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To date, there has been little research on the history of work-related mental health issues among coal workers. Much of the coal extraction industry peaked during the early twentieth century and then began its precipitous decline. Mining has high casualty rates, and the medical field did not understand the long-term effects of psychological trauma on mine workers until recently. Newspaper articles and other historical records provide accounts of accidents and tragedies. Heroism is often emphasized in recalling tragic episodes at the expense of recording the emotional stress suffered by survivors. A diverse set of historical sources provides a context for work-related mental health issues in the coal extraction industry. Probing a set of historic oral histories of coal workers and creating analogies to current studies provide additional clues about the under-told story of these historic actors’ general health and well-being. While incorporating oral histories from other regions, focusing on the anthracite coal industry in northeastern Pennsylvania allows us to identify historical actors and helps us think differently about other working-class communities impacted by industrial capitalism. [ABSTRACT FROM AUTHOR]

The molten‐salt synthesis and electrochemical capacitive behaviors of porous carbon are reported using anthracite as the precursor. Upon synthesis, the binary KCl/K2CO3 molten salt not only exfoliates bulky anthracite to carbon nanosheets but also creates rich micro‐ and mesopores in the structure. The resulting porous carbon shows a large surface area of 1399.7 m2 g−1 and a total pore volume of 1.50 cm3 g−1. In 6.0 mol L−1 KOH aqueous electrolyte, it delivers a high specific capacitance of 245.6 F g−1 at a current density of 0.5 A g−1. Flexible micro‐supercapacitors with this porous carbon are assembled following an interdigitated design. The micro‐supercapacitor affords an area capacitance of 18.0 mF cm−2 and an energy density of 1.58 µWh cm−2 at a power density of 20 µW cm−2, and sustains 89.6% of the capacitance after 2000 cycles. Furthermore, the strain sensor fabricated by replacing the current‐collecting fluid at both ends of the electrode provides consistent and stable signal output, regardless of the degree of bending and the number of cycles. This study demonstrates the great potential of anthracite‐based porous carbon in flexible energy and electronic microdevices. [ABSTRACT FROM AUTHOR]

The conventional modes of transporting coal frequently result in substantial fiscal challenges and environmental deterioration. Slurry-based hydraulic transportation of coal through pipelines has proven to be a feasible and efficient method, offering economic benefits, reliability and minimal ecological damage. Due to the limited and rapidly depleting reserves of high-rank coal, the scientific community is compelled to utilize high ash coal (HAC) to meet the growing demands of the population. The HAC slurry is characterized by poor slurryability, stability and low calorific value. This research presents a straightforward solution to enhance the slurryability and stability of Indian HAC while improving its calorific value. Anthracite and anionic additive sodium dodecyl sulfate (SDS) were added in Indian HAC to prepare a high solid loading blended slurry with improved stability. The rheological characteristics, stability and zeta potential of prepared slurry samples were assessed and analyzed to determine the optimum anthracite proportion and SDS concentration. The optimum anthracite proportion and SDS concentration for low apparent viscosity and maximum stability were 30% and 0.6%, respectively. The inclusion of anthracite and SDS at optimal proportion yielded a slurry with 66% solid concentration, indicating a surge of 14% in the maximum possible solid loading. [ABSTRACT FROM AUTHOR]

In order to investigate the influence mechanism of temperature on the permeability of loose coal body in the process of spontaneous combustion of residual coal in the gob, the mathematical model of the permeability of coal body under different temperature conditions was established by considering the effects of temperature-induced adsorption deformation, thermal expansion deformation, thermal fission deformation and sliding effect, etc., and the parameters of the single influencing factors of the mathematical model of the permeability were controlled by the method of controlling variables to investigate the influence mechanism of the temperature change on the permeability of the loose coal body. Based on the principle of physical similarity, an experimental platform for loose coal seepage was designed and constructed, and anthracite coal from Chengzhuang Mine in Shanxi Province was selected as the experimental object, and air was used as the seepage gas to simulate the underground environment, so that gas transport experiments were carried out in the loose coal body under different temperature conditions (40-100 ℃), different injection pressures (0.3-0.5 MPa), and different permeability pressures (0.04-0.08 kPa). The mechanism of the influence of temperature change on the permeability of the loose coal body was investigated by mutual verification of the experimental and modeling results. The results show that: the permeability of loose coal body increases exponentially with the increase of gas pressure gradient; under the condition of the same pressure gradient, the permeability decreases gradually with the increase of temperature; the influence of the temperature on the permeability is small when it is from 40 ℃ to 60 ℃, and the change of the permeability is not obvious, and the permeability starts to decrease after 60 ℃, and the decrease of the permeability is more significant when it is from 90 ℃ to 100 ℃; under the influence of the slippage effect, the increase of the injection pressure inhibits the permeability of the coal body. Under different osmotic pressure conditions (0.04-0.08 kPa), the model values of the permeability of the loose coal body and the experimental values of the seepage flow are in high agreement. With the increase of temperature, adsorption deformation has an inhibitory effect on the permeability of the loose coal body, thermal cracking deformation and the slipping effect have a promotional effect on the permeability of the loose coal body, and the effect of the deformation of the thermal expansion on the permeability of the loose coal body is weak. Temperature affects the permeability of loose coal body through the combined effect of adsorption deformation, thermal cracking deformation and sliding effect.

In order to study the oxidation characteristics of anthracite at ambient temperature. Anthracite coal samples of three particle sizes were chosen for oxidation in a closed space at 25°C, thus the characteristics of O2 consumption and CO production during ambient temperature oxidation of anthracite were obtained for different particle sizes. The results showed that the O2 consumption rate and CO production rate of anthracite during the ambient temperature oxidation process were large at the beginning and then gradually decrease and finally reach equilibrium. The O2 consumption rate increases with increasing particle size in the range of 0.05–1.00 mm. In contrast, the rate of CO production exhibited a nonlinear pattern, which was highest for the medium-sized coal samples and lower for the largest and smallest samples. The ambient temperature oxidation experiment was repeated on the oxidized coal samples after rinsing with fresh air, during which CO can still be produced and the time needed for the reaction to reach equilibrium was shortened. In addition, the consumption of O2 and the production of CO were much lower than those of the first oxidation, and the influence of particle size on both the rates of oxygen consumption and CO production exhibited a nonlinear correlation. Comparing the results of the two experiments, the oxidation rate was fastest for coal samples with a particle size of 0.10–0.50 mm, while the oxidation rate of coal decreased when the particle size of coal samples was less than 0.10 mm. The research has some reference significance for fire prevention in anthracite coal mines. [ABSTRACT FROM AUTHOR]

