Yanheng Li

Geochemical evidences of natural gas migration and releasing in the Ordos Basin, China

Natural gas, in its migration from source rocks to release zones may travel a long distance and change the geochemical characteristics of the rocks which it flowed through. In order to study the geochemical evidence of the natural gas migration, 24 samples were taken from different natural gas migration zones in the Ordos Basin, China. Five samples of them are from natural gas release zones (dark sandstone samples), 17 samples are from bleaching zones (bleaching sandstone samples), and two samples are from non-release zones (background samples). These samples were analyzed by organic and inorganic geochemical methods. The results of GC traces and ICP-MASS indicate that three zones show different organic and inorganic geochemical characteristics. Natural gas migration and releasing may be recognized by the geochemical evidences.

Li Distribution and Mode of Occurrences in Li-Bearing Coal Seam # 6 from the Guanbanwusu Mine, Inner Mongolia, Northern China:

Thirty-six coal bench samples from Coal Seam 6 and 13 parting samples from 5 parting layers were taken from the Guanbanwusu Coal Mine, Jungar Coalfield, Inner Mongolia, and the samples were analysed by optical microscopy, A scanning electron microscope in conjunction with an energy-dispersive X-ray spectrometer (SEM-EDX) analysis, X-ray powder diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence spectrometric (XRF) techniques. The results indicate that the average Li content are 264 ppm in coal and 1320 ppm or 0.28% Li2O in coal ash, indicating a Li ore deposit in coal. XRD analysis indicates that the minerals are kaolinite, boehmite, chlorite-group mineral, quartz, calcite, pyrite, siderite and amorphous clay material. The absorbed Li phases by kaolinite, boehmite and chlorite could be the most likely host model. Li could also be migrated into the peat by isomorphic impurity in chlorite. However, this migration form should not be the main form because chlorite contents are relative low. The total Li reserves reach to 24288 tons, that is, 52045 ton Li2O in this mine. The Yinshan Oldland chould be the most possible source of Li of the coal. The bauxite of the Benxi formation could be another source of Li of the coal in the NE Jungar Coalfield. The bauxite in the NE Jungar Coalfield was originally derived from the Yinshan Oldland.

Concentration of gallium in the Permo-Carboniferous coals of China

Gallium is widely used in electronic industry and its current price is about 500 US dollars pro kilogram. It has been found that its contents are very high in Permo-Carboniferous coal of China. In order to look for valuable associated gallium deposits in coal, gallium contents of 177 coal samples were determined by using inductively coupled plasma-mass spectrometry (ICP-MS) and the data of 873 coal samples from Chinese Permo-Carboniferous coalfields were collected. The results show that the average gallium concentration of Chinese Permo-Carboniferous coals is 15.49μg·g−1. There are two concentration types of gallium in Chinese Permo-Carboniferous coals: One type is that gallium has enriched to an ore deposit, and another type is that gallium is locally enriched in coal seams, but has not formed a valuable associated gallium ore deposit. The gallium concentration in Chinese Permo-Carboniferous coal may have several different sources: concentration in sedimentation stage, magmatic hydrothermal inputs and low-temperature hydrothermal fluids.

Concentrations of Lithium in Chinese Coals

Lithium is an important energy metal. Its concentrations in coals have been studied by many geologists. Its average content is only 14 mg/kg in the coals of the world. Lithium has never been reported as a coal associated deposit before. In order to study the concentrations in Chinese coals, 159 coal and gangue samples were taken from six coal mines and were determined by ICP-MS and the minerals in the samples were identified by X-ray powder diffraction. The results indicate that the Li contents in the coal samples from the Antaibao Coal Mine have reached the industry grade of coal associated deposits. In Tongxing Coal Mine, Li contents in the coal floor rock samples have reached the industry grade of independent lithium deposits. Main minerals are polylithionite, triphylite, zinnwaldite, lithionite and cookeite, which were transported into the peats. Therefore, lithium enriched most likely in the synsedimentary stage in both coal mines. Furthermore, a revised average Li content in Chinese coals was given.

