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Effect of selected additions on de novo synthesis of polychlorinated dioxins and furans

Wielgosiński G., Namiecińska O., Łechtańska P., Grochowalski A.

Ecological Chemistry and Engineering. S

2016

Vol. 23, nr 2

249--257

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans are generally considered the most dangerous chemical substances known to man. Although they have never been the product of purposeful human activity, yet they are formed in many chemical and virtually all thermal processes. Research on the occurrence of dioxins in the environment, their release into the environment, ways of formation and methods of reducing their emissions lasts since the late seventies of the last century. Currently, we know three basic pathways of dioxins formation in thermal processes, the most important of them being the so called de novo synthesis which occurs outside the combustion zone at 200-400°C in the presence of catalysts (eg copper) and oxygen from the products of incomplete combustion including carbon black and chlorine or chlorinated compounds. It is well known that some metals like copper catalyze the de novo synthesis, while others decompose dioxins and furans formed previously. The formation of dioxins resulting from the de novo synthesis was studied through analysis of the effect of the type of metal on the course of the de novo synthesis. The influence of the addition of sulfur, nitrogen and alkali metals on this synthesis was also examined because some reports in the literature refer to inhibitory effect of these elements.

The use of ammonium sulfate as an inhibitor of dioxin synthesis in iron ore sintering process

Łechtańska P., Wielgosiński G.

Ecological Chemistry and Engineering. S

2014

Vol. 21, nr 1

59--70

The main air pollutants in the sintering process of iron ore are polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and harmful dust. Ore sintering on sinter strands is one of the first technology steps in the ironworks. It is a process in which iron ore is crushed, subjected to annealing and mixed with appropriate additives, and then sintered in order to produce sinter which is the main component of iron in the blast furnace process. PCDD/Fs emissions were measured and the addition of ammonium sulfate as an inhibitor of the synthesis of dioxins in the sintering process of iron ore was studied.

Do głównych substancji zanieczyszczających powietrze w procesie spiekania rud żelaza należą polichlorowane dibenzodioksyny i polichlorowane dibenzofurany (PCDD/PCDF), a także szkodliwe pyły. Spiekanie rud na taśmach jest jednym z pierwszych węzłów technologicznych huty o profilu surowcowym. Jest to proces, w którym ruda żelaza jest kruszona, poddawana wyżarzaniu i mieszana z odpowiednimi dodatkami, a następnie spiekana w celu otrzymania spieku, który stanowi główny składnik żelazowy w procesie wielkopiecowym. W aglomerowni wykonano pomiary emisji PCDD/Fs, a także badano dodatek siarczanu amonu jako inhibitora syntezy dioksyn w procesie spiekania rudy żelaza.