Abstract: Particle classifier (2) for separating solid particles in a flow of gas and particles (1) into two fractions depending on size by means of gravitation force, air resistance force and applied centripetal force. A mixture of gas and particles is charged well dispersed to a classifier inlet zone (3) from which the mixture is brought into contact with a rotor (6) in a first separation zone (5) having the form of a free rotor chamber. Gas and fine particles are allowed to escape through an upper outlet (9) while the coarse fraction of the particles is forced to pass through a second separation zone and subsequently to leave through a lower outlet (15).