An eddy current separator uses a powerful magnetic field to separate metals from non-metals in garbage. The device makes use of eddy current

Eddy current

Eddy currents are electric currents induced in conductors when a conductor is exposed to a changing magnetic field; due to relative motion of the field source and conductor or due to variations of the field with time. This can cause a circulating flow of electrons, or current, within the body of...

s to effect the separation.

The eddy current separator is applied to a conveyor belt

Conveyor belt

A conveyor belt consists of two or more pulleys, with a continuous loop of material - the conveyor belt - that rotates about them. One or both of the pulleys are powered, moving the belt and the material on the belt forward. The powered pulley is called the drive pulley while the unpowered pulley...

 carrying a thin layer of mixed waste. At the end of the conveyor belt is an eddy current rotor. Metals are thrown off the belt, while non-metals simply fall off the belt due to gravity. Ferrous metals may cause damage to the separator, and they are usually removed from the waste stream magnetically before the eddy current separator is used.

Eddy current separators may use a rotating drum with permanent magnets, or may use an electromagnet. Depending on the type of separator, processed material may only be separated into metal or non-metal categories, or the processed metal stream may also be divided into ferrous and non-ferrous metals.