WO2009068874A2

WO2009068874A2 - Method of and apparatus for reducing a vehicle tyre into components for re-use and recycling

Info

Publication number: WO2009068874A2
Application number: PCT/GB2008/003950
Authority: WO
Inventors: Donald Charles Blair; Michael Frederick Nobbs
Original assignee: Aquablast Limited
Priority date: 2007-11-28
Filing date: 2008-11-27
Publication date: 2009-06-04
Also published as: GB0723303D0; WO2009068874A3

Abstract

The method of the invention involves the stepwise reduction of a vehicle tyre (T), having a tread portion (18) supporting tread lugs (14) and sidewall portions (17) connecting the tread portion or band (18) to rim-engaging beads (24), into useable constituent parts. The methods of the invention are achieved using high-pressure water jets (12, 22, 32, 52) to remove tread lugs and pattern from the tread portion of a tyre, to cut rim-engaging beads from each side wall of the tyre and to remove the sidewall portion to leave a strip of tread material. Each removed portion is further reduced at processing stations (30, 40, 50) to separate rubber material from reinforcing material. Apparatus for effecting the methods of the invention are also disclosed.

Description

METHOD OF AND APPARATUS FOR REDUCING A VEHICLE TYRE INTO COMPONENTS FOR RE USE AND RECYCLING

Field of the Invention

The present invention relates to a method of and apparatus for reducing a vehicle tyre into components for re-use and recycling. The invention is directed particularly to a method of and apparatus for obtaining commercially valuable materials from vehicle tyres that have been expended past their primary or secondary use and to do so in an economically efficient and substantially environmentally friendly manner.

The method and apparatus as described hereinbelow are directed primarily with reference to the recovery of materials from vehicle tyres or conveyor belts, such as rubber crumb, high-tensile steel, metal mesh material and ancillary materials used in the construction thereof. It will be appreciated by the skilled addressee that the invention may be applied to any composite article having reinforcing material constrained within a rubber or elastomeric matrix

Background to the Invention

There are well-established problems associated with the disposal of used tyres, most significant being the space they occupy in landfill sites (and ancillary problems which have lead to a ban on using landfill sites as a disposal option in many jurisdictions) and in the unsightly and dangerous stockpiles of tyres often seen in or adjacent to larger cities. A significant hazard is that posed by fires (often started maliciously) which are notoriously difficult to extinguish and release thick toxic smoke into the surrounding air. Additionally, tied up within the tyres is a considerable investment of valuable resource material which is otherwise wasted. It is estimated that the calorific equivalent of 5 and 15 litres of fuel oil is locked within a standard road vehicle and a commercial vehicle tyre, respectively.

Within the last twenty years, and more particularly within the last decade, there has been a considerable upsurge in interest from commercial undertakings and impetus from government bodies to seek environmentally friendly solutions to problems such as the "tyre mountain".

In the past, suggested solutions have included shredding tyres prior to placement in landfill sites, using the types as a fuel element in power generation (and the resulting ash in cementatious products) and coastal erosion barriers, either for onshore placement or offshore as artificial reefs.

As noted above, free burning of tyres released toxic gases and thick smoke in addition to a tarry oil. At significantly higher temperatures, tyre rubber can be an excellent fuel source, however, there remain problems with some released gases and the reinforcement within the tyre. There have been suggested pyrolytic techniques to overcome this particular scenario but most prior art solutions tend towards the separation of wire reinforcement and rubber material. There are many examples of physical separation method and some suggest the use of nitrogen baths to render the rubber more brittle to extract the wire reinforcement within.

Many of the above solutions have now been discredited as environmentally unsafe or too expensive to implement.

Due to the perceived value of rubber crumb material as a staple commercial product and it's wide range of uses, there is a financially convincing argument that graded rubber crumb ought to be recovered from the existing and growing stockpile of waste tyres. A number of suggestions have been put forward in the patent literature for extracting high-grade rubber crumb from vehicle tyres.

It is a primary object of the present invention to provide a method of reducing a vehicle tyre which obviates the disadvantages associated with the prior art and seeks to maximise the extraction of commercially viable materials therefrom in an economically efficient and substantially environmentally friendly manner.

It is a particular object of the present invention to obviate the disadvantages associated with methods of shredding tyres using cutting knives or teeth.

An additional object of the invention is to provide apparatus to implement the method of the invention and to extract commercially viable materials from waste tyres, conveyor belts and the like.

