The sedimentary characteristics and their combination succession of the Permian in the Shandong nd Huainan-Huaibei coalfields are analyzed. The mid-and short-term stratigraphic base-level cycles are identified. High-r...The sedimentary characteristics and their combination succession of the Permian in the Shandong nd Huainan-Huaibei coalfields are analyzed. The mid-and short-term stratigraphic base-level cycles are identified. High-resolution sequences are divided based on the above results. The study shows that the stratigraphic base-level cyclic method is an efficient way in the determination of the high-resolution sequences, especially in the classification of tbe terrestrial and transitional depositional succession.展开更多
In exploiting shallow coal resources in western China, conservation of water resources is often subjugated to considerations of safety and production in coal mines. In order to maintain a sustainable development in th...In exploiting shallow coal resources in western China, conservation of water resources is often subjugated to considerations of safety and production in coal mines. In order to maintain a sustainable development in the Shenfu-Dongsheng coalfield, we propose a technology of constructing groundwater reservoirs in goafs in shallow coalfields to protect fragile ecological environments. Given the premise of safe production, we selected an appropriate goaf as the site for constructing a groundwater reservoir and used a mine water recharge technique in combination with other related techniques for effective water conservation. Then filtering and purification techniques were used to purify the mine water given the physical and chemical properties of mine water and its filling material, ,thereby greatly reducing suspended matter, calcium and other harmful ions in the water. With the potential of widely application, the research result has been successfully applied in the Daliuta coal mine, to great economic and ecological effect. Therefore, this achievement provides a new way for mine water conservation in shallow coal resources in western China.展开更多
With the identification of coal deposits that are enriched in rare earth elements(REEs)across the world,coal and coal by-products are considered as an alternative source for REEs due to the combined supply and demand ...With the identification of coal deposits that are enriched in rare earth elements(REEs)across the world,coal and coal by-products are considered as an alternative source for REEs due to the combined supply and demand restrictions for these elements.Studies are being conducted to recover these elements from various coal sources.In this study,coal samples from the East Kootenay coalfields in British Columbia,Canada were examined for the presence of REEs in run-of-mine coal samples and flotation products.Results reveal that on an ash basis,the concentration of REEs varies from 174 to 1038 mg/kg in the samples.To understand the REE as sociation,which is essential for extraction purposes,a three-step sequential extraction process along with a mineralogical evaluation using scanning electron microscopy(SEM)with energy dispersive X-ray spectroscopy(EDX)and quantitative X-ray diffraction(XRD)data was used.It is found that a significant portion of REEs in the feed samples were reported to middling and tailings streams.The mineralogical analyses reveal REE association with aluminosilicate mineral in the samples.展开更多
Africa is host to coal deposits stretching from the far north to the far south and ranging in age from the Carboniferous through to the Miocene.Coal production in the north of the continent is however currently of a v...Africa is host to coal deposits stretching from the far north to the far south and ranging in age from the Carboniferous through to the Miocene.Coal production in the north of the continent is however currently of a very limited nature compared to that in the south,where due mainly to its low cost and relative abundance,the commodity has long been the primary source of energy.Coal is also used extensively in the metallurgical(titanium,ferrochrome,ferromanganese and steel)industries.All of the main exploited coal deposits in South-Central Africa are hosted in sedimentary rocks of the Late Carboniferous to Middle Jurassic aged,Karoo Supergroup and their temporal equivalents.展开更多
The geothermal history and the tectonic subsidence history of the Huaibei-Huainan coalfields were reconstructed by using the vitrinite reflectance data, and their correlative restriction on coalbed gas generation of H...The geothermal history and the tectonic subsidence history of the Huaibei-Huainan coalfields were reconstructed by using the vitrinite reflectance data, and their correlative restriction on coalbed gas generation of Huaibei-Huainan coalfields and Qinshui coal basin was discussed. The burial, thermal, and maturity histories of are similar between Huaibei coalfield and Huainan coalfield, obviously different from those of Qinshui coal basin. Based on the tectono-thermal evolution characters of Huaibei-Huainan coalfields and Qinshui basin, the process of coalbed gas generation can be divided into three stages： （1） Dur- ing Early Mesozoic, both in Huaibei-Huainan and Qinshui, the buried depth of Permian coal seams increased rapidly, which resulted in strong metamorphism and high burial temperature of coal seams. At this stage, the coal rank was mainly fat coal, and locally reached coking coal. These created an environment favoring the generation of thermogenic gas. （2） From Late Ju- rassic to Cretaceous, in the areas of Huaibei-Hualnan, the strata suffered from erosion and the crust became thinning, and the Permian coal-bearing strata were uplifted to surface. At this stage, the thermogenic gas mostly escaped. Conversely, in Qinshui basin, the cover strata of coal seams kept intact during this stage, and the thermogenic gas were mostly preserved. Furthermore, with the interaction of magmatism, the burial temperature of coal seams reached higher peak value, and it was suitable for the secondary generation of thermogenic gas. （3） From Paleogene onward, in area of Huainan-Huaibei, the maturity of coal and burial temperature were propitious to the generation of secondary biogenic gases. However, in Qinshui basin, the maturity of coal went against genesis of second biogenic gas or thermogenic gas. By comparison, Huaibei-Huainan coalfields are dominated by thermogenic gas with a significant biogenic gas and hydrodynamic overprint, whereas Qinshui basin is dominated mainly by thermogenic gas.展开更多