In order to determine the influence of anisotropy induced by primary bedding structure on fracture toughness and fracture process zone (FPZ) incubation characteristics of anthracite, the notched semi-circular bending (NSCB) anthracite samples with different bedding angles were subjected to the mode I three-point bending loading test on the MTS hydraulic servo test system. The incubation process of FPZ at crack tip was monitored by the digital image correlation method (DICM) combined with the acoustic emission (AE) localization technique. Based on the Irwin-Bazant model, the Strip-yield uniform traction model and the Strip-yield linear traction model, the fully developed FPZ length of anthracite samples were predicted and compared with the experimental results. The geometric morphology of anisotropic anthracite FPZ and the shear and tensile deformation time series of anthracite FPZ during its incubation at different bedding angles were discussed. The results show that the peak load, peak displacement and fracture toughness of anthracite increase with the increase of bedding inclination. Compared with the coal samples with the bedding angle of 0°, the average fracture toughness of the coal samples with the bedding angle of 22.5°, 45.0°, 67.5° and 90.0° increases by 6.76%, 86.82%, 85.47% and 134.46%, respectively. The FPZ length predicted by the Irwin-Bazant model and the Strip-yield uniform traction model is shorter than the test value, while the prediction of the Strip-yield linear traction model is generally higher than the test value. The estimation of FPZ length of anthracite by the Strip-yield uniform traction model is most close to the experimental value, indicating that the distribution of the cohesive force at the crack tip of the anthracite sample tends to be more uniform. The FPZ length of anthracite sample is proportional to the square of the ratio of fracture toughness and tensile strength: L∝(KIC/σt)2. The prefabricated crack tip deformation of the sample is dominated by tensile deformation and assisted by shear. The tensile deformation ranges from 27.71% to 57.26% Pmax, and the shear deformation ranges from 72.88% to 92.4% Pmax. The time of tensile deformation of the crack tip is superior to that of shear deformation. The strain field distribution on the circumferential measuring lines of the samples with the bedding angle of 0° and 45° is similar to the texture distribution of onion cross section, while the maximum principal strain monitoring value of the samples with the bedding angle of 90° shows a fluctuation and disordered distribution at most measuring angles. The strain gradient of anthracite sample is different on the divergence line of FPZ tip in each direction.

The change of water occurrence form and content in coal will change the physical characteristics and pore structure of coal, and then affect its crushing process.In order to study the effect of moisture contained in coal on on the crushing behavior of coal particles,anthracite coal was used as the research object. A Hastelloy grinding equipped with a power measuring device was applied to simulate the crushing environment in a medium-speed coal mill. The individual and mixed crushing experiments were carried out in multi-time batches of coal samples with different water content. Thus, the effects of water occurrence on coal crushing rate, pulverized coal fineness, and grinding energy consumption were studied. The experimental results showed that compared with the original coal samples, the initial particle size material crushing rate of homogenized soaked coal samples decreases significantly due to the increase of water content, its grindability index first decreased and then increased with increasing the water content when the homogenized immersed coal sample was crushed separately, and the fineness of pulverized coal t10 was positively correlated with water content. When dry and wet coal samples were mixed and crushed, the crushing rate and fine-grained material generation rate of 13.34% moisture content samples were much higher than that of homogenized soaked coal samples with the same moisture content, and their its grindability index was larger than that of the original coal; The grindability index of the blended coal samples with other moisture contents was slightly smaller than that of the homogenized soaked coal samples, and this difference became larger with the increase of moisture content, while the crushing rate and the yield of fine-grained materials differed less from that of the homogenized impregnated coal samples. Also, the result indicated that the classical energy-particle size relationship model may be used to characterize the individual and mixed crushing processes of samples with different moisture gradients. The internal and external moisture reduced the ability of anthracite to resist crushing to varying degrees, and increasing the water content during separate crushing improved the energy efficiency significantly. So, the water content parameters were introduced into the energy consumption model to characterize the crushing process of various moisture coal samples. By exploring the influence mechanism of water content in coal on energy consumption of coal crushing, it reveals the way of energy loss in the process of coal crushing and provides theoretical guidance for optimizing coal crushing process and reducing energy consumption.

Commercial graphite anodes face the problems of high preparation temperature and limited specific capacity in lithium‐ion batteries (LIBs). Amorphous carbon anode materials are prepared at low temperatures and have abundant sources and modes of preparation. As a low‐cost carbon source material, anthracite has a practical application value in storing lithium as anode electrodes of LIBs. However, the capacity is not enough to meet the present increasing demand. We added CNTs to enhance the performance of anthracite‐based carbon anodes. The addition of CNTs significantly improves the electrical properties of amorphous carbon anode materials due to their good electronic conductivity. This anthracite‐based carbon with CNTs (A−C) anode displays a specific cycling capacity of 360 mAh ⋅ g−1 at the current density of 200 mA ⋅ g−1 after 200 cycles in LIBs. We believe that the work has far‐reaching significance for improving the practicability of amorphous carbon anode materials. [ABSTRACT FROM AUTHOR]

The possibility of producing carbon–carbon composites by catalytic chemical vapor deposition has been investigated. Anthracite dust of deposits in the Gorlovskii basin was used as an initial carbon matrix. Salts of nickel acetate and iron oxalate were used to form catalytically active metal particles (nickel and iron) on the surface of anthracite. The precursor salts were supported by an incipient wetness impregnation of anthracite samples with aqueous solutions. Optimal conditions of thermal treatment in inert and reducing media were determined for the used salts. Scanning electron microscopy was used to study the secondary structures of the original anthracite with supported metals and synthesized carbon–carbon composites. Using the low-temperature nitrogen adsorption method, a significant increase in the specific surface area of an anthracite sample with supported nickel as a result of its treatment in an atmosphere of saturated C2–C4 hydrocarbons at 600°C was demonstrated. [ABSTRACT FROM AUTHOR]

Hydraulic transportation of lignite and high ash coal (HAC) is economically unviable due to their poor slurryability and stability. The study suggests and shows how the proper selection of appropriate size range and proportion of anthracite for blending can aid in the economical preparation of highly concentrated HAC slurry. Fine (+0–53 µm), coarse (+53–106 µm), and coarser (+106–150 µm) anthracite particles were added to the HAC sample. The proportion of anthracite particles was varied in the range of 10–40% (by weight), to obtain 12 blended tetra-modal samples. To determine the optimum size range and proportion of anthracite, the stability and rheological characteristics of both tri-modal HAC and blended tetra-modal coal samples were assessed. The addition of a fine anthracite sample (+0–53 µm) has an adverse impact on the rheological characteristics. The optimum size range and proportion of anthracite particles for enhanced slurryability and low apparent viscosity are found to be +106–150 µm and 30%, respectively. Optimal blending yields a 68% maximum solid concentration slurry. By taking advantage of both the tetra-modal particle size distribution and anthracite's high slurryability characteristics, the maximum achievable solid concentration of HAC slurry increases by 17%. [ABSTRACT FROM AUTHOR]