Summary of the Invention

Accordingly, the present invention provides a method of reducing a vehicle tyre, having a tread portion supporting tread lugs or a tread pattern and sidewall portions connecting the tread portion to rim-engagable beads, to useable constituent parts using high-pressure water jets, the method comprising:

removing tread lugs and pattern from the tread portion of a tyre;

cutting the rim-engaging beads from each sidewall of the tyre;

cutting the sidewalls from the tread portion of the tyre;

forming a strip of tread material by cutting across the width of the tread portion; and

feeding the strip into a material removal station to remove rubber from the treat portion thereof.

Advantageously, the method includes retaining a perimeter of tread material on the strip so as to fix reinforcing material within the framed strip.

The method further includes the separation of rubber and fabric from effluent water generated during the reduction of vehicle tyres, the method comprising; pumping rubber crumb slurry to a separation tank to extract a majority of effluent water;

feeding wet crumb to a press, where further water is extracted

conveying, from a damp crumb accumulator, a batch of damp crumb; and

feeding the damp crumb into a dryer unit.

Advantageously, the method further includes screening dry crumb to size.

In an alternative aspect of the present invention, there is provided a method of recovering tread lugs from a disused tyre, the method comprising:

positioning a tyre in a tyre rotation means so as to expose the tread lugs thereon to a pressurised water j et;

moving the jet along a tread lug so as to expose the lug surface to the directed jet;

rotating an array of nozzles comprising the jet across said tread surface to enhance a cutting action;

moving the nozzle with respect to successive tread lugs; and

rotating the tyre so as to position the nozzle at the start position of a successive tread lug,

whereby successive tread lugs are removed from the tyre until a substantially bald tyre having no tread pattern remains, the bald tyre being removed for subsequent processing.

Advantageously, the subsequent processing may include further reduction of the tyre to its constituent materials or selecting the tyre for subsequent re-treading. In the method above, the treated bald tyre suffers no damage to the reinforcement thereof and the integrity of the tyre remains.

Conveniently, a slurry of tyre tread pieces and rubber crumb is collected and conveyed to a crumb processing station.

In a second alternative aspect of the present invention, there is provided a method of removing a rim-engagable bead and a sidewall portion of a vehicle tyre, the method comprising:

positioning a tyre in a tyre rotation means adjacent a first fixed position pressurised cutting water jet;

rotating the tyre with respect to the jet so as to facilitate cutting of the rim- engagable bead portion from the sidewall portion of the tyre;

activating a second pressurised cutting water jet so as to facilitating cutting of the sidewall portion of the tyre from the tread portion thereof; and

duplicating the bead and sidewall portion cutting on a second side of the tyre

whereby an annular tread band is produced and is available for subsequent processing.

Preferably, both bead portions and both sidewall portions are removed sequentially but substantially simultaneously.

Conveniently, the second pressurised cutting jet is angularly offset and radially disposed from the first bead cutting jet.

In a third alternative aspect of the present invention, there is provided a method of reducing a tread band of a vehicle tyre, the method comprising:

cutting the tread band laterally using a pressurised abrasive cutting water jet to form an elongate tread strip; and feeding the strip past a rotating nozzle array, the nozzle array being adapted to move laterally across the band removing tread material from the strip.

Preferably, a perimeter of material is retained about the band to prevent reinforcing material constrained within the material matrix from releasing therefrom and fouling machinery.

The present invention also provides an apparatus for reducing a vehicle tyre, the vehicle tyre having a tread portion supporting tread lugs or a tread pattern and sidewall portions connecting the tread portion to rim-engagable beads, to useable constituent parts using high-pressure water jets, the apparatus comprising:

water jet means for removing tread lugs and/or pattern from the tread portion of a tyre;

programmable control means for positioning the water jet means;

water jet means for cutting the rim-engaging beads from each sidewall of the tyre;

water jet means for cutting the sidewalls from the tread portion of the tyre;

means for removing a strip of tread material by cutting across the width of the tread portion; and

means for conveying the strip into a material removal station to remove rubber from the treat portion thereof.

The apparatus further comprises means for separating rubber and fabric from effluent water generated during the reduction of vehicle tyres, the apparatus comprising;

a separation tank to extract a majority of effluent water from a rubber crumb slurry presented thereto; a press where further water is extracted from wet crumb from the separation tank;

a damp crumb accumulator from which there is conveyed a batch of damp crumb for feeding to a dryer unit.

Advantageously, the apparatus further includes screening means for separating dry crumb according to size.

