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The distribution of magnetic fields and an analysis of the separation in process in a spiral separat |
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The distribution of magnetic fields and an analysis of the separation in process in a spiral separater Author: M. Brożek
In the magnetic separation of strongly magnetic, fine-grained minerals the forces of magnetic and surface interaction between particles play a significant role. These forces lead to the phenomenon of magnetic flocculation. Non-magnetic particles are held in the floe volume and these, transfered to the magnetic products, lower the quality of concentrate. In order to reduce the effects of this phenomenon, special separators with an alternating magnetic field have been constructed or, the movement of the particulate mixture through the a constant magnetic field, a system of pole shoes of alternate polarity is employed. In the latter type of separators the particles of the aggregates are subjected to several magnetization cycles, in the course of which the non-magnetic components are precipitated. A spiral separater is a separation system using a series of magnetic fields with constant polarity. The paper discusses the principles of operation of this type of separater and determines the distribution of the magnetic fields and magnetic force in the separator's working space by means of conformal mapping. Following this the value of separation magnetic susceptibility was calculated from the balance of external forces acting on the particle. Applying the stochastic model of magnetic separation, the author has evolved an expression for a constant rate of separation and content of magnetic component in the concentrate, the yield of the concentrate as a function of the angle of inclination of the separater, the amount of washing water supplied, the number of helix rotations and the intensity of the external magnetic field. The dependence of the Fc content in the concentrate on the amount of washing water was verified experimentally. It was observed that surface interactions between particles should be taken into consideration when a full correlation between the model and experimental values is required.
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2011