WO2003010371A2

WO2003010371A2 - Method and device for classifying valuable material comprising at least one fibrous fraction

Info

Publication number: WO2003010371A2
Application number: PCT/EP2002/008285
Authority: WO
Inventors: Frank Scholz
Original assignee: Recover System Recycling Gmbh
Priority date: 2001-07-25
Filing date: 2002-07-25
Publication date: 2003-02-06
Also published as: WO2003010371A3; DE10135398A1; AU2002325366A1

Abstract

The invention relates to a method and a device for classifying valuable materials consisting of a viscoplastic fraction, particularly PE and PP films, and a fibrous fraction, particularly cellulose fibres, which enable an almost complete separation into cellulose fibres and plastics. To this end, the valuable materials are whirled up in the direction of a sieve (103) and the fibrous fraction is sucked through the same (103).

Description

Title: Method and device for classifying valuable material with at least one fiber fraction

description

The invention relates to a method and a device for classifying recyclable material consisting of at least one viscoplastic fraction, in particular plastic film residues, and a fiber fraction, in particular cellulose fibers, according to claim 1 and the independent claim 10.

In the manufacture of hygiene articles, in particular

Disposable diapers, incontinence articles and sanitary napkins, various plastic films and cellulose fibers are used to achieve the desired product properties. For example, the required tensile strength and tightness to the outside is achieved by plastic films made of polyethylene and / or polypropylene (PE or PP). The comfort is adjusted by other, liquid-permeable foils. Cellulose fibers can be provided between these foils, which serve to absorb liquid.

There is always a certain amount of waste in the production of hygiene articles. This committee, hereinafter referred to as "recyclable material", is to be broken down into its constituents, hereinafter referred to as a fraction, to relieve the environment and for economic reasons, so that these can be reused without any loss of quality.

From EP 1 050 613 AI is a method and Device for classifying such valuable materials is known. The device used to carry out the method consists of a channel which rises in the conveying direction. The bottom of this channel is formed by a sieve. There is a negative pressure on the side of the screen facing away from the inside of the channel. Transversely to the longitudinal direction of the channel, several rollers with driver pins are arranged one behind the other in the conveying direction. The position of the rollers and the length of the driver pins is selected such that a gap remains between the driver pins and the screen when the rollers are set in rotation.

To classify the recyclable material consisting of plastic film residues and cellulose fibers, the recyclable material is introduced into the channel at the lower end thereof. The rotating rollers use their driver pins to grasp the valuable material cut into strips and pull it through the gap between the driver pins and the sieve. Due to the friction and shear between the plastic film residues and the cellulose fibers, the plastic film residues and the cellulose fibers are separated or separated from one another. The cellulose fibers separated from the plastic film residues are sucked through the sieve by the negative pressure which prevails on the side of the sieve facing away from the channel. This process is repeated for each of the several rollers arranged one behind the other. When the plastic film residues have reached the end of the channel, a significant part of the cellulose fibers originally adhering to them has been removed and removed through the sieve. The pulp fibers suffered almost no loss of quality, since the pulp fibers were not subjected to high mechanical loads during classification. However, there are still considerable amounts of cellulose fibers on the plastic film residues, which were not separated from the plastic film residues by this very gentle process. Out For this reason, the plastic film residues can no longer be used and there is a considerable loss of cellulose fibers.

Typically, this classifying device is loaded with a valuable material consisting of 90% cellulose and 10% PE and PP, whereby significantly less than half of the total cellulose present can be recovered. The majority of the existing pulp remains with the plastic fraction and cannot be recovered. Because of the remaining high proportion of cellulose in the plastic fraction which arises at the end of the classification process according to the prior art, this plastic can no longer be used. This plastic fraction consists of approximately 70% cellulose and 30% plastic film residues.

The invention has for its object to provide a method and an apparatus which improves the classification of valuable materials with at least one tough elastic fraction and a fiber fraction in such a way that the yield of reusable valuable materials is increased.

This object is achieved according to the invention by a method for classifying recyclable material consisting of at least one viscoplastic fraction, in particular plastic film residues, and a fiber fraction, in particular cellulose fibers, in which the recyclable material is whirled up in the direction of a sieve, and the fiber fraction () is sucked through the sieve and the tough elastic fraction is withdrawn in a direction substantially parallel to the sieve.

