By physical law, any metal piece crossing a variable magnetic field is subjected to a force which tends to repel it from the variable magnetic field source.

Therefore, by conveying a material composed of a mix of non-ferrous metals and non metallic pieces through a variable magnetic field, the two fraction materials will tend to be sorted apart from each other.

The variable magnetic field on an eddy-current separator is mechanically created by means of a magnetic head pulley, presenting rows of alternate polarities (North-South) around its circumference, and rotating inside a shell (drum) on which a conveyor belt runs.

With the magnetic pulley rotating at a much higher speed than the one of the shell (belt) makes that material, laying on the belt, passes over the magnetic head pulley area, crossing the fast succession of the alternate polarity rows which act as the source of the variable magnetic filed.