GEOCHEMISTRY OF PERMIAN COAL AND ITS COMBUSTION RESIDUES FROM HUAINAN COALFIELD

An INAA (instrumental neutron activation analysis) technique was applied to determine the abundance of rare-earth elements in 11 Permian coals from Huainan coalfield. The geochemistry of the combustion residues is analyzed by XRFS (X-ray fluorescence spectrometry), and the chemical compositions of some fly and bottom ashes are studied with the help of electronic probe. Compared with the coal in the world, most of the trace elements in Huainan coal are normally concentrated. Like the other coal in the world, the elements Se, S, As, Sb, Br, U and Cl are enriched in coal compared with Clark's value, while the other elements tend to be scattered in coal but fluctuate greatly and demonstrate great difference in different coal beds. On the other hand, the elements have a very similar abundant level in different bottom and fly ash samples. It is found that the elements with low organic affinity tend to concentrate in fly and bottom ash, and in particular, the elements with similar character of iron have 2 to 10 times concentration than in coal, meanwhile, the elements with strong organic affinity tend to dispose into the air. Moreover, the abundance of element in ash changes with different density and different density leads to different particle sizes. The bottom and fly ash consist of glass, lime, mullite, coal residues and ferrite minerals. Some carbon residues with sieve structure contain more elements of S, P, Cl and As, which indicates that the ash containing more carbon residues has a strong adsorptive power for some hazard elements in water. Hence, the study of the ash composition will make it possible to use ash by water cleaning and thus help the environment protection.