Abstract: There is disclosed a self-attritioning pulverizer incorporating a cylindrical shell having a reduced-in-diameter, cylindrical sizing screen assembly telescoped concentrically thereinto and separated therefrom by an annular collection chamber. Mounted on the interior of such screen assembly are a plurality of equally spaced, axially extending radial holding baffles terminating at their radially inner sides in blunt edges cooperating together to form the radial interior of an annular holding chamber. A four bladed cruciform impeller is rotatably mounted from one end wall of such cylinder in coaxial relationship with such cylindrical shell with the radially outer extremities of such blades terminating in blunt edges spaced, as such impeller is rotated past such baffles, a radial distance from the edges of such baffles at least as great as the minimum cross-sectional dimension of unreduced chunks to be pulverized thereby.