DE19629470C2 - Process and plant for processing mixed plastics - Google Patents

Description

The invention relates to a method for processing Mixed plastics according to the preamble of claim 1 and a plant for this according to the preamble of claim 10.

When processing mixed plastics, regular ßig particles that have a certain, predetermined weight or exceed a certain, predeterminable density animals. These sorted out particles are called heavy fractions tion. It can be, for example, the Acting heavy air discharge from a windsifter.  

The heavy load associated with the processing of mixed plastics fraction is very heterogeneous. In addition to hard Plastics of different sizes and other dickwan Digen plastics it contains inert substances, such as. B. glass, Metal and damp paper made from beverage bags or Frozen packaging comes. In addition, the Heavy fraction also foil parts because of the mixed art stock preparation the separation of light and heavy goods can never be done with 100 percent accuracy.

This heterogeneously composed heavy fraction is at the mixed plastics processing was previously disposed of as waste, because processing from an economic point of view does not seem to make sense. So are from DE 43 24 237 A1 a method and an apparatus for processing Shaped bodies made of different polymers known which is density-like or even density-equal polymers be separated in order to process them separately can. For this purpose they will consist of polymers several times by impact and / or impact and then sieved according to their size separates. Suction devices are also provided, by means of whose heavy goods are removed from the material to be processed which is then disposed of as waste. Here but this heavy cargo regularly has large amounts of plastics contains, this means that when processing Mixed plastics currently have large amounts of plastic waste to be produced.

CH 530 822 describes a method for separation below different types of plastic waste known by type of plastic, at which u. a. Particles that exceed a certain density ten, separated as a heavy fraction and then in one Grinding station can be transformed into granules. This However, the method is not suitable for the preparation of Mixed plastics, the inert materials, such as. B. glass, metal and paper included.

The invention is based, which in the Processing of mixed plastics sorted out by Schwerfrak tion so that a later thermal or raw material recycling is made possible.

This object is achieved by a method with the features of claim 1 and with a system solved the features of claim 10.

Some embodiments of the method according to the invention and the system according to the invention are not only for treatment development of the mixed plastics processing  Heavy fraction suitable, but can also be from it independent when processing hard plastics Zen.

The invention is based on the knowledge that the Processing of mixed plastics sorted out by Schwerfrak tion with a relatively simple and inexpensive Gen process can be prepared so that a raw material recovery of the contained in this heavy fraction Plastics is easily possible. It is necessary for this Lich, the heavy fraction in a separate treatment crushing device by impact and / or impact and then seven.

The separate preparation of the heavy fraction means that in the processing of mixed plastics Plastic waste significantly reduced. Because while so far the plastics contained in the heavy fraction as Waste has been disposed of, it is now in a separate treatment device treated so that too these plastics are recycled can be.

It should also be borne in mind that the heavy fraction from mixed plastic processing not only hard plastic fe in the narrower sense, e.g. B. polystyrene, but also thick-walled parts of softer materials, such as B. Polypropy len and polyethylene. This is u. a. due to  that when sorting out the. Heavy fraction during mixed plastic processing, which is often a windsich tion is used, both density and weight of plastics play a role. (Basically, the Separation of a plastic mixture into a light fraction and a heavy fraction by weight or by density respectively. It is also a combination of these sorting steps te conceivable, so that for example only substances that a exceed a certain weight and density, be attributed to the heavy fraction. It is also important to note that in practice (wind classification) sorting often do not separate according to density and weight.)

In the method according to the invention, it has proven special proved advantageous that the heavy fraction by Impact and / or blow is crushed. For example a hammer mill can be used.

By crushing the heavy fraction by impact and / or impact, the following effects which are very important for the treatment result are achieved:

• 1. The hard plastics reliably adhere freed the inert substances, so that the latter as fines can be screened. This will also make the Ashean part in the material to be processed significantly reduced. This is of great importance for a later raw material recovery.  
• 2. When shredded, damp or soaked paper is frayed by impact or impact. This facilitates the later separation of the paper from the plastics. Without prior crushing by impact or impact, the weight of the wet paper parts is very similar to the weight of the plastics, so that a reliable separation of these components is hardly possible.
  Such effects can be achieved by crushing the heavy fraction by cutting or shearing, e.g. B. in a shredder. With these shredding processes, the damp, soaked paper parts tend to form lumps, which can make it even more difficult to separate them from the plastics later.
• 3. When crushing by impact and / or impact, especially in a hammer mill, you get despite a high proportion of inert substances, e.g. B. glass, a even grain. This allows for a later one Time of electrostatic sorting of the plastics fe.

