Electrostatic separator free-fall

Electrostatic-Separation Machines The first electrostatic machines to be used commercially employed the principle of contact elec trification. These were free-fall devices incorporating large vertical plates between which an electrostatic field was maintained. Tribo-elec tric separation (contact charging) has experienced an increase in apphcations due to advances in mechanical self-cleaning and electrical design as well as the development of efficient precharging techniques. 

In general, all electrostatic separator systems contain at least four components (i) a chargingdischarging mechanism (ii) an external electric field (iii) a nonelectrical particle trajectory device and (iv) feed and product collection systems. Depending primarily on the charging mechanism involved, the electrostatic separator systems are classified into three categories (i) free fall separators (ii) high tension separators and (iii) conduction separators. 

Charging by contact electrification is an active mechanism whenever dissimilar particles make and break contact with each other, or whenever they slide over a chute or an electrode. This charging mechanism is most frequently used to charge selectively and obtain an electrostatic separation of two species of dielectric materials as realized in a free fall electrostatic separator. 

Electrostatic separation, of a granulated mixture of polymers from electronic products, can separate polymers of similar density. The particles are charged by passing through an inclined rotating drum, then separate during free fall between two charged plates. 

Tilmatine A, et al. Roll-type versus free-fall electrostatic separation of tribocharged plastic particles. Electrostatic joint conference 2009. 

Figure 7.3.10. (a) Free-fall electrostatic separator with vertical plates (b) free-fall electrostatic separator with inclined vertical plates. (After Wei and Realff (2003).) (c) Drum-type electrostatic separator (d) tubular free-fall separator. (After Beier and Stahl (1997).)... 

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