GB389567A - Improvements in or relating to the separation of materials of different specific gravities - Google Patents

Abstract

389,567. Washing granular materials. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Chance, T. ; Merion, Pennsylvania, U.S.A.) Nov. 24, 1931, No. 32585. [Class 82 (ii).] In a process for separating coal, ores, or other granular materials from refuse in which the separation is effected in a high density fluid comprising a suspension of a finely divided solid such as sand in a liquid such as water, the suspension being maintained by mechanical or hydraulic agitation, means are provided to prevent the accumulation in the system of fine coal, ore, &c. either present in the feed or produced by attrition in the separating tank. Coal is fed over a screen 2 to a separating tank 3 containing a suspension of sand in water of sufficient density to float the coal while allowing the refuse to sink to a refuse chamber 5 controlled by valves 4. Coal, mixed with fine coal and the suspension liquid, overflows to a vibrating screen 7 from which the clean coal is discharged at 9 while the refuse is discharged from the chamber 5 on to a vibrating screen 6 along which it passes to a discharge trough 8. The fine coal and suspension liquid passing through the screen 7 and the suspension liquid passing through the screen 6 are led by a pipe 10 to near the bottom of a vessel 11, in which the water and fine coal tend to rise and overflow into a tank 16 while a dense suspension of sand is withdrawn from the bottom by a pump 14 and returned to the separating tank 3. Some of the fine coal and water in the tank 16 is discharged at an overflow 20 or through valve spigots 21, the rate of discharge being controlled to prevent accumulation of fine coal in the system. Additional water is supplied at any point of the system by a valved pipe 22, the remaining water and fine coal in the tank 16 being recirculated by the pump 18 to the bottom of the tank 3 where it helps to maintain the suspension, and to the screen sprays. A plurality of vessels 11, tanks 16, sand pumps 14, and water pumps 18 may be employed. Specification 119,038, [Class 82 (ii), Washing granular &c.], is referred to.