A tube mill is disclosed for grinding and drying granular material which comprises an elongated shell having one or more grinding chambers, and downstream of the first chamber, a dispersing compartment for receiving hot gases and material and bounded by a sieving diaphragm defining a central opening therethrough. A frustoconical sieve drum is attached to the sieving diaphragm for rotation therewith and forms a portion of an end wall of the discharge compartment.