Rare earth elements in fly ashes created during the coal burning process in certain coal-fired power plants operating in Poland – Upper Silesian Industrial Region

The subject of the study covered volatile ashes created during hard coal burning process in ash furnaces, in power plants operating in the Upper Silesian Industrial Region, Southern Poland. Coal-fired power plants are furnished with dust extracting devices, electro precipitators, with 99–99.6% combustion gas extracting efficiency. Activity concentrations ofTh-232, Ra-226, K-40, Ac-228, U-235 and U-238 were measured with gamma-ray spectrometer. Concentrations of selected rare soil elements (La, Ce, Nd, Sm, Y, Gd, Th, U) were analysed by means of instrumental neutron activation analysis (INAA). Mineral phases of individual ash particles were identified with the use of scanning electron microscope equipped with EDS attachment. Laser granulometric analyses were executed with the use of Analyssette analyser. The activity of the investigated fly-ash samples is several times higher than that of the bituminous coal samples; in the coal, the activities are: 226Ra – 85.4 Bq kg−1, 40 K–689 Bq kg−1, 232Th – 100.8 Bq kg−1, 235U–13.5 Bq kg−1, 238U–50 Bq kg−1 and 228Ac – 82.4 Bq kg−1.