In this process, the plastic fraction and the pulp fraction are whirled against the sieve at different speeds and intensities because of their different properties, so that the pulp fraction is almost without Impurities can be drawn off through the sieve. Since the valuable material is only whirled up, the cellulose fibers are not or only insignificantly damaged, so that there is no loss of quality in the cellulose fibers.

The effectiveness of the method according to the invention can be further increased if the method is carried out several times in succession, and / or before the classification, the material is separated into a fiber fraction and a tough elastic fraction.

It has proven to be particularly advantageous to carry out the separation with several intermeshing rollers.

A further improvement of the method according to the invention is obtained if the valuable material is shredded into strips of more than 50 mm in length before being classified or separated, in particular in a twin-shaft shredder.

In a further embodiment of the method according to the invention, clogging of the screen with the fiber fraction, in particular by means of a scraper, is prevented.

It is provided according to the invention that the material is whirled up so gently that the fiber fraction is only insignificantly damaged thereby and in particular the mean fiber length of the fiber fraction remains almost unchanged.

The above-mentioned object is also achieved according to the invention with a device for classifying recyclable material consisting of at least one viscoplastic fraction, in particular plastic film residues, and a fiber fraction, in particular cellulose fibers, with a housing, the interior of the housing being changed from a sieve into one first room and a second room is subdivided, with a device arranged in the first room for whirling up the valuable substance, the pressure in the second room being lower than in the first room. With this device, the o g. Advantages of the invention can be realized.

In order to supply the valuable material and to remove the residual material, first openings and a third opening for removing the residual material are provided in the first space.

In a further addition to the invention, it can be provided that a second opening for drawing off the fiber fraction is present in the second space.

In one embodiment of the invention, the device for whirling up valuable material comprises a rotor with a rotor shaft and at least one row of rotor blades, so that whirling takes place in a simple and effective manner, the at least one row of rotor blades consisting of a plurality of rotor blades distributed over the circumference of the rotor shaft.

It has been found to be gentle on the pulp if the rotor blades whirl up the material mainly in the radial direction and if the rotor blades are rounded and have a smooth surface.

In a further addition to the invention, the sieve is arranged coaxially with a longitudinal axis of the rotor shaft and encloses the rotor. It can be advantageous if the rotor axis is arranged eccentrically to the screen. The classification is further improved by the different distances between the rotor and the sieve given in this arrangement.

In order to prevent clogging of the sieve, a cleaning device can be provided which places the sieve on cleans its side facing the first space, for example by means of a scraper, preferably in the direction of the third opening.

Further advantages and advantageous refinements of the invention are described in the following drawing, its description and the following patent claims.

Show it:

FIG. 1 shows an exemplary embodiment of a device according to the invention for classifying valuable materials,

Figure 2 is a flow diagram of a plant for the complete recycling of valuable materials with a tough elastic fraction and a fiber fraction and

FIG. 3 shows a material flow diagram of the plant according to FIG. 2.

In Fig. 1, a device according to the invention for classifying recyclable material consisting of at least one viscoplastic fraction and a fiber fraction is shown schematically in longitudinal and cross-section. A screen 103 is also arranged in a housing 101. The screen 103 extends over the entire length of the housing 101 and encloses a rotor 105. The rotor 105 consists of a rotor shaft 107 and a plurality of rows of rotor blades 109 arranged on the rotor shaft 107. The rotor shaft 107 can also be arranged eccentrically to the screen 103.

The screen 103 has a large number of holes (not shown) over its entire surface. The diameter of the rotor blade rows 109 are dimensioned such that there is a sufficiently large distance between the rotor blade rows 109 and the sieve 103 in order not to damage the to avoid the pulp fibers shown by breaking or the like as far as possible. The rotor shaft 107 is rotatably supported in the housing 101. A first opening 107 is provided in a first end wall 117 of the housing 101, through which the valuable material to be classified (not shown) can be introduced into the inside of the sieve 103.

