Machine and method for separating recyclable matter

A machine for sorting recyclable matter includes a trommel for conducting and screening an input flow of recyclable matter and a magnetic mechanism coupled to the trommel for extracting magnetic material from the input flow while the trommel rotates. The input flow is dropped vertically from the trommel into a positive-pressure air separator which separates the flow into a first material stream including lightweight articles and a second material stream including relatively heavy articles. The heavy articles of the second material stream drop downwardly in the air separator. Padded baffles are provided in the air separator for reducing the downward velocity of the second material stream, which substantially lowers breakage of glass articles.

BACKGROUND OF THE INVENTION 
This invention concerns a machine for separating a heterogenous flow of 
recyclable matter into respective separate streams of recyclable material, 
with each stream including a respective homogenous class or classes of 
articles. 
Machines are known which receive a heterogenous flow of recyclable matter 
and separate the flow into respective streams which include one or more 
homogenous classes of material. Presently, most of these machines separate 
the input flow into at least three separate material streams. The first 
stream includes magneto-responsive articles such as tin cans and ferrous 
scrap. The second stream consists of relatively light materials such as 
aluminum cans, plastic containers, and paper objects. The third stream 
includes relatively heavy articles such as glass containers, which are not 
responsive to a magnetizing force. 
The known machines employ magnetic means to extract magneto-responsive 
materials. The resulting stream of recyclable matter is separated into the 
second and third streams by applying a high-velocity air flow, either in 
the form of a vacuum or a high-pressure air stream, to blow the lighter 
articles away from the heavier articles. The three streams are directed by 
these prior art machines to respective conveyor mechanisms for transport 
to sorting stations where human operators further classify and sort the 
streams. 
Separator machines which are known in the art exhibit several significant 
disadvantages. First, most provide a stream of input matter which has been 
densified by collection, transport, and storage. The input stream is 
typically input to a separator machine on a conveyor, without having been 
loosened. This makes it more difficult to process the stream for 
separation and tends to retain small waste particles in the constituent 
materials, even after separation. 
The relatively dense input flow leads to a second significant disadvantage 
of known separator machines. Such machines typically extract 
magneto-responsive articles relatively early in the separation process. 
Indeed, two such machines remove magneto-responsive articles at the top 
end of an inclined conveyor which carries the input stream. Early removal 
from a relatively dense stream frequently results in other articles being 
pulled out of the input stream with the magneto-responsive articles. 
Moreover, a dense and deep input stream can block or dislodge 
magneto-responsive articles from a magnetic extractor. Further, the 
mechanisms for extracting the magneto-responsive articles are large, 
expensive, and difficult to maintain. 
A third significant disadvantage of known separator machines is the high 
breakage rate of glass containers. The glass containers normally are 
divided from other containers in an air separator which allows the glass 
containers to drop vertically. In such machines, glass containers are 
allowed to free-fall through the air separator mechanism to a conveyor. 
The conveyors move the glass containers at a relatively low speed, which 
results in falling glass containers impacting on other containers which 
are being transported by the conveyor. The result is a high frequency of 
glass-glass collisions and a very high rate of glass breakage. This is 
undesirable because of the potential of harm to human operators, because 
of the difficulty of extracting the broken material, and because of the 
creation of a significant amount of non-recoverable waste in the form of 
small glass particles. 
SUMMARY OF THE INVENTION 
The invention is based on the inventor's critical observation that 
positioning a trommel to receive the input flow of recyclable matter 
advantageously agitates the input flow, thereby reducing its density, and 
the further observation that an endless magnetic belt positioned at the 
output of the trommel effectively separates magneto-responsive articles 
from the agitated input flow. The inventor's third critical observation 
was that provision of baffles significantly reduced the velocity, the 
article-to-article impact and, therefore, the breakage of 
vertically-falling glass articles in an air separator. 
These critical observations have resulted in the invention of a machine for 
separating recyclable matter. The machine includes: 
a frame; 
a trommel mounted to rotate on the frame, the trommel having an input 
opening and an output opening for conducting a flow of recyclable matter; 
an endless magnetic belt coupled to the trommel for extracting magnetic 
material from the flow of recyclable matter in response to rotation of the 
trommel; 
a positive-pressure air separator mounted on the frame adjacent the trommel 
for: 
receiving the flow of recyclable matter; and 
separating the flow of recyclable matter into a first material stream 
including relatively lightweight articles and a second material stream 
including relatively heavier articles; 
the air separator providing the second material stream in a substantially 
downward direction; 
padded baffles in the separator for reducing the downward velocity of 
articles in the second material stream; 
a first collection area; 
a first conveyor mounted on the frame adjacent the air separator to receive 
the first material stream for conveying the relatively lightweight 
articles to the first collection area; 
a second collection area; and 
a second conveyor mounted on the frame adjacent the baffles to receive the 
second material stream for conveying the relatively heavy articles to the 
second collection area. 
