WO2004069499A1

WO2004069499A1 - Apparatus for and process of recycling tyres

Info

Publication number: WO2004069499A1
Application number: PCT/GB2004/000399
Authority: WO
Inventors: Robert Hotchkiss; Paul Glenn Mathers
Original assignee: Vhe Equipment Services Ltd.
Priority date: 2003-02-03
Filing date: 2004-01-30
Publication date: 2004-08-19
Also published as: GB2397783A; GB0302422D0; GB2397783B

Abstract

An apparatus for recycling tyres, the apparatus comprising a pair of opposed rotatable members between which a tyre to be recycled may be disposed, the rotatable members being adapted to engage the opposed sidewalls of a tyre, a drive device for rotating at least one of the rotatable members, a pressing device connected to at least one of the members for urging the members together thereby, in use, to compress a tyre therebetween, and at least one cutting device located and adapted to cut the outer circumferential surface of a tyre rotated by the members.

Description

APPARATUS FOR AND PROCESS OF RECYCLING TYRES

The present invention relates to an apparatus for and process of recycling tyres. In particular, the present invention relates to such an apparatus and process for recycling large tyres, typically over 1400 mm external diameter, which currently cannot be recycled using commercially acceptable processes. However, the invention may also be applied to the recycling of other tyres, such as automotive tyres, and tyres for fork lift trucks.

Very large numbers of worn automotive tyres are generated annually all over the world. These automotive tyres consist not only of smaller tyres for automobiles, but also larger tyres for trucks, agricultural machinery such as tractors, civil engineering machinery such as earthmovers, and other industrial machinery. Although some worn tyres can be re- treaded to be used again, the vast majority of tyres are simply required to be disposed of. There is a need to reduce the environmental impact of such waste tyres.

According to recent directives enacted by the European Union, any automotive tyre up to 1400 mm in external diameter must be recycled. The recycling process involves breaking up the tyre into its constituent components of, primarily, rubber and steel, separating them and reusing them in one form or another. There are a number of known technical and commercial uses for recycled tyre rubber. A wide variety of techniques are known in the art for recycling smaller tyres, using mechanical, thermal and chemical processes. However, to the applicants' knowledge is currently no known commercially employed method of recycling tyres over 1400 mm diameter, in particular earth mover tyres. Accordingly, such tyres are required to be sent to a landfill site for dumping in the ground. This obviously is undesirable from an environmental standpoint.

It is likely that in the future there will be an urgent need for tyre recycling apparatus and processes capable effectively of recycling larger tyres, because this is likely to be legislated for in the future.

Furthermore, with increasing legislative requirements for the recycling of tyres, there is a need for tyre recycling apparatus and methods which enable tyres to be recycled in a cost effective manner, so that recycling is commercially viable. Typically, known tyre recycling facilities not only require a very high capital cost for their construction, but also require a high running cost, typically with regard to the energy consumption needed to recycle the tyres. There is also a need in the art for tyre recycling apparatus and methods which can be achieved at reduced capital costs, and reduced running costs, compared to known processes.

A number of other apparatus and processes have been disclosed in the prior art for the recycling of tyres.

IT-A-01245992 discloses an apparatus and process for recycling tyres in which a tyre to be recycled is fed in a horizontal direction between a pair of rows of vertically oriented rollers which urge the leading edge of the tyre against a rotating cutter. Pieces of the tyre thereby formed fall onto a conveyor belt and are separated using a separating system. The rollers progressively squeeze the tyre inwardly in an axial direction, with respect to the axis of the tyre, as the tyre is fed towards the cutter. The cutter comprises three rotatable circular cutter elements, each having a respective grinding characteristic, mounted in series on a common shaft, with the shaft being translationally movable along its axis. In this way, a selected one of the cutter elements can engage the tyre.

