Abstract
Recent studies concerning the dioxins emission from the iron ore sintering process have clarified a dominant mechanism of dioxins formation and the substances to promote or to inhibit the reaction. In this paper, a detailed analysis of the exhaust gas in Oita No.1 sintering plant has specified the strand positions where dioxins were released to the exhaust gas. The release of dioxins was detected at two different positions. The first release position was located at the point where the drying zone reached to the hearth layer, showing a broad peek containing a large amount of furans. The second release position was located at the point where the melting zone reached to the heath layer, showing a sharp peek. Differences in dioxins congeners at the release positions imply different mechanism of dioxins formation. The dioxins of the second release are considered to be formed in wind boxes at temperatures of 300°C or more. Controlling the burn through point to the discharge end is supposed to be effective for decreasing the dioxins emission in the second step.