To relieve the crushing stage and only those Lead particles to the size reduction stage at which crushing is actually necessary it should be provided that a coarse or medium grain sieve is switched, with the larger grains be screened from the heavy fraction, and that only this sieved grains passed into the crushing stage become. The smaller components of the to be processed  Materials (i.e. the screen underflow) can be at the Zer reduction stage over to the next preparation stage be directed.

The coarse or medium grain sieve is, for example, such designed that the screen overflow is formed by grains, which have a size of more than about 10 mm. Self ver Of course, any other criterion can also be used Select rium for separating the grains by size.

About the proportion of fine-grained inert substances and the PVC proportion to reduce in the heavy fraction and by a uniform to obtain the grain size during processing according to the invention those grains that have a certain fall below a predefinable size (e.g. 1 mm to 2 mm) with sieved a fine grain sieve and from the processing pro removed.

It has been shown that the combination of a fine grain sieving with a previous crushing by impact and / or impact to surprising results regarding the quality of the processed plastics. At The laboratory was able to test under laboratory conditions PVC portion of the (which is a hindrance to further utilization) processed material below 2%. Also the other inert substances, such as. B. glass, are in the aufbe rode plastic goods only in such small quantities the fact that it will later be used for raw materials, e.g. B. as a reducing agent for the steel industry, not oppose.  

As a supplement to the screening of fines, in the case of small particles removed from the material to be processed is at the inventive method also a pneumatic Ent removal of light goods, such as B. foil parts, paper and The like. Provided.

It has proven to be particularly advantageous if the light goods by means of a suction device, the above arranged the flow of the material to be processed is suctioned off. Alternatively, it is also possible the light goods by means of a wind sifting from the others Separate components of the heavy fraction.

Since in the plants for the processing of mixed plastics Separation of magnetic components from the process the material is never 100% (or only after sorting out the heavy fraction), it is advantageous, albeit in the separate facility for Processing of the heavy fraction removed magnetic substances become. This step should preferably be the same stand at the beginning of the preparation of the heavy fraction. there can both deposit ferromagnetic materials by means of a magnet as well as the separation of non-egg senmetallen (paramagnetic materials) by means of a Non-ferrous metal separator, e.g. B. by an eddy current divorce.

When processing mixed plastics, the heavy components mostly with the help of an air classifier sorted out. Therefore, to carry out the present Procedure to provide transport and / or funding, with which the heavy air discharge of the air classifier to the separate  Facility for the preparation of the heavy fraction can be changed. In particular, it can be provided that the system for the processing of mixed plastics and the separate facility for processing the heavy fraction NEN are arranged in the immediate vicinity, so that the transport of the heavy fraction via a stationary one Conveying device, for example a metering trough, is successful can.

Which of the above-described procedural steps in the Preparation of the heavy fraction in the individual if actually applied, depends on a. depending on which treatment the heavy fraction already during the Mixed plastic processing was subjected. Often done the sorting out of the processing of mixed plastics Heavy fraction only after the material has already been crushed, magnetic and / or non-magnetic Components exempted, sieved or otherwise has been treated. The more extensive and thorough the Treatment before sorting out the heavy fraction was the less effort is required for the subsequent preparation of the Heavy fraction required.

Some of the previously described embodiments of the invention However, the method according to the invention is not only suitable for Preparation of the heavy fraction in a plant for Mixed plastic processing was sorted out, but it are generally used for the processing of hard plastics (e.g. polypropylene, polycarbonate, engineering plastics) suitable.  

Regardless of the context in which the method according to the invention is used, a particularly advantageous embodiment is characterized in that

• a) magnetic substances from the material to be processed be removed
• b) particles that have a certain, predeterminable size step out of the material to be processed sieves, crushed to the predefinable size and returned to the material to be processed the,  
• c) the fine grain fraction, in particular particles with a Size from less than 1 mm to 2 mm from which to open riding material is screened,
• d) Light goods from the material to be processed by means of at least one arranged above the material flow Suction device is suctioned and
• e) the material to be processed in a homogeneous silo is settled.

