Patent GB-531682-A (GB)
Title: Material classifier
IPC: B03B5/52
Filed: 1939-06-08
Abstract: 531,682. Wet-separating. HIRSCH, H. C. June 8, 1939, No. 16790. [Class 82 (ii)] A classifier for selectively separating suspended solid particles from a liquid, comprising a tank having an inclined bed and an end wall, liquid inlet means, a rotary screw conveyer for moving settled coarse particles upwardly along the inclined bed out of the liquid, to a discharge point, and outlet'means for discharging liquid and suspended fine particles from the tank, is characterized in that said outlet means comprises spaced vertical walls defining one or more vertical sorting columns and a weir or weirs for the overflow of liquid at the upper end of said column or columns, said walls being so arranged that all the liquid prior to being discharged from the tank flows vertically through said column or columns, the speed of the said flow determining the size of fine particles carried by the discharged liquid overflowing the weirs. The walls may be adjustable to vary the cross-sectional area of the sorting column or columns. The rotary screw conveyer comprises. a rotatable shaft with its lower end adjacent the tank end wall, helical ribbon flights mounted on but spaced from the shaft, and a bearing, sleeve rotatably supporting the lower end of the shaft and extending from. a point adjacent the tank end wall and lower than the liquid level in the tank upwardly through the space between the ribbon flights and the rotatable shaft to a point above the liquid level, means being so provided for preventing entrance of the liquid into the lower end of the bearing sleeve. In the form shown, suspension of solid particles enters a tank 10 by a launder 15 and is agitated by saddlewheel 68. Coarse particles which have fallen to the bottom of the tank are propelled upwards by the screw 20, driven by gears from motor 38, and discharged over weir 18. A suspension of fine particles discharges over a weir formed by a trapezoidshaped launder 45 secured in the bottom wall 11 of the tank by flange structure 43. Shaft 21 is held at the top by universal joint 27 and at the bottom by one or more bearings 49 in bearing sleeve 48 adjustably suspended on rod 51 in the block 50. The top end of the bearing sleeve is above the surface level and the bottom end is within the launder so that the bearings are kept free from the suspended particles. Braces 23 that support ribbon 25 are maintained' by spiders 22 so that part of the ribbon overreaches the shaft bearings. At the side of launder 45 are vertical baffles 55 preferably projecting from the surface and adjustable in inclination, and baffle 62 so that the suspension passes beneath the baffles, then upwards, and then overflows into the launder. Above the launder 45 may be placed a shield to prevent suspension from splashing into the launder. In a modification, the bottom of the bearing sleeve is sealed by a plate to prevent ingress of suspension and the plate is held by a cable so that the shaft inclination can be varied. The ribbons may be supported partly directly by spiders and partly bv braces that slope to a collar on the shaft. The width of the ribbon may vary preferably progressively from end to end.