Major, trace, and natural radioactive elements in bituminous coal from Australia, Romania, Russia, South Africa and Ukraine: A comparative study

Five samples of bituminous coal collected from different basins (Australia, Romania, Russia, South Africa and Ukraine) have been investigated by using different analytical techniques. Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Mo, Sn, In, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Lu, Hf, Ta, W, Hg, Th and U have been determined by neutron activation analysis, K-40, U-238, U-235 and Th-232 have been measured radiometricaly, H, C, O, N, and S have been dosed by dynamic flash combustion, while gravimetric methods have been used to measure moisture and ash content together with calorific power. Major mineralogical fractions have been investigated by means of X-ray diffraction. The results have shown significant positive correlations between radiometric and activation analysis results, between calorific power and carbon, nitrogen and hydrogen concentrations and negative significant correlations between calorific power and ash content. According to the Romanian Regulations, only Cr and Ni for Romanian coal exceeded the minimum threshold to be considered unpolluting elements. The distribution of rare earth elements, La to Th ratio, as well as of Sc, La and Th together with Co, Hf and Th have confirmed that, irrespective of sample sources, the mineral part of coal has a composition close to that of the upper continental crust.