The application of thermal processes to valorise waste tyre

Scrap tyres are a growing environmental problem because they are not biodegradable and their components cannot readily be recovered. In this investigation, the thermochemical recycling of rubber from old tyres by pyrolysis and the value of the products obtained have been studied. First, thermobalance experiments were carried out, studying the influence of the following variables: heating rate, flow rate, particle size and temperature. These thermobalance results were extended by performing experiments in a fixed bed reactor, studying the effect of the main process variables on yields of derived products: oils, gases and solid residue. The oils have been characterized using a combination of analytical techniques (TLC–FID, GC–MS and simulated distillation). No relationship between functional group composition of the oils determined by TLC–FID and process variables was found. The carbonaceous material obtained was characterized by N2 and CO2 adsorption. The possible uses of this char have been analyzed taking into account and calculating the emissions that would be produced if the char were burnt.