A rotating magnetic field in the drum generates eddy current in each electric conductive ash part (non-ferrous metal), which will then generate another magnetic field. The magnetic ash part will then be repelled from the drum and the non-ferrous metals can be separated reliably.
The quality of the non-ferrous separation depends on several parameters:
Specification of the installed non-ferrous separator:
Development Project: Efficiency Increase of the Eddy Current Separator
Additional separation of NF metals from the fine bottom ash
Report (in German only)