The apparatus disclosed in IT-A-01245992 suffers from the disadvantage that it is not suitable for recycling larger tyres, for example having a diameter of greater than 1400 mm. Furthermore, the capital cost and operating cost of the apparatus would be quite high. In addition, although a separating system is provided to separate various fractions of the products produced from the tyre, there is still a need for a tyre recycling apparatus and process which can provide a customised rubber product, preferably at low capital and running cost.

GB-A-2344060 discloses a tyre granulator for granulating rubber in a recycling process, the granulator including a granulation chamber, housing a rotor, removably attached to stud shafts. The rotor has a plurality of flying blades distributed circumferentially around, and longitudinally along, the rotor. The rotor is driven by a hydraulic drive unit. This tyre granulator is not only not suitable for granulating larger tyres, typically greater than 1400 mm diameter, but also requires a high capital cost and high running costs.

WO-A-97/26122 discloses a process for the mechanical breaking up of used tyre casings and equipment therefor in which a tyre is fixed, inflated and rotated on a gear driven by a motor. Profile round broaches driven by respective motors are provided for cutting of the worn out tyre protector within 0.5 to 0.6 tyre revolutions are provided on respective feeding tables which are respectively moved by respective gears in a radial direction. Subsequent apparatus are provided for simultaneous cutting of the reinforced parts of the tyre and its break up into five ring shaped elements, cutting along the diameter of the tyres and final breaking up of the obtained semi-ring parts and their separation into rubber and metal shavings. The apparatus disclosed in this specification is not suitable for recycling large tyres typically over 1400 mm diameter and has a high capital cost.

GB-A-2339708 discloses a tyre recycling apparatus incorporating water jets for projecting water at high pressure onto the surface of the tyre to fragment the tyre into tyre fragments of different materials.

GB-A-2347365 discloses a vehicle tyre recycling process in which the tyre is exposed to a rapid cooling agent, such as liquid nitrogen, to render the tyre brittle, the tyre is then crushed or impacted to break it into a granule/powder form, and then the residue is exposed to a magnetic field in order to separate steel granules from rubber granules.

EP-A-0690091 and EP-A-0748837 disclose processes for recycling used elastomeric materials which comprises masticating elastomeric materials at temperatures below 50°C with a chemical mixture. WO-A-92/15438 discloses a method of recycling rubber and other constituents from used tyres having a reinforced tread pattern which comprises removing rubber from the tread portion down to substantially the reinforcement therein by using ultra high-pressure fluid jets. WO-A-99/08849 discloses an apparatus for recycling of old rubber tyres through oxygen-free pyrolysis in a connected continuously operating system. WO-A-00/069610 discloses a flow line for the complex recycling of tyres using a hydraulic-jet tyre-processing device and a device for the electro-thermal separation of the metallic cord from the rubber. WO-A-01/03473 discloses apparatus and processes for degrading tyres using microwave radiation. WO-A-01/17733 discloses a method for cutting up tyres with a view to recycling which consists in cutting the tread, so as to separate it from the two sidewalls, using a high pressure water jet.

US- A-2001/0047585 discloses a method of and installation for treating and recycling tyres in which bead cores present in the tyre rims are removed and thereafter the tyres are gradually crashed along their circumference.

DE-A-3232061 discloses a tyre recycling process in which wire inserts are separated from the waste rubber and then the waste rubber is comminuted by being fed between a roller and a toothed or corrugated pressure plate. DE-A-3313470 discloses a process for recycling used tyre rubber in the liquid phase. DE-A-3911082 discloses the electro thermal treatment of scrap tyres for recycling so that the metallic inserts are intensely heated and thereby break down into small particle or lose their hardness and strength by annealing. DE-A-4409064 discloses the recycling of used tyres in which the headings are cut clear and then stamped into shaped sections. CH-A-684253 discloses the recycling of tyres for industrial and transport vehicles in which markers indicating what thickness of material has been removed in a possible later rebuilding are inserted into the tyres and the sidewalls and tread and/or beads are reinforced. IT-A-1242334 discloses tyre recycling in which the tyres are crushed by feeding a crusher directly with tyres, and tyre fragments therefrom are fed to a grinding zone and thereafter to a refining zone for separating the material.

