Coal pore parameters are closely related to macrolithotypes and coal structures,having a large influence over the gas potential and productivity of coalbed methane(CBM).The Middle Jurassic Xishanyao Formation,located ...Coal pore parameters are closely related to macrolithotypes and coal structures,having a large influence over the gas potential and productivity of coalbed methane(CBM).The Middle Jurassic Xishanyao Formation,located in the southern Junggar Basin of northwestern China,has geological conditions with rich CBM resources.The 46 Xishanyao coal samples gathered from the drilling cores and coal mines cover 4 types of macrolithotypes(bright coal 1,semi-bright coal 2,semi-dull coal 3,and dull coal 4)and 2 types of coal structures(primary coal I and cataclastic coal II).Based on a range of pore testing experiments and analytical methods,the dual effects of different macrolithotypes and coal structures on pore structures were intensely studied.The results showed that the specific surface area(SSA)and total pore volume(TPV)of coal samples increased gradually from bright to dull coals.For the same macrolithotypes,the SSA and TPV of the primary coals were lower than those of the cataclastic coals.Generally,the pore structures of bright and semi-bright coals are simpler when compared to semi-dull and dull coals with the same coal structure,whereas cataclastic coals have more complicated pore structure systems than primary coals with the same macrolithotypes.The bright and semi-bright coals have higher vitrinite contents and more endogenous fractures,whereas well-developed structural fractures were identified in cataclastic coals.Therefore,bright and semi-bright coals have better pore connectivity than semi-dull and dull coals with the same coal structure,the pore connectivity of cataclastic coals being slightly better than that of primary coals under the same macrolithotypes.In terms of the CBM adsorption conditions,the eight type samples formed a descending order:Ⅱ-4>I-4>Ⅱ-3>Ⅰ-3>Ⅱ-2>Ⅰ-2>Ⅱ-1>Ⅰ-1,while they ranked as follows when consideration was given to the CBM seepage capacities:II-2>Ⅱ-1>Ⅰ-2>Ⅰ-1>Ⅰ-3>Ⅰ-4>Ⅱ-3>Ⅱ-4.As a result,it could be determined that the bright and semi-bright coals had stronger adsorption capacities,whereas the cataclastic coals had better pore connectivity and seepage capacities.Pore structure characteristics should be analysed under the dual control of different macrolithotypes and coal structures,so that they can provide greater value for guiding CBM exploration and exploitation,as along for preventing underground gas accidents.展开更多
Gas injection-enhanced underground coal combustion for heat extraction represents a disruptive chemical fluidized extraction method of coal resources.Coal seam combustion dynamics provide crucial underpinnings for eng...Gas injection-enhanced underground coal combustion for heat extraction represents a disruptive chemical fluidized extraction method of coal resources.Coal seam combustion dynamics provide crucial underpinnings for engineering realization.This study establishes an experimental system for monitoring temperature field evolution during gas-assisted combustion in cylindrical coal cores,investigating the influence of moisture content(0%,16%,24%)on gas-assisted combustion kinetics.Results showed moisture content significantly influences combustion:higher levels(16%-24%)delay high-temperature expansion(0-1 h)due to evaporation energy absorption,but subsequently enhance efficiency through pore formation and oxygen diffusion,achieving 1120-1230°C peaks.Dry coal exhibits rapid initial combustion(peak temperature of 1130°C within 1 h)but weaker sustained reactions.The temperature field evolves from localized hotspots to an elliptical high-temperature zone,with axial expansion rates surpassing radial rates,driven by thermal buoyancy and convective heat transfer.Moisture’s dual role is revealed:initially as a thermodynamic inhibitor and later as a promoter by increasing pore diameter and oxygen diffusion coefficients.An optimal moisture content of 16%balances initial heat loss with enhanced reactivity,offering practical insights for optimizing gas injection and thermal recovery in underground coal combustion.展开更多
This research presents the results of a comprehensive study of mineralogical and geochemical features of REE distribution in coals of Central Kazakhstan deposits—Karaganda coal basin and Shubarkol deposit,which have ...This research presents the results of a comprehensive study of mineralogical and geochemical features of REE distribution in coals of Central Kazakhstan deposits—Karaganda coal basin and Shubarkol deposit,which have large hard coal reserves and are industrially important for the coal industry of Kazakhstan;the research is based on 205 samples of clayey interlayers and coal seams.It shows basic patterns of distribution and features of concentration for impurity elements,gives an estimate of the impurity elements concentration,including REE,defines conditions and factors of their accumulation,and studies features of their forms in coal and coal-bearing rocks,which allows estimating the mechanisms of their migration and conditions of accumulation.According to the results of geochemical indicators,the article establishes the factors of REE dislocation,reveals the composition of margin rocks that have influenced REE concentration in coal seams,and the presented latest data on mineralogy allowed to establish the ways of their transportation to the paleobasin during the synand epigenetic periods of formation of the coal deposits of Central Kazakhstan being researched.It was found that the coals are insignificantly enriched with heavy lanthanides from Ho to Lu.The distribution curves of UCC normalized REE values in the coals are similar and coincide,but they are less than the average value for world coal,and amount to only one-third of the UCC.It was found that the highest concentrations of all REE are characteristic of clayey interlayers and oxidized coals.The La/Yb ratio in this case increases upwards along the section,indicating mainly clastogenic mechanism of REE delivery to the coals.In coal and clay samples,the predominant mineral form of REE is light lanthanide phosphates.Identified particles of REE from minerals and their composition peculiarities suppose autigene nature of their formation.The formation of the bulk of autigene minerals occurred during the maturation of brown coals and their transformation into hard ones.展开更多
In order to comprehend the applicability of microwave irradiation for recovering coalbed methane,it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism.I...In order to comprehend the applicability of microwave irradiation for recovering coalbed methane,it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism.In this work,the carbon molecular sieve combined with KMnO_(4)oxidation was selected to fabricate carbon molecular sieve with diverse oxidation degrees,which can serve as model substances toward coals.Afterwards,the microwave irradiation dependences of pores,functional groups,and highpressure methane adsorption characteristics of model substances were studied.The results indicated that microwave irradiation causes rearrangement of oxygen-containing functional groups,which could block the micropores with a size of 0.40-0.60 nm in carbon molecular sieve;meanwhile,naphthalene and phenanthrene generated by macro-molecular structure pyrolysis due to microwave irradiation could block the micropores with a size of 0.70-0.90 nm.These alterations in micropore structure weaken the saturated methane adsorption capacity of oxidized carbon molecular sieve by 2.91%-23.28%,suggesting that microwave irradiation could promote methane desorption.Moreover,the increased mesopores found for oxidized carbon molecular sieve after microwave irradiation could benefit CH4 diffusion.In summary,the oxidized carbon molecular sieve can act as model substances toward coals with different ranks.Additionally,microwave irradiation is a promising technology to enhance coalbed methane recovery.展开更多