With this invention, magneto-responsive articles are easily removed from 
the flow of recyclable matter to a significantly reduced accompaniment of 
other articles. The invention also effectively separates relatively 
lightweight articles from heavier glass articles with an unexpected and 
surprising reduction in glass breakage. 
These benefits, and other features and advantages of the invention will be 
appreciated when the following detailed description is read with reference 
to the below-described drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention is a machine for separating recyclable matter, a 
preferred form of which is shown in FIGS. 1-3. The machine is referred to 
generally by reference numeral 10, and it includes a frame 12 on which a 
trommel 14 is rotatably mounted. The trommel 14 includes an open input end 
16 into which an input flow of recyclable matter is provided by 
conventional means which are not shown, but which can include, for 
example, a hopper and an upwardly-extending conveyor. The trommel 14 is 
rotatably mounted by conventional means on the frame 12 and rotates 
thereon to agitate and loosen the input flow of recyclable matter. At the 
same time, non-recyclable waste in the form of relatively small particles 
is separated from, and screened out of, the agitated input flow through 
the perforations 18 in the side surface of the trommel. This waste is 
collected and conducted from the trommel through a chute 17 positioned on 
the frame 12, underneath the trommel. The trommel is mounted at a slant so 
that its open discharge end 19 is relatively lower than its input end 16. 
The discharge end 19 of the trommel is the lower periphery of an 
unapertured annulus 21 between the apertures 18 and the discharge end 19. 
Magneto-responsive materials are extracted from the agitated, screened 
input flow in this annulus 21 and are received in a chute 23 having a 
receiving end 25 that projects through the discharge end 19 into the 
annulus 21. The mechanism for extracting the magnetic materials from the 
agitated, screened input flow is illustrated in FIGS. 6, 7, and 8. 
The mechanism for extracting magneto-responsive articles (also referred to 
as "magnetic" articles) includes a magnetic endless belt mechanism 30 that 
includes a pair of parallel endless belts 31. The belts are, preferably, 
assembled from metallic links that are durable enough to support and carry 
a plurality of elongate bar magnetics 35 which are coupled to the endless 
belts 31. The magnetic endless belt mechanism passes around the annulus 21 
and a belt roller 37 which is spaced from the trommel 14. As best seen in 
FIGS. 7 and 8, the belt roller 37 includes two teethed portions which 
engage the links and the endless belts 31. The magnetic endless belt 
mechanism 30 is tensioned between the belt roller 37 and the annulus 21 so 
that the belt mechanism is in driving engagement with the trommel 14. The 
magnetic endless belt mechanism may either idle on the trommel 14 as the 
trommel is rotated by means which are well-understood but not illustrated, 
or it may be used to drive the trommel, assuming a suitable means (not 
shown) for driving the belt roller 37. 
In operation, the trommel 14, magnetic endless belt mechanism 30, and drive 
roller 37 all rotate together. Assuming rotation in the direction 
indicated by the arrow 39 in FIG. 8, magnetic articles in the agitated, 
screened input flow of recyclable matter are attracted by the magnets 35 
whose fields extend through the inner surface of the annulus 21. The 
magnetic articles are held against the inner surface of the annulus 21 
until they reach the location indicated by the article 40. At this 
location, the magnetic endless belt mechanism 30 disengages from the 
annulus 21, which quickly reduces and soon eliminates the magnetic field 
which holds the magnetic article 40 against the inner surface of the 
annulus. When this occurs, the magnetic article 40 drops along the path 
indicated by the dotted arrow 42 and is received in the end 25 of the 
chute 23. The chute 23 conducts the magnetic article 40 to an exit point 
24 where the article drops out of the chute into a collection bin (not 
shown). The inventor contemplates that other mechanisms could serve the 
function of the chute 23 in receiving and conducting away magnetic 
articles from the trommel 14. For example, out feed from the trommel could 
be by way of a conveyor parallel to the trommel and mounted to extend part 
way into the annulus 21. 
Returning to FIGS. 1, 2, and 3, the materials in the input flow of 
recyclable matter which do not respond to the magnetic endless belt 
mechanism fall out of the discharge end 19 of the trommel 14 onto a 
conveyor 41. These materials are provided by the conveyor 41 to an air 
separator 44. 
The air separator 44 includes a continuous closed duct with a lower section 
46 (which is shown partially cut away in FIG. 1 for purposes of 
illustration). As best seen in FIGS. 2 and 3, the lower duct section 46 
transitions to a closed upper section 47. The air separator 44 includes a 
high-capacity blower 45 which communicates with the duct 46, 47, blowing a 
high velocity stream of air at a positive pressure into the lower duct. 
