Abstract: A ball tube mill has a housing with an inlet and an outlet for material to be comminuted accommodates annular wall plates spaced at a predetermined distance from each other, arranged at an angle to the longitudinal axis of the housing, and having the form of an ellipse. The space between the adjacent annular wall plates is somewhat greater than D/tan .alpha., where D is the inside diameter of the housing, and .alpha. is the inclination angle of the annular wall plate to the longitudinal axis of the housing.

Abstract: A ball tube mill includes a rotatable housing with a lined inside surface and end cover plates having an inlet hole and an outlet hole and accommodating at an angle to its longitudinal axis at least one perforated wall dividing the housing into coarse and fine grinding chambers charged with grinding bodies. The lined inside surface of the chambers has the form of truncated cones facing by their large bases the perforated wall, the angle of inclination of a generating line of the truncated cones equalling the angle of the slope of the grinding bodies present in the respective chamber, the volume of the coarse grinding chamber being smaller than the volume of the fine grinding chamber.