Methane(CH_(4))and carbon dioxide(CO_(2))are primary components of coal seam gas(CSG).Understanding their adsorption-desorption hysteresis characteristics,along with the fundamental mechanism,is crucial for CSG exploi...Methane(CH_(4))and carbon dioxide(CO_(2))are primary components of coal seam gas(CSG).Understanding their adsorption-desorption hysteresis characteristics,along with the fundamental mechanism,is crucial for CSG exploitation and related hazards mitigation.This research focused on the representative Bulli coal seam in the Sydney Basin,Australia.Through the purpose-built indirect gravimetric high-pressure isothermal adsorption-desorption hysteresis experiment,a novel Langmuir-based desorption model,incorporating hysteresis effect and residual gas,was proposed.Quantitative characterization of the adsorption-desorption hysteresis degrees of CO_(2)and CH_(4)i n coal particles of various sizes and inΦ50mm 100 mm intact coal samples were achieved using the improved hysteresis index(IHI).The experimental findings validated that the proposed desorption model accurately describes the desorption behavior of CO_(2)and CH_(4)in coal(R^(2)>0.99).Based on the adsorption-desorption properties of inkbottle-shaped micropores and pore deformation caused by gas adsorption-induced coal expansion,the occurrence mechanism of adsorption–desorption hysteresis and the fundamental reasons for the presence of residual gas were elucidated.Furthermore,the study explored the impact of CO_(2)and CH_(4)adsorption-desorption hysteresis effects on coal and gas outbursts,suggesting that coal seams rich in CO_(2)do not have a higher propensity for outbursts than those rich in CH_(4).展开更多
Forty Tertiary coals from Mukah-Balingian and Merit-Pila coalfields of the Sarawak Basin,Malaysia were investigated using bulk and molecular geochemical techniques such as proximate analysis,gas chromatography-mass sp...Forty Tertiary coals from Mukah-Balingian and Merit-Pila coalfields of the Sarawak Basin,Malaysia were investigated using bulk and molecular geochemical techniques such as proximate analysis,gas chromatography-mass spectrometry,elemental analyser,isotope ratio mass spectrometry,and inductively coupled plasma mass spectrometry to reconstruct their paleovegetation,paleoclimate,and environments of deposition.In addition,principal component analysis(PCA)of selected geochemical parameters was carried out to determine the controlling influences on the petroleum potential of the humic coals.s13C values and the abundance of terpenoids imply the predominant contribution of angiosperms to the paleoflora.Bimetal proxies(Sr/Ba,Sr/Cu,and C-value),andδD values are generally suggestive of a warm and humid climate during the accumulation of the paleopeats.However,n-alkane proxies(P_(wax),P_(aq),n-C_(23)/n-C_(29),etc.)and polycyclic aromatic hydrocarbons(PAHs)distribution suggest that Balingian coals accumulated under relatively drier and strongly seasonal palcoclimate in the Late Pliocene.When compared with published global average abundances,the investigated coals are mostly depleted in major oxides and trace elements,suggesting peat accumulation in freshwater-influenced environments.Nonetheless,higher(>0.5 wt%)total sulfur content in some Mukah-Balingian coals suggests some degree of epigenetic marine influence.Fur-thermore,the low to moderately-high ash contents of the Sarawak Basin coals indicate the presence of ombrotrophic and rheotrophic peat deposits.PCA result of selected geochemical proxies suggests that source input,paleoflora,and marine incursions are not major controlling influences on the petroleum potential.However,climatic,and depositional conditions appear to slightly influence the petroleum potential of the studied humic coals.展开更多
Special attention was drawn to the heavy metals contained in coal,due to it will cause harm to the environment during coal processing and utilization.The sequential chemical extraction of Shanxi coal(SX coal)and Wulan...Special attention was drawn to the heavy metals contained in coal,due to it will cause harm to the environment during coal processing and utilization.The sequential chemical extraction of Shanxi coal(SX coal)and Wulanchabu coal(WLCB coal)was carried out to investigate the distribution of arsenic(As)in coals.Two raw coals were pyrolyzed at 300-900℃ in horizontal tubular furnace to investigate release behavior of As during pyrolysis process.The results showed that As in SX coal mainly existed in aluminosilicate-bound state(40.25%)and disulfide-bound state(32.51%),followed by carbonate-bound state and organic-bound state.The As in WLCB coal mainly existed in aluminosilicate-bound state(62.50%),followed by disulfide-bound state(19.10%).The As contents of water-soluble,ion-exchange and residue states in the two coals were less than others.The modes of occurrence of As had great infuence on its volatilization behavior.As in organic part was easy to volatilize at low temperature.Sulfide-bound state would escape with the decomposition of pyrite.Because SX coal contained higher organic state and sulfide-bound state,the volatilization rate of As was higher than WLCB coal at any temperature,and the difference was more obvious at low temperature.In addition,FactSage simulation value was basically consistent with the experimental value.展开更多
Solvent-extracted fractions of six Indian coal samples of different ranks were investigated using multiple geochemical,petrological and spectroscopic proxies and an attempt was made to indicate possible fingerprint re...Solvent-extracted fractions of six Indian coal samples of different ranks were investigated using multiple geochemical,petrological and spectroscopic proxies and an attempt was made to indicate possible fingerprint regions for different polycyclic aromatic hydrocarbons(PAH)with the help of excitation-emission matrix(EEM).In this study,for the very first time,the influence of rank and maturation of organic matter in the characterisation of coal solvent-extracts from Indian coals were perceived from the viewpoint of fluorescence EEM.Vitrinite reflectance(VR_(0))values were used to determine the general ranks of the original coal samples viz.lignite,subbituminous,bituminous and anthracite.Different fluorescence peak regions corresponding to different fused aromatic ring(FAR)systems were delineated using the EEM and their indicative depositional environments could be inferred.Our observations indicate that solvent-extracted fractions of low rank coals comprise of a larger number of shorter carbon chains compared to the other samples.For the low rank coal samples,the solvent-extracts show a strong humic influence and the presence of smaller PAH rings while for the medium rank coals,the extracted fractions tend to show a more bimodal distribution of PAHs,possibly comprising of different sized PAHs.Higher fluorescence sensitivity and quick response of smaller PAHs impart a singular centralised region in the EEM for the low rank coal samples while interference in the fluorescence of differently sized PAHs indicate a multimodal distribution of the fluorophores in the medium rank coals.The high rank coal used in this study shows a bimodal distribution with very low intensity of the peaks,indicating the low abundance of extractable macromolecules,possibly as a result of deformation.展开更多
The enhanced coalbed methane recovery using CO_(2) injection(CO_(2)-ECBM)is widely proposed as a way of achieving the energy transition and reducing atmospheric CO_(2),in areas such as the Lorrain basin in France,wher...The enhanced coalbed methane recovery using CO_(2) injection(CO_(2)-ECBM)is widely proposed as a way of achieving the energy transition and reducing atmospheric CO_(2),in areas such as the Lorrain basin in France,where heavy industry is responsible for huge CO_(2) emissions and coal mines have been closed for more than a decade.This paper deals with the feasibility of extracting methane from the Lorraine basin using CO_(2)-ECBM by comparing data from sorption isotherms,thermogravimetric analyses and breakthrough curves for two coal samples.One is bituminous(Box 18),from Folschviller(France)and is compared with another sub-bituminous(THO1)from La Houve(France),which is used as a reference because it was identified as a good candidate for CO_(2)-ECBM in a previous research program.The quantities of adsorbed gases(CO_(2)/CH_(4))obtained by sorption isotherms,thermogravimetry and CO,breakthrough curves showed that Box 18 adsorbs more CO_(2) and CH_(4) than THO1 due to its higher porosity and good affinity for gases(CO_(2)/CH_(4)).Toth model fits the experimental CH_(4) and CO_(2) adsorption isotherms better,reflecting the fact that the adsorption surface of the coals studied is heterogeneous.Adsorption enthalpies obtained by calorimetry indicated physisorption for gas-coal interactions,with higher values for CO_(2) than for CH_(4).Thermogravimetric analyses and breakthrough curves carried out at up to 50%relative humidity showed that the adsorption capacity of CO_(2) decreases with increasing temperature and the presence of water,respectively.The compilation of these experimental data explained the adsorption process of the studied coals and revealed their advantages for CO_(2)-ECBM.展开更多