This study investigates the paleodepositional conditions of the No.6 Seam of the Madzaringwe Formation in Makhado and Voorburg south area of the Soutpansberg Coalfield(Limpopo Province,South Africa)utilizing organic p...This study investigates the paleodepositional conditions of the No.6 Seam of the Madzaringwe Formation in Makhado and Voorburg south area of the Soutpansberg Coalfield(Limpopo Province,South Africa)utilizing organic petrography and inorganic geochemical proxies.The coals are predominantly high-volatile bituminous B-A rank with high ash yields(avg.36.1 wt%),characterized by high-vitrinite(~41.5 vol%),moderate-to-high inertinite(9.8 vol%–33.7 vol%)and low liptinite(~2.3 vol%).The distribution of inertinite varies among different coal horizons(from bottom-lower to middle-upper),suggesting differential oxidation conditions and/or paleofire occurrence.Vitrinite-to-inertinite(V/I)ratio,tissue preservation–gelification index(TPI–GI),and groundwater–vegetation index(GWI–VI)plots,indicate that the peat-forming forest-swamp vegetation accumulated under mesotrophic-to-rheotrophic hydrological conditions.The presence of structured macerals(i.e.,telinite,collotelinite,fusinite,and semifusinite)suggests well-preserved plant tissues,whereas framboidal pyrite and sulphur content(0.24 wt%–2.16 wt%)point to brackish-water influence at the peat stage.The coals contain quartz,kaolinite,siderite,muscovite,dolomite,calcite,and pyrite minerals,most of which were likely sourced from felsic igneous rocks.The Al/(Al+Fe+Mn)and(Fe+Mn)/Ti ratios for the studied samples range between 0.24–0.97 and 0.57–70.10,respectively.The ratios,Al–Fe–Mn plot,and presence of massive botryoidal-type pyrite imply some influence of meteoric waters or fluids from hydrothermal activity post-deposition.Moreover,the chemical index of alteration(CIA:98.25–99.67),chemical index of weathering(CIW:92.04–97.66),and A–CN–K ternary diagram suggest inorganic matter suffered strong chemical weathering,indicating warm paleoclimatic conditions during the coal formation.展开更多
The karst groundwater of Cambrian limestone may become an important water source for industry and agriculture in the Pingdingshan area,and is also a potential threat to mining safety.Therefore,to find out the origin,f...The karst groundwater of Cambrian limestone may become an important water source for industry and agriculture in the Pingdingshan area,and is also a potential threat to mining safety.Therefore,to find out the origin,flow paths,and hydrogeochemical processes of karst groundwater beneath the Pingdingshan coalfield,a total of 16 water samples were collected.Our findings confirmed that the karst groundwater is mainly recharged by precipitation.The precipitation can directly supply the deep aquifer of the karst water system through the southwest limestone outcrops,and this area mostly includes the southern part of mines No.11,No.9,and the hidden outcrops in the southern part of mine No.2.What is more,the areas adjacent to the synclinal axis,including mines No.10,No.12,and No.8,may be the main discharge areas.A mixing model of^(87)Sr/^(86)Sr and Sr showed that in the southwest Pingdingshan coalfield,the proportion of precipitation decreased gradually from the recharge area to the discharge area,ranging from 89.1%to 17.1%.Besides,the northeast Pingdingshan coalfield is another recharge area for the whole karst system,thus,the infiltrating groundwater will indirectly supply the deep aquifer through Quaternary deposition near the mine No.13.Our research results can provide theoretical support for the prevention and control of groundwater disasters and the development and utilization of regional groundwater resources in the coalfield in Northern China.展开更多
Numerous coal fires burn underneath the Datong coalfield because of indiscriminate mining.Landsat TM/ETM,unmanned aerial vehicle（UAV）,and infrared thermal imager were employed to monitor underground coal fires in th...Numerous coal fires burn underneath the Datong coalfield because of indiscriminate mining.Landsat TM/ETM,unmanned aerial vehicle（UAV）,and infrared thermal imager were employed to monitor underground coal fires in the Majiliang mining area.The thermal field distributions of this area in 2000,2002,2006,2007,and 2009 were obtained using Landsat TM/ETM.The changes in the distribution were then analyzed to approximate the locations of the coal fires.Through UAV imagery employed at a very high resolution（0.2 m）,the texture information,linear features,and brightness of the ground fissures in the coal fire area were determined.All these data were combined to build a knowledge model of determining fissures and were used to support underground coal fire detection.An infrared thermal imager was used to map the thermal field distribution of areas where coal fire is serious.Results were analyzed to identify the hot spot trend and the depth of the burning point.展开更多
Coal oxidation at low temperatures is the heat source liable for the self-heating and spontaneous combustion of coal. This phenomenon has imposed severe problems in coal related industries. Attempts to understand this...Coal oxidation at low temperatures is the heat source liable for the self-heating and spontaneous combustion of coal. This phenomenon has imposed severe problems in coal related industries. Attempts to understand this phenomenon by previous researchers have provided significant progress. It is wellknown that coal oxidation at low temperatures involves oxygen consumption and formation of gaseous and solid oxidation products. This process is majorly influenced by temperature, oxidation history of coal,coal properties, particle size distribution of the coal, etc. The current understanding of the phenomenon of self-heating and spontaneous combustion of coal is discussed along with the different experimental and numerical models established to predict self-heating characteristics of coal. This paper focuses on the global position of the study carried out by academics, research institutes and industries on spontaneous combustion of coal and coal mine fires. Within this framework, the generally used spontaneous combustion techniques to predict the spontaneous combustion liability of coal were evaluated. These techniques are well-known in their usage, but no specific method has become a standard to predict the spontaneous combustion liability. Further study is still needed to indicate a number of impending issues and to obtain a more complete understanding on the phenomenon.展开更多
This study presents a review of the various methods to predict the spontaneous combustion liability of coal and coal-shale. The relative propensity of coal to undergo self-heating can be established by different metho...This study presents a review of the various methods to predict the spontaneous combustion liability of coal and coal-shale. The relative propensity of coal to undergo self-heating can be established by different methods. These methods are well established in their usage, but the fact that no particular test method has become a standard to predict the spontaneous combustion liability indicates that doubt still exists as to the validity of all of them. The underlying principle of all the tests is that the more readily the coal undergoes exothermic oxidation, the more liable it is to self-heat. Comprehensive studies that centres on the international position on research being conducted by academics, different research institutes and industries on spontaneous combustion of coal and coal mine fires were evaluated. Relationships between the geochemical analysis (proximate and ultimate analysis, forms of sulphur, petrographic properties, X-ray diffraction and X-ray fluorescence) and spontaneous combustion testing methods (numerical and experimental approaches) used to predict the spontaneous combustion liability of coal were reviewed. The combination of these tests provides a better understanding of the mechanism that controls the spontaneous combustion phenomena. However, irrespective of the extensive studies that have been conducted over time, spontaneous combustion is still a major problem in the coal value chain.展开更多
