The present invention a material classifier includes a cyclone including a cyclone inlet, a cyclone outlet, a blower and a blower discharge; an air diffuser connected at a diffuser inlet to the cyclone outlet and at a diffuser outlet to an air lock such that the cyclone and air diffuser are in fluid communication; wherein the diffuser including a central cylindrical portion including an air inlet for admitting controlled amounts of diffuser air around substantially the entire cylinder outer periphery of the central cylindrical portion, wherein the material classifier separating fine particles from coarse particles and discharging the fine particles together with air out the blower discharge, and discharging the coarse particles through the air lock, such that varying the amount of diffuser air one can control the size of the fine particles being separated from the coarse particles.