Desulfurization kinetics of ZnO sorbent loaded on semi-coke support for hot coal gas

Zn-based sorbent （Z20SC） prepared through semi-coke support in 20 wt% zinc nitrate solution by high-pressure impregnation presents an excellent desulfurization capacity in hot coal gas,in which H2 S can not be nearly detected in the outlet gas before 20 h breakthrough time.The effects of the main operational conditions and the particle size of Z20SC sorbent on its desulfurization performances sorbent were investigated in a fixed-bed reactor and the desulfurization kinetics of Z20SC sorbent removing H2 S from hot coal gas was calculated based on experimental data.Results showed that the conversion of Z20SC sorbent desulfurization reaction increased with the decrease of the particle size of the sorbent and the increases of gas volumetric flow rate,reaction temperature and H 2 S content in inlet gas.Z20SC sorbent obtained from hydrothermal synthesis by high-pressure impregnation possessed much larger surface area and pore volume than semi-coke support,and they were significantly reduced after the desulfurization reaction.The equivalent grain model was reasonably used to analyze experimental data,in which k s=4.382×10-3 exp（-8.270×103/RgT） and Dep=1.262×10-4exp（1.522×104/RgT）.It suggests that the desulfurization reaction of the Z20SC sorbent is mainly controlled by the chemical reaction in the initial stage and later by the diffusion through the reacted sorbent layer.

Effects of ultrasound on the desulfurization performance of hot coal gas over Zn-Mn-Cu supported on semi-coke sorbent prepared by high-pressure impregnation method

Zn-Mn-Cu/SC（U） sorbent was hydrothermally synthesized by ultrasound-assisted high-pressure impregnation method with semi-coke（SC）as support and the mixed solution of zinc nitrate,manganese nitrate and copper nitrate as active component precursors.The desulfurization performances of hot coal gas on the prepared sorbent at a mid-temperature of 500°C were tested in fixed-bed reactor.Morphology and pore structure of the prepared sorbent were also characterized by TEM,N2adsorption/desorption isotherms and XRD.For comparison,the sorbent of Zn-Mn-Cu/SC prepared by conventional high-pressure impregnation was also evaluated and characterized in order to study the effects of ultrasound treatment.Zn-Mn-Cu/SC（U） sorbent prepared by high-pressure impregnation under ultrasound-assisted condition showed a better desulfurization performance than Zn-Mn-Cu/SC.It could remove H2 S from 1000×10-6m3/m3 to 0.1×10-6m3/m3 at 500°C and maintained for 12.5 h with the sulfur capacity of 7.74%,in which both the breakthrough time and sulfur capacity were about 32% and 51% higher than those of Zn-Mn-Cu/SC sorbent.The introduction of ultrasound during high-pressure impregnation process greatly improved the morphology and pore structure of the sorbent.The ultrasonic treatment made particle size of active components smaller and made them more evenly disperse on semi-coke support,which provided more opportunities to contact with H2S in coal-based gases.However,there were no any difference in compositions and existing forms of active components on the Zn-Mn-Cu/SC and Zn-Mn-Cu/SC（U） sorbents.

Characterization of semi-coke generated by coal-based direct reduction process of siderite

Solid wastes derived from metallurgical industries pose a significant threat to environment. The utilization and disposal of these solid wastes are the major concern in the world. Semi-coke generated in coal-based direct reduction process of iron ore is a by-product and its suitable utilization is not available so far. In order to handle it properly, the characteristics of this by-product were comprehensively investigated. A series of analysis methods were used to demonstrate its mineral compositions, petrography and physico-chemical properties. The results reveal that the semi-coke has poor washability. The fixed carbon content of semi-coke reaches 76.11% and the gross calorific value is 28.10 MJ/kg, both of which are similar to those of traditional sinter coke breeze. Also, semi-coke ash possesses lower content of SiO2, Al2O3, S and higher content of CaO and MgO, which could improve the strength of sinter ore when partially substituting for coke breeze in sintering. Semi-coke features well-development porous structure and higher reaction activity, which predicts that the sintering speed could be elevated to some extent when employing it as a partial replacement of coke breeze, so the studies further suggest that the potential adverse effect of the high reactivity on sintering process could be weakened by adequately coarsening the semi-coke's particle size.

