Experimental investigation of a modified free-fall tribo-electrostatic separator with rotating electrodes

The impacts of the plastic particles on the vertical electrodes of the free-fall tribo-electrostatic separator (FFTES) is one of the main drawbacks of this separator for sorting millimeter-size particles. The impact on the electrode causes in general a strong reflection of the particles causing the decrease of the separation purity because the particles impacting with the electrode are ejected further toward the compartment of the other material. This paper is aimed to investigate a modified FFTES configuration with rotating cylindrical electrodes instead of flat vertical electrodes to overcome the particle impacting effect. An experimental and a numerical analysis were carried out in which the main significant factors were investigated. The experiments carried out using binary mixtures of mm-size particles showed that the rotating electrodes attenuates considerably the reflection velocity in the horizontal plane causing a significant increase of the separator performance in terms of purity and recovery rates.