Context: To investigate the influence of different concentrations of surfactants on the adsorption of anthracite, the nonionic surfactant alkyl polyglucoside (APG) was selected. The study examined the adsorption characteristics of different concentrations of APG on the surface of anthracite. The results revealed the existence of two modes of APG adsorption on anthracite. Under the action of 0.06 wt% APG, APG was found to adsorb in a monolayer state on the anthracite surface, with a saturation adsorption capacity of 20.06 mg/g. When the solution concentration exceeded 0.14 wt%, APG exhibited a double-layer saturation adsorption state on anthracite, with a saturation adsorption capacity of 71.71 mg/g. Molecular dynamics simulations complemented these findings, demonstrating that low concentrations of APG could reduce the mobility of water molecules and enhance the hydrophilicity of anthracite. With an increase in the number of APG molecules, multi-layer adsorption occurred on the anthracite surface, making it more hydrophobic. Therefore, the differences in wettability of anthracite induced by different concentrations of APG were primarily attributed to the spatial distribution of the surfactant at the water/coal interface. Methods: This study analyzed the adsorption capacity of the surfactant through adsorption experiments and Fourier-transform infrared spectroscopy (FTIR) experiments. Molecular dynamics simulations were conducted to construct six concentration levels of water/APG/anthracite systems. Various aspects, including APG adsorption configurations, interaction energies, relative concentrations of each component, and the diffusion coefficient of water molecules, were discussed to elucidate the reasons for the differential wettability of anthracite induced by different concentrations of APG. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

CO2-enhanced coalbed methane recovery (CO2-ECBM) has been demonstrated as an effective enhanced oil recovery (EOR) technique that enhances the production of coalbed methane (CBM) while achieving the goal of CO2 sequestration. In this paper, the grand canonical Monte Carlo simulation is used to investigate the dynamic mechanism of CO2-ECBM in anthracite pores. First, an anthracite pore containing both organic and inorganic matter was constructed, and the adsorption and diffusion characteristics of CO2 and CH4 in the coal pores under different temperature and pressure conditions were studied by molecular dynamics (MD) simulations. The results indicate that the interaction energy of coal molecules with CO2 and CH4 is positively associated with pressure but negatively associated with temperature. At 307.15 K and 101.35 kPa, the interaction energies of coal adsorption of single-component CO2 and CH4 are −1273.92 kJ·mol−1 and −761.53 kJ·mol−1, respectively. The interaction energy between anthracite molecules and CO2 is significantly higher compared to CH4, indicating that coal has a greater adsorption capacity for CO2 than for CH4. Furthermore, the distribution characteristics of gas in the pores before and after injection indicate that CO2 mainly adsorbs and displaces CH4 by occupying adsorption sites. Under identical conditions, the diffusion coefficient of CH4 surpasses that of CO2. Additionally, the growth rate of the CH4 diffusion coefficient as the temperature increases is higher than that of CO2, which indicates that CO2-ECBM is applicable to high-temperature coal seams. The presence of oxygen functional groups in anthracite molecules greatly influences the distribution of gas molecules within the pores of coal. The hydroxyl group significantly influences the adsorption of both CH4 and CO2, while the ether group has a propensity to impact CH4 adsorption, and the carbonyl group is inclined to influence CO2 adsorption. The research findings are expected to provide technical support for the effective promotion of CO2-ECBM technology. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gas injection for enhancing gas recovery (GI–EGR) is a multifaceted process that requires a solid theoretical foundation to be implemented orderly. However, there are limited reports on the micro-mechanisms of GI–EGR technology applied to coalbed methane reservoirs, especially for deep strata. To address this gap, this study utilized molecular simulation techniques to construct the organic pore models of anthracite with varying sizes and morphologies, and explored the micro-dynamic behaviors of CH4 and various gas injected components including N2, CO2 and flue gas confined in nanopores. The aim was to reveal the competitive adsorption mechanisms of gases in multi-component systems under shallow and deep geological conditions. The results demonstrated that the isosteric heats of CH4, N2 and CO2 all increased after the transition from shallow to deep, with rising amplitudes of 18.8%, 22.8% and 17.8%, respectively, in the respective single-component systems. In multi-component adsorption models, the isosteric heats remained higher than those under shallow conditions, but there were some small fluctuations due to the interference between various gases. On the other hand, the self-diffusion coefficients of single CH4, N2 and CO2 in the deep condition decreased by 37.6%, 27.2% and 23.1%, respectively, compared to those in conventional shallow conditions. As a consequence, the difference in diffusivity among various gases would get narrowed. The molecular-level observations herein have the potential to improve the understanding of gas occurrence and lay a solid foundation for the GI–EGR technology. [ABSTRACT FROM AUTHOR]

The anthracite coal mining landscape of northeastern Pennsylvania is in ruin, a by-product of two centuries of unchecked capitalism. Much of the land is stripped of its timber and surface mines lay abandoned. The industry began its decline after WWI and virtually collapsed during the post-WWII era. Waste piles of coal litter the landscape, and the streams and rivers are considered dead because of the minerals and high acid content of water draining from abandoned mines. Many scholars have written about the extreme work conditions the coal workers faced, the demise of the coal industry, and the impact of deindustrialization on the region's people. Often overlooked is how members of the mining communities had a radical hope. Radical hope helps oppressed people to see that another condition and another world is possible, although not guaranteed. Re-examining oral histories from the anthracite region recorded in the 1970s, when the industry was in its great decline, demonstrates how these mining communities anticipated a future good, understanding the struggle to attain it. [ABSTRACT FROM AUTHOR]

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized via a facile one-pot solvothermal process using coal (Jin 15 Anthracite and Shaerhu lignite) as raw materials and dimethyl formamide (DMF) as the solvent, employing a microwave pyrolysis method. This approach demonstrates remarkable efficacy in the development of nitrogen-doped carbon dots (N-CDs) with a high quantum yield (QY). The N-CDs prepared have strong photoluminescence properties. Moreover, the obtained N-CDs emit blue PL and are easily dispersed in polymethyl methacrylate (PMMA), preserving the inherent advantages of N-CDs and the PMMA matrix. The JN-CDs exhibit a high quantum yield (QY) of 49.5% and a production yield of 25.7%, respectively. In contrast, the SN-CDs demonstrate a quantum yield of 40% and a production yield of 35.1%. It is worth noting that the production yield and quantum yield of coal-based carbon dots are inversely related indices. The lower metamorphic degree of subbituminous coal favors an enhanced product yield, while the higher metamorphic degree of anthracite promotes an improved quantum yield in the product, which may be attributed to the presence of amorphous carbon within it. Consequently, we propose and discuss potential mechanisms underlying N-CD formation. [ABSTRACT FROM AUTHOR]

This article summarises the possibility of replacing the coke breeze sintering fuel with an economically and ecologically more suitable fuel, anthracite. The main focus is on the possibility of replacing coke breeze with anthracite, during which, the replacement process is accelerated and the other properties are also affected. The analyses performed showed that the replacement of coke breeze with different amounts of anthracite does not have a negative effect if the initial permeability of the sintering bed is the same. [ABSTRACT FROM AUTHOR]

