GB1037279A - Improvements relating to the dry-cleaning of large or small coal, or other particulate materials containing components of different specific gravities - Google Patents

Abstract

1,037,279. Pneumatic separators. HEAD, WRIGHTSON & CO. Ltd. April 12,1965 [April 30, 1964], No. 18060/64. Heading B2H. An apparatus using a fluidized bed of particles for cleaning coal or another particulate material containing components of different densities comprises a vibratory horizontal or inclined trough 1, at least two air or gas chambers separated by a transverse partition 5 beneath a gaspervious support 6 of which the first chamber is located beneath a cleaning zone alpha and the second beneath a discharge zone b, extractor means 14 for removing the light fraction from the surface of the fluidized bed, vibrating means 13 for moving at least the heavy fraction towards a discharge outlet and means 100 for adjusting the supply of air or gas to the discharge zone, the rate of discharge of the heavy fraction being dependent upon the vibration of the trough and the degree of fluidity in the discharge zone. As shown, one longitudinal and four transverse partitions 7 divide both the first air or gas chamber into five pairs of smaller chambers 3a-3e and the second into one pair of smaller chambers 4alpha, each being supplied independently with air or gas through a valve 100 which regulates the density of the fluidized bed. The trough 1 may be supported from the floor or suspended as shown by straps 2 and vibrated by a motor 13 having out-of-balance weights; in alternative arrangements, the vibrations may be produced by a magnetic vibrator or a crank and connecting rod. Magnetite particles for the fluidized bed are continuously fed into the trough at 11 from a hopper 19 and raw coal is introduced at 12. The extraction means for the floating light material may be in the form of a stationary splitter plate or, as shown, a conveyer 14 which serves to carry the light fraction to where it can be discharged into a "cleaned coal" compartment of a collecting vessel 15. The heavy fraction sinks and is discharged into a "discard" compartment. In a modificiation, the extraction means 14 is in the form of a porous plate 201, Fig. 9 (not shown) mounted in a horizontal or inclined position on a wedge-shaped. air or gas chamber for fluidizing the material as it is discharged. The collecting vessel 15 serves to size the material and pass the undersize particles consisting of magnetite and finely-divided coal and discard for recirculation to the hopper 19, a magnetic separator 16 treating a portion of the recirculated material and discharging the non- magnetic fraction at 17; make-up magnetite is fed into the hopper at 20. If desired, the raw coal may be separated into three fractions according to density by first passing the material along one side of the trough which is divided longitudinally above the support 6 by a partition 21, Figs. 3, 4 and 5 (not shown), and then passing one of the two separated fractions along the opposite side of the trough for separating out the third fraction which may be the "middlings", the density of the fluidized bed on each side of the partition being controlled by the valves 100. The supply of air or gas to the cleaning and discharge zones a, b may be separate and if desired pulsated. The material being treated may be dried, if necessary, by either pre-heating the air or gas or the magnetite supply or heating the magnetite in the first portion of the trough, the heating being carried out directly or indirectly by use of hot gases or heating coils. Instead of magnetite, the fluidized bed may be composed of particles of ferro-silicon, sand or a mixture of magnetite and sand. In another embodiment, Figs. 6, 7 and 8 (not shown), the apparatus is T-shaped in plan view, the cleaning zone being constituted by the bar of the T and the discharge zone by the leg. Raw coal and magnetite are fed into one end of the cleaning zone. The floats are swept over an inclined perforated plate 22 and out of the apparatus at the opposite end by a paddle conveyer 121 while the sinks are led by a sloping porous bottom 6 through a central aperture into the discharge zone, the aperture being partly shielded by a perforated plate 23.