US3888351A

US3888351A - Automatic refuse reclamation system

Info

Publication number: US3888351A
Authority: US
Inventors: David G Wilson
Original assignee: Massachusetts Institute of Technology
Current assignee: Massachusetts Institute of Technology
Priority date: 1974-05-31
Filing date: 1974-05-31
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10

Abstract

An automatic refuse-reclamation system wherein unprocessed municipal waste is initially separated into five distinct streams: light paper, light plastics, magnetic materials, large items and fines. The system employs many small carts that receive the large items individually, permit identification of the large items and deposite thereof in appropriate receptacles. The fines are separated from one another in a vortex classifier.

Description

United States Patent Wilson AUTOMATIC REFUSE RECLAMATION SYSTEM June 10, 1975 Smith et al 73/12 Watner 4. 198/38 lO/l972 4/1973 [75] Inventor: David G. Wilson, Cambridge, Mass. Primary Examiner koben B Reeves [73] Assignee: Massachusetts Institute of Assisi!!!" Examiner-H Gram Skaggs Technology, Cambridge, Mass Attorney, Agent, or Firm-Arthur A. Smith, JIZ;

R I S I Filed: y 1974 ober Shaw, Martin M an a [211 App]. No.: 475,488 [57] ABSTRACT An automatic refuse-reclamation system wherein un- 52 us. (:1. 209/75; 198/38; 214 11 Processed municipal waste is initially Separated into 51 Int. Cl. 801d 37/02 five distinct streams light P p light Plastics. g- [58] Field of Search 209/72-75, materials, large items and fines- The System 09 5 13; 193 3 214 11 ploys many small carts that receive the large items in dividually, permit identification of the large items and [56] References Cited deposite thereof in appropriate receptacles. The fines UNITED STATES PATENTS are separated from one another in a vortex classifier.

3,747,555 7/1973 Sentenuria et al 209/1115 10 Claims, 18 Drawing Figures IOI 1 RAW REFUSE WATER JET 6 BAG SLITTER METAL DETECTOR TRAVELLING-MESH IMPACT mn-sucnon SCREEN 'gfigg ELER METER 2A NFRA RED TRAVERSE COMPUTER 2 BELT E v 17 r it 4 ELECTROMAGNET u II} 533; 1 7 2C TWO-DECK wannrmc SCREE "wk m 1 s; ART READERS 28 Q & UNLOADERS PLASTIC H M 7 18 20A 28 t L FINES r uumwmc SHEET PAPER 1-. I: OBJECT I02 2 FERROUS MATLS 9 SENSOR HOPPER? 29 cam? MICELERATOR PATENTEUJUH 10 ms MAGNETIC SEPARATOR MAGNETIC MATERIALS COMMINUTER TO VORTEX CLASSI Fl ER lOl SHEET 1 FEED HOPPER LOOSE PAPER E Q AND PLASTICS 4 SEPARATOR PLASTIC PAPER FILM SHEETS II T f cARTs 3 PFINES ll'Qll 8 LARGE- f ITEMS VORTEX OUT CLASSIFIER METAL INFRARED IMPACT DETECTOR SENSOR ACCELEROMETER COMPUTER l7 CART f CODER PATENTEDJUH 10 38 I5 208 q I9A L/ l 1\ /2 IIA l3 l4 l5 -4 7 7 7 METAL INFRARED IMPACT DETECTOR] SENSOR ACCELEROMETER 7 3 SPECIAL-PURPOSE d COMPUTER l6 PATENTEDJUN 1 0 I975 SHEET FIG. 6A

FIG. 6B

PATENTEDJUH 10 I975 SHEET FIG.

24 FIG.

FIG. 714

ELECTRIC 4 ,9 D R/ E 7} 5 #1 -56 DRIVE critg ELECTRIC MOTOR SHEET PATENTEDJUH 10 I975 FIG. 8A

CART A cART A FIG. 86

cARTA CART 8 CART 8 PATENTEDJUH 10 I975 SHEET 1 H/sec SENSOR IOVE 7 B A +5H/sec? OBJECT SENSOR FIG. .9

CART 29 ACCELERATOR 1 AUTOMATIC REFUSE RECLAMATION SYSTEM The invention was made in the course ofa grant from the Environmental Protection Agency, Office of Solid Waste Management, an agency of the United States Government.

The present invention relates to refuse-reclamation systems that accept unprocessed municipal waste and divide that waste into categories automatically.

