Natural radioactive elements and heavy metals in coal, fly ash and bottom ash from a thermal power plant

Abstract

Summary The composition of coal used as fuel at a thermal power plant and those of the fly and bottom ashes it produces were determined. Radioactive elements were analysed for by alpha and gamma spectrometry, while sulphur, carbon and nitrogen were determined by burning. Heavy metals were quantified by X‐ray fluorescence spectrometry and inductively coupled plasma atomic emission spectroscopy (ICPAES). The low sulphur content of the coal (0.68%) gives rise to fly ash containing only 0.21% of this element. The radiochemical analyses performed by alpha spectrometry revealed that most of the uranium remains in the solid residue resulting from disaggregation of the sample with Na2CO3 in the separation process. Also, the gamma spectrometric results show that the elements from the 4n and 4n + 2 series and 40K concentrate in fly ash, the mean particle size of which is the smallest of all the residues assayed.