GB657090A - Improvements in or relating to a process of separating solid granular materials having different densities - Google Patents

Abstract

657,090. Washing granular materials. TROMP, K. F. Oct. 7, 1947, No. 26905. [A Specification was laid open to inspection under Sect. 91 of the Acts, Dec. 13, 1948.] [Class 82(ii)] In a process of separating granular materials having different densities by means of a stream of liquid medium of intermediate density, the floats as well as the sinks are removed by mechanical means moving in the same direction as the liquid medium and the liquid medium flows underneath the discharge shoot of the floats and over the weir over which the sinks, are removed. An apparatus for carrying out this process comprises a tank 1 containing a liquid medium 2 which is fed from conduits 13, 14, 15, 16 and discharged over a weir 1b into a transverse trough 18. The material to be separated is charged by a shoot 17, the floats being swept up a perforated chute 4 by a conveyer 3, and the sinks removed by a drag conveyer 8, the working faces of both conveyers moving in the same direction as the liquid stream. The ratio of the speeds of conveyers 3 and 8 is equal to the ratio of the volumes of floats and sinks in the material and the feed of liquid per second by the inlet 9 is equal to the amount of liquid per second drawn by conveyer 3 if there were no floats. The conveyers comprise endless chains interconnected by scrapers of suitable size or in a form (not shown) the conveyer 8 is replaced by an imperforate belt in which the driving roller of the belt forms the weir. In another form. of apparatus (not shown) the chute 4 is not perforated and does not extend to the weir 1b and the liquid is kept flowing at a constant velocity by a second conveyer. The velocity of the liquid may be kept constant by discharging some of the liquid through a sieve into a conduit or by means of the arrangement in Fig. 6. In this arrangement a rod 25 carries an arm 26 at each end, the other ends of the rods being connected by a rod 27 carried in bearings. Secured to the rod 27 is an impeller 28 and carried at each end of the rod are a disc 32 and a crank 29 hinged to a rod 30 which is attached to the corresponding arm 26 by a spring 31. The arms 26 are swung about the rod 25 by a connecting rod 36 attached to a crank 37 rotated by external means. Radially the cam 32a of the, disc 32 is engaged by a spring loaded pawl 33 and as the arm 26 moves, the disc 32 together with the impeller 28 are rotated until stopped by an'abutment 35, the impeller then being parallel to the arm. At the end of the arm's motion another cam 32b of the disc 32 engages with a stop 39, attached to the tank wall, and the impeller is rotated until it is at right angles to the arm so that the liquid is undisturbed on the return stroke.