DE3800204A1 - Method and apparatus for sorting plastic refuse - Google Patents

Abstract

A method for sorting plastic refuse makes use of the different relative densities of the different types of plastic. The sorting takes place in that the comminuted refuse is introduced into a liquid medium having a predetermined relative density, the heavier parts then sinking and the lighter parts floating so that they can be removed separately. This sorting method can be repeated by the use of a plurality of liquid media of graded relative densities. An apparatus for sorting plastic refuse of different relative densities comprises one or more containers which in each case are filled with a liquid of predetermined relative density and contains a removing apparatus for the particles which have sunk to the bottom and a further removing apparatus for the floating particles. The particles removed at the top then pass via a drying drum to the filling station. Containers of this type can be connected one behind the other in any desired number and having liquids of increasing relative density.

Description

The invention relates to a method and a Device for sorting plastic waste, the are in the form of small particles. If bigger Plastic items should be available, they should Crushed beforehand to make sorting easier will.

Sorting plastic waste was previously practically not possible because there are many plastics types despite very different chemical Structure according to its appearance hardly or not at all made a distinction, especially if they were colored.

Because there is a conglomerate of different plastics types, for example PVC, polyethylene, polyacrylate, Polyamide, do not process together, for example wise to a homogeneous melt Previously, sorting of plastic waste waived at all and the environment created by it burden inevitably accepted. Given the avalanche-like growth of the garbage piles becomes one Solution to this problem, ie an elimination of the im Garbage-containing plastic parts, increasingly urgent.  

The previously practiced practice, plastic-containing Burning garbage is also no solution represents, but has a particularly heavy impact on the environment due to the occurrence of caustic or toxic burns products.

The invention is accordingly based on the object a method and an apparatus for sorting To create plastic waste, which is then a Further processing of sorted plastics, for example by melting into compact plat or the like.

This task is regarding the procedure solved according to the invention in that the particles different types of plastics according to their specific Weight can be sorted by putting it in a liquid Medium are introduced, their specific weight between the specific weights of the present Plastic types is, and then that each floating and the sunken plastic part be brought out of the medium on their own. So in the simplest case, two types of plastic are present, the specific weight of which is sometimes below and partly above the specific weight of Water lies, you could sort water as use liquid medium.

As liquid media of higher specific gravity would then be aqueous salt solutions and as such lower specific gravity certain organic Suitable for liquids.

When choosing these liquids you will of course, have to make sure that they dissolve none of the plastics to be sorted out or attack in any other way. Stand for it  for example from the range of aromatic coals Hydrogen an external number of substances for Available.

Since plastic waste is usually more than two types of plastic will be preferred suggested sorting in two or more Stages using two or more liquid specific media to take. The one in one is preferably used in each case Medium sunken part of the plastic particles in one subsequent medium somewhat higher specific Weight introduced and again in two Fractions of different specific weights disassembled.

Further features of the method according to the invention result from the patent claims.

To solve the problem regarding a device it is also proposed to use one or more each predetermined with a liquid medium specific Use weight-filled containers that are open at the top and on the one hand on the floor and on the other hand on the Liquid surface of the medium one transport each to provide facility that on the one hand the abge sunken or on the other hand the floating Takes up plastic particles and, separately from the other, from the container.

Further features of the device according to the invention result from the subclaims directed to it chen. Basically, in all versions device according to the invention important, the specifi cal constant within each container to keep. On the one hand, this requires a good one Temperature control in every container, because the speci cal weight of the available liquid  Substances is temperature dependent.

On the other hand, the composition is the same of the liquid medium. So at Use of aqueous salt solutions and at Series containers with several stages have ascending specific gravity in each the first container after the container hauling thinner liquid out at the brought attached plastic particles that are specific Weight gradually reduced. It will therefore proposed to compensate for this harmful Dosing concentrate into the containers, until the desired specific weight is restored. That happens after one another proposal of the invention in a very simple Way, that the leading to the container Abge concentrate line with a float valve is closed, the one immersed in the medium Swimmer is made of the same material as the plastic to be deployed upwards. So you can the float by melting one each certain amount of that out of this container produce brought plastic particles.

The invention is described below with reference to the drawing explained in more detail in exemplary embodiments. Here demonstrate:

Fig. 1 shows a schematically simplified depicting lung of a container according to the invention, seen along line II in Fig. 2,

Fig. 2 shows a section along the line II-II in Fig. 1;

Fig. 3 is a view in the direction of arrow III in Fig. 1;

Fig. 4 is a schematically simplified sectional view along the line IV-IV in Figure 5 by an assembly of six containers.