The stream of air is deflected upwardly in the duct 46 by a baffle 49. The 
high-velocity air stream continues upwardly in the chute section 46 along 
the path indicated by the solid arrows 50. The high-velocity air stream is 
conducted through the upper chute section 47 to a cyclone mechanism 52 
with an upper exit port 54 and a lower exit port 56. 
In operation, the air separator receives the agitated, screened input flow 
of recyclable matter from which magnetic materials have been removed. The 
flow falls off the end of the conveyor 41 into the lower duct section 46. 
As the flow of matter falls vertically toward the baffle 49, it is further 
agitated by the high velocity air stream so that relatively light articles 
such as plastic and aluminum containers, other plastic articles, and paper 
articles are transported by the stream of air in a first material stream 
upwardly in the lower duct 46 through the upper duct 47 into the cyclone 
52. The cyclone 52 operates conventionally, circulating the stream of air 
and condensing it at its lower end so that an upwardly moving, low 
pressure area is formed in the center of the cyclone which conducts very 
light material such as plastic bags, sheets of paper, and so on, from the 
first material stream to the upper output port 54 while heavier articles, 
such as plastic and aluminum containers are thrown to the wall of the 
cyclone 52 and fall downwardly along the wall through the output port 56. 
Preferably, a duct 55 connected to the upper output port 54 conducts the 
very light materials from the cyclone 52 to a collection area (not shown). 
Returning to FIG. 1, the high velocity stream of air is not sufficiently 
powerful to propel heavier articles, such as glass containers, upwardly in 
the lower chute 46. Consequently, these articles fall downwardly off the 
end of the conveyor 41, forming a second stream of relatively heavier 
articles. The downward velocity and the impact force of articles in the 
second material stream are reduced by the baffle 49 and a second baffle 
58. As shown in the cross-section of FIG. 1, the baffles 49 and 58 are 
curved in such a manner that articles in the second material stream follow 
the path indicated by the dashed arrows 59, falling first to the first 
baffle 49 where their downward fall is intercepted and translated 
horizontally and wherefrom the articles fall to the second baffle 58, 
which again translates the falling direction of the articles into a 
substantially horizontal direction. Preferably, the baffles 49 and 58 are 
padded with a hardy resilient material which will absorb much of the force 
of impact produced when articles fall against the baffles. The padded 
baffles 49 and 58 significantly reduce the breakage of articles in the 
second material stream. 
As FIGS. 2 and 3 illustrate, the first and second material streams are 
directed to spaced-apart, substantially parallel conveyors 65 and 67 which 
are conventionally mounted and conventionally driven on the frame 12. The 
air separator upper duct 47 extends transversely above these conveyors 
between the lower duct section 46 and the cyclone 52. The conveyor 65 
receives the relatively heavier articles in the first material stream 
which fall out of the exit end 56 of the cyclone 52 and conduct those 
articles past a sorting location 66 where a human operator may stand and 
visually classify and manually sort articles in the first material stream. 
Similarly, the second conveyor receives articles in the second material 
stream, conveying them past a sorting location 68. 
As FIGS. 1 and 2 illustrate, the lower baffle 58 in the air separator 44 
horizontally translates the direction of articles falling downwardly in 
the lower duct section 46 into a direction parallel with the direction of 
movement of the conveyors 65 and 67. This places the articles on the 
conveyors and contributes significantly to reduction of breakage. 
A respective conveyor is positioned beneath each of the conveyors 65 and 
67. These conveyors, 70 and 71, are provided to receive trash and other 
non-recyclable objects which may be carried with the first and second 
material streams. Such objects would be manually removed by the human 
operators positioned at the sorting locations. 
FIGS. 4 and 5 illustrate a second embodiment of the invention in which the 
separator machine described above and indicated generally by reference 
numeral 80 in these two figures is mounted on a raised mezzanine 90. In 
this embodiment, the mezzanine 90 elevates the sorting machine 80 above 
floor level 92. The input flow of recyclable matter fed to the trommel 80a 
is provided from an input hopper 95 from which it is raised to the input 
end of the trommel 80a by an upwardly-inclined conveyor 97. As shown in 
FIGS. 4 and 5, the first and second material stream conveyors 80b and 80c 
pass sorting locations which are served by sorting chutes, such as the 
chutes 98 and 99. 
The embodiment of FIGS. 1, 2, and 3 is intended to be a relatively portable 
one, easily stored, transported, and assembled, and then easily 
disassembled for relocation. The second embodiment illustrated in FIGS. 4 
and 5 is intended to be a relatively permanent installation adapted for 
high-speed, high-volume separation assisted by a plurality of human 
operators. 
Obviously, many variations of the above-described embodiments will occur to 
one skilled in the art and such variations may be made without departing 
from the spirit and scope of the claims which follow.