A vertical spindle pulveriser including a housing structure in which a spindle, having a grinding disc attached near one end thereof, is vertically and rotatably mounted. A complementary grinding disc is fixed in the structure above the first disc, a compartment is formed in the structure about and below the discs, a receptacle is located below the discs and a feed hopper is provided such that is communicates with a space between the discs. Provision is made for improved means for supplying air under pressure to automatically sweep the interior of the pulverizer and these means include an axial central bore through the spindle, at least one radial outlet through the spindle which emerges facing the upper fixed grinding disc and at least one radial outlet through the lower end of the spindle below the discs. Other air outlets are provided in the pulverizer for cleaning other parts thereof, and these outlets and the axial bore in the spindle are connected to a source of compressed air through a control valve which is automatically activated when the receptacle is removed after a comminuting operation.
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