Total 138 coal samples and 14 parting samples were taken from the No. 6 Seam of the Jungar Coalfield, Inner Mongolia. These samples were analysed by optical microscopy, sequential chemical extraction procedure （SCEP...Total 138 coal samples and 14 parting samples were taken from the No. 6 Seam of the Jungar Coalfield, Inner Mongolia. These samples were analysed by optical microscopy, sequential chemical extraction procedure （SCEP）, inductively coupled plasma mass spectrometry （ICP-MS）, X-ray powder diffraction （XRD）, and scanning electron microscope in conjunction with an energy-dispersive X-ray spectrometer （SEM-EDX） analysis. The results indicate that the Li contents have reached the industrial grade of the coal associated Li deposit, and the total Li reserves have reached 2406600 tons, that is, 5157000 tons Li2O in the No. 6 seam in the Jungar Coalfield. The sequential chemical extraction procedure results suggest that the Li concentration is mainly related to inorganic matter. The minerals in the coals consist of kaolinite, boehmite, chlorite-group mineral, quartz, calcite, pyrite, siderite and amorphous clay material. Some Li could be absorbed by clay minerals in the Li-bearing coal seam. The chlorite phase？could be？most likely the host for a part of Li. The Yinshan Oldland should be the most possible source of Li of the coal.展开更多
This paper discussed the petrographic characteristics of No.6 coal from the Xiaoyugou mine,Jungar Coalfield,Ordos Basin,China.10 samples(7 coal,1 parting mudstone and 2 floor mudstone)were analysed by microscopical an...This paper discussed the petrographic characteristics of No.6 coal from the Xiaoyugou mine,Jungar Coalfield,Ordos Basin,China.10 samples(7 coal,1 parting mudstone and 2 floor mudstone)were analysed by microscopical and geochemical methods.Four maceral compositions and several associated elements parameters were selected as indicators and corresponding diagrams were drawn to explicate the sedimentary environment.The results indicate that the maceral is dominated by vitrinite and minerals are mainly kaolinite in the No.6 coal.The sedimentary facies vary from barrier island system to tidal-flat which is a deposition process of water body shallowing and the coal-forming plants are herbs and woody plants formed in swamps.展开更多
Based on the systematic analysis of the coal gangue in Weibei Coalfield, such as petrologic characteristics, chemical composition, nutrient elements, deleterious elements, and the transformation, and compared with the...Based on the systematic analysis of the coal gangue in Weibei Coalfield, such as petrologic characteristics, chemical composition, nutrient elements, deleterious elements, and the transformation, and compared with the soil element content background values of Loess Plateau and national harmful materials controlling standards, we conclude that the coal gangue in the Weibei Coalfield has huge potential to be used as clay fertilizer.展开更多
Santanghu Coalfield is the largest integrated coalfield exploration area in China. The major coal seams developing in Xishanyao Formation (Middle Jurassic) are the high-quality steam coals characterized by large thick...Santanghu Coalfield is the largest integrated coalfield exploration area in China. The major coal seams developing in Xishanyao Formation (Middle Jurassic) are the high-quality steam coals characterized by large thickness, favorable horizontal continuity and high coal quality. In this paper, twenty-two samples were collected from the three typical boreholes in Hanshuiquan disirict, representing the 11 coal seam sequences (7#,8#,9#,13#, 14#,15#,17#,18#,19#,20#,22#), respectively. The petrographic characteristics of the coal-bearing sequence in Xishanyao Formation were firstly summarized systematicly, and then the coal-forming swamp characteristics and succession mechanism of the coal seam in Xishanyao Formation were defined by analyzing the samples. The maceral composition, structure, geochemical and geophysical characteristics of coal are in eluded in original genetic criteria of coal-forming swamp an alysis. And the composition of coal petrography, maceral and microlithotype are the most frequently used parameters. Coal is composed of microscopic constituents and inorganic substances. The Xishanyao Formation maceral mainly consists of vitrinite (65.74%-97.01 %), inert i nite (1.93%-34%), and the exinite shows the mode of regular change. The coal-forming swamp in Xishanyao Formation possesses the characteristics of mainly marsh, wet forest swamp facies, and shallow water covered forest swamp facies, and a few of coal seams distribute in the deep water covered forest swamp facies. In addition, the sporopollens in Xishanyao Formation are mainly Pinaceae evergreen broad leaf and needle-leaved plants. Osmundaceae, Cyatheaceae and Lygodiaceae, indicating that the warm and humid tropic-subtropical climate conductive to the persistent growth of coal-forming plants in the Middle Jurassic. The coal-forming swamp shows the characteristics of vertically upward fluctuation through the periodic transition. It indicates a shallow-deep-shallow change process of the water covered depth in the swamp. This is the prin ci pal factor for the formation of the high-quality and continuous coal seam in Hanshuiquan district, Santanghu Coalfield.展开更多
Total of 23 bench samples were taken from the No. 7 Coal of Iqe Coalfield, Qinghai Province, China, following Chinese Standard Method GB/T 482-2008 （2008）. These samples were analyzed by powder X-ray diffraction （...Total of 23 bench samples were taken from the No. 7 Coal of Iqe Coalfield, Qinghai Province, China, following Chinese Standard Method GB/T 482-2008 （2008）. These samples were analyzed by powder X-ray diffraction （XRD）, inductively coupled plasma mass spectrometry （ICP- MS） and X-ray fluorescence （XRF）. The results indicate that the No. 7 Coal belongs to a low rank （Ro.ran =0.659%） and high-ash coal （40.54%）. Compared to common Chinese and world low-rank coals, the lqe coal contains anomalous concentrations of rare metal elements, rare-scattered （dispersed） elements and rare earth elements. The highest contents of Rb, Cs, Ga and REY reach to 180, 26, 37, and 397 ppm, respectively. Their average contents of these elements are 10.9, 15, 4.8 and 3.5 times higher than those of world coals, respectively. Minerals in the coal include kaolinite, quartz, muscovite, siderite, and traces of rutile, and brookite. Kaolinite could be main host minerals of Rb, Cs, Ga and REY. The anomalous rare element Rb and Cs accumulation in the Iqe coal is related to both organic and inorganic matter. The REY concentrations may be related to circulation of thermal solutions, contained or sorbed by clayey particles, and organic matter as well.展开更多