There accompanies herewith the Masters thesis of John Murray Malarkey, hereby incorporated by reference herein. The work upon which the thesis is based was done at MIT. under the supervision of the present inventor. The thesis contains, among other things, explanations of prior-art approaches to refuse-relamation systems, mathematical treatment of aspects of the present system. detailed explanation of an embodiment of the present system, etc., much of which is not repeated here. The thesis was deposited in the M.I.T. library system on or about July 10, 1973.

Until recently the most serious obstacle faced by municipalities with regard to solid-waste recovery was the expense, difficulty and undesirable nature of handsorting. Two approaches exist as solutions to this problem: (l) promoting segregation of wastes at their source (in the home); and (2) developing less expensive and more efficient methods of mechanical sorting. If the prime generator of municipal waste, the householder, could be persuaded to separate his/her wastes at home, the problems of sorting and decontamination would be greatly reduced because most contamination occurs when valuable items are mixed with undesirable materials in common containers. However, it is realized that less than full cooperation can be expected from householders so that some central means for sorting is necessary if efficient large-scale recycling is to be achieved.

A number of investigations have been undertaken to determine the composition and quantity of solid wastes in urban areas. Samples indicate that 40-50% of resi dential and/or municipal solid wastes are in the form of paper products, about 9% are metals, and 8% are glass. These materials, over 60% by weight, or municipal refuse all have present potential markets in the recycling industry.

All indications are, from a comparison of available data, that a good proportion of the incoming refuse in the form of large relatively homogeneous recyclable items, e.g., tin cans, unbroken bottles, bundles of newspapers, and paper containers, which can be salvaged for recycling without further processing. This last premise forms the basis for the theory behind the pres ent approach to handling the sorting problem. It is felt that sufficient savings can be achieved by removing all large homogeneous items before further size reduction to justify the cost of the automatic sorting equipment hereinafter discussed.

A further economic as well as practical advantage of the present system is its flexibility. Since virtually all large items of refuse passing through the plant will be automatically identified, there is the capability of choosing which particular materials have enough value in the then existing market to justify their recovery. The plant is not constrained to salvaging only paper, metals, and glass, though at present those seem to have the best potential for recycling.

Accordingly, a principal object of the present invention is to provide a refuse-reclamation system wherein size reduction of the incoming trash is minimized.

A further object is to provide a system wherein large homogeneous recyclable items are salvaged for recycling without further processing.

These and still further objects are evident in the discussion that follows.

The objects of the invention are attained by a refuseseparation system that is operable to separate individual large items from the mass of raw refuse introduced to the system. lt includes pre-sorter means that includes means for mechanically agitating the refuse to break up clumps, means to divide fines in the refuse from the large items therein, means to remove loose paper and plastic therefrom, and preferably, means to remove magnetic particles. A plurality of carts, each being the leading cart of a queue of carts that travel on a closedloop track, is positioned to receive the individual large items from the pre-sorter means. Acceleration means is provided to propel each leading cart down the track and to accelerate the next cart in the queue into position. An object-detector acts to detect entry of a large item into each leading cart and is connected to actuate the acceleration means for that cart, propulsion means being provided to move each accelerated cart around its closed-loop track. There is uncoupling means to disconnect the propulsion means when a cart encounters another cart in a queue of carts. Sensors act to receive signature-type messages from each individual large item and to supply signals indicative of a plurality of characteristics of the individual large item present in each cart. The sensors are connected to means for analyzing the signals to provide an indication of the character of the individual large item sensed. Means is included for removing the individual large items from each cart at a location determined by the characteristics of the item as indicated by the signals and interpreted by the means for analyzing.

The invention is hereinafter discussed with reference to the accompanying drawing in which:

P10. 1 is a flow diagram of a system embodying the present inventive concepts and includes, among other things, mechanisms for separating out paper, plastics, magnetic materials and fines to leave large items that are received by individual carts;

FIG. 2 is a perspective view of the system, somewhat diagrammatic in form and with many details omitted;

FIG. 3 shows a portion of the system of FIGS. 1 and 2 and, in particular, shows a front-elevation view of a diagrammatic representation of a cart with the front endpiece of the cart removed to show the interior thereof;

FIG. 4 is a diagrammatic representation of a part of said system;

FIGS. 5A, SB and 5C show a queue of the carts and an accelerating mechanism for separating the leading cart of the queue from the other carts, once the leading cart has received a single large item;

