FI268474

1431239 Tube mills BOLIDEN AB 21 Aug 1974 [27 Feb 1974] 36801/74 Heading B2A The discharge end of a tube mill includes a chamber formed by a partition 18, Fig. 1, having large holes 23 and small holes 22. Ducts 20, 21, Fig. 2, are formed by webs 16. The small holes 22 connect with ducts 20 and large holes discharge a coarse/fine mixture towards a common discharge pipe 25. When a valve 26 is closed (solid lines) duct 21 is closed 'by a valve plate 38 and mixed material is discharged via pipe 25. When the valve 26 is "open" valve plate 37 permits flow via duct 21 of the mixture back to the mill. Mixed material is discharged via the pipe 25 into a hopper 29. Fine material is discharged via a pipe 28 into a hopper 30. In a second embodiment a single valve plate 37', Fig. 3, in its "full line" position permits discharge of mixed material via pipe 25 and in its "dotted line" position returns mixed material to the mill. The discharge pipe has sieve openings 46 to separate water and undesired tines. A spiral arrangement 48 slows down flow and enhances separation. The mill casing has a rubber liner 13, rubber lifters 14 rubber end plates 18, and may be operated autogeneously.