PURPOSE: To execute treatment safe in terms of environmental conservation without being affected by the zinc and lead content in raw materials by specifying operation conditions, such as specification of an oxygen quantity in a furnace atmosphere when a low activity carbonous material is used and high-temp. air is blown.
CONSTITUTION: The mixture composed of the material contg. zinc, lead and iron oxide and the low activity carbonous material is charged into a rotary furnace. This mixture contains the carbonous material of an amt. above the stoichiometric quantity required for the reduction of the zinc and lead in the material and below 5 times of the stoichiometric quantity. At the time the high-temp. air of 500 to 1000°C is blown to the charge from the discharge end to the final area of the furnace, the quantity of the high-temp. air is so adjusted that the oxygen is stoichiometrically insufficient for the oxidizable component in the gaseous atmosphere of the furnace. ZnO is considerably reduced by the metal iron in the charge and this metal iron is held at 1200 to 1500°C in the charge of the final area of the furnace in such a manner that the metal iron is greatly reoxidized, by which the oxygen partial pressure is adjusted. The temp. and compsn. of waste gases are adjusted in such a manner that the autothermic post combustion of the gases is possible. The waste gases are thus completely combusted by the air outside the furnace.
GURUDASU SAMANTO
DETOREFU SHIYUREEBUTSUSHIYU
KAARUUHAINTSU FUISHIYAA