Purpose. Development of a mathematical model for predicting critical deviations of furnace processes during the operation of anthracite boilers converted to burning sub-bituminous coal, including in non-design modes of operation. Verification of the calculation model of the TPP-210A boiler of the 300 MW power unit on the design fuel – anthracite for further analysis of its operation on sub-bituminous coal. Methodology. Modelling of solid fuel combustion was performed with the help of finite-element CFD models of the boiler unit in the ANSYS-Fluent software complex with the determination of the relevant characteristics of the boiler. Findings. Finite-element CFD models were developed according to the working drawings of the TPP-210A boiler and its burner device, reconstructed for burning sub-bituminous coal. Verification of the results of CFD modeling was carried out for the case of burning the design fuel – anthracite in the design operating modes. It is shown that the discrepancy between the results and the experiment does not exceed 6.5 %, which allows the use of the developed computer model for simulating the burning of subbituminous coal, including in non-design operating modes. The obtained results are the basis for further calculations of the operation of the TPP-210A boiler of the 300 MW power unit on sub-bituminous coal with the determination and minimization of the factors of critical deviations of furnace processes that lead to thermal damage of wall screens. Originality. For the first time, CFD modelling has taken into account all the design features of the burner devices of the TPP210A boiler, reconstructed for burning sub-bituminous coal with the introduction of a steam ejector of a high-concentration dust pipe under rarefaction to the central air channel. For the first time, the distribution of thermal resistances has been applied as boundary conditions on the walls of the fuel tank for the case of burning sub-bituminous coal. The validity of these approaches was confirmed by the verification of the results. Practical value. The verified computer model of the TPP-210A boiler of the 300 MW power unit converted to burning sub-bituminous coal will allow determining and minimizing the factors of critical deviations of furnace processes which lead to thermal damage of wall screens. This will contribute to increasing the reliability and improving the technical and economic indicators of the boilers of the Trypilska TPP, where 3 such boilers are operating, and other power plants (Zmiyivska, Kryvorizka, Prydniprovska), where similar anthracite boilers are planned to be converted to sub-bituminous coal. [ABSTRACT FROM AUTHOR]

Magnetite ore pellets oxidize to hematite during their induration in a mild oxidizing atmosphere of strand which produces internal heat in the pellet and enhances diffusion bonding. Hematite ore pellet does not have such oxidation. Therefore, hematite pellets require a much higher induration temperature (>1300°C). To reduce the induration temperature requirement (maximum temperature of the strand) of hematite pellets, investigators have added several additives, namely, coke fines, coal fines, charcoal, anthracite, Jhama coal, blast furnace flue dust, etc. as carbon sources. Carbon in these materials oxidizes in the mild oxidizing atmosphere of the strand and provides in-situ exothermic heat which helps in the bonding of pellets. Investigators have also added lower iron oxides containing materials for this purpose, namely, magnetite ore, mill scale, and sludge which oxidize and provide diffusion bonding and exothermic heat. However, each of the above materials has a different character of reaction based on its chemistry, particle size and shapes, surface morphology, distribution, and concentration. Therefore, they affect differently on the pellet properties. Several studies reported so far on the effects of each material, their optimum requirement, advantages, and disadvantages are discussed along with their comparative analysis. This will help identify the appropriate additive and their amount of requirement in hematite pellets. [ABSTRACT FROM AUTHOR]

The effect of metal nitrates on the activation of anthracite combustion process has been studied. Fe(NO3)2 · 9H2O and Cu(NO3)2 · 3H2O were used as nitrates in an amount of 5 wt% applied to anthracite powder (fraction less than 0.1 mm) by incipient wetness impregnation. Using scanning electron microscopy and EDX mapping, it was found that using this method of applying the additive makes it possible to achieve high dispersion and uniform distribution in the fuel composition. The characteristics of oxidation, ignition, and combustion were studied using thermal analysis methods and high-speed video recording in the combustion chamber at a temperature of 800°C. It was found that the use of metal nitrates contributes to an increase in the reactivity of anthracite as evidenced by a decrease in the temperature of the intensive oxidation beginning (ΔTi) by 23–84°C and the ignition delay time (Δti) by 0.9–2.2 seconds. The greatest effect of changing the reactivity of anthracite was recorded in the case of using copper nitrate additive. The use of nitrates also contributed to the decrease in the resulting fuel underburning (from 3.5 to 0.4 wt%) and gas-phase CO compounds (by 31–53%). At the early stages, combustion process of modified samples was accompanied by periodic formation of micro-explosions, which led to the activation and development of the particle surface. [ABSTRACT FROM AUTHOR]

The mixtures of graphite and anthracite with lithium carbonate in atmospheres of argon and air were studied using differential scanning calorimetry (DSC). It was found that, in a temperature range of 100–500°C, the weight loss in argon was stronger than that in air. This phenomenon was caused by the removal of oxygen compounds with carbon. Competing processes of the formation of oxygen compounds with carbon and coal and the desorption of oxygen-containing substances occurred in air. The thermal effects for graphite–lithium carbonate systems in argon and in air were compared using DSC and gravimetry curves. It was found that the molar ratio between carbon(IV) and carbon(II) oxides in the reaction products up to 700°C can be estimated at 10 : 1. Endothermic effects of lithium carbonate melting in an argon atmosphere for the mixtures of graphite and anthracite with lithium carbonate were observed at 732 and 727°C, respectively. The peaks of endothermic effects in air did not correspond to the heat absorption curves in argon. The most probable explanations of the observed effects were given: the presence of lithium carbonate and lithium oxide phases and the manifestation of the stretched nature of the pre-transition region of lithium carbonate. Using powder X-ray diffractometry, it was found that the burnout of a carbon phase at 500°C in graphite and anthracite did not lead to a significant change in the interplanar distances in lithium carbonate. [ABSTRACT FROM AUTHOR]

In this paper, anthracite in Shanxi region is taken as a research object, and the pore structure of coal under different freeze-thaw times is characterized and analyzed by scanning electron microscope and nitrogen adsorption experiment. The SEM experimental results show that the micron-scale cracks on the surface of anthracite gradually connect after freeze-thaw, and the secondary crack channels are formed around the pores and air holes, so that the pores also begin to connect. Further, the quantitative information of the picture was extracted, and it was found that the surface porosity and fractal dimension of the coal sample changed significantly after three freeze-thaw cycles, which increased by 163.3% and 15.9% respectively, and increased with the increase of freeze-thaw cycles. The results of low-temperature nitrogen adsorption experiments show that the coal samples after freeze-thaw are mainly crack, and the pore structure changes from simple to complex. In addition, the maximum nitrogen adsorption capacity, specific surface area and pore volume increased by 125.7%, 69.3% and 72.6%, respectively. With the increase of freeze-thaw times, the growth rates of maximum nitrogen adsorption capacity, specific surface area and pore volume are significantly different. The results of joint characterization show that the number of pores and cracks increases to different degrees after freezing and thawing. Comparing the increase in the degree of fracturing (163.3%) with the increase in the total pore volume (30.68%), we find that the degree of change of the crack after thawing is higher than that of the pore. In this paper, the damage effect of coal samples after freezing and thawing with liquid nitrogen is investigated from an experimental point of view, which accelerates the great leap of cyclic cryogenic fracturing technology from basic theory to technical practice. [ABSTRACT FROM AUTHOR]

