GB391231A - Improvements in or relating to multi-roll grinding mills - Google Patents

Abstract

391,231. Roller and roller-and-breast mills. MACCALLUM, A. E. G., 35, Garratt Lane, Wands worth, London. Oct. 27, 1931, Nos. 29782 and 29783. [Class 59.] In a roller mill a hopper co-operating with the grinding roll is divided into compartments containing a grinding element or elements so arranged that multiple grinding can be effected within the hopper by transferring material under treatment from one compartment of the hopper to the other. As shown in the Figure, a hopper 3 with base 4 is pivotally mounted on a rod 26 and is divided into two compartments A, B by a partition 5, the end of which houses a grinding bar 7 adapted to be pressed into contact with a roll 1 by means of screwed rods 8. A roll 10, which may be reciprocated, is loosely mounted in the compartment A and is rotated bv frictional contact with the roll 1. Stirrers 19, 20 are mounted in the compartment A, B respectively and are independently driven. A valve-controlled outlet 30 is fitted to the chamber B and a spring-pressed scraper 32 removes the paint &c. adhering on the roll 1. A slidable gate 11, movable by a rod 12 is adapted to partially cover an orifice in the partition 5 and forms a weir over which the paint &c. collected in the chamber B returns to the chamber A for regrinding. Powder and liquid are fed into the chamber A and are mixed by the stirrer 19, the roller 10 crushing any lumps contained therein. The mixture passes under the grinding bar 7 and gradually fills the chamber B from which it passes over the weir to the chamber A for regrinding. When the grinding is complete the material is removed through the orifice 30. The mill is cleaned by withdrawing the scraper 32 so that the unground material is removed by a scraper 36. The hopper is then unclamped from the framework 2 and revolved on the rod 26, the loose roll 10 being supported on guides 29. In a modification the hopper is divided into three compartments and the grinding bars may be mounted radially with respect to the roll 1. The hopper may be applied to the last roll of a series, a separate mixing and feed-roll being furnished for the first roll of the series. The hopper base and roll may be heated or cooled. A narrow grinding bar may replace the scraper 32 and a tray, preferably provided with partitions near the end thereof, may be provided to collect the material passing under the bar. The coarse material collected in the end compartment is returned for regrinding.