WO2003057442A1

WO2003057442A1 - The disintegration of rubber tyres using ultra high pressure fluid jets

Info

Publication number: WO2003057442A1
Application number: PCT/GB2003/000037
Authority: WO
Inventors: Donald Blair
Original assignee: TIRELESS TECHNOLOGY Ltd
Current assignee: TIRELESS TECHNOLOGY Ltd
Priority date: 2002-01-08
Filing date: 2003-01-08
Publication date: 2003-07-17
Anticipated expiration: 2004-07-08
Also published as: GB0200368D0; AU2003201036A1

Abstract

A method for reclaiming rubber and other constituents form waste tyres, including those having metal reinforced sections, comprising the removal of the rubber from the various sections of the tyre(a), including the butyl rubber inner liner, the tread and the sidewall, to yield rubber crumb of various and controlled size, depending on the processing variables used, leaving the metal reinforcement, by the use of ultra high pressure fluid jets(d), in particular water, and subsequently reclaiming the rubber, textile fibre and the metal reinforcement. This is the best illustrated in Figure 1 which shows a tyre, held under pressure rollers(b,c) and subjected to ultra high pressure fluid from rotating jets which are effective in reducing the rubber to rubber crumb and releasing any metal or textile present.

Description

THE DISINTEGRATION OF RUBBER

TYRES USING ULTRA HIGH

PRESSURE FLUID JETS

This invention relates to a method and apparatus for reclaiming rubber and other constituents from waste tyres.

The method and apparatus may be used to solve the major problem of waste tyres worldwide. For example in 1991 the United States government proposed legislation relating to the increasing threat to the environment from huge stockpiles of waste tyres. The 'Tire Recycling and Recovery Act', if enforced, may require that existing stockpiles of three billion waste tyres be removed by the year 2005, together with the annual waste tyre generation of 240 million. In Europe, 240 million waste tyres are also generated annually, 25 million in the UK alone.

Used and waste tyres have traditionally been dumped, disposed of in landfills, or, more recently, incinerated. Other methods have been tried which are also environmentally unsound, resulting in significant environmental problems. Dumps can catch fire, releasing toxic fumes and water escaping from these dumps may contain toxic elements. Tyres can also float to the surface of landfill and cause enclosure problems.

Because of the above mentioned problems, arid in the light of recent and impending legislation, there is a need for an alternative method. According to the present invention, the alternative method detailed relates also to alternate uses for the products from waste tyres. The method will allow total recycling of the components and their re-use.

A particular application for the fine rubber crumb which can be obtained from waste tyres using this invention is the incorporation of the crumb into new tyres.

Fine crumb of this type can also be used as a filler for plastics.

Rubber crumb can be used in applications such as road pavement, i.e., an addition to asphalt paving to impart enhanced properties to the surface.

Sports surfaces can utilise rubber crumb as a component and there are many further uses which have been inhibited from growth die to the lack of consistent and economically priced rubber crumb.

The recycling technique must be capable of recovering all materials present in the tyre; rubber, textile fibre, and metal. Furthermore, the recycling method must be able to separate these component materials in order to provide a marketable product.

Also, such a recycling method must not be associated with the environmental problems associated with previous attempts to recycle waste tyres.

The aim of the present invention is to provide an improved method and apparatus for reclaiming of rubber and other constituents from waste tyres.

The present invention gives a method of reclaiming the constituent materials of waste tyres by removing the rubber and at the same time reducing it to crumb by using ultra high pressure fluid jets.

The preferred form of the invention is for the coaxial bead wire to be removed after which the tyre undergoes sequential operations to separate the individual components and convert the tyre constituents to a size suitable for further recovery and use.

The tyre is first treated by cutting across its cross section and then holding the tyre flat beneath rollers by means of hydraulic or other pressures and then subjecting the tyre to a rotating and/or traversing ultra high pressure fluid jet in order to reduce the rubber to crumb.

For example, the tyre is fed between pressure rollers and subjected to action from single or multiple ultra high pressure jet heads operated in the pressure region of 1 ,500 to 4,000 bar. The action of the jet mills the rubber from the tyre.

In this process the tyre may be held vertically or horizontally.

The resultant crumb is then collected and recovered for further treatment which may be drying and sieving to achieve particular crumb sizes.

The rubber removed from the tread section may be used as granulated, crumbed or powdered rubber for any of the particular applications described above.

The size and quality of this rubber product may be altered by the pressure, configuration and location of the ultra high pressure fluid jets. For example, the nature of the products is determined by the actual fluid pressure used, between 1 ,500 and 4,000 bar, the number of jets used in each jet head, the orientation of the jets, preferably between 90 degrees and 35 degrees to the tyre, the rotational or traversing speed of the jets, the distance of the jets from the tyre and the speed at which the tyre is presented to and passes the jets.

At this stage the clean steel reinforcement previously contained within the tread section is collected by a rotating flapper wheel which can direct the steel fibres to a device which prepares it for subsequent processing, particularly as steel needles. In a possible next stage of the operation the residual tyre, after rubber is removed above and around any steel reinforcing fibres, is then continued along its path between rollers as the remainder of the tyre is subjected to ultra high pressure fluid, traversing or rotating jets reducing the remaining rubber to fine crumb which can be collected separately.

The use of ultra high pressure fluid jets, and in particular when these jets are water jets, is particularly advantageous to this method and invention. For example, viscoelastic materials such as rubber are difficult to cut by conventional cutting methods but are relatively easy to cut using ultra high pressure water.

