云贵川交界地氟病区煤系黏土

Keywords: the border area of Yunnan /Guizhou and Sichuan /fluorosis /clay-pyrite /acid sulfate

Abstract: A popular riff is that the prevalence of endemic fluorosis in the border area of Yunnan,Guizhou and Sichuan is associated with the clay for coal-combustion. The emerging study confirms that efflorescent clay of coal-bearing strata has a high concentration of fluorine and acid, thus intensifing the release of hydrogen fluoride in the combustion of coal-clay mixed fuel. This paper utilized, Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) to verify the typical pyrite particles in the coal sample, which are rich in positive and negative ions such as HSO4-, SO4-, FeSO4+ and FeO+ on the basis of observation of the relevant clay samples. The results revealed that the relevant clay-pyrite had been weathered and produced acids as a result of long-term natural exposure of the coal-bearing strata in the study area. At the same time, the experiment of hydrogen fluoride release proved that the acid in the weathered soil enhanced the release of fluorine in the clay. Besides that, this paper also demonstrates the crucial role that TOF-SIMS should play in the study of natural minerals and their weathering.