WO-A-95/07146, FR-A-2764227, JP-A-7186142 and RU-C-2044649 also discloses various apparatus and methods for recyling tyres.

These known apparatus and processes suffer from the problem that they are not suitable for the recycling of very large tyres typically over 1400 mm external diameter, or they require a high capital and/or running costs.

These known apparatus and processes also suffer from the problem that they are not readily capable of producing commercially a product of recycled rubber material which can be certified or customised in respect of the shape, dimension, morphology and/or particle distribution of the rubber pellets or particles produced by the recycling process. These known processes tend to provide rubber pellets of undefined particle distribution, or alternatively require additional process steps to separate the rubber particles produced into different sizes, etc.

The present invention aims to provide an apparatus and process for recycling tyres which not only is capable of recycling large tyres, typically having an external diameter greater than 1400 mm, but also requires only a low capital cost and also a low running cost as compared to some known processes. The present invention also aims to provide an apparatus and process having technical and commercial advantages for recycling smaller tyres, such as automobile tyres, as compared to known processes. The present invention also aims to provide an apparatus and process for recycling tyres which is capable of producing a recycled rubber product of defined particle distribution.

Accordingly, the present invention provides an apparatus for recycling tyres, the apparatus comprising a pair of opposed rotatable members between which a tyre to be recycled may be disposed, the rotatable members being adapted to engage the opposed sidewalls of a tyre, a drive device for rotating at least one of the rotatable members, a pressing device connected to at least one of the members for urging the members together thereby, in use, to compress a tyre therebetween, and at least one cutting device located and adapted to cut the outer circumferential surface of a tyre rotated by the members.

The present invention further provides a process of recycling tyres, the method comprising the steps of: (a) disposing a tyre to be recycled between a pair of opposed rotatable members so that the rotatable members engage the opposed sidewalls of the tyre; (b) rotating at least one of the rotatable members by a drive device therefor thereby to rotate the tyre about the rotational axis of the tyre; (c) cutting the outer circumferential surface of the rotating tyre by at least one cutting device; and (d) urging the members together, so as to compress the tyre therebetween and progressively to deform the outer circumferential surface of the rotating tyre radially outwardly as material of the tyre is progressively cut away therefrom, by means of a pressing device connected to at least one of the members. Embodiments of the present invention will be described, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a schematic side view of an apparatus for recycling tyres in accordance with a first embodiment of the present invention;

Figure 2 is a schematic part-sectional end view of the apparatus of Figure 1;

Figure 3 is a schematic part-sectional view through a first modified construction of one of the pair of flange plates of the apparatus of Figure 1;

Figure 4 is a schematic part-sectional view through a second modified construction of one of the pair of rotatable pressing members of the apparatus of Figure 1;

Figure 5 is a perspective side view of a first alternative cutting element for use in the apparatus of Figure 1; and

Figure 6 is a side view of a second alternative cutting element for use in the apparatus of

Figure 1.

Referring to Figures 1 and 2, an apparatus, designated generally as 2, for recycling tyres in accordance with an embodiment of the present invention comprises a base 4, for standing on the floor, and a frame 6 comprising a pair of upright frame members 8,10 which are spaced apart to define therebetween a space 12 for receiving a tyre 14 to be recycled. At the upper end 16 of a first frame member 8 is mounted a pressure ram assembly 18 which includes a ram member 20 rotatably mounted in bearings 22,24 for rotational movement of the ram member 20 about a horizontal axis 25. The ram member 20 is connected to a pressure-drive device (not shown), which may be pneumatically or hydraulically operated, which is adapted selectively to move the ram member 20 translationally along the horizontal axis 25 in the direction of the arrows A- A' illustrated in Figure 2.