While catalytic pyrolysis with catalyst addition has been widely studied with a primary focus on optimising gas, tar and char yields, studies exploring the evolution of char structure during coal pyrolysis remain scarce. This knowledge gap potentially affects subsequent char gasification processes during coal conversion within gasifiers. This study presents demineralised anthracite (TM) prepared by HCl–HF acid washing. The pyrolysis performance of TM while adding Ca, Fe and Ca–Fe composite catalysts was investigated through thermogravimetric analysis. The char structure, morphology and functional groups in the obtained char samples were clarified through X‐ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. The results indicated that de‐ashing by acid washing promoted the formation of C–O functional groups in coal due to the decomposition of C=O or a combination of oxygen with unsaturated carbon, or both. The TM sample exhibited improved thermal decomposition upon adding either Ca or Fe catalysts, which became more pronounced after adding the Ca–Fe composite catalyst under the same conditions. While the addition of Ca–Fe composite catalysts inhibited the crystalline carbon formation and char graphitisation degree compared to their individual additions, it led to enhanced decomposition of phenol C–O, thereby facilitating the thermal decomposition of TM. [ABSTRACT FROM AUTHOR]

Purpose. Development of scientific foundations and generalization of experience in development and implementation of technical solutions for conversion of CHPP anthracite boilers with steam productivity up to 250 t/h for combusting sub-bituminous coal with maximum use of existing equipment. Methodology. Consumption and heat calculations of pulverizing systems, aerodynamic calculations of pulverized coal pipes and burners, thermal calculations of boilers and combustion chambers. Calculation justification of technical solutions to eliminate the risk of coal ignition in pulverizing systems and in the burners. Industrial tests on CHPP boiler units. Findings. Different types of pulverizing systems of anthracite CHPP boilers with ball-drum mills, an intermediate pulverized coal hopper and with hot air as a drying agent were considered, and a classification of pulverizing systems by the method of pulverized coal transport to the burners (with drying agent or hot air), and boilers – by the type and location of the burners and the geometry of the furnace, was performed. The problems were analyzed, the calculations of pulverizing systems, pipes, burners, and boilers were performed according to the applied technical solutions, and the experience was summarized of conversion from anthracite to sub-bituminous coal in the boilers of Myronivska, Darnytska CHPP and of the first line of Slovianska TPP. Recommendations are given on methods of conversion of anthracite boilers with a steam capacity of up to 250 t/h with different types of pulverizing systems for burning sub-bituminous coal with maximum use of existing equipment. Originality. For pulverizing systems with ball-drum mills and an intermediate hopper for pulverized coal with hot air as a drying agent classification was made for the first time by the type of transporting agent, and it was shown that when converting from anthracite to sub-bituminous coal with the air transport of pulverized coal to the burners, it is necessary to use the selection of slightly heated air from the first stage of the air heater. It is substantiated that maintaining the temperature conditions of molten slag removal while reducing the share of hot air consumption to the furnace requires the preferential operation of pulverizing systems in a single-mill mode, which is possible due to the greater grindability of sub-bituminous coal. Practical value. Based on the experience of approving technical solutions at Myronivska, Darnytska CHPPs, and at the first line of Slovianska TPP, recommendations are given on how to transfer anthracite boilers with a steam capacity of up to 250 t/h with different types of pulverizing systems for burning sub-bituminous coal with maximum use of existing equipment. [ABSTRACT FROM AUTHOR]

Microwave energy and in situ stress cooperatively influence the permeability of coal reservoirs in microwave-assisted coalbed methane (CBM) extraction. In this study, the combined influence of microwave energy and load on the failure characteristics of coal reservoirs was investigated using acoustic emission (AE) technology. The failure characteristics of anthracite derived from microwave irradiation during uniaxial compression was analyzed from aspects such as the correlation dimension (D) of the AE time series, b-value, and AF–RA correlation. Then the combined mechanism of microwave energy and in situ stress was explored. The results indicated that microwave energy significantly affected the AE activity of anthracite under loading. Moreover, microwave irradiation lessened the damage intensity and increased the crush degree during loading. After low-energy microwave (≤ 90 kJ) irradiation, the AE signals of anthracite were active only in the unstable crack growth stage, with less damage under load, and mainly characterized by the rapid expansion of large fractures. In contrast, after high-energy microwave (> 90 kJ) irradiation, AE signals penetrate the entire loading process, and the required energy for damage decreased, mostly manifested as small-scale microcracks. Additionally, microwave irradiation changed the failure mode of anthracite under loading from shear failure to tensile failure. In summary, microwave thermal effect reduced the stress threshold for fracture propagation by improving the physical structure of coal reservoirs. Cracks initiated by microwave irradiation could cause in situ stress redistribution, forming stress reduction areas and stress concentration areas, thereby accelerating the expansion of fracture networks. Therefore, the results of this study have great significance for optimizing the scheme of microwave-assisted CBM extraction and improving the CBM production rate through effective utilization of in situ stress. Highlights: Microwave irradiation enhances the AE activity of anthracite under load. Microwave irradiation decreases the failure intensity and increases the damage degree of anthracite. Microwave irradiation changes the failure mode of anthracite from shear failure to tensile failure. The cooperative mechanism of microwave energy and in situ stress during microwave-assisted CBM extraction is discussed. [ABSTRACT FROM AUTHOR]

Hard carbon is regarded as one of the greatest potential anode materials for sodium-ion batteries (SIBs) because of its affordable price and large layer spacing. However, its poor initial coulombic efficiency (ICE) and low specific capacity severely restrict its practical commercialization in SIBs. In this work, we successfully constructed abundant oxygen-containing functional groups in hard carbon by using pre-oxidation anthracite as the precursor combined with controlling the carbonization temperature. The oxygen-containing functional groups in hard carbon can increase the reversible Na+ adsorption in the slope region, and the closed micropores can be conducive to Na+ storage in the low-voltage platform region. As a result, the optimal sample exhibits a high initial reversible sodium storage capacity of 304 mAh g−1 at 0.03 A g−1, with an ICE of 67.29% and high capacitance retention of 95.17% after 100 cycles. This synergistic strategy can provide ideas for the design of high-performance SIB anode materials with the intent to regulate the oxygen content in the precursor. [ABSTRACT FROM AUTHOR]