FIG. 6A is a plan view, partially cutaway, of a cart similar to that shown in FIG. 3 and is intended to show a mechanism to permit removal of large items from the cart;

FIG. 6B is a view taken upon the line 6B-6B in FIG. 6A, looking in the direction of the arrows;

FIGS. 7A, 7B and 7C show a mechanism on each cart to engage a pin of a cog chain to drive the cart around the closed-loop track of the system;

FIGS. 8A. 8B and 8C show a latching mechanism to permit the securing together of a plurality of the carts at the loading region of the system;

FIG. 9 shows a portion of the system of FIGS. 1 and 2 with a number of elements added thereto;

FIG. 10 is a side-elevation view. schematic in form. of a mechanism for removing loose paper and plastic film from the raw refuse introduced to the system; and

FIG. 11 is a side-elevation, schematic in form, view of a mechanism for removing magnetic particles from the refuse.

A brief, overall description of the invention is now given with reference to FIGS. 1 and 2 wherein a refuse system embodying the present concepts is shown at 101. The system I01 includes a feed hopper l to receive raw refuse (i.e., municipal trash) after such things as bed springs, stoves, engine blocks and the like have been removed therefrom. The refuse is delivered to a pre sorter 5 that comprises a two-deck vibrating screen 2, a travellingmesh, air-suction screen 4 and a magnetized-belt system 3. As is hereinafter discussed in greater detail, the vibrating screen 2 acts to agitate the refuse, mechanically to break up clumps, and it acts, as well, to divide fines in the refuse from the large items therein. The vibrating screen 2 is inclined from its upper or receiving end 2A downward to its lower or discharge end 28 in FIG. 2. The vibrating screen 2 consists ofa large-mesh upper screen 2C and a small-mesh lower screen 2D. The refuse drops upon the upper screen 2C and passes under a very-highpressure water jet (or jets) from a waterjet bag slitter 6 in FIG. 2, As the refuse items bounce along the vibrating screen 2C, loose paper and plastic are removed therefrom by the air-suction means 4 and magnetic items by the magnet ized-belt system 3.

As the refuse moves toward the end 28, smaller items pass through the large-mesh screen 2C to the lower screen 2D. Fines pass through the lower screen 2D and are delivered to a vortex separator 8 (see US. Pat. No. 3,739,9l0, Wilson) in FIG. 1, through a chute 7 in FIG. 2. Large items are delivered to carts designated 11 in FIG. I and 11A and 118 in FIG. 2, through chutes I0 and 9, respectively, in FIG. 2. The cart system, which is an important part of this invention, is discussed in detail in the next few paragraphs.

By way of preliminary explanation, the cart system is designed so that when the carts 11A and the carts [18 leave the chute area, each contains one large item only. The term large item" is intended to denote individual items such as, for example, a can, a bottle, a telephone book, a pan, etc. A large item can be relatively homogeneous in structure (e.g., a telephone book) or it can be heterogeneous. To be valuable, the sorted product must be relatively pure. Thus, for example, an un painted aluminum can is pure but an aluminum utensil with, say, a plastic or wood handle is not. As the carts move from the chute area, in the direction of the arrow numbered 102, toward unloading hoppers 12, they pass a plurality of sensors that comprise at least a metal detector 13, an infrared sensor 14 (see United States Pat. No. 3,747,755. Senturia et al.) and an impact accelerometer 15 (see U.S. Pat. No. 3,788,466 and 3,759,085, Wilson et al.) which, in combination, act to characterize the large itiem in each cart. Messages from the sensors are connected to a special-purpose computer 16 whose output is connected to a cart coder 17 which brands each cart. The carts thereafter pass cart readers and unloaders 28 in FIG. 2, which identify the particular cart in terms of the large item in that cart and discharge the item at an appropriate hopper 12. The par ticular mechanisms to effect the foregoing functions are now discussed.

