Fundamental Study of Plastic Separation Utilizing Magnetic Force

In order to recycle the plastics, a new method to separate polyethylene (PE) and polypropylene (PP) by the magnetic separation using superconducting magnet was developed. Magnetic separation method is superior to other methods in continuous and high-speed processing. Most of the plastics are diamagnetic, which makes it difficult to separate using traditional magnetic separation method. Therefore, we used magnetic force in horizontal direction and magneto-Archimedes method, which can be applicable to paramagnetic or diamagnetic substances. We designed an apparatus to separate the plastics, and succeeded in separating PP selectively from the mixture of PP and PE, by levitating and moving in a horizontal direction by the magnetic force. We determined appropriate magnetic field source and the concentration of medium by calculation. We confirmed the possibility of magnetic separation of PP and PE by trajectory calculation and demonstrated the separation experiment. As the result, PP and PE were selectively separated by moving PP to the sidewall of the vessel while levitating.