Patent GB-1327039-A (GB)
Title: Treatment of materials for the separation therefrom of fractions of different density
IPC: B03B5/08
Filed: 1969-12-05
Abstract: 1327039 Washing granular materials NATIONAL RESEARCH DEVELOPMENT CORP 2 Dec 1970 [5 Dec 1969 11 March 1970 (2)] 59664/69 11692/70 and 11693/70 Heading B2H Ores or other solid materials are separated into fractions of different density by feeding the material to the surface of a conveyor which conveys it upwardly against a downward flow of wash liquid, imparting to the surface a first orbital shaking motion to facilitate an initial separation of the fractions and a second orbital motion of lower frequency and/or higher amplitude than the first to facilitate discharge of the lighter fractions from the surface, and discharging the heavier fractions from the upper end of the surface and the lighter fractions from the lower end of the surface. In the apparatus shown in Figs. 1 to 3, the conveyor is an inclined belt 1 of reinforced plastics passing around a vertically adjustable idler pulley 2 and a driving pulley 3 mounted on a sub-frame 4. Downstream of the feed zone the belt is supported to provide a flat surface by rods 6 attached to the sub-frame and, in the feed zone in order to provide a surface of shallow V-cross section it rests upon pairs of transverse rods 10 pivotable near one end at 11 and attached at the other end to the sub-frame. Troughs 14, 15 on the subframe serve to collect the heavier and lighter fractions respectively. A scraper 17 contacts the lower surface of the belt 1. The sub-frame 4 is suspended from a fixed frame 18 by wires 20 of adjustable length. A variable speed electric motor 22 attached to the sub-frame drives through belt and pulleys a shaft 25 which in turn similarly drives the drive roller 3 through a gear box 31. The motor 22 also drives through pulleys of different diameters and belts two shafts 32, 33 mounted on the sub-frame 4 beneath the belt and provided with shake-arms 38, 39 on which are adjustably mounted shake-weights 40, 41 providing respectively the first and second orbital motions, the mass of the weight 40 being half that of the weight 41. Feed boxes 42 mounted on opposite sides of the fixed frame 18 to feed material on to the surface 9 of the belt comprise a container portion 43 into which a liquid suspension of the material to be separated is fed through tubing 44 at a rate controlled by a valve 45, and from which the suspension overflows into longitudinal channel portions formed in the feed boxes and arranged at narrow angle to the longitudinal axis of the belt. Wash water is supplied through flexible tubes 50, 51 at a rate determined by a valve 52 to tubes 48, 49 vertically adjustable above the belt and formed with holes in their upper surfaces, wire drip points 57 being provided at each of the holes so that the wash liquid falls on to the surface of the conveyor in dropwise fashion. In alternative constructions, the orbital shaking motions may be provided by cranked shaking shafts. The shaft providing the second orbital motion may be mounted outside the framework beyond the end away from which the material is conveyed by the conveyor surface. The wash liquid may be supplied at positions spaced along a line parallel to the direction of conveyance of the material. It may again be supplied to the feed zone by a pair of passages at either side of the conveyor. The material may be fed to the conveyor in the dry state. Alternatively, the material may be fed in suspension in a liquid in end-flow or cross-flow fashion.