GB847281A - Improvements in pulverising mills - Google Patents

Abstract

847,281. Ball-and-ring mills. BABCOCK & WILCOX Ltd. Dec. 3, 1958 [Dec. 6, 1957], No. 37997/57. Class 59 In a ball-and-ring mill having an upper non-rotary grinding ring and a lower rotary grinding ring disposed within a casing, the upper ring is urged towards the lower ring by means of a plurality of hydraulic power devices mounted outside the casing and acting on the upper ring through circumferentially spaced thrust members or plungers. As shown in Fig. 1, a non-rotary upper grinding ring 12 is urged towards a rotary lower grinding ring 26 by means of equi-angularly spaced thrust members 65 the lower ends of which engage recesses 69 in a ring 10 supporting the grinding ring 12 and the upper ends of which are connected through a lever 74 and a link 75 (not shown) to the upper ends of thrust rods 90 movable in hydraulic cylinders 80 pivotally connected to the sides of the mill casing 1. A windbox 36 is provided for supplying entraining air to the mill. The thrust rods are provided at their lower ends with replaceable wear resistant heads and at their upper ends with eyes 70 to facilitate removal, by lifting tackle, of the thrust rods when access to the grinding balls is desired for replacement purposes. Alternatively, Fig. 4 (not shown), the thrust rods may be pivotally connected at their lower ends to a support ring for the upper grinding ring so that the support ring and grinding ring may be removed by lifting tackle or by means of the hydraulic cylinders. In another modification, Fig. 5, a nonrotary upper grinding ring 133 is urged towards a rotary lower grinding ring 131 by means of hydraulic cylinders 142 the plunger 160 of each of which acts upon a thrust rod 150 provided with a head 140 which engages a recess 139 in a thrust pad 138 supported on a projection 135 provided on a thrust ring 134. Each thrust rod is slidably mounted in bearings 148, 149 in an extension piece 145 which is removable with the thrust rod through an opening 161 which is normally closed by a cover plate 162. Means are provided for lubricating the bearings 148, 149. A hydraulic system, Fig. 6, for operating hydraulic cylinders 100, 101 and 102 which provide the means for urging one grinding ring towards the other includes an intensifier 104 supplied on the low pressure side with entraining air from the mill, a spring or weight-loaded accumulator 113 and a pressure gauge 115 provided with contacts 116, 117 which operates to shut down the motor driving the mill when the pressure of the fluid supplied to the cylinders falls below a lower predetermined value or rises above an upper predetermined value. Specifications 334,058, 396,614 and 523,753 are referred to.