At an inward end 26 of the ram member 20 is mounted a first flange plate 28, which is located within the space 12. A second parallel opposite flange plate 30 is also mounted in the space 12 on an inward end 32 of a drive shaft 34 of a rotational drive device 36 which is mounted on the upper end 38 of the second frame member 10. The drive shaft 34 has an axis of rotation coincident with the horizontal axis 25. The drive device 36 in this embodiment comprises a fixed pulley member 40 affixed to the drive shaft 34. The pulley member 40 is driven by a drive belt (not shown) coupled to a drive motor (not shown) whereby the drive shaft 34 can be rotatably driven in the direction of the arrow B in Figure 2.

The first and second parallel flange plates 28,30, which constitute a particular preferred form of rotatable pressing members, are shaped, configured and dimensioned so as to be capable of receiving therebetween a tyre 14 to be recycled. In particular, the flange plates 28,30 are circular, and have an outer diameter selected to be slightly larger than the internal diameter of a tyre 14 to be recycled using the recycling apparatus. Accordingly, as shown in Figure 2, a tyre 14 to be recycled can be mounted between the flange plates 28,30 in such a way that a peripheral edge 42,44 of the inwardly facing surface 46,48 of the flange plate 28,30 bears against an axially outer surface 50,52 of a respective bead 54,56 of the tyre 14.

As shown in Figure 3, in a modification according to a further embodiment of the invention, the inwardly directed surface 46,48 of each flange plate 28,30 has mounted thereon an annular tyre rim locator 58 for engaging and holding the tyre bead 54,56. Each rim locator 58 defines an annular recess 60 into which the tyre bead 54,56 may be received and held securely so as to prevent inadvertent radial movement of the tyre bead 54,56. If desired, the rim locator 58 may comprise a plurality of spaced chordal sections which can be radially moved so as to be able to engage the tyre beads of a variety of differently sized tyres. Alternatively, a plurality of pairs of flange plates, with or without the provision of rim locators, may be provided, for mounting differently sized tyres, with the flanges plates being removably attached to the pressure ram 20 and the drive shaft 34.

In a modification according to a yet further embodiment of the invention, as shown in Figure 4, the rotatable pressing members comprise, instead of flange plates, opposed conical heads 62, 64. One conical head 62 is mounted on the ram 20 and the other conical head 64 is mounted on the drive shaft 34. Each conical head 62, 64 has an inwardly directed conical (or frustoconical as shown in phantom) surface 66, 68, coaxial with the ram 20 and the drive shaft 34. Therefore the two conical surfaces 66, 68 oppose each other as shown in Figure 4, to define opposed mounting surfaces of continuously and progressively increasing radius. The conical surfaces 66, 68 are coaxial with a rotational axis of the drive device, and the opposed conical surfaces 66, 68 decrease in radius in a direction towards the other conical surface 66, 68. The inwardly directed conical surfaces 66,68 engage and hold the respective tyre beads 63, 65 of a tyre 67, with the conical surfaces 66,68 partly extending into the central recess 69 of the tyre 67. The tyre beads 63, 65 can be squeezed between the conical surfaces 66,68 so that they are held securely so as to prevent inadvertent radial movement of the tyre beads 63, 65. The provision of conical surfaces 66,68 readily enables secure mounting of differently sized tyres, in particular having different diameter tyre beads, without requiring removal of flanges plates as in the first embodiment. Also, the conical surfaces 66,68 are particularly suitable for mounting small radial dimension tyres, such as tyres for fork-lift tracks. In practice, the conical surfaces 66,68 can accommodate a continuous range of different internal tyre bead diameters, with contact between the bead and the cone being located a few millimetres from the apex of the cone (or from the small diameter end of a frustoconical head) up to the large diameter end of the head.