Review of coal as a promising source of lithium

Coals are a major source of pollution in certain parts of the world due to mining, coal combustion, and disposal of fly ash. The recovery of valuable rare metals from coals or coal-processing byproducts is a promising way to utilise these traditional resources economically, efficiently and in an environmentally friendly way. Lithium, a highly interesting metal, has been found dispersed and even anomalously enriched in coal deposits, and is potentially extractable. This paper presents a review of geochemical investigations on Li-bearing coal and the technical development of Li extraction from coal. Based on available literature, inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma as an excitation source (ICP-AES) are regarded as the preferred methods of measuring Li concentration in coal and coal ash. Anomalous Li accumulations have been reported in coal deposits, especially in China. The limited studies on Li modes of occurrence and origins are discussed, and Li is shown to have an affinity mainly for clay minerals in coal, although further investigations are needed. Lithium is also found to be enriched in fly and bottom ashes during coal combustion. Finally, two successful Li recovery techniques from coal ash are presented.

Rare Earth Elements in No. 2 Coal of Huangling Mine, Huanglong Coalfield, China

Rare earth elements (REEs) can provide lots of information relevant to the evolution of source rocks, depositional environment, and epigenetic tectonic activity. In this study, 14 bench samples (including 11 coals, 1parting, 1roof and 1floor) of the No. 2 coal seam from Huangling Mine, Huanglong Coalfield, Ordos Basin, China were collected to study the REE geochemistry. The average concentration of REEs is 44.03 μg/g, and it is lower than those in coals of the Chinese and world coal. The coals are enriched in light REEs and the LREEs-HREEs have been highly fractionated, with an average (La/Yb) N of 11.38. The values of Ce/Ce* are more or less than 1 (with an average 0.92) and indicates that the anomaly of Ce is very slight. However, the values of Eu/Eu* (with an average 7.69 of coal) are distinctly higher than reported data of coals. The extremely high contents of Ba caused the geochemical anomaly of REEs. The Ba2+ was origin from the barium metallogenic belt in Qinling Old-upland.

Influences of coal mining water irrigation on the maize losses in the Xingdong Mine area, China.

In 2008, a maize underproduction disaster occurred in the Xianyu village after irrigation using the coal mining water from the Xingdong Mine, China. This disaster resulted in about 40 hectare maize underproduction and 20 hectare total loss of the maize yields. In order to study the reason, a total of 25 soil, water and plant samples were taken from the study area. These samples were analysed by inductively coupled plasma mass spectrometry and ion chromatography. The results indicate that the contents of both water-soluble fluorine and total fluorine are very high and resulting of maize underproduction and total loss of production. The possible pollution sources of fluorine in the study area could be from the coal mine water used for irrigation and glass chemical factory near the study area.

Organic Geochemical Characteristics of the No. 9 Coal (Pennsylvanian) from the Anjialing Mine, Ningwu Coalfield, China

Eight coal samples of Seam 9 were taken from the Anjialing Mine, Ningwu Coalfield, Shanxi Province, and were analysed by organic geochemical methods. The results indicate that the peat of Carboniferous Seam 9 may be formed dominantly in the marine-delta transition environments. The precursors of Seam 9 are both low and high plants existed in this basin.

Organic geochemistry of the Late Permian coals from the Huoshaopu and Jinjia Mines, Liupanshui Coalfield, China

Four coal samples from the Huoshaopu Mine and six coal samples from the Jinjia Mine, Liupanshui Coalfield, China were collected and analyzed, focusing on their petrological and organic geochemical features. The microscopic results show that the vitrinite random reflectance (Ro) of all samples is 0.97%, which is classified as high-volatile A bituminous coal. The maceral groups are dominated by vitrinite followed by inertinite. The low ratios (0.07–0.42) of saturated to aromatic hydrocarbons indicate a terrestrial plant input for the coals. Gas chromatography and gas chromatography/mass spectrometry were employed to analyze the composition of organic matter in the samples. The gas chromatography chromatograms of saturates display a monomodal outline of n-alkanes with a predominance of short chains. The odd-even preference values around 1 reflect the thermal maturity of the coals. Based on the different pristine/phytane ratios and dibenzofuran contents, we infer a relatively weak oxic coal-forming environment for Huoshaopu coals and a relatively anoxic environment for Jinjia coals. Among the aromatics, thermodynamically stable compounds, including 2-methylnaphthalene, 2,6 + 2,7-dimethylnaphthalenes, 3 and 4-methylbiphenyls, 4,4′-dimethylbiphenyl, methylphenanthrene, 2 and 3-methyldibenzofurans, were the dominant isomers in the respective homologs. The occurrence of dibenzothiophenes and benzonaphthothiophenes may confirm the paralic depositional environment of Late Permian coals from the Huoshaopu and Jinjia mines.