GB1029002A - A method and apparatus used for continuous concentration of magnetically responsive solids from non-magnetically responsive solids in a fluid medium - Google Patents

Abstract

1,029,002. Washing granular material; centrifugal separators. INSINOORITOIMISTOENGINEERING BUREAU R. T. KUKKI. March 18, 1964, No. 11468/64. Headings B2H and B2P. Apparatus for gravity separation of magnetic particles, such as hematite, from non-magnetic particles in a fluid medium comprises a vessel, Fig. 1, having a cylindrical top section 1, a conical middle section 2 and a cylindrical bottom section 3, an inlet 10 in the upper part of the apparatus for admitting the material to be separated and the medium at a selected rate, a rotatable shaft 4 having an impeller 5 within the middle section and a core 6 within the lower section, a magnetic system creating a field between pole pieces 19 and the core, an inlet 16 to introduce an upward flow of fluid medium through the magnetic zone in a countercurrent fashion, an outlet 9 below the magnetic zone for discharging the magnetic particles and means, such as outlet 14 and weir 11 for discharging non-magnetic particles from a level above the magnetic zone. The feed and liquid medium is introduced tangentially through the inlet 6 and is drawn into circular motion by the impeller 5 to form three layers 20, 21, 22, the particles of high S. G. falling to the bottom layer 22. Since hematite is of high S.G.,this material is concentrated in the bottom layer. The magnetic field increases the effective S.G. of the magnetic particles only and the medium flowing upwardly at a steady or pulsating rate from the inlet 16 carries non-magnetic particles not held strongly enough by centrifugal and gravitational forces upward into the upper rotating layers. Discharge of the magnetic particles is through a manually or automatically adjustable valve at the outlet 9. In another embodiment, Fig. 4, the feed is introduced down a central tube 23 and the conical middle section is formed of rubber and provided with a vibrator 30 and spirals 29 to promote stratification rather than sliding. In a further embodiment, Fig. 3, the feed is introduced down a central tube 23, the discharge from the middle layer 21 is through a central tube 24 and outlets 25, the conical wall is stepped at 27 to cause particle-rearrangement and additional medium is introduced through nozzles 28. The fluid medium may be water or a dispersion in water of fine solids, preferably hematite. Additional washing medium, either pulsed or introduced at a steady rate may be directed into the bed of particles. Discharge from various depths may be achieved by siphons. The cylindrical bottom section 3 is preferably made of rubber. Permanent or electromagnets 18 may be employed and the core 6 may be provided with ridges to insure maximum convergence of lines of flux, the spaces between the ridges being filled, if desired, with rubber; grooves of ridges may be arranged, instead, on the pole pieces 19. Various parts of the apparatus may be rubber lined or made entirely of rubber. Several apparatus may be arranged together in parallel or series.