The present invention also provides a number of intermediate apparatus having separate commercial lives, including an apparatus for recovering tread lugs from a disused tyre, the apparatus comprising:

a tyre rotation means for positioning a tyre so as to expose the tread lugs thereon to a pressurised water jet;

programmable control means for positioning the water jet means along a tread lug so as to expose the lug surface to the directed jet; and

means for rotating an array of nozzles of said water jet means across said tread surface to enhance a cutting action;

Conveniently, the apparatus includes a means for collecting and conveying a slurry of tyre tread pieces and rubber crumb downstream to a crumb processing station.

In a further alternative aspect of the present invention, there is provided a rim- engagable bead and a sidewall removal station, the station comprising: a tyre rotation means for positioning a tyre adjacent a first fixed position pressurised cutting water jet and rotating said tyre so as to facilitate cutting of the rim-engagable bead portion from the sidewall portion of the tyre;

a second pressurised cutting water jet positioned so as to facilitating cutting of the sidewall portion of the tyre from the tread portion thereof.

Conveniently, the station includes means for duplicating the bead and sidewall portion cutting on a second side of the tyre whereby an annular tread band is produced and is available for subsequent processing.

The present invention yet further provides a tread band reducing station, the station comprising:

pressurised abrasive cutting water jet for cutting the tread band laterally to form an elongate tread strip; and

conveying means for feeding the strip past a rotating nozzle array, the nozzle array being adapted to move laterally across the band removing tread material from the strip.

Brief Description of the Drawings

The invention will now be described more particularly with reference to the accompanying drawings which show, by way of example only, constructions of a tread lug removal means, bead and sidewall removal means and associated bead cleaning station and sidewall processing station, tread band cutting and processing stations and plant for the dewatering, drying and grading of rubber crumb, in accordance with the invention. In the drawings:

Figure 1 comprises perspective views of a tread lug removal means, bead and sidewall removal means and associated bead cleaning station and sidewall processing station, tread band cutting and processing stations; and

Figure 2 is a schematic perspective view of the plant for the dewatering, drying and grading of rubber crumb.

Detailed Description of the Drawings

In the present description, the terms "upstream" and "downstream" should be regarded with respect to the drawings only and relate to the processing and conveyance of tyres, tyre parts and constituent materials taken therefrom. In this arrangement, "upstream" represents the source of material to be processed and "downstream" towards an accumulation point for further processing, storage or dispatch.

The term "side walls", "beads", "tread band" and "tread lugs" are used conventionally to describe regions and portions of a tyre and should not in any way be considered limiting.

Referring now to the drawings, and initially to Figure 1 , an accumulated stock S of vehicle tyres T is presented for reducing into constituent components or useful commercial products. At a first processing station 10, the tyre T is secured for rotation sequentially past at least one tread lug removing nozzle 12, which is adapted under microprocessor control to follow the raised profile of an individual tread lug 14. Using a rotating nozzle 12 comprising an array of high-pressure jet outlets, the lug is eroded using high-pressure water (and optionally cutting grit) supplied via an ultra-high pressure compressor (not shown). Using edge-detecting sensors, the nozzle 12 is passed over the tread lug 12 until it is reduced to the same level as the surrounding flat lands 16 between each tread lug. The tyre is then rotated stepwise until the next lug is detected and the nozzle is moved to a start position at or towards the intersection of the tyre tread band and a sidewall 17 thereof. In this manner, successive tread lugs are cut from the tread band portion 18 of the tyre and the crumb slurry is collected.

On agricultural and construction vehicle tyres, the lugs are often widely spaced and have a very distinct profile with respect to the surrounding tread band portion lands and after removal of the lugs, there is significant tread rubber remaining. As the entire tread band is eroded (or roughed) to a degree where new tread lugs can be easily keyed to the tread band portion, the treated tyres are suited to a retreading process for subsequent re-use. Where re-treading and re-use is not viable, the treated tyre is passed to the next processing station as described hereinbelow. For standard automotive vehicles (where tread patterns are more complicated and re-treading may not be acceptable to the market) a more significant amount of tread and surrounding rubber material may be eroded at this initial stage.

At a second processing station 20, an abrasive water jet is applied via a cutting nozzle 22 to remove a rim-engaging portion 24 of the tyre from the tyre carcase T. The nozzle is fixed and the tyre is rotated with respect to the bead portion cutting nozzle 22. A sidewall cutting nozzle 26 is angularly offset and radially spaced from the bead cutting nozzle 22 to remove the sidewall portion 17 of the tyre. In a preferred construction of second processing station 20, bead and sidewall cutting nozzles 22,26 are provided on each side of the tyre so as to remove both bead portions simultaneously and similarly both sidewalls.