As shown in Figure 1, a cutting head 70 is mounted at the upper end 72 of an upright support member 74 mounted on the base 4. The cutting head 70 is located at substantially the same height but laterally spaced from the horizontal axis 25 about which the tyre is in use rotated so as to be engageable with the outer rim of the tyre 14. The cutting head 70 comprises a rotatable drum 76 mounted on an axle 78 which is fixed to a cutter base 80 which is adapted to be movable translationally over a table 82 affixed to the support member 74. The cutter base 80 is movable in two orthogonal directions, first a horizontal direction substantially radial with respect to the tyre 14 and, second a horizontal direction which is parallel to the rotational axis of the tyre 14. The movement in the radial direction is shown by the arrows C-C in Figure 1.

The cutting head 70 comprises an endless cutting belt 84 which is mounted about the drum 76 and about a remote rotatable drive shaft 86, the drive shaft 86 being connected to a drive motor (not shown). The cutter belt 84 is of generally known construction and comprises a plurality of metallic cutting elements, of typical roughness from 20 to 80 grit size, disposed randomly on and extending outwardly from the surface of the belt 84.

In accordance with preferred aspects of the invention, the cutter belt and optionally the associated cutter drum are interchangeable, so that different cutting heads can be employed, each having a different cutting surface, which is selected dependent on the type of material being cut.

Alternatively, the cutting head 70 may comprise a cutting wheel, such as that illustrated in Figure 5, which is known in the art as a "hog wheel" cutting wheel, and comprises a plurality of metallic cutting elements 88 of predetermined size located on the outer cylindrical peripheral surface 90 of the wheel 92. These cutting elements 88 have a size and distribution substantially similar to that of a 20 to 80 mesh cutting belt.

In a yet further alternative structure for the cutting head 70, as shown in Figure 6, the cutting head 70 may comprise a milling cutter 94, having a plurality of substantially radially extending milling teeth 96, each separated by a selected milling pitch length x shown in Figure 6, for example, around 30 mm. The milling cutter 94 may have from 30 to 200 circumferentially separated teeth with the cutter diameter typically ranging from 100 to 450mm. When a cutting wheel or milling cutter is employed, the drive motor drives the cutting element by a drive belt.

The operation of the apparatus will now be described.

A tyre 14 to be recycled is located between the flange plates 28,30 in the configuration illustrated in Figures 1 and 2, and optionally on the rim locators 58 when present, so that the axis of the tyre 14 is coincident with the horizontal axis 25 of the pressure ram 20 and of the drive shaft 34. The pressure ram assembly 18 is then operated so as to move the pressure ram 20, and the first flange plate 28 mounted thereon, inwardly towards the second flange plate 30, thereby to squeeze the tyre beads 54,56 of the tyre 14 between the flange plates 28,30 and secure the tyre 14 in the apparatus.

The drive shaft 34 is then rotated by the drive device 36 in the direction of the arrow B so as to rotate the tyre 14 in the direction of the arrow D shown in Figure 1. Typically, the tyre is rotated at an angular velocity of 0.5 to 6 rpm, most typically about 2 rpm. A selected cutting head 70, mounted on the cutter base 80, is rotated by the drive motor and is translationally moved across the table 82 towards the rotating tyre 14 so that the outer cutting surface of the cutting head 70 engages the outer cylindrical tread surface of the tyre 14. The cutting head 70 is rotated about arrow E in Figure 1 in the same rotational sense as that of the tyre 14. The cutter head is also moved translationally in a direction parallel to the axis of the rotating tyre 14. In this way, a layer of rubber is cut away from the tyre 14 in particulate form. The rubber particles cut away from the tyre 14 fall by gravity and may be collected.

As progressively more rubber is cut from the outer circumferential surface of the tyre 14, the tyre 14 weakens structurally and the pressure from the pressure ram 20 is progressively increased so as to urge flange plate 28 progressively nearer to flange plate 30. In this way, the tyre 14 is progressively deformed so that the tread of the tyre, at the outer circumferential surface, is progressively deformed radially outwardly towards the cutting head 70, by compressing together the opposed beads 54,56 of the tyre 14.

