GB994351A - Separation of materials - Google Patents

Abstract

994,351. Centrifugal separators ; separating solids. COAL INDUSTRY (PATENTS) Ltd. Aug. 25, 1961 [May 27, 1960], No. 18864/60. Headings B2H and B2P. Granular solids of different densities are separated, using a dense medium as a carrier, in a separating vessel from which a first discharge including dense medium and the less dense solids is led away and a second discharge including dense medium and the denser granular solids is led into a secondary vessel in such a manner that it is caused to move spirally inwards towards the vessel axis prior to passing through its outlet, no separation taking place between the dense medium and the granular solids in the secondary vessel. In Fig. 4, the solids in a carrier medium are introduced at 12 tangentially under pressure in a cylindrical separator 10. The light fraction, with part of the carrier medium, escapes through a vortex tube 13. The heavy fraction, separated under the action of centrifugal force, passes with another portion of the carrier medium from the periphery of the separator to that of a secondary vessel 14 in which it moves spirally towardsa central outlet. The separator is provided at its top with a vent tube 15 or, alternatively, with a funnel for admission of more granular solids with or without carrier medium. In Fig. 6, the solids and the carrier medium enter the separator at 12. A light fraction leaves at 13, a fraction of intermediate density at 17 and a heavy fraction through the conduit 9 tangentially into the secondary vessel 14. Additional carrier medium, which may be of density greater than that at 12, may be fed at 18. In Figs. 7 and 13, the solids and the carrier medium enter at 12. The light fraction leaves at 13, and a heavy fraction passes into a secondary vessel 14. An intermediate fraction passes from the outer periphery of the cylindrical bottom of the separator 10 into another seondary vessel 20. Alternatively the separator 10 may be cylindrical. One or more inlets 18 may be provided for the supply of additional carrier medium at densities and in quantities regulated so as to maintain the desired density of medium in the various separating zones of the vessel 10. Alternatively, the carrier medium supplied at 12 is unstable so that under the action of centrifugal force the density of the medium increases in the zones further removed from the axis. In Fig. 3, the solids and the carrier medium are introduced at 12 into a settling tank 10. Part of the carrier medium together with the solids that float overflow at 11 while the heavier solids and the rest of the carrier medium are led via a conduit 9 to the secondary vessel 14. A further inlet for supplying more carrier medium to the tank 10 may be provided. In another embodiment, the apparatus may be as described in Fig. 1 of Specification 769,429 with a secondary vessel connected to the base of the part 7, a water connection being made either to the part 7 or to the secondary vessel. In a further embodiment, a secondary vessel is connected to the bottom of pipe 8 of the apparatus described in Specification 919,342 instead of the pump 31.