Patent GB-1072233-A (GB)
Title: Methods and apparatus for density separation of particulate material
Inventor: LANE HENRY ROBERT ARTHUR
IPC: B03B4/00
Filed: 1962-12-17
Abstract: 1,072,233. Pneumatic separation. COAL INDUSTRY (PATENTS) Ltd. Dec. 6, 1963 [Dec. 7, 1962 (6)], Nos. 46273/62; 46274/62; 46275/62; 46276/62; 56277/62 and 46278/62. Heading B2H. In a process for separating particulate materials, e.g. coal from shale, a fluidised bed of dense medium is established in a vessel, trough or launder by means of a flow of gas which is introduced through a previous base of the vessel &c., to pass through the dense medium in the vessel &c., and the particulate material is introduced in the vessel &c., so as to be separated into two or more superposed fractions differing in density, the vessel &c., being vibrated so as to cause the particulate material to travel from a predetermined feed location to at least one delivery location at which the separated fractions are removed from the vessel &c. In Fig. 1 raw coal and dense mediumare fed together or separately at 34 to an inclined trough 33 having a gas pervious base 11 through which gas passes from a box 13. Refuse and some dense medium pass along a plate 36 at the discharge end 35 while clean coal and some dense medium are removed over a plate 37. In Fig. 2, refuse and dense medium are taken off at various points along the trough through exits 38 in the base or side of the trough. Clean coal and some dense medium are discharged over a plate 39. In each of the above embodiments, vibration of the trough may be effected by mounting it on to resilient supports, e.g. springs (19), Fig. 3 (not shown), and imparting a vertical reciprocatory motion to the assembly by means of an eccentric (20) and links (21) driven by an electric motor (22). Pulsations may be produced in the fluidised bed by pulsing the gas supplied to the box (13), Fig. 4 (not shown), by passing it through a control valve (12) in a feed conduit (12A), or by feeding a pulsating air supply into the bed (10), Fig. 5 (not shown), via a distributor box (16) by means of an oscillating diaphragm (15), the air being supplied to the box (13) at constant pressure. In order to alter the path in the bed of the smaller size ranges of particulate material, a horizontal component of velocity may be imparted to the fluidising gas during its passage through the bed. This may be accomplished by supplying a cross flow of medium in the vessel through a side pipe (32), Fig. 6 (not shown), in order to distribute fluidised medium across the width of the bed, by creating a vortex in the vessel or by mechanical agitation of the fluidised bed. As an alternative arrangement for extracting the refuse the outlet end of the apparatus of Fig. 1 may be provided with a reject compartment (25), Fig. 7 (not shown), which communicates with the main compartment (24) of the trough. In operation, the refuse sinks to the bottom of compartment (24) and due to the pulsations rises in the compartment (25) to be discharged over a weir (27) which may be equipped with a paddle. In the above embodiments, the gas-pervious base 11 may be formed from porous ceramic tile, asbestos belting containing Terylene (Trade Mark) weaves, or stainless steel mesh. Alternatively, the base may be constituted by a graded bed of granular solids of varying size range. The dense medium for the fluidised bed may be formed by superposed layers of media of different densities, e.g. magnetite and powdered iron. Moisture may be removed from the feed material by heating the fluidising gas or the dense medium. A number of vessels or troughs may be arranged in series.