Recent progress in electrostatic separation technology

The applications of the electrostatic separation technique employed in the various field was overviewed. By classifying the electrostatic separators with the charging method and with the kind of sorting equipment, recent progress in the electrostatic separators was presented and also future trend was discussed. Principle and practical structure of the separator employing corona charging and induction charging was described in detail. Basically these charging and separation methods are applied to the materials with large difference in conductivities. Triboelectrification has been employed to charge the materials with little difference in conductivities. This is the case of the separation of reusable plastic material from plastic mixture and of minerals or ash contents from coal powder. Triboelectric charging is a key technique and the variety of a tribocharger for coal cleaning was presented. As an example of a practical separator, recent prominent recycling technology of copper and resin from printed wiring boards in the electronic circuits was introduced. Electrostatic remover of tea stalks and foreign objects from product in food industry were also discussed.