Coal and coal-shale undergo low-temperature oxidation when exposed to air,potentially leading to spontaneous combustion.Coal-shale found in association with coal seams vary considerably in their intrinsic properties a...Coal and coal-shale undergo low-temperature oxidation when exposed to air,potentially leading to spontaneous combustion.Coal-shale found in association with coal seams vary considerably in their intrinsic properties and spontaneous combustion liability index.Fourteen coal-shale samples collected from four different coal mines in Witbank Coalfield,South Africa,were experimentally investigated.The influence of coal-shale intrinsic properties and spontaneous combustion liability indices(determined by the WitsEhac Index and the Wits-CT Index)were established.The liability indices indicate relationships with the intrinsic factors and thus,identifying the major intrinsic factors affecting liability toward spontaneous combustion in these coal-shale samples.The XRF analysis indicated that the coal-shale samples are rich in Si O2,Al2O3 and Fe2O3,while the XRD showed that same coal-shale samples are generally dominated with kaolinite and quartz.The coal-shale occurred in association with medium Rank C bituminous coal and contained varying proportion of macerals.The Wits-Ehac Index was unable to reliably determine liability indices of some coal-shale samples,and hence the Wits-CT Index was developed.The results obtained from the characterisation tests may be used as a tool to predict the spontaneous combustion liability in carbonaceous material and may serve as a reference when comparing coal-shale from different coal mines.展开更多
Coal fire burning around the world is an environmental catastrophe characterized by the emission of noxious gases, particulate matter, and condensation by-products. In this study, coal fire temperature is retrieved ba...Coal fire burning around the world is an environmental catastrophe characterized by the emission of noxious gases, particulate matter, and condensation by-products. In this study, coal fire temperature is retrieved based on Landsat 5 TM images and Generalized Single-Channel Algorithm (GSCA), in Wuda coalfield, Inner Mongolia, China. Then coal fire zones are extracted by Jenks′ natural breaks and threshold methods based on temperature images. Changes of coal fire zones are analyzed from 1989 to 2008. The results are summarized as follows: 1) The coal fire temperature retrieval method based on Landsat 5 TM and the GSCA model is effective and feasible, because the temperature error is relatively small (from –2.9℃ to +2.6℃) between the measured temperature and the retrieved temperature. 2) The accuracy is relatively high to extract coal fire zones through the Jenks′ natural breaks and threshold methods, because 83.56% of surveyed area is located in the coal fire zones extracted in 2005. 3) The coal fire area increased 9.81 × 10 5 m 2 from 1989 to 2005, and the annual growth is about 6.1 × 10 4 m 2 , with an annual increasing rate of 2.48%. The area of coal fire decreased by 8.1 × 10 5 m 2 from 2005 to 2008.展开更多
Water flooding disasters are one of the five natural coal-mining disasters that threaten the lives of coal miners. The main causes of this flooding are water-conducting fractured zones within coal seams. However, when...Water flooding disasters are one of the five natural coal-mining disasters that threaten the lives of coal miners. The main causes of this flooding are water-conducting fractured zones within coal seams. However, when resistivity methods are used to detect water-conducting fractured zones in coal seams, incorrect conclusions can be drawn because of electrical anisotropy within the water-conducting fractured zones. We present, in this paper, a new geo-electrical model based on the geology of water-conducting fractured zones in coal seams. Factors that influence electrical anisotropy were analyzed, including formation water resistivity, porosity, fracture density, and fracture surface roughness, pressure, and dip angle. Numerical simulation was used to evaluate the proposed electrical method. The results demonstrate a closed relationship between the shape of apparent resistivity and the strike and dip of a fracture. Hence, the findings of this paper provide a practical resistivity method for coal-mining production.展开更多
The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone...The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone aquifers.Our study describes the mechanism of mine water inrushes through a fault in the mine floor using principles of strata mechanics and the path of water inrush from an aquifer to the working face.A criterion to judge whether a ground water inrush will occur through a fault or not is also described, together with a case history of water inflow in the Feicheng coalfield, China.展开更多
Heavy mining of Jurassic and Carboniferous horizontal coal seams in the Datong coalfield has seriously affected the local geological environment, which is mainly manifested by such geohazards as soil avalanches, lands...Heavy mining of Jurassic and Carboniferous horizontal coal seams in the Datong coalfield has seriously affected the local geological environment, which is mainly manifested by such geohazards as soil avalanches, landslides, mudflows, surface subsidence, surface cracks, surface solid waste accumulation and surface deformation. More seriously, coal mining causes groundwater to leak. Overpumping of groundwater has resulted in substantial land subsidence of the urban area in Datong City. Based on the previous geo-environmental investigation in the work area, the authors used radar remote sensing techniques such as InSAR （synthetic aperture radar interferometry） and D-InSAR （differential synthetic aperture radar interferometry）, supplemented by the optical remote sensing method, for geo-environmental investigation to ascertain the geo-environmental background of the Datong Jurassic and Carboniferous-Permian coalfield and evaluate the effects of the geohazards, thus providing a basis for the geo-environmental protection, geohazard control and prevention, land improvement and optimization of the human environment. In this study 8 cog-nominal ERS-1/2 SAR data frames during 1992 to 2003 were used, but the following processing was made： （1） the multitemporal SAR magnitude images were used to interpret the geological structure, vegetation, microgeomorphology and drainage system; （2） the multi-temporal InSAR coherent images were used to make a classification of surface features and evaluate the coherence change due to coal mining; and （3） the multi-temporal cog-nominal SAR images were used to complete D-InSAR processing to remove the information of differential deformation areas （sites）. In the end, a ten-year time series of differential interferograms were obtained using the multi-temporal cog-nominal SAR images. In the tests, 84 deformed areas （sites） were obtained, belonging to those in 1993-1996, 1996-1997, 1997-1998, 1998-2001, 1998-2002 and 2001-2003 respectively. Of the 84 areas, 44 are mining subsidence ones, 23 urban subsidence ones and 17 landslide subsidence ones. They cover a total area of 1824.4 km^2, equivalent to the area of the whole Datong coalfield. Then an accurate evaluation was made on the geo-environment of the Datong coalfield. The tests show that InSAR is now the only feasible technical means for making one all-weather, real-time measurement of a coal mining land subsidence area covering up to 10,000 km^2 to subcentimeter resolution. This study is a successful application of InSAR in the investigation and evaluation of land subsidence, especially in coal mining areas.展开更多
文摘The sedimentary characteristics and their combination succession of the Permian in the Shandong nd Huainan-Huaibei coalfields are analyzed. The mid-and short-term stratigraphic base-level cycles are identified. High-resolution sequences are divided based on the above results. The study shows that the stratigraphic base-level cyclic method is an efficient way in the determination of the high-resolution sequences, especially in the classification of tbe terrestrial and transitional depositional succession.
