Patent GB-1209624-A (GB)
Title: Improvements in or relating to density separation apparatus
IPC: B03B5/16
Filed: 1967-11-02
Abstract: 1,209,624. Jigging apparatus. BUREAU DE RECHERCHES GEOLOGIQUES ET MINIERES. 2 Nov., 1967 [10 Nov., 1966], No. 49926/67. Heading B2H. A jig for separating particles according to density comprises a liquid-containing tank, a diaphragm constituting the bottom of the tank and adapted for reciprocating vertical move ment, and a grid spaced vertically above the diaphragm for carrying particles to be separated, the diaphragm being so arranged that the amplitude of its reciprocating motion is much stronger at one central zone than at other zones on its surface, whereby in operation the reciprocating liquid is displaced through the grid and the motion of the liquid includes a horizontal component so that concentration of the heavier particles is effected on the grid in a zone corresponding in vertical alignment to the central zone of the diagram. In Fig. 1, a grid 1 having larger apertures in its centre portion 14 is clamped between parts 2, 3 of a tank, the bottom of which is constituted by a frusto-conical, reinforced, flexible diaphragm 6 which is provided with a central opening communicating with a preferably transparent tube 8 for the discharge of the heavy particles. The diaphragm is reciprocated by means of a lever 9 connected at one end to the tube 8 and pivotable at 10. The other end of the lever 9 may carry a displaceable sleeve on which is mounted a roller, Fig. 13 (not shown), which cooperates with a motor-driven cam for actuating the lever, the feet of the upright 5 on which the tank is supported being guided in slides so as to vary the stroke of the diaphragm. The conical form adopted by the diaphragm in the course of its alternating motion gives a maximum impulse to the liquid in the centre and none at the periphery. A jigging action is obtained having a horizontal component which is directed towards the axis of the apparatus resulting in a concentration of the heavier particles towards the centre portion 14 of the grid where they are removed through the larger apertures. The modifications of Fig. 1: (a) the grid is mounted in the bottom of a removable cylindrical member which is partially inserted in the tank and has flanges resting on the top edge of the tank; (b) the cylindrical member with the grid is inserted completely in the tank and rests on an annular, inwardly directed flange therein; (c) the last arrangement is modified by having a diaphragm with no opening in its centre; (d) an annular baffle may be mounted on the wall of the tank below the grid in any of the preceding constructions in order to increase the concentration of the heavy particles in the centre portion of the grid; (e) modified constructions for connecting the discharge tube 8 to the actuating lever 9 are described, Figs. 7 to to 9 (not shown). In Fig. 6, separation is improved by providing above the grid 33 a filter bed consisting of. grains of larger dimension than the dimension of the largest apertures in the grid. The Figs. 10 and 11, a portable jig has a filter bed 63 on top of a grid 64. A rotatable impeller 60 is provided above the bed for uniformly distributing products to be separated or for removing separated particles from the bed. During transport, a cover 62 is provided above the bed. The impeller 60 is then insulated above a spring 66 which exerts pressure on the cover 62 and keeps the bed in position. The lever 54 is withdrawn from its normal dotted position and inserted in a sleeve 55 carried by the impeller.