Principle- This method is based upon magnetism
Process –In this process powdered ore is allowed to fall through hopper on leather or rubber belt which is constantly moving over two rollers one of which is electromagnetic in nature. The magnetic particles present in the ore when come in contact with the magnetic field of the electromagnetic roller they get attracted towards the roller and hence get collected near the roller, while non magnetic particles present in the ore are not attracted towards the roller hence fall away from the roller.
e.g. 1.concentration of magnetic ore like Haematite which contains non magnetic impurities 2. concentration of non magnetic ore like Tinstone which contains magnetic impurities