GB2428986A

GB2428986A - A waste recycling system

Info

Publication number: GB2428986A
Application number: GB0516294A
Authority: GB
Inventors: Jonathan Paul Blake; David John Evans
Original assignee: RACOON GROUP Ltd
Current assignee: RACOON GROUP Ltd
Priority date: 2005-08-09
Filing date: 2005-08-09
Publication date: 2007-02-14
Also published as: GB0516294D0

Abstract

A waste recycling system for recycling items comprising metal and non-metal components has means (15) in the form of a hammer mill (15) for fragmenting the item into a mixture of metal and non-metal fragments, separator means (70, 60 95, 100, 115,) for separating the fragments into a metal fraction and a non-metal fraction, and means for collecting the individual fractions. The metal or metal-containing fragments (21b) are separated and then divided into ferrous and non-ferrous metal fragments using a rare earth magnet (30). The invention also comprehends a method of recycling an item involving fragmentation of the item into particles, separation of the particles into metal and non-metal-containing components, and separating the metal components into ferrous and non-ferrous metals. An eddy current separator (50) may also be used for separating non-ferrous metals; a metal detector (110) identifies the components for separation. Size-separation of the non-metal fraction is achieved by means of a vortex (90) and fractionation of the non-metal fraction on the basis of colour is achieved by a colour separator (115). The items being recycled may be window frames.

Description

I

A WASTE RECYCLING SYSTEM

The present invention relates generally to a method of recycling an item and particularly to a method of recycling an item comprising metal and non-metal components.

Many items which are or have become waste comprise both metal and nonmetal components. As such, they may include useful amounts of materials which could be re-used if they could be liberated. For example, plastic window frames such as Pvc (poly vinyl chloride) window frames include large amounts of plastics material which could be re-used and also include metal components, such as locking mechanisms, which could also be re-used if separated from the non-metal components. One alternative to recycling such items is to bury them in land-fill sites, which is wasteful.

According to a first aspect of the present invention there is provided a method of recycling an item comprising metal and non-metal components, comprising the steps of: fragmenting the item; and separating the fragments into a metal fraction and a non-metal fraction.

The present invention therefore comprises an automated recycling method using an item with metal and non-metal components as its substrate and includes a fragmentation step in which metal and non-metal fragments can be liberated, followed by a separation step in which metal and non-metal fractions are readied for further processing.

The fragmentation step may comprise smashing the item and this may be achieved by passing the item through a hammer mill.

The metal-containing fragments may be separated from the non-metal fragments using a rare earth magnet. High intensity rare earth magnets (such as those available from Magnapower Limited) can be used when a maximum level of metal removal is required. Accordingly, fragments comprising metal and both metal and non-metal material will be separated from those comprising just non-metal material. The result is that the nonmetal fraction may contain little contamination from metal material whereas the metal fraction may include fragments with both metal and nonmetal in the same fragment in addition to pure metal fragments.

The initial separation step to form the metal and non-metal fractions may be relatively crude because fragments containing both metal and non-metal on the same fragment may be generated and be separated into the metal fraction. The term "metal fraction" therefore means that fraction containing fragments which comprise or include metal material following the initial separation step. The "purity" of the non-metal fraction is therefore likely to be higher than the metal fraction. Further processing steps may be employed in order to increase the purity of the metal fraction such as a further fragmentation step followed by a further separation step.

The method may further comprise the step of separating ferrous and nonferrous metals from the metal fraction.

The ferrous metal fragments may be separated using a magnet. A ferrite magnet with an alternating pole or a continuous pole may be used. A deep field magnet system (such as one available from Magnapower Limited) may be used to penetrate within a mass of fragments in order to extract the maximum amount of ferrous material. The magnet may be used to remove only substantially pure ferrous metal fragments (i.e with little or no nonmetal material) or to remove both pure metal and metal/non-metal fragments.

Non-ferrous metals may be separated using an eddy current separator. The separator may be used to remove only substantially pure non-ferrous metal fragments (i.e with little or no non-metal material) or to remove both pure non- ferrous metal and non-ferrous metal/non-metal fragments.

Once the metal and non-metal fractions have been separated the non-metal fraction may be subjected to a metal detection step to allow removal of un-separated metal or metal-containing fragments.

