· By , R&D and Sales Director, Lenoir-MEC

Eddy current separator: principle and applications

How an eddy current separator works, which non-ferrous metals it recovers and how to install it in a sorting line.

In brief

  • An eddy current separator recovers conductive non-ferrous metals (aluminium, copper, brass) mixed with inert materials such as plastic, glass, wood or paper.
  • A permanent magnet rotor spinning at high speed (5,000 rpm on the PELICAN) induces currents in the metals, which are repelled out of the material flow.
  • It is installed after an overband magnet or a magnetic drum, which first removes the ferrous metals.

The eddy current principle

The separator relies on a high-intensity magnetic field generated by a magnetic rotor housed inside a non-magnetic drum at the discharge end of the belt conveyor.

  • High-speed magnetic rotor: fitted with permanent magnets, it rotates at variable speed and creates a powerful alternating magnetic field.
  • Electromagnetic induction: when aluminium, copper or brass pass through this field, electric currents, known as eddy currents, are induced in the pieces.
  • Magnetic repulsion: these currents create a field opposing that of the rotor; the repulsive force ejects the non-ferrous metals along a separate trajectory.
  • Adjustable splitter: it separates the two trajectories; plastics, glass and wood follow their natural trajectory and are collected separately.

The size, shape, density and electrical conductivity of the particles influence their behaviour during separation.

Applications

  • Metal recycling: non-ferrous metals from shredding and material processing.
  • Industrial waste, municipal solid waste and sorting plants: non-ferrous metals present among plastic, glass, wood or rubber.
  • Automotive recycling: aluminium and other non-ferrous metals from automotive shredder residue (ASR).
  • WEEE recycling: non-ferrous metal fractions from waste electrical and electronic equipment.
  • Incinerator bottom ash (IBA), slag, ores and quarry residues.
  • Recovery of aluminium from mixed plastics.

Steps for efficient separation

  1. Remove ferrous metals upstream: an overband magnet or a magnetic drum placed before the separator improves the purity of the non-ferrous fraction, reduces belt wear and extends the service life of the rotor.
  2. Feed in a thin, uniform layer: the material must be spread across the full belt width; a vibratory feeder helps achieve this distribution.
  3. Respect the rated throughput: overloading the conveyor reduces separation quality and increases belt wear.
  4. Adjust the rotor and the splitter: rotor speed and splitter position are adapted to the type and particle size of the materials.
  5. Maintain the rotor and the drive: periodic preventive maintenance keeps performance at its best.

Lenoir-MEC equipment

Related sectors: recycling, glass and ceramics, mining and quarrying. See also: choosing an overband magnet and our article eddy current separators, the essential technology for recycling.

Frequently asked questions

Which metals does an eddy current separator recover?

Conductive non-ferrous metals: aluminium (cans, profiles, foils), copper and brass.

Why remove ferrous metals before the eddy current separator?

Processing a stream from which ferrous metals have already been removed by an overband magnet or a magnetic drum improves the purity of the recovered non-ferrous metals, reduces belt wear and extends the service life of the rotor.

How can the purity of recovered aluminium be improved?

Feed the separator in a thin, uniform layer across the full belt width, for example with a vibratory feeder, and do not exceed the rated throughput.

A non-ferrous sorting project?

Describe your material stream (type, particle size, throughput): our engineering department will size the right eddy current separator. Request a quote