Nonferrous metal separators for small particles

Eddy-current separation becomes inherently more difficult as the particle size decreases, because the eddy-current induced force diminishes with decreasing particle size. The present paper describes two new types of nonferrous metal separators which are specifically designed for particles with diameters of the order of 1 to 5 mm and use permanent magnets to induce eddy currents. One of the separators, the "channel separator" consists of two inclined steel plates with magnet arrays on the two sides facing each other. The magnet material used in this case is rubber base barium ferrite with a magnet period of 1/4". The separation of the two steel plates can be varied. The other separator, the "rotary disc separator," uses SmCo5magnets that are attached to two discs which are turned at high speed. The results of tests on various kinds of waste such as shredded communications cables and shredded plastic beverage containers (with A1 contamination) are reported.