There is only a negligible amount of heat generated by the cutting action which may otherwise cause the agglomeration of rubber particles. Further still, no metallic fines are produced by the stripping of the rubber from the metal reinforcement.

Furthermore, the granulated rubber crumb or fines are automatically washed during the cutting process and thus only require subsequent dewatering and drying, prior to any sieving or grading process and to packing.

Any textile particles present may first be removed by methods such as flotation, air separation or by agitation after drying, etc.

The crumb may be passed through rollers to remove excess water or vibrating dewatering screens can be used to remove more water before passing into a rotary kiln dryer. The water may be recovered and recycled after filtration.

Vibrating screens can also be used to separate the crumb into different particle sizes.

Water jets having an orifice size from 0.10 mm to p.25 mm diameter are used in the process, resulting in water jet velocities up to 1000 metres per second at fluid pressures ranging from 1 ,500 to 4,000 bar, the preferred range being normally of the order of 2,750 to 3,900 bar.

One form of the invention is that in which the waste tyre may be subjected to a single operation where ultra high pressure water jets are used to fragment all of the constituents to produce a pulp material which can then be sieved, graded and classified.

The metal components can then be removed by magnetic methods or by gravitation techniques.

The method described in this invention may be readily automated by known automation technology. It may also be subjected to building in a mobile form and incorporated on to a truck or trailer which may be taken to landfill sites for processing tyres. Such a mobile unit could be powered by a diesel generator.

The system described, using ultra high pressure water to reduce waste tyres to constituent components, could be enclosed using acoustic insulation, to reduce noise from the operation of the ultra high pressure fluid generating equipment at supersonic velocities. This will also serve to contain all the granules produced and enclosed the resulting spray.

This method for the recycling of waste tyres is environmentally friendly and eliminates any serious fire, health, safety or pollution concerns. The process produces no pollutant, residuals, odours, fumes or noxious emissions, toxic gases or vapours, dust residual fluids or excessive operational noise levels. It does not involve chemicals or the combustion of materials, heat is not generated and there are no waste products generated by the process.

The process described, therefore, is a method and apparatus for converting waste tyres to useful by-products such as granulated, crumbed or powdered rubber together with textile fibre and morphologically unchanged steel wire.

The process can vary the size of the rubber product and is able to operate on a wide variety and type and sizes of waste tyres. The method of this invention is not only cost effective in solving an existing problem but also generates an engineering material with a range of applications, not least that of incorporation into new tyres.

The invention will now be described in detail in relation to the method used. The following description is not to limit the generality of the description.

IN THE DRAWING

Figure 1 is a schematic side view of a tyre (A) split through its thickness, held between rollers (B) and carrier anvils (C).

Rotating or traversing jets (D) remove the rubber from above and between the steel reinforcement. This is then taken for collection and further treatment elsewhere.

The remaining rubber in the tyre is then removed by a further sequence of jets.

Referring to Figure 1. Waste tyres cut through their cross section, are fed between pressure rollers to the first treatment stage in which traversing and/or rotating ultra high pressure fluid jets remove the rubber above and between the steel reinforcement.

The steel reinforcement is then picked up by a rotating flapper wheel (E) which feeds the steel to a collecting device (F) from which it may be obtained in a form suitable for further treatment, for example, chopped to the size of steel needles for the reinforced concrete industry.

The steel bead wires can be treated separately by ultra high pressure fluid jets, to remove the rubber after which the steel is dried for further treatment. The tyre then moves, under the action of the rollers, to the second treatment stage (G) where the remaining rubber is reduced to crumb by rotating or traversing ultra high pressure water jets. The rubber crumb, as various sizes, can then be taken, by conveyor belts or by screw conveyors, to a treatment area where it is dried, sieved for further classifying, weighed, packaged and dispatched. Any textile fibre can be removed first by agitation or flotation. The metal fibres can also be dried and subjected to any further treatment before being weighed, packaged and dispatched.

The machine for carrying out these operations may be of the order of 4 to 5 metres in length by 1 to 2 metres wide. Such a compact unit could easily be adapted to work from a mobile unit.

Claims

THE CLAIMS DEFINING THE INVENTIONS ARE AS FOLLOWS

1. An apparatus in which the waste tyres are first cut through their cross section and then moved under the influence of pressure rollers, which may be operated hydraulically or by other means, and then subjected to a sequential movement through a number of treatment stages in which rubber is removed to leave only clean steel from the treat reinforcing wires and the circumferential steel bead wire.

2. A method of reclaiming rubber and other constituents from used tyres which have a reinforced tread after the tyre is cut through its cross section and moved laterally between rollers.

The method involves removing the rubber from the tread portion quickly and effectively, yielding a crumb of controlled size, and the steel reinforcement, by using ultra high pressure fluid jets, which may preferably be water, and subsequently converting the residual tyre components to form suitable for recovery, before being dried, sieved and packaged.

3. A method according to Claim 1 wherein the rubber is removed from the remaining tyre carcass, using rotating or traversing ultra high pressure water jets, each head containing a number of jets, after the tyre is split across its width and moved laterally between rollers.

4. A method, after treatment as described in Claim 2 by which residual steel reinforcing are collected, dried and packaged.

5. A method according to any one of the claims 1 to 4 wherein the residual components are subjected to a single operation where the ultra high pressure fluid jets are used to fragment all the constituents concurrently to produce a pulp from which the rubber and steel can be separated by flotation and classifying operations.

6. A method according to any one of the Claims 1 to 5 adapted to be provided in a mobile form.