Impact of impregnation pressure on desulfurization performance of Zn-based sorbents supported on semi-coke

High-pressure impregnation, a new preparation method for sorbents to remove H2S from hot coal gas, is introduced in this paper. Semi-coke （SC） and ZnO is selected as the support and active component of sorbent, respectively. The sorbent preparation process includes high-pressure impregnation, filtration, ovendry and calcination. The aim of this research is to primarily study the effects of the impregnation pressure on physical properties and desulfurization ability of the sorbent. The desulfurization experiment was carried out in a fixed-bed reactor at 500 ~C and a simulated coal gas used in this work was composed of CO （33 vol%）, H2 （39 vol%）, H2S （300 ppm in volume）, and N2 （balance）. Experimental results show that the pore structure of the SC support can be improved effectively and ZnO active component can be uniformly dispersed on the support, with the small particle size of 10-500 nm. Sorbents prepared using high-pressure impregnation have better desulfurization capacity and their active components have higher utilization rate. P20-ZnSC sorbent, obtained by high-pressure impregnation at 20 atm, has the best desulfurization ability with a sulfur capacity of 7.54 g S/100g sorbent and a breakthrough time of 44 h. Its desulfurization precision and efficiency of removing H2S from the middle temperature gases can reach 〈 1 ppm and 〉99.7%, respectively, before sorbent breakthrough.

Investigation on activated semi-coke desulfurization

An activated semi coke with industrial scale size was prepared by high pressure hydrothermal chemistry activation, HNO 3 oxidation and calcination activation in proper order from Inner Mongolia Zhalainuoer semi coke, which is rich in resource and cheap in sale. SO 2 adsorption capacity on this activated semi coke was assessed in the fixed bed in the temperature range of 60—170℃, space velocity range of 500—1300 h -1 , SO 2 concentration of 1000—3000 ppmv, and N 2 as balance. The surface area, elemental and proximate analysis for both raw semi coke and activated semi cokes were measured. The experimental results showed that the activated semi coke has a high adsorption capacity for sulfur dioxide than the untreated semi coke. This may be the result of increase of surface area on activated semi coke and surface oxygen functional groups with basicity characteristics. Comparison to result of FTIR, it is known that group of —C—O—C? ?may be active center of SO 2 catalytic adsorption on activated semi coke.

Combustion characteristics of Daqing oil shale and oil shale semi-cokes

Thermo-gravimetric-analysis(TGA) was used to analyze the combustion characteristics of an oil shale and semi-cokes prepared from it.The effect of prior pyrolysis and TGA heating rate on the combustion process was studied.Prior pyrolysis affects the initial temperature of mass loss and the ignition temperature.The ignition temperature increases as the volatile content of the sample decreases.TG/DTG curves obtained at different heating rates show that heating rate has little effect on ignition temperature.But the peak of combustion shifts to higher temperatures as the heating rate is increased.The Coats-Redfern integration method was employed to find the combustion-reaction kinetic parameters for the burning of oil shale and oil shale semi-coke.

Effects of process parameters on pore structure of semi-coke prepared by solid heat carrier with dry distillation

The semi-coke was prepared by solid heat carrier with dry distillation in single factor method. The pore structures of raw coal and semi-coke were characterized by Brunauer-Emmett-Teller (BET) and scanning electron microscope (SEM). The results show that the adsorption and desorption isotherm of semi-coke are not coincident. There was a wide pore distribution on the semi-coke, in which mesopores and micropores account for a considerable proportion. Also there are many more secondary pores. With the increase of the final temperature of heat carrier and constant temperature, as well as the decrease of volume ratio of coal and hot carrier reactor, specific surface area and pore volume of semi-coke increased rapidly first and then decreased and finally increased, along with the rapidly reduction of average pore size. SEM photos show that the surface of semi-coke becomes increasingly rough and glossy.

Process optimization for treatment of methyltin mercaptide effluents using modified semi-coke

The central composite process optimization was performed by response surface methodology technique using a design for the treatment of methyltin mercaptide with modified semi-coke. The semi-coke from the coal industry was suitably modified by treating it with phosphoric acid, with a thermal activation process. The objective of the process optimization is to reduce the chemical oxygen demand （COD） and NH4＋-N in the methyltin mercaptide industrial effluent. The process variables considered for process optimization are the semi-coke dosage, adsorption time and effluent pH. The optimized process conditions are identified to be a semi-coke dosage of 80 g/L, adsorption time of 90 min and a pH value of 8.34. The ANOVA results indicate that the adsorbent dosage and pH are the significant parameters, while the adsorption time is insignificant, possibly owing to the large range of adsorption time chosen. The textural characteristics of modified semi-coke were analyzed using scanning electron microscopy and nitrogen adsorption isotherm. The average BET surface area of modified semi-coke is estimated to be 915 mE/g, with the average pore volume of 0.71 cm3/g and a average pore diameter of 3.09 nm, with micropore volume contributing to 52.36%.

