GB849340A - Improvements in and relating to vibratory grinding - Google Patents

Abstract

849,340. Ball mills. PODMORE & SONS Ltd., W. Feb. 10, 1959 [Feb. 10, 1958], No. 4212/58. Class 59 A method of grinding consists in introducing air at the base of a grinding chamber whose lower portion at least is conical, the grinding chamber containing grinding media and the charge of the material being ground, subjecting the grinding chamber to a vibratory action which is communicated thereby to the grinding media, and the air flow being mixed with the charge, air loss from the charge at its surface being replaced by air entering at the base, so that the movement of the media and the fluidization of the charge by the air rising through it combine to facilitate the grinding action. Apparatus for carrying out the method comprises a chamber 10 containing grinding media and mounted on a platform 12 carried on springs 13 attached to a platform 14 vibrated by a unit 15. The chamber has one or more air inlets 16 and one or more flexible outlet ducts 20. Each duct 20 leads to a classifier 21 from which a valve-controlled pipe 22 returns oversize material to the chamber 10. The finer material from the classifier passes to a separator such as filter bags or, as shown, to a cyclone 27 where fine particles are collected in a bag 28. The air stream and dust passes from the cyclone to a dust collector 30 and dust deposited in a bag 31. The material to be ground is fed from a hopper 37 by means of a vibratory or other feeder 36 into an inlet shoot 35 having a perforated bottom plate. One or more slidably mounted tubes 40 opening to the atmosphere control the velocity of the air flows. Each air inlet may incorporate a pressureresponsive valve controlling an electrically-driven apparatus for feeding the material to be ground either along with the air or through a separate inlet