Macroscopic behaviors of dioxins in the iron ore sintering plants

The emissions of dioxins to the environmental air from iron ore sintering plants become to be regulated by the new Japanese law against dioxins. The emissions from Japanese sintering plants have been already fairly low levels by large efforts made so far for their reduction. However, substantial and systematic countermeasures are not yet developed and, further, detailed information has not been available on the formation/decomposition of dioxins in the sintering plant. In the present investigation, two different plants were chosen and samplings were made for gaseous, liquid and solid materials at various positions of the processes. Concentrations of dioxins and other compounds of the samples were analyzed. Understanding of the characteristics of the dioxins formation in the sintering process has been attempted on the basis of the analytical results. Macroscopic behavior of dioxins in the sintering and waste gas treatment processes is discussed. Further, the results of the plant test obtained with and without use of recycling materials are reported.