Image Number 2 for United States Patent #5725102.
In a method for separating heavy particles from a particulate material containing such heavy particles, use is made of a device having a Coanda sifter, which is adapted to receive a flow of the particulate material and which has a downwardly-facing, convexly single-curved surface (9), and a zigzag sifter (13) arranged after the Coanda sifter and having a plurality of zig-zag-shaped vertical walls (14) which are perpendicular to the axis of curvature of the single-curved surface (9) and define between them channels (15) extending upwards in zig-zag fashion. The particulate material is transported to the Coanda sifter and is conducted over its convexly single-curved surface (9) to have imparted to it a direction of motion (P1, P2) which is dependent on the weight of the particles and in which the particles are guided into the zigzag sifter (13). The particles are guided into the channels (15) of the zigzag sifter (13) in the lower portions thereof and from the side parallel to the channel walls (14). The particles are transported up through the channels (15) with the aid of a flow of transport air which is so adjusted that the heavy particles are separated in the zigzag sifter. (13).