Patent GB-457801-A (GB)
Title: Improvements in or relating to the pneumatic separation of materials of different specific gravities and sizes
IPC: B03B4/00
Filed: 1935-06-05
Abstract: 457,801. Separating solid materials. RIDLEY, F. F., and COLLIERY ENGINEERING, Ltd., 46, Rutland Park, Sheffield. June 5, 1935, No. 16398. [Class 117] Relates to apparatus for separating materials of different sizes and density by stratification on an air pervious support under the combined action of mechanical agitation and a current of air passing upwardly through the mass of material of the kind in which the heavier products settling to the bottom are progressively removed through discharge openings in the pervious support and the upper lighter layer traverses the whole length of the bed and is finally discharged at the end. According to the invention, the discharge openings are provided with a grating and lead into the air chamber so as to restrain the discharge of the heavy materials and at the same time maintain the zone above the openings, subject to the air current to avoid dead spaces. As applied to machines in which the support is constituted by a number of flat pervious sections arranged in series and connected by a solid inclined shoot as described in Specification 297,757, [Class 117], the openings are provided at the end of each section. Fig. 3 shows the end of one section a of the pervious support and the beginning of the next with the solid connecting shoot d. The discharge grating e is fixed at the end of the section and a masking plate m of the same mesh as the support a, may be pivotally mounted under each grating so as to be brought into position when it is desired to put one or more of the discharge openings out of action. To prevent disturbance of the bed as it descends the inclined shoot a small dam may be provided at the top edge of the slope or alternativelv a horizontal blade x and inclined blade x<1> may be provided for this purpose. The materials passing through the gratings are collected in one or a number of separate hoppers in the bottom of the air chamber, and are discharged outside the machine by air lock devices such as balanced valves. Fig. 2 shows in plan a machine having a series of separating zones A, B, C. The lighter material at the end of the zone C is diverted by a skimmer o into two discharge channels p<1> which may be solid or may be perforated to provide a further classification with the requisite discharge ports. The lower layer passing under the skimmer is received in a narrow channel p of pervious material for further treatment and by the aid of skimmers q, t the various grades of material are diverted to appropriate receptacles. The shoot s for the lighter material and the shoot r<1> for a middlings product are divided by a pivoted flap v so that the proportion of these products delivered to the shoots may be adjusted. The end shoot u for the heavy products that reach the tail end of the machine may be adjustable as described in Specification 274,587, [Class 117]. The invention is stated to be particularly applicable to the cleaning of coal in fine sizes and by the process described in Specification 274,587. The air-supply devices may be as described in Specifications 274,587, 297,757, and 305,068, [Class 117]. Two or more tables may be arranged as described in Specification 392,578.