GB340242A - Improvements in or relating to the classification or separation of mixed materials by elutriation - Google Patents

Abstract

340,242. Classifying and settling apparatus. ANDREWS, L., 11, Southampton Row, London. Sept. 19, 1929, No. 28434. [Class 82 (ii).] In connection with a classifying tank having one or more settling hoppers an underflow pipe of comparatively small bore is provided, communicating with the lower ends of the hoppers and through which liquid from the same source as that supplied to the classifier is passed at a high velocity. Means are provided for varying the relative proportion of the liquid passing through the classifier and the underflow pipe and for controlling the rate of flow through the outlet end of the underflow pipe, so that liquid may be caused to pass upward through the hoppers to remove finer material mixed with the heavier deposits therein or the heavier deposits may be discharged from the hoppers through the underflow pipe. Mixed material under treatment is received in a supply receptacle i, Fig. 1, and part passes thence through a pipe d and inverted cone d<x> into a classifier a and part through an underflow pipe c connected to the funnel-shaped lower portion of the receptacle i and through valves s with hoppers a<1> of the classifier. A valve d<1> controls the flow through the pipe d and thus the liquid level in the vessel i, and the relative amounts of liquid discharged through the pipes d, c. The outlet end of the pipe c is fitted with a valve c<2> and may be of reduced bore. It is connected to a supplementary classifier o, which may be of the kind described in Specification 340,027. The heavier deposits drawn from the hoppers a<1> separate in the classifier o and are discharged through an outlet o<1>. The finer material is carried by the liquid through a siphon r which discharges into a duct h into which the liquid and finer material from the classifier a is discharged through a pipe g. In modified apparatus shown in Fig. 2 the matter deposited in a supplementary classifier u is withdrawn by a pump 2 operated by an electric motor 10. A trickle of water is supplied to a tank 4 through a pipe 5 and water passes from the tank 4 to the vessel u through a pipe 3. An alteration of density in the vessel u causes the water level in the tank 4 and a float 6 therein to rise or fall, the movement being communicated by levers 7, 8 to a resistance device 9 in the circuit of the motor 10. The working of the pump 2 is thus regulated so as to maintain a constant density around the lower end of the pipe 3. Lighter matter passes from the vessel u through a pipe w to the inlet end of the classifier a.