Geological characteristics and exploration breakthroughs of coal rock gas in Carboniferous Benxi Formation,Ordos Basin,NW China

To explore the geological characteristics and exploration potential of the Carboniferous Benxi Formation coal rock gas in the Ordos Basin,this paper presents a systematic research on the coal rock distribution,coal rock reservoirs,coal rock quality,and coal rock gas features,resources and enrichment.Coal rock gas is a high-quality resource distinct from coalbed methane,and it has unique features in terms of burial depth,gas source,reservoir,gas content,and carbon isotopic composition.The Benxi Formation coal rocks cover an area of 16×104km^(2),with thicknesses ranging from 2 m to 25 m,primarily consisting of bright and semi-bright coals with primitive structures and low volatile and ash contents,indicating a good coal quality.The medium-to-high rank coal rocks have the total organic carbon(TOC)content ranging from 33.49%to 86.11%,averaging75.16%.They have a high degree of thermal evolution(Roof 1.2%-2.8%),and a high gas-generating capacity.They also have high stable carbon isotopic values(δ13C1of-37.6‰to-16‰;δ13C2of-21.7‰to-14.3‰).Deep coal rocks develop matrix pores such as gas bubble pores,organic pores,and inorganic mineral pores,which,together with cleats and fractures,form good reservoir spaces.The coal rock reservoirs exhibit the porosity of 0.54%-10.67%(averaging 5.42%)and the permeability of(0.001-14.600)×10^(-3)μm^(2)(averaging 2.32×10^(-3)μm^(2)).Vertically,there are five types of coal rock gas accumulation and dissipation combinations,among which the coal rock-mudstone gas accumulation combination and the coal rock-limestone gas accumulation combination are the most important,with good sealing conditions and high peak values of total hydrocarbon in gas logging.A model of coal rock gas accumulation has been constructed,which includes widespread distribution of medium-to-high rank coal rocks continually generating gas,matrix pores and cleats/fractures in coal rocks acting as large-scale reservoir spaces,tight cap rocks providing sealing,source-reservoir integration,and five types of efficient enrichment patterns(lateral pinchout complex,lenses,low-amplitude structures,nose-like structures,and lithologically self-sealing).According to the geological characteristics of coal rock gas,the Benxi Formation is divided into 8 plays,and the estimated coal rock gas resources with a buried depth of more than 2000 m are more than 12.33×10^(12)m^(3).The above understandings guide the deployment of risk exploration.Two wells drilled accordingly obtained an industrial gas flow,driving the further deployment of exploratory and appraisal wells.Substantial breakthroughs have been achieved,with the possible reserves over a trillion cubic meters and the proved reserves over a hundred billion cubic meters,which is of great significance for the reserves increase and efficient development of natural gas in China.

Numerical analysis on the factors affecting post-peak characteristics of coal under uniaxial compression

The post-peak characteristics of coal serve as a direct reflection of its failure process and are essential parameters for evaluating brittleness and bursting liability.Understanding the significant factors that influence post-peak characteristics can offer valuable insights for the prevention of coal bursts.In this study,the Synthetic Rock Mass method is employed to establish a numerical model,and the factors affecting coal post-peak characteristics are analyzed from four perspectives:coal matrix mechanical parameters,structural weak surface properties,height-to-width ratio,and loading rate.The research identifies four significant influencing factors:deformation modulus,density of discrete fracture networks,height-to-width ratio,and loading rate.The response and sensitivity of post-peak characteristics to single-factor and multi-factor interactions are assessed.The result suggested that feasible prevention and control measures for coal bursts can be formulated through four approaches:weakening the mechanical properties of coal pillars,increasing the number of structural weak surfaces in coal pillars,reducing the width of coal pillars,and optimizing mining and excavation speed.The efficacy of measures aimed at weakening the mechanical properties of coal is successfully demonstrated through a case study on coal burst prevention using large-diameter borehole drilling.

