BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method and apparatus for separating and breaking up municipal refuse. More particularly, the invention relates to a method and apparatus for breaking up municipal refuse of the type typically packed in plastic garbage bags. It is necessary that metals, glass, and other non-combustibles be separated from paper, plastic, and other combustible materials for recycling. The combustible materials may be recycled or further processed for fuel uses, etc. All of the above is done in a mechanical unit capable of being constructed as a portable trailer mounted device for transport from one site to another, all without requiring residents of the municipality to separate items at curbside.

Description of the Prior Art

Many recent attempts at arriving at a satisfactory method and apparatus for waste separation are known in the art. The U.S. Patent Nos. 3,618,866 to Robinson, 3,749,324 to Hyde, 3,826,437 to Warren, Jr., et. al., 3,876,157 to Maclntire et. al., 4,009,838 to Tashman, 4,011,999 to Glaeser and 4,081,143 to Johnson et. al., all show separator apparatus which were thought to provide satisfactory solutions to the problem of how to separate municipal waste.

The U.S. Patent Nos. 4,778,116 and 4,867,866 to Mayberry disclose a method and apparatus which have some features in common with the present invention and are perhaps the closest prior art known by the inventors. However, the

present invention is much improved over any prior art known to the inventors.

It is well known that municipal waste must properly be processed and disposed of so that it does not create health risks to the community, and also so that natural resources are conserved. In many communities, attempts at recycling by having residents sort the municipal waste by the curbside have started with great enthusiasm, and then faded by the wayside as the residents found the sorting process too burdensome to continue. Thus, the search continued for a way to sort municipal waste at the processing site, rather than at curbside. This involves the problem of how to separate the different types of municipal wastes, such as non-combustible materials, including glass, metal grit, etc. and combustible materials such as paper, plastic, and so forth. These are all found wrapped in the typical plastic garbage bag at curbside.

Generally, the process of separating municipal wastes was performed by mechanical means, such as mechanically separating combustible materials from glass, metal and other non-combustible materials. Article or piece size would first be reduced by using hammer mills or shredders, and then ferrous materials would be removed with magnetic separators and the like.

Also, typically in the sorting process, vibrating screen conveyors are used for separating particles of various sizes. However, such vibrating conveyors often become clogged. Therefore, there is a need in the prior art for an alternative to the vibrating screen conveyor for doing the separating operation.

SUMMARY OF THE PRESENT INVENTION

In order to solve the problems present in the prior art, it .was necessary to arrive at a new approach to the problem of separating combustible from non-combustible material. It was not until it was realized that non-combustible materials are generally brittle and heavy while combustible materials are generally much lighter and not brittle that a satisfactory method and apparatus was developed. In accordance with the present invention, a hammer mill is used with a first or small item pitching unit followed by a second or large item pitching unit. An air current or updraft is continuously forced upward through these pitching units. The hammer mill is followed by a bag shredder will first pulverize all generally brittle non-combustible materials. Since these are generally heavier than the combustible materials, they are then passed through two separator units to separate the non-combustible materials, which fall through the pitching units and are carried off by conveyors, from the generally lighter combustible items which have been shredded into pieces of a size that are easily carried by the air updraft past the pitching units for further operations thereon.

Thus, one of the objects of the present invention is to provide a new and improved method and apparatus for separating municipal waste materials based on the difference in properties between combustible and non-combustible municipal waste.

A further object of the present invention is to provide a portable apparatus for the practice of the method of the present invention.

Another object of the present invention is to provide an improved apparatus for separating municipal wastes which eliminates the need for screen conveyors.

A still further object of the present invention is to make improved use of air pressure or air current updraft to perform the dual functions of aiding the separation of glass and small items from the typical mix of municipal waste, as well as separating the combustible materials from the non-combustible materials.

Further objects and advantages of the present invention will become apparent from reference to the drawings appended hereto, wherein like reference numerals in the several views refer to identical parts.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a construction embodying the present invention.

Figure 2 is a more detailed, elevational view of the apparatus shown in Figure 1.

Figure 3 is a block diagram of a construction embodying an apparatus for practicing the method of the present invention.

Figure 4A is a diagrammatic view of a construction embodying the present invention.

Figure 4B is a largely schematic view of an air supply system for the present invention.

It is to be understood that the present invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments, and of being practiced or carried out in various ways within the scope of the claims. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description, and not of limitation.

