NO168810B - PROCEDURE AND DEVICE FOR THE CREATION OF MIXED WASTE, AS HOUSEHOLD WASTE OR FRACTIONS THEREOF, FOR THE RECYCLING OF PLASTIC FILM MATERIALS - Google Patents

Description

The present invention relates to a method and a device for sorting out mixed waste, such as rubbish or fractions thereof, for separate recycling of on the one hand paper and on the other hand plastic foil materials, especially in recycling facilities.

This particularly concerns wet separation of paper and plastic films from mixed paper/plastic waste, e.g. from a waste recycling facility.

In household waste, depending on the geographical location, there is 30-40$ of paper and 6-12$ of plastic waste. Both materials can be reused without problems in industry if they are of satisfactory purity.

In waste recycling facilities, dry separation methods, e.g. air sieving or drum sieving known to sort out paper and plastic as separate fractions. The fractions can then be processed in special preparation processes into fiber material or plastic granules. A disadvantage is the high investment and operating costs and partly a poor separation sharpness for such dry separation methods. Degrees of pollution for the fractions of up to 30$ or higher are known.

If the paper is recovered in a recycling plant, then a pulp separation system and a clarification plant are also mostly present in the wet sorting process. In this process part, components foreign to paper are separated, i.a. also plastic foils, as unwanted material and thrown away. Consequently, the task consisted of also making this part reusable.

To solve this problem, according to the invention, by expanding the wet-dissolving system, it is proposed to separate and pre-clean both the valuable substances paper and plastic foils, so that these can be supplied directly to the further straightening process.

The present invention provides a method for the sorting of mixed waste, such as rubbish or fractions thereof, for the recycling of plastics, especially in recycling facilities, whereby a pre-sorted fraction containing plastic foils is processed in a pulping machine (pulpers), the obtained, especially paper-containing suspension is removed by using sieves, and the contamination phase, which constitutes the sieve residue, containing plastic foil is deposited. The method is characterized by the fact that for the recovery of the plastic part, a screening residue is collected from the contamination phase, the screening residue is taken out of the mass dissolver, crushed after removal of liquid and then the plastic foil part is separated from a liquid phase.

According to a still unpublished proposal from the applicant, liquid is advantageously removed from the screening residue that has been taken out by the pulp solver in a hole drum, whereby this screening drum can in particular partially dive into a bath of suspension liquid. Advantageously, the hole drum is designed as a stepped drum with a volume that decreases in the direction of transport and a central outlet and in particular has an inner spiral and/or pump pockets, so that the screening residue is not only carried forward in the hole drum, but also continuously dissolved and mixed, so that small proportions, such as stones, glass or metal parts, hard plastic parts and still unseparated paper fibers can exit the punching drum through the holes. The hole drum can also be formed as a cone drum with a narrowing in the transport direction; furthermore, the axis in the hole drum can run upwards in the direction of transport.

Removal of liquid from the sieve residue can take place in several steps; consequently, e.g. the material brought out of the hole drum is then extruded and densified in a press, especially a screw conveyor.

The material from which the water has been removed is then subjected to a division, which has at least one stage. Above all, it has proven appropriate to first finely chop the material in an essentially dry state to the size of the palm of your hand, e.g. in a regular finer, then slurried in a beaker with process water while moving, whereby adhering particles of contamination are released and heavy substances sink to the bottom of the beaker, and that the material on the surface of the liquid is removed and subjected to a preferably wet finer division to approx. fingernail size.

The light parts of this material, i.e. substances that float easily, such as wood or polystyrene foam, are then advantageously separated from the fraction to be recovered, i.e. plastic film residues, whose density is only slightly less than 1, i.e. that they float in water with just a little buoyancy. This takes place in a gravity flotation cup, in which a falling flow is maintained, the speed of this flow is greater than the buoyancy speed of the plastic film residues, so that these are carried by the flow, and preferably via a bottom outlet, exit the container together with process water, while the light parts floats up and can be removed.

A corresponding feature of the method according to the invention is that the dewatered and finely divided screening residue, especially after separation of heavy substances, as well as preferably after a further fine division, in a gravity flotation beaker is freed from flowable, light parts, such as wood or foam plastic, especially polystyrene foam, with the exception of plastic film residues.

