GB278214A - Improvements in and relating to ball mills - Google Patents

Abstract

278,214. Marks, E. C. R., (Traylor Engineering & Manufacturing Co.). Dec. 6, 1926. Ball mills.-In a ball mill of the kind comprising a rotary cylindrical drum provided with one or more screens or grates in the length thereof through which the material passes as it travels from the feed to the delivery end of the drum. the screen or grate comprises a number of concentrically arranged gratebars, each series comprising a number of individual bars, with the bars of all the series radially disposed with respect to the axis of the drum and of uniform size and shape. Fig. 1 shows a mill 1 with a screen 3 adjacent the discharge end and two intermediate screens 3<a>, 3<b>. Figs. 2 and 3 show views of one of the intermediate screens, in which the screen-supporting member 4 is in the shape of a circular diaphragm with a peripheral flange 4<a> secured to the shell 1 between adjacent lining- sections. The diaphragm has an open centre 4<b> and radial lifter-blades 4<c> supporting at their inner ends a circular deflector-plate 4<d>. An annular ring 4e carried by the blades 4<c> has its face 4f flush with the flared edges 4<g> of the blades. The interchangeable grate-bars 5, Fig. 4, are tapered, with retatively wider inner and outer ends 5a, 5b and widened-out intermediate parts 5<c>, the parts 5<a>, 5<b>, 5<c> of adjacent bars abut and the reduced portions 5d form between them elongated openings for the passage of the fine material. Preferably the walls 5d are tapered to form flared spaces between the bars. Two annular series of grate-bars are used in the mill shown, the inner ends of the inner series being supported by the edge of the plate 4<d>, and the outer ends of the inner series and the inner ends of the outer series by the annular ring 4e, while the outer ends of the outer series rest in annular seats in a ring-member 7 secured to the shell 1. A member 6 secured bv a bolt 6<a> to the plate 4<d> takes the inward thrust of the bars. The outer ends of the outer series and the inner ends of the inner series of bars. and the seat portions of the plate 6 and ring 7 are shaped so as to interlock with the grate-bars. Wedge-shaped segments 8 secured by bolts 9 are interposed between the adjacent bevelled ends of the inner and outer series of bars. After assembling, the bars are crowded laterally into close contact by interposed radially-disposed wedge-members 10 secured by bults 11. Preferably the abutting ends of the segmental wedges 8 are rebated to receive the ends of the members 10. Wear-plates 12' may be provided on the member 4 on the side opposite the screen and be held in position by the bolts 9, 11. The screen 3 at the discharge end of the drum is secured to the end wall 1<a> of the mill.