In a further processing step to facilitate recovery and recycling the nonmetal fraction may be granulated.

In order to prevent coagulation of the non-metal granules the granular product may be subjected to a static elimination step.

The granulated product may be size separated by passing it through an air vortex.

This may allow for separation of dust and small particles.

In order to ensure purity of the non-metal fraction the granulated product may be subjected to a metal detection step.

The granulated product may be subjected to a colour separation step. Colour separation may be effected by a colour separator such as an electronic or optical colour sorting machine (available from Sortex Ltd).

The colour separation step may comprise separating white granules from the remaining granulated product.

The fragmentation step may be preceded by a cleaning step in which the item is cleaned in preparation for recycling. In this step components which are unsuitable for recycling or are to be recycled elsewhere can be removed.

The item may be a window frame. The window frame may include plastics and/or wood material. The window frame may also include ferrous and/or non-ferrous metal components in the form of, for example, locking or opening mechanisms.

The fragmentation step may be preceded by the step of removing the or each window pane from the window frame.

The present invention also provides a plastic window frame recycling method comprising a method as described herein.

The present invention also provides apparatus for recycling an item comprising metal and non-metal components, the apparatus comprising: means for fragmenting the item; and means for separating the item fragments into a metal fraction and a non-metal fraction.

The fragmentation means may comprise a hammer mill which smashes the item into pieces.

The separation means may comprise a rare earth magnet which removes metal (ferrous and non-ferrous) material from the mass of fragments.

The apparatus may further comprise means for separating ferrous and nonferrous metals from the metal fraction. The separation means may comprise a magnet for separating or extracting ferrous metals. The separation means may comprise an eddy current separator for separating or extracting non-ferrous metals.

The apparatus may further comprise a metal detector for detecting unseparated metal fragments in the non-metal fraction.

The apparatus may further comprise a granulator for granulating the nonmetal fraction.

The apparatus may further comprise means for eliminating static from the granulated non-metal fraction.

The apparatus may further comprise an air vortex or an air declassifier for size- separation of the granulated non-metal fraction.

The apparatus may further comprise a secondary metal detector for detecting metal in the granulated non-metal fraction.

The apparatus may further comprise colour separation means for fractionating the granulated non-metal fraction on the basis of its colour.

The colour separation means may separate white granules from the granulated non- metal fraction.

One possible recycling process conducted in accordance with the present invention is as follows.

An item or a group of items to be recycled are placed onto a conveyor belt. The item/s comprise metal material and non-metal material in the form of plastics material. The conveyor belt transfers the item/s to a hammer mill. At the hammer mill the item/s are smashed into small pieces. The fragments resulting from the hammer mill will comprise: 1) fragments containing only metal; 2) fragments containing only non-metal; and 3) fragments containing both metal and non-metal.

A hammer mill or the like rather than, for example, a shredder is preferred because a hammer mill tends to smash and separate components rather than to draw the separated material together as is the case with a shredder or the like.

The fragments passing out of the hammer mill drop onto a conveyor belt which passes through a rare earth separator. High intensity rare earth magnets can be used to give a maximum level of metal removal. The rare earth separator removes both metal-only "pure" fragments and metalonly/non-metal "hybrid" fragments.

The metal-containing fraction is then subjected to a ferrous metal extraction step in which a deep field magnet system is used. The sensitivity of the magnet system could be set so that only ferrous metalonly fragments are recovered whereas hybrid fragments including both ferrous metal and non-metal material may be left; alternatively all ferrous fragments, whether pure or hybrid, may be extracted.

The remaining material of the metal fraction may be subjected to an eddy current separator. The eddy current separator removes non-ferrous metal fragments.

Again, the sensitivity of the eddy current separator may be such that only substantially pure non-ferrous metal fragments are removed or such that hybrid non-ferrous metal/non-metal fragments are also separated.

The result of this metal recovery phase is a ferrous fraction and a nonferrous fraction. The ferrous and non-ferrous fractions may be substantially pure in that any fragments containing both metal and nonmetal material may have been excluded. The ferrous and non-ferrous fractions may be delivered to suitable receptacles. In the event that hybrid fragments are excluded these may be delivered to a further receptacle. The ferrous, non-ferrous and optionally ferrous hybrid and non-ferrous hybrid fractions may then be subject to further processing and recovery steps.

