Eddy current separator
An eddy current separator uses a powerful magnetic field to separate non-ferrous metals from waste after all ferrous metals have been removed previously by some arrangement of magnets. The device makes use of eddy currents to effect the separation. Eddy current separators are not designed to sort ferrous metals which become hot inside the eddy current field. This can lead to damage of the eddy current separator unit belt.
The eddy current separator is applied to a conveyor belt carrying a thin layer of mixed waste. At the end of the conveyor belt is an eddy current rotor. Non-ferrous metals are thrown forward from the belt into a product bin, while non-metals simply fall off the belt due to gravity.
Eddy current separators may use a rotating drum with permanent magnets, or may use an electromagnet depending on the type of separator.
A patent for a device using eddy currents to separate non-ferrous metals from non-metals was granted to William Benson and Thomas Falconer of Eriez Magnetics in 1969.