The rotor shaft 107, which is driven by a drive (not shown), detects the valuable material to be classified with its first rotor blade row 109 and distributes it in the first space 120 delimited by sieve 103, first end wall 115 and second end wall 119. The valuable material is whirled up and drawn in in the radial direction on a longitudinal axis 121 of the rotor shaft 107 in the direction of the sieve 103.

In the case of the recyclable material, there is no longer any cohesion between the viscoplastic fraction and the fiber fraction even before being put into the housing 101. Therefore, the fiber fraction, which is much shorter than the viscoplastic fraction, can be drawn off through the sieve 103. This is supported by the fact that in a second space 125 delimited by sieve 103, first end wall 115, second end wall 119 and an outer wall 123 of housing 101, a negative pressure prevails with respect to first space 120.

The pulp fibers (not shown) located in the second space 125 are drawn off through a second opening 127. The plastic film residues, not shown, and parts of the fiber fraction are conveyed by the rotor blade rows 109 in the direction of the second end face 119 and finally drawn off through a third opening 129.

The cylindrical shape of the screen 103 can be clearly seen in the cross section along the line AA in FIG. 1. It can also be clearly seen that the distance 113 between Blade 131 of blade row 109 is so large that there is no damage to the fiber fraction in the gap formed between blades 131 and sieve 103. Furthermore, it can be seen particularly clearly in this illustration that the rotor blades 131 of one rotor blade row are arranged offset to the rotor blades 131 of the neighboring rotor blade row 109. On the screen 103, which has a cylindrical shape in the exemplary embodiment according to FIG. 1, webs or other obstacles, not shown, which brake the movement of the fractions can be provided.

The blades 131 of the blade rows 109 are designed in such a way that they do not cut the fiber fraction under any circumstances and, if possible, do not break it either. In addition, the holes in the sieve 103 are rounded, so that no damage occurs to the fiber fraction even when it passes through the sieve 103. In addition, the speed of the rotor shaft 107 is chosen so low that the forces acting on the fiber fraction do not cause damage to the fiber fraction by breaking or the like.

In order to increase the effectiveness of the classification, a plurality of devices according to the invention can be connected in series, the residue removed from the previous device consisting of a viscoplastic fraction and residues of a fiber fraction being introduced into the first opening 117 of the subsequent device. The rotational speed of the rotor shaft 107, the distance 113 between the rotor blade rows 109 and the sieve 103 and the design and number of the rotor blades of the rotor blade rows 109 can differ from one another in the case of a plurality of devices arranged one behind the other, since the proportion of the fiber fraction decreases from one device according to the invention to the next device according to the invention. In the last device according to the invention, for example, the speed can be compared to The previous one must be significantly increased in order to ensure that as far as possible no fiber fraction with the viscoplastic fraction is drawn off through the third opening 129. As a result, the fiber fraction drawn off in the last device is of very poor quality, but this is economically negligible because of its small amount.

In this case, it is particularly advantageous that the viscous-elastic fraction that has been drawn off is present almost without impurities and can therefore be recycled in a particularly simple manner.

In order to prevent the sieve 103 from clogging, a scraper 133 can be provided, which is mounted in the first space 120 concentrically with the rotor shaft 107. The scraper 133 rotates slowly relative to the sieve 103 and removes fiber residues from the openings of the sieve 103 (not shown). The scraper 133 can also exert a conveying movement in the direction of the third opening 129 on the fiber fraction or the plastic fraction.

FIG. 2 shows a flow diagram of a system for recycling valuable materials consisting of a tough elastic fraction and a fiber fraction, in which several devices according to the invention according to the exemplary embodiment of FIG. 1 or other embodiments are integrated. Because of the detailed legend, this flowchart is only briefly described.

The valuable materials to be separated can consist, for example, of a composite of PE and PP mixed with cellulose flakes. The cellulose flakes can make up 50% by weight or more. Of course, the method according to the invention is not restricted to these areas, but it can be used with great success in the named area. In a first method step 1, the valuable substance is comminuted, for example, by a twin-shaft reducer. The comminuted recyclable material, the strip length of which can be greater than 50 mm, is then conveyed via a trough chain conveyor 2 into a bunker 3. From the bunker 3 the recyclable material 6 is conveyed. This can advantageously be done by intermeshing rollers. The valuable substance then arrives at a first device 8 for classification according to the invention.