基金Projects NCET-05-0480 supported by the New Century Excellent Talents in University50904063 by the National Natural Science Foundation of China+1 种基金07KF09 by the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety of China University of Mining & Technology2008A003 and 2005B002 by the Scientific Research Foundation of China University of Mining & Technology
文摘In exploiting shallow coal resources in western China, conservation of water resources is often subjugated to considerations of safety and production in coal mines. In order to maintain a sustainable development in the Shenfu-Dongsheng coalfield, we propose a technology of constructing groundwater reservoirs in goafs in shallow coalfields to protect fragile ecological environments. Given the premise of safe production, we selected an appropriate goaf as the site for constructing a groundwater reservoir and used a mine water recharge technique in combination with other related techniques for effective water conservation. Then filtering and purification techniques were used to purify the mine water given the physical and chemical properties of mine water and its filling material, ,thereby greatly reducing suspended matter, calcium and other harmful ions in the water. With the potential of widely application, the research result has been successfully applied in the Daliuta coal mine, to great economic and ecological effect. Therefore, this achievement provides a new way for mine water conservation in shallow coal resources in western China.
文摘With the identification of coal deposits that are enriched in rare earth elements(REEs)across the world,coal and coal by-products are considered as an alternative source for REEs due to the combined supply and demand restrictions for these elements.Studies are being conducted to recover these elements from various coal sources.In this study,coal samples from the East Kootenay coalfields in British Columbia,Canada were examined for the presence of REEs in run-of-mine coal samples and flotation products.Results reveal that on an ash basis,the concentration of REEs varies from 174 to 1038 mg/kg in the samples.To understand the REE as sociation,which is essential for extraction purposes,a three-step sequential extraction process along with a mineralogical evaluation using scanning electron microscopy(SEM)with energy dispersive X-ray spectroscopy(EDX)and quantitative X-ray diffraction(XRD)data was used.It is found that a significant portion of REEs in the feed samples were reported to middling and tailings streams.The mineralogical analyses reveal REE association with aluminosilicate mineral in the samples.
文摘Africa is host to coal deposits stretching from the far north to the far south and ranging in age from the Carboniferous through to the Miocene.Coal production in the north of the continent is however currently of a very limited nature compared to that in the south,where due mainly to its low cost and relative abundance,the commodity has long been the primary source of energy.Coal is also used extensively in the metallurgical(titanium,ferrochrome,ferromanganese and steel)industries.All of the main exploited coal deposits in South-Central Africa are hosted in sedimentary rocks of the Late Carboniferous to Middle Jurassic aged,Karoo Supergroup and their temporal equivalents.
基金supported by National Natural Science Foundation of China (Grant Nos. 41030422, 40772135, 40972131, 40940014)National Basic Research Program of China (Grant No. 2009CB219601)
文摘The geothermal history and the tectonic subsidence history of the Huaibei-Huainan coalfields were reconstructed by using the vitrinite reflectance data, and their correlative restriction on coalbed gas generation of Huaibei-Huainan coalfields and Qinshui coal basin was discussed. The burial, thermal, and maturity histories of are similar between Huaibei coalfield and Huainan coalfield, obviously different from those of Qinshui coal basin. Based on the tectono-thermal evolution characters of Huaibei-Huainan coalfields and Qinshui basin, the process of coalbed gas generation can be divided into three stages： （1） Dur- ing Early Mesozoic, both in Huaibei-Huainan and Qinshui, the buried depth of Permian coal seams increased rapidly, which resulted in strong metamorphism and high burial temperature of coal seams. At this stage, the coal rank was mainly fat coal, and locally reached coking coal. These created an environment favoring the generation of thermogenic gas. （2） From Late Ju- rassic to Cretaceous, in the areas of Huaibei-Hualnan, the strata suffered from erosion and the crust became thinning, and the Permian coal-bearing strata were uplifted to surface. At this stage, the thermogenic gas mostly escaped. Conversely, in Qinshui basin, the cover strata of coal seams kept intact during this stage, and the thermogenic gas were mostly preserved. Furthermore, with the interaction of magmatism, the burial temperature of coal seams reached higher peak value, and it was suitable for the secondary generation of thermogenic gas. （3） From Paleogene onward, in area of Huainan-Huaibei, the maturity of coal and burial temperature were propitious to the generation of secondary biogenic gases. However, in Qinshui basin, the maturity of coal went against genesis of second biogenic gas or thermogenic gas. By comparison, Huaibei-Huainan coalfields are dominated by thermogenic gas with a significant biogenic gas and hydrodynamic overprint, whereas Qinshui basin is dominated mainly by thermogenic gas.
