GB241268A - Improvements in or relating to dry grinding or crushing apparatus - Google Patents

Abstract

241,268. Hardinge, H. W. July 15, 1924. Ball mills.-In dry grinding or crushing apparatus comprising a rotary chamber grinding elements and having axial inlet and discharge openings, an air-eduction conduit is provided in the chamber distinct from the discharge opening and having its mouth below the level of the non-floating material in the chamber and serving as an additional exit through which the air carries finer material than that which passes out by the discharge opening. As shown, the grinding- chamber A is tapered at each end and the axial inlet and discharge openings Band C are formed in cylindrical extensions of the chamber which rest in bearings D, D<1>. The air-eduction conduit F extends out through the discharge opening C and is connected to a suction fan F which delivers into a separator H. The fine material is carried out through the conduit F by the air current, and the coarser material passes out through the annular space between the conduit F and the internal wall of the passage C into a collecting- chamber or classifier K which is in the form of two cones placed base to base and rotates with the chamber A. A return conduit L for returning the coarser material to the chamber A extends through the conduit F and at the middle of the classiner is provided with branches L<1>, L<2> extending through the conduit F to the periphery of the classifier where they are bent in a forward direction to form scoops. The branches L<1>, L<2> are supported by brackets L<3> from the classifier so as to rotate therewith, and the conduit L is supported by a spider L<4> from the interior of the conduit F which is supported by a spider F<1> from the wall of the opening C. The coarse material is picked up by the branches L<1>, L<2> and is forced through the conduit L by an air blast from a nozzle N. Any fine material passing through the opening C is returned to the chamber A by an air blast from a pipe N<1>. The outlet from the separator H is connected by a conduit M to the nozzle N and pipe N<1>. The classifier is closed at the outer end by a stationary disc K', and the nozzle N is longitudinally adjustable by a sleeve N<2>. Internal shallow ribs R sloped backwardly are provided in the opening C to return any grinding-elements or large particles. A separate blower may supply air to the nozzle N and pipe N<1>. The air may be returned from the separator H to the inlet B of the chamber A.