The process makes a plastic product of such high quality created that this for sorting without problems can be sorted electrostatically.

The inventive method for the preparation of mixing plastics, in which the heavy fraction in a separate treatment facility is preferred wisely carried out with a system by the characteristics of claim 10 is characterized.

This facility enables with simple, inexpensive Means performing the method according to the invention.

Preferred embodiments of this system are in the Subclaims 11 to 19 claimed.  

In a particularly preferred embodiment, the processing plant according to the invention has the following processing stages:

• a) a magnetic separator,
• b) a coarse grain sieve, the sieve overflow discharge with a Hammer mill is connected, with the sieve below run discharge of the coarse grain sieve and discharge of the Hammer mill connected to further processing stages are,
• c) a fine grain sieve,
• d) a suction device for light goods and
• e) a mixing silo.

Further advantages of the invention will be apparent from the following Description of an embodiment with reference to the drawing become clear.

It shows:

Figure 1 is a diagrammatic representation of a device for processing the heavy fraction that was sorted out in the mixed plastic processing.

Fig. 2 is a schematic representation of a Absaugvor direction for light goods.

In the embodiment shown in FIG. 1, the various parts of the heavy fraction, which were sorted out in a system for processing mixed plastics, are brought together in a store 1 . Such a combination of different parts of the heavy fraction can, for. B. may be necessary because in the Mischkunststoffaufbe processing system several wind classifiers are operated in parallel, each of which is heavy. The heavy goods of these air classifiers are brought together at position 1 , where they can be stored temporarily.

The brought together in the camp 1 heavy fraction can be directed via a metering channel 5 in a separate device 11-45 for processing the heavy fraction.

This separate spreading device comprises, as the first processing stage, an overband magnet 11 , the magnetic discharge of which is connected to a recyclable material container 12 and the non-magnetic discharge of which is connected to a coarse-grain sieve section 21 .

The coarse-grain sieve section 21 is designed, for example, in such a way that grains with a size of more than 10 mm form the sieve overflow and smaller grains form the sieve underflow. The screen overflow discharge of the screen section 21 is passed to a hammer mill 22 , while the screen underflow discharge is connected to a fine-grain screen 31 .

The discharge of the hammer mill 22 is fed back to the coarse-grain screen section 21 . Alternatively (or additionally) it is possible for the hammer mill 22 to have a sieve insert which is only permeable to grains having a size of less than 10 mm. In this case, the discharge of the hammer mill 22 can be connected directly to the fine-grain sieve section 31 , see the dashed line 1 .

The fine grain sieve section 31 is designed such that grains with a size of less than 1.6 mm as a sieve underflow at position 32 are supplied for thermal recycling. The screen overflow discharge is in contrast passed under a pneumatic suction device 35 formed by a suction bell, with the light components, such as. B. film parts, paper and the like. From which can be sucked off on the material to be prepared.

After passing through the suction device 35 , the material to be processed arrives in a mixing silo 41 . There it can be homogenized before it is prepared for further transport in the bagging station 45 .

The method according to the invention is carried out as follows with the device for treating the heavy fraction from the mixed plastic preparation shown in FIG. 1:
The heavy material discharge from various wind sifters arranged in parallel in a mixed plastics processing system is collected at position 1 as a heavy fraction. This heavy fraction usually went through several process steps in the mixed plastic processing plant before it was sorted out by wind separation. For example, pre-comminution, separation of magnetic materials, sorting out of inert substances, predrying and sieving can already be carried out. Nevertheless, the heavy fraction always contains other components, such as hard plastics of different sizes. B. glass, metal and damp paper. In particular, pre-drying in mixed plastic processing plants is not sufficient to bag soaked drinks or to dry freezer packaging completely.

This heavy fraction of a mixed plastic preparation system is supplied via a metering trough 5 to the separate preparation device 11-45 .

The heavy fraction first passes through an overband magnet 11 , as a result of which magnetic materials are deposited and collected in a recycling container 12 .

