GB538400A - Improvements in apparatus for gravity separation of granular material - Google Patents

Abstract

538,400. Separating coal, ores &c. HIRST, A. A., and SIMON-CARVES, Ltd. Dec. 30, 1939, Nos. 33091/39 and 15624/40. [Class 82 (ii)] In a method of separating granular materials such as coal or ores in a fluid suspension of intermediate specific gravity, the density in the separator is maintained by returning to the separator a mixture of thickened suspension and clarified liquid mixed automatically in the required proportions. In the plant shown the material to be separated is fed by a shoot 14 to a separator 7, which may be of the form described in Specifications 530,787 and 531,822, and the separated materials are drained on screens 19, 21, the suspension collected in the vessels 22 being passed to a tank 5 from which it is pumped back to the separator through a pipe 77. Dilute suspension resulting from spraying the products on the screens 19, 21 passes through pipes 27 to a tank 28 from which it is pumped to a thickener 30, thickened suspension from which is conditioned in a counter-balanced vessel 35 by agitating it with air supplied through a pipe 48. The size of the interchangeable nozzle 33 is such that the suspension passing therethrough is denser than that normally in the separator. If the density in the vessel 35 falls, the vessel rises, and its overflow passes to the tank 28, the same operation moving a flexible pipe 41 to direct the overflow from the thickener 30 through a pipe 47 to the tank 25 from which the sprays for the screens 19, 21 are supplied; if the density in the vessel 35 is sufficiently high its overflow passes to the tank 5. A float 64 in the vessel 5 operates a flexible pipe 59 to direct overflow from the thickener 30 either to the vessel 5 or to the tank 25; overflow from the thickener 30 also passes through a pipe 4 to the tank 25. In modifications, means are provided for automatically diverting to the tank 28 the flow of thickened suspension from the vessel 35 during the time clarified liquid is being admitted to the tank 5; or the admission of clarified liquid to the tank 5 may be controlled step-by-step through an arrangement of ratchets operated electromagnetically from the float 64; the float 64 instead of being in the vessel 5 may be in other positions such as at 105 or 106 in the separator 7, or in a pipe such as 77; and means may be provided for circulating the suspension within the tank 5.