High-gradient magnetic separation using ferromagnetic membrane

• A new design of magnetic separator with ferromagnetic membrane was developed.
• Coarse magnetic particles 1 μm in size are captured by the membrane preferably.
• Selectivity of magnetic separation improves with flow rate decrease.
• Separation efficiency of thick ferromagnetic membrane is higher than of the thin one.

The magnetic separator with the membrane separating unit made of laser-perforated thick ferromagnetic foil was tested using composite water suspension of magnetic nanoparticles adsorbed on hydroxylapatite microparticles. The average sizes of the particles in the suspension and the magnetic moment of the suspension were measured by dynamic light scattering and electron magnetic resonance correspondingly to evaluate the efficiency of the separation. It was shown experimentally that the separation is effected by the membrane type and the flow rate. Magnetic coarse grains (larger than 1 μm) were captured by the membrane preferably and the magnetic moment of the suspension decreased by 20–25% after the separation. The magnetic field simulation and experimental results demonstrate the higher separation efficiency for thicker membranes.