Patent ID: 8353408

Claim:
A centrifugal air classifier comprising: a rotor provided in a casing and including a dispersion plate and a rotational plate, the plates being fixed to a rotor rotational shaft with a space therebetween in an axial direction, and a plurality of rotor blades held between outer circumferential parts of the both plates; guide vanes provided outside the rotor blades so as to be opposed to the rotor blades through a classification space; an air inlet provided in the casing for supplying the classification space with air for classification through the guide vanes; a powder inlet provided in an upper part of the casing so as to be faced to the dispersion plate; and a fine powder outlet for discharging a classified fine powder to an outside of the classifier; wherein a relation between an area S 1 of a side surface of a cylinder or a truncated cone circumscribed about the rotor blades, an axis of the cylinder or the truncated cone being the rotor rotational shaft, and a calculation average value D of a diameter of a circle orthogonal to the rotor rotational shaft and circumscribed about the rotor blades is S 1 /D 2 =0.9 to 1.6.