber, dropping or projecting the materials from such point into the chamber to travel through a substantial space, beyond such point driving materials-separating, flushing air in generally the direction of material input or delivery and through the downwardly gravitating materials, separating the airborne materials into classifications by size and/or weight while dropping in and crossing said space, and also separating the non-airborne materials simultaneously by weight and/or size in the space, and collecting the classified materials in respective receptacles spaced at varying distances from the release point. According to one embodiment this comprises directing fines, lightest weight non-airborne particles and soft materials such as rags into the receptacle nearest the release point, and directing successively heavier, harder and/or larger classifications of the non-airborne materials into respective receptacles farther spaced from the release point. Stratification of at least some of the materials classifications, and in particular non-airborne fractions, may be effected generally vertically and the classified materials collected in receptacles along the bottom of the classifying chamber. Combined, simultaneous gravitational and pneumatic generally horizontal stratification of at least some of the materials classifications, and in particular airborne fractions, may be effected and the classified materials collected in receptacles in generally vertical orientation at the opposite side of the classifying chamber. After thorough separation of all the shredded airborne particles from the non-airborne particles, series cyclone classification and collection may be effected. Flushing, substantially air-washing, classifying air may be driven into the dropping or ballistically moving materials at a plurality of vertically or horizontally spaced classifying zones beyond the release point. Mechanical agitation of the materials may be employed to increase or augment materials separation and classifying effectiveness of the pneumatic system. Efficient dust removal is provided for.

By way of example of apparatus for practicing the invention, and especially adapted for simultaneous ballistic and air flushing separation, generally vertical and horizontal zone classification, FIG. 1 may be referred to. Therein raw refuse materials, such as may be accumulated through municipal refuse disposal or scavenger services are supplied as through hopper means 10 to suitable grinding and/or shredding means 11 from which the heterogeneous shredded (this term being intended to include particles of materials reduced in size by breaking into small particles such as glass and other frangibles and metals) refuse materials are deposited on conveyor means such as an endless conveyor 12 having cleats 13 and by which the shredded materials are transported to a projection delivery release point in the upper portion of one side of a classifying chamber 14 in a tower-like enclosure and of substantial height and width for the intended purpose and capacity. Although only a single representative shredder 11 is shown, it will be understood that such device may be a battery of shredders to reduce the size of the materials by various successive stages, or there may be a plurality of the shredders feeding in parallel to the conveyor 12, as may be appropriate for the volume and character of materials to be processed. In any event, the shredded materials will comprise particles of varying weights and sizes within a desirable shredding range for the ultimate disposal, recycling or utility classifications and grades desired. The construction and operation of the conveyor 12 are such that it will travel at a speed which is high enough, having regard to the character of the materials to be classified, to propel the materials from the release point into and through the substantial space within the chamber 14 for ballistic separation. That is, the velocity with which the materials are propelled from the conveyor into the classification chamber is such that non-airborne materials (i.e. heavy materials relatively unaffected by air flushing separation) will generally vertically stratify by weight classifications. The heaviest such materials will travel ballistically the greatest distance from the release point, to the opposite side of the classifying chamber, while the lighter weight non-airborne materials will gravitationally drop or free fall into respective positions nearer the drop-off point. Airborne materials (i.e. those which can be separated and classified by air flushing) from so-called lights to the heaviest can cross the classification chamber for separate classification. To facilitate ballistic classification, the conveyor 12 is desirably inclined upwardly toward the release point such that the materials will be propelled in a trajectory generally upwardly and forwardly within the classifying chamber, substantially as shown by solid directional arrows. To meet variable conditions of the materials being processed having regard to such factors as character and moisture content the driving angle and speed of the conveyor 12 may be suitably adjusted.