Fig. 5 is a view in the direction of arrow V in Fig. 4 and

Fig. 6 is a schematic representation of an overall system with nine sorting containers.

The container 1 shown in FIGS. 1 to 3 is cuboid in its upper part and approximately funnel-shaped in its lower part and filled with a liquid 6 as a medium.

As can be seen from Fig. 1, the side walls of the container converge in a funnel shape at the lower part and meet a bottom channel 5 , in which a rotatable screw 8 is located.

The container 1 is loaded from above in the direction of arrow VII with small-sized plastic waste, whereupon those plastic particles whose specific weight is greater than that of the liquid medium 6 , sink and get into the floor channel.

As can be seen from FIGS. 2 and 3, the bottom gutter extends from the right end of the container almost to the center thereof. From there on, the trough rises at a certain angle and finally merges into a riser pipe 9 leading obliquely upwards, in which there is also a screw 29 . Correspondingly, the below the riser pipe 9 finally converging side walls of the container obliquely upwards, so that even such plastic particles that occur at the left end (in Fig. 2 and 3) of the container, the bottom channel 5 are fed, if their specific Weight that exceeds the medium.

The container is carried by four supports 2 and 3 in connection with two cross supports 4 . In the spaces between these supports and the lower limit of the container, further device parts, for example an electric motor for the drive, can be accommodated.

The shaft of the screw 8 extends through the vertical wall of the container 1 at the right end ( FIGS. 2 and 3) and is driven from there. In the illustrated embodiment, the worm shaft carries a pulley 27 through which the connection to an electric motor can be made.

Between the two screws 8 and 29 there is a cardan coupling 28 which drives the screw 29 , simultaneously with the screw 8 . The direction of the slope and the speed of the two screws are selected such that plastic particles falling into the bottom channel 5 are conveyed to the left and then diagonally upwards within the riser pipe 9 until they finally leave the downwardly curved outlet 30 of this pipe in the direction of the arrow 31 .

At the upper edge of the container, on one of its two longitudinal edges, there is an impeller 10 which is rotated in the direction of arrow 11 by a drive (not shown). The path of the wings or paddles of this impeller 10 leads closely past a curved screen plate 12 , the lower edge of which lies approximately below the shaft of the impeller 10 , while the upper edge is connected to the edge of the container. The arrangement is such that the floating, lighter plastic particles are grasped by the vanes of the impeller 10 and transported along the sieve plate to the upper edge of the container, with entrained liquid largely running off at the openings of the sieve plate 12 (only shown schematically).

The plastic particles then fall over the edge of the container into a groove 13 arranged along the side, which extends over the entire length of the container. In this channel 13 there is a worm 14 which carries a pulley 26 at its right end ( FIGS. 2 and 3) as a worm drive. The worm conveys the plastic material thrown into the trough by the impeller 10 to the right and finally lets it get into the downpipe 15 . This downpipe leads to the right end ( Fig. 3) of a rotatable drying drum 16 with helical baffles in its interior. The drying drum 16 , which is mounted on support rollers 17 and driven from there, and which is heated (not particularly shown), conveys the plastic material fed from the downpipe 15 in the direction of arrow 32 to the left into the drain pipe 18 , which finally leads into a slightly oblique downward direction ver running transport pipe 19 opens out. Air is fed to this transport tube at 20 , which feeds the plastic particles falling from above to the outlet 21 .

It should also be noted that the worm 8 and with it the worm 29 , the worm 14 , the impeller 10 and the drying drum 16 are driven by a common motor (not shown).

The funnel-shaped beveled design of the container ( Fig. 1) not only offers the advantage that the material falling from above is fed to the bottom channel 5 . In addition, it is possible because of this bevel, to put containers of this type close to one another, in which case the impeller projecting above the upper container edge 10 finds space in the free space below the beveled bottom of the container above it.

As can be seen from Fig. 1, the container can be supplied through an inlet pipe 24 concentrate for the liquid medium, provided that it is, for example, an aqueous salt solution. The concentrate is supplied at 25 and enters the container 1 when the float valve 23 is open. The float 22 shown in simplified form consists of a plastic which is to float in this container and is to be applied upwards. The float thus has approximately the specific weight of the liquid in this container. As soon as liquid particles of lower specific weight adhering to a previous container are introduced into this container when several such containers are connected, the specific weight of the liquid gradually decreases, so that the desired sorting effect would then no longer be achieved. Before this happens, however, the float 22 sinks and releases the inflow for the concentrate. The specific weight of the medium is thus kept constant in a simple manner.

