FIELD: technological and geological studies and construction of mineral raw materials. SUBSTANCE: method of dry classification of powder material includes introduction of starting material into working chamber, disintegration of particles of starting material and forming flow of particles in working chamber by means of rotor with working members. Velocities of particles and gas flow in gas duct connecting the working chamber with first chamber of classifier are equalized due to use of barrier. Then, vertical gas flow is formed at gas duct outlet and starting material is classified in flow due to stepwise change of its velocity through stepwise increase of diameters of classifier chamber. Different fractions of classification are removed and conditions of classification are selected depending of starting material. Then, conditions for removal of heavy fraction from gas duct are created and this fraction is removed through opening found in gas duct wall. Conditions for removal of particles of heavy fraction from gas duct through opening in its wall are created as follows: barrier-reflector is placed in gas duct having elbow in way of flow of particles so that particles reflected from it should strike against gas duct walls, thus deceleration and changing direction of motion falling into hole in lower portion of gas duct elbow wall. EFFECT: increased productivity; improved quality of classification. 9 cl, 2 dwg, 3 ex