As the generally vertically stratified classifications of non-airborne materials descend within the classifying chamber 14, they are collected in receptacles 15 along the bottom of the classifying chamber, conveniently comprising a series of upwardly opening flaring hoppers having contiguous sloping walls 17 joined with the respective adjacent wall in each instance at or along a ridge 18 which is sufficiently lower than the materials release point to accommodate the ballistic trajectories of the respective classified materials to be received in the hoppers. Desirably the fixed upper ends of the hoppers are about the same width, considered in the ballistic direction from the conveyor release point. Along the ridges 18 the hoppers may be fitted with respective pivotally adjustable blade deflector flanges 18a which can be angularly adjusted, as shown, to vary the width of hopper mouth and thereby vary the fraction of the shredded aggregate which it collects. At their lower, discharge ends, the hoppers may vary in width in accordance with the relative volume of the respective classifications of materials to be accommodated. For example, the first hopper in the series for accommodating fines and lightest non-airborne materials may be of substantially wider discharge end configuration than the hoppers next succeeding in the series up to the last hopper in the series for accommodating the heaviest of the non-airborne materials and which may be as wide or even wider than the fines hopper. The intermediate hoppers may have the discharge ends progressively narrower. This is a desirable relationship to enable use of correspondingly relatively sized means for conveying the respective classified materials from the hoppers. While suitable chutes, cyclones and the like may be employed for receiving and disposing of the materials from the hoppers, discharge belt conveyors 19 may be employed underlying the discharge ends of the hoppers and transporting the respective materials to any desired point beyond the classifier, for further processing or disposal.

In order to assist in separation of any clumps of the shredded materials and to separate airborne particles from non-airborne particles and to remove as much as practicable of dust from the classified materials, air is desirably moved as shown by open-headed arrows in flushing relation through the materials generally in the direction of projection of the materials and into the downwardly gravitating materials at suitable agitating velocity. For example, at least one forced or compressed air supply distributor or manifold 20 may be mounted across and on or at least in association with the upper portion of the first or fines hopper wall at the side from which the materials travel and over which the materials must pass as propelled from the conveyor 12. Streams of air under pressure from suitable ports or nozzles from substantially the lengths of the manifolds are directed in generally the ballistic direction, that is in a generally horizontal but desirably at least slightly upwardly angled direction to sweep through and agitate the onwardly and downwardly moving materials at least at a sufficient velocity to separate clumped materials, and drive lighter airborne materials beyond the hoppers 15, toward one or more exhaust ducts 21 located to communicate through a downwardly and rearwardly sloping backstop wall 22 at the side of the classifying chamber housing remote from the conveyor 12. Each of the hoppers may be, and as shown is, equipped with one of the air projection manifolds 20 and for the same purpose. Air under pressure from at least the distributor manifold 20 which is nearest, and, as shown, below the release point, may be driven through the descending materials at a greater velocity than from the remaining manifolds to assure initial thorough agitation and assistance in separation of the materials. On the other hand, the air projected from the distributor 20 located below the release point may be at a minor velocity so as to avoid thrusting of non-airborne fines into a subsequent classification zone, and the air projected from anyone or more of the subsequent manifolds 20 may be at an increased classifying velocity to enhance flushing, and onward movement of airborne particles, depending upon the character of the shredded materials being processed. Air may be supplied to the manifolds 20 from any suitable compressed air source such as a compressed air tank, compressor, and the like.

Where only one exhaust duct 21 is used, it is located at a sufficient height and distance from the ballistic conveyor drop-off point, so that heavy material propelled with maximum momentum from the release point cannot escape but will be guided down the sloping backstop wall 22 into the heavy material hopper. Moreoften, however, a plurality of the exhaust ducts 21 will be desirable in order to separate various gradations or materials of airborne nature. In one arrangement, as shown in FIG. 1, the backstop wall is provided with a plurality of the exhaust ducts 21 located at suitable elevations to receive the respective horizontally layered classifications of airborne materials wherein the lightest of such materials will be taken off by the uppermost exhaust duct 21 and successively heavier of such airborne materials will be taken off by the successively lower exhaust duct 21. To prevent ballistically propelled particles from entering the exhaust ducts 21, at least below the uppermost of th ducts, the lower ducts may have downwardly and inwardly sloping respective shield flanges 21a across at least the upper portions of the mouths of such ducts.