Structural details, such as a parallel guidance of the float 22 , are not shown here. You will also need to keep the liquid level in the container constant in a similar manner by another float valve or by an overflow, but this is not the subject of this invention.

Also heating and regulating a desired one Liquid temperatures are not in the figures shown because their execution for the specialist by itself.

In Figs. 4 and 5 is shown the manner in which a multiple sorting by means of six containers 1 a to 1 f can be carried out. These containers are arranged in two columns of three on top of each other and filled with liquids of increasing specific weight. The plastic particles to be sorted are fed through a transport blower 34 and a riser 35 and an outlet 36 to the first container 1 a . The floating particles, as can be seen from FIG. 5 , are discharged via a down pipe 15 a and a drying drum 16 a and can be packaged. The sunken plastic particles are transported through the riser 9 a in the next container 1 b and there, with a liquid of a slightly higher specific weight, sorted again. The floating particles are again fed via the impeller and the downpipe to a drying drum and from there to the filling. The sunken particles ge long over a riser pipe 9 b in the underlying container 1 c , which, like the following container 1 d, is formed in mirror image of the upper two containers. From the container 1 c , the sunken particles then enter the container 1 d . The particles that have sunk there pass through the riser pipe 9 d into the container 1 e underneath and the particles sunk there via the riser pipe 9 e into the last container 1 f . The particles sinking there are then fed to a waste container 37 via the riser pipe 9 f . It will no longer be plastic particles when the specific weights of the individual containers are appropriately chosen, but rather stones, metal parts or the like. The sorting system according to FIGS. 4 and 5 has sorted the mixture supplied by the transport blower 34 into six fractions of different specific weights and a proportion of waste.

In Fig. 6, an entire system is schematically Darge, which further illustrates the possible uses of the invention. The plastic waste supplied by a loader 80 is thrown into a collecting pit 81 and from there through a transport device 82 , for example a conveyor belt or a screw, introduced into a shredder 83 . After the wastes have been crushed there, they arrive in a washing facility 86 via a further conveyor 84 . The washing water is taken up by a collecting container 85 and can be worked up further by known methods.

The pre-shredded and washed material then passes through a further conveyor 87 into a mill 88 , in which the pieces of plastic film and the like are now ground into even smaller plastic parts. From there, the plastic particles get into a conveyor blower 89 and from there into a hopper 90 , which feeds this mixture of different plastics to the first sorting container 41 . Floating material is, as schematically indicated, fed through a pipe 51 to a hopper 61 and from this to a filling container 71 .

The sunken material arrives in the next sorting container 42 . The material floating there is fed via the pipeline 52 to the filling funnel 62 and from there to the filling container 72 . In this way, the remaining material passes through the containers 43 , 44 , 45 , 46 , 47 , 48 and 49 in order . The floating material is transported through the pipes 53 to 59 in the hopper 63 to 69 and from there into the Abfüllbe container 73 to 79 in each container.

The material that has sunk in the last container 49 , that is to say stones, metal parts and the like, is ejected into a waste container 40 .

Reference symbol list:

1 container
2 supports
3 supports
4 cross supports
5 floor channel
6 liquid
7 arrow
8 snail
9 riser pipe
10 impeller
11 direction of rotation
12 sieve plate
13 gutter
14 snail
15 downpipe
16 drying drum
17 carrying rollers
18 drain pipe
19 transport pipe
20 air supply
21 exit
22 swimmers
23 valve
24 inlet pipe
25 concentrate entry
26 pulley
27 pulley
28 cardan coupling
29 snail
30 outlet
31, 32 arrows
34 transport blower
35 riser
36 outlet
37 rubbish bins
40 rubbish bins
41-49 sorting container
51-59 piping
61-69 hopper
71-79 filling container
80 tippers
81 collecting pit
82, 84, 87 sponsors
83 shredder
85 collection containers
86 car wash
88 mill
89 conveying blowers
90 hopper

Claims (20)