After sufficient rubber has been cut away from the external circumferential periphery of the tyre 14, the reinforcing steel wires of the tyre 14 are exposed, which can be determined visually by a user, and at this point the cutting head 70 can be interchanged so as to employ an abrasive grinding belt selected so as to be suitable for grinding down the metal in the tyre 14 until the radially outer flanges of the beads 54,56 of the tyre 14 are reached. Upon reaching the flanges of the beads 54,56, the pressure urging together the two flange plates 28,30 is released and the remaining two tyre beads 54,56 are removed and subject to a steel recycling process. Thereafter, the process is repeated on a further tyre 14 to be recycled.

The cutter head 70, whether a cutter belt, a cutting wheel or a milling cutter, is selected not only with respect to the nature of the rubber being cut away from the tyre, but also so that a particular size, shape and distribution of rubber particles is generated as a result of the cutting action. The size and shape of the particles is also controlled by the speed of rotation of the cutting head 70. When a cutting belt is present, typically the translational speed of the surface of the cutter belt is from 25 to 60 metres per second, most typically around 45 metres per second. The provision of interchangeable cutting heads in accordance with the apparatus and method of the invention enables the size, morphology and distribution of the rubber pellets produced to be customised by using one or a number of selected cutting heads. In this way, the apparatus and method of the invention can provide a specific end product for an end user of the recycled rubber particles. This provides a specific advantage over known recycling processes, which tend to provide an undefined distribution of rabber particles of varying size, shape and morphology.

In accordance with the apparatus and method of the present invention, as a result of rotating the tyre and providing a cutting. head which progressively cuts away the outer circumferential peripheral tread surface of the tyre, not only does the apparatus . of the invention have low capital costs compared to known apparatus, but also the apparatus has a low run-ning cost because the electrical energy required to cut away not only the rubber but also the steel from the tyre so as to leave only the beads, is much lower than known processes. For example, it is believed by the present inventor that the energy requirement to recycle a large tyre, for example an earthmover tyre, having an external diameter of greater than 1400 mm in accordance with the invention is typically less than 10 times (an order of magnitude) less than that required by a corresponding process using a cascade of grinders for grinding a tyre into progressively small particle sizes. The significant cost advantages render the apparatus and process of the invention commercially acceptable for processing large tyres. However, the apparatus and process of the present invention also provides technical and commercial advantages for recycling smaller tyres, such as automobile tyres, as compared to known processes.

Furthermore, by rotating the tyre itself against a rotating cutting element, and with the provision of a plurality of different cutting elements, there is provided a process which can effectively recycle large tyres such as earthmover tyres. This is a significant technical advantage and obviates the requirement for large tyres to be dumped into landfill sites, as at present.

In addition, by providing that the tyre is progressively deformed by the flange plates as the rubber is progressively removed from the tyre, this provides a relatively straightforward mechanical construction which nevertheless ensures reliable removal of the rubber from the tyre.

Yet further, the provision of a plurality of interchangeable cutting heads, each of defined cutting characteristics, enables the recycled rubber material to be customised in respect of the shape, dimension, morphology and particulate distribution of the rubber pellets or particles produced by the cutting process. This provides a significant technical and commercial advantage over known processes which tend to provide rabber pellets of undefined particle distribution, or alternatively require additional process steps to separate the rabber particles produced into different sizes, shapes, etc. The commercial value of the recycled rabber product is greatly enhanced by being able to define the distribution of the recycled rabber particles, and if desired to customise that distribution to the needs of the user. If desired, a particle size grader, for example a sieve, can be additionally employed for sieve analysis of the rabber particles. Inn this way, the customer or user of the particles is able to determine or confirm their size and distribution. In addition, the number of applications for the use of recyclable particles is increased by the ability to customise the rubber particulate distribution.

