GB693418A - Apparatus for removing dust from granular material - Google Patents

Abstract

693,418. Pneumatic separating; centrifugal separators. VOGEL W. Jan. 14, 1952. No. 1031/52. Classes 23 and 117. In apparatus for removing dust from granular material by sifting in an air current which traverses a sieve along which the material moves forward, the sieve is divided into zones which are traversed consecutively by the air current, and cyclone separators are provided for separating the dust from the air current between each pair of zones. As shown the material is fed from a hopper 1 to a sieve 2 which is vibrated to feed the material along it. The apparatus is divided into five zones traversed in succession by the air current, each zone comprising four sections which are traversed in parallel by the air current. Below and above each section are pyramidal pipes 3 and 4 respectively, which are connected by rubber sleeves 5 to the part of the housing which vibrates. Pipes 6, which are provided with suction valves 7, are fitted to' the bottom pipes 3 of the sieve zone at the exit end and are connected to a collecting bunker 10. The other pipes 3 are connected to cyclone separators 8 which are also connected through paddle wheels 9 to the bunker 10. The top pipes 4 are connected to cycline separators 11, each group of four separators being connected through an individual paddle wheel 12 to a common pipe 13 connected to the bunker 10 and provided with a worm conveyer. Each group of four separators 11 is connected to the suction pipe 16 of a fan 17, and the pressure pipes 18 of those fans which are connected on the suction side with the first to the fourt sieve zones lead into the lower cyclone separator of the immediately following sieve zone. The pressure pipe 19 of the last fan 17 supplies air to a dust-removing device not shown. The fans draw an air current through the sieve in opposite direction to the movement of the material being sifted, the coarse material falling through the sieve to be separated in the cyclone separators 8 or falling down the pipes 6 and the dust is carried away by the air current above the sieve having its coarser constituents removed by the cyclone separators 11. The fans 17 are so arranged that the throughput of the second to the fifth fan is a little greater than that of the immediately preceding fan to ensure that a sub-atmospheric pressure is maintained in the space above the sieve, and for this reason paddle wheels 20, 21 are provided at the entry and exit of the sieve. For wet material the pipes 3 and 4 may be provided with heating jackets supplied with hot water or steam preferably circulating in the same direction as the air current.