Disasters of gas-coal spontaneous combustion in goaf of steeply inclined extra-thick coal seams

In light of the escalating global energy imperatives,mining of challenging-to-access resources,such as steeply inclined extra-thick coal seams(SIEC),has emerged as one of the future trends within the domain of energy advancement.However,there is a risk of gas and coal spontaneous combustion coupling disasters(GCC)within the goaf of SIEC due to the complex goaf structure engendered by the unique mining methodologies of SIEC.To ensure that SIEC is mined safely and efficiently,this study conducts research on the GCC within the goaf of SIEC using field observation,theoretical analysis,and numerical modeling.The results demonstrate that the dip angle,the structural dimensions in terms of width-to-length ratio,and compressive strength of the overlying rock are the key factors contributing to the goaf instability of SIEC.The gangue was asymmetrically filled,primarily accumulating within the central and lower portions of the goaf,and the filling height increased proportionally with the advancing caving height,the expansion coefficient,and the thickness of the surrounding rock formation.The GCC occurs in the goaf of SIEC,with an air-return side range of 41 m and an air-intake side range of 14 m,at the intersection area of the“<”-shaped oxygen concentration distribution(coal spontaneous combustion)and the“>”-shaped gas concentration distribution(gas explosion).The optimal nitrogen flow rate is 1000 m3/h with an injection port situated 25 m away from the working face for the highest nitrogen diffusion efficacy and lowest risk of gas explosion,coal spontaneous combustion,and GCC.It has significant engineering applications for ensuring the safe mining of SIEC threatened by the GCC.

Stability analysis of longwall top-coal caving face in extra-thick coal seams based on an innovative numerical hydraulic support model

The relationship between support and surrounding rock is of great significance to the control of surrounding rock in mining process.In view of the fact that most of the existing numerical simulation methods construct virtual elements and stress servo control to approximately replace the hydraulic support problem,this paper establishes a new numerical model of hydraulic support with the same working characteristics as the actual hydraulic support by integrating numerical simulation software Rhino,Griddle and FLAC3D,which can realize the simulation of different working conditions.Based on this model,the influence mechanism of the supporting strength of hydraulic support on surrounding rock stress regulation and coal stability in front of the top coal caving face in extra thick coal seam were researched.Firstly,under different support intensity,the abutment pressure of the bearing coal and the coal in front of it presents the “three-stage”evolution characteristics.The influence range of support intensity is 15%–30%.Secondly,1.5 MPa is the upper limit of impact that the support strength can have on the front coal failure area.Thirdly,within a displacement range of 2.76 m from the coal wall,a support strength of1.5 MPa provides optimal control of the horizontal displacement of the coal.

Structural properties of residual carbon in coal gasification fine slag and their influence on flotation separation and resource utilization:A review

Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery and the high-value utilization of residual carbon(RC)in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits.The structural properties,such as pore,surface functional group,and microcrystalline structures,of RC in FS(FS-RC)not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC.In this paper,the characteristics of FS-RC in terms of pore structure,surface functional groups,and microcrystalline structure are sorted out in accordance with gasification type and FS particle size.The reasons for the formation of the special structural properties of FS-RC are analyzed,and their influence on the flotation separation and high-value utilization of FS-RC is summarized.Separation methods based on the pore structural characterist-ics of FS-RC,such as ultrasonic pretreatment-pore-blocking flotation and pore breaking-flocculation flotation,are proposed to be the key development technologies for improving FS-RC recovery in the future.The design of low-cost,low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future.The high-value utilization of FS should be based on the physicochemical structural proper-ties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to es-tablish an environmentally friendly utilization method.This review is of great theoretical importance for the comprehensive understand-ing of the unique structural properties of FS-RC,the breakthrough of the technological bottleneck in the efficient flotation separation of FS,and the expansion of the field of the high value-added utilization of FS-RC.

Thermally-induced cracking behaviors of coal reservoirs subjected to cryogenic liquid nitrogen shock

The benefits of using cryogenic liquid nitrogen shock to enhance coal permeability have been confirmed from experimental perspectives.In this paper,we develop a fully coupled thermo-elastic model in combination with the strain-based isotropic damage theory to uncover the cooling-dominated cracking behaviors through three typical cases,i.e.coal reservoirs containing a wellbore,a primary fracture,and a natural fracture network,respectively.The progressive cracking processes,from thermal fracture initiation,propagation or cessation,deflection,bifurcation to multi-fracture interactions,can be well captured by the numerical model.It is observed that two hierarchical levels of thermal fractures are formed,in which the number of shorter thermal fractures consistently exceeds that of the longer ones.The effects of coal properties related to thermal stress levels and thermal diffusivity on the fracture morphology are quantified by the fracture fractal dimension and the statistical fracture number.The induced fracture morphology is most sensitive to changes in the elastic modulus and thermal expansion coefficient,both of which dominate the complexity of the fracture networks.Coal reservoir candidates with preferred thermal-mechanical properties are also recommended for improving the stimulation effect.Further findings are that there exists a critical injection temperature and a critical in-situ stress difference,above which no thermal fractures would be formed.Preexisting natural fractures with higher density and preferred orientations are also essential for the formation of complex fracture networks.The obtained results can provide some theoretical support for cryogenic fracturing design in coal reservoirs.

Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents

The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction.Thus,a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents.Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions.In this study,the composition and content of liquefied solvents were analyzed.As model compounds,hexadecane,toluene,naphthalene,tetrahydronaphthalene,and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic,bicyclic,and tricyclic aromatic hydrocarbons.The solubility of hydrogen X(mol/mol)in pure solvent components and mixed solvents(alkanes and aromatics mixed in proportion to the chain alkanes+bicyclic aromatic hydrocarbons,bicyclic saturated aromatic hydrocarbons+bicyclic aromatic hydrocarbons,and bicyclic aromatic hydrocarbons+compounds containing het-eroatoms composed of mixed components)are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa.The results demonstrated that at high temperatures and pressures,the solubility of hydrogen in the solvent increases with the increase in temperature and pressure,with the pressure having a greater impact.Further-more,the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents,and the solubility of eicosanoids reaches a maximum of 0.296.The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number.The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons.The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents.Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms.

Pore-pressure and stress-coupled creep behavior in deep coal:Insights from real-time NMR analysis

Understanding the variations in microscopic pore-fracture structures(MPFS) during coal creep under pore pressure and stress coupling is crucial for coal mining and effective gas treatment. In this manuscript, a triaxial creep test on deep coal at various pore pressures using a test system that combines in-situ mechanical loading with real-time nuclear magnetic resonance(NMR) detection was conducted.Full-scale quantitative characterization, online real-time detection, and visualization of MPFS during coal creep influenced by pore pressure and stress coupling were performed using NMR and NMR imaging(NMRI) techniques. The results revealed that seepage pores and microfractures(SPM) undergo the most significant changes during coal creep, with creep failure gradually expanding from dense primary pore fractures. Pore pressure presence promotes MPFS development primarily by inhibiting SPM compression and encouraging adsorption pores(AP) to evolve into SPM. Coal enters the accelerated creep stage earlier at lower stress levels, resulting in more pronounced creep deformation. The connection between the micro and macro values was established, demonstrating that increased porosity at different pore pressures leads to a negative exponential decay of the viscosity coefficient. The Newton dashpot in the ideal viscoplastic body and the Burgers model was improved using NMR experimental results, and a creep model that considers pore pressure and stress coupling using variable-order fractional operators was developed. The model’s reasonableness was confirmed using creep experimental data. The damagestate adjustment factors ω and β were identified through a parameter sensitivity analysis to characterize the effect of pore pressure and stress coupling on the creep damage characteristics(size and degree of difficulty) of coal.

多功能CoAl-LDH/CdS光催化剂的制备及其性能研究

在能源危机和环境污染的双重挑战下,开发集能量转化和环境治理于一体的多功能光催化剂是促进太阳能-化学能转化的有效策略。采用正六边形的CoAl-LDH纳米薄片为载体,通过原位生长CdS纳米颗粒的方法,构建了CoAl-LDH/CdS的Ⅱ型异质结。利用CoAl-LDH纳米薄片在可见光区域的宽普吸收性和良好载体的特性,结合CdS的高光量子产率,再通过异质结构的构建,获得了多功能CoAl-LDH/CdS光催化材料。并通过优化CdS的负载量,获得的CoAl-LDH/CdS-2光催剂降解罗丹明B的降解率最大(在光催化降解时间t=60 min时内,降解率=88.48%),分别是CdS和CoAl-LDH单体的1.18倍和8.62倍。其中CoAl-LDH/CdS-1的CO产量最高为39.02 mol/g,分别是纯CoAl-LDH和纯CdS的4.2倍和2.5倍,这主要归功于复合材料中CoAl-LDH纳米片和CdS纳米颗粒间紧密异质结构的构建,丰富的耦合界面大大降低了光生载流子的复合率,这为多功能光催化剂的开发提供了理论基础。

