Fluorine in Chinese coals

Three hundred and five coal samples were taken from the main coal mines of twenty-six provinces, autonomous regions, and municipalities of China. The method of pyrohydrolysis was applied to measure the fluorine content in the samples, which exhibit logarithmic normal frequency distributions. The range of fluorine content in dry coal varies from 26 to 1230 mg/kg with a geometric mean of 136 mg/kg. The fluorine content decreases gradually from sub-bituminous through bituminous coal to anthracite. However, such varying tendency of fluorine content is not due to the presence of organic fluorine in coal. The geological age also apparently has no effect on the fluorine content. Even though the fluorine content of most coals in China is not high, much more attention should be given to the fluoride pollution caused by improper (unvented) coal-burning and the widespread household use of high-fluoride coal-clay.