The bead portions 24 comprising high-tensile strength steel wire loops L or rings encased in rubber are either conveyed for dispatch or storage in that form or passed to a bead wire reclamation station 30 where tyre rubber is removed, again by high pressure water jet 32 rotated in situ to provide an enforced erosion action. Where the bead metal is provided as a series of successive loops of metal wire, the wire is uncoiled before being passed under the rotating nozzle 32, and is subsequently coiled again after remove of the rubber. Bare recovered wire coils are then stored or dispatched.

The sidewall portions 17 are conveyed to a sidewall processing station 40 where the sidewall is rotated past a further high pressure water nozzle adapted to move laterally across the presented face of the sidewall portion. Again, rubber crumb is collected as a slurry and radial reinforcing wire is recovered from the sidewall for reclamation.

The remaining tread band portion 18 of the tyre is cut using an abrasive water jet so as to form an elongate strip of rubber and reinforcing mesh. The elongate strip is fed, at a tread strip processing station 50 past a rotating nozzle comprising an array of jets, the nozzle being moved laterally across the width of the strip so as to erode successive areas of rubber from the underlying reinforcement.

In a preferred construction, the rubber is removed from the strip in a central area only, leaving a perimeter portion so as to prevent the reinforcing metal mesh from unravelling. These "framed" strips can be processed further or disposal of.

Referring now to Figure 2, downstream of the processing stations 10,20,30,40,50 there is provided a plant 60 for dewatering, drying and grading rubber crumb. The plant comprises a separation tank 61 into which a slurry of effluent water and rubber crumb is fed. Using a weir and trap system (although other systems are equally good) excess water is extracted and drained off, ideally for filtering and treating for re-use.

The wet crumb is pumped or otherwise conveyed to a filter belt press 62 where further water is extracted and the now merely damp crumb is accumulated in a storage vessel 64 to be fed batchwise into a rotary dryer 65 via a feed-screw 66. Hot air is circulated through the rotary dryer 65 via hot air inlet 67 and outlet 68 paths. Ideally, hot air is taken from the ultra-high pressure compressor so as to utilise this source more effectively. Drying crumb is agitated within the dryer by helical blades 69 disposed therein. To unload the dryer, it is rotated in the opposite direction to that used to load and dry crumb. The dried crumb is fed to a vibrating screen sorter 70 to grade the crumb and to feed the graded crumb into storage containers 72.

It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the appended claims.

Claims

CLAIMS:

1. A method of reducing a vehicle tyre, having a tread portion supporting tread lugs or a tread pattern and sidewall portions connecting the tread portion to rim-engagable beads, to useable constituent parts using high-pressure water jets, the method comprising:

removing tread lugs and pattern from the tread portion of a tyre; -

cutting the rim-engaging beads from each sidewall of the tyre;

cutting the sidewalls from the tread portion of the tyre;

2. A method of reducing a vehicle tyre as claimed in Claim 1, in which the method includes retaining a perimeter of tread material on the strip so as to fix reinforcing material within the framed strip.

3. A method of reducing a vehicle tyre as claimed in Claim 1 or Claim 2, in which the method includes the separation of rubber and fabric from effluent water generated during the reduction of vehicle tyres, wherein the method comprises;

pumping rubber crumb slurry to a separation tank to extract a majority of effluent water;

feeding wet crumb to a press, where further water is extracted

conveying, from a damp crumb accumulator, a batch of damp crumb; and

feeding the damp crumb into a dryer unit.

4. A method of reducing a vehicle tyre as claimed in Claim 3, in which the method includes screening dry crumb to size.

5. A method of recovering tread lugs from a disused tyre, the method comprising:

positioning a tyre in a tyre rotation means so as to expose the tread lugs thereon to a pressurised water jet;

moving the nozzle with respect to successive tread lugs; and

6. A method of recovering tread lugs as claimed in Claim 5, in which the subsequent processing includes further reduction of the tyre to its constituent materials or selecting the tyre for subsequent re-treading.

7. A method of recovering tread lugs as claimed in Claim 5 or Claim 6, in which a slurry of tyre tread pieces and rubber crumb is collected and conveyed to a crumb processing station.

