Geochemistry of Trace Elements in Coals from the Yueliangtian Mine, Western Guizhou, China: Abundances, Modes of Occurrence, and Potential Industrial Utilization

Abstract

This paper reports the geochemical compositions of coals and non-coal samples from a complete seam section in the Late Permian Longtan Formation from the Yueliangtian mine, western Guizhou, southwestern China. The abundances, modes of occurrence, and origin of elements and minerals in the Yueliangtian coal were investigated using optical microscopy, scanning electron microscopy with an energy dispersive X-ray spectrometer, X-ray powder diffraction, X-ray fluorescence spectrometry, and inductively coupled plasma mass spectrometry. The host rocks (roof and floor) and one parting sample of the coal seam have high TiO2 contents, which is in accordance with the high TiO2 content in the Emeishan basalt from the Kangdian Upland. The coal bench samples are rich in SiO2 (14.52%, whole-coal basis) compared with the average for the common Chinese coals, and the high SiO2 present in this study is consistent with the abundant quartz, which was mainly precipitated from siliceous solutions produced by weathering of the Emeishan basalt. Compared to the average values for world hard coals, the coal bench samples are enriched in V (77.0 μg/g), Cu (41.9 μg/g), Se (4.77 μg/g), Zr (93.8 μg/g), Hg (0.375 μg/g), and Pb (21.4 μg/g). In contrast to many other Permian coals from southwestern China, the transition elements, including Cr, Co, Ni, and Zn, are not enriched in the coal bench samples, possibly due to the input of the terrigenous materials with felsic and felsic-intermediate rock compositions. The highfield strength elements are relatively enriched not only in the parting samples but also in the adjacent coal bench samples, indicating that the partings were subjected to leaching by groundwater during the diagenetic process. Elements in coal, including B, Cr, Co, Zn, and Ni, are mainly associated with clay minerals, while As, Se, Sb, and Pb mainly occur in sulfide minerals (pyrite and marcasite). An intra-seam volcanic ash-derived tonstein layer identified in the coal is characterized by strong negative Eu anomaly in the Upper Continental Crust-normalized rare earth elements and Y distribution pattern, indicating the input of felsic or felsic-intermediate terrigenous materials.

Enrichment of Nb-Ta-Zr-W-Li in the Late Carboniferous Coals from the Weibei Coalfield, Shaanxi, North China

“…The majority of the coal and non-coal rocks in the Dongdong mine fall within the trachyandesite and trachyte fields, pointing to a felsic-intermediate sediment provenance, while those in the Jinhuashan coal mine are distributed in slightly broader areas, falling within the fields of trachyandesite, trachyte, as well as rhyodacite/dacite (Figure 8B), pointing to a felsic-dominated sediment provenance. Overall, the sediment provenance of the terrigenous materials in the Weibei coalfield was characterized by felsic to intermediate chemical composition.Energies 2020, 13, x FOR PEER REVIEW 12 of 28[16,22,49,50]. The majority of the coal and non-coal rocks in the Dongdong mine fall within the trachyandesite and trachyte fields, pointing to a felsic-intermediate sediment provenance, while those in the Jinhuashan coal mine are distributed in slightly broader areas, falling within the fields of trachyandesite, trachyte, as well as rhyodacite/dacite (Figure 8B), pointing to a felsic-dominated sediment provenance.…”

“…(B) Diagram showing Zr/TiO 2 vs. Nb/Y ratios using the magma source discrimination diagram ofWinchester and Floyd (1977) [48].The elevated Ta, Nb, Zr, Li, and Win the Weibei coals exhibit high correlations and similar vertical distributions with HTA yields, Al 2 O 3 and SiO 2 contents (Figures 9 and 10), which represent an obvious aluminosilicate affinity and imply the terrigenous origin of these elevated elements. The Zr/TiO 2 -Nb/Y plot was widely used as an auxiliary indicator to discriminate the provenance, classification and evolution of altered volcanic ashes and associated coal bearing sequences[16,22,49,50]. The majority of the coal and non-coal rocks in the Dongdong mine fall within the trachyandesite and trachyte fields, pointing to a felsic-intermediate sediment provenance, while those in the Jinhuashan coal mine are distributed in slightly broader areas, falling within the fields of trachyandesite, trachyte, as well as rhyodacite/dacite (Figure 8B), pointing to a felsic-dominated sediment provenance.…”

Mineralogical and Geochemical Compositions of the Lopingian Coals in the Zhongliangshan Coalfield, Southwestern China

“…Pyrite is a common mineral in the Lopingian coal seams in southwestern China [8,39,[42][43][44]. From the K1 to K10 coal LTA residues, the proportion of pyrite increases gradually, from 2.7% (K3-1) to 20.4% (K10-5) and with an average of 10.5%.…”

“…Chamosite is not usually observed in the coal, however, it does commonly occur in the Lopingian coals in southwestern China [39,40,42,45,49]. Two origins of chamosite have been proposed, which is either derived from the alteration of kaolinite by the injection of Fe-Mg-rich fluids during diagenesis process [40], or directly precipitated from hydrothermal fluids enriched Fe [49].…”

Fluorine in Chinese Coal: A Review of Distribution, Abundance, Modes of Occurrence, Genetic Factors and Environmental Effects

“…Most of it was adsorbed on minerals, and the rest was in solution or substituted in minerals structures. According to recent reports, most of the fluorine in coal was adsorbed [24,27,28,37,42,43]. Studies on Songzao coal from Chongqing found that F, together with Ga, Sn, U, Th, Zr, Hf, and Ta, had positive correlations with Al 2 O 3 , suggesting that fluorine occurred in clay minerals (kaolinite and others) [19,61].…”