Elemental Composition Of Coal Research Articles

Study on the degree of influence of coal chemical structure on its wetting characteristics

The wettability of coal plays a crucial role in determining the effectiveness of mine dust reduction, coal flotation, and coal water slurry preparation. This property is influenced by various factors, including coal structure and liquid properties. To investigate the impact of coal’s chemical properties on its wetting behavior, we employed different experimental to characterize the chemical structures of six types of coal. Utilizing contact angle experiments and gray slope correlation analysis, we determined the correlation between each chemical structure parameter and the wetting characteristics of the coal samples. Our findings revealed that 6#Yangquan anthracite has the lowest wettability and its contact angle is 85.3°. Within the coal’s functional group structure, the CH2 symmetric stretching vibration exhibited the highest correlation (0.944) with coal wetting properties. Regarding the elemental composition of coal, oxygen exhibited a higher correlation with coal-wetting properties (carbonyl oxygen structure, 0.788; phenol hydroxyl and ether oxygen bond, 0.798; carboxyl oxygen structure, 0.734). In the carbon skeleton structure of coal, the protonated aryl carbon exhibited the highest correlation degree of 0.944. These results offer insights into the selection of evaluation indices for assessing the influence of coal wetting characteristics and optimizing the hydrophilic and hydrophobic features of the coal surface.

The dependence of particle size on cell toxicity for modern mining dust

Progressive massive pulmonary fibrosis among coal miners has unexpectedly increased. It would likely due to the greater generation of smaller rock and coal particles produced by powerful equipment used in modern mines. There is limited understanding of the relationship between micro- or nanoparticles with pulmonary toxicity. This study aims to determine whether the size and chemical characteristics of typical coal-mining dust contribute to cellular toxicity. Size range, surface features, morphology, and elemental composition of coal and rock dust from modern mines were characterized. Human macrophages and bronchial tracheal epithelial cells were exposed to mining dust of three sub- micrometer and micrometer size ranges at varying concentrations, then assessed for cell viability and inflammatory cytokine expression. Coal had smaller hydrodynamic size (180–3000 nm) compared to rock (495–2160 nm) in their separated size fractions, more hydrophobicity, less surface charge, and consisted of more known toxic trace elements (Si, Pt, Fe, Al, Co). Larger particle size had a negative association with in-vitro toxicity in macrophages (p < 0.05). Fine particle fraction, approximately 200 nm for coal and 500 nm for rock particles, explicitly induced stronger inflammatory reactions than their coarser counterparts. Future work will study additional toxicity endpoints to further elucidate the molecular mechanism causing pulmonary toxicity and determine a dose–response curve.

Characteristics of migration and speciation of trace elements during co-processing of antibiotic residues in a circulating fluidized bed.

In order to study the emission characteristics of the products during the blending of antibiotic residues in coal-fired power plants, blending tests were performed on a 140 t/h circulating fluidized bed boiler. It was found that during combustion, 64 to 87.6% of Cr, As, and Pb are concentrated in the fly ash, and 11.4 to 35% are concentrated in the bottom ash. Only a small amount of these elements are captured by the desulfurization system or enter the environment. During the material distribution of the desulfurization system, trace elements are mostly concentrated in gypsum. In the desulfurization system, the proportion of Cr, As, Pb, Be, Mn, Co, Ni, Se, and Mo in the gypsum range from 82.8 to 99.9%, and the content has reached the level of ppm. When the blending ratio is controlled within 7%, the blending of antibiotic residues has little effect on the elemental composition of coal. The contents of Cr, Ni, Cu, Zn, and Ba in the products increased by 9.5 to 22.3%. This may mean when the blending ratio is increased, it will be harmful to the environment.