For further purification, the opposite method is then chosen, namely a flotation of plastic film residues in process water. This serves above all for a final separation of substances that sink and float, and in particular for the separation of remnants of woven materials, especially woven remnants of plastic fabric, as it has been shown that these are an addition for the subsequent spreading of the plastic film remnants, whereby usually granules are obtained, constitute an extremely unfortunate and quality-reducing pollution.

These woven residues do not flow like the plastic film residues, but are easily included in the flowing process water.

According to the invention, it is therefore further arranged so that the dewatered and finely divided sifting residue is processed in a flow-flow Iotas ion beaker, in which the plastic foil residues rise to the surface of the liquid under the influence of the flow, are especially flushed upwards, and are removed from the surface.

This flow-flotation cup is advantageously, at least in terms of flow, divided into a flotation zone with a sedimentation funnel for extracting rapidly sinking contaminants and a resting or outflow zone, whereby an at least substantially horizontally directed liquid flow is maintained in the buoyancy zone, whereby the plastic film residues rise to the liquid surface. At rest - or from the outflow zone, flow is redirected, preferably in a downward direction, and includes the woven fabrics and their residues, whereby the liquid phase from both zones is removed, preferably by means of a bottom outlet. The floating plastic film residues are removed from the liquid surface and fed as a clean product into the plastic recovery.

The flow speed and direction at rest - respectively the deposition zone is set so low that the floating plastic film residues are not carried further, but remain on the liquid surface.

In the following, the invention will be described with the help of an embodiment with reference to the drawing, in which the part of a processing according to the invention, from pre-sorted paper/plastic fractions from a waste processing plant, aimed at extracting plastic film residues, is indicated schematically.

The paper/plastic fraction, which is usually pressed into balls, is dissolved in a pulper, called pulp dissolver 1, with process water that is circulated. The paper pulp obtained is removed via the hole sieve and goes to paper recycling; the plastic foils are brought together with other contaminants as sifted residue, as they are formed, from the pulper 1, rinsed out in particular, whereby a brief mass formation is carried out appropriately after the addition of water, and fed by means of transport spirals into a step drum 2. The step drum 2 is an ordinary perforated drum, through whose holes on the one hand heavy substances, such as glass, metal, stones, etc., and on the other hand fibrous and floating substances such as process water containing entrained paper, exit and are collected in a device arranged below the step drum 2 collection container 3. Hereby, the liquid level in the collection container 3 can be selected in such a way that the step drum partially dives into it; in this way, a good washing-out effect is achieved. The water is returned from the collection tank 3 as process water in the pulper 1, the heavy substances are brought out by means of a screw conveyor 4 and collected as waste. The step drum 2 has a central outlet and the processed material containing the plastic films is subjected to water removal in a screw press 5, and divided in a pre-divider 6 to approx. palm size. The previously divided material then enters a (flotation/deposition) separation cup 7, where larger sinkable substances are separated. These are especially metal parts, non-finely divided textiles, PVC and other sinkable hard plastic parts, leather, etc. To improve the separation, stirrers or other devices that produce turbulence can also be used here. The portions that sink are brought out by means of bottom opening 8; the floating parts, to which the plastic film residues belong, are removed from the liquid surface with the help of an oar device 9, and when they enter a fine distribution device 10, which is preferably designed as a wet mill, in this the material is crushed to approximately the size of a fingernail. The finely divided material enters a gravity flotation beaker 11, which is supplied with finely divided material and process water from above. The transport of the finely divided material to gravity-force t-f Iota's ion beaker 11 takes place with the aid of an auger 12, in which the contamination parts are loosened.

The material is fed into the gravity flotation beaker 11, together with process water, in the direction of gravity downwards and fed out centrally at the bottom of the beaker; light parts such as wood and plastic foam, e.g. polystyrene foam, rises and is removed from the liquid surface.

The process water with the entrained plastic film residues is then pumped by means of a pump 13 into a flow-flotation cup 14 through an inlet 15 on the side, whereby a horizontal flow is formed. A dividing wall 16 in the flow-f Iotas ion cup 14 serves on the one hand to redirect the flow and on the other side to divide into a flotation zone with sedimentation funnel 17, and a resting or deposition zone 18. The plastic film residues carried by the liquid stream float up; the process water, which still contains liquids and contaminants, is pumped off through a bottom outlet 19. Part of the process water is led away from the sedimentation funnel in the upwelling zone by means of chute 22, and is supplied together with the other part of the liquid phase to the arch screen 24.

