Electrostatic Separation of Valuable Metals From Finely-Ground WEEE

Waste electrical and electronic equipment (WEEE) contain heavy metals (mercury, chromium, cadmium, lead, etc.) and halogen materials (bromine, chlorine, etc.), which are toxic for humans and harmful to the environment. WEEE are subjected to shredding and grinding operations, followed by magnetic, eddy-current, optical, and float-sink separation. Electrostatic separation could be added to existing WEEE processing systems to distinctly recover the constituents of such granular waste. The aim was to find viable technical solutions to the problem of electrostatic separation of mixtures of conductive and insulating materials in the recycling industry. The feasibility tests were carried out on representative samples of 200 g of finely-ground materials (size less than 5 mm) originating from the processing of WEEE, using a roll-type electrostatic separator to distinctly recover the conductive and insulating materials. The parameters relevant to the efficiency of the separation were the distance between the electrodes, the level of the high-voltage applied to them, the rotation speed of the drum, and the size of the particles. The quality of the separation was evaluated by measuring the recovery and the purity of the conductive fraction, which in some cases could attain almost 80% and more than 88%, respectively.