Recycling of automobile shredder residues by means of pyrolysis

Automobile shredder residues (ASR) are the rejection of the present processes of metal recovery of end-of-life vehicles. They are composed of several plastics, foams, glasses, rubbers, textiles, remaining metals, soils, etc., and have no clear recycling alternative. In the pyrolysis process (heating to moderate temperatures without oxygen), the organic volatile matter of the waste (plastics, rubber, etc.) is decomposed to gases and liquids, which can be useful as fuels and/or chemicals source. The inorganic components (fillers, metals, glasses, etc.) can be recovered and reused. Therefore, pyrolysis is especially appropriate for recycling complex wastes, such as ASR. In this paper an experimental study of pyrolysis of real ASR samples coming from an autornotibile shredder plant (light and heavy ASR) have been studied. The pyrolysis experiments have been carried out in a non-stirred batch 3.5 dm(3) autoclave at 400, 500 and 700 degrees C for 30 min. The raw samples, as well as the solid, liquid and gaseous pyrolysis products have been thoroughly characterized. It is concluded that pyrolysis appears to be an appropriate technique for recycling the heavy ASR, since valuable solids (38-39%), liquids (20-29%) and gases (31-41%) are obtained, while this is not the case for the light ASR, which does not yield valuable products. Concerning temperature 500 degrees C is enough to produce total decomposition of the ASR organic matter. Increasing temperature over 500 degrees C increases gases to the detriment of liquids, but hardly varies the characteristics of the products. (C) 2006 Elsevier B.V. All rights reserved.