τraTATT.1i_n DESCRIPTION OF THE PREFERRED EMBODIMENT

An improved portable refuse separator embodying the present invention, generally designated by the numeral 20, is shown in block diagram form in Figure 3. Municipal wastes are typically placed in plastic garbage bags by residents of a municipality, and are then collected by garbage trucks from curbside or taken from dumpsters, etc. This waste is fed into the feeder 21. From the feeder 21, the waste is fed into a shredder or hammer mill 22. The shredder or hammer mill 22 is known to act differently on non-combustible, sometimes brittle, wastes, than it does on combustible waste such as paper or plastic. Non-combustible waste such as glass or metal is susceptible to shattering or substantial crushing upon receiving a hammer type blow, while combustible waste, such as paper or plastic items, which are normally only a few thousandths of an inch thick, are not susceptible to shattering or crushing.

It is known that the non-combustibles passing through a shredder or hammer mill can be acted upon so that perhaps up to 95% of the non-combustible pieces are of a predetermined size, in which no dimension is greater than a selected predetermined dimension, such as approximately 1-1/2 inches. Using the same equipment under proper conditions, up to about 95% of the combustible materials, such as paper and

plastic products, will be of a size in which at least some dimensions are greater than the selected dimension. For example, some pieces of paper would come through the shredder or hammer mill less than 1-1/2 inches wide, but would likely be more than an 1—1/2 inches long. This property of the hammer mill or shredder 22 is used for further processing.

Before such further processing takes place, the refuse will also, preferably, go through a bag shredder, connected to or adjacent to the hammer mill, to insure that the plastic garbage bags in which the refuse comes wrapped are shredded into long narrow pieces. As is well known in the art, the bag shredder 23 comprises a plurality of stationary or swinging knives and/or hammers.

The waste next goes into a small pitching unit 24, connected to or adjacent to the bag shredder 23, having openings, to be described in more detail hereinafter, of approximately 1-1/2 inches in width. The pitching units are somewhat similar to units which have been utilized in threshing units. The pitching units have a series of parallel longitudinally extending bars 60 which extend upward from the surface of the unit at an angle. Although only a portion of the bars are shown, it should be understood that bar 60 extend throughout the entire length of the pitching unit 24. Each of the longitudinally-spaced bars have a lateral or transverse bar 63 which reciprocates with the longitudinally extending bars 60 and force the refuse forwardly. Anything which is wider than the distance between the longitudinally-spaced bars 60 will be forced or pitched forward from one set of longitudinal bars to another. Anything that is smaller than 1-1/2 inches width, and heavier than can be lifted by the air stream to be described, will fall through the pitching unit to a conveyor, as will be more fully described.

It is preferred that the small pitching unit 24 has a spacing of approximately 1-1/2 inches between bars, and that toward the end of the pitching unit an air stream, air current, or air updraft is provided by an air supply means, such as provided by blower 26, or the like. Air passing through air duct 25, after exiting blower 26, will be directed upwardly and through small pitching unit 24 near a downstream the end thereof, and upwardly and through large pitching unit 27 over a substantial portion of its length. It is preferred that the air flow be in a closed path or circuit to prevent possible pollution of the outside air.

Most all of the non-combustible waste will fall through the small pitching unit 24 and proceed, by means to be described, to the connected or adjacent large pitching unit 27. Large pitching unit 27 is similar in construction to small pitching unit 24, but has the longitudinally-spaced bars 62 spaced at a width of approximately 5 inches. Transverse bars 61 perform the same function as bars 63. This spacing is sufficiently large to cause virtually any heavy, non-combustible objects which are left to fall through the pitching unit and travel to a magnetic separator 28, connected to or adjacent the large pitching unit 27, for further processing. The combustible materials, such as shredded paper bags and plastic bags and the like, do not fall through the large pitching unit, but are caught by the previously described air updraft travelling through the large pitching unit 27. It is preferred that small pitching unit 24 be operated offset from large pitching unit 27. That is as small pitching unit 24 is driven forwardly, large pitching unit 27 is pulled rearwardly. The two alternate this offset forward and back movement.

The shredded plastic and paper pieces travel in the air stream to a traveling screen 29, where they are forced

against the screen while the air continues to the blower 26. The brush or deragger 30 knocks these particles off the traveling screen and causes them to fall into the discharge area 31.

Since it.is preferred that a closed loop air system be utilized, it is necessary ^* to keep the air stream flowing with clean air. As paper and plastic in the air would eventually block or reduce the flow of air and retard the operation, the paper and plastic must be removed from the air. The screen 29 is driven to run over four rollers and travels at a slow rate of speed. As one example, the screen may travel at twenty or thirty feet per minute. The screen comes in contact with a rotating brush 30 which cleans plastic paper or any other item from the screen 29 and allows it to fall onto conveyor 44.

