Methods and apparatus for classifying fine particle solids

Abstract

A method and apparatus are provided for classifying fine particle materials from a fluid suspension in the form of a rotatable cylindrical bowl, a rotatable shaft on which said bowl is rotated, means for independently rotating each of said bowl and shaft at appropriate differential speeds, a circular baffle on said shaft within said bowl between the ends of said bowl, defining one, of three, consecutive pools, a helical conveyor on said shaft on one side of said baffle in said one pool, said conveyor extending radially to a point adjacent the periphery of the bowl, a second pool beginning on the opposite side of said baffle and extending toward the effluent end of the bowl, a helical series of discontinuous radial spokes extending from said shaft in said second pool, and extending to points adjacent the periphery of the bowl, said second pool ending at a point where it joins a third pool of equal cross sectional dimension and extending toward the effluent end of the bowl, a ribbon-conveyor mounted on said shaft in said third pool whose outer periphery closely approaches the inner periphery of the bowl, an input port delivering slip to be centrifuged to the helical conveyor at one end of the bowl, a particle reject port at the same end of the bowl as the input port and a slip discharge port at the opposite end of said bowl spaced from its periphery.