1. A method and apparatus for sorting plastic waste in the form of small particles, characterized in that the particles of different types of plastic are sorted according to their specific weight by being introduced into a liquid medium, the specific weight of which is between the specific weights of the present types of plastic , and that the floating and the sunken plastic particles are then brought out of the medium for themselves. 2. The method according to claim 1, characterized ge indicates that sorting in two or more stages using two or more liquid media graded specific weight, the respective part of the plastic sunken in a medium particles in a subsequent medium higher specific weight and again divided into two fractions specific weight is disassembled. 3. The method according to claim 1 or 2, characterized characterized that the specific Weight of a medium by regulating the Concentration and the temperature constant will.   4. The method according to claim 1 to 3, characterized characterized that the after Fractions of different specific Ge weight assorted and applied plastic particles dried and each for transport bags or containers are filled. 5. Apparatus for carrying out the method according to claim 1 to 4, characterized by one or more, each with a liquid medium predetermined specific Ge weight-filled, open-topped container ( 1 ), arranged in the or each container, from the sunken plastic particles receiving and dispensing end of the container first transport means (5, 8, 29, 9) and arranged in the upper part of the or each container, the set schwommenen plastic receiving and out of the container, separate from the first-mentioned plastic, discharge end second transport means (10 , 12 , 13 , 14 ). 6. The device according to claim 5, characterized in that the first transport device a arranged at the bottom of the container channel ( 5 ) with a chen in it rotatable first screw ( 8 ) and an adjoining the approximately in the middle of the container end of the channel, diagonally upward and out of the container pipe ( 9 ) with a rotatable therein second screw ( 29 ), wherein the side walls of the container run approximately funnel-shaped obliquely downwards towards the trough ( 5 ) and wherein the conveying device of the first screw ( 8 ) towards the lower end of the tube ( 9 ) and that of the second screw upwards towards the upper end of the tube ( 9 ). 7. Apparatus according to claim 5 and 6, characterized in that the second transport device is a rotatable impeller ( 10 ), the shaft of which is arranged somewhat above the liquid level of the medium near a container wall, and the wing of which is in circulation in each case Immerse the medium, take the floating plastic part there and bring it out of the container via a curved sieve plate ( 12 ) that extends from below the impeller to the top of the container. 8. The device according to claim 7, characterized by a along the upper edge of the container, outside the container, the upper edge of the curved sieve plate ( 12 ) adjacent channel ( 13 ), a rotatable third screw ( 14 ) arranged in the channel and a down pipe ( 15 ) adjoining the end of the trough ( 13 ) and the screw ( 14 ) for the removal of the plastic parts. 9. Apparatus according to claim 6 to 8, characterized in that the shaft of the first screw ( 8 ) through the container wall leads GE and is connected to a drive. 10. The device according to claim 9, characterized in that the second screw ( 29 ) is connected by a cardan coupling ( 28 ) to the first screw ( 8 ). 11. The device according to claim 8 to 10, characterized in that the third screw ( 14 ) is driven by the same drive as the first and the second screw. 12. The apparatus of claim 8 to 11, marked by a along the loading container, below the channel ( 13 ) with screw ( 14 ), arranged rotatable, heated drying drum ( 16 ), in one end of which the downpipe ( 15 ) opens and at the other end a drain pipe ( 18 ) for the dried plastic particles is connected, wherein within the drying drum ( 16 ) helical ver baffles are arranged so that they promote the plastic particles introduced from the downpipe ( 15 ) to the drain pipe ( 18 ) . 13. The apparatus according to claim 12, characterized in that the drying drum ( 16 ) is driven by the same drive as the three screws ( 8 , 29 , 14 ). 14. The apparatus according to claim 5 to 13, characterized characterized in that the medium in Container heated and by a temperature controller constant at a predetermined temperature is held. 15. The apparatus according to claim 5 to 14, characterized characterized that the concentra tion of the medium through a regulated inlet is kept constant. 16. The apparatus according to claim 15, characterized by a float valve ( 22 , 23 ) for regulating the supply of concentrate, the float closing the valve when rising consists of the same plastic, which should float in the container and be discharged above. 17. The apparatus according to claim 5 to 16, characterized draws through the series switching of two or more containers with gradually increasing specific weight of the liquid medium. 18. The apparatus according to claim 17, characterized characterized that the container are arranged one above the other. 19. The apparatus according to claim 17, characterized characterized that the container are arranged side by side. 20. The apparatus of claim 17 for at least four Container, characterized thereby net that the containers in columns on top of each other and arranged in groups next to each other.