GB903846A - Improvements in or relating to magnetic separation methods - Google Patents

Abstract

903,846. Magnetic separation. ENGLISH CLAYS LOVERING POCHIN & CO. Ltd. July 25, 1960 [July 29, 1959], No. 26102/59. Class 117. In ,the magnetic separation of a mass of particles, a stream of fluid is passed through the mass to produce a fluidized bed, and the more magnetically susceptible particles are collected on a magnetic collector member. In Fig. 2, granular material to be treated is fed through an inlet 22 and air is passed upwardly through the material by way of a pipe 31 and a perforated plate 25. The particles are supported by the air stream in a state of turbulence and are subjected to the field of an electromagnet having poles 34, 35 which project into the separation chamber 20. Particles which are not attracted to the magnet poles pass through a conduit 26, and a valve 27 in the conduit is controlled by a device 40, in accordance with the difference between the pressures above and below the fluidized bed, as detected by a device 37, e.g. a manometer. To remove the particles attracted to the polepieces, the magnet is de-energized, the height of the fluidized bed is allowed to fall to zero and a swivel plate 28 adjusted such that the particles are discharged down a shoot 30 into a bin separate from the one which received the previously discharged particles. Alternatively, the particles collected on the polepieces may be discharged through an exhaust pipe 33. In a modification, Fig. 4, each member of a stack of magnetic collector grids consists of strips 41 of soft iron bent zig-zag and held in a non-magnetic frame 42. With this construction, the polepieces of the electromagnet may be disposed outside the separation chamber. Instead of using air as the fluidising medium, inert gases or liquids, e.g. water, may be used. The method is suitable for treating ground, calcined, refractory aluminium silicate to remove magnetic impurities emanating from crushing rolls. According to the Provisional Specification, the magnetic grids may be in staggered relation to one another. Instead of grids, spaced sets of parallel bars, the bars of one set being horizontal and those of the next vertical, may be employed.