Coal has been used as an energy resource around the world, primarily for the generation of electricity. The cleaning of coal by removing its unwanted sulfur and mineral matter components is utmost essential before the...Coal has been used as an energy resource around the world, primarily for the generation of electricity. The cleaning of coal by removing its unwanted sulfur and mineral matter components is utmost essential before their gainful utilizations. The ionic liquids （ILs） are considered as non-toxic solvents for using in different industrial processes. The effect of two ILs namely, 1-n-butyl, 3-methylimidazolium tetrafluoro borate （ILl） and 1-n-butyl, 3-methylimidazolium chloride （IL2） in oxidative de-sulfurization and de-ashing of two industrially important high sulfur coal samples from Meghalaya （India） is discussed in this paper. The maximum removal of total sulfur, pyritic sulfur, sulfate sulfur and organic sulfur are observed to be 37.36 %, 62.50 %, 83.33 % and 31.63 % respectively during this oxidative process. The quantitative diffuse reflectance Fourier transform-infrared spectroscopy analysis supports the formation of sulfoxides （S--O） and sulfones （-SO2） and their subsequent removal during the oxidation of the coals in presence of ILs. The X-ray fluorescence combined with near edge X-ray absorption fine structure and scanning electron microscopic studies reveal the removal of mineral matters （ash yields） from the coal samples. The thermogravimetric analysis of the raw and clean coals indicates their high combustion efficiencies and suitability for using in thermal plants. The method is partially green and the ILs could be recovered and reused in the process.展开更多
The macromolecular structure of tectonically deformed coals(TDC)may be determined by the deformation mechanisms of coal.Alterations of the macromolecular structure change the pore structure of TDC and thereby impact p...The macromolecular structure of tectonically deformed coals(TDC)may be determined by the deformation mechanisms of coal.Alterations of the macromolecular structure change the pore structure of TDC and thereby impact physical properties such as porosity and permeability.This study focuses on structure and properties of TDC from the Huaibei and Huainan coal mining areas of southern North China.Relationships between the macromolecular structure and the pore structure of TDC were analyzed using techniques such as X-ray diffraction,high-resolution transmission electron microcopy,and the low-temperature nitrogen adsorption.The results indicated that the directional stress condition can cause the arrangement of basic structural units(BSU)more serious and closer.And,the orientation is stronger in ductile deformed coal than in brittle deformed coal.Tectonic deformation directly influences the macromolecular structure of coal and consequently results in dynamic metamorphism.Because the size of BSU in brittle deformed coal increases more slowly than in ductile deformed coal,frictional heating and stress-chemistry of shearing areas might play a more important role,locally altering coal structure under stress,in brittle deformed coal.Strain energy is more significant in increasing the ductile deformation of coal.Furthermore,mesopores account for larger percentage of the nano-scale pore volume in brittle deformed coals,while mesopores volume in ductile deformed coal diminishes rapidly along with an increase in the proportion of micropores and sub-micropores.This research also approved that the deformations of macromolecular structures change nano-scale pore structures,which are very important for gas adsorption and pervasion space for gas.Therefore,the exploration and development potential of coal bed methane is promising for reservoirs that are subjected to a certain degree of brittle deformation(such as schistose structure coal,mortar structure coal and cataclastic structure coal).It also holds promise for TDC resulting from wrinkle structure coal of low ductile deformation and later superimposed by brittle deformation.Other kinds of TDC suffering from strong brittle-ductile and ductile deformation,such as scale structure coal and mylonitic structure coal,are difficult problems to resolve.展开更多
The use of high As-bearing coals has caused more than 3,000 cases of arsenosis patients in southwest Guizhou Province, China. The mode of occurrence of arsenic in coal is an important key role in understanding its beh...The use of high As-bearing coals has caused more than 3,000 cases of arsenosis patients in southwest Guizhou Province, China. The mode of occurrence of arsenic in coal is an important key role in understanding its behavior during usage and damage pathway to human health. Coal samples from endemic arsenosis areas were analyzed with INAA, EMPA, SEM-EDX, LTA, XRD, XAFS, and sequential leaching experiment. Arsenic in pyrite is from under the limit of EMPA to 1.75%, and in most cases, the content of arsenic is lower than 0.5%. Besides pyrite and arsenopyrite, SEM-EDX combined with LTA and XRD find that sulfates, clay and phosphates also contain arsenic. XAFS shows that arsenic mainly exists in the form of As^5＋. More than 50% of arsenic stayes in residual solid and combined with organic matrix in two samples, but most arsenic is leached out in other samples. The occurrence of such exceptionally high As contents in coal and the fact that the arsenic is dominantly organically associated are unique observations.展开更多
Minerals in the Late Permian coals from the Niuchang-Yigu mining area,Zhenxiong County,northeastern Yunnan,China,were investigated using optical microscopy and low temperature ashing plus X-ray diffraction(LTA?XRD).Th...Minerals in the Late Permian coals from the Niuchang-Yigu mining area,Zhenxiong County,northeastern Yunnan,China,were investigated using optical microscopy and low temperature ashing plus X-ray diffraction(LTA?XRD).The results showed that minerals in the coal LTAs are mainly quartz,kaolinite,chamosite,mixed-layer illite/smectite(I/S),pyrite,and calcite,with trace amounts of marcasite,dolomite,and bassanite.The authigenic quartz generally occurs in collodetrinite or as a filling in cleats or cell cavities.This silica was mainly derived from aqueous solutions produced by the weathering of basaltic rocks in the Kangdian Upland and from hydrothermal fluids.The presence of b-quartz paramorph grains in collodetrinite probably indicates that these grains were detrital and came from a volcanic ash.Clay minerals are generally embedded in collodetrinite and occur as cell-fillings.Pyrite occurs as framboidal,anhedral,and euhedral grains and a cell-filling.The coals are high in pyrite and the high pyrite content probably results from seawater invading during the stage of peat accumulation.Calcite generally occurs as vein-fillings,indicating an epigenetic origin.展开更多
In this study,the physicochemical,microstructural,mineralogical,thermal,and kinetic properties of three newly discovered coals from Akunza(AKZ),Ome(OME),and Shiga(SHG)in Nigeria were examined for potential energy reco...In this study,the physicochemical,microstructural,mineralogical,thermal,and kinetic properties of three newly discovered coals from Akunza(AKZ),Ome(OME),and Shiga(SHG)in Nigeria were examined for potential energy recovery.Physicochemical analysis revealed high combustible but low levels of polluting elements.The higher heating values ranged from 18.65 MJ/kg(AKZ)to 26.59 MJ/kg(SHG).Microstructure and mineralogical analyses revealed particles with a rough texture,surface,and glassy lustre,which could be ascribed to metals,quartz,and kaolinite minerals.The major elements(C,O,Si,and Al),along with minor elements(Ca,Cu,Fe,K,Mg,S,and Ti)detected are associated with clays,salts,or the porphyrin constituents of coal.Thermal analysis showed mass loss(ML)ranges from 30.51%to 87.57%and residual mass(RM)from 12.44%to 69.49%under combustion(oxidative)and pyrolysis(non-oxidative)TGA conditions due to thermal degradation of organic matter and macerals(vitrinite,inertinite and liptinite).Kinetic analysis revealed the coals are highly reactive under the oxidative and non-oxidative conditions based on the Coats-Redfem Model.The activation energy(Ea)ranged from 23.81 to 89.56 kJ/mol,whereas the pre-exponential factor(kQ)was from 6.77×10^(-4)/min to 1.72×10^(3)/min under pyrolysis and combustion conditions.In conclusion,the coals are practical feedstocks for either energy recovery or industrial applications.展开更多