Classification creates two material flows. The first material flow consists of cellulose flakes of first quality, which are then passed through a filter 37. The second material flow, which arises during classification in the device 8 according to the invention, consists of plastic film residues and unclassified cellulose fibers and is the so-called residual material. The residual material is fed by a pneumatic conveyor 9 into a second classifying device 10. This in turn creates two material flows, one consisting of first-class pulp and is conveyed to the filter 37 by a pneumatic conveyor 33.

The residual material drawn off from the first space 120 of the sieve 103 (see FIG. 1) is placed in a cyclone 13 and separated there. Secondary pulp flakes are obtained.

In a third device 16 according to the invention for classifying, the second material flow 14 which emerges from the cyclone 13 is classified again. Third-quality cellulose flakes can be obtained. This classifier 16 exerts relatively high forces on the fibers. In addition, the pressure difference between the first space 120 and the second space 125 is relatively large. This leads to partial damage to the fibers and the proportion of plastic in the separated fiber fraction is also comparatively high.

The second residue from the device 16 is conveyed via a pneumatic conveyor 17 to a second cyclone 19. The aim of this separation is above all to get the viscoplastic fraction free of cellulose fibers, since this complicates the recycling of the viscoplastic fraction, which typically consists of PE and / or PP.

In FIG. 3 the material flows are shown quantified as they pass through the plant described with reference to FIG. 2. From this illustration it is clear that the system works very effectively and the device according to the invention classifies the recycled materials in a fiber fraction of very high quality and a plastic fraction very effectively.

Starting from a total of 1,000 kg, consisting of 700 kg of pulp and 300 kg of polyethylene and polypropylene, after separating (see No. 6 in FIG. 2), 250 kg of a fiber fraction is obtained in a first classification process, which consists of 98% cellulose fibers and contains 2% impurities consisting of PE and PP.

The remaining 750 kg of residual material now consists of 61% cellulose and 39% PE and PP. After a second classification (see 10 in FIG. 2), a further 200 kg of cellulose are obtained, the cellulose being contaminated with 2% PE and PP. This total of 450 kg of pulp has been referred to in FIG. 2 as first quality pulp.

The remaining 550 kg of residual material now consists of 47% cellulose and 53% PE and PP. Contaminated cellulose fibers and plastic film residues are deposited in a cyclone (see 13 in FIG. 2). This will be 50 kg Pulp contaminated with 5% PE and PP is obtained. This pulp was referred to in Fig. 2 as 2nd quality pulp flakes.

The remaining amount of recyclable material of 500 kg, consisting of 42% pulp and 58% PE and PP, is then reclassified, which leads to a yield of 175 kg pulp contaminated with 10% PE and PP. This amount of pulp was referred to in Fig. 2 as 3rd grade pulp. The classification takes place in a device according to the invention (see 16 in FIG. 2).

The remaining amount of valuable material of 325 kg is then separated again in a cyclone (see 19 in FIG. 2), which leads to a further 25 kg of cellulose, the cellulose being contaminated with 5% plastics. This pulp was referred to in Fig. 2 as 3rd grade pulp. What remains is a plastic fraction, this plastic fraction consisting of 270 kg PE and FP, while the remaining 30 kg consist of cellulose fibers. This plastic fraction can be reused, for example in injection molding or other processes.

It is clear from the material balance according to FIG. 3 that the devices (8, 10 and 16) according to the invention produce very high quality cellulose flakes which can be fed back into a production process without further treatment. The third-quality pulp flakes make up only 175 kg, corresponding to 25% of the total amount of pulp. There are also uses for these third-quality cellulose flakes, so that these cellulose flakes can also be re-coupled into a manufacturing process. The plastic fraction obtained also has a high degree of purity of 90%, so that it can be reused. The method according to the invention, like the devices according to the invention, thus makes a significant contribution to the reuse of valuable substances without loss of quality. For comparison, it should also be mentioned that the classifying device according to the prior art is able to recover significantly less than half of the total cellulose present from a valuable material consisting of 90% cellulose and 10% PE and PP. The majority of the existing pulp remains with the plastic fraction and cannot be recovered. Because of the remaining high proportion of cellulose in the plastic fraction, which arises at the end of the classification process according to the prior art, this plastic can no longer be used.

