Recycling of Rubber
Practical Action
Material re-use
The next step in our hierarchy involves the material being broken down and reused for the
production of a new product. As mentioned earlier, in developing countries this hand
reprocessing of rubber products to produce consumer goods is well established and the
variety of products being made from reclaimed tyres and tubes is astonishing. The rubber
used in tyres is a relatively easy material to reform by hand. It behaves in a similar manner to
leather and has in fact replaced leather for a number of applications. The tools required for
making products directly from tyre rubber are not expensive and are few in number. Shears,
knives, tongs, hammers, etc., all common tools found in the recyclers’ workshop, along with a
wide range of improvised tools for specialised applications. Shoes, sandals, buckets, motor
vehicle parts, doormats, water containers, pots, plant pots dustbins and bicycles pedals are
among the products manufactured.
Another way in which physical reuse can be achieved is by reducing the tyre to a granular
form and then reprocessing. This can be a costly process and there has to be a manufacturer
willing to purchase the granules. Crumb rubber from the retreading process can be used in
this way, as it is a good quality granulated rubber. The reprocessing techniques used are
similar to those described in earlier chapters. Granulate tends to be used for low-grade
products such as automobile floor mats, shoe soles, rubber wheels for carts and barrows, etc.,
and can be added to asphalt for road construction, where it improved the properties of this
material.
Figure 4: Garbage containers made
from Truck tyres. Manila, The
Philippines.
Photo: CAPS - WASTE
Chemical and thermal recovery
This type of recovery is not only lower in the waste management hierarchy, but is also a higher
technology requiring sophisticated equipment. The applicability of such technologies for
small-scale applications in developing countries is very limited. We will therefore look only
very briefly at a couple of processes. Chemical recovery is the process of heating waste
rubber reclaim, treating it with chemicals and then processing the rubber mechanically.
Acid reclamation – uses hot sulphuric acid to destroy the fabric incorporated in the tyre
and heat treatment to render the scrap rubber sufficiently plastic to allow its use as a
filler with batches of crude rubber.
Alkali recovery - Reclaimed rubber, treated by heating with alkali for 12 to 30 hours, can
be used as an adulterant of crude rubber to lower the price of the finished article. The
amounts of reclaimed rubber that are used depend on the quality of the article to be
manufactured.
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