THE USAGE OF THE PERMANENT MAGNET ASSEMBLIES FOR SEDIMENTATION OF DISPERSED PARTICLES IN AQUEOUS MEDIA

The magnetic separation technology is used in innovative water purification methods for pollutant removal from aqueous media. The efficiency of the magnetic separation depends on the characteristics of the non-uniform magnetic fields generated by magnetic systems, the properties of the aqueous medium, and the magnetic particles.
The influence of gradient magnetic fields generated by permanent magnet assemblies on sedimentation of Fe3O4–SiO2 nanoparticles in aqueous solutions with various viscosities was studied. Numerical modeling was used to calculate the Bz and |Bz·dB/dz| values under the surfaces of a permanent magnet, radial and plane-parallel assemblies made of Sm2Co17 permanent magnets, and soft magnetic steel. It was shown the areas of high values of |Bz·dB/dz| near the surface of the magnetic systems are produced by the assemblies M1 and M2 due to their complex geometries. The magnetic sedimentation efficiency (MSE) of nanoparticles in magnetic field gradients
generated by magnetic systems was studied. The MSE in aqueous solution with a viscosity of 0.89–3.07 mPa·s after exposure time during 30 minutes in the magnetic field of the radial assembly is more than 50%. To achieve the MSE more than 50% at using a plane-parallel assembly, it is required 1 and 5 hours exposure time for aqueous
solutions with a viscosity of 0.89 and 3.07 mPa·s, respectively. The MSE of nanoparticles are higher at using of the assemblies than the permanent magnet. In the areas of high values of |Bz·dB/dz| near the surface of the assemblies the particles velocities are increased, which accelerate the settling of magnetic nanoparticles.