ВПЛИВ РЕЗУЛЬТАТІВ АНАЛІЗУ АНАЛІТИЧНИХ ПРОБ ВУГІЛЛЯ НА ТОЧНІСТЬ ПРОГНОЗУ НЕБЕЗПЕЧНИХ ВЛАСТИВОСТЕЙ ШАХТОПЛАСТІВ

Purpose: to establish possible quantitative errors in determining the values of some indicators of the degree of metamorphism without attracting the content of total moisture and mineral impurities to predict the hazardous properties of coal mine layers during mining. Methodology: based on the use of initial data on the quality indicators and properties of coals for specific coal seams, given in the reference sources, with the subsequent recalculation of the state of samples from their dry ashless or ashless state to the raw state. Comparison of the samples of indicators were determined, respectively, using analytical samples and based on the results of recalculation to the initial state (close to the production state), conclusions were drawn about possible errors in the case of using the analysis results of the analytical samples to predict hazardous properties of mines. Results: The analytical state of the samples for dry ashless state (daf) or wet ashless state (af) does not correspond to the state of coal in the working area of mining operations (r), which most accurately characterizes the manifestation of mine hazardous properties. The indicators of the release of volatile substances during thermal decomposition of coals, which are used to predict the hazardous properties of mine coal seams, do not directly reflect changes in the elemental composition of coals during metamorphic transformations. Methods for preparing analytical samples provide for grinding to small fractions, removing external moisture and enriching to ash content less than 10%, which does not correspond to the state of coal (r) in the mining area. The use of indicators set for dry ashless combustible (organic) mass excludes the possibility of analyzing the influence of moisture and mineral impurities on the manifestation of the hazardous properties of coal seams. The use of such indicators to predict the hazardous properties of mine coal seams can lead to errors in their determination of 45 ÷ 50%. The hazardous properties of coal seams can be adequately characterized only by the combined composition and properties of organic matter and mineral impurities in a state close to the presence of coal in the mining area. Using the example of possible significant errors in the calorific value, in the case of its use to characterize the hazardous properties of coal mine seams, the expediency of scientific substantiation of a set of indicators for a reliable forecast of a specific hazardous property for a specific seam formation was proved. Scientific novelty: hazardous properties of coal seams are reliably predicted on the basis of the composition and properties of organic and mineral components, reduced to conditions close to the state during mining operations. Practical value: the results obtained give grounds to scientifically substantiate the selection of the necessary indicators for predicting a specific hazardous property of coal seams and make proposals for improving the regulatory framework for the safe conduct of mining operations.

Effect of combustion temperature on the emission of trace elements under O2/CO2 atmosphere during coal combustion

The effect of combustion temperature on the emission of trace elementswas studied under O2/CO2 atmosphere during coal combustion in a laboratory scale fluidized bed combustor. The elemental composition of fine fly ash particles collected with a low pressure impactor(LPI)was quantified by X-Ray F1uorescence Spectrometer (XRF). The elemental composition of coal and bottom ash was quantified byinductively coupled plasma-atomic emission spectroscopy (ICP-AES). The results indicate that the contents of Mn, Zn, Cd and Cr in the fly ash increase with the rise of combustion temperature. It is found that the enrichment of Zn and Cd is greater in the submicrometer particles than the supermicrometer particles, but Mn and Cr do not enrich in the submicrometer particles. Mn, Zn, Cd and Cr display one peak around 0.1 μm. The relative enrichment factor (Rij) of four elements is in the order of Zn, Cd, Mn and Cr. Zn and Cd are mostly retained in fly ashwhileMn and Cr are retained in both the fly ash and bottom ash.

Monitoring of arsenic fate with proximate parameters and elemental composition of coal from Thar coalfield, Pakistan

It was extensively studied that combustion of coal for power generation is an important anthropogenic contributor of toxic elements to the environment. In present study the exposure of arsenic (As) from coal samples collected from two sites (III and V) of Thar coalfield before and after burning were evaluated. Meanwhile the proximate parameters and elemental composition of collected coal samples were also studied in detail. The quantitative analysis of As in coal samples and their ash were achieved by microwave-assisted acid digestion methods prior to analyze by MHS-15 hydride generation atomic absorption spectrometry. The contents of As in coal samples of site-III of Thar coalfield was found to be higher as compared to site-V, it may be due to difference in geochemical mineral composition. The resulted data of ash indicated that during combustion of coal >88.5% of As can be released into the atmosphere. The evaluated moisture contents in coal samples of Thar coalfield indicated that the direct use of coal is not suitable for power generation and other activities.

Resources and economic analyses of underground coal gasification in India

India has 298.914billion tonnes of coal resources and 43.215billion tonnes of lignite resources. Underground Coal Gasification (UCG) can be used to extract the deep and un-minable coal and lignite resources in India. Total 120.666billion tonnes coal resources and 20.98billion tonnes lignite resources are confined to the depth greater than 300m which would be the potential resources for UCG. A simple approach has been developed for economic evaluation of UCG project. The UCG module can be considered to consist of two vertical wells. An equilibrium model based on elemental composition of coal is used to predict the gas quality and yield. Based on a single UCG module dimensions, syngas production and power generation per module are calculated. The capital and operating costs are estimated for 100MW UCG power plant with the multiple UCG modules. Three Indian coal samples- one sub-bituminous coal (C) and two lignites (A and B) are used to estimate the capital and operating costs of 100MW UCG power plant. The capital costs are in the range of $210–246millions. The estimated costs of clean syngas production per GJ are $1.34, $0.90 and $1.73 for sample A, B and C respectively. The estimated electricity generation costs per MWh using UCG syngas are $24.27, $19.10 and $28.11 for sample A, B and C respectively.

Use of coal in the Bronze Age in China

People in northern and western China were probably the first in the world to use coal as a source of energy in a consistent way. The ages cluster around 1900–2200 bc in modern day Inner Mongolia and Shanxi provinces. These are areas where near-surface coal is abundant today and woody vegetation was scant in the Bronze Age. Since coal is bulky to transport, it was probably not a cost-effective energy source in areas with abundant wood supply. The sites where coal was first used were probably occupied for a century to a few centuries at most and were associated with Bronze Age societies. The earliest age is about 3490 bc from a house site at Xiahe in Shaanxi Province; however, the coal is not securely tied to the radiocarbon ages and is assumed to have been used at this site sometime after 3490 bc. The elemental composition of modern mine and sedimentary coal in nearby archaeological contexts suggests that coal was used from local sources, and that elemental composition of coal may be a useful tool in identifying site origin of coal.

