Occurrence of uranium in Chinese coals and its emissions from coal-fired power plants

Uranium is a trace elemental in coal. The uranium content from coal mines in China and its distribution in coal-fired power plant effluents was studied and reported in this paper. Chinese coal samples from eighteen coal mines were collected and analyzed for uranium. It was found that the uranium content for most of the coals was in the range from 1 to 3 mg/kg. Laboratory experiments with a tubular furnace indicate that the amount of uranium released from heated coal increases with temperature and with the retention time, when it combust. Most of the uranium (about 90%) in the coal can be transferred to the ash. Full-scale field tests were carried out at a coal-fired power plant to investigate the uranium distribution (and mass balance) in the coal, limestone, fly ash, bottom ash, gypsum and the flue gas. Almost all the uranium in the coal concentrated in the fly ash (about 80%) and the bottom ash (about 10%). The uranium content in the flue gas was less than 1/1000 of the total elemental input, between 0.043 and 0.069 mu g/m(3), which is much lower than the typical concentration of mercury or arsenic in flue gas of coal-fired power plant. The uranium content in the desulfurization gypsum product was found to be slightly larger than the uranium content of the limestone. (C) 2015 Elsevier Ltd. All rights reserved.