The process and apparatus of the invention operate so as hold the bead and to remove all of the rubber and steel from the tyre so that the beads are left which can then be used for further recycling later. Therefore the structure of the bead is employed to support an rotate the tyre in the operation of the process of the invention and the apparatus is constructed so that the bead is held, and compressed, while the tyre is rotating so that the tread portion can be cut by the cutting device. However, conventional tyre debeaders tear out the treads before the tyres are granulated and the beads are discarded. The present invention may make the commercial use of tyre debeaders redundant.

Claims

CLAIMS:

1. An apparatus for recycling tyres, the apparatus comprising a pair of opposed rotatable members between which a tyre to be recycled may be disposed, the rotatable members being adapted to engage the opposed sidewalls of a tyre, a drive device for rotating at least one of the rotatable members, a pressing device connected to at least one of the members for urging the members together thereby, in use, to compress a tyre therebetween, and at least one cutting device located and adapted to cut the outer circumferential surface of a tyre rotated by the members.

2. An apparatus according to claim 1 wherein the rotatable members are circular plate members coaxial with a rotational axis of the drive device.

3. An apparatus according to claim 2 further comprising an annular rim locator disposed on an inwardly directed surface of each plate member for engaging and holding a bead of a tyre.

4. An apparatus according to claim 3 wherein the rim locator defines an annular recess into which the tyre bead is, in use, received.

5. An apparatus according to claim 1 wherein the rotatable members are opposed heads each having a conical surface coaxial with a rotational axis of the drive device, the opposed conical surfaces decreasing in radius in a direction towards the other conical surface.

6. An apparatus according to claim 5 ftirther wherein the heads are conical.

7. An apparatus according to claim 5 wherein the heads are frustoconical.

8. An apparatus according to any foregoing claim wherein the pressing device comprises a pressure ram assembly including a ram member which is rotatably mounted for rotatable movement about a rotational axis of the drive device and a pressure-drive device which is adapted selectively to move the ram member translationally along the rotational axis.

9. An apparatus according to claim 8 wherein the pressure-drive device is pneumatically or hydraulically operated.

10. An apparatus according to any foregoing claim wherein the at least one cutting device is rotatable and further comprising a drive means for rotating the at least one cutting device, the drive means being adapted to rotate the at least one cutting device in the same rotational sense as the drive device for the at least one rotatable member.

11. An apparatus according to any foregoing claim wherein the cutting device comprises a rotatable drum mounted about an axle, a rotatable drive shaft spaced from the drum, and an endless cutting belt mounted about the dram and about the rotatable drive shaft, the cutter belt having a plurality of metallic cutting elements disposed randomly on and extending outwardly from an outer surface of the belt.

12. An apparatus according to claim 11 wherein the cutting belt has a roughness of from 20 to 80 grit size.

13. An apparatus according to any one of claims 1 to 10 wherein the cutting device comprises a rotatable cutting wheel having an a plurality of metallic cutting elements of predetermined size and pitch located on the outer cylindrical peripheral surface of the wheel.

14. An apparatus according to any one of claims 1 to 10 wherein the cutting device comprises a rotatable milling cutter having a plurality of substantially radially extending milling teeth of predetermined size and pitch.

15. An apparatus according to claim 14 wherein the milling cutter has from 30 to 200 cixcumferentially separated teeth with the cutter diameter ranging from 100 to 450mm.

16. An apparatus according to any foregoing claim further comprising a moving device for the at least one cutting device, the moving device being adapted to move the or each cutting device translationally both radially and axially with respect to the rotational axis of the rotatable members.

17. An apparatus according to any foregoing claim comprising a plurality of interchangeable cutting devices, each removably attachable to a common cutter support, each cutting device being adapted to cut a different particle size from the surface of the tyre.

