GB535035A - Improvements in or relating to combinations of wind-swept grinding or pulverising mills with classifiers - Google Patents

Abstract

535,035. Ball &c. grinding mills. NEWELL & CO., Ltd., E., and HOWDEN, P. Nov. 8, 1939, No. 29624. [Class 59] In combinations of wind-swept grinding mills with classifiers, the mills being of the type comprising a ball &c. containing rotary drum 3 into which the material to be reduced is introduced at one end 6 and from which the reduced material is aspirated from its other end 7 by a current of air flowing through the mill, an extractor fan 16 connected to the output of the classifier 14 aspirates a current of air through the classifier and the mill, the outlet 17 of the classifier for tailings or rejects is connected to a conduit 19 leading to the inlet of the mill and adapted to convey thereto the air current, means 22 ... 25 for feeding the raw material to be reduced are also connected to the conduit, the points of entry of the tailings and of the raw material into the conduit being sufficiently removed from the inlet to the mill to allow the particles to be accelerated by the air current to a speed approximately that of the current before they pass into the mill, and the classifier outlet connection to the conduit and the means for feeding the raw material thereto each terminate in an inclined feed shoot 21, 25 extending into the conduit to form a baffle therein adapted to set up venturi action on the air current. For pulverising coal and delivering the product to a burner the extractor fan aspirates a current of pre-heated air or gas along the conduit and through the mill, and then, together with the finer ground particles, through the classifier and the fan to the burner.