GB1087526A - Improvements in or relating to rotary tubular grinding or crushing mills - Google Patents

Abstract

1,087,526. Ball &c. mills. MITCHELL ENGINEERING Ltd. and G. POLE. Aug. 13, 1965, No. 34838/65. Heading B2A. [Also in Division F2] A tube mill for pulverizing coal comprises a closed rotatable grinding chamber 10, Fig. 1, having opposite end walls, as 12, respectively provided with a feed opening 15 and a discharge opening, each associated with a stationary hopper, a pressure chamber 4 surrounding the junction between the end of each hopper and the opening in the respective end wall. One part of the pressure chamber is fixed relative to the hopper and the other part rotates with the grinding chamber, and inter-engaging sealing faces are provided between the relatively rotating parts of the pressure chamber. An atmosphere under pressure is supplied to the pressure chamber to prevent fine material escaping from the grinding chamber through the junction between the feed opening end and the end of the hopper. A vent pipe 35, Fig. 3, leads from either or each pressure chamber to a zone of lower pressure within the confines of the mill. As described, sealing between a ring 23 and a sealing plate 13 is maintained by hydraulic rams 28, and a resilient sleeve 22 encircled by cables 26 tightened by tumbuckles seals between a ring 21 and the ring 23. The pressure chamber is divided by a partition 30, Fig. 2 on the ring 21 and a rib 32 on a wall 14 into an outer zone between the discharge end of the hopper and the wall 14, and an inner zone containing sealing faces 13 and 24, so that powdered coal escaping through the junction between the hopper and the extension wall drops into the outer zone. The vent pipe 35 extends from the bottom of the ring 21 to an opening at 36 in the side wall of the hopper. Pipes 37, Fig. 4, secured to four ports in the ring 21 supply pressure air to the chamber 4 at greater pressure than that in the grinding chamber. Feed is effected via openings 38 in the sides of the hopper.