The non-metal fraction comprises plastics material and is discharged into a further receptacle.

The non-metal fraction is fed onto a conveyor belt which transports the fragments to a vibrating screening table and the fragments fall through the table onto a conveyor belt. The fragments are passed through a metal detector and if any metal is detected the conveyor belt is stopped so that any metal can be removed (for

example by hand).

The fragments then drop into a granulator which forms granulated plastics material.

The granulated plastics material then passes into a primary air vortex which is capable of size separation. The vortex is calibrated to separate dust and small particles for disposal.

The main granular product is passed through a static eliminator before being fed into a secondary air vortex to separate any remaining dust and small particles. The resulting plastics material is subjected to a metal detection step as it is transported on a conveyor belt. The conveyor belt stops if metal is detected so that it can be removed.

The granulated plastics material is then subjected to a colour separation step. A colour separator is used and identifies coloured particulate material. Accordingly non-white material can be separated from white material. As a result white granulated plastics material can be separated.

The present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a window suitable to be recycled by a method according to the present invention; Figure 2 is a plan view of the window shown in Figure 1 following an initial preparation step; Figure 3 is a side view of apparatus forming part of a first recycling phase according to the present invention; Figure 4 is a side view of a hammer mill formed as part of the apparatus of the present invention; Figure 5 illustrates a rare earth separator formed according to the present invention; Figure 6 illustrates a magnet separator formed according to the present invention; Figure 7 illustrates an eddy current separator formed according to the present invention; and Figure 8 is a schematic illustration of apparatus for recycling non-metal material forming part of the recycling apparatus of the present invention.

Referring first to Figure 1 there is shown a window generally indicated 1. The window 1 comprises a window frame 2 which houses four square glass window panes 3.

The frame 2 comprises a square perimetral frame 4 with cross members 5, 6 spanning between opposite sides of the perimetral frame 4 to divide it into four square openings for receiving the panes 3.

The perimetral frame 4 and cross members 5, 6 comprise casings made of plastics material which incorporate components such as locking mechanisms, opening mechanisms and structural strengthening members (not shown). The window 2 therefore comprises a mixture of metal and non-metal material.

The window 2 may also comprise other materials such as rubber sealing strips and mastic.

In order to prepare the window 2 for recycling the glass panes 3 are removed. The panes 3 may be recycled on-site as part of the recycling system of the present invention or may be transported off-site to a specialised glass recycling facility. In addition, the window 2 is cleaned of any rubber sealing strips and sealant used around the panes 3 to leave the frame 2 as shown in Figure 2 in which what remains is the perimetral frame 4 and cross members 5, 6. Accordingly, the frame 2 shown in Figure 2 comprises only metal and plastics components.

Referring now to Figure 3, cleaned frames 2 of the type shown in Figure 2 are loaded onto a conveyor belt 10 which transports the frames 2 to a hammer mill 15.

Referring now also to Figure 4, the hammer mill 15 will be well known to those skilled in the art and will not be described in great detail herein. The frame 2 is smashed by one or more hammer members 16 into fragments 20. The fragments may comprise only metal, only plastics, or a combination of metal and plastics.

Ideally the fragments 20 will comprise either only metal or only plastics. Further fragmentation steps may therefore be included in order to improve the liberation of plastics and metal material from the frame 2.

Referring now to Figure 5, the fragments 20 are fed onto a conveyor belt 25. The fragments 20 comprise metal fragments 21 (indicated by hatched lines) and plastics fragments 22.

The fragments 21, 22 are transported along the conveyor 25 until the conveyor 25 passes around a rare earth drum magnet 30.

The magnet 30 attracts metal (both ferrous and non-ferrous) so that as the fragments 21, 22 pass around the magnet 30 on the conveyor 25 only the metal fragments 21 are attracted to the magnet 30; the plastics fragments 22 are thrown off the conveyor 25 for collection. The metal fragments 21 remain attracted to the magnet until the conveyor 25 moves them beyond the attraction of the magnet 30 at which point the fragments 21 fall off the conveyor 25 under the action of gravity so that they can be collected. The result of the rare earth separator is therefore that the fragments 21, 22 are separated into a metal fraction and a non-metal fraction.