The material to be processed is then passed over a coarse-grain screen section 21 . Particles with a size of less than 10 mm form the sieve underflow. These are sucked off pneumatically and guided to a fine-grain sieve 31 on a vibrating trough.

The screen overflow discharge from the screen section 21 is comminuted in a hammer mill 22 and then guided back onto the screen section 21 . Overall, it is ensured that only particles with a size of less than 10 mm are passed to the fine-grain sieve section 31 .

Of particular importance in these first process steps is the crushing of the heavy fraction in the hammer mill 22 . Adhesive inert substances are removed from the plastics in the hammer mill. The latter can then be sieved using a fine-grain sieve. Furthermore, damp and soaked paper is crushed and unraveled in the hammer mill 22 . This enables pneumatic separation of the paper in further process steps. Finally, it is noteworthy that a hammer mill produces a very uniform plastic grain even with a high proportion of foreign substances. This is important in order to be able to electrostatically separate the processed material by type of plastic later.

The material which has been optimally prepared for further processing with the aid of the hammer mill 22 and the coarse-grain sieve 21 and is comminuted to a size of less than 10 mm is now sieved on the fine material sieve section 31 . Particles with a size of less than 1.6 mm are removed from the material to be processed and collected in a container 32 , from where they can be fed, for example, to thermal recycling.

It has been shown that by screening the Feinkornan partly on the sieve section 31 inert substances, such as. B. glass, ash and PVC are almost completely removed from the heavy fraction to be processed. This is, among other things, a consequence of the previous crushing of the heavy fraction in the hammer mill 22 . Overall, it is achieved that the Schwerfrak tion contains inert substances only in such small amounts that they do not stand in the way of extensive thermal or raw material recycling of the processed material.

The screen overflow discharge of the fine-grain screen section 31 is passed under a suction device 35 (cf. FIG. 2) for further processing. In doing so, film components, paper and remaining ash residues are extracted from the heavy fraction.

The previous comminution of the heavy fraction in the hammer mill 22 is also of great importance for this process step; because in the hammer mill the paper and the film components were smashed and unraveled. As a result, these components were brought into a state that enables removal with the aid of an extraction bell.

The material sucked off by the suction device 35 is fed to a container 32 , where it is kept ready for further thermal utilization.

After passing through the suction device 35 , the heavy fraction consisting only of hard or thick-walled plastics is passed into the mixing silo 41 . The processed goods are homogenized there and kept ready for further use.

From the. Mixing silo 41 , the processed material is removed if necessary and conveyed to the bagging station 45 in preparation for removal.

With the above-described embodiment of the invention with simple means and a few procedural steps produce such a high quality plastic material that this for example by the steel industry as a reducing agent can be used. Unless it is for further recovery the plastics is necessary, these can also be elec trostatically separated and thus kept ready by type become. The sorting of the plastics by means of the homogeneity of the processed goods with a uniform Chen size of about 2 mm to 10 mm and by the extremely ge wrestle share of foreign substances.

The procedure described above can also be used for preparation use hard plastics that are not heavy fraction sorted out in mixed plastic processing were, but are incurred in a different context. It is only necessary to process it en It was comminuted well enough so that there were none contains band-shaped materials that are around the rotor of the Wind hammer mill and affect its efficiency.

A preferred embodiment of the suction device 35 , with which light material can be sucked out of the heavy fraction to be processed, is shown in FIG. 2.

The suction device 35 comprises a suction bell (diffuser 50 ) which is height-adjustable in the direction A and which is connected to a suction line 52 via a connecting part 51 . The suction line 52 is connected to a suction blower 54 and provided with an air flow regulator 53 with which the suction power can be varied.

The material to be processed is passed on a vibrating trough 58 under the suction bell 50 . A targeted te variation of the suction power determines which components are extracted from the mixture to be processed. The greater the suction power, the more (and the heavier) components are extracted as a light fraction.

By adjusting the distance between the suction bell 50 and the vibrating trough 58 , this can be adjusted from the size of the parts located on the vibrating trough 58 , which in turn depends on the size to which the material to be processed has previously been crushed.

The extracted light material is removed and closed at item 55 directed to a suitable storage location.