The present work aims at studying five Indian coals and their solvent extracted clean coal products using Py-GCMS analysis and correlating the characterization data using theoretical principal component analysis.The p...The present work aims at studying five Indian coals and their solvent extracted clean coal products using Py-GCMS analysis and correlating the characterization data using theoretical principal component analysis.The pyrolysis products of the original coals and the super clean coals were classified as mono-,di-and tri-aromatics,while other prominent products that were obtained included cycloalkanes,n-alkanes,and alkenes ranging from C_(10)-C_(29).The principal component analysis is a dimensionality reduction technique that reduced the number of input variables in the characterization dataset and gave inferences on the relative composition of constituent compounds and functional groups and structural insights based on scores and loading plots which were consistent with the experimental observations.ATR-FTIR studies confirmed the reduced concentration of ash in the super clean coals and the presence of aromatics.The Py-GCMS data and the ATR-FTIR spectra led to the conclusion that the super clean coals behaved similarly for both coking and noncoking coals with high aromatic concentrations as compared to the raw coal.Neyveli lignite super clean coal was found to show some structural similarity with the original coals,whereas the other super clean coals showed structural similarity within themselves but not with their original coal samples confirming the selective action of the e,N solvent in solubilizing the polycondensed aromatic structures in the coal samples.展开更多
Igneous intrusion into coal-bearing strata can cause an abrupt increase of temperature-pressure and trigger hydrothermal circulation at the igneous rock-coal contact zone. The conductive heat of intruded lnagma and co...Igneous intrusion into coal-bearing strata can cause an abrupt increase of temperature-pressure and trigger hydrothermal circulation at the igneous rock-coal contact zone. The conductive heat of intruded lnagma and convective migration of secondary hydrothermal fluids have been observed to significantly alter the concentrations and modes of occurrence of mercury （Hg） in thermally-intruded coals.展开更多
The analyses of different sulfur forms, the trace elements in pyrites using electron microprobe and the trace elements in coal using INAA (instrumental neutron activation analysis) of the Late Paleozoic coals from the...The analyses of different sulfur forms, the trace elements in pyrites using electron microprobe and the trace elements in coal using INAA (instrumental neutron activation analysis) of the Late Paleozoic coals from the Taozao coalfield in Shandong Province, China, conclude that most sulfur (>75 %) in high-sulfur coal of Taiyuan Formation occurred as pyrite, in which many hazardous elements co-existed and their concentrations varied with their geological origin. The concentrations of hazardous elements in high-sulfur coals from Taiyuan Formation, composing mainly of Cu, As, U, Pb, Mo and Co, are much higher than those in the low-sulfur coals from Shanxi Formation and Shihezi Formation, because the influence of seawater during and after coal accumulation in Taiyuan Formation is stronger than those in Shanxi and Shihezi formations. Moreover, the element As is related to Fe, and both elements exist mainly in the form of pyrite. The element U is richer in the coal influenced by seawater. In addition, the coal affected by the magmatism contains more U, too. When high-sulfur coals are processed with heavy media washing to remove sulfur and minerals, the majority of hazardous elements will also be removed from the coals.展开更多
Two Nigerian coals, Lafia-Obi and Chikila were blended in the mass ratio of 70:30 with imported American and Polish coking coals. Proximate analysis, free swelling index, Ruhr dilatometer and Gieseler plastometer were...Two Nigerian coals, Lafia-Obi and Chikila were blended in the mass ratio of 70:30 with imported American and Polish coking coals. Proximate analysis, free swelling index, Ruhr dilatometer and Gieseler plastometer were used in assessing the coking qualities of both the single coals and the blends. The results show that the blends are lower in moisture and ash contents;higher in volatile matter and fixed carbon than the single Nigerian coals. The rheological parameters revealed superiority in thermo-plastic properties of the blends over the unblended local coals. Lafia-Obi/Foreign coals blends possess lower ash and better rheological properties compared to Chikila/Foreign coal composites which have high ash and poor rheological properties. These together suggest that amongst the two Nigerian coals, Lafia-Obi is superior for blending with the foreign ones in metallurgical coke production.展开更多
Tars from two Mongolian coals (Tavan Tolgoi and Baganuur) produced by simple distillation have been characterized using size exclusion chromatography (SEC) with elution in both 1-methyl-2-pyrrolidinone (NMP) and a mix...Tars from two Mongolian coals (Tavan Tolgoi and Baganuur) produced by simple distillation have been characterized using size exclusion chromatography (SEC) with elution in both 1-methyl-2-pyrrolidinone (NMP) and a mixed solvent (NMP and chloroform), UV-fluorescence in chloroform and NMP, gas chromatography (GC), mass spectrometry (GC-MS, probe-MS and LD-MS with thin layer chromatography) and infra-red spectroscopy. The SEC chromatograms using NMP and the solvent mixture NMP: chloroform indicates that similar conclusions can be drawn from using either eluent. The synchronous UV-fluorescence spectra were shifted to longer wavelengths in chloroform solution than in NMP and chloroform may be the better solvent for these tars prepared without extensive secondary thermal treatment. Infra-red spectra indicated differences between the two coal tars that reflected their different ranks, with more oxygenate groups in the lower rank Baganuur coal. Mass spectrometry (GC-MS and probe-MS) of both coal tars confirmed the presence of aliphatic components as well as aromatics and the relatively extensive alkylation of aromatics. Molecular mass ranges indicated for Baganuur tar by SEC compared well with the mass range by LD-MS although the LD-MS extended to higher mass values. The high mass fractions of the tars were revealed by fractionation by thin layer chromatography with the relevant sections of the developed plates inserted directly into the mass spectrometer;laser desorption was directly from the surface of the plate. LD-MS of the unfractionated samples failed to detect the high mass components because of mass discrimination effects. The high mass components were carried over in the distillation by mass transfer of vapours into the condenser.展开更多
The deformation of coal is effected by thermal effect, pressures and tectonic stress, and the tectonic stress is the principal influence factor. However, the proposition of a useful quantitative index that responds to...The deformation of coal is effected by thermal effect, pressures and tectonic stress, and the tectonic stress is the principal influence factor. However, the proposition of a useful quantitative index that responds to the degree of deformation of coals quantitatively or semi-quantitatively has been a long-debated issue. The vitrinite reflectance ellipsoid, that is, the reflectance indication surface（RIS） ellipsoid is considered to be a strain ellipsoid that reflects the sum of the strain increment caused by stress in the process of coalification. It has been used to describe the degree of deformation of the coal, but the effect of the anisotropy on the RIS ellipsoid has not yet been considered with regards to non-structural factors. In this paper, Wei＇s parameter（ε） is proposed to express the deformation degree of the strain ellipsoid based on considering the combined influence of thermal effect, pressure and tectonic stress. The equation is as follows： ε=√[（ε_1-ε_0）~2＋（ε_2-ε_0）~2＋（ε_3-ε_0）~2]/3, where ε_1=lnR_（max）, ε_2=lnR_（int）, ε_3=lnR_（min）, and ε_0=（ε_1＋ε_2＋ε_3）/3. Wei＇s parameter represents the distance from the surface to the spindle of the RIS logarithm ellipsoid; thus, the degree of deformation of the strain ellipsoid is indicated quantitatively. The formula itself, meanwhile, represents the absolute value of the degree of relative deformation and is consequently suitable for any type of deformation of the strain ellipsoid. Wei＇s parameter makes it possible to compare degrees of deformation among different deformation types of the strain ellipsoid. This equation has been tested in four types of coal： highly metamorphic but weakly deformed coal of the southern Qinshui Basin, highly metamorphic and strongly deformed coal from the Tianhushan coal mining area of Fujian, and medium metamorphic and weakly or strongly deformed coal from the Huaibei Coalfield. The results of Wei＇s parameters are consistent with the actual deformation degrees of the coal reservoirs determined by other methods, which supports the effectiveness of this method. In addition, Wei＇s parameter is an important complement to the indicators of the degrees of deformation of coals, which possess certain theoretical significance and practical values.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42102223)the Chinese Postdoctoral Science Foundation(Grant Nos.2021M693844,2022T150284)+1 种基金the Chinese Geological Survey Project(Grant No.DD20160204-3)the discipline innovation team of Liaoning Technical University(Grant Nos.LNTU20TD-14,LNTU20TD-30)。