From the exhaust ducts 21 the airborne materials may be collected in any suitable manner such as in respective cyclone-type collector separators 23 which create negative pressure, i.e. suction, into the ducts 21 to enhance collection and classification of the airborne materials. Dust is removed and separated in the cyclones 23.

In reference to FIG. 2, a classification system is disclosed in which by combination simultaneous gravity and pneumatic classification heterogeneous shredded refuse materials are separated out as airborne and non-airborne, and generally horizontally stratifying of the airborne materials fractions or classifications and vertically stratifying of the non-airborne materials is effected. Collection of the classified airborne materials is in generally vertically oriented receptacles at the opposite side of the classifying chamber from the point at which the material is released into the chamber. Collection of the stratified non-airborne materials is in horizontally oriented receptacles in the bottom of the chamber. To this end, heterogeneous refuse materials are delivered through a hopper 24 to shredding means 25 discharging onto a conveyor 26 which may be supported on a vibratory mount 27 such that as it feeds the shredded material forwardly into a classifying chamber 28 within a tower-like enclosure, the materials are partially classified horizontally, by weight, the heavier materials gravitating into a lower layer on the conveyor while the lighter materials are in a superimposed layer on the heavier materials. Dirt, glass particles, stones, metal bits and like small heavy particles may be separated by sifting through a screen 29 on the conveyor. Support for the conveyor assembly may be provided by a tower frame structure 30 at the top of which the discharge end of the conveyor is located to dump the shredded materials into the upper end of the chamber 28 at one side to gravitate toward a generally downwardly and inwardly sloping side wall 31 on the frame and providing that side of the housing defining the chamber 28.

For efficient classification of airborne materials, the chamber 28 is desirably of substantial height. As the airborne shredded materials pass across the chamber they are efficiently classified in successive horizontal classifying zones or layers, the number depending upon the general character of the materials to be classified. By way of example, there may be four such zones, the highest being that for the lightest weight materials, such as film plastics and fines, and the next vertically succeeding classifying zones being for progressively heavier but airborne materials. While the non-airborne materials are permitted to descend gravitationally to the bottom of the chamber 28, as indicated by the solid directional arrows, the lighter airborne materials are, according to their respective weights and particle volume, progressively separated from the heavier materials and removed from the chamber.

Means for establishing the vertically successive generally horizontal strata in classifications of the airborne materials desirably comprise classifying air streams driven in generally the horizontal direction of delivery of the materials into the classifying chamber 28 and into the downwardly gravitating materials at a velocity to effect selective separation of the materials into airborne classifications by weight while in free fall in the chamber. The air streams are produced by projecting the same from respective vertically spaced horizontally elongated distributors or manifolds 32 located on or in association with and parallel to the wall 31. Each of the manifolds 32 is suitably ported to provide a generally horizontal classification strata air stream transversely across the chamber at about the level of the respective manifold. While the manifold may have a series of horizontally spaced nozzles, orifices or ports 33 (FIG. 3), a single slit port extending throughout substantially the length of the manifold and appropriately oriented may be used if preferred. The ports are desirably directed to project the air streams therefrom in a generally inward and slightly upward direction, substantially as shown by open-headed arrows in FIG. 2 so that as the shredded materials drop through the generally inward and upwardly oblique sheets of air, the lightest, more flocculent elements of the shredded materials will be blown from the gravitating materials by the air stream sheet nearest the materials drop-off point. Successive grades of classifications of the airborne materials, by weight, will be separated from the downwardly descending or gravitating materials in successive classifying layers or zones, until the airborne materials are effectively separated from the materials which are too heavy to be airborne and which gravitate to the bottom of the chamber. Air may be supplied to the distributor manifolds 32 in any desired manner, such as through respective conduits 34 leading thereto and receiving air under desirable pressure from suitable means such as compressed air tank, a single large capacity fan blower, or individual blowers 35 which may be of the medium pressure type, providing relatively large volume and at a suitable pressure for the particular classification intended in respect to the distributor in question. By their generally horizontal air blowing direction the manifolds are self-cleaning with respect to materials dropping thereon.

