Modes Of Occurrence And Environmental Effects Of Trace Elements In Coal From No.10 Coal-bed At Western Huagou, Guoyang

In order to investigate the modes of occurrence and environmental effects of trace elements in coal from No.10 coal-bed at western Huagou, and to provide scientific basis for rational exploitation and utilization of the coal resources in this area,10 coal samples were collected from the cores of different boreholes, the enrichment, modes of occurrence, and volatility of trace elements were measured by various methods. Finally, a three-graded clean degree assessment method of coal based on fussy comprehensive evaluation were discussed and applied in assessing the cleanliness of coal resources from No.10 coal-bed.The concentrations of 13 kind trace elements were determined using inductively coupled plasma mass spectrometry (ICP-MS). Most trace elements are of normal or low levels compared with its Clarkes in Northern China, Chinese and world coals. Trace elements are slightly enriched or non-enriched in major coal sample, which could be concluded from the enrichment factor related to their contents in the crust, and rock and soil of Chinese continent.Total organic carbon (TOC) of the coal was measured by LECO carbon and sulfur analyzer. The correlations between TOCs and concentrations of trace elements indicate that Beryllium, Ba, Zn, and Mo are associated with organic matter and minerals in coal, but Beryllium and Ba are mainly in minerals, however, Zinc and Mo are evenly distributed in organic and inorganic matter. Vanadium, Cr, Co, Ni, Cu, Sb, Pb and Tl have strongly inorganic affinity, while cadmium is on the contrary.Inorganic matters of No.10 coal are mainly consist of clay minerals such as kaolinite, and carbonate mineral siderite and calcite. Quartz, pyrite, muscovite and bixbyite are detected in individual coal samples by X-ray diffraction (XRD).Cluster analysis result demonstrates that eleven trace elements belong to adsorption species by alumino-silicate, or partially locate in carbonate minerals, Vanadium, Sb, Cu, Cr, Pb, Co, Ni, Tl, Mo, Be and Ba included. Zinc and Cd pertain to organic combination, and the latter mainly associated with organics.Factor analysis illustrates that all thirteen trace elements can be expressed by three factors, F1, F2 and F3, respectively. Vanadium, Cr, Co, Ni, Cu, Sb, Pb and Ba have large factor loading in F1. Beryllium, Tl and Mo are significant in F2. Zinc and Cd are important in F3. too. According to the modes of occurrence of trace elements, F1 can be designated as inorganic association factor or aluminosilicate factor, F3 may be named organic combination factor, nevertheless F2 is uncertain factor because the occurrence of the three trace elements aren't definitive as others.Trace elements in coal could be classified into three groups based on their volatilities in combustion process. Beryllium, Cr, Co, Ni, Cu, Zn, Sb and Ba moderately volatilize in combustion and uniformly distribute in bottom and fly ash. While Lead, Tl and Cd easily form vapor and escape the stack or pollution control devices as gaseous phase or aerosol. Thus, precaution and protective measures should be taken when utilize the coal from No.10 coal-bed at western Huagou owing to easy volatility and relatively high contents of Lead, Tl and Cd. The volatilities of Molybdenum and V are uncertain because experimental error.Choosing some parameters of raw coal including ash yields, sulfur contents, the contents, volatility and modes of occurrence of trace elements, and technical characteristics as evaluating index, and assigning the weight of the third evaluating indice according to the toxicity of trace elements, and then build a completed clean degree evaluation system for coal using fuzzy comprehensive evaluation method. At last, the evaluation system is applied in the assessment of cleanliness of coal from No.10 coal-bed at western Huagou, and the results show that the coal resources of No.10 coal-bed is clean and have little environmental effects and healthy implications.