Turning first to the mostly schematic representation in FIG. 3, the cart llA thereshown is moved in a closed-loop path along

tracks

20A and 20B upon wheels 21A and ZIB by a closed-loop chain 22 leg, :1 chainveyor" sold by the Chainveyor Corporation of Florence, Kentucky). The chain is moved in the closedloop path by an electric drive motor 23, turning through reduction gearing, a chainwheel gear (not shown), interacting forces being transmitted to the cart 11A through a pin 24 which contacts a drive dog 25, as later discussed in connection with FIG. 7. Lateral position of the cart 11A is assured by guide wheels 26A and 268 that roll along a closed-loop guide 27. The particular situation depicted in FIG. 3 is that of a cart 1 IA positioned at the unloading area where, as detailed in later paragraphs, a hinged floor 68 of the cart is opened to effect discharge of a large item being carried by the cart to an appropriate unloading hopper. The chain and further related elements are not shown in FIG. 2 since that would merely complicate the already cluttered figure without adding anything of substance. It will be appreciated that the carts 11B are driven by a similar system. The monitoring and unloading scheme above discussed, of course, applies to either of the carts 1 1A or 1 B.

Returning again to FIG. 2, it will be observed that the carts 11A and 11B in the region of the

chutes

9 and 10 are queued. The purpose of such queuing and related matters are now discussed mostly with reference to FIGS. 2, SA, 58 and 5C.

As noted elsewhere herein, each of the large-item outputs of the vibrating

screens

2C and 2D is eventually conveyed by belt or gravity to an appropriate closed-loop track. The specially designed passive carts 11 are the essential element in this stage of the process. As an individual object tumbles off the end of the conveyor belt into one of the stationary carts (of which there may be several available if several closed-loop tracks are used for each screen output), a detector such as the photodetector labeled 18 in the chute 10, FIG. 2, senses its passage, and a special circuit triggers a mechanism for rapidly removing the cart. Proper design of the system creates a high probability of a cart being loaded with only a single object.

The ability of the carts II to perform their primary function of isolating single objects is dependent on the abilities of both the detector 18 to discriminate individual objects sliding from the chute 9 or the chute l0 and off the vibrating screen, and the cart accelerator hereinafter discussed to punctually remove a loaded cart. With regard to accurate detection, one is faced with the task of answering the paradoxical question what is a single object or item? For purposes of the present disclosure a single item is defined as any material or materials still held together by any means after passage over the vibrating screen 2, such that if it is lifted against gravity by any portion or member, however large or small, the entire piece will rise. The definition admittedly is not a very strict one; intuitively it implies that any materials that are united mechanically, electrostatically. by adhesion, or by embedding will be considered single objects and. if collectively heterogeneous in nature. will be identified as such by the sensors.

In order that a single item only be carried in a cart 11. it is necessary that a cart be in position to receive a sin gle item and that it be removed quickly subsequent to the deposit ofa single item therein. The queuing system noted above is discussed later with regard to FIGS. 8A 8C. Acceleration of the queued carts is now discussed with reference to FIGS. SA-SC. where the carts II are designated A, B, C and D to simplify this explanation. The carts A-D are secured together in FIG. 5A and move as a unit, that is, they are accelerated as a unit in the direction of the arrow labeled 103 in FIG. 5B, and the foremost cart A is detached from the four-cart unit in FIG. SB and moves around the path toward the sensors, etc. under the influence of the chain in the manner to be described.

The acceleration of the carts is by a Scotch-yoke mechanism that includes a rotatable arm 30 in FIGS. SA-SC.

Since the power required in the process is nearly proportional to the number of carts in the queue, and to the third power of the steady-state angular velocity of the accelerator, an attempt should be made to keep this number as small as possible. On the other hand, it can be expected that the frequency of objects being fed to the carts 11 will be more than the average value approximately 50% of the time. Surge loads of two or more times this average frequency are quite likely. The system must be designed to function as well as possible with these load fluctuations.

The accelerator comprises an electric motor 31 that drives a clutch brake 32. The narrow horizontal arm 30 is attached to the vertical output shaft of the clutchbrake and is allowed to rotate through 180 when the clutch is engaged.

Ball bearings

30A and 30B are mounted on vertical studs set at exactly one cart-length apart on the arm 30 so that as the first bearing just emerges from a channel provided on one vehicle the other just enters a channel provided on the trailing vehicle as shown in FIGS. SA-SC. The motion given to each cart is a part of a simple harmonic acceleration, assuming instantaneous acceleration to constant velocity rotation of the horizontal arm. The equations of motion are presented in said thesis.

The photodetector discussed in said thesis has been designed so as to trigger the accelerator a small pre-set time interval after the leading edge of a single item of refuse has broken the light path. The time delay is determined by the distance the object must fall from the chute to the cart below and, to a certain extent, on the average size of the objects encountered. Difficulties arise when two or more objects are clumped together so as to appear as one or when single objects with transverse holes" appear as more than one object. A solution to this problem might involve more sophisticated sensing techniques, using light rays or otherwise. Intuitively, the greatest probability for accurate detection would be achieved if the feed conveyor (see the conveyor shown at 40 in FIG. 9) is operated at the highest possible speed so that, while the average feed rate in objects per second is maintained, the average physical spacing between items would be increased and minimal overlapping would occur.

