A rotary feeder for feeding a particulate material comprising: a) a cylindrical housing (102, 202) comprising a feeder inlet (104, 204), a first feeder outlet (106, 206), and a second feeder outlet (108, 220); b) a rotor (110, 208) mounted in the cylindrical housing(102, 202) comprising a plurality of impeller blades (112, 212) defining a plurality of circumferentially spaced pockets (114, 214) alignable with the feeder inlet (104, 204), first feeder outlet (106, 206), and second feeder outlet (108, 220), and adapted to sweep a wall (116, 216) of the cylindrical housing (102, 202) as the rotor (110, 208) rotates in the cylindrical housing (102, 202); c) a device for rotating the rotor (110, 208); and d) a separating screen (118, 222) in the first feeder outlet (106, 206) to substantially prevent oversize material from exiting through the first feeder outlet (106, 206), wherein each of the plurality of circumferentially spaced pockets (114, 214) are made to align with the feeder inlet (104, 204) to receive therein a particulate material and an oversize material through the feeder inlet (104, 204), rotate in the cylindrical housing (102, 202) to align with the first feeder outlet (106, 206) and discharge the particulate material therefrom, and rotate in the cylindrical housing (102, 202) to align with the second feeder outlet (108, 220) after alignment with the first feeder outlet (106, 206) and discharge the oversized material therefrom, characterized in that the separating screen (118,222) comprises a bar grate, the bar grate comprising either a series of parallel bars aligned in the same direction as the rotor rotates, the parallel bars comprising at least one of nodules and serrations on an upper surface thereof, or bars aligned transverse to the direction of rotor rotation. a) a cylindrical housing (102, 202) comprising a feeder inlet (104, 204), a first feeder outlet (106, 206), and a second feeder outlet (108, 220); b) a rotor (110, 208) mounted in the cylindrical housing(102, 202) comprising a plurality of impeller blades (112, 212) defining a plurality of circumferentially spaced pockets (114, 214) alignable with the feeder inlet (104, 204), first feeder outlet (106, 206), and second feeder outlet (108, 220), and adapted to sweep a wall (116, 216) of the cylindrical housing (102, 202) as the rotor (110, 208) rotates in the cylindrical housing (102, 202); c) a device for rotating the rotor (110, 208); and d) a separating screen (118, 222) in the first feeder outlet (106, 206) to substantially prevent oversize material from exiting through the first feeder outlet (106, 206), wherein each of the plurality of circumferentially spaced pockets (114, 214) are made to align with the feeder inlet (104, 204) to receive therein a particulate material and an oversize material through the feeder inlet (104, 204), rotate in the cylindrical housing (102, 202) to align with the first feeder outlet (106, 206) and discharge the particulate material therefrom, and rotate in the cylindrical housing (102, 202) to align with the second feeder outlet (108, 220) after alignment with the first feeder outlet (106, 206) and discharge the oversized material therefrom, characterized in that the separating screen (118,222) comprises a bar grate, the bar grate comprising either a series of parallel bars aligned in the same direction as the rotor rotates, the parallel bars comprising at least one of nodules and serrations on an upper surface thereof, or bars aligned transverse to the direction of rotor rotation.