文摘This study investigates the paleodepositional conditions of the No.6 Seam of the Madzaringwe Formation in Makhado and Voorburg south area of the Soutpansberg Coalfield(Limpopo Province,South Africa)utilizing organic petrography and inorganic geochemical proxies.The coals are predominantly high-volatile bituminous B-A rank with high ash yields(avg.36.1 wt%),characterized by high-vitrinite(~41.5 vol%),moderate-to-high inertinite(9.8 vol%–33.7 vol%)and low liptinite(~2.3 vol%).The distribution of inertinite varies among different coal horizons(from bottom-lower to middle-upper),suggesting differential oxidation conditions and/or paleofire occurrence.Vitrinite-to-inertinite(V/I)ratio,tissue preservation–gelification index(TPI–GI),and groundwater–vegetation index(GWI–VI)plots,indicate that the peat-forming forest-swamp vegetation accumulated under mesotrophic-to-rheotrophic hydrological conditions.The presence of structured macerals(i.e.,telinite,collotelinite,fusinite,and semifusinite)suggests well-preserved plant tissues,whereas framboidal pyrite and sulphur content(0.24 wt%–2.16 wt%)point to brackish-water influence at the peat stage.The coals contain quartz,kaolinite,siderite,muscovite,dolomite,calcite,and pyrite minerals,most of which were likely sourced from felsic igneous rocks.The Al/(Al+Fe+Mn)and(Fe+Mn)/Ti ratios for the studied samples range between 0.24–0.97 and 0.57–70.10,respectively.The ratios,Al–Fe–Mn plot,and presence of massive botryoidal-type pyrite imply some influence of meteoric waters or fluids from hydrothermal activity post-deposition.Moreover,the chemical index of alteration(CIA:98.25–99.67),chemical index of weathering(CIW:92.04–97.66),and A–CN–K ternary diagram suggest inorganic matter suffered strong chemical weathering,indicating warm paleoclimatic conditions during the coal formation.
基金granted by the National Natural Science Foundation of China(42102297,41972254)Innovative Science and Technology Talents Team Construction Project of Henan Province(CXTD2016053)+2 种基金China Postdoctoral Science Foundation(2021M701098)Special Funds for Higher Education Basic Scientific Research Funds of Henan Province(NSFRF200103NSFRF210304)。
文摘The karst groundwater of Cambrian limestone may become an important water source for industry and agriculture in the Pingdingshan area,and is also a potential threat to mining safety.Therefore,to find out the origin,flow paths,and hydrogeochemical processes of karst groundwater beneath the Pingdingshan coalfield,a total of 16 water samples were collected.Our findings confirmed that the karst groundwater is mainly recharged by precipitation.The precipitation can directly supply the deep aquifer of the karst water system through the southwest limestone outcrops,and this area mostly includes the southern part of mines No.11,No.9,and the hidden outcrops in the southern part of mine No.2.What is more,the areas adjacent to the synclinal axis,including mines No.10,No.12,and No.8,may be the main discharge areas.A mixing model of^(87)Sr/^(86)Sr and Sr showed that in the southwest Pingdingshan coalfield,the proportion of precipitation decreased gradually from the recharge area to the discharge area,ranging from 89.1%to 17.1%.Besides,the northeast Pingdingshan coalfield is another recharge area for the whole karst system,thus,the infiltrating groundwater will indirectly supply the deep aquifer through Quaternary deposition near the mine No.13.Our research results can provide theoretical support for the prevention and control of groundwater disasters and the development and utilization of regional groundwater resources in the coalfield in Northern China.
基金Project(201412016)supported by the Special Fund for Public Projects of National Administration of Surveying,Mapping and Geoinformation of ChinaProject(51174287)supported by the National Natural Science Foundation of China
文摘Numerous coal fires burn underneath the Datong coalfield because of indiscriminate mining.Landsat TM/ETM,unmanned aerial vehicle（UAV）,and infrared thermal imager were employed to monitor underground coal fires in the Majiliang mining area.The thermal field distributions of this area in 2000,2002,2006,2007,and 2009 were obtained using Landsat TM/ETM.The changes in the distribution were then analyzed to approximate the locations of the coal fires.Through UAV imagery employed at a very high resolution（0.2 m）,the texture information,linear features,and brightness of the ground fissures in the coal fire area were determined.All these data were combined to build a knowledge model of determining fissures and were used to support underground coal fire detection.An infrared thermal imager was used to map the thermal field distribution of areas where coal fire is serious.Results were analyzed to identify the hot spot trend and the depth of the burning point.
基金The work presented in this paper is part of a PhD research study in the School of Mining Engineering at the University of the Witwatersrand,Johannesburg,South Africa.
文摘Coal oxidation at low temperatures is the heat source liable for the self-heating and spontaneous combustion of coal. This phenomenon has imposed severe problems in coal related industries. Attempts to understand this phenomenon by previous researchers have provided significant progress. It is wellknown that coal oxidation at low temperatures involves oxygen consumption and formation of gaseous and solid oxidation products. This process is majorly influenced by temperature, oxidation history of coal,coal properties, particle size distribution of the coal, etc. The current understanding of the phenomenon of self-heating and spontaneous combustion of coal is discussed along with the different experimental and numerical models established to predict self-heating characteristics of coal. This paper focuses on the global position of the study carried out by academics, research institutes and industries on spontaneous combustion of coal and coal mine fires. Within this framework, the generally used spontaneous combustion techniques to predict the spontaneous combustion liability of coal were evaluated. These techniques are well-known in their usage, but no specific method has become a standard to predict the spontaneous combustion liability. Further study is still needed to indicate a number of impending issues and to obtain a more complete understanding on the phenomenon.
文摘This study presents a review of the various methods to predict the spontaneous combustion liability of coal and coal-shale. The relative propensity of coal to undergo self-heating can be established by different methods. These methods are well established in their usage, but the fact that no particular test method has become a standard to predict the spontaneous combustion liability indicates that doubt still exists as to the validity of all of them. The underlying principle of all the tests is that the more readily the coal undergoes exothermic oxidation, the more liable it is to self-heat. Comprehensive studies that centres on the international position on research being conducted by academics, different research institutes and industries on spontaneous combustion of coal and coal mine fires were evaluated. Relationships between the geochemical analysis (proximate and ultimate analysis, forms of sulphur, petrographic properties, X-ray diffraction and X-ray fluorescence) and spontaneous combustion testing methods (numerical and experimental approaches) used to predict the spontaneous combustion liability of coal were reviewed. The combination of these tests provides a better understanding of the mechanism that controls the spontaneous combustion phenomena. However, irrespective of the extensive studies that have been conducted over time, spontaneous combustion is still a major problem in the coal value chain.
