Thermal Conversion of Rubber Wastes and Used Tyres

6 Thermal Conversion of Rubber Wastes and Used Tyres 

In recent decades much interest has been generated in the reclamation of rubber wastes, mainly used tyres, by thermal decomposition. As tyres contain significant amounts of other components, in addition to rubber, the thermal conversion of tyres is a more complex process than the thermolysis of rubber alone. 

During the last 25 years a variety of processes have been developed for the thermal degradation of tyres in order to recover valuable components from rubber wastes.120-125 Stirred tanks, rotary kilns, fixed beds, fluidized beds and tray systems are examples of reactor types used for the thermal degradation of tyres. Several of these processes are now being used on a pilot plant and industrial scale. Basically, three fractions are derived from the thermal decomposition of tyres gases, liquid oils and solid residues. In the past, the influence of the reaction conditions and the reactor type were studied in order to maximize 

With respect to the solid residue, the authors observed an increase in the char surface area with both temperature and heating rate, values up to 60 m2/g being obtained. These surface areas are large compared with those of the raw carbon blacks used in tyre manufacture. However, the pyrolysis char contains a higher proportion of ash and has a larger particle size, which make this product an 

Various alternatives have recently been proposed for the valorization of the solid carbon residue of tyre pyrolysis. Napoli et al.ni have compared the properties of the char with those of coal. The calorific value of the char is slightly higher than that of coal due to the lower ash content of the former, while 

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