The Occurrence of Selected Radionuclides and Rare Earth Elements in Waste at the Mine Heap from the Polish Mining Group

The paper presents the results of research on rare earth elements (REY) and selected radionuclides in barren rocks deposited on a heap at a mine belonging to the Polish Mining Group (the largest producer of hard coal in EU countries). The maximum concentration of REEs determined in silstones was 261.6 mg/kg and in sandstones 221.2 mg/kg. The average uranium and thorium content in silstones was 6.8 mg/kg and 11.6 mg/kg, respectively. On the other hand, the samples of burnt coal shales contain on average 3.5 mg/kg of uranium and 9.7 mg/kg of thorium. In all coal waste samples, the REE values are higher than in hard coal (15.7 mg/kg). Carriers of REY, uranium, and thorium in coal waste are detritic minerals: monazite and xenotime, which are part of the grain skeleton of barren rocks. Coal waste samples are characterized by a variable distribution of REY concentrations as well as a variable content of radionuclides. The Ra-226, Ra-228, and K-40 measurements in the investigated samples were performed using the gamma spectrometry technique. The concentrations of the analyzed isotopes differed depending on the mineralogical composition of the investigated samples. The present study results may be important in determining the possibility of utilization of wastes of barren rocks stored in the mine heap and in assessing environmental and radiological hazards.