Study On The Mechanism Of Distributions And Occurrences Of Hazardous Minor And Trace Elements In Coal And Leaching Experiments Of Coal Combustion Residues

From the points of view of geology, geochemistry, mineralogy, coal petrology, environment chemistry, distributions and occurrences of 45 minor and trace elements, especially 22 hazardous trace elements, in 137 Chinese coals have been studied, and compared with those of U. S. A. coals and world-wild average value. Distributions of minor and trace elements in coal from different coal-accumulating eras were compared for the first time. The author studied distributions and occurrences of minor and trace elements in Permo-carboniferous coals from Shanxi province, and analyzed the leading factors which controlled the concentrations of minor and trace elements. The occurrence and distribution of minor and trace elements in No. 9-1 ,No .11 coal seams of Pingshuo opencut coal mine were investigated in detail. Genetic types of concentrations of minor and trace elements in coals for Chinese coals were proposed preliminary, for first time Distributions of minor and trace elements in vitrain and fusain from which mineral matter were removed by acids, and maceral groups which were separated through the density centrifuge were explored. The occurrences of trace elements in coals, especially Cr, Ni and Co, of which the level of confidence of the occurrence is low, were researched directly and quantitatively using sequential chemical extract of six steps. Leachability of 12 hazardous trace elements in coal combustion residuals under different pH value during 80 hours were observed, and the effects of occurrence of trace elements on leachability were discussed. For the first time, non-crystalline As were found in high arsenic coal from Guizhou province, of which arsenic contents is 3.2%, in which any arsenic-bearing minerals were not detected. Methods of determining different states of chlorine were established, and applied to the study on coals from Pingshuo opencut coal mine. Distributions of chlorine in macerals were also determined by SEM-EDX.