GB268263A - Improvements in or relating to grinding mills - Google Patents

Abstract

268,263. Loesche, E. C. Dec. 29, 1926. Roller-and-ring-mills; ball-and-ring mills.- Relates to mills for grinding rock, ore, cement, &c. and of the type comprising a casing contain. ing a rotary container in the form of a shallow bowl or dish against the surface of which crushing rollers or balls are pressed, with a blower to produce a current of air to separate the fine from the coarse particles, or a sieve. Means are provided for practically continuously removing the material being ground from the rotary container, separating the fine from the coarse particles, removing the fine particles and allowing the coarse particles to pass below the container, and returning the coarse particles to the container to be reground. As shown in Fig. 1, the bowl 6 is mounted on a vertical shaft 4 within a casing 1 having an intake passage 2 for a current of air and an outlet passage 3. The crushing-rollers 7 are mounted on spring-pressed rockers S. The crushed material is thrown outwardly from the container into the current of air passing up through the annular passage between the casing and the container, the fine particles being carried out at the outlet 3 while the coarse particles fall down the shoot 12 and are returned by suitable means to the container. In a modification, Fig. 2, conical rings 30 spaced apart form each other are provided below the annular passage 29, and the container 22 is provided with holes 32 and has forwardly-extending scoops 33 fixed to its under side. Air enters through a. tangential pipe 19 and passes through the passages 31 between the rings 30 and through the annular passage 29 thereby carrying the fine particles away through the outlet 20, while the coarse particles slide downwardly over the rings 30 and are raised by the scoops 33 through the holes 32 to the central part of the container. Fig. 4 shows an arrangement in which the fine particles are separated by a stationary conical sieve 37 surrounding the container 39. The particles passing through the sieve fall into the bottom of the casing 36 and are discharged by screw conveyers 48, while the coarse particles pass down the shoot 44 into a trough 45 whence they are raised by an elevator 46 and returned through the feed-funnel 42 for further grinding. Or the coarse particles not passing through the sieve may be returned to the container by means of holes therein and scoops on the under side of the container.