18. A process of recycling tyres, the method comprising the steps of:

(a) disposing a tyre to be recycled between a pair of opposed rotatable members so that the rotatable members engage the opposed sidewalls of the tyre;

(b) rotating at least one of the rotatable members by a drive device therefor thereby to rotate the tyre about the rotational axis of the tyre;

(c) cutting the outer circumferential surface of the rotating tyre by at least one cutting device; and

(d) urging the members together, so as to compress the tyre therebetween and progressively to deform the outer circumferential surface of the rotating tyre radially outwardly as material of the tyre is progressively cut away therefrom, by means of a pressing device connected to at least one of the members.

19. A process according to claim 18 wherein the rotatable members are circular plate members coaxial with a rotational axis of the drive device.

20. A process according to claim 19 further comprising the step of locating a bead of the tyre in an annular rim locator disposed on an inwardly directed surface of each plate member so as to engage and hold the bead.

21. A process according to claim 20 wherein the rim locator defines an annular recess into which the tyre bead is received.

22. A process according to claim 18 wherein the rotatable members are opposed heads each having a conical surface coaxial with a rotational axis of the drive device, the opposed conical surfaces decreasing in radius in a direction towards the other conical surface.

23. A process according to any one of claims 18 to 22 wherein the pressing device comprises a pressure ram assembly including a ram member which is rotatably mounted for rotatable movement about a rotational axis of the drive device and a pressure-drive device which is adapted selectively to move the ram member translationally along the rotational axis in step (d).

24. A process according to claim 23 wherein the pressure-drive device is pneumatically or hydraulically operated.

25. A process according to any one of claims 18 to 24 wherein the at least one cutting device is rotatable by a drive means therefor, and further comprising, during the cutting step (c), rotating the at least one cutting device in the same rotational sense as the drive device for the at least one rotatable member.

26. A process according to any one of claims 18 to 25 wherein the cutting device comprises a rotatable dram mounted about an axle, a rotatable drive shaft spaced from the drum, and an endless cutting belt mounted about the dram and about the rotatable drive shaft, the cutter belt having a plurality of metallic cutting elements disposed randomly on and extending outwardly from an outer surface of the belt, and in cutting step (c) the tyre is cut into particles having at least a size determined by at least the size of the metallic cutting elements.

27. A process according to claim 26 wherein the cutting belt has a roughness of from 20 to 80 grit size.

28. A process according to claim 26 or claim 27 wherein the cutting belt has a velocity of from 25 to 60 metres per second during the cutting step.

29. A process according to any one of claims 18 to 25 wherein the cutting device comprises a rotatable cutting wheel having an a plurahty of metallic cutting elements of predetermined size and pitch located on the outer cylindrical peripheral surface of the wheel, and in cutting step (c) the tyre is cut into particles having at least a size determined by at least the size and pitch of the metallic cutting elements.

30. A process according to any one of claims 18 to 25 wherein the cutting device comprises a rotatable milling cutter having a plurality of substantially radially extending milling teeth of predetermined size and pitch, and in cutting step (c) the tyre is cut into particles having at least a size determined by at least the size and pitch of the milling teeth.

31. A process according to claim 30 wherein the milling cutter has from 30 to 200 circumferentially separated teeth with the cutter diameter ranging from 100 to 450mm.

32. A process according to any one of claims 18 to 31 further comprising the step, during the cutting step (c), of moving the or each cutting device translationally both radially and axially with respect to the rotational axis of the rotatable members.

33. A process according to any one of claims 18 to 32 wherein in the cutting step (c) the tyre surface is cut sequentially by a plurality of interchangeable cutting devices, each removably attachable to a common cutter support, each cutting device being adapted to cut a different particle size from the surface of the tyre.

34. A process according to any one of claims 18 to 33 wherein the tyre is rotated at an angular velocity of 0.5 to 6 rpm.

35. An apparatus for recycling tyres substantially as hereinbefore described with reference to the accompanying drawings.

36. A process for recycling tyres substantially as hereinbefore described with reference to the accompanying drawings.