The floating plastic foil residues are transported from the floating zone, in which the flow is directed along the liquid surface, possibly with support using process water jets from a jet device 20 at the liquid surface, into the rest zone, and are removed there using a vein outlet 21. The plastic foil residues are now practically free of contaminants and fed to a regular recycling plant, where they are usually processed into a plastic granulate. Purities of over 97$ are achieved.

In the rest and deposition zone 18, the flow which is originally directed along the liquid surface is redirected in a downward direction; the flow thus carries all floating and sinkable parts, especially textile fibers and woven remnants of plastic fabric, downwards to outlet 19; the liquid phase is pumped with the aid of a pump 23 to an arc sieve 26, and is then freed from the solids. The solids go together with those from the bottom outlet 18 in the separation beaker 7, and those removed from the surface in the gravity flotation beaker 11 to a screw press 25, and after densification and removal of water are removed as waste fraction.

The process water from the bow screen 24 is led via a pump 26 into a collecting container 27 and is returned there on one side to the wet mill 10, and on the other side to the gravity flotation cup 11.

The process water from the fiber preparation, the screw press 5, the separation cup 7, the auger 12 and the plastic preparation process enters a clarification plant with sludge dewatering and is returned in a prepared state to the pulp dissolver 1, to the wet mill 10, to the jet nozzle device 20, to the plastic preparation process and to the fiber preparation process.

The flowchart also recognizes common, not mentioned in detail, common transport devices, such as pumps, belt and screw conveyors, as well as sluices, valves and control devices.

The invention further comprises a device for sorting out mixed waste, such as rubbish or fractions thereof, for the separate recycling of on the one hand paper and on the other hand plastic film materials, especially in recycling facilities, characterized by the fact that it comprises a pulp solver (pulpers) for the treatment of a pre-sorted fraction containing paper and plastic foils, a liquid removal device, in particular a hole drum, for the screening residue that is brought out of the pulp solver, a division device, possibly with a pre-connected thickener, for the filter residue that has been processed in the liquid removal device, as well as at least one solid/liquid separation device, in particular a flotation container, for separating the plastic film residues as the upper phase.

Further features of the device according to the invention, which can be provided alone or in combination, are the following: It comprises a sifting drum which partially dips into a washing or slurry bath.

In addition to the comminution device for the dewatered sifting residue, a flotation/deposition beaker is provided for re-slurrying the sifting residue and for separating heavy substances such as stones, metal parts, hard plastic parts etc.

In connection with the floating/settling beaker, a comminution device has been provided, possibly with a connected dewatering condenser, for the re-slurried sifting residue.

In front of the solid/liquid separation device for separating the plastic film residues, a gravity flotation cup is connected for the separation of flowable, light parts such as wood or foam plastic, especially polystyrene foam, with the exception of plastic film residues.

As a solid/liquid separation device for separating the plastic film residues, a flow flotation beaker has been provided, in which the plastic film residues under the influence of flow are present as the upper phase, whereby an execution device for the plastic film residues has been provided in the area of the liquid mirror in the flow flotation beaker.

In the flow-flotation cup, an inlet area is provided in which at least one inlet is arranged, as well as possibly flow guiding devices, so that a flotation zone is formed, in which at least an essentially horizontally directed liquid flow can be formed.

A flow diverting device is provided in the form of a cup partition, which separates the buoyancy zone from a rest and deposition zone.

The flow-flotation cup exhibits in the rest and deposition zone a liquid drain which runs at least substantially in the direction of gravity.

The invention is not limited to the specified embodiment. Consequently, e.g. another process water recovery possible, and different transport devices can be omitted, such as e.g. the propeller 12, so that the gravity flotation beaker 1 is placed directly above the wet mill 10, as well as the wet mill directly above the outlet from the buoyancy/deposition beaker 7.

Particularly advantageously, as mentioned at the outset, the invention can be used in combination with a recycling plant where there is already a fiber wet sorting.

