GB914064A - Process for separating particles of solid material into fractions according to specific gravity - Google Patents

Abstract

914,064. Washing granular materials. STAMICARBON N.V. Dec. 2, 1959 [Sept. 2, 1958], No. 28210/58. Class 82 (2). In a sink and float process a mixture of materials of different specific gravity is separated into coarse and fine fractions, the coarse fraction is then separated into fractions of different specific gravity by treatment in a suspension of magnetizable particles and the fine fraction is separated in a liquid medium of lower specific gravity than the first suspension, the coarse particles being washed with water from the fine fraction separator and the magnetizable particles recovered by a magnetic separator for recirculation to the coarse fraction separator, and the non-magnetizable particles and liquid recirculating to the fine fraction separator. As shown, a coal feed of size up to 7 inches is wet screened at 1 and the coarse fraction is separated in a suspension of magnetite in a sink and float separator 11. The coal floats are screened at 12 and rinsed by sprays 13 and the sinks are screened at 16 and washed by sprays 17, the magnetite rinsings collecting in tanks 15 and 18 and passing to a magnetic separator 21 the magnetic fraction being recirculated to separator 11 and the remainder passing to sprays 2. The fine fraction from the raw coal feed passes from 1 to a jig 4 and the washed fine coal is dewatered on screen 6 and discharged at C while the underflow from 6 separates in cone 8 into a sludge D and the clear water overflow is partly returned to the jig 4 and also to the sprays 13 and 17 which wash the floats and sinks from the separator 11. If the screen 1 operates dry the non-magnetic particles from the magnetic separator 21 by-pass the screen, as shown at 24. In an alternative embodiment (Fig. 2, not shown) the jig 4 is replaced by a froth flotation plant. Specifications 791,520, 791,857, 791,858 and 791,859 are referred to.