Electrostatic separator particle trajectories

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. 

An important means by which small particles in suspension are separated from solutions is through capture by collectors, which may be larger particles, or granular, porous, or fibrous media. An example of such collection is filtration. The separated solids may be collected as a cake on the surface of the filter medium (much like ultrafiltration), and this is termed cake filtration. Alternatively, the solids may be retained within the pores of the medium, and this is termed depth filtration. It is important to recognize that particle collection in a porous medium is not simply a matter of straining that is, the capture is not purely steric, since, in filtration, particles are captured that are much smaller than pores of the medium. The capture of small suspended particles from fluids in laminar flow by a collector is a consequence of the simultaneous action of fluid mechanical forces and forces between the particle and collector, such as van der Waals or electrostatic forces. It is the combined forces, at least close to the collector, that govern the particle trajectories and determine whether a particle will be transported to and retained at the surface of a collector that is fixed in the flow (Spielman 1977). 

Derjaguin, Landau, Verwey, and Overbeek) theory addresses the interaction between pairs of particles based on the net influence of the repulsive forces that derive from the electrostatic forces, and the attractive forces that derive from van der Waals forces (Elimelech et al., 1998). The electrostatic forces act over relatively long distances, and result from the charge resident on the surface of the particles. The attractive van der Waals forces result from dipole—dipole interactions and act only at short distances. Thus, two particles that approach each other on a trajectory at separation distance, s, experience a combination of attractive, Vvdw. and repulsive, Vgs forces ... 

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