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Despite the progress in understanding heavy metals behavior during coal combustion, mitigation of heavy metals emissions is still a tough challenge due to a complex character of this phenomenon. Several lists of potentially toxic elements have been presented; in most cases, Pb belongs to the elements with the greatest environmental and human-health concern. The review paper is focused upon the behavior of Pb during coal combustion. with particular attention paid to decreasing its emissions. It summarizes the dominant parameters affecting its redistribution among coal combustion streams. As gaseous emissions can quite easily pass through the particulate control device, attention was paid primarily to Pb distribution between condensed and volatilized phases. A crucial factor enhancing Pb volatility is the presence of organic or inorganic chlorides, which is discussed in detail, including their chlorination mechanisms and interactions with other fuel/flue gas species. Components decreasing Pb volatility and promoting the formation of condensed phases are also discussed (higher levels of moisture, Na, O2 etc.). Factors enhancing Pb volatility, as well as factors facilitating Pb retention, are discussed with the view of fluidized-bed combustion, pulverized-fuel combustion, or co-combustion of coal with wastes.

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The Moravian-Silesian Region is one of the most polluted sites by dust particles in the Czech Republic. Therefore, atmospheric concentrations of heavy metals as cadmium, cobalt, chromium, copper, nickel, lead, antimony, thallium, manganese, iron and zinc, were monitored at 10 localities in the region during summer of 2014. Heavy metals were monitored in 10 particle size classes from 18.3 nm to 9.93 µm. The percentage of the amount of heavy metals in the sum PM at all localities ranged from 0.2-2.5%. It was found that chromium, manganese, iron and zinc were mostly accumulated in dust particles with diameter greater than 1.6 µm. Lead, cadmium and antimony occur mainly in the class below 0.949 µm. These metals are more dangerous for human health, and can have potential carcinogenic effect. The influence of metallurgical industry evaluated on the basis of heavy metals in the individual particle size classes in the air within the Moravian-Silesian Region has not been unequivocally demonstrated.

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