Patent ID: 7503888

Claim:
An apparatus for separating intermixed particulate materials of different specific gravity in a slurry, comprising: a centrifuge bowl having a base and a peripheral wall surrounding an axis passing through the base and generally upstanding from the base to an open mouth; a mounting arrangement for rotating the bowl around the axis; a feed duct having a discharge mouth adjacent the base of the bowl for feeding the slurry into the bowl during rotation of the bowl so that, during rotation of the bowl, the intermixed particulate materials flow over the peripheral wall of the bowl from the base for collection of heavier particulate materials on the peripheral wall and for discharge of the lighter particulate materials in the slurry from the open mouth; a launder for collecting the lighter particulate materials in the slurry discharged from the open mouth; at least one annular recess on the peripheral wall over which the materials pass when fed from the supply duct as the materials pass to the open mouth for collection of the heavier materials in the recess; fluidizing openings in said at least one recess for fluidizing said heavier materials in said at least one annular recess; wherein the peripheral wall of the bowl includes a lead-in surface which extends axially of the peripheral wall from a lower end on the peripheral wall arranged for receiving said feed materials from the discharge mouth to an upper end of the lead-in surface at said at least one recess; said lead-in surface generally increasing in diameter from said lower end to said upper end so that the upper end is of greater diameter than the lower end; said at least one recess being located between the upper end of the lead-in surface and the mouth and extending generally radially outwardly relative to the axis from the upper end of the lead-in surface; the lead-in surface including a plurality of axially spaced surface portions each surrounding the axis with the portions being arranged in a row with each surface portion of the row being directly after the previous surface portion in the row in an axial direction from the lower end to the upper end; wherein each surface portion of the row is of smaller diameter than a subsequent portion of the row; and wherein each surface portion of the row has a trailing edge which connects directly to a leading edge of the subsequent surface portion of the row by an outwardly extending step; the surface portions are inclined outwardly and upwardly relative to cylindrical surface; the steps are substantially radial; the steps are inclined outwardly and upwardly to a radial plane at an angle greater than the portions.