Incorporating empirical knowledge into data-driven variable selection for quantitative analysis of coal ash content by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy(LIBS)has become a widely used atomic spectroscopic technique for rapid coal analysis.However,the vast amount of spectral information in LIBS contains signal uncertainty,which can affect its quantification performance.In this work,we propose a hybrid variable selection method to improve the performance of LIBS quantification.Important variables are first identified using Pearson's correlation coefficient,mutual information,least absolute shrinkage and selection operator(LASSO)and random forest,and then filtered and combined with empirical variables related to fingerprint elements of coal ash content.Subsequently,these variables are fed into a partial least squares regression(PLSR).Additionally,in some models,certain variables unrelated to ash content are removed manually to study the impact of variable deselection on model performance.The proposed hybrid strategy was tested on three LIBS datasets for quantitative analysis of coal ash content and compared with the corresponding data-driven baseline method.It is significantly better than the variable selection only method based on empirical knowledge and in most cases outperforms the baseline method.The results showed that on all three datasets the hybrid strategy for variable selection combining empirical knowledge and data-driven algorithms achieved the lowest root mean square error of prediction(RMSEP)values of 1.605,3.478 and 1.647,respectively,which were significantly lower than those obtained from multiple linear regression using only 12 empirical variables,which are 1.959,3.718 and 2.181,respectively.The LASSO-PLSR model with empirical support and 20 selected variables exhibited a significantly improved performance after variable deselection,with RMSEP values dropping from 1.635,3.962 and 1.647 to 1.483,3.086 and 1.567,respectively.Such results demonstrate that using empirical knowledge as a support for datadriven variable selection can be a viable approach to improve the accuracy and reliability of LIBS quantification.

Depositional Environment and Origin of Inertinite-rich Coal in the Ordos Basin

Inertinite-rich coal is widely distributed in the Ordos Basin,represented by the No.2 coal seam of the Middle Jurassic Yan'an Formation.This paper combined coal petrology and geochemistry to analyze the origin of inertinite,changes in the coal-forming environment and control characteristics of wildfire.Research has shown that there are two forms of inertinite sources in the study area.Alongside typical fusinization,wildfire events also play a substantial role in inertinite formation.There are significant fluctuations in the coal-forming environment of samples at different depths.Coal samples were formed in dry forest swamp with low water levels and strong oxidation,which have a high inertinite content,and the samples formed in wet forest swamp and limnic showed low inertinite content.Conversely,the inertinite content of different origins does not fully correspond to the depositional environment characterized by dryness and oxidation.Nonpyrogenic inertinites were significantly influenced by climatic conditions,while pyrofusinite was not entirely controlled by climatic conditions but rather directly impacted by wildfire events.The high oxygen level was the main factor causing widespread wildfire events.Overall,the combination of wildfire activity and oxidation generates a high content of inertinite in the Middle Jurassic coal of the Ordos Basin.

Geochemical and petrological studies of high sulfur coal and overburden from Makum coalfield (Northeast India) towards understanding and mitigation of acid mine drainage

Opencast coal mining produces trash of soil and rock containing various minerals,that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drainage(AMD)through oxidation pyrite minerals.The current study entailed assessing the potential production of AMD from an opencast coal mining region in Northeast part of India.In order to have a comprehensive overview of the AMD problem in Makum coalfield,the physico-chemical,geochemical,and petrological characteristics of the coal and overburden(OB)samples collected from the Makum coalfield(Northeast India)were thoroughly investigated.The maceral compositions reveal that coal features all three groups of macerals(liptinite,vitrinite,and inertinite),with a high concentration of liptinite indicating the coal of perhydrous,thereby rendering it more reactive.Pyrite(FeS_(2))oxidation kinetics were studied by conducting the aqueous leaching experiments of coal and(OB)samples to interpret the chemical weathering under controlled laboratory conditions of various temperature and time periods,and to replicate the actual mine site leaching.Inductively coupled plasma-optical emission spectroscopy(ICP-OES)was operated to detect the disposal of some precarious elements from coal and OB samples to the leachates during our controlled leaching experiment.The Rare earth element(REE)enrichment in the samples shows the anthropogenic incorporation of the REE in the coal and OB.These experiments reveal the change in conductivity,acid producing tendency,total dissolved solid(TDS),total Iron(Fe)and dissolved Sulfate(SO_(4)^(2−))ions on progress of the leaching experiments.Moreover,the discharge of FeS_(2) via atmospheric oxidation in laboratory condition undergoes a significant growth with the rise of temperature of the reaction systems in the environment and follows pseudo first order kinetics.A bio-remediative strategies is also reported in this paper to mitigate AMD water by employing size-segregated powdered limestone and water hyacinth plant in an indigenously developed site-specific prototype station.Apart from neutralisation of AMD water,this eco-friendly AMD remediation strategy demonstrates a reduction in PHEs concentrations in the treated AMD water.