PURPOSE: To generate stable fluidization, by providing a granular refractory- accumulated layer where porous gas-dispersing plate having layer penetrating holes at the introducing port of a fluidization reducing gas into a furnace, while coarse grain refractory made more coarse in diameter than that of penetrating holes are placed at the lowest part thereon and small grain refractory is arranged at the top most layer.
CONSTITUTION: A gas dispersing plate 3 with dispersing holes 3a having larger diameter than about 3mm at the fluidization reducing gas introducing port 8 is provided in a fluidized bed type preliminary reducing furnace 1. The regulated flow layer 12 composed of granular refractory accumulated layer where coarse grain refractory 13 of about 8mm diameter is distributed at the lowest part on the gas dispersing plate 3 and small grain refractory 14 consisting of about 1mm diameter grain regulated to the size not fluidizable even when a powdery particulate ore material in the furnace reaches a fluidization starting speed, is placed.
HAMADA HISAO
INATANI TOSHIHIRO
KATAYAMA EIJI
TSUCHITANI NOBUO
KADOTO MITSUO
FUJITA TSUTOMU
HAMADA SHIYUNJI
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