MERCURY IN COALS AND FLY ASHES FROM REPUBLIKA AND BOBOV DOL THERMOELECTRIC POWER PLANTS

Feed coal and fly ash samples were collected at Republika and Bobov Dol thermoelectric power plants (TPPs). The fly ashes (FAs) were collected from three rows of the hot-side electrostatic precipitators (ESPs) array. Each sample was wet-screened at 100, 200, 325 and 500 mesh. The coals and fly ashes were characterized with regard to their petrological and chemical composition (including mercury content) and to their surface area properties. The calculated enrichment factor (EF) shows that the Hg concentrations in the bulk coal samples from Republika and Bobov Dol TPPs are 2.19 and 1.41, respectively. In some coal size fractions the EF can be up to 4 times higher than the Clarke value. The calculated EF for fly ashes shows that the Hg concentrations in the bulk samples studied are lower (between 0.03 and 0.32) than the Clarke value. The most enriched in Hg are the fly ashes from the 3rd ESP row of Republika TPP. The Hg distribution in bulk FAs taken from different rows of the electrostatic precipitators of both TPPs studied shows well established tendency of gradual increase in the Hg content from the 1st to the 2nd and 3rd ESP rows. The correlation between Hg content and surface area, mesopore and micropore volume of fly ashes was also done in the present investigation.