GB575376A - Improvements in pulverisers - Google Patents

Abstract

575,376. Ball - and - ring mills. BABCOCK & WILCOX, Ltd. March 15, 1944, No. 4804. Convention date, April 1, 1943. [Class 59] In a ball-and-ring mill for pulverising coal &c. of the kind described in Specification 523,753 and comprising fixed and rotary upper and lower grinding rings 21, 19 separated by an intermediate circular row of balls 20, the pulverised material being removed from the grinding zone by an upward stream of air supplied from a wind-box 32 which is eccentrically arranged to ensure uniform distribution to the annular throat 34, a constant air velocity through the throat is obtained by subdividing the latter, by equally spaced lugs 50 of tapered form as shown in Figs. 3 and 4 into a number of passages 51 of substantially uniform crosssection throughout their height. The lugs 50 are inclined as shown to increase the length of the passages 51 and to give the ascending air a component of motion in the direction of movement of the adjacent part of the rotary grinding ring 19. A portion of the ring 35 forming the throat is formed by a pivoted. relief gate 36 which swings outwardly to permit the passage of large pieces of unpulverised or foreign material, while particles of excessive size or density falling through the throat 34 pass through an opening 41 controlled by a gate 42 into a collecting chamber 40 from which they are removed through door 44.