Electrostatic separation refers to the selective sorting of solid particles by utilizing differences in the electric surface charges of the particles. Basically, the separator consists of a rotating drum and a plate which is located at some distance from the drum. A voltage is induced between the drum and the plate, forcing one to become negatively charged (e.g., the drum) and the other to become positively charged (e.g., the plate). As the feed (both valuable and waste particles) is introduced into to separator, the surface charge on the particles causes them to either be attracted to or repelled away from the drum. If the valuable minerals have a charge which is different from the waste minerals, they can be efficiently separated as shown below.

Figure: Electrostatic separator