GB337911A - Improvements in grinding or crushing apparatus - Google Patents

Abstract

337,911. Rexworthy, H. S. Sept. 27, 1929. Ball and like mills.- In a tube mill in which rods 38 in segmental sections 36 of aligned, rotary, spiders 24, are provided, a side 31, Fig. 2, of the section is substantially tangential to a central circle and a side 28 is straight or formed by an arc of the interrupted circle forming the inner surface of the peripheral rim of the spider. The spiders 24 are attached to the drum 6 by wedge-bolts 53 and spigots 39, 42, each spigot 39 being clamped between the flanges 20 of the drum and each spigot 42 being surrounded by packing in a hole in the drum and is secured thereto by a bolt 48 and plate 47. The end-plates 7, 8 of the drum, Fig. 1, are provided with trunnions mounted in bearings and doors 55 for the insertion of the rods 38. The drum is driven through a sprocket 21 and the feed falls on the centre of the rods through a scoop 58 and pipe 57. A coarse sieve 17 and fine sieve 16 surround the central part of the drum, the sieve 17 being shorter in length than the sieve 16 so that coarse particles are returned back to the grinding chamber. The circumference of the spiders may be provided with packing rings 33 and stepped portions 26 are provided with scoops 27 to distribute the material to be ground. In a modification the feed tube 57 is provided with helical ribs, the screens are placed in the end plates 7, 8 and the scoops 27 arranged in the centre of the drum. The mill may be attached to the end of the drum of a ball mill, Fig. 8 (not shown), the ground material passing through a centre sieve into a passage communicating with lifting vanes between the two mills, whereby the material is discharged through a central orifice in the ball mill. The mill may be used for pulping material in a tank 88, Fig. 9, the spiders 79 being mounted on a shaft 78 passing through the tank. Pairs of spiders are used which are displaced angularly with respect to each other and the external rims of the spiders are provided with bars 87 which aid in the disintegration of the pulp. The ground material may be removed from the mill by air suction as shown in Fig. 14. Material enters the mill through a hopper 94 and the ground material is carried by the air current up the tube 95 into a chamber 96 from which it is discharged through the outlet 98. A deflector 101 at the end of the pipe 95 and a baffle 97 in the chamber 96 present a tortuous path for the ground material whereby the coarse particles fall to the bottom of the chamber 96 and are returned to the mill through a rotary seal 100. A flap valve 102 prevents choking in the outlet 92 of the mill. Specification 190,941 is referred to.