Pyrolysis of electrical and electronic wastes

A preliminary study of the possibilities of pyrolysis for recovering wastes of electrical and electronic equipments (WEEE) has been carried out. Four type of samples coming from real WEEEs streams, including wires of polyethylene (PE), table phones, mobile phones and printed circuit boards (PCB) have been pyrolysed under nitrogen in a 3.5 dm3 autoclave at 500 °C for 30 min. PE wires yield 44.1 wt.% of wax-like liquids, 23 wt.% gases and a solid product mainly composed of Cu and Al together with some char formed during the process. Table and mobile phones give quite similar results, 53 and 57 wt.%, respectively of brown-coloured fluid liquids, ≈12 wt.% gases and a solid which contains several metals (Cu, Al, Fe, Zn, Ni, etc.) together with a significant amount of char (≈50% with respect to solids). Printed circuit boards yield only 16.2 wt.% brown-coloured fluid liquids and 7.3 wt.% gases, and leave 76.5 wt.% of solids which include a wide variety of metals (from Fe to precious metals) which are present in the original circuit board waste. In all the cases the polymer-free metals may be separated and recycled, the gases may be enough energy sources to self-sustain the process and the liquids may have a potential use as energy or chemicals source.