Yang, and six co-authors, reported in 2018 that they investigated the mineralogical and geochemical compositions of the upper Pennsylvanian coal from Hedong Coalï¬eld, in the eastern Ordos basin, China, using SEM, XRD, ICP-MS, ICP-CCT-MS, DMA-80 and ISE methods. The bituminous coal samples were collected form Nos. 3 and 4 Coal, which had low ash yield and were medium volatile, and had low sulfur content and low hazardous trace elements concentrations (Be, F, As, Hg, U and Pb). Maceral compositions were dominated by vitrinite (up to 90.2%), and to a lesser extent by inertinite and liptinite, all subgroups were detected in the coal samples. Minerals included quartz, clay minerals, sulï¬de and other oxide minerals.
SiO2 and Al2O3 were the dominant major elements-oxides in both coal seams with much higher concentrations than in Chinese coal, while other major elements-oxides (Na2O, K2O, Fe2O3, MgO) had average values compared to Chinese coal. No. 3 Coal was enriched in Li and Zr, and No. 4 Coal was enriched in Li, Be, Cu, Se, and In. Elemental occurrence was studied using statistical methods, and Li, Rb, Zr, Cs, Ba, Hf, Tl, Pb, and Th were inorganic affinities, while F, V, Cr, Ga, Ni, As, In, Ta occurred as inorganic–organic affinities and Fe and S may have occurred in pyrite. Coal facies indicators (GI, TPI, GWI, and VI) plots suggested that the two coal seams were deposited in different environments: No. 3 Coal was deposited in a wet forest swamp, while No. 4 Coal was formed in a mesotrophic (having a moderate amount of plants) to ombrotrophic (receiving all water and nutrients from precipitation, rather than from streams or springs. environment). The geochemistry of these coal samples (Al2O3/TiO2, TiO2/Zr, Zr/Sc and Th/Sc ratios) indicated that the coal samples sediment was sourced from intermediate and felsic igneous rocks.
The authors concluded that the Nos. 3 and 4 Coal samples were classiï¬ed as low ash yield (0.26–20.7%), low moisture (0.53–0.72%), medium volatile (10.93–37.88%) bituminous coal with low sulfur contents (0.30–0.59%). Vitrinite was the dominant maceral group with concentration up to 90.2% and lower proportion in No.3 Coal than in No.4 Coal. Inertinite content in No.3 Coal was higher than that of No.4 Coal.
Nearly all subgroups were detected in coal samples. Major minerals in both coal seams included quartz, clay minerals, sulï¬de and other oxide minerals. Major elements in coal samples were dominated by SiO2 (average on 49.83%) and Al2O3 (38.98%), whose average concentrations were much higher than other coals in China (8.47%, 5.98%); these occurred in quartz and clay minerals. Other major elements (Na2O, K2O, Fe2O3, and MgO) had average values compared to Chinese coal and may have occurred in sulï¬des based on their correlations with sulfur content. Compared to Chinese coal, No.3 Coal was enriched in Li and Zr, and No.4 Coal was enriched in Li, Be, Cu, Se, and In.
Correlation coefficients between elements and ash yield suggested that Li, Rb, Zr, Cs, Ba, Hf, Tl, Pb,and Th occurred in inorganic affinities, while F, V, Cr, Ga, Ni, As, In, and Ta had inorganic–organic affinities, and Fe and S may have occurred in pyrite. The REY concentrations ranged from 43.6 to 241.4 mg/kg in the coal samples with negative Eu anomalies. Based on the macerals compositions, coal facies indicators (GI, TPI, GWI, and VI) suggested that No. 3 Coal was deposited in a wet forest swamp and No. 4 Coal was formed from telmatic peat (developing in an environment with high tree density), in a mesotrophic to ombrotrophic environment. Elemental indicators, such as the ratios of Al2O3/TiO2, TiO2/Zr, Zr/Sc and Th/Sc, indicated that the studied coal sediments were likely derived from intermediate and felsic igneous rocks.
Managed & Built by I2M Consulting, LLC | © 2010-