The device according to the invention is able to further separate and classify this contaminated plastic fraction with the above-mentioned. Results. From this comparison it becomes clear what increases in the yield, the recovery of cellulose fibers and almost pure plastic by the device according to the invention, the method according to the invention and the plant according to FIG. 2 are possible.

Claims

claims

1. Method for classifying valuable material consisting of at least one viscoplastic fraction, in particular plastic film residues, and a fiber fraction, in particular cellulose fibers, characterized by the following method steps:

- whirling up the valuable material in the direction of a sieve (103),

- Sucking off the fiber fraction through the sieve (103) and

Conveying the viscoplastic fraction in a direction essentially parallel to the sieve (103).

2. The method according to claim 1, characterized in that the method is carried out several times in succession.

3. The method according to claim 1 or 2, characterized in that prior to classifying (8, 10, 16) a separation (6) of the valuable material into a fiber fraction and a tough elastic fraction.

4. The method according to claim 3, characterized in that the separation (6) of the valuable material is carried out by at least two intermeshing rollers.

5. The method according to any one of the preceding claims, characterized in that the valuable material is shredded before classifying (8, 10, 16) or separating (6).

6. The method according to claim 7, characterized in that the valuable substance in a two-shaft shredder (1) is crushed.

7. The method according to claim 5 or 6, characterized in that the valuable substance is shredded into strips of more than 50 mm in length.

8. The method according to any one of the preceding claims, characterized in that the clogging of the sieve

(103) with the fiber fraction, in particular by a scraper (133), is prevented.

9. The method according to any one of the preceding claims, characterized in that the material is whirled up so gently that the fiber fraction is only insignificantly damaged as a result and in particular the mean fiber length of the fiber fraction remains virtually unchanged.

10. Device for classifying recyclable material consisting of at least one viscoplastic fraction, in particular plastic film residues, and a fiber fraction, in particular cellulose fibers, with a housing (101), the interior of the housing (101) being passed from a sieve (103) into a first space ( 120) and a second room (125) is divided, with a device arranged in the first room (120) for whirling up the valuable substance, the pressure in the second room (125) being lower than in the first room (120).

11. The device according to claim 10, characterized in that in the first space (120) a first opening (117 for introducing recyclable material and a third opening (129) are provided for withdrawing the residual material.

12. The apparatus of claim 10 or 11, characterized characterized in that a second opening (127) is provided in the second space (125) for drawing off the fiber fraction.

13. Device according to one of claims 10 to 12, characterized in that the device for whirling up valuable material comprises a rotor (105) with a rotor shaft (107) and at least one rotor blade row (109).

14. The apparatus according to claim 13, characterized in that the at least one row of blades (109) consists of several blades (131) distributed over the circumference of the rotor shaft (107).

15. The apparatus according to claim 14, characterized in that the rotor blades (131) whirl up the material predominantly in the radial direction.

16. The apparatus according to claim 14 or 15, characterized in that the blades (131) are rounded and smooth.

17. The device according to one of claims 10 to 16, characterized in that the screen (103) is arranged coaxially to a longitudinal axis (121) of the rotor shaft (107), and that the screen (103) surrounds the rotor (105).

18. The apparatus according to claim 17, characterized in that the rotor shaft (107) is arranged eccentrically to the screen (103).

19. Device according to one of claims 10 to 18, characterized in that a cleaning device for the sieve (103) is provided that the

Cleaning device cleans the sieve (103) on its side facing the first space (120).

20. The apparatus according to claim 19, characterized in that the cleaning device has a scraper (133).

21. Device according to one of claims 10 to 20, characterized in that the device for classifying is preceded by a device (6) for separating the fractions contained in the valuable substance.

22. Device according to one of claims 10 to 21, characterized in that the device for classifying (8, 10, 16) is preceded by a device for comminuting the valuable material.

23. Device according to one of claims 10 to 22, characterized in that the device for whirling up valuable material comprises a roller-shaped rotor with a plurality of blades running parallel to a longitudinal axis of the rotor.