Claims (16)

1. Process for the sorting of mixed waste, such as rubbish or fractions thereof, for the recycling of plastics, especially in recycling facilities, whereby a pre-sorted fraction containing plastic foils is processed in a pulper (pulpers), the obtained, especially paper-containing suspension is removed by means of sieves, and the contamination phase, which constitutes the sifting residue, containing plastic foil is deposited, characterized in that for the extraction of the plastic portion a sifting residue of the contamination phase is collected, the sifting residue is fed out from the mass dissolver (1), crushed after removal of liquid and then the plastic foil portion is separated from a liquid phase. 2. Method according to claim 1, characterized in that liquid is removed from the sifting residue which has been brought out from the mass dissolver (1) in a hole drum (2). 3. Method according to claim 2, characterized in that liquid is removed from the sifting residue which has been brought out by the mass dissolver (1) in a hole drum (2), which partially sinks into a flotation liquid bath (3). 4. Method according to one of claims 1 to 3, characterized in that the dewatered and finely divided screening residue is freed of heavy substances in a settling container (7). 5. Method according to one of the claims 1 to 4, characterized in that the dewatered and finely divided screening residue, especially after separation of heavy substances and preferably after a further fine division, is freed from lifters, light portions, such as wood or foam plastic, especially polystyrene foam, with the exception of plastic film residues, in a gravity-force t-f lotation beaker (11). 6. Method according to one of claims 1 to 5, characterized in that the dewatered and finely divided sieve residue is processed in a flow-flotation beaker (14) in which the plastic film residues under the influence of flow rise to the liquid surface and are removed there. 7. Method according to claim 6, characterized in that a flotation zone (18) is provided in the flow-flotation cup (14), in which an at least substantially horizontally directed liquid flow is maintained and rapidly sinking contaminants can be separated through a sedimentation funnel (19). 8. Device for sorting mixed waste, such as rubbish or fractions thereof, for separate recycling of on the one hand paper and on the other hand plastic film materials, especially in recycling facilities, characterized in that it comprises a pulp solver (1) (pulps) for processing a pre-sorted fraction containing paper and plastic foils, a liquid removal device (2), especially a perforated drum, for the screening residue brought out by the pulp solver (1), a dividing device (6), possibly with a pre-connected thickener (5), for the filter residue that is processed in the liquid removal device ( 2), as well as at least one solid/liquid separation device, in particular a flotation container (14), for separating the plastic film residues as the upper phase. 9. Device according to claim 8, characterized by providing a sifting drum (2) which partially dives into a washing or slurry bath (3). 10. Device according to claim 8 or 9, characterized in that, in connection with the comminution device (6) for the dewatered screening residue, a floatation/deposition beaker (7) is arranged for a slurry of the screening residue and for separating heavy substances such as stones, metal parts, hard plastic parts etc. 11. Device according to claim 10, characterized in that a comminution device (10), optionally with a pre-connected dewatering condenser, is arranged in connection with the floating/deposition beaker (7) for the re-slurried sifting residue. 12. Device according to one of claims 8 to 11, characterized in that a gravity flotation cup (11) is connected in front of the solid/liquid separation device (14) for separating the plastic film residues for separating floatable, light parts, such as wood or foam plastic, especially polystyrene foam, with the exception of plastic film residues. 13. Device according to one of claims 8 to 12, characterized in that a flow flotation beaker is provided as a solid/liquid separation device (14) for separating the plastic film residues, in which the plastic film residues under the influence of flow are present as the upper phase, whereby an output device (21) for the plastic film residues is arranged in the area of the liquid mirror for the flow-f Iotas ion beaker. 14. Device according to claim 13, characterized in that in the flow flotation cup (14) an inlet area is provided in which at least one inlet (17) and possibly flow control devices (16) are arranged in such a way that a flotation zone (18) is formed, in which an at least substantially horizontally directed fluid flow can be provided. 15. Device according to claim 14, characterized in that a flow control device is provided in the form of a cup intermediate wall (16) which separates the upwelling zone (18) from a resting and settling zone (17). 16. Device according to one of the claims 13 to 15, characterized in that the flow-flotation cup (14) in the rest and deposition zone (17) exhibits a liquid drain proceeding at least essentially in the direction of gravity.