It is possible that in addition to pure metal and non-metal fragments there are hybrid fragments containing both metal and non-metal materials. The advantage of a rare earth separator system is that any hybrid fragments would be attracted by the magnet 30 so that as much metal as possible, whether it forms part of a pure fragment or a hybrid fragment is removed to give a non-metal plastics fraction with as little contaminating metal material as possible.

Referring now to Figure 6, the metal fraction resulting from the separation step shown in Figure 5 is transferred to a conveyor belt 35. The metal fraction comprises ferrous metal fragments 21 a (illustrated by hatched lines) and non- ferrous metal fragments 21b. A ferrite drum magnet 40 is positioned at one end of the conveyor 35 and functions in the same general way as the drum magnet 30 illustrated in Figure 5. Ferrous metal fragments 21 a are attracted onto the magnet as the conveyor 35 passes it and therefore non- ferrous fragments 21b are thrown off the conveyor whereas ferrous fragments 21 a remain on the conveyor until it passes the magnet 40 whereupon they drop off. In this way ferrous and non-ferrous metal fragments can be separated.

In this embodiment the sensitivity of the magnet 40 is such that only substantially pure ferrous fragments which are strongly magnetic are retained and thus separated from the remaining fragment. Accordingly, the fragments thrown off the conveyor 35 as it passes the magnet 40 may comprise non-ferrous metal fragments and also hybrid fragments which may be either non-ferrous metal/non-metal or ferrous metal/non-metal fragments.

Referring now to Figure 7, the non-ferrous fraction resulting from the separation procedure described in relation to Figure 6 is transported on a conveyor belt 45.

The fragments of the fraction comprise non-ferrous metal fragments 21b and also hybrid fragments comprising ferrous metal/non-metal fragments 23 and non- ferrous metal/non-metal fragments 24. The fragments 23 are illustrated by a single horizontal split line and the fragments 24 are illustrated by a single vertical split line. The fragments 21b, 23, 24 are transported to an eddy current separator 50 which is calibrated to attract non-ferrous fragments but not either of the hybrid fragments 23, 24. Accordingly, when the conveyor belt moves the fragments 21b, 23, 24 pass the separator 50 the hybrid fragments 23, 24 are thrown off the conveyor and the non-ferrous metal fragments 21 b are retained and then released.

The result of the separation steps described in relation to Figures 5, 6 and 7 is that a metal fraction and a non-metal fraction are first produced and the metal fraction is then sub-divided into ferrous metal fragments, non-ferrous metal fragments, and a fraction containing both ferrous metal/non-metal and non-ferrous/non-metal hybrid fragments. Of course in other embodiments the separation steps shown in Figures 6 and 7 could be modified so that hybrid fragments could be separated together with pure fragments.

Referring now to Figure 8, there is illustrated apparatus for further processing of the plastics fragments 22 separated in the step shown in Figure 5.

The fragments 22 are fed onto a conveyor belt 55 at the end of which is positioned a vibrating screen table 60. The fragments 22 drop onto the table 60. The table 60 can serve to separate out the fragments 22 and could be set to restrict the size of fragments which can progress.

Fragments 22 falling through the table 60 drop onto a conveyor belt 65 which carries them under a metal detector 70. The detector 70 is linked to the conveyor belt 65 and if any metal is detected within the fragments 22 the belt 65 is stopped so that fragments comprising or including metal can be removed either manually by hand or automatically.

Fragments which successfully pass the detector 70 drop into a granulator 75. The product of the granulator 75 is granules of plastics material 80 and some dust and small particles 85 which are unwanted. The granules 80 and particles 85 are passed through an air vortex 90 which size separates the majority of the particles from the granules 80.

The granules 80 (and any remaining particles 85) are then subjected to a static elimination step by a static eliminator 95 and then onto a further air vortex 100 which removes any remaining dust and small particles 85 leaving plastics granules which drop onto a conveyor belt 105.

The granules 80 are passed under a secondary metal detector 110 which is linked to the conveyor belt 105. If any metal is detected amongst the particles 80 then the conveyor belt 105 is stopped so that the metal can be removed.

