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2.2 Recycling

Eventually, all tyres become unsafe to use even though the majority of the

material used to make the tyre is still present. Retreading, or the addition of a new

tread to an old tyre, can be performed on heavy vehicle tyres several times over

before these tyres also become unsafe. Therefore, recycling is an integral part to tyre

waste management around the world. The recycling techniques described below are

several of the possible solutions for the recycling of waste tyres in Hong Kong.

2.2.1 Shredded Rubber

Most recycling processes require the tyres to be shredded before further

processing (Clark, Meardon, & Russell, 1993). Shredding allows for much more

efficient transportation of tyre waste, as it can reduce the volume of the tyres by about

75%. Tyre shredding also eliminates many of the problems associated with above

ground storage in stockpiles. The tyre shreds do not allow water to build up and

become breeding grounds for insects, and the volume reduction allows for much more

efficient use of land. Of course the problems with fire hazards still remain.

Shredding Equipment

Tyre shredding equipment is moderately expensive and consumes lots of

power. The tyre as a whole is first shredded to two-inch shreds. These shreds, about

the size of the palm of your hand, are not too useful by themselves other than the

volume reduction as they still contain the metal wires from the tyre (Lundin, personal

communication, November 28, 2006. See Appendix D). These shreds are put through

additional shredding equipment to reduce the size of the shreds to about one inch.

During this last shredding process the metal wires from the tyre are removed by

magnetic means. A rotating magnetic drum draws the metal wires out of the shreds

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