In order to study the adsorption characteristics of gas and oxygen in coal seams containing ferrous disulfide, the molecular structure model of anthracite and the structural model of ferrous disulfide were constructed respectively, and the adsorption isotherms of ferrous disulfide crystal and anthracite for single component O2 and CH4 were calculated. Based on the experimental data of inorganic sulfur content in coal, the structural models of ferrous disulfide and anthracite were mixed in different proportions, and the structural models of anthracite with inorganic sulfur content of 1.17 %, 2.61 %, 0.75 % and 3.78 % were established, and the adsorption characteristics of O2 and CH4 were calculated and analyzed. The results show that the adsorption rate of single component O2 in FeS2 is higher than that of CH4, which is greatly influenced by pressure and temperature. The binding capacity of O2 with S is stronger than that with Fe, and CH4 is diagonally adsorbed in ferrous disulfide crystal. At 0 ∼ 1 MPa, the adsorption capacity of anthracite for CH4 is greater than that of O2; After 1 MPa, the adsorption rate and capacity of O2 were higher than that of CH4. With the increase of FeS2 content doped with anthracite, the adsorption capacity of CH4 and O2 decreased. When binary components O2 and CH4 are adsorbed on FeS2-doped anthracite, the larger the proportion of O2, the closer the sum of adsorption capacity of mixed gas is to that of single component gas.

The reduction of dust pollution in coal mines is of great importance both for protection of the environment and for the occupational safety and health of coal mine workers. The reduction of dust from anthracite has been a challenge due to its inherent hydrophobicity and high metamorphism. As a result, surfactants are commonly added to water to improve the wettability of coal, thereby improving the dust reduction efficiency of a water spray system. To clarify from a microscopic perspective the effect of different surfactants on the wettability of anthracite, models for the anthracite-surfactant-water system were established, and adsorption configuration, relative concentration distribution, and the diffusion coefficients of water molecules in the systems were thoroughly investigated with molecular simulations. The results showed the directional arrangement of surfactants in the simulation systems after 150 ps of equilibration, resulting in the reduced surface tension of the water-surfactant solution and enhanced wettability of anthracite. Along the (001) normal direction, the relative concentration of sodium dodecylbenzenesulfonate (SDBS) (15.32), the anthracite-water overlapping area, the diffusion rate of water molecules, and the activity (DSDBS = 0.97 × 10-8 m2·s−1) were maximized, indicating the excellent wettability effect of SDBS. The results of the study are of practical significance for improving the wetting effect of anthracite, improving the dust reduction efficiency, and safeguarding the occupational safety and health of personnel.

The scientific understanding of the fluid flow and mass transfer mechanism in pores and fractures of coal seam are the fundamental strategy to achieve the efficient production of coalbed methane (CBM). During CBM development, the occurrence, migration, and production characteristics of coalbed water not only determine the drainage and depressurization effect of CBM well, but also significantly affect the desorption, migration, and production process of CH4, which is crucial to the efficient drainage and production control of CBM well. Taking the Fanzhuang block in the southern Qinshui Basin as an example, based on the occurrence form, production process, and flow form of coalbed water, the research on the mechanism of phase change and mass transfer process of coalbed water has been carried out. The threshold pore diameter of phase change and the mass transfer process of coalbed water in anthracite reservoir under the engineering background have been quantified, and its engineering implications for CBM production have been discussed. The results show that the occurrence state of coalbed water can be changed dynamically, and the fluid pressure difference is the main mechanism of its dynamic change. In the single-phase flow stage of water, the migration of movable water is mainly affected by the surface tension. Under the engineering background, the migration and production of movable water in pores and fractures with macropore (pore diameter > 50 nm) is the precondition of the overall release of coal seam pressure, and lays the foundation for a high and stable production of CBM well. In the gas-water two-phase flow stage, the transformation of bound water (capillary water) to movable water is greatly affected by the wettability of coal, and the interface property and interaction between gas and water. The pressure condition requirements of the transformation of bound water (capillary water) to movable water increase due to the capillary effect. In the bubbly flow and plug flow stage, CH4 desorption promotes the transformation of bound water (capillary water) to movable water in some pores and fractures with mesopore (2−50 nm) scale, which determines the overall release of coal seam pressure. This also indicates that after the CBM well has casing pressure, the overall release of the coal seam pressure is the result of the joint action of the gas and water, and the slow transition from the water production stage to the depressurization and gas production stage is necessary for the high production of the CBM well. The continuous casing pressure holding may lead to early formation of slug flow in pores and fractures with mesopore scale, which is not conducive to the high and stable production of CBM well. Moreover, with the decrease of coal seam pressure, the liquid water in pores and fractures with the equivalent pore size > 40 nm can be vaporized and separated to the gaseous free water, which forms competitive adsorption/desorption with the adsorbed CH4. However the water in pores and fractures with the equivalent pore size < 40 nm is preserve with liquid or transported by wetting migration, and has little influence on the transformation of bound water (capillary water) to movable water in the gas-water two-phase flow stage.

The PAHs transformation in the soils of the coal mining enterprises impact zones and thermal power plants remains poorly studied. In turn, coal mining can be considered as a primary cycle in the production of electricity. One of the main sources of negative environmental impact is the coal mining industry located on the territory of the upland in the south of the East European Plain. The features of PAHs accumulation in the soils of fuel and energy enterprises have been studied on the example of mines impact zones with different service life and the current coal-fired power plant. It was established that, regardless of the period and intensity of the emission source, as well as its current status, the polycyclic aromatic hydrocarbons (PAHs) content in the soils of the impact zones was significantly higher than in the soils of the background territory. The content of low molecular and high molecular weight PAHs in the impact zones soils differed depending on the land use type, as well as the period and intensity of an industrial effect type. The pollutants content of in the soils of all considered impact zones significantly exceeded the background values and according to the low molecular weight PAHs content in the soils, they formed the following decreasing series: Mayskiy ≥ Ayutinsky > Novoshahtinsk > Power station > Background. According the high molecular weight PAHs content, the series changed to: Novoshahtinsk >Mayskiy ≥ Ayutinsky > Power station > Background. Soil pollution markers for enterprises of the fuel and energy complex were identified as pyrene and chrysene, which are part of coal, formed from the hydrocarbon sources. The influence of the power plant was accompanied by the benzo(g,h,i)perylene concentration increase.

