Abstract
A discussion is presented, describing the published designs of magnetic of hydrocyclones and the outcome of using them to separate magnetite–sand mixtures. The designs fall into two groups: first, where magnetic–susceptible particles are attracted to the centre of the cyclone and are discharged through the overflow and secondly, where particles are attracted to the outer cyclone wall from where they exit via the underflow. This report also covers theoretical assessments of magnetic hydrocyclones; included is a modelling study, detailing how the resultant force experienced by the particles would vary with the number of magnetic poles incorporated in the hydrocyclone design. At the end of the paper, a new project is introduced, based on the conclusions of the above studies. This will use powerful rare–earth–type permanent magnets to provide high field values and gradients. With this approach it is hoped to overcome the difficulties encountered with previous designs.