GB655957A - Improvements in and relating to the separation of raw coal - Google Patents

Abstract

655,957. Washing coal. DIRECTIE VAN DE STAATSMIJNEN IN LIMBURG. March 13, 1948, No. 7710. Convention date, March 14, 1947. [Class 82(ii)] In a method of washing coal using a cyclone, the fractions leaving both base and apex of the cyclone are sieved to remove large particles of coal and stone respectively and the remaining suspension returned to the cyclone after the finest particles of coal have been removed by froth flotation. An installation for carrying out the above method comprises a cyclone 1, into which the coal to be washed is fed as a suspension at 2, the coal 3 being fed on to a sieve 6 and the stones 4 fed on to a sieve 5. The small particles of low specific gravity, which are drained from the coal into the collecting tank 21, are conducted by pipe 20 and sprayed on to the stones fraction. Both coal and stones fractions are then sprayed with water at 8 and 9, and the small stone particles from the collecting tank of sieve 5 and small coal particles from collecting tank of sieve 6 are conducted by pipes 12, 13 to the froth flotation machine 14, the small particles of coal then being carried off with the froth at 15 and the small particles of stone taken out by pipe 16 via a pump 17 back to the cyclone. The coal to be cleaned is fed into a tank 18 and is also pumped via pipe 16. The concentration of the solids removed from the froth flotation machine can be varied by varying the level of the outlet 19. Alternatively the outflow 12 from the sieve 5 may be arranged to pass at 12<SP>1</SP> into the flotation tank outlet 16. The specific gravity of liquid may also be varied by varying the relative quantity of rinsing waters at 8, 9 the total quantity remaining the same. Specifications 215,615, [Class 82(ii)], 601,063, 639,229 and 655,945, are referred to.