Patent GB-786219-A (GB)
Title: Improvements in grinding mills
IPC: B02C17/07
Filed: 1955-05-04
Abstract: 786,219. Ball mills. BARGERO ,  C. May 4, 1955 [May 6, 1954], No. 12954/55. Class 59 A grinding mill of the type comprising an elongated cylindrical drum rotating about a horizontal axis, is plurality of radial partitions extending longitudinally throughout the entire length of the drum to define a plurality of longitudinally-extending main chambers of circular sectorshaped cross-section, grinding bodies in the main chambers; an inlet opening at one end of the drum for charging the material to be ground and associated with one of the main chambers, an outlet opening at the other end of the drum for discharging the ground material and associated with at least one of the remaining main chambers, and means connecting the said main chambers therebetween so as to allow conveying the material being ground from the inlet opening towards the outlet opening of the drum is characterized in that the connecting means comprise arcuate channels arranged externally of the outer periphery of the drum and communicating with two successive main chambers through openings provided in the peripheral walls of the drum. As shown, material to be ground is supplied to a chamber A through an opening 22 and the finely ground material is discharged from a chamber C through an opening 23. Chambers A and B communicate at the end of the mill near the outlet opening 23 and at its central portion through grids 25 provided in the casing of the chamber A, each grid giving access to an external arcuate channel 26, Fig. 2, ending in an opening 27 for discharging the material into the chamber B. Within an annular chamber 30 provided about the drum at the end of the mill near the inlet opening 22 is a grid 29, Fig. 3, provided in the wall of the chamber B together with a transverse partition 31 (not shown) and a sieve 32. The material  issuing from the chamber B reaches the sieve 32 through which fine material passes to be discharged into the chamber C through an opening 34, Fig. 4, while material not passing through the sieve is returned through an external conduit 33 to the chamber A. In a modification, Figs. 6 to 10 (not shown), the mill is divided into four sector-shaped chambers, two diametrically-opposite chambers serving for fine grinding, and comprises intermediate openings for withdrawing material from the first chamber and each associated with a grid and a sieve for conveying the material to the second chamber through an external arcuate channel and to the two third chambers through a helical conduit. A grid-controlled opening for withdrawing material is provided at the end of the second chamber and is connected, via an external annular channel and two openings, to the two third chambers. In a modification of this last construction, Figs. 11 to 14 (not shown), the mill comprises intermediate openings for withdrawing material from the first chamber and passing it. via grids and external annular channels, to the second chamber, and an intermediate opening for withdrawing material from the second chamber and associated with a grid and sieve for passing material selectively to the third chambers through a helical conduit or returning' it to the second chamber through a further arcuate channel.