基金financially supported by the National Science Fundamental of China Projects(Nos.41072115 and 51174262)the project of the Science Foundation of Hebei(No.D2011402034)
文摘Total 138 coal samples and 14 parting samples were taken from the No. 6 Seam of the Jungar Coalfield, Inner Mongolia. These samples were analysed by optical microscopy, sequential chemical extraction procedure （SCEP）, inductively coupled plasma mass spectrometry （ICP-MS）, X-ray powder diffraction （XRD）, and scanning electron microscope in conjunction with an energy-dispersive X-ray spectrometer （SEM-EDX） analysis. The results indicate that the Li contents have reached the industrial grade of the coal associated Li deposit, and the total Li reserves have reached 2406600 tons, that is, 5157000 tons Li2O in the No. 6 seam in the Jungar Coalfield. The sequential chemical extraction procedure results suggest that the Li concentration is mainly related to inorganic matter. The minerals in the coals consist of kaolinite, boehmite, chlorite-group mineral, quartz, calcite, pyrite, siderite and amorphous clay material. Some Li could be absorbed by clay minerals in the Li-bearing coal seam. The chlorite phase？could be？most likely the host for a part of Li. The Yinshan Oldland should be the most possible source of Li of the coal.
文摘This paper discussed the petrographic characteristics of No.6 coal from the Xiaoyugou mine,Jungar Coalfield,Ordos Basin,China.10 samples(7 coal,1 parting mudstone and 2 floor mudstone)were analysed by microscopical and geochemical methods.Four maceral compositions and several associated elements parameters were selected as indicators and corresponding diagrams were drawn to explicate the sedimentary environment.The results indicate that the maceral is dominated by vitrinite and minerals are mainly kaolinite in the No.6 coal.The sedimentary facies vary from barrier island system to tidal-flat which is a deposition process of water body shallowing and the coal-forming plants are herbs and woody plants formed in swamps.
文摘Based on the systematic analysis of the coal gangue in Weibei Coalfield, such as petrologic characteristics, chemical composition, nutrient elements, deleterious elements, and the transformation, and compared with the soil element content background values of Loess Plateau and national harmful materials controlling standards, we conclude that the coal gangue in the Weibei Coalfield has huge potential to be used as clay fertilizer.
基金National Natural Science Foundation Project (Grant No. 41662010)Xinjiang Uygur Autonomous Region University Scientific Research Program For Young Teachers Research And Cultivation Fund Project (Grant No. XJEDU20I6S038).
文摘Santanghu Coalfield is the largest integrated coalfield exploration area in China. The major coal seams developing in Xishanyao Formation (Middle Jurassic) are the high-quality steam coals characterized by large thickness, favorable horizontal continuity and high coal quality. In this paper, twenty-two samples were collected from the three typical boreholes in Hanshuiquan disirict, representing the 11 coal seam sequences (7#,8#,9#,13#, 14#,15#,17#,18#,19#,20#,22#), respectively. The petrographic characteristics of the coal-bearing sequence in Xishanyao Formation were firstly summarized systematicly, and then the coal-forming swamp characteristics and succession mechanism of the coal seam in Xishanyao Formation were defined by analyzing the samples. The maceral composition, structure, geochemical and geophysical characteristics of coal are in eluded in original genetic criteria of coal-forming swamp an alysis. And the composition of coal petrography, maceral and microlithotype are the most frequently used parameters. Coal is composed of microscopic constituents and inorganic substances. The Xishanyao Formation maceral mainly consists of vitrinite (65.74%-97.01 %), inert i nite (1.93%-34%), and the exinite shows the mode of regular change. The coal-forming swamp in Xishanyao Formation possesses the characteristics of mainly marsh, wet forest swamp facies, and shallow water covered forest swamp facies, and a few of coal seams distribute in the deep water covered forest swamp facies. In addition, the sporopollens in Xishanyao Formation are mainly Pinaceae evergreen broad leaf and needle-leaved plants. Osmundaceae, Cyatheaceae and Lygodiaceae, indicating that the warm and humid tropic-subtropical climate conductive to the persistent growth of coal-forming plants in the Middle Jurassic. The coal-forming swamp shows the characteristics of vertically upward fluctuation through the periodic transition. It indicates a shallow-deep-shallow change process of the water covered depth in the swamp. This is the prin ci pal factor for the formation of the high-quality and continuous coal seam in Hanshuiquan district, Santanghu Coalfield.
基金supported by the China geological survey project"Qaidam Basin Oil and Gas Resources Evaluation"(Nr:([2013]4-(3),001-008)National Natural Science Foundation of China(No.41330317)
文摘Total of 23 bench samples were taken from the No. 7 Coal of Iqe Coalfield, Qinghai Province, China, following Chinese Standard Method GB/T 482-2008 （2008）. These samples were analyzed by powder X-ray diffraction （XRD）, inductively coupled plasma mass spectrometry （ICP- MS） and X-ray fluorescence （XRF）. The results indicate that the No. 7 Coal belongs to a low rank （Ro.ran =0.659%） and high-ash coal （40.54%）. Compared to common Chinese and world low-rank coals, the lqe coal contains anomalous concentrations of rare metal elements, rare-scattered （dispersed） elements and rare earth elements. The highest contents of Rb, Cs, Ga and REY reach to 180, 26, 37, and 397 ppm, respectively. Their average contents of these elements are 10.9, 15, 4.8 and 3.5 times higher than those of world coals, respectively. Minerals in the coal include kaolinite, quartz, muscovite, siderite, and traces of rutile, and brookite. Kaolinite could be main host minerals of Rb, Cs, Ga and REY. The anomalous rare element Rb and Cs accumulation in the Iqe coal is related to both organic and inorganic matter. The REY concentrations may be related to circulation of thermal solutions, contained or sorbed by clayey particles, and organic matter as well.