Means may be provided for adjusting the distributor manifolds 32 to attain the most efficient angle of attack of the air streams in respect to the particular classifying zone with which associated. One such means comprises connecting the distributors 32 by means of a tubular inlet 37 to the associated conduit 34 by a flexible connection 38, so that the member 32 in each instance can be adjusted about its respective axis to provide the highest efficiency attitude of the air projection ports 33. The manifolds may be mounted pivotally on end trunnions 32a for this purpose. The specific description of the manifold 32 in FIG. 3 may be considered applicable to FIG. 1 in respect to the manifolds 20 as well as to FIG. 2.

Collection of the classified airborne materials is effected in a battery of respective receptacles 39 located at the opposite side of the chamber 28 from the materials drop-off point and aligned with the manifolds 32 in a manner to receive the classified materials. For this purpose, the respective receptacles 39 are spaced at the respective appropriate elevation for each classification, and at varying spaced distances from the release or drop-off point, such that the lightest weight materials or fines are directed by the highest air stream zone blanket into the uppermost of the receptacles 39, and successively heavier classifications of the materials are directed into respective ones of the receptacles 39 spaced thereunder and of course farther spaced from the drop-off point, insofar as the airborne classified materials are concerned, indicated by relatively light line open-headed directional arrows.

To assist the main classifying air stream zone stratum as produced by means of the primary distributor manifolds 32, supplemental air streams may be directed generally in the direction of desired air stream flow for each, or any selected classification zone, by means of one or more, and preferably a horizontal, spaced series, of supplemental distributor manifolds 40, located at suitable spaced intervals inwardly from the wall 31. These manifolds 40 may be similar to and mounted adjustably like the manifolds 32. Thereby, in effect, respective substrata of air may be provided for the affected zones, but at least the principal air streams or blankets from the manifolds 32 will be reinforced.

In addition, means are desirably provided for mechanically agitating the materials as they drop in free fall relation in the chamber 28, to separate and disperse the materials and enhance efficient simultaneous gravitational and air classification. To this end, beater or flipper plates 41 are mounted on respective horizontal axes 42 on or in association with and parallel to the wall 31, at selected vertically spaced elevations below at least some of the manifolds 32 and operated to swing about their pivots in a generally up and down manner within a suitable arc, but always remaining in generally downwardly and inwardly oblique respective planes. Means are provided for operating the flipper plates 41, desirably in unison, although each of the plates may be independently operated if desired for relative cyclical movement relative to the other plates. In a desirable arrangement, each of the plates has one or more rigidly carried outwardly extending rocker arms 43 pivotally connected to a respective driving link 44 attached at its lower end to a respective pitman 45 connected to a driving crank 47 (FIGS. 2 and 4) which may be driven in any suitable fashion as by means of an endless flexible driving element 48 such as an endless belt trained over a pulley 49 and driven by an electrical motor 50. Through this arrangement, the flipper plates 41 are rocked through their respective operating arcs at any desired, and preferably fairly rapid rate of speed such that as the materials drop, at least the heavier materials will be repeatedly mechanically agitated to facilitate separation and classification.

Means are provided for adjusting the angle of the wall 31. For this purpose the entire wall 31 can be adjusted on a pivot bearing 31a by adjustable support arm means 31b, to adjust for seasonal differences in refuse being classified, as when there is much heavy wet grass, or a large volume of dry leaves, or much wrapping paper, etc.

