Superconducting open-gradient magnetic separator utilizing the braking effect of an axial component of magnetic force

The computer simulation of particles' trajectories in a simple cylindrical coil shows that the magnetic force acting on paramagnetic particles at the bottom part of the coil bore has a predominantly axial component which aims upwards and opposite to the force of gravity. In case of a superconducting coil and depending on the value of the particle mass susceptibility, the axial force component can exceed several times the force of gravity. As a result, an expressive braking of the motion of particles in the vertical downwards direction appears. This effect was utilized in an unconventional design of magnetic separator, the main advantage of which is the high selectivity of separation process. The separator operates either in a deflecting or attracting mode. The cylindrical orifice feeder and the splitter are located in the warm bore of a liquid helium cryostat with the inner diameter of 140 mm. A Magnetic force field with a magnetic flux density up to 7 T is generated by the NbTi superconducting coil. The experiments with the siderite and quartz classified particles have been performed and compared with the theory.