文摘Coal pore parameters are closely related to macrolithotypes and coal structures,having a large influence over the gas potential and productivity of coalbed methane(CBM).The Middle Jurassic Xishanyao Formation,located in the southern Junggar Basin of northwestern China,has geological conditions with rich CBM resources.The 46 Xishanyao coal samples gathered from the drilling cores and coal mines cover 4 types of macrolithotypes(bright coal 1,semi-bright coal 2,semi-dull coal 3,and dull coal 4)and 2 types of coal structures(primary coal I and cataclastic coal II).Based on a range of pore testing experiments and analytical methods,the dual effects of different macrolithotypes and coal structures on pore structures were intensely studied.The results showed that the specific surface area(SSA)and total pore volume(TPV)of coal samples increased gradually from bright to dull coals.For the same macrolithotypes,the SSA and TPV of the primary coals were lower than those of the cataclastic coals.Generally,the pore structures of bright and semi-bright coals are simpler when compared to semi-dull and dull coals with the same coal structure,whereas cataclastic coals have more complicated pore structure systems than primary coals with the same macrolithotypes.The bright and semi-bright coals have higher vitrinite contents and more endogenous fractures,whereas well-developed structural fractures were identified in cataclastic coals.Therefore,bright and semi-bright coals have better pore connectivity than semi-dull and dull coals with the same coal structure,the pore connectivity of cataclastic coals being slightly better than that of primary coals under the same macrolithotypes.In terms of the CBM adsorption conditions,the eight type samples formed a descending order:Ⅱ-4>I-4>Ⅱ-3>Ⅰ-3>Ⅱ-2>Ⅰ-2>Ⅱ-1>Ⅰ-1,while they ranked as follows when consideration was given to the CBM seepage capacities:II-2>Ⅱ-1>Ⅰ-2>Ⅰ-1>Ⅰ-3>Ⅰ-4>Ⅱ-3>Ⅱ-4.As a result,it could be determined that the bright and semi-bright coals had stronger adsorption capacities,whereas the cataclastic coals had better pore connectivity and seepage capacities.Pore structure characteristics should be analysed under the dual control of different macrolithotypes and coal structures,so that they can provide greater value for guiding CBM exploration and exploitation,as along for preventing underground gas accidents.
基金supported by the Key Project of Chongqing Special Program for Technological Innovation and Application Development(CSTB2024TIAD-KPX0099)the Graduate Research Innovation Project of Chongqing,China(CYB240050),the Fundamental Research Funds for the Central Universities(2025CDJZKKYJH-14)the State Key Laboratory of Coal Mine Disaster Dynamics and Control for 2030 major project(2011DA105287-MX2030-202101).
文摘Gas injection-enhanced underground coal combustion for heat extraction represents a disruptive chemical fluidized extraction method of coal resources.Coal seam combustion dynamics provide crucial underpinnings for engineering realization.This study establishes an experimental system for monitoring temperature field evolution during gas-assisted combustion in cylindrical coal cores,investigating the influence of moisture content(0%,16%,24%)on gas-assisted combustion kinetics.Results showed moisture content significantly influences combustion:higher levels(16%-24%)delay high-temperature expansion(0-1 h)due to evaporation energy absorption,but subsequently enhance efficiency through pore formation and oxygen diffusion,achieving 1120-1230°C peaks.Dry coal exhibits rapid initial combustion(peak temperature of 1130°C within 1 h)but weaker sustained reactions.The temperature field evolves from localized hotspots to an elliptical high-temperature zone,with axial expansion rates surpassing radial rates,driven by thermal buoyancy and convective heat transfer.Moisture’s dual role is revealed:initially as a thermodynamic inhibitor and later as a promoter by increasing pore diameter and oxygen diffusion coefficients.An optimal moisture content of 16%balances initial heat loss with enhanced reactivity,offering practical insights for optimizing gas injection and thermal recovery in underground coal combustion.
基金funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan(Grant No.AP13067779)。
文摘This research presents the results of a comprehensive study of mineralogical and geochemical features of REE distribution in coals of Central Kazakhstan deposits—Karaganda coal basin and Shubarkol deposit,which have large hard coal reserves and are industrially important for the coal industry of Kazakhstan;the research is based on 205 samples of clayey interlayers and coal seams.It shows basic patterns of distribution and features of concentration for impurity elements,gives an estimate of the impurity elements concentration,including REE,defines conditions and factors of their accumulation,and studies features of their forms in coal and coal-bearing rocks,which allows estimating the mechanisms of their migration and conditions of accumulation.According to the results of geochemical indicators,the article establishes the factors of REE dislocation,reveals the composition of margin rocks that have influenced REE concentration in coal seams,and the presented latest data on mineralogy allowed to establish the ways of their transportation to the paleobasin during the synand epigenetic periods of formation of the coal deposits of Central Kazakhstan being researched.It was found that the coals are insignificantly enriched with heavy lanthanides from Ho to Lu.The distribution curves of UCC normalized REE values in the coals are similar and coincide,but they are less than the average value for world coal,and amount to only one-third of the UCC.It was found that the highest concentrations of all REE are characteristic of clayey interlayers and oxidized coals.The La/Yb ratio in this case increases upwards along the section,indicating mainly clastogenic mechanism of REE delivery to the coals.In coal and clay samples,the predominant mineral form of REE is light lanthanide phosphates.Identified particles of REE from minerals and their composition peculiarities suppose autigene nature of their formation.The formation of the bulk of autigene minerals occurred during the maturation of brown coals and their transformation into hard ones.
基金supported by the National Natural Science Foundation of China(42272202 and 52264001)the Yunnan Fundamental Research Projects(202201AT070144)+1 种基金the Yunnan Ten Thousand Talents Plan Young&Elite Talents Project(YNWRQNBJ-2019-164)Training Programmes of Innovation and Entrepreneurship for Undergraduates of Yunnan Province(S202210674128).
文摘In order to comprehend the applicability of microwave irradiation for recovering coalbed methane,it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism.In this work,the carbon molecular sieve combined with KMnO_(4)oxidation was selected to fabricate carbon molecular sieve with diverse oxidation degrees,which can serve as model substances toward coals.Afterwards,the microwave irradiation dependences of pores,functional groups,and highpressure methane adsorption characteristics of model substances were studied.The results indicated that microwave irradiation causes rearrangement of oxygen-containing functional groups,which could block the micropores with a size of 0.40-0.60 nm in carbon molecular sieve;meanwhile,naphthalene and phenanthrene generated by macro-molecular structure pyrolysis due to microwave irradiation could block the micropores with a size of 0.70-0.90 nm.These alterations in micropore structure weaken the saturated methane adsorption capacity of oxidized carbon molecular sieve by 2.91%-23.28%,suggesting that microwave irradiation could promote methane desorption.Moreover,the increased mesopores found for oxidized carbon molecular sieve after microwave irradiation could benefit CH4 diffusion.In summary,the oxidized carbon molecular sieve can act as model substances toward coals with different ranks.Additionally,microwave irradiation is a promising technology to enhance coalbed methane recovery.
