Trace Elements And The Environmental Significance In Coals From The East Of Huainan Coalfield

Coal in the Huainan coalfield has been, and continues to be, a valuable energy resource, especially for the electric utility industry. In recent years, the government has placed stringent demand (including environmental trace elements) on the coal that can be burnt in an environmentally acceptable manner. However, the research of environmental trace elements (ETEs) in coal from Huainan coalfield is not enough. Therefore, a greater understanding of the concentration, distribution, modes of occurrence of ETEs in coal from Huainan coalfield is critical if the Huainan coalfield is to continue to be a major producer of high-quality coal.Thirty-seven coal samples were collected from Xiejiaji mine, Xinzhuangzi mine and Panji mine, which located in the east of Huainan coalfield. The concentration of 22 kinds of ETEs in the samples was determined by inductively coupled plasma mass spectrometry (ICP-MS) and instrumental neutron activation analysis (INAA). The ranges and average values of the ETEs are presented. Comparisons with world averages and crustal abundances (Clark values) show that the coals from the eastern Huainan coalfield are highly enriched in Ag, Se and Hg;Comparisons with the averages of the coal of Shanxi, North China, China and America show that the coals from the east of Huainan coalfield are enriched in Se, V, Cu, Cr, Ni, Sb and Ba. We should pay more attention to these ETEs in coals from the east of Huainan coalfield. In addition, the distribution characteristics of the ETEs in different coal seams and the vertical distribution characteristics of the ETEs in selected coal seam were studied. The results indicate that there are large variations of ETEs distribution due to geologic variability of the individual coal seam.The modes of occurrence of selected ETEs in the coals from the eastern Huainan coalfield were studied by ways of correlation analysis, factor analysis and hierarchical cluster analysis. Relations of ETEs in coal to ash yield and to selected major elements are complicated. The results indicate that, in the coal from the east of Huainan coalfield, Cr, Th, Ba, U are closely associated with minerals (principally clay minerals);Mn, Co, Ni, Mo, Zn, Sb, Be, Tl closely associated with the macerals, and V, Sn, Cu, Pb, Cd, Se possibly can be associated with both the minerals and the macerals.This paper described the significance of the trace elements in coals fromenvironmental aspects. Using the trace elements as evaluating index, the lustration class of coal from the eastern Huainan coalfield was evaluated from the ETEs aspects. The evaluation result shows that the coals from the eastern Huainan coalfield belong to sub-dirty coal, if any actions are not taken during the coal preparation and combustion, it will cause some untoward effects to the environment.At last, this paper put forward some suggestions according to the results of this work. The removal of varying proportions of the total of contents of Cr, Ba, V, Cu and Se in the coal can be carried out by beneficiation, often referred as coal cleaning. But the content of Be, Ni and Sb in the coal from the eastern Huainan coalfield can not be removed only by conventional beneficiation. So, a further study of the behavior of these ETEs during the process of coal combustion should be carried out so as to decrease its negative impact on the environment as soon as possible.