MECHANICAL SEPARATION-ORIENTED CHARACTERIZATION OF ELECTRONIC SCRAP

The ever-increasing amount of electronic scrap and the steadily-decrea sing contents of the precious metals used in electronics, as well as t he ever-growing environmental awareness, challenges such conventional precious-metal-oriented recycling techniques as pyrometallurgy. Separa tion and beneficiation of various materials encountered in electronic scrap might provide a correct solution ahead. In this context, mechani cal separation-oriented characterization of electronic scrap was condu cted in an attempt to evaluate the amenability of mechanical separatio n processes. Liberation degrees of various metals from the non-metals, which are crucial for mechanical separation, were analyzed by means o f a grain counting approach. It is found that the metallic particles b elow 2 mm achieve almost complete liberation. Particle shapes were als o quantified through an image processing system. The results obtained show that the shapes of the particles, as a result of shredding, turn out to be heterogeneous, thereby complicating mechanical separation pr ocesses. In addition, separability of various materials was ascertaine d by a sink-float analysis. It has been shown that density-based separ ation techniques shall be viable in separating metals from plastics, l ight plastics (ABS, PS and PVC, etc.) from glass fiber reinforced resi ns and aluminum from heavy metals. Specifically, a high quality copper concentrate can be expected by density-based separation techniques. M oreover, FT-IR spectra of plastics pieces from the light fractions aft er the sink-float testing show that PC scrap primarily contains ABS, P S and PVC plastics with the density range of + 1.0-1.5 g/cm(3), wherea s PCB scrap mainly contains glass fiber reinforced epoxy resins plasti cs with the density range of + 1.5-2.0 g/cm(3). (C) 1997 Elsevier Scie nce Ireland Ltd.