8. A method of removing a rim-engagable bead and a sidewall portion of a vehicle tyre, the method comprising: positioning a tyre in a tyre rotation means adjacent a first fixed position pressurised cutting water jet;

duplicating the bead and sidewall portion cutting on a second side of the tyre

9. A method of removing a rim-engagable bead and a sidewall portion of a vehicle tyre as claimed in Claim 8, in which both bead portions and both sidewall portions are removed sequentially but substantially simultaneously.

10. A method of removing a rim-engagable bead and a sidewall portion of a vehicle tyre as claimed in Claim 8 or Claim 9, in which the second pressurised cutting jet is angularly offset and radially disposed from the first bead cutting jet.

11. A method for reducing a tread band of a vehicle tyre, the method comprising:

cutting the tread band laterally using a pressurised abrasive cutting water jet to form an elongate tread strip; and

feeding the strip past a rotating nozzle array, the nozzle array being adapted to move laterally across the band removing tread material from the strip.

12. A method of reducing a tread band of a vehicle tyre as claimed in Claim 11 , in which a perimeter of material is retained about the band to prevent reinforcing material constrained within the material matrix from releasing therefrom and fouling machinery.

13. An apparatus for reducing a vehicle tyre, the vehicle tyre having a tread portion supporting tread lugs or a tread pattern and sidewall portions connecting the tread portion to rim-engagable beads, to useable constituent parts using high- pressure water jets, the apparatus comprising:

programmable control means for positioning the water jet means;

water jet means for cutting the sidewalls from the tread portion of the tyre;

means for conveying the strip into a material removal station to remove rubber ^■ from the treat portion thereof.

14. An apparatus for reducing a vehicle tyre as claimed in Claim 13, in which the apparatus comprises means for separating rubber and fabric from effluent water generated during the reduction of vehicle tyres, wherein the apparatus comprises;

a separation tank to extract a majority of effluent water from a rubber crumb slurry presented thereto;

a press where further water is extracted from wet crumb from the separation tank;

15. An apparatus for reducing a vehicle tyre as claimed in Claim 13, in which the apparatus includes screening means for separating dry crumb according to size.

16. An apparatus for recovering tread lugs from a disused tyre, the apparatus comprising:

17. An apparatus for recovering tread lugs as claimed in Claim 16, in which the apparatus includes a means for collecting and conveying a slurry of tyre tread pieces and rubber crumb downstream to a crumb processing station.

18. A rim-engagable bead and a sidewall removal station, the station comprising:

a tyre rotation means for positioning a tyre adjacent a first fixed position pressurised cutting water jet and rotating said tyre so as to facilitate cutting of the rim-engagable bead portion from the sidewall portion of the tyre; a second pressurised cutting water jet positioned so as to facilitating cutting of the sidewall portion of the tyre from the tread portion thereof.

19. A rim-engagable bead and sidewall removal station as claimed in Claim 18, in which the station includes means for duplicating the bead and sidewall portion cutting on a second side of the tyre whereby an annular tread band is produced and is available for subsequent processing.

20. A rim-engagable bead and sidewall removal station as claimed in Claim 18 or Claim 19, in which both bead portions and both sidewall portions are removed sequentially but substantially simultaneously.

21. A rim-engagable bead and sidewall removal station as claimed in any one of Claims 18 to 20, in which the second pressurised cutting jet is angularly offset and radially disposed from the first bead cutting jet.

22. A tread band reducing station, the station comprising:

23. A tread band station as claimed in Claim 22, in which a perimeter of material is retained about the band to prevent reinforcing material constrained within the material matrix from releasing therefrom and fouling machinery.

24. A method of reducing a vehicle tyre substantially as herein described with reference to the accompanying drawings.

25. A method of recovering tread lugs substantially as herein described with reference to the accompanying drawings.

26. A method of removing a rim-engagable bead and a sidewall portion of a vehicle tyre substantially as herein described with reference to the accompanying drawings.

27. A method of reducing a tread band of a vehicle tyre substantially as herein described with reference to the accompanying drawings.

28. An apparatus for reducing a vehicle tyre substantially as herein described with reference to and as shown in the accompanying drawings.

29. An apparatus for recovering tread lugs substantially as herein described with reference to and as shown in the accompanying drawings.

30. A rim-engagable bead and sidewall removal station substantially as herein described with reference to and as shown in Figure 1 of the accompanying drawings.

31. A tread band reducing station substantially as herein described with reference to and as shown in Figure 1 of the accompanying drawings.