GB1303067A - - Google Patents

Abstract

1303067 Upward current classifiers WILKINSON RUBBER LINATEX Ltd 16 June 1970 [16 June 1969] 30321/69 Heading B2H [Also in Division G3] A sorting column 1 for a hindered settling classifier, Fig. 1, is provided at its bottom with a discharge passage 8 in which is positioned a constrictible sleeve valve 9 for controlling the discharge of classified material through the passage. Water is introduced at 5 into a chamber 2 and flows through a perforated plate 3 upwardly through the column 1 so as to take finer or lighter particles of particulate material, fed in at 4, over a weir 6 to be discharged through an outlet 7. The coarser or heavier particles are discharged via the passage 8 and the valve 9. The density of the water/material mixture in the column 1 is sensed by means of a sensor 10 connected to a ball valve 13 in a hydraulic circuit which also includes a water tank 14, a pump 15, a constant flow valve 16 and the sleeve valve 9. The valve 9, Fig. 5, has outer casing with an intermediate bulbous portion 17 extending between end flanges 18. Extending internally between the flanges is a rubber sleeve 19 which in its free condition defines a cylindrical flow path 20 but which can be flattened to constrict the flow through the valve 9 by means of hydraulic pressure applied to the space between the portion 17 and the sleeve 19, the portion 17 being provided with tappings 22 to admit water under pressure from the circuit for this purpose. When the density of the mixture in the column 1 falls below a predetermined value, the valve 13 closes and hydraulic pressure in the circuit builds up causing constriction of the valve 9 thereby cutting off the flow of coarser material and water through the valve 9 and restoring the density to the predetermined value. When the density increases above the value, the ball valve 13 opens allowing the water to flow freely to waste so as to reduce pressure around the sleeve 19 which relaxes and permits passage of material and water at a greater rate. In a slightly modified arrangement, Fig. 2 (not shown), the sleeve valve 9 is connected to the hydraulic circuit by means of a branch pipe. In a modified control system, Fig. 3, the valve 13 is controlled by means of a float 25 movable in dependence upon the level of water within a header tank 26 which in turn is controlled by a sensor in the form of a probe 27 extending downwardly into the water in the column 1.