Patent GB-970643-A (GB)
Title: Improvements relating to the drying and cleaning of small or fine coal, or other particulate materials containing components of different specific gravities
Inventor: EVESON GEOFFREY FRANK
IPC: B03B4/06
Filed: 1961-01-03
Abstract: 970,643. Drying coal &c. HEAD, WRIGHTSON & CO. Ltd. Feb. 21, 1962 [Jan. 3, 1961], No. 240/61. Heading F4G. [Also in Division B2] In an apparatus for drying and separating components of differing specific gravities, e.g. of coal &c., the coal is introduced into a vessel 10, Fig. 1, at 11 and fluidized in a bed a by a hot gaseous medium so that the bed is partially or wholly dried and the fines are carried off at 12 in the gas, the heavier coal passing via an overflow pipe 8 to a fluidized bed b of magnetite or other discrete solid particles, e.g. sand, which are introduced at 13 into the vessel so as to further dry and separate the components for removal, the fraction of lower S.G. arising from the coal being withdrawn continuously together with some magnetite at 14 and the fraction of higher S.G. sinking through the fluidized bed b for discharge through a down-pipe 9. Fluidization of the beds a, b is effected by hot gas introduced into the vessel at 6 and 3 respectively. Discharge of the magnetite with the coal through the pipe 9 is partially controlled by the introduction thereinto of gas at 4 to separate the mixture in an elutriation process wherein the gas is introduced at a controlled rate sufficient to maintain the interstitial spaces of the pipe 9 substantially free from magnetite passing into the pipe with the higher S.G. separated coal. A rising tube 16 having a skirt-type baffle may be mounted in the bed b above the pipe to collect gases admitted at 4 together with eluted magnetite and small particles of higher S.G. coal, and gases admitted at 5 inside the tube ensure the S.G. of the suspension of particles within the tube is less than that of the bed b so that a perforated hood and screen 17 allows the gases and much of the magnetite to pass therethrough whilst the small particles of higher S.G. and the remainder of the magnetite are retained to leave the vessel at 18. In operation, the coal fed to the fluidizing vessel 10 is partially or completely dried and de-dusted in the bed a and continuously discharged at 8 into the fluidized bed b of magnetite and separated at controlled S.G. into a clean coal fraction A discharged at 15, and a reject fraction B discharged at 7, each fraction passing through vibratory screen-type sizing devices 21, 22 from which the majority of the magnetite passes to dry-type magnetic separators 23, 24, a single demagnetizer 25, a heater 26 and back to the vessel 10 at 13, and the small non-magnetic particles leave the separators 23, 24 at 27 to join the larger products at 28. Fines are carried from the vessel 10 in the hot gas stream 12 for separation in a cyclone 29 to join products A, B or introduced at E as fuel to a furnace 31. The gases from the cyclone 29 pass through dry dust collectors 32 for removal at 33 as fuel and then divide in controlled amounts either to join hot gases from the furnace at 35 or to be vented to atmosphere and the gases from the furnace divide to flow as stream 37 to enter the vessel 10 at 3, as stream 38 to enter the vessel at 6 or as stream 39 to the heater 26.