Conclusions to Chapter 2

1. The corona charging experiments carried out with millimetre-size PVC and polyamide disks on the surface of a grounded electrode point out several aspects that should be considered in the design of new electrostatic separation technologies.

1.1. The charge acquired by the insulating particles depends on their shape and size, but also on their density on the surface of the carrier electrode. The feed rate should be chosen such that the material to form a uniform monolayer on the surface of the roll electrode, with particles slightly distanced from one another.

1.2. Homogeneity of particle size is a prerequisite for uniform discharge conditions. An effective electrostatic separation should be preceded by the classification of the material to be processed.

2. Computer based instrumentation improves overall experimental accuracy. The experiments prove that the VI developed for monitoring the powder tribocharge is an effective SPC tool.

3. By sampling, at well-established time intervals, the charge of the powder collected in a modified Faraday cup, it is possible to build up SPC charts that appropriately reflect the output of the respective processes.