2006 Volume 46 Issue 7 Pages 1014-1019
Recent studies concerning the dioxin emission from the iron ore sintering process have clarified a dominant mechanism of dioxin formation and the substances to promote or to inhibit the reaction. In this paper, a detailed analysis of the exhaust gas at the Oita No. 1 sintering plant has specified the strand positions where dioxins were released into 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 the hearth layer, showing a broad peak containing a large amount of furans. The second release position was located at the point where the melting zone reached the heath layer, showing a sharp peak. Differences in dioxin congeners at the release positions imply a different mechanism of dioxin 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 dioxin emission in the second step.