Triboelectrostatic separation of covering plastics in chopped waste electric wire

Abstract

To develop a triboelectrostatic separation technique for covering plastics in waste electric wire, process variables such as charger material, relative humidity, air velocity, electrode potential, and splitter position have been studied. Polypropylene was found to be the most effective material for a tribo-charger in the separation of cross-linked polyethylene (XLPE) and polyvinyl chloride (PVC). The charge density of XLPE and PVC was increased with deceasing relative humidity and increasing air velocity in the tribo-charger. The charge density of a 1:1 mixture of XLPE and PVC was determined to be higher than that of individual XLPE and PVC. A dominant charging mechanism in the tribo-charger with a 1:1 mixture of XLPE and PVC seems to be the charging of a combination of particle-particle and particle-charger surface. However, in case of individual plastics, the charging of particle-particle occurred. Over 98.05% PVC recovery with 99.50% grade was successfully obtained under the conditions of a splitter position of +2 cm from the center, 25 kV electrode potential and over 13 nC/g PVC charge density for the optimum triboelectrostatic separation. POLYM. ENG. SCI., 47:1975-1982, 2007.