Pollution of water during underground coal gasification of hard coal and lignite

Groundwater pollution is considered the most serious potential environmental risk related to the underground coal gasification technology (UCG). A variety of hazardous water-born contaminants have been identified during different UCG operations conducted so far, and in some locations long-term groundwater contaminations were observed. Characteristic organic UCG-related pollutions are mostly the phenols, benzene with its derivatives, polycyclic aromatic hydrocarbons, and heterocycles. In the inorganic array, ammonia, cyanides, sulphates, and heavy metals are usually identified. Although the fact that the coal rank affects the contaminants’ formation and release processes during the UCG is known, the information is still scarce. The main goal of the study presented in the paper is the comparison of the processes of formation and release of water contaminants produced during UCG simulations on hard coal and lignite. Significant differences in the qualitative and quantitative description of the contamination profiles were identified for both types of coal. From the analysis it follows that the formation of contaminants is the function of coal rank, the elemental composition of coal, and the gasification temperature. In case of hard coal gasification, the total load of inorganic and organic pollutants in the process water is substantially higher in comparison to lignite. It has been identified that the reaction pH is the parameter affecting concentrations of heavy metals in process waters. The macromolecular structure of coal and temperature were recognized as the main factors governing the distribution of organic compounds. The highly aromatised structure of hard coal becomes the source of substantial quantities of aromatic compounds; still the contribution of smaller species (one or two rings) is high. For lignite, the relative contributions of higher aromatics are greater as compared to hard coal.

Molecular modeling of the structure and properties of coal organic matter

The algorithms and results of molecular modeling of the structure and (physicochemical and processing) properties of coal organic matter (COM) and its components (macerals) based on two approaches, (1) a generalized model of the COM structure and (2) the concept of a self-associated multimer in the COM structure of have been presented. A set of structural parameters characterizing the molecules of organic and hetero-organic compounds that simulate the structure of coals is used in the first approach, and the structure of the organic substance of coal in the second approach is treated as a mixture of superimposed individual components with known values of the properties of interest reflecting the structural features of the organic matter and elemental composition of coal.

04/02202 Elemental composition of coals and anthracitesas a basis for modeling of their properties: Miroshnichenko, D. V. and Ulanovskii, M. L. Koks i Khimiya, 2003, 4, 3–7. (In Russian)

04/02202 Elemental composition of coals and anthracitesas a basis for modeling of their properties: Miroshnichenko, D. V. and Ulanovskii, M. L. Koks i Khimiya, 2003, 4, 3–7. (In Russian)

Elemental composition of coal by using prompt gamma-neutron activation analysis

Prompt gamma-neutron activation analysis, PGNAA, has been used to determine major and minor elements of bituminous coals. Calibration curves for H, C, N, Cl, Si, Ti, Al, Fe, Ca, Na, K, and S were obtained using six coals of different origin. The correlation coefficients are, in general, greater than 0.9 with the exception of C, N, and K. The γ-peak intensities were corrected for volume hydrogen content and normalised to the source intensity by using the 2615 keV γ-line from the (n, n′γ) reaction induced in the lead container of the Cf source. Elemental compositions of new coal samples were determined. In spite of the weak neutron source intensity, the comparison between the elemental concentrations measured by PGNAA and by conventional analysis show good agreement except for N, K, S and Ca.

Interrelationships between coal compositional parameters

Analytical data from a set of 66 coal samples, ranging in rank from lignitic to low-volatile bituminous, were used to define relationships between coal properties. Unusual care was taken in selecting, collecting, preparing and analysing this set of premium samples providing a high degree of confidence in the conclusions obtained. It was found that univariate relationships between properties, which might seem to convey useful information, are generally of limited operational value and can lead to erroneous conclusions. However, multivariate correlations can predict a number of properties. Specific energy, volatile matter yield, and density (by helium pycnometry) can be estimated from the elemental composition according to the following expressions: Btu lb −1 = 145.9% C + 569.6% H − 53.89% O + 43.08% S − 6.3% Ash% VM = −0.408% C + 11.25% H + % O + 1.3% S g ml −1 = 0.01556% C − 0.04117% H + 0.02247% O + 0.02049% S + 0.0208% Ash The standard deviations of the residuals (estimated-experimental) for the above three correlations are 86 Btu lb −1, 1.5% VM and 0.013 g ml −1. The free-swelling index was found to correlate strongly with the oxygen content (for coals containing > 2 wt% oxygen, daf) and the petrographic composition according to the following expression: FSI = 5 + 4.68 f( O) − 0.00395 NPC 2 + 0.0897 NPC − 0.06 LIP where f( O) = sin(0.2513 O daf + 0.9505) NPC = ash weight% + inertinite, volume% mineral- free LIP = liptinite, volume%, mineral- free It is concluded that the elemental composition of coal can predict many physical properties and process responses. The petrographic composition must be considered when predicting plastic properties. Though petrographic composition influences other properties and process responses, microscopically obtained maceral percentages did not prove useful for quantitatively predicting properties or responses.