Agitation of the free falling materials in the chamber 28 by means of the flipper plates is not only useful in enhancing air separation and classification of the lighter materials, but also facilitates classification of the heavier materials. Thereby, the materials which are not separated by the air streams, are nevertheless generally classified as to heaviest and lighter, since the heavier materials as they strike the flipper plates 41 are propelled farther from the wall 31 than the lighter of the non-airborne materials. As a result, as the non-airborne classified materials drop to the bottom of the chamber 28, the different classifications thereof are received in respective receptacles 51, of which there may be as many as desired, opening upwardly and with the receptacles receiving the lighter of the gravity classified materials being nearest the wall 31 and the receptacle 51 for the heaviest material being the farthest from such wall. A generally upright flange divider, adjustable similarly as the adjustable flanges 18a, 52 may be located between each adjacent bottom receptacle 51. While the materials from these receptacles may be removed in any suitable fashion, they may drop onto respective endless conveyors 53 for transportation from the classifying chamber 28.

For receiving the air classified materials, the vertically spaced receptacles 39 may be in the form of respective receiving throats 54 leading to respective cyclone collectors 55, each of which is connected by means of a suction duct 56 to an exhaust fan 57 driven by a respective motor 58. From the cyclones 55, the classified materials may be dishcarged to any suitable utility apparatus or transportation device. Extending downwardly and obliquely inwardly from the entrance into each of the throats 54 is desirably a deflector plate 59 whereby materials gravitationally escaping the particular classification for the respective receptacle will be guided generally downwardly and inwardly to join the next classification, and so on until if any material is too heavy for any particular air classification, it will eventually descend to the bottom classification zone. Dust will be efficiently driven from the classifying chamber 28 by the air streams from the manifolds 32 as well as by suction into the cyclones 54, and will be separated from the respective classifications of materials in the cyclones 54 and generally in the topmost cyclone, to exhaust from the respective fans 57 to one or more suitable dust collectors.

In the classification of municipal waste, at least certain of the classified fractions of the materials are economically valuable, such as metals, glass and paper. While, after classification in accordance with the present invention, it may be desirable to grade or further separate the recovered materials in any classification for efficient salvaging, nevertheless, the general classifications attained are of substantial advantage and value in promoting recycling of useful materials. For example, a large percentage of municipal waste in most geographical areas consists of various grades of paper which even in shredded condition reasonably retain their different mass characteristics relative to each such grade and relative to other kinds of materials in the shredded bulk as delivered by the conveyor into the classification chamber. Thus, in the classification system according to FIG. 1 after the first hopper into which the lightest, non-airborne paper will be received, the next hopper may receive heavier paper, cardboard and rags, the next succeeding hopper may receive plastic containers, aluminum and light glass particles, and the hopper immediately thereafter may receive heavier glass, rock, tin cans and heavy metal particles. Materials of greatest specific gravity and mass, such as tramp metal and rock, will be received in the final hopper or hoppers. Airborne materials such as fines, film plastic, paper, etc., will be collected in the cyclones. Similarly, in the arrangement of FIG. 2 airborne fines and film plastic and other materials of similar lowest specific gravity will be received in the topmost cyclone receptacle, light paper in the next lower cyclone receptacle, medium paper in the succeeding lower cyclone receptacle and heaviest paper and light rags in the lowest cyclone receptacle, while the different specific gravity non-airborne materials, heavier than the paper and other airborne materials will classify in the bottom conveyor receptacles.