基金provided by the China Scholarship Council(No.202006430006)and the University of Wollongongsupported by the ACARP Projects(Nos.C28006 and C35015)support from the Coal Services Health and Safety Trust(No.20661)。
文摘Methane(CH_(4))and carbon dioxide(CO_(2))are primary components of coal seam gas(CSG).Understanding their adsorption-desorption hysteresis characteristics,along with the fundamental mechanism,is crucial for CSG exploitation and related hazards mitigation.This research focused on the representative Bulli coal seam in the Sydney Basin,Australia.Through the purpose-built indirect gravimetric high-pressure isothermal adsorption-desorption hysteresis experiment,a novel Langmuir-based desorption model,incorporating hysteresis effect and residual gas,was proposed.Quantitative characterization of the adsorption-desorption hysteresis degrees of CO_(2)and CH_(4)i n coal particles of various sizes and inΦ50mm 100 mm intact coal samples were achieved using the improved hysteresis index(IHI).The experimental findings validated that the proposed desorption model accurately describes the desorption behavior of CO_(2)and CH_(4)in coal(R^(2)>0.99).Based on the adsorption-desorption properties of inkbottle-shaped micropores and pore deformation caused by gas adsorption-induced coal expansion,the occurrence mechanism of adsorption–desorption hysteresis and the fundamental reasons for the presence of residual gas were elucidated.Furthermore,the study explored the impact of CO_(2)and CH_(4)adsorption-desorption hysteresis effects on coal and gas outbursts,suggesting that coal seams rich in CO_(2)do not have a higher propensity for outbursts than those rich in CH_(4).
基金Lanre Asiwaju received a scholarship for doctorate study from the Nigerian Government through the Petroleum Technology Development Fund(PTDF).
文摘Forty Tertiary coals from Mukah-Balingian and Merit-Pila coalfields of the Sarawak Basin,Malaysia were investigated using bulk and molecular geochemical techniques such as proximate analysis,gas chromatography-mass spectrometry,elemental analyser,isotope ratio mass spectrometry,and inductively coupled plasma mass spectrometry to reconstruct their paleovegetation,paleoclimate,and environments of deposition.In addition,principal component analysis(PCA)of selected geochemical parameters was carried out to determine the controlling influences on the petroleum potential of the humic coals.s13C values and the abundance of terpenoids imply the predominant contribution of angiosperms to the paleoflora.Bimetal proxies(Sr/Ba,Sr/Cu,and C-value),andδD values are generally suggestive of a warm and humid climate during the accumulation of the paleopeats.However,n-alkane proxies(P_(wax),P_(aq),n-C_(23)/n-C_(29),etc.)and polycyclic aromatic hydrocarbons(PAHs)distribution suggest that Balingian coals accumulated under relatively drier and strongly seasonal palcoclimate in the Late Pliocene.When compared with published global average abundances,the investigated coals are mostly depleted in major oxides and trace elements,suggesting peat accumulation in freshwater-influenced environments.Nonetheless,higher(>0.5 wt%)total sulfur content in some Mukah-Balingian coals suggests some degree of epigenetic marine influence.Fur-thermore,the low to moderately-high ash contents of the Sarawak Basin coals indicate the presence of ombrotrophic and rheotrophic peat deposits.PCA result of selected geochemical proxies suggests that source input,paleoflora,and marine incursions are not major controlling influences on the petroleum potential.However,climatic,and depositional conditions appear to slightly influence the petroleum potential of the studied humic coals.
基金supported by the National Natural Science Foundation of China(52304311 and 52274282)Yue Qi Young Scholar Project,China University of Mining&Technology,Beijing(2020QN10).
文摘Special attention was drawn to the heavy metals contained in coal,due to it will cause harm to the environment during coal processing and utilization.The sequential chemical extraction of Shanxi coal(SX coal)and Wulanchabu coal(WLCB coal)was carried out to investigate the distribution of arsenic(As)in coals.Two raw coals were pyrolyzed at 300-900℃ in horizontal tubular furnace to investigate release behavior of As during pyrolysis process.The results showed that As in SX coal mainly existed in aluminosilicate-bound state(40.25%)and disulfide-bound state(32.51%),followed by carbonate-bound state and organic-bound state.The As in WLCB coal mainly existed in aluminosilicate-bound state(62.50%),followed by disulfide-bound state(19.10%).The As contents of water-soluble,ion-exchange and residue states in the two coals were less than others.The modes of occurrence of As had great infuence on its volatilization behavior.As in organic part was easy to volatilize at low temperature.Sulfide-bound state would escape with the decomposition of pyrite.Because SX coal contained higher organic state and sulfide-bound state,the volatilization rate of As was higher than WLCB coal at any temperature,and the difference was more obvious at low temperature.In addition,FactSage simulation value was basically consistent with the experimental value.
文摘Solvent-extracted fractions of six Indian coal samples of different ranks were investigated using multiple geochemical,petrological and spectroscopic proxies and an attempt was made to indicate possible fingerprint regions for different polycyclic aromatic hydrocarbons(PAH)with the help of excitation-emission matrix(EEM).In this study,for the very first time,the influence of rank and maturation of organic matter in the characterisation of coal solvent-extracts from Indian coals were perceived from the viewpoint of fluorescence EEM.Vitrinite reflectance(VR_(0))values were used to determine the general ranks of the original coal samples viz.lignite,subbituminous,bituminous and anthracite.Different fluorescence peak regions corresponding to different fused aromatic ring(FAR)systems were delineated using the EEM and their indicative depositional environments could be inferred.Our observations indicate that solvent-extracted fractions of low rank coals comprise of a larger number of shorter carbon chains compared to the other samples.For the low rank coal samples,the solvent-extracts show a strong humic influence and the presence of smaller PAH rings while for the medium rank coals,the extracted fractions tend to show a more bimodal distribution of PAHs,possibly comprising of different sized PAHs.Higher fluorescence sensitivity and quick response of smaller PAHs impart a singular centralised region in the EEM for the low rank coal samples while interference in the fluorescence of differently sized PAHs indicate a multimodal distribution of the fluorophores in the medium rank coals.The high rank coal used in this study shows a bimodal distribution with very low intensity of the peaks,indicating the low abundance of extractable macromolecules,possibly as a result of deformation.
基金financed by the REGALOR project(Ressources Gazieres de Lorraine).
文摘The enhanced coalbed methane recovery using CO_(2) injection(CO_(2)-ECBM)is widely proposed as a way of achieving the energy transition and reducing atmospheric CO_(2),in areas such as the Lorrain basin in France,where heavy industry is responsible for huge CO_(2) emissions and coal mines have been closed for more than a decade.This paper deals with the feasibility of extracting methane from the Lorraine basin using CO_(2)-ECBM by comparing data from sorption isotherms,thermogravimetric analyses and breakthrough curves for two coal samples.One is bituminous(Box 18),from Folschviller(France)and is compared with another sub-bituminous(THO1)from La Houve(France),which is used as a reference because it was identified as a good candidate for CO_(2)-ECBM in a previous research program.The quantities of adsorbed gases(CO_(2)/CH_(4))obtained by sorption isotherms,thermogravimetry and CO,breakthrough curves showed that Box 18 adsorbs more CO_(2) and CH_(4) than THO1 due to its higher porosity and good affinity for gases(CO_(2)/CH_(4)).Toth model fits the experimental CH_(4) and CO_(2) adsorption isotherms better,reflecting the fact that the adsorption surface of the coals studied is heterogeneous.Adsorption enthalpies obtained by calorimetry indicated physisorption for gas-coal interactions,with higher values for CO_(2) than for CH_(4).Thermogravimetric analyses and breakthrough curves carried out at up to 50%relative humidity showed that the adsorption capacity of CO_(2) decreases with increasing temperature and the presence of water,respectively.The compilation of these experimental data explained the adsorption process of the studied coals and revealed their advantages for CO_(2)-ECBM.
