Separating magnetic particles from liquid slurries - having pre-treatment in magnetic field to cause agglomeration of fine particles

摘要

Process for altering the relative size of particles with different magnetic susceptibilities which are together in a liquid slurry involves passing the slurry through a magnetic field of sufficient strength and for a long enough time to cause individual particles of the more magnetic material to agglomerate. This is done prior to feeding through a separator containing a magnetisable packing (e.g. wire mesh) in a magnetic field which retains the magnetic particles. A flocculating agent is added to the slurry before it is processed. The agglomerate particles have a size 10 mu m. The magnetic ones have a susceptibility of between 10-5 and 10-3 (in S.I. units). A field strength between 1 and 10 Teslar is used with a residence time of longer than 2 sec. For use in separation systems where magnetisable material (esp. ferrous material) is separated from particulate slurries. If the ferrous material is very finely divided, then separation is poor esp. where the non-magnetic particles are larger than the magnetic ones. The system described improves thsi separation by causing agglomeration of the magnetic particles.