Geochemistry and origin of lead and selenium in the no. 6 coal from the junger coalfield, north China

The concentration, occurrence, and geological origin of lead and selenium in the main minable coal seam (No. 6 Coal) from the Junger Coalfield were studied using inductively coupled-plasma mass spectrometry, instrumental neutron activation analysis, scanning electron microscope equipped with an energy-dispersive X-ray spectrometer, and optical microscope. The results show that the average concentrations of Pb and Se in the No. 6 Coal are as high as 35.7 mu g/g and 8.2 mu g/g, respectively, which are much higher than those of coals from North China, Guizhou of China, China, and USA. In addition, their enrichment factors are up to 2.4 and 68.1, respectively. Lead and selenium mainly occur in galena, clausthalite, and selenio-galena. These minerals occur as cell-fillings of coal-forming plants and are of chemical sedimentary origin. Much attention should be paid to the industrial values of high Se in this coal.