Analysis of Visibility of Exhaust Gas in the Iron Ore Sintering Plant

Visible smokes of exhaust gas from the iron ore sintering plant give an unfavorable impression on scenery around the Works. In this paper, a mechanism of formation of visible smoke was discussed by detailed analysis of the exhaust gas components and dusts in Oita No. 1 sintering plant. Main substance of visible smoke was mist condensing in the air during cooling of exhaust gas that contains 0.1ppm of sulfuric acid(SO3). Sulfuric acid is considered to raise the dew point that mist condensation became easier and to lower the vaporization of visible mist consist of sulfuric acid solution. Dusts in the exhaust gas are also considered to play a role of the nuclear of mist condensation. This proposed mechanism was confirmed by the test remixing SOx rich gas with desulfurization gas in Nagoya No. 3 sintering plant. Long visible smoke was observed by remixing SOx rich gas with exhaust gas. As a conclusion, enhancement of dust collecting system is not enough to accomplish invisible exhaust gas. Desulfurization equipment is necessary for invisible exhaust gas in the sintering plant.