Claims (19)

1. A process for the preparation of mixed plastics containing inert materials such as glass, metal and paper, in which particles which exceed a certain density (heavy fraction) are sorted out, characterized in that the heavy fraction in a separate preparation device ( 11-45 ) is crushed by impact and / or impact, sieved to remove fine-grained inert substances, and the light goods, such as foils and paper, are removed pneumatically from the heavy fraction. 2. The method according to claim 1, characterized in that the heavy fraction is crushed in a hammer mill ( 22 ). 3. The method according to claim 1 or 2, characterized net that particles that have a certain, predeterminable size exceed, sieved from the heavy fraction, on crushed the predeterminable size and the heavy fraction be fed again. 4. The method according to any one of the preceding claims, characterized in that the light material is sucked off by means of a suction device ( 35 ). 5. The method according to any one of claims 1 to 3, characterized ge indicates that the light goods by a wind sifting is separated from the heavy fraction. 6. The method according to any one of the preceding claims, since characterized in that magnetic substances from the Heavy fraction to be removed. 7. The method according to any one of the preceding claims, characterized in that the heavy fraction is removed by means of an air classifier in a system for the processing of mixed plastics and that the heavy fraction via a stationary conveyor ( 5 ) of the separate processing device ( 11-45 ) is fed. 8. The method according to any one of the preceding claims, characterized in that

• a) magnetic substances are removed from the material to be processed with a magnet ( 11 ),
• b) particles that exceed a certain, predeterminable size, sieved from the material to be processed, crushed to the predefinable size and fed back to the material to be prepared,
• c) the fine grain fraction, in particular particles with a size of less than 1 mm to 2 mm, is sieved from the material to be processed,
• d) light material is extracted from the material to be processed by means of at least one suction bell ( 50 ) arranged above the material flow, and
• e) the material to be processed is homogenized in a silo.

9. The method according to any one of the preceding claims, characterized in that the processed material is sorted electrostatically. 10. Plant for the processing of mixed plastics, which contain inert materials such as glass, metal and paper, with at least one processing stage in which particles that exceed a certain density (heavy fraction) are sorted out.
marked by
a separate treatment unit ( 11-45 ) for the heavy fraction, which comprises:

• a) a comminution stage ( 22 ) which is designed to comminute the heavy fraction by impact and / or impact,
• b) a fine-grain sieve ( 31 ) for removing fine-grained inert substances and
• c) a suction device ( 35 ) for light goods, such as. B. film parts and paper.

11. Plant according to claim 10, characterized in that the size reduction stage ( 22 ) is ausgebil det as a hammer mill. 12. Plant according to claim 10 or 11, characterized in that the size reduction stage ( 22 ) has a sieve insert. 13. Plant according to one of claims 10 to 12, marked net by a coarse or medium grain sieve ( 21 ), the sieve overflow discharge is connected to the size reduction stage ( 22 ). 14. Plant according to claim 13, characterized in that the fine grain sieve ( 31 ) the coarse or medium grain sieve ( 21 ) and the size reduction stage ( 22 ) is switched. 15. Plant according to one of claims 10 to 14, characterized in that the suction device ( 35 ) has at least one, arranged above the material flow suction curl ( 50 ). 16. Plant according to one of claims 10 to 15, characterized in that the suction device ( 35 ) of the Zer reduction stage ( 22 ) and the fine-grain sieve ( 31 ) is switched on. 17. Plant according to one of claims 10 to 16, characterized by a magnetic separator ( 11 ) for removing magnetic substances. 18. Plant according to one of claims 10 to 17, marked net by a stationary conveyor ( 5 ) for transporting the heavy fraction from the system for the preparation of mixed plastics ( 1 ) to the separate device ( 11-45 ) for processing the heavy fraction. 19. Plant according to one of claims 10 to 18, characterized by the following via means of transport with each other at the associated processing stages:

• a) a magnetic separator ( 11 ),
• b) a coarse grain sieve ( 21 ), the sieve overflow discharge of which is connected to a hammer mill ( 22 ), the sieve underflow discharge of the coarse grain sieve ( 21 ) and the discharge of the hammer mill ( 22 ) being connected to further processing stages ( 31 , 35 ) ,
• c) a fine-grain sieve ( 31 ),
• d) a suction device ( 35 ) for light goods and
• e) a mixing silo ( 41 ).