GB615652A - Improvements in or relating to pulverisers - Google Patents

Abstract

615,652. Ball mills. CUNNINGHAM, R. J. Aug. 8, 1946, No. 23494. [Class 59] In a ball mill, the balls are located in the bottom of a cylindrical bowl, and one or more streams of fluid, e.g. water, oil or air, are injected into the bowl so as to impinge on the balls and cause them to rotate. The material to be pulverized may be supplied by the stream or streams of fluid which may be injected tangentially or at an angle. In one form, Fig. 1, air is supplied by a fan 5 through a pipe 4 to the curved bottom 2 of a bowl 1, the feed hopper 8 for the material to be pulverized being connected to the pipe through an airlock 9. The pulverized material is carried away by the air stream through a pipe 11 which, as shown in Fig. 2, may be connected to a cyclone separator 12 from which the air is drawn through a pipe 14 by the fan 5 for re-use. The path of movement of the balls 6 may be controlled by a conical projection 7, Fig. 4, on the bottom of the bowl. In a modification, Fig. 3 (not shown), the material to be pulverized is supplied through a separate pipe from a hopper at the side of the bowl, and an adjustable cone is mounted in the upper conical portion 10 of the bowl to control the outflow velocity. Booster air may be supplied through a pipe entering at the side of the bowl. In a further modification, Fig. 5 (not shown), the bowl has a flat top and the discharge pipe is surrounded by guide vanes 19 which support an inverted conical member 20 communicating with a valve-controlled tube 21 and surrounded by an adjustable conical member 22. In a second form, Fig. 6, the mill comprises two superposed grinding chambers 23, 24 separated by a partition 25 having a central opening 26 for the passage of ground material. Pressure air is supplied through pipes 4 and 30 to effect rotation of the balls 6 and 29 respectively. A deflector plate 31 is mounted on a spindle 32 extending through the opening 26. In a third form, Fig. 7 (not shown), suitable for wet grinding, the ground material is carried away by the water through a pipe fitted in the side of the bowl. If the material is to be dried whilst being ground, hot air is used for the fluid stream. The bowl may be vibrated by electrical or mechanical means when using heavy balls.