Optimisation of belt-type electrostatic separation of granular plastic mixtures tribocharged in a propeller-type device

Abstract

Electrostatic separation has already proven its efficiency as a method to recover metals and plastics from granular waste electrical and electronic equipment (WEEE). Nevertheless, there still is some work to do regarding the sorting of the various sorts of plastics (ABS, ABS-PC, HIPS, PC) contained in information technology wastes. The main objective of this paper is to optimize the electrode configuration and the operation of a belt-type electrostatic separator employed in conjunction with a new tribo-aerodynamic charging device. This application is particularly designed for the recovery of granular materials issued from shredding of computer cases, which contain large quantities of ABS. The following control variables were considered for the optimization: (i) distance between the axis of the high-voltage electrode and the surface of the grounded belt electrode; (ii) angular position of the high-voltage electrode with respect to the horizontal plane; (iii) high-voltage level. Experimental design methodology was employed for determining the optimum value of each variable, using commercial software (MODDE, Umetrics, Sweden).