Changes in trace element contents in ashes of oil shale fueled PF and CFB boilers during operation

Behaviour mechanisms and correlation between lead (Pb) and its isotope210Pb in industrial residue as an indicator for waste characterization

“…[51] During the combustion processes, small particles (with micron and sub-micron diameter), finer ash fractions, as well as emitted atmospheric particles will be more enriched with lead compared to particles with larger diameter. [32,33,52,53] Previous studies by AunelaTapola et al, [47] Blinova et al, [32] Realo et al [48] and Vaasma et al [17] show that similarly to coal combustion, oil shale-fired power plants in Estonia are emission sources of trace elements, heavy metals and natural radionuclides. Considerably elevated concentrations of lead (stable and radioactive isotopes) in soil have been detected also near coal-fired power plants and other industrial installations.…”

“…[30,31] These combustion boilers are also equipped with different type of filters (electrostatic precipitators, novel integrated desulphurization filters), which have varying efficiencies precipitating fly ash and binding pollutants from flue gases. The finest ash fractions that are precipitated in the last fields of EPP's are often the most enriched with heavy metals [32,33] and radionuclides [34] and are to some extent emitted to the environment. [35] 2.3.…”

“…The particle size and specific surface area have a direct influence on the concentrations of various heavy metals and radionuclides accumulated in the formed ash fractions. [32,33] Ash fractions collected from various precipitation points demonstrate variations in the total Pb and 210 Pb concentrations (Figures 3 and 4).…”

“…Similar enrichment trends have been detected in other available studies. [32,33] Previous research by Blinova et al [32] has concluded that hazardous elements can accumulate in soils; so the application of fly ash, especially in agriculture, must be monitored for the content of heavy metals (especially As and Pb) in topsoil.…”

“…Similar trends in the boilers of the Narva Power Plants have been found and published previously. [17,33,34,47,48] The concentrations are quite evenly distributed in the filter ashes of CFB boilers, with one exception in the total Pb value (Figure 4). It may be due to a random deviation or an error connected with the sample collection or preparation.…”