Hazardous trace elements in Jurassic coal from Ordos basin, China

摘要

Dongsheng Coalfield lies in the northern part of Ordos basin and near its margin. The main coal-bearingmeasure in this coalfield is Yan’an formation deposited in continental environment of middle -lowerJurassic. The coal from this coal-bearing measure are caking coal or long flame coal with 5%-9%average ash, less than 0.7% average total sulfur. Therefore these coals have good quality. In this paper,the hazardous elements such as Cu, Pb, Zn, Cd, Hg, Ni, V, and Mn in these coals were determined usingatomic absorption spectroscopy (AAS), atomic fluorescence spectroscopy (AFS) and polarography andvisible light spectrophotometric methods after coal samples were treated with chemical method. The datafor these trace elements in coals show that average concentrations of Cu, Pb , Zn, Ni, Cr, Cd, Hg and V inJurassic coal of Dongsheng Coalfield are very low, and is 0.11, 0.03, 0.23, 0.34, 0.11, 0.02, 0.01, 0.11times of that in whole Chinese coal. However, the content of Mn is 2.34 times higher than that of wholeChinese coal. The pyrite and other sulfur-bearing minerals are very small, main minerals are clayminerals (with average 4.87% SiO_2 and 0.61% Al_2O_3). Hence, distribution characteristics of mineral incoals lead to low concentrations of above hazardous trace elements, especially the chalcophile elements.