PURPOSE: To make efficient and economical sepn. and recovery by providing dams to increase the reduction time of dust in the stage of reducing and evaporating the dust contg. Fe2O3, ZnO, PbO, in a rotary kiln and separating and recovering Zn and Pb.
CONSTITUTION: The rotary kiln 1 is trisected in the longitudinal direction by the intermediate dams 6, 7 to the 1st reducing atmosphere zone A (about 650°C), 2nd reducing atmosphere zone B (about 1,200°C) and oxidative atmosphere zone C (about 1,200°C). The dust contg. Fe2O3, ZnO and PbO is charged together with a solid carbonaceous reducing agent in this state into the rotary kiln 1 by a chute 2 and is moved in the kiln. The moving time is increased by the dams 6, 7, by which the reducing efficiency is improved. The ZnO and PbO are actively reduced and evaporated so as to be separated from the dust and are then reoxidized by oxygen to ZnO and PbO which are discharged together with an exhaust gas from an inlet 1a. The Fe2O3 is made into clinker together with the residual slag in the dust and is discharged from an outlet 1b.
TOSHIN STEEL CO
NIPPON KOKAN KK