Environmental safety depends on the level of energy security development. Combustible minerals play a leading role in ensuring energy security. Solid combustible minerals make up a significant proportion in the total mass of combustible minerals. Currently, there is no single universal classification system for solid combustible minerals. Different countries use different systems for classifying coal by grade. At the same time, depending on the classification system, different sets of indicators are taken into account. The main energy accumulator in solid combustible minerals is carbon and a small amount of hydrogen. The energy of solid combustible minerals is directly dependent on the content of these chemical elements. To evaluate and compare different types of solid combustible minerals and their intraspecific differences, based on the presence of the optimal number of indicators of the main energy carriers, which are carbon and hydrogen, the conversion coefficient into conventional anthracite has been developed. The developed conversion coefficient of solid combustible minerals into conventional anthracite makes it possible to analyze the energy value of different types of solid combustible minerals, deposits, layers of solid combustible minerals, different grades of coal, operation of solid combustible mining enterprises, mining and processing enterprises, plants and factories processing solid combustible minerals, the state and prospects for the development of different levels of energy security. In the environmental safety system, the developed coefficient can be used in the development of computer simulation programs in creating protection systems to prevent combustion, fires and explosions in the extraction, use and processing of solid combustible minerals. The proposed option can serve as an additional variety to generalize and improve the existing classification systems, and to motivate to seek new approaches to further classification of solid combustible minerals

Carbon dioxide (CO2) capture, utilization, and storage (CCUS) is an important pathway for China to achieve its “2060 carbon neutrality” strategy. Geological sequestration of CO2 in deep coals is one of the methods of CCUS. Here, the No. 3 anthracite in the Qinshui Basin was studied using the superposition of each CO2 geological storage category to construct models for theoretical CO2 geological storage capacity (TCGSC) assessment, and CO2 adsorption capacity variation with depth. CO2 geological storage potential of No. 3 anthracite coal was assessed by integrating the adsorption capacity with the static storage and dissolution capacities. The results show that (1) CO2 adsorption capacities of XJ and SH coals initially increased with depth, peaked at 47.7 cm3/g and 41.5 cm3/g around 1000 m, and later decreased with depth. (2) four assessment areas and their geological model parameters were established based on CO2 phase variation and spatial distribution of coal thickness, (3) the abundance of CO2 geological storage capacity (ACGSC), which averages 40 cm3/g, shows an analogous circularity-sharp distribution, with the high abundance area influenced by depth and coal rank, and (4) the TCGSC and the effective CO2 geological storage capacity (ECGSC) are 9.72 Gt and 6.54 Gt; the gas subcritical area accounted for 76.41% of the total TCGSC. Although adsorption-related storage capacity accounted for more than 90% of total TCGSC, its proportion, however, decreased with depth. Future CO2-ECBM project should focus on high-rank coals in gas subcritical and gas-like supercritical areas. Such research will provide significant reference for assessment of CO2 geological storage capacity in deep coals.

Porous material based on residual glass was non-conventionally made using anthracite as a pore-forming agent under the conditions of an oven with oxidizing atmosphere. Water glass as a protective agent for carbon particles avoiding their early oxidation and manganese dioxide (MnO2) as an oxygen-supplier contributed to obtaining cellular glass with excellent physical, thermal, mechanical, and morphological features. The best specimen made by microwave heating at 790 ℃ using 1 % anthracite, 11.5 % water glass, 1.8 % MnO2, and 5 % water allowed creating a product with excellent heat-insulating features (apparent density of 0.21 g·cm-3, heat conductivity of 0.039 W·m-1·K-1), and acceptable compressive resistance (2.3 MPa), the microstructural appearance being homogeneous with uniformly distributed pores with very low dimensions (0.1-0.4 mm).

Anthracite stands as a valuable precursor for carbon materials, owing to its high carbon content. However, producing activated carbon from anthracite presents significant challenges due to its elevated ash content (23–40 wt%) and crystalline nature. The high ash content not only fails to contribute to the activation process but also obstructs pore formation on the carbon surface. To address these challenges, this study explores the preparation of activated carbon from anthracite using KOH activation. This method demonstrates remarkable efficacy in enhancing reactivity beyond the inherent physical properties of anthracite. In contrast to physical activation, the utilization of KOH as a chemical agent substantially enhances the specific surface area, resulting in a production yield of 62% and a specific surface area that reaches up to 1596 m2/g at a KOH/anthracite weight ratio of 4.0. Moreover, rinsing the activated sample with tap water achieves an ash removal rate of about 37.9%, surpassing twice the rate achieved through acid pretreatment (67.0%). A noteworthy observation from this study is the substantial reduction in the content of major ash components, such as silicon (Si) and aluminum (Al), both of which are prominent constituents in anthracite ash. Following KOH activation, their levels decrease by approximately 54% to 65%, respectively. These findings highlight the potential of utilizing available anthracite, even with elevated ash content, as a superior carbon material. Fundamentally, the KOH activation method serves a dual purpose: it effectively reduces ash content and promotes pore creation within a highly alkaline environment. This dual advantage positions the method as a promising approach for the production of top-tier activated carbon. [ABSTRACT FROM AUTHOR]

The poor-reactivity anthracite urgently needs more ways for large-scale and high-quality utilization. Due to the advantage of good fuel adaptability, the circulating fluidized bed (CFB) gasification technology has the potential of high-quality utilization of anthracite. In this paper, one kind of anthracite from Shanxi province, China, was employed to be gasified in a pilot-scale CFB gasifier. It is found that at the operating temperature of 1049°C and oxygen concentration of 60.75%, the gas with a concentration of combustibles of 66% and a low heating value of 7.93 MJ/m3 (at about 25°C and 101.325 kPa) was produced in the CFB gasification process. However, the overall gasification efficiency was not desired because a large amount of gasification fly ash (GFA) escaped and its yield was up to 22%. In this case, the cold gas efficiency was below 48% and the carbon conversion ratio was only 62%. Further analysis reveals that the GFA was featured with a developed pore structure and the specific surface area (SBET) reached 277 m2/g. This indicates such GFA has a potential to use as activated carbon (AC) or AC precursor. Basis on this, steam activation experiments of the GFA produced were conducted to investigate the activation characteristics of GFA and thereby to determine its activation potential. Experimental results indicate that increasing temperature sharply accelerated the activation process, while did not impair the maximum activation effect. After activation, the SBET of GFA maximumly increased by 63%, reaching 452 m2/g. With the progress of activation, the pore structure of GFA presents a three-stage evolution process: development, dynamic balance, and collapse. Such a process can be divided and quantified according to the carbon loss. In order to achieve an optimal activation of GFA, the carbon loss shall be controlled at ~15%. This work provides a new scheme for high-quality utilization of anthracite. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we report the development of a porous activated carbon electrode (PACE) material for supercapacitors, derived from anthracite carbonized at high temperatures in an argon atmosphere. Our approach involves a facile air pre-oxidation process, followed by KOH activation, to significantly enhance the material's specific surface area and porosity. The pre-oxidation treatment effectively increased the specific surface area to 1555.1 m2 g−1, resulting in a large number of micropores and mesopores. Moreover, this treatment effectively modulated the structure of small-to-medium-sized pores (2–4 nm) in the PACE samples, ensuring sufficient charge storage capacity and rapid electrolyte ion transport. The optimal sample, C-Pre-2h, demonstrated remarkable cycling stability, with 100% capacitance retention after 10,000 cycles, and a high specific capacitance of 272.1 F g−1 at 1 A g−1. A symmetric supercapacitor based on C-Pre-2h exhibited a substantial energy density of 10.11 Wh kg−1 at 256 W kg−1, alongside a high power density of 25,641 W kg−1 at 3.16 Wh kg−1. This work presents a cost-effective porous carbon material with exceptional cycling stability and superior performance for supercapacitor applications. [ABSTRACT FROM AUTHOR]