文摘Coal has been used as an energy resource around the world, primarily for the generation of electricity. The cleaning of coal by removing its unwanted sulfur and mineral matter components is utmost essential before their gainful utilizations. The ionic liquids （ILs） are considered as non-toxic solvents for using in different industrial processes. The effect of two ILs namely, 1-n-butyl, 3-methylimidazolium tetrafluoro borate （ILl） and 1-n-butyl, 3-methylimidazolium chloride （IL2） in oxidative de-sulfurization and de-ashing of two industrially important high sulfur coal samples from Meghalaya （India） is discussed in this paper. The maximum removal of total sulfur, pyritic sulfur, sulfate sulfur and organic sulfur are observed to be 37.36 %, 62.50 %, 83.33 % and 31.63 % respectively during this oxidative process. The quantitative diffuse reflectance Fourier transform-infrared spectroscopy analysis supports the formation of sulfoxides （S--O） and sulfones （-SO2） and their subsequent removal during the oxidation of the coals in presence of ILs. The X-ray fluorescence combined with near edge X-ray absorption fine structure and scanning electron microscopic studies reveal the removal of mineral matters （ash yields） from the coal samples. The thermogravimetric analysis of the raw and clean coals indicates their high combustion efficiencies and suitability for using in thermal plants. The method is partially green and the ILs could be recovered and reused in the process.
基金supported by the National Natural Science Foundation of China(Grant No.40772135,4097213141030422)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05030100)National Science and Technology Major Project(No.2011ZX05060-005).
文摘The macromolecular structure of tectonically deformed coals(TDC)may be determined by the deformation mechanisms of coal.Alterations of the macromolecular structure change the pore structure of TDC and thereby impact physical properties such as porosity and permeability.This study focuses on structure and properties of TDC from the Huaibei and Huainan coal mining areas of southern North China.Relationships between the macromolecular structure and the pore structure of TDC were analyzed using techniques such as X-ray diffraction,high-resolution transmission electron microcopy,and the low-temperature nitrogen adsorption.The results indicated that the directional stress condition can cause the arrangement of basic structural units(BSU)more serious and closer.And,the orientation is stronger in ductile deformed coal than in brittle deformed coal.Tectonic deformation directly influences the macromolecular structure of coal and consequently results in dynamic metamorphism.Because the size of BSU in brittle deformed coal increases more slowly than in ductile deformed coal,frictional heating and stress-chemistry of shearing areas might play a more important role,locally altering coal structure under stress,in brittle deformed coal.Strain energy is more significant in increasing the ductile deformation of coal.Furthermore,mesopores account for larger percentage of the nano-scale pore volume in brittle deformed coals,while mesopores volume in ductile deformed coal diminishes rapidly along with an increase in the proportion of micropores and sub-micropores.This research also approved that the deformations of macromolecular structures change nano-scale pore structures,which are very important for gas adsorption and pervasion space for gas.Therefore,the exploration and development potential of coal bed methane is promising for reservoirs that are subjected to a certain degree of brittle deformation(such as schistose structure coal,mortar structure coal and cataclastic structure coal).It also holds promise for TDC resulting from wrinkle structure coal of low ductile deformation and later superimposed by brittle deformation.Other kinds of TDC suffering from strong brittle-ductile and ductile deformation,such as scale structure coal and mylonitic structure coal,are difficult problems to resolve.
文摘The use of high As-bearing coals has caused more than 3,000 cases of arsenosis patients in southwest Guizhou Province, China. The mode of occurrence of arsenic in coal is an important key role in understanding its behavior during usage and damage pathway to human health. Coal samples from endemic arsenosis areas were analyzed with INAA, EMPA, SEM-EDX, LTA, XRD, XAFS, and sequential leaching experiment. Arsenic in pyrite is from under the limit of EMPA to 1.75%, and in most cases, the content of arsenic is lower than 0.5%. Besides pyrite and arsenopyrite, SEM-EDX combined with LTA and XRD find that sulfates, clay and phosphates also contain arsenic. XAFS shows that arsenic mainly exists in the form of As^5＋. More than 50% of arsenic stayes in residual solid and combined with organic matrix in two samples, but most arsenic is leached out in other samples. The occurrence of such exceptionally high As contents in coal and the fact that the arsenic is dominantly organically associated are unique observations.
基金This research was supported by the National Key Basic Research and Development Program(No.2014CB238902)National Natural Science Foundation of China(Nos.41272182 and 40930420)the Program for Changjiang Scholars and Innovative Research Team in University.
文摘Minerals in the Late Permian coals from the Niuchang-Yigu mining area,Zhenxiong County,northeastern Yunnan,China,were investigated using optical microscopy and low temperature ashing plus X-ray diffraction(LTA?XRD).The results showed that minerals in the coal LTAs are mainly quartz,kaolinite,chamosite,mixed-layer illite/smectite(I/S),pyrite,and calcite,with trace amounts of marcasite,dolomite,and bassanite.The authigenic quartz generally occurs in collodetrinite or as a filling in cleats or cell cavities.This silica was mainly derived from aqueous solutions produced by the weathering of basaltic rocks in the Kangdian Upland and from hydrothermal fluids.The presence of b-quartz paramorph grains in collodetrinite probably indicates that these grains were detrital and came from a volcanic ash.Clay minerals are generally embedded in collodetrinite and occur as cell-fillings.Pyrite occurs as framboidal,anhedral,and euhedral grains and a cell-filling.The coals are high in pyrite and the high pyrite content probably results from seawater invading during the stage of peat accumulation.Calcite generally occurs as vein-fillings,indicating an epigenetic origin.
文摘In this study,the physicochemical,microstructural,mineralogical,thermal,and kinetic properties of three newly discovered coals from Akunza(AKZ),Ome(OME),and Shiga(SHG)in Nigeria were examined for potential energy recovery.Physicochemical analysis revealed high combustible but low levels of polluting elements.The higher heating values ranged from 18.65 MJ/kg(AKZ)to 26.59 MJ/kg(SHG).Microstructure and mineralogical analyses revealed particles with a rough texture,surface,and glassy lustre,which could be ascribed to metals,quartz,and kaolinite minerals.The major elements(C,O,Si,and Al),along with minor elements(Ca,Cu,Fe,K,Mg,S,and Ti)detected are associated with clays,salts,or the porphyrin constituents of coal.Thermal analysis showed mass loss(ML)ranges from 30.51%to 87.57%and residual mass(RM)from 12.44%to 69.49%under combustion(oxidative)and pyrolysis(non-oxidative)TGA conditions due to thermal degradation of organic matter and macerals(vitrinite,inertinite and liptinite).Kinetic analysis revealed the coals are highly reactive under the oxidative and non-oxidative conditions based on the Coats-Redfem Model.The activation energy(Ea)ranged from 23.81 to 89.56 kJ/mol,whereas the pre-exponential factor(kQ)was from 6.77×10^(-4)/min to 1.72×10^(3)/min under pyrolysis and combustion conditions.In conclusion,the coals are practical feedstocks for either energy recovery or industrial applications.
