elektroerottelua

Elektroerottelu is a separation technique that uses electric fields to separate particles based on differences in electrical properties such as conductivity, permittivity and chargeability. It is commonly used in mineral processing and materials recycling to separate minerals or plastics that have contrasting electrical properties. The method is typically performed in a dry or semi-dry form, though wet variants exist.

Principle: In electrostatic separation, particles are charged by tribocharging or corona discharge before entering a region with a strong electric field. The charged particles are deflected along trajectories that depend on their charge-to-mass ratio, conductivity and polarizability. Conductive and non-conductive fractions may follow different paths, enabling their collection in separate streams. Performance is influenced by particle size, shape, density, moisture content, charging efficiency and the surrounding medium, with humidity and air gaps affecting charging and discharging dynamics.

Equipment and process: Common configurations include drum-type, belt-type or roll-type separators and plate or grid collectors. The sample is prepared (screened or conditioned), charged, and fed into the electric field where separation occurs. Collected fractions are discharged separately. Key operating parameters are the applied voltage (often several kilovolts), feed rate, particle size range (ranging from tens of micrometers to a few millimeters) and humidity control.

Applications: Elektorertelu is used for ore beneficiation (separating conductive sulfide minerals from non-conductive gangue), coal cleaning, and recycling of plastics and electronic waste where fractions differ in conductivity. It is also applied in some glass, ceramic and environmental remediation processes.

Advantages and limitations: Benefits include chemical-free operation and the ability to exploit large contrasts in electrical properties. Limitations include sensitivity to particle size and moisture, charging efficiency, and limited effectiveness when conductivity differences are small; equipment costs can be considerable and performance requires careful process control.