The Research Of Content Distribution And Occurrence Form Of Fluorine Element In Coals From Nantong Coalfield In Chongqing,China

In order to investigate the contents and the modes of occurrence of fluorine in coals from Nantong coalfield,and to provide scientific basis for rational exploitation and utilization of the coal resources in this area,38 samples were collected.It is 18 samples from No.4 coal-bed and 11 samples from No.6 coal-bed in Donglin mine,9 samples from No.5 coal-bed in Nantong mine.The general characteristics of fluorine contents, enrichment, distribution and modes of occurrence of fluorine were measured by various methods.Nantong coalfield is low volatile bituminous coal. XRD results show that there are mainly composed of clay minerals in coal and large amounts of pyrite in No.4 seam of Donglin mine and No.5 seam of Nantong mine, lead to higher levels of sulfur content in coal.The fluorine contents in the roof and floor are significantly higher than the content of fluorine in coal,especially the content of the roof in No.6 seam of Donglin mine is 8 times of the sample average in coal. The average concentration in No.4 seam is close to No.6 seam in Donglin mine,but significantly lower than the No.5 seam in Nantong mine.The average contents of Nantong coalfield is 490?g/g,is higher than the Songzao mine, the Changhebian mine,the southwest China (Chongqing, Guizhou, Yunnan and Sichuan), China and America. The content of fluorine in Donglin mine is higher than Nantong mine. The trends of content of three main coal seams are similar. It is higher for fluorine content in the roof and floor than coal in the No.4 seam,and higher than coal in the roof of the No.5 seam.The modes of occurrence of fluorine in the coals from Nantong coalfield were studied by ways of correlation analysis, factor analysis and hierarchical cluster analysis.Analysis results show that fluorine in coals from the No.4 seam existed in the organic and inorganic mineral simultaneous.Fluorine in coals from the No.6 seam existed in the organic.Fluorine in coals from the No.5 seam existed in the inorganic mineral (smectite and illite).