GB391240A - Improvements in classifiers - Google Patents

Abstract

391,240. Gravity separation apparatus. DORR CO., Inc., 247, Park Avenue, New York, U.S.A. Nov. 18, 1931, No. 31962. Convention date, Nov. 18, 1930. [Class 46.] A bowl classifier comprises a settling chamber of varying depth having a plurality of scrapers rigidly connected to an arm or sweep positioned above the liquid level, the scrapers having their upper edges in a horizontal plane and varying in height with the depth of the chamber. In the form shown a flat conical bowl 1 having an opening 3 at its lowest point is mounted above a secondary classifier 2 of known type containing a reciprocating rake 5, an upward current being produced through the opening 3 by the introduction of liquid into the secondary classifier 2 through an inlet pipe 45. A motor 15 on a framework 14 mounted above the bowl 1 drives a vertical shaft 16 carrying radial arms 17 which are positioned above the liquid level in the bowl and are connected to scrapers 18 by brackets 19 preferably of I-beam construction so that the edges of the brackets cut the surface as the arms revolve and produce a slight surface agitation. The scrapers 18 have their upper edges in a horizontal plane below the liquid level and increase in height from the periphery of the bowl to the centre, the bottom edges lying adjacent the bottom of the bowl. The material to be treated is supplied in suspension to an annular feed well 24 through a tangentially disposed inlet pipe 23 and passes through perforations 25 in the bottom of the well on to a circular distributing plate 26 mounted on the upper edges of the radial arms 17. The distributing plate 26 is joined by a wall 28 to an apron 29 having a weir 30 spaced from its edge, a baffle ring 32 being provided to direct the suspension into the annular space between the wall 28 and the weir 30, from which it overflows the weir 30 and flows radially over the edge of the apron intc the bowl. The apron 29 is positioned slightly below the fluid level in the bowl. The lighter particles flow over an adjustable weir 20, formed by a rubber band secured round the upper edge of the bowl, into a circular launder 21. The heavier particles settle and are carried by the scrapers to the outlet 3, whence they pass intc the chamber 2 and are removed by the rake 5. The outlet 3 is provided with gates 34 sliding in guides 33, Fig. 4, so that the size of the opening may be adjusted. The position of the scrapers may be adjusted by raising or lowering the shaft 16 by means of a wheel nut 46