According to the invention as represented in the system of FIG. 5, shredded waste materials are serially classified by removing the heaviest airborne materials first and then successively removing progressively lighter materials. To this end, initial non-airborne material removal is adapted to be effected in a classification chamber 60 wherein the materials may be introduced and mechanically and pneumatically agitated and separated, in a manner similar to the arrangement in FIG. 2 wherein the materials are dropped toward mechanical beaters or flippers and air is forced through the descending and agitated material, not only to effect further separation but to remove all but the heaviest, non-airborne, materials for cyclone classification. The non-airborne materials are, similarly as in FIG. 2, collected in receptacles at the bottom of the chamber 60, including receiving and transporting conveyors 61. All of the air-borne materials are pneumatically propelled from the chamber 60 through an exhaust passage 62 into a first cyclone separator receptacle 63 which may be the largest of a generally horizontally in-line series and in which the heaviest of the materials received therein will be separated from lighter materials and discharged from the bottom of the cyclone into a suitable receiving device such as a take-off conveyor 64. The remaining materials then pass from the top of the cyclone 63 through a duct 65 to a second cyclone separator receptacle 67 which is controlled to remove a second increment or fraction of the lighter materials and discharge to a conveyor 68. From the cyclone 67 the remaining materials pass by way of a duct 69 to a third cyclone separator 70 which removes a third fraction of the materials, deposits the same in a take-off conveyor 71, and moves the remaining materials through a duct 72 into a next succeeding cyclone separator 73 which will remove, for example, the remaining salvage increment of the shredded materials and discharge to receiving means such as a take-off belt conveyor 74. From the final cyclone 73 in the series, dust, fines, light film plastic, and the like, are exhausted through a duct 75 to a suitable dust collector 77. There may be, of course, as many of the cyclone classifiers in the series as there are grades of materials to be classified, especially for salvage. For example, where paper is to be salvaged, the first cyclone classifier 63 may be adapted to separate heavy paper including cardboard and paperboard. The next cyclone classifier 67 may be adjusted to remove medium paper. The next succeeding cyclone classifier 70 may be adjusted to remove lighter paper, and the last cyclone 73 may be adjusted to remove the lightest grade of paper. This same arrangement of cyclones may be used with the classifying chamber 14 of FIG. 1 instead of the vertical arrangement of cyclones there shown.

In order to enable inspection during operation, any suitable portholes may be provided at appropriate locations in the walls of the respective housings for the classification chambers, and suitable lighting provided in the chambers. Such observation will enable determining of the effect of adjustments in volume, angle and speed of air that may be effected in any part of the system for attaining optimum results. Municipal refuse processing presents special problems in this regard due to seasonal, geographic, area and weather variations in the character of the refuse to be classified. For example, in one location predominantly dry materials may be present in the refuse and in another location in that area or in another area predominantly moist materials may be present. In other areas, the volume of one or another kind of material may vary from time-to-time or season-to-season. Dry materials may be predominant in certain seasons of the year and wet materials in other seasons of the year. For example, dry or wet leaves may be present in large quantity in the fall while grass clippings and shrubbery trimmings may be present in the spring and summer months, while during the holiday seasons exceptionally large quantities of wrapping paper will be encountered. In any area, after a severe rain storm, all airborne materials are heavier and require more air for classification, which can be adjusted for. The same basic system can be adjusted for all these geographical and area differences.

If materials are usually or often moist, provision may be made for heating the flushing air to give a drying effect and to facilitate classification and subsequent processing.

It will thus be apparent that the present invention provides efficient, high volume waste material classification, and more particularly for municipal refuse. The systems are versatile and adjustable to accommodate geographic and seasonal variations in the character of the refuse or municipal wastes to be classified. Speed and volume as well as angle of projection in delivery of shredded materials into the classification chamber may be varied. The number of classifications in any system may be varied. Mechanical agitation is adapted to be varied by the number, size, operating angle, speed and relative disposition of the mechanical agitators. The angle of the guiding wall surfaces in the classification chamber along which the materials descend may be varied. Pneumatic velocity, pressures, volume angles of impingement, numbers of jets or manifolds, air temperature, and the like, may all be varied to suit requirements. Within theses numerous adaptabilities, the principles of the classification systems remain the same.

It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

In all embodiments of the invention an important feature is the providing of adequate free fall space from tower drop-off or trajectory point to facilitate adequate dispersion of the materials to be classified, so that the several classification systems will operate efficiently, simultaneously, gravitationally and pneumatically.

Another important feature resides in providing a combination of both positive and negative air pressures in the systems, operating simultaneously to provide a large volume, efficient classification and removal result.