Pyrolysis: A “Recycling” Option for Automobile Shredder Residue

The recyclability of old automobiles is of major interest to auto manufacturers, original equipment manufacturers and regulatory bodies concerned about sustainable development. While the majority of the ferrous and non-ferrous metals are currently recycled, the non-metallic waste fraction generated by automobile shredding operations is currently disposed of in landfills. In view of the relatively large concentration of plastics and rubber in this material, pyrolysis, the thermal degradation of polymeric materials to predominantly hydrocarbon products, appears an ideal resource recovery option for this waste stream. In this study, the results of pyrolysis experiments performed in our laboratory will be examined and compared with pyrolysis data reported in the literature. The importance of pyrolysis temperature, pyrolysis reaction time and pyrolysis process design on product formation (liquids, solids and gases) as well as chemical composition are compared. The results suggest that while the pyrolysis of automobile shredder residue (ASR) is a technologically viable process, its acceptance as a commercial solution to the ASR waste stream in Canada depends upon other factors; such as:

• markets for the products of pyrolysis
• demonstrating that the technology is:
  1. socially
  2. environmentally
  3. economically
  4. and politically sound

Based upon the pyrolysis information collected, life cycle assessment (LCA) has been used to compare the pyrolysis option with other recycling disposal options available to deal with this current waste stream.