Effect of additives on the dioxins emissions in the iron ore sintering process

As an initial step of collaborative studies carried out by the SDD project, some series of sinter-pot tests were carried out to examine formation/decomposition behavior of dioxins in the sintering bed. Test method was first assessed from a view of accurate determination of dioxins discharged in the outlet gas. It was confirmed that the pot test is an effective way to measure dioxins emissions from the sintering process. Then, the effect of additives, ie., PVC, NaCl, oil, mill scale, anthracite and dusts form steel works, was evaluated by the pot tests. They were chosen in terms of organic/inorganic chlorine sources, volatile matters convertible to "soot" during combustion and so forth. Based on the results, possibility of de novo synthesis of dioxins from the electrostatic precipitator (EP) dust and soot formed/trapped in the sintering bed was discussed. Further, accumulation behavior of dioxins in the raw materials due to the recycle use of dusts formed in the waste gas treatment process was examined using raw materials initially containing the dust from an electrostatic precipitator of a sintering process and C-13-labeled reagents of 08CDF, 2378-T4CDF and 246-CP.