GB912101A - Magnetic method for removal of finely divided magnetic materials - Google Patents

Abstract

912,101. Magnetic separators. CORSON Inc., G. & W. H. Feb. 14, 1961, No. 5387/61. Class 117. A mixture of finely divided magnetic and non-magnetic particles, such as fly ash, having a particle size smaller than 100 mesh, is separated by introducing the mixture, by a conveyer belt 44, into a rotating magnetic field produced either by rotating permanent magnets, Fig. 1, or by polyphase A.C. excitation of electromagnets comprising a number of polepieces such as 60A-60C, 62A-62C, 64A-64C, 66 and 68, Fig. 6, the field having a mean maximum intensity adjacent a non-magnetic surface of at least 20% of the mean coercive force of the magnetic particles and not more than 2 webers per square metre and a field gradient across its depth of from 0.3 to 40 webers per square metre per metre, and said field having a mean speed of rotation of from 150 to 10,000 radians per second whereby the magnetic particles are caused to spin and collide with the non-magnetic particles to produce a turbulent expanded state of the mixture with the non-magnetic particles being ejected from the field into a collecting trough 88 whilst the magnetic particles are retained in the field and caused, by their rotation, to travel therealong away from the feed belt 44 and to concentrate at the remote end of the field from where they fall into a trough 92. The polepieces 60-68 are covered by a non-magnetic sheet 58 which may be arranged as a travelling endless belt to assist movement of the magnetic particles towards the collecting zone. Alternatively a gas stream may be employed in conjunction with the stationary sheet 58. As shown the polepieces are electrically excited by a three-phase A.C. supply, the pieces of each A, B or C set being connected in series and each series being Y or delta connected to give a 120-degree phase angle between poles. Other phase angles may be used if desired.