Figure 4B is a largely schematic view of the air flow system for this invention. As shown, travelling screen 29 surrounds a chamber 53 through which the air will flow into ducts 52. Ducts 52 supply air to fans 54 which in turn supply the air to downwardly extending ducts 56. Ducts 56 are somewhat equivalent to the duct 25 as shown schematically in the Figure 3. At the bottom of ducts 56, the air is allowed to flow laterally inwardly into space 58. Space 58 is preferably between the adjacent ends of conveyors 33 and 36. The air flow moves through the direction shown in broken line in Figure 4 such that it passes through a downstream end of small pitching unit 24, and flows through substantially the entirety of large pitching unit 27. It also pulls paper and plastic that may be falling off of conveyor 33 downwardly, towards conveyor 34.

The portable separator 20 is shown in more detail in Figures 1, 2, 4A and 4B. As previously described, the municipal waste is dumped onto the feeder 21, which may be any suitable

apparatus which propels the waste materials at a desired rate, and may be such as a vibrating table, or conveyor, and the like. The refuse is passed into a pair of shredders or hammer mills 22 which are, preferably, rotating in the same direction. They are suspended below the bag shredder 23. The power for rotation of the hammer mills, and driving of the apparatus is provided by the diesel or gasoline engine 32. The engine 32 may directly drive the apparatus, and/or power a generator (not shown) which will produce electrical current for driving the apparatus by way of electric motors. A combination of both drive systems may also be used, depending on the application. The unit may also be powered electrically from an outside source if desired.

The hammer mill or shredder 22 will shatter or compress the non-combustible material such as glass, metal, stones, grit or the like, where most of it will immediately fall through the narrowly-spaced bars 24A provided in a first portion of the first or small pitching unit 24, while the combustible materials will be lifted into the airstream or air current provided by the blower 26. The non-combustible materials will fall onto a first or glass or small item conveyor 33. Any non-combustible material which does not fall through the first or small pitching unit 24 will be carried forward to the second or large pitching unit 27, together with any combustible materials not lifted into the airstream or updraft. In Figure 4A, the direction of falling waste particles is shown by solid airs, while air flow is shown by broken lines.

These items will travel onto the second or large pitching unit 27 where, because of the spacing of the lateral bars, virtually all of the remaining non-combustible material will fall onto second or large item conveyor 36, and a second opportunity for the combustible material to be lifted into the

airstream is provided. The large item conveyor has a magnetic pulley 37 which will pick up ferrous metals from the small item conveyor before the remaining items are sent to the small item discharge conveyor 34. The generally lighter combustible materials, such as paper or plastic, are all caught in the updraft, and will be lifted upward to travel toward the traveling screen 29.

The items on the second or large item conveyor 36, including the ferrous metal from the first or small item conveyor 33, next come into contact with the magnetic separator 28 which has a conveyor belt 38 which passes over rollers 39. The belt 38 passes over magnet 40 during a portion of its travel. The magnet is placed sufficiently close to the end of the second or large item conveyor 36 so that nonferrous materials pass on to the nonferrous material conveyor 41. The ferrous materials stick to the belt 38 while it travels past magnet 40, with any of the ferrous materials attached thereto. As soon as the belt 38 passes the magnet 40, the ferrous materials drop into the ferrous material conveyor 42.

Arranged past the conveyor belt 38 are a heavy combustibles discharge belt 43 and a light combustibles discharge belt 44. The air velocity through the air system is carefully chosen so that all combustible materials travel over the conveyor belt 38. The air velocity is not so great as to cause the heavier combustible items to be attracted to the traveling screen 29. Because they are heavier, the heavy combustible items will fall by gravity first onto the heavy combustibles discharge belt 44. The lighter of the combustible materials will travel further, and will fall onto the light combustibles discharge belt 43. The combustible materials which are extremely light will continue in the air stream until they are forced against the travelling screen 29, at which time the

brush or deragger 30 will remove them from the screen and also cause them to fall to the light combustibles discharge belt 44. The heavy combustibles discharge belt 43 is optional, and a single belt may be substituted for the dual belts shown. In some applications, a settling chamber 46 may be placed under traveling belt 29 to aid in gathering the lightest combustible materials.

Separation of combustible waste materials from non-combustible waste materials by the method of the present invention also allows the possibility of burning the combustible waste materials, thus easing the burden on landfill operators in complying with certain government regulations. It also raises the possibility of producing refuse derived fuel, which may have up to half the heating value of coal, and can be substituted for or co-fired with coal or other fossil fuels such as oil and natural gas.

Also, it should be understood that the present invention may be completely portable, and may take many forms, such as being a portable trailer mounted device transferrable from one site to another, or a modular device for semi-permanent placement in a municipal waste facility. Permanent installations are equally satisfactory.

Thus, by developing a new approach to separating the combustible and non-combustible materials found in municipal waste, and improved method and apparatus which solves long standing problems in the present art is provided.