Recovery of products from industrial waste streams for recycling

Purely mechanical processes, involving crushing/shredding of end-of-life objects before melting them into granules represent an older approach and are not capable of removing impurities chemically bound in the original structure of the recycled object; a typical example is constituted by pigments, dyes or other substances used to colour or to otherwise modify the properties of the original object. Plastics recycled this way have therefore restricted use, limited to products of inferior quality.