Recycling of Rubber
Table 3: Principal rubber recycling processing paths (adapted from van Baarle)
Damaged tyres are, more often than not, repaired. Tubes can be patched and tyres can be
repaired by one of a number of methods. Regrooving is a practice carried out in many
developing countries where regulations are slacker and standards are lower (and speeds are
lower) than in the West. It is often carried out by hand and is labour intensive.
The use of retread tyres saves valuable energy and resources. A new tyre requires 23L of
crude oil equivalent for raw materials and 9L for process energy compared with 7L and 2L
respectively for retreading. Tyres of passenger vehicles can generally be retreaded only once
while truck and bus tyres can be retreaded up to six times. Retreading is a well established
and acceptable (in safety terms) practice. The process involves the removal of the remaining
tread (producing tyre crumb – see later) and the application and vulcanisation of a new tread
(the ‘camel back’) onto the remaining carcass. In Nairobi about 10,000 tyres a week are
received for retreading (Ahmed).
Secondary reuse of whole tyres is the next step in the waste management hierarchy. Tyres are
often put to use because of their shape, weight, form or volume. Some examples of
secondary use in industrialised countries include use for erosion control, as tree guards, in
artificial reefs, fences or as garden decoration. In developing countries wells can be lined
with old tyres, docks are often lined with old tyres which act as shock absorbers, and similarly
crash barriers can be constructed from old tyres. Old inner tubes also have many uses;
swimming aids and water containers being two simple examples.
Figure 3: Following the grooves is a Labour
Photo: Knud Sauer - WASTE