Abstract: A mill comprises a shaft mounted in a pair of bearings located at one end of the shaft, and a wall having an opening through which the shaft extends. A horizontal-flow container for the charge is removably mounted at one end in cantilever fashion upon one side of said wall and has a screened outlet at its other end. A tubular inlet housing is mounted on the other side of said wall, surrounding a portion of the shaft between said wall and said bearings, and has a seal through which the shaft enters the inlet housing. A feed screw is mounted on said portion of the shaft. Another portion of the shaft, extending within the container, is of greater diameter than said opening and is closely spaced from said wall to provide a narrow gap through which material passes from the inlet housing into the container. The shaft is hollow and has means for circulating a cooling fluid therethrough, and a shroud holds a cooling fluid in contact with the exterior of said seal.