The accelerator is a further limiting factor in the process because of the interrelation between speed, power, and response time. The clutch-brake which was used approaches a maximum output rate since. as the speed of the input increases, so also does the time required for the output to reach its rated speed. Diminishing returns occur with increased motor speed and. in general, the faster and more powerful clutch-brakes are also more sluggish, i.e.. require a longer time to reach full rated speed. A scheme to ameliorate the problems is discussed later in connection with FIG. 9. Also, the system shown in US. Pat. No. 3.673.966 (Wilson) may be used here.

The mechanism employed in latching the vehicles is shown in FIGS. 8A-8C with respect to the carts A and B in FIGS. 5A5C. A latch 33 is placed on the same side of the cart as the accelerator arm 30 since it is critical that the vehicles be immediately adjacent here in order for the accelerator wheels to mesh smoothly into the channels from one cart to the next. During the normal course of travel around the track the latch is in position shown in FIG. 8A, which prevents the carts from becoming connected while still permitting them to contact one another. This situation might occur if two carts are accelerated consecutively and the second strikes the rear of the first before the chain drive has engaged either, or as the vehicles join the loading queue beyond the point at which they are required to be mechanically united.

As the carts are driven into the area where the primary queue of five to six carts is formed, a cam 35 on the side of the track through a roller 34 lifts the latch 33 of cart B to the position shown in FIG. 8B, which allows it to unite to a stud 37 on cart A in front upon sufficient impact force. The cam 35 has surfaces designated 35A, 35B, 35C. and 35D in this set of figures. In FIG. 8B the roller 34 rides up the surface 35A to 35B as shown. As the first cart A is loaded and pushed out of position the cam surfaces 35C and 350 lift the head of the latch on the succeeding vehicle to the position shown in FIG. 8C, freeing the lead cart A.

After acceleration the slower chain drive system pushes the loaded carts around the remainder of the circuit of FIG. 2. Further details of the interacting mechanisms between the chain and the cart are now given with reference to FIGS. 7A-7C where the pin 24 is represented by an arrow to show the direction of movement of the chain. Each cart has the specially mounted drive dog 25 on its side for driving and for automatic queuing. FIG. 7A illustrates the normal position of the mechanism during constant-speed travel of the cart under the influence of the chain drive. The pin 24 pushes the bottom of a link 25B of the drive dog 25 and the forces are transmitted to the cart. The driving force between

links

25A and 25B inhibits rotation of the link 25A in one direction and a fixed stud 25E prevents motion in the other. The force applied to the link 25B is transmitted to the cart by the pin shown at 25C.

After dumping, as discussed elsewhere herein, the empty carts are required to line up behind the loading station in preparation for re-use. This stationary queue is of indeterminate length and the carts must be inde' pendent of the motion of the drive chain. As a driven cart approaches the stationary queue a spring-loaded deflector on the rear of the last vehicle causes the link 25A to rotate through a small angle which is sufficient to free link 25B of its enclosure and allow it to rotate through the angle (I) in FIG. 7C. As long as the vehicles are adjacent to one another the force of a spring 25D in said springloaded deflector is sufficient to hold the mechanism in the position shown in FIG. 7C while the pin 24 from the drive chain 22 passes underneath. When the cart at the loading position has been re moved, one-by-one the carts in the queue will be advanced by the chain until all again are stationary. When a cart is accelerated from the head of the queue it will in general be travelling initially at a speed greater than that of the pins 24 in the drive chain. and the link 25B will rotate to the position shown in FIG. 78 to allow the cart to pass by one or more pins 24.

Further important aspects of the carts II are now taken up with reference to FIGS. 3, 6A and 6B where the cart is again labeled 11A. It will be appreciated that the front-elevation view of FIG. 6B shows the interior of the cart IIA which has inclined

side walls

36 and 68. The single item of refuse being carried by the cart 11A will be near the upper part 67 of a slot in the cart, being held there in the course of transit around the loop by a filler track 38 which extends around the loop except at the region occupied by the sensors l3, l4 and 15, as shown in FIG. 4. In this way the piece of refuse is kept from falling or extending out of the cart and yet is ac cessible to the sensors.