基金funded by Coaltech and is part of a PhD research/Postdoctoral study in the School of Mining Engineering at the University of the Witwatersrand
文摘Coal and coal-shale undergo low-temperature oxidation when exposed to air,potentially leading to spontaneous combustion.Coal-shale found in association with coal seams vary considerably in their intrinsic properties and spontaneous combustion liability index.Fourteen coal-shale samples collected from four different coal mines in Witbank Coalfield,South Africa,were experimentally investigated.The influence of coal-shale intrinsic properties and spontaneous combustion liability indices(determined by the WitsEhac Index and the Wits-CT Index)were established.The liability indices indicate relationships with the intrinsic factors and thus,identifying the major intrinsic factors affecting liability toward spontaneous combustion in these coal-shale samples.The XRF analysis indicated that the coal-shale samples are rich in Si O2,Al2O3 and Fe2O3,while the XRD showed that same coal-shale samples are generally dominated with kaolinite and quartz.The coal-shale occurred in association with medium Rank C bituminous coal and contained varying proportion of macerals.The Wits-Ehac Index was unable to reliably determine liability indices of some coal-shale samples,and hence the Wits-CT Index was developed.The results obtained from the characterisation tests may be used as a tool to predict the spontaneous combustion liability in carbonaceous material and may serve as a reference when comparing coal-shale from different coal mines.
基金Under the auspices of International Program for Cooperation in Science and Technology (No. 2007DFA20640)National High Technology Research and Development Program of China (No. 2009AA12Z146, 2009AA12Z124)National Natural Science Foundation of China (No. 40701172)
文摘Coal fire burning around the world is an environmental catastrophe characterized by the emission of noxious gases, particulate matter, and condensation by-products. In this study, coal fire temperature is retrieved based on Landsat 5 TM images and Generalized Single-Channel Algorithm (GSCA), in Wuda coalfield, Inner Mongolia, China. Then coal fire zones are extracted by Jenks′ natural breaks and threshold methods based on temperature images. Changes of coal fire zones are analyzed from 1989 to 2008. The results are summarized as follows: 1) The coal fire temperature retrieval method based on Landsat 5 TM and the GSCA model is effective and feasible, because the temperature error is relatively small (from –2.9℃ to +2.6℃) between the measured temperature and the retrieved temperature. 2) The accuracy is relatively high to extract coal fire zones through the Jenks′ natural breaks and threshold methods, because 83.56% of surveyed area is located in the coal fire zones extracted in 2005. 3) The coal fire area increased 9.81 × 10 5 m 2 from 1989 to 2005, and the annual growth is about 6.1 × 10 4 m 2 , with an annual increasing rate of 2.48%. The area of coal fire decreased by 8.1 × 10 5 m 2 from 2005 to 2008.
基金supported by a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Fundamental Research Funds for the Central Universities 2014QNA88the National Natural Science Foundation(No.41674133)
文摘Water flooding disasters are one of the five natural coal-mining disasters that threaten the lives of coal miners. The main causes of this flooding are water-conducting fractured zones within coal seams. However, when resistivity methods are used to detect water-conducting fractured zones in coal seams, incorrect conclusions can be drawn because of electrical anisotropy within the water-conducting fractured zones. We present, in this paper, a new geo-electrical model based on the geology of water-conducting fractured zones in coal seams. Factors that influence electrical anisotropy were analyzed, including formation water resistivity, porosity, fracture density, and fracture surface roughness, pressure, and dip angle. Numerical simulation was used to evaluate the proposed electrical method. The results demonstrate a closed relationship between the shape of apparent resistivity and the strike and dip of a fracture. Hence, the findings of this paper provide a practical resistivity method for coal-mining production.
基金Projects Y2007F46 supported by the Natural Science Foundation of Shandong Province20070424005 by the Doctor Disciplines Special Scientific Researc Foundation of the Ministry of Education+1 种基金108158 by the Key Project of the Ministry of Education of China50539080 by the National Natural Scienc Foundation of China
文摘The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone aquifers.Our study describes the mechanism of mine water inrushes through a fault in the mine floor using principles of strata mechanics and the path of water inrush from an aquifer to the working face.A criterion to judge whether a ground water inrush will occur through a fault or not is also described, together with a case history of water inflow in the Feicheng coalfield, China.
文摘Heavy mining of Jurassic and Carboniferous horizontal coal seams in the Datong coalfield has seriously affected the local geological environment, which is mainly manifested by such geohazards as soil avalanches, landslides, mudflows, surface subsidence, surface cracks, surface solid waste accumulation and surface deformation. More seriously, coal mining causes groundwater to leak. Overpumping of groundwater has resulted in substantial land subsidence of the urban area in Datong City. Based on the previous geo-environmental investigation in the work area, the authors used radar remote sensing techniques such as InSAR （synthetic aperture radar interferometry） and D-InSAR （differential synthetic aperture radar interferometry）, supplemented by the optical remote sensing method, for geo-environmental investigation to ascertain the geo-environmental background of the Datong Jurassic and Carboniferous-Permian coalfield and evaluate the effects of the geohazards, thus providing a basis for the geo-environmental protection, geohazard control and prevention, land improvement and optimization of the human environment. In this study 8 cog-nominal ERS-1/2 SAR data frames during 1992 to 2003 were used, but the following processing was made： （1） the multitemporal SAR magnitude images were used to interpret the geological structure, vegetation, microgeomorphology and drainage system; （2） the multi-temporal InSAR coherent images were used to make a classification of surface features and evaluate the coherence change due to coal mining; and （3） the multi-temporal cog-nominal SAR images were used to complete D-InSAR processing to remove the information of differential deformation areas （sites）. In the end, a ten-year time series of differential interferograms were obtained using the multi-temporal cog-nominal SAR images. In the tests, 84 deformed areas （sites） were obtained, belonging to those in 1993-1996, 1996-1997, 1997-1998, 1998-2001, 1998-2002 and 2001-2003 respectively. Of the 84 areas, 44 are mining subsidence ones, 23 urban subsidence ones and 17 landslide subsidence ones. They cover a total area of 1824.4 km^2, equivalent to the area of the whole Datong coalfield. Then an accurate evaluation was made on the geo-environment of the Datong coalfield. The tests show that InSAR is now the only feasible technical means for making one all-weather, real-time measurement of a coal mining land subsidence area covering up to 10,000 km^2 to subcentimeter resolution. This study is a successful application of InSAR in the investigation and evaluation of land subsidence, especially in coal mining areas.
