Abstract: An apparatus and method for removing debris from granular material, utilizes a pair of inner and outer ducts, which are separated by an air chamber for guiding and discharging a backward flow of air under pressure through a passageway opening extending between the two ducts. The air pressure flows through flowing granular material as it moves along a given path from the first duct into the second duct. A spreader member guides the flow of material into an opening between the edge of the spreader and the wall of the outer duct. A porous member disposed downstream of the spreader member near the opening receives the material flowing through the opening and is inclined from the wall toward the central axis of the outer duct, as the air flows backwardly through the porous member.