The sensors 13, etc., obtain data from the contents of the cart and transmit the data to the control computer 16, the data are compared with information previously stored in the computer and, on the basis of this comparison, a decision is made concerning classification of the material. Reference may be made to the Senturia et al. U.S. Pat. No. 3,474,555 for a discussion of algorithm development for a general-purpose computer for this classification.

The computer-coding device employed in the system discussed in the thesis is a series of four toggle switches mounted vertically at the top and rear of each cart. A code is imprinted on the device by a bank of solenoids which mechanically lift the proper sequence of switches to identify the type of material contained in the cart. (Codes for sixteen different categories can be presented on the four switches.) The code is conveyed on the cart to the proper dumping station where it is read by a bank of micro-switches which are sensitive only to that code. A signal is subsequently relayed to an electro-mechanical actuator which opens the vehicle floor at the appropriate time as later discussed. The later two functions are performed by the cart readers and unloaders 28.

The dumping operation is performed by opening the side which acts as a false bottom or door 68. Design of the contour of the carts was chosen because, as noted. this configuration will be likely to cause most objects to lie on or near the sensor slot 67 with their long axes along the length of the vehicle. The floor piece is hinged at a point away from the side wall labeled 69 so that its full-open position allows the greatest free area through which objects might fall.

The bi-stable mechanism for supporting and operating the door 68 was chosen after many more complicated arrangements had proved unsatisfactory. A modest force is required to move the toggle-action dooropening mechanism I9 through the small displacement necessary to get over top-dead center in FIG. 6B; gravity, aided by the small spring force, rapidly completes the opening action. In the system described the force to initiate opening of the door 68 is provided by a roller 19A secured by an arm 19B to a linkage 19. The cart readers and unloadcrs cause a relay to close at an appropriate position of the track and thereby actuate a solenoid 19C which moves an appropriate cam (e.g., the cam labeled 19D in FIGS. 6A and 6B) into position to establish contact with the roller l9A. (An air blast from above may be used to cause quicker evacuation of the container.) Closing the door afte. dumping is accomplished by the cart traveling over a second cam (not shown) mounted on the track. The cam pushes the link I9 back over top-dead center until the linkage I9 is again in its stable position.

The mechanism 4 for removing loose paper and plastie is shown in schematic form in FIG. [0. Loose paper and plastic lifted from the vibrating screen 2 are sucked toward a nylon open-mesh belt 53 by air currents caused by a fan 54. The belt 53 moves in the direction of the arrow labeled 55 by an electric-motor geared drive 56 to the region of air jets 57 where paper is selectively removed through a funnel 58. Thereafter plasties are removed. While the belt 53 is in the vicinity of the funnel 58 the plastics can be retained on the belt by the electrostatic system described in a report entitled Recovering Plastics from Urban Refuse by Electrodynamic Techniques," Bureau of Mines, Dec. 1972, TPR 63, and subsequently removed by other air jets 59 into another funnel 60. Other systems can include the infrared sensors indicated in FIG. 2 with air blasts from the jets 57, appropriately timed.

The magnetized-belt system 3, as best shown in FIG. 11, consists of a belt 50 driven in the direction of the arrow labeled 104 by an electric motor drive 51. Magnetic pieces that bounce upward from the vibrating screen 2 are held by the belt 50 which is magnetized by a magnet 52 in the region immediately above the vibrating screen 2. Such magnetic particles drop from the belt 50, as indicated by the arrow labeled 105, once the belt leaves the region of influence of the magnet 52.

Some means for automatically monitoring the various elements in FIG. 2 is needed, particularly at the input end of the system 101. One monitoring scheme is shown in FIG. 9 which, in addition to system elements discussed in connection with FIG. 2, includes the conveyor 40 to receive single items from the vibrating screen 2. The items on the screen 2 move in the illustrative embodiment at l foot per second, whereas the conveyor 40 moves at 5 feet per second. In this way, the single objects are separated from one another to assure that each cart 11A will contain only one item. The object sensor 18, as shown, detects entry of a large item into the leading cart A of the queue of carts and is connected to actuate the acceleration means, designated 29 in this figure, for the cart A, as before discussed. In FIG. 9, a sensor 41, which can be a multi-height, multiple-light-beam arrangement, notes the depth of refuse on the screen 2 and is connected, as shown, back to the output of the feed hopper l to modulate the feed rate. A sensor 42 notes the frequency of objects on the conveyor 40 and it also is connected to modulate the feed rate from the feed hopper. A sensor 43 notes the length of the queue of carts or the occurrence of a preestablished minimum length and is connected. as shown, to control the speed of the conveyor 40 accordingly. For example, the conveyor 40 may be slowed when the queue reader indicates a pre-established short queue length, or the whole system may be stopped.