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Abstract This paper addressed the effect of copper acetate on the combustion characteristics of anthracite depending on the fractional composition of fuel and additive introduction method. Anthracite was impregnated with 5 wt% of Cu(CH3COO)2 by mechanical mixing and incipient wetness impregnation. Four anthracite samples of different fraction with d

The fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized via a facile one-pot solvothermal process using coal (Jin 15 Anthracite and Shaerhu lignite) as raw materials and dimethyl formamide (DMF) as the solvent, employing a microwave pyrolysis method. This approach demonstrates remarkable efficacy in the development of nitrogen-doped carbon dots (N-CDs) with a high quantum yield (QY). The N-CDs prepared have strong photoluminescence properties. Moreover, the obtained N-CDs emit blue PL and are easily dispersed in polymethyl methacrylate (PMMA), preserving the inherent advantages of N-CDs and the PMMA matrix. The JN-CDs exhibit a high quantum yield (QY) of 49.5% and a production yield of 25.7%, respectively. In contrast, the SN-CDs demonstrate a quantum yield of 40% and a production yield of 35.1%. It is worth noting that the production yield and quantum yield of coal-based carbon dots are inversely related indices. The lower metamorphic degree of subbituminous coal favors an enhanced product yield, while the higher metamorphic degree of anthracite promotes an improved quantum yield in the product, which may be attributed to the presence of amorphous carbon within it. Consequently, we propose and discuss potential mechanisms underlying N-CD formation.

Here, the fabrication of a new electrode based on providing an electrocatalytic substrate by a newly assembled nanocomposition is reported. Ferric oxide-molybdenum disulfide-anthracite (Fe3O4–MoS2–ANT) modified glassy carbon electrode (GCE) was fabricated by a simple procedure and characterized by scanning electronic microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The modified electrode was used as the sensing device for the voltammetric determination of paraquat (PQ), an important herbicide in environmental water resources. The sensor showed good electrocatalytic activity toward the reduction of PQ. We found that the electrochemical sensitivity and durability of the modified GCE enhance in the presence of ANT. Cyclic voltammetric (CV) and differential pulse voltammetry (DVP) were used and the results showed that the Fe3O4/MoS2/ANT composition provides excellent electrocatalytic response for the determination of PQ. The electrochemical responses of the ANT/MoS2/Fe3O4/GCE were investigated to find optimal conditions of scan rate, pH, type of supporting electrolyte, and response repeatability. A linear response of 0.5–180.0 µM with a correlation coefficient (R2) of 0.997 and a detection limit (LOD) of 0.03 µM of PQ were obtained under the optimized conditions. Reasonable recoveries of PQ were obtained between 93.33 and 101.95% for tested river water samples. [ABSTRACT FROM AUTHOR]

The challenge of how to effectively treat minerals in coal before synthetic graphitization is a practical problem. It is unrealistic to remove minerals completely via physical or chemical methods. So, it is essential to clarify the role of minerals in the synthetic graphitization of coal. Based on the complex mineral composition, the mixture samples consisting of coal and mineral are used to obtain the effect of minerals type and content on the synthetic graphitization of coal. The role of minerals in synthetic graphitization is closely associated with the mineral content and type, as well as the rank. As to the lower-rank anthracite, quartz, kaolinite, and calcite have the role of inhibitor for the yields and defect degrees of corresponding samples after synthetic graphitization derived from the mixtures, but the role of catalyzer for their crystal structure (the degree of graphitization, stacking height, lateral size). The increasing content of quartz, kaolinite, and calcite is harmful for the yield, but useful for the crystal structure and defect degrees; the increasing content of pyrite is harmful for the yield, degree of graphitization, and stacking height, and it is useful for defect degrees. As to the higher-rank anthracite, quartz, kaolinite, and calcite have the role of inhibitor for the yield of corresponding samples after synthetic graphitization, catalyzer for their crystal sizes (stacking height, lateral size), and inertia for their degrees of graphitization. The increasing content of quartz, kaolinite, calcite, and pyrite is harmful for the yield and crystal size. A lower coal rank indicates being more prone to positive mineral effects on synthetic graphitization. The role of minerals in the synthetic graphitization of coal is complex and also represents a coupling relationship with the thermal transformation of anthracite. [ABSTRACT FROM AUTHOR]

Fractal derivatives characterize the accelerated creep phase of the creep process. In this study, based on the fractal order theory, the integer-order derivatives are defined from the spatio-temporal self-similarity phenomenon of the dynamic process using the scale change method, and the viscoplastic model is improved to establish a new creep instantonal model with damage to describe the complete creep phase of anthracite. The effects of damage variables on initial and accelerated creep were investigated by performing graded-loading creep tests. Based on the experimental data, inversions of the model-related parameters were performed, and parameter sensitivities were analyzed. The results show that the proposed model can better characterize the complete creep process of anthracite coal, which verifies the correctness and rationality of the model. The damage content affects the initial and accelerated creep strain under different loading levels, and a specific functional relationship exists between them. The study's findings can provide some reference material for the stability control of anthracite affected by disturbing stresses. [ABSTRACT FROM AUTHOR]

The PAHs transformation in the soils of the coal mining enterprises impact zones and thermal power plants remains poorly studied. In turn, coal mining can be considered as a primary cycle in the production of electricity. One of the main sources of negative environmental impact is the coal mining industry located on the territory of the upland in the south of the East European Plain. The features of PAHs accumulation in the soils of fuel and energy enterprises have been studied on the example of mines impact zones with different service life and the current coal-fired power plant. It was established that, regardless of the period and intensity of the emission source, as well as its current status, the polycyclic aromatic hydrocarbons (PAHs) content in the soils of the impact zones was significantly higher than in the soils of the background territory. The content of low molecular and high molecular weight PAHs in the impact zones soils differed depending on the land use type, as well as the period and intensity of an industrial effect type. The pollutants content of in the soils of all considered impact zones significantly exceeded the background values and according to the low molecular weight PAHs content in the soils, they formed the following decreasing series: Mayskiy ≥ Ayutinsky > Novoshahtinsk > Power station > Background. According the high molecular weight PAHs content, the series changed to: Novoshahtinsk >Mayskiy ≥ Ayutinsky > Power station > Background. Soil pollution markers for enterprises of the fuel and energy complex were identified as pyrene and chrysene, which are part of coal, formed from the hydrocarbon sources. The influence of the power plant was accompanied by the benzo(g,h,i)perylene concentration increase. [ABSTRACT FROM AUTHOR]