Granules 80 successfully passing the metal detector 110 are then passed through a colour separator 115 which can distinguish between non-white (i. e. coloured) and white granules 80. The granules 80 are separated on the basis of whether they are coloured or non-coloured with coloured granules sorted into a first receptacle 120 and white granules sorted into a secondary receptacle 125.

Claims

1. A method of recycling an item comprising metal and non-metal components, comprising the steps of: - fragmenting the item; and separating the fragments into a metal fraction and a non-metal fraction.

2. A method as claimed in Claim 1, in which the fragmentation step comprises smashing the item.

3. A method as claimed in Claim 1 or Claim 2, in which the fragmentation step comprises passing the item through a hammer mill.

4. A method as claimed in any preceding Claim, in which metal-containing fragments are separated using a rare earth magnet.

5. A method as claimed in any preceding Claim, further comprising the step of separating ferrous and non-ferrous metals from the metal fraction.

6. A method as claimed in Claim 5, in which ferrous metals are separated using a magnet.

7. A method as claimed in Claim 5 or Claim 6, in which non-ferrous metals are separated using an eddy current separator.

8. A method as claimed in any preceding Claim, in which the non-metal fraction is subjected to a metal detection step to allow removal of unseparated metal fragments.

9. A method as claimed in any preceding Claim, in which the non-metal fraction is granulated.

10. A method as claimed in Claim 9, in which the granular product is subjected to a static elimination step.

11. A method as claimed in Claim 9 or Claim 10, in which the granulated product is passed through an air vortex.

12. A method as claimed in any of Claims 9 to 11, in which the granulated product is subjected to a metal detection step.

13. A method as claimed in any of Claims 9 to 12, in which the granulated product is subjected to a colour separation step.

14. A method as claimed in Claim 13, in which the colour separation step comprises separating white granules from the granulated product.

15. A method as claimed in any preceding Claim, in which the fragmentation step is preceded by a cleaning step in which the item is cleaned.

16. A method as claimed in any preceding Claim, in which the item is a window frame.

17. A method as claimed in Claim 16, in which the fragmentation step is preceded by the step of removing the or each window pane from the window frame.

18. A method as claimed in Claim 16 or Claim 17, in which the window frame includes plastics material.

19. A method as claimed in Claim 16 or Claim 17, in which the window frame includes wood.

20. A plastic window frame recycling method comprising a method as claimed in any preceding Claim.

21. Apparatus for recycling an item comprising metal and non-metal components, the apparatus comprising: - means for fragmenting the item; and - means for separating the item fragments into a metal fraction and a non- metal fraction.

22. Apparatus as claimed in Claim 21, in which the fragmentation means comprise a hammer mill.

23. Apparatus as claimed in Claim 21 or Claim 22, in which the separation means comprise a rare earth magnet.

24. Apparatus as claimed in any of Claims 21 to 23, further comprising means for separating ferrous and non-ferrous metals from the metal fraction.

25. Apparatus as claimed in Claim 24, in which the separation means comprise a magnet for separating ferrous metals.

26. Apparatus as claimed in Claim 24 or Claim 25, in which the separation means comprise an eddy current separator for separating non-ferrous metals.

27. Apparatus as claimed in any of Claims 21 to 26, further comprising a metal detector for detecting un-separated metal fragments in the nonmetal fraction.

28. Apparatus as claimed in any of Claims 21 to 27, further comprising a granulator for granulating the non-metal fraction.

29. Apparatus as claimed in Claim 28 further comprising means for eliminating static from the granulated non-metal fraction.

30. Apparatus as claimed in Claim 28 or Claim 29, further comprising an air vortex for size-separation of the granulated non-metal fraction.

31. Apparatus as claimed in any of Claims 28 to 30, further comprising a secondary metal detector for detecting metal in the granulated non-metal fraction.

32. Apparatus as claimed in any of Claims 28 to 31, further comprising colour separation means for fractionating the granulated non-metal fraction on the basis of its colour.

33. Apparatus as claimed in Claim 32, in which the colour separation means separates white granules from the granulated non-metal fraction.

34. A method substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

35. Apparatus substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.