Further modifications of the invention herein described will occur to persons skilled in the art and all such modifications are deemed to be within the spirit and scope of the invention as defined by the appended claims.

What is claimed is:

1. A refuse'separation system that comprises, in combination:

pre-sorter means that includes means for mechanically agitating the refuse to break up clumps and to divide fines in the refuse from the large items therein and means to remove loose paper and plastie;

a plurality of carts, each being the leading cart of a queue of carts on a closed-loop track, positioned to receive the individual large items from the presorter means;

acceleration means to propel each leading cart down the track and to accelerate the next cart in queue into position;

object-detector means to detect entry of a large item into each leading cart and connected to actuate the acceleration means for that cart;

propulsion means to move each accelerated cart around its closed-loop track;

uncoupling means to discontinue the propulsion means when the cart encounters another cart in a queue of carts;

sensor means to provide signature-type messages from each individual large item and to provide a signal indicative of a plurality of characteristics of the individual large item present in each cart;

means for analyzing the signal to provide an indication of the character of the individual large item sensed; and means for removing the individual by the characteristics of the item as indicated by said signal and interpreted by the means for analyzing.

2. A refuse-separation system as claimed in claim in which the pre-sorter includes magnetic means to remove magnetic materials from the refuse prior to the refuse leaving the region of the pre-sorter.

3. A refuse-separation system as claimed in claim I in which the means for analyzing the signal is a small speciaLpurpose computer.

4. A refuse-separating system as claimed in claim 1 in which the sensor means includes an impact sensor and an infrared sensor.

5. A refuse-separation system as claimed in claim I in which the means for mechanically agitating the refuse and dividing the fines in the refuse from the large items therein comprises a multi-layer. vibrating screen.

6. A refuse-separation system as claimed in claim 1 that further includes a vortex classifier to receive the fines and to separate the same into categories on the basis of the density of the various fines.

7. A refuse-separation system as claimed in claim 1 that includes a water-jet bag-slitter associated with the pre-sorter.

8. A refuse-separation system as claimed in claim 4 in which the sensor means further includes a metal detector.

9. A refuse-separation system as claimed in claim I in which the pre-sorter means includes a plurality of suction means adapted to remove the newspaper and plastic.

10. A refuse-separation system as claimed in claim 1 in which the carts contain small slits at the lower portion thereof to allow insertion of the sensor means therethrough to permit sensing.

Claims

1. A refuse-separation system that comprises, in combination: pre-sorter means that includes means for mechanically agitating the refuse to break up clumps and to divide fines in the refuse from the large items therein and means to remove loose paper and plastic; a plurality of carts, each being the leading cart of a queue of carts on a closed-loop track, positioned to receive the individual large items from the pre-sorter means; acceleration means to propel each leading cart down the track and to accelerate the next cart in queue into position; object-detector means to detect entry of a large item into each leading cart and connected to actuate the acceleration means for that cart; propulsion means to move each accelerated cart around its closed-loop track; uncoupling means to discontinue the propulsion means when the cart encounters another cart in a queue of carts; sensor means to provide signature-type messages from each individual large item and to provide a signal indicative of a plurality of characteristics of the individual large item present in each cart; means for analyzing the signal to provide an indication of the character of the individual large item sensed; and means for removing the individual large item from each cart at a location determined by the characteristics of the item as indicated by said signal and interpreted by the means for analyzing.

2. A refuse-separation system as claimed in claim 1 in which the pre-sorter includes magnetic means to remove magnetic materials from the refuse prior to the refuse leaving the region of the pre-sorter.

3. A refuse-separation system as claimed in claim 1 in which the means for analyzing the signal is a small special-purpose computer.

5. A refuse-separation system as claimed in claim 1 in which the means for mechanically agitating the refuse and dividing the fines in the refuse from the large items therein comprises a multi-layer, vibrating screen.

9. A refuse-separation system as claimeD in claim 1 in which the pre-sorter means includes a plurality of suction means adapted to remove the newspaper and plastic.