B2 abstract apparatus for removing debris from a fluidized sand bed one or more troughs extend radially from a vertical shaft associated with each trough is a perforated chute the apparatus is placed into the fluidized bed of sand and rotated as the apparatus rotates the perforated chute sifts or separates debris from the fluidized sand that is the fluidized sand flows through the perforations but the debris does not when the apparatus is removed from the fluidized bed the debris tumbles down the chute into the troughs if it has not already done so and is captured application_number US 90237601 A description fig5 illustrates one form of the invention and the structure shown in fig5 will be explained by reference to fig3 and 4 fig3 illustrates a helical screen 30 which is supported by a shaft 32 fig4 illustrates walls or dams 34 which are placed onto the helical screen 30 the walls 34 extend radially from shaft 32 fig5 illustrates a helical outer wall 36 which is attached to the outer edge of the screen 30 and the overall structure forms an auger 38 the mechanisms by which the auger 38 operates will first be explained by an analogy to a two dimensional inclined ramp for simplicity fig6 illustrates the ramp 40 which is inclined as indicated by angle 42 which ramp 40 makes with the horizontal represented by plane 44 a screen 46 forms the bottom or deck of the ramp 40 and corresponds to screen 30 in fig3 5 the screen 46 of fig6 is also shown in fig7 which is a cross sectional view taken at plane 47 in fig6 as viewed by eye 51 upstanding barriers 53 serve to catch debris in a manner to be later described and correspond.