GB313690A - Improvements in or relating to crushing mills - Google Patents

Abstract

313,690. Loesche, E. C. April 14, 1928. Roller-and-ring mills; ball-and-ring mills.- A mill for grinding coal &c. comprises a concave dish 11 rotatable on a vertical spindle 8, the grinding surface of the dish ascending from the axis to the circumference and rolls 12 which are retained in a fixed working position and rotate in grinding engagement with the circumferential portion of the dish, the ratio of the diameters of the rolls and dish being not more than 1:2.5. The dish is driven through bevel gears 9 and the feed is supplied either through a funnel or through a pipe 25 provided with a rotary feed wheel 26. The roller 12 is mounted on a hinged door 15, the roller spindle being pivoted at 14 and is extended to engage a screwthreaded rod 20 on which is a spring 22 to regulate the pressure of the roll on the dish and a nut 23 to adjust the position of the roll relatively to the dish. An air blast enters at 30 and circulates in a chamber 32 so formed between the casing 2 and outside surface of the dish that the cross sectional area remains constant. The air blast and finely-ground material pass upwardly between the casing 3 and a sleeve 35 and pass through louvres 36 to an outlet pipe 31, the heavier particles falling into a hopper 37 where they accumulate and eventually open flap valves 38 to descend on to the dish 11 to be reground. In a modification, the surface of the dish is conical and the rollers are frusto-conical, the pressure being applied by a spring without the limit nut 23, Fig. 1. The roller may be a ball 40, Fig. 4, loosely rolling on the face of the dish 11 and retained by arms 41 fixed to the casing 3, the arms preferably being provided with antifriction rollers 42 located in position for engaging the balls 40. The upper margin of the dish may be extended by means of a ring 44, Fig. 6, which may be adjustable in height.