PURPOSE: To stably operate a heat treating apparatus over a long period of time, by bypassing a part of an exhaust gas containing fine dust at high concn. in a lowermost stage cyclone through the preheating zone in the upper part.
CONSTITUTION: A dust concentrator 14 is provided to the outlet of a lowermost stage cyclone 6 and dust concn. in an exhaust gas is increased to partially take the exhaust gas and this exhaust gas is directly sent to an exhaust gas 3b through a bypass conduit without passing the same through the next upper cyclone. By this mechanism, the amount of fine particles in a calcined product passing through a re-carbonating reaction zone is reduced and the adhesion and the accumulation of a reaction product are prevented and the stable operation as well as the continuous long-term operation of a heat treating apparatus are maintained.
YAMASHITA KOUSUKE
TAODA KIYOMICHI
OOSAKA HIROMI