基金The authors Sreedevi Upadhyayula acknowledges funding(Grant No.TMD/CERI/MDME/2017/001(G))from the Department of Science and Technology,New Delhi,India.Dr.Heena Dhawan is thankful to Prof.D.K.Sharma,Retired Professor of Centre for Energy Studies,IIT Delhi for his help with the coal samples and continuous guidance through the work and Prof.M.Crocker and T.Morgan,Center for Applied Energy Research,University of Kentucky,Lexington,KY 40511,USA for the Py-GCMS analysis.
文摘The present work aims at studying five Indian coals and their solvent extracted clean coal products using Py-GCMS analysis and correlating the characterization data using theoretical principal component analysis.The pyrolysis products of the original coals and the super clean coals were classified as mono-,di-and tri-aromatics,while other prominent products that were obtained included cycloalkanes,n-alkanes,and alkenes ranging from C_(10)-C_(29).The principal component analysis is a dimensionality reduction technique that reduced the number of input variables in the characterization dataset and gave inferences on the relative composition of constituent compounds and functional groups and structural insights based on scores and loading plots which were consistent with the experimental observations.ATR-FTIR studies confirmed the reduced concentration of ash in the super clean coals and the presence of aromatics.The Py-GCMS data and the ATR-FTIR spectra led to the conclusion that the super clean coals behaved similarly for both coking and noncoking coals with high aromatic concentrations as compared to the raw coal.Neyveli lignite super clean coal was found to show some structural similarity with the original coals,whereas the other super clean coals showed structural similarity within themselves but not with their original coal samples confirming the selective action of the e,N solvent in solubilizing the polycondensed aromatic structures in the coal samples.
基金supported by the National Natural Science Foundation of China(grants No.41373108 and 41602167)
文摘Igneous intrusion into coal-bearing strata can cause an abrupt increase of temperature-pressure and trigger hydrothermal circulation at the igneous rock-coal contact zone. The conductive heat of intruded lnagma and convective migration of secondary hydrothermal fluids have been observed to significantly alter the concentrations and modes of occurrence of mercury （Hg） in thermally-intruded coals.
文摘The analyses of different sulfur forms, the trace elements in pyrites using electron microprobe and the trace elements in coal using INAA (instrumental neutron activation analysis) of the Late Paleozoic coals from the Taozao coalfield in Shandong Province, China, conclude that most sulfur (>75 %) in high-sulfur coal of Taiyuan Formation occurred as pyrite, in which many hazardous elements co-existed and their concentrations varied with their geological origin. The concentrations of hazardous elements in high-sulfur coals from Taiyuan Formation, composing mainly of Cu, As, U, Pb, Mo and Co, are much higher than those in the low-sulfur coals from Shanxi Formation and Shihezi Formation, because the influence of seawater during and after coal accumulation in Taiyuan Formation is stronger than those in Shanxi and Shihezi formations. Moreover, the element As is related to Fe, and both elements exist mainly in the form of pyrite. The element U is richer in the coal influenced by seawater. In addition, the coal affected by the magmatism contains more U, too. When high-sulfur coals are processed with heavy media washing to remove sulfur and minerals, the majority of hazardous elements will also be removed from the coals.
文摘Two Nigerian coals, Lafia-Obi and Chikila were blended in the mass ratio of 70:30 with imported American and Polish coking coals. Proximate analysis, free swelling index, Ruhr dilatometer and Gieseler plastometer were used in assessing the coking qualities of both the single coals and the blends. The results show that the blends are lower in moisture and ash contents;higher in volatile matter and fixed carbon than the single Nigerian coals. The rheological parameters revealed superiority in thermo-plastic properties of the blends over the unblended local coals. Lafia-Obi/Foreign coals blends possess lower ash and better rheological properties compared to Chikila/Foreign coal composites which have high ash and poor rheological properties. These together suggest that amongst the two Nigerian coals, Lafia-Obi is superior for blending with the foreign ones in metallurgical coke production.
文摘Tars from two Mongolian coals (Tavan Tolgoi and Baganuur) produced by simple distillation have been characterized using size exclusion chromatography (SEC) with elution in both 1-methyl-2-pyrrolidinone (NMP) and a mixed solvent (NMP and chloroform), UV-fluorescence in chloroform and NMP, gas chromatography (GC), mass spectrometry (GC-MS, probe-MS and LD-MS with thin layer chromatography) and infra-red spectroscopy. The SEC chromatograms using NMP and the solvent mixture NMP: chloroform indicates that similar conclusions can be drawn from using either eluent. The synchronous UV-fluorescence spectra were shifted to longer wavelengths in chloroform solution than in NMP and chloroform may be the better solvent for these tars prepared without extensive secondary thermal treatment. Infra-red spectra indicated differences between the two coal tars that reflected their different ranks, with more oxygenate groups in the lower rank Baganuur coal. Mass spectrometry (GC-MS and probe-MS) of both coal tars confirmed the presence of aliphatic components as well as aromatics and the relatively extensive alkylation of aromatics. Molecular mass ranges indicated for Baganuur tar by SEC compared well with the mass range by LD-MS although the LD-MS extended to higher mass values. The high mass fractions of the tars were revealed by fractionation by thin layer chromatography with the relevant sections of the developed plates inserted directly into the mass spectrometer;laser desorption was directly from the surface of the plate. LD-MS of the unfractionated samples failed to detect the high mass components because of mass discrimination effects. The high mass components were carried over in the distillation by mass transfer of vapours into the condenser.
基金financial supported by National Natural Science Foundation of China(Nos.41372213,41030422)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA05030100)
文摘The deformation of coal is effected by thermal effect, pressures and tectonic stress, and the tectonic stress is the principal influence factor. However, the proposition of a useful quantitative index that responds to the degree of deformation of coals quantitatively or semi-quantitatively has been a long-debated issue. The vitrinite reflectance ellipsoid, that is, the reflectance indication surface（RIS） ellipsoid is considered to be a strain ellipsoid that reflects the sum of the strain increment caused by stress in the process of coalification. It has been used to describe the degree of deformation of the coal, but the effect of the anisotropy on the RIS ellipsoid has not yet been considered with regards to non-structural factors. In this paper, Wei＇s parameter（ε） is proposed to express the deformation degree of the strain ellipsoid based on considering the combined influence of thermal effect, pressure and tectonic stress. The equation is as follows： ε=√[（ε_1-ε_0）~2＋（ε_2-ε_0）~2＋（ε_3-ε_0）~2]/3, where ε_1=lnR_（max）, ε_2=lnR_（int）, ε_3=lnR_（min）, and ε_0=（ε_1＋ε_2＋ε_3）/3. Wei＇s parameter represents the distance from the surface to the spindle of the RIS logarithm ellipsoid; thus, the degree of deformation of the strain ellipsoid is indicated quantitatively. The formula itself, meanwhile, represents the absolute value of the degree of relative deformation and is consequently suitable for any type of deformation of the strain ellipsoid. Wei＇s parameter makes it possible to compare degrees of deformation among different deformation types of the strain ellipsoid. This equation has been tested in four types of coal： highly metamorphic but weakly deformed coal of the southern Qinshui Basin, highly metamorphic and strongly deformed coal from the Tianhushan coal mining area of Fujian, and medium metamorphic and weakly or strongly deformed coal from the Huaibei Coalfield. The results of Wei＇s parameters are consistent with the actual deformation degrees of the coal reservoirs determined by other methods, which supports the effectiveness of this method. In addition, Wei＇s parameter is an important complement to the indicators of the degrees of deformation of coals, which possess certain theoretical significance and practical values.
