Patent ID: 8430246

Claim:
An apparatus ( 100 ) for sifting feedstock ( 1 ), comprising a. a static sifter ( 2 ) having an aeration base ( 4 ) which is oriented at an angle to the vertical and through which sifting gas ( 3 ) flows, b. an inlet opening ( 9 ) for feeding the feedstock ( 1 ) onto the aeration base ( 4 ), c. an outlet opening ( 10 ) for the coarse material, d. a dynamic sifter ( 5 ) which is arranged downstream and which comprises at least one rotor ( 6 ) having rotor blades ( 15 ) and a horizontal rotor axis, e. at least one outlet opening ( 11 ) for the sifting gas charged with fine material, f. and also a housing ( 8 ) in which the static and the dynamic sifter are arranged, the region of the housing surrounding the dynamic sifter ( 5 ) being in the form of a housing volute so that a substantially tangential flow of sifting gas against the rotor ( 6 ) results, characterised in that the rotor blades ( 15 ) are set an angle (α) of from 10 to 50° relative to a radial direction ( 16 ) of the rotor, the rotor blades being offset at their outer circumference relative to a radial orientation in the direction of rotation of the rotor, and the direction of rotation ( 14 ) of the rotor ( 6 ) is counter to the direction of flow of the sifting gas ( 3 ) in the housing volute.