GB150997A - Improvements in mills for grinding and disintegrating materials - Google Patents

Abstract

150,997. Hardinge, H. W. Sept. 11, 1919, [Convention date]. Ball and like mills. - A conical tube mill for grinding or disintegrating ores &c. and comprising a revolving barrel or drum with inlet and discharge passages is provided with means adjacent the discharge passage to separate the coarse from the fine particles and to return the coarse particles to the larger part of the barrel for further grinding. The conical outlet portion of the mill is surrounded by a conical classifying-hood which revolves with the barrel or drum and into which part or all of the disintegrated material is discharged either through an opening at the apex of the outlet portion or through suitable openings in its wall. The coarse particles are returned to the mill by one or more conveyer pipes extending from the base of the hood to preferably at a point in rear of the base of the outlet cone, while the fine particles are discharged from the apex of the hood or through its walls. Fig. 1 shows a mill for wet grinding. The ground material is discharged from the outlet trunnion 13 into a launder 18 and also through openings 17 into the conical hood 19. The fine particles flow over the apex of the hood with the water into a launder 20, while the larger particles collect at the base of the hood and are returned to the mill 14 by a helical conveyer-pipe 21. For dry grinding, the hood is made of foraminous material through which the fine particles pass into a receiving-hopper. In a modification, Fig. 3, the conical outlet portion 12 is not perforated and all the material is discharged from the apex into the hood 24 from which the fine particles flow over into a launder 25. In another arrangement Fig. 4, the outlet portion 12 is provided with a transverse baffle 26, preferably nearer the base than the apex of the cone. The baffle may consist of a screen or a perforated disk with or without a central opening, or an imperforate disk with a central opening. The coarse and fine particles pass into the conical portion beyond the baffle, where they are classified, the fine particles flowing out through the trunnion 13 while the coarse particles are returned to the barrel 14 by a conveyer-pipe 27.