Magnet Configurations For Improved Separations Of Magnetic And Non-Magnetic Materials

Magnetic separation of a mixture of magnetic and non-magnetic liquid phases is needed for such applications as cleaning up oil spills by separating oil and water liquid phases, or by separating magnetic materials from non-magnetic materials in biomedical and microfluidic applications.Most magnetic separation techniques work on the single principle of applying a nonuniform magnetic field in a single flow channel to direct the magnetic phase/particles to one side of the channel for separation. Inlet velocity/pressure, phase volume fraction and viscosities, magnetization of the magnetic phase and applied magnetic field strength are some of the parameters for efficient separation. A varying concentration of either the magnetic or non-magnetic components in the mixture adds to the difficulty of separation and can result in contamination of the separated components.The Kelvin magnetization force density that drives separation requires a spatial non-uniformity in the magnetic field. Non-uniform magnetic fields can be generated but are also inherent to edges of permanent magnets. This work describes using nonuniform magnetic fields, generated by edges of permanent magnets, for the magnetic separation in a mixture of non-magnetic and magnetic liquid phases. In addition, this work describes the use of a one-sided magnetic flux configuration (Halbach array) to increase the efficiency of separations.