Open-gradient Magnetic Separator With Racetrack Coils Suitable for Cleaning Aqueous Solutions

Superconductivity enables magnetic fields in a magnitude of 5-10 times greater than conventional electromagnets. Applied to magnetic separation, use of superconducting magnets opens the possibility to separate sub-micron sized paramagnetic particles. Open-gradient magnetic separation (OGMS) enables continuous operation without the need of matrix-elements. Such a separator consisting of liquid helium cryostat and an Nb₃Sn coils were designed and constructed for testing the separation of various slurries. The separation parameters, such as size and magnetic susceptibility of particles to be separated, applied magnetic force density, and flow velocity have to be experimentally optimized. In isodynamic separation, high gradient and nearly constant and homogenous magnetic force density distribution in separation zone are created by magnet design. Here the superconducting OGMS was used in purification of synthetically made solutions emulating industrial wastewaters. Performance of the used Nb₃Sn magnet is discussed and proposals for developing the performance of racetrack magnets are given. Finally, a simple permanent magnet separator was constructed and tested with wastewater