To prevent compaction of powder even in a hygroscopic raw material or the like of which the density is easy to change by action of external force, and to allow fixed amount supply of the raw material via an air flow conveying means without generating bridging inside a raw material tank.
This device is provided with the raw material tank 12 for storing a granular raw material 11, a rotary scraper 13 provided in a bottom part of the tank 12, a screw feeder 15 for conveying the raw material 11 falling down from an opening 14a formed in a bottom plate 14 of the tank 12 by the scraper 13, and the air flow conveying means 16 for dispersing the raw material 11 conveyed from the screw feeder 15 in an air flow to convey it. The screw feeder 15 is provided with a pair of right-hand-threaded and left-hand-threaded screw shafts 42, 43 synchronization-rotated reversely each other and arranged in parallel under a meshed condition, and tip parts of respective screw blades 46, 47 are formed into sharpened tips, in the pair of screw shafts 42, 43.
HIGASHIJIMA YASUHIRO
FUKAMI KAZUYUKI
HAGA ARATA
