PURPOSE: To efficiently gralunate a lamp of glass waste sand high in powder content and water content into small granules.

CONSTITUTION: A product taking out outlet 3 is formed in the lower side of the front half part and a raw material throwing inlet 5 is formed in the upper side of the rear half of a casing 1 formed into almost a cylindrical shape and a cylindrical screen 2 is installed in the inside of the front half part. A large number of arm rods 7, 7 are reciprocally projected in the front half part of a rotary shaft 6 set transversely in the inside of the casing 1 and stirring blades 8, 8 are attached to the tip parts of them. In the rear half part of the rotary shaft 6, double spiral type screw 9 in which two screw blades 10a, 10b are installed wherein the phases of the blades 10a, 10b are differed from each other and the blades have a recessed and a projected parts 11, 12 formed reciprocally at their tip parts is installed. The thrown-in raw material is sent to a gap between the screw' s blades and the casing 1 by the double spiral screw 9 without being compacted and forming layers and pulverized and shifted by the stirring blades 8, 8 and the cylindrical screen 2.