Installations for the neutralization of granular insulating materials obtained by electrostatic separation

Preventing accumulation of static charges and finding means for its elimination have been topics of active research in the field of electrostatic separation technologies for granular mixtures of insulating mixtures. Four installations are examined as potential solutions for the neutralization of the residual charges in separation processes. The experiments are performed with mm-size granules of Acrylonitrile Butadiene Styrene (ABS) and High-Impact Polystyrene (HIPS) recovered from industrial wastes. The granules are corona charged at a potential similar to that acquired by triboelectric effect. They are spread across an electrode connected either to the ground or to a high voltage (HV) of opposite polarity, then exposed to either DC or AC corona, in view of neutralizing the residual charge. The use of AC corona gives the best results, attaining neutralization rates as high as 95.3 % for ABS and 87.3 % for HIPS granules.