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1
Wang, Guang Heng, e An Ning Zhou. "Effect of Coal Structure on Mechanical and Thermal Properties of Coal Filled Soy Protein Composites". Advanced Materials Research 236-238 (maggio 2011): 288–91. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.288.
Testo completoAbstract (sommario):
Using different rank coals as filler, coal-soy protein isolate (SPI) composites were prepared by compression molding processing using glycerol as plasticizer. The structure of the coals used were characterized by Fourier transform infrared (FTIR), ultimate analysis, and surface functional group analysis. The effects of coal structure on the mechanical properties, water resistance, and thermal properties were investigated. The results showed that, in different rank coals, the atomic ratio of oxygen to carbon, carboxylic acid groups, phenolic hydroxyl groups, lactone bonds, and aliphatic chains decreased with coal rank. The strength, water resistance, and glass transition temperature of coal-SPI composites decreased with coal rank. Lower ran coal filler with more reactive functional groups caused the composites strong but brittle. While, higher rank coals provide poor mechanical properties for the composites.
2
Morcote, Anyela, Gary Mavko e Manika Prasad. "Dynamic elastic properties of coal". GEOPHYSICS 75, n. 6 (novembre 2010): E227—E234. http://dx.doi.org/10.1190/1.3508874.
Testo completoAbstract (sommario):
Laboratory ultrasonic velocity measurements of different types of coal demonstrate that their dynamic elastic properties depend on coal rank and applied effective pressure. In spite of the growing interest in coal beds as targets for methane production, the high abundance in sedimentary sequences and the strong influence that they have on seismic response, little data are available on the acoustic properties of coal. Velocities were measured in core plugs parallel and perpendicular to lamination surfaces as a function of confining pressure up to [Formula: see text] in loading and unloading cycles. P- and S-wave velocities and dry bulk and dry shear moduli increase as coal rank increases. Thus, bituminous coal and cannel show lower velocities and moduli than higher ranked coals such as semianthracite and anthracite. The [Formula: see text] relationship for dry samples is linear and covers a relatively wide range of effective pressures and coal ranks. However, there is a pressure dependence on the elastic properties of coal for confining pressures below [Formula: see text]. This pressure sensitivity is related to the presence of microcracks. Finally, the data show that coal has an intrinsic anisotropy at confining pressures above [Formula: see text], the closing pressure for most of the microcracks. This intrinsic anisotropy at high pressures might be due to fine lamination and preferred orientation of the macerals.
3
Antoshchenko, М. I., V. Yu Tarasov, О. I. Zakharova e Ye I. Zubtsov. "Research of vitrinite and fusinite coals for predicting geological hazards in coal seams". Мінеральні ресурси України, n. 3 (12 novembre 2020): 45–49. http://dx.doi.org/10.31996/mru.2020.3.45-49.
Testo completoAbstract (sommario):
To establish the necessity of dividing fossil coals into vitrinitic and fusinitic varieties in order to identify the hazardous properties of coal seams during mining.
Methodology. The study of changes in conditional indices in the general ranking series was carried out according to DSTU 25543-2013 separately for the classification indicators of vitrinite and fusinite coals, as well as coal groups not assigned to the considered varieties. Changes in indices in the ranks of classification indicators allow us to identify the distinctive or unifying features of the construction of these series and provide suggestions for improving the regulatory documents of mining operations.
Outcome. The safety of mining in Ukrainian coal mines is regulated by a number of regulatory documents that are based on genetic classification indicators of coal. One of the decisive factors of dividing coals by technological properties is their classification as vitrinitic or fusinitic, which is not taken into account by the regulatory framework when establishing the hazardous properties of coal seams.
The analysis of distinctive properties acquired in the process of metamorphic transformations between vitrinite and fusinite coals has been carried out. It is established that the correlation indices (R2) of the relationship between conditional indexes of Ro, Vdaf and у ranking series with the conditional indices of the general ranking series by brand of coal are practically the same. In terms of Ro, the values of R2 for vitrinitic and fusinite coals were 0,9114 and 0,9221, respectively. Similar results were obtained for the Vdaf indicator, according to which it is impossible to establish differences in the degree of metamorphic transformations between vitrinite and fusinite coals. The characterizing values of the у indicator do not make it possible to establish the direction of change in the properties of coal. The used values of this indicator have a large scatter in the compilation of coal ranking.
Scientific novelty. The nature of change in the classification indicators of industrial classification of coal for identifying the hazardous properties of coal seams in mining operations has been identified.
Practical relevance. The possibility of improving the regulatory framework for safe mining of coal seams by establishing differences in the properties of vitrinite and fusinite coals.
4
Li, Ping, Zhi Xin Wang, Sheng Dan Feng e Li Su. "Study on Ash Fusion Properties of the Ningdong Coal by Coal Blending". Advanced Materials Research 868 (dicembre 2013): 365–69. http://dx.doi.org/10.4028/www.scientific.net/amr.868.365.
Testo completoAbstract (sommario):
Coal blending is widely utilized in coal chemical industry and power plants, and ash slagging propensity, a non-additive property of the pure coals, is difficult to predict and related to its AFTs (ash fusion temperatures). A combustion experimental approach was undertaken to investigate the influence of coal blending ratio on the AFTs of three coal samples Sh-coal, Qi-coal, Que-coal from Ningdong mining areas. The results showed that a nonlinear decrease of the AFTs was obtained with the blending ratios (Sh-coal/Qi-coal or Sh-coal/Que-coal) increasing, the AFTs dropped by 30 °C from 0.5 to 0.8 ratio; the content of Al2O3 can be obviously lowered AFTs. Therefore, coal blending could lower the AFTs evidently. The obtained results in this research can be used in coal gasification process and further theoretical studies.
5
Kumar, Deepak, H. P. Tiwari, Vinod K. Saxena, Binod K. Khullar, Ranjan K. Singh e Sandip K. Bhattachryaa. "Effects of natural weathering on intrinsic properties of coal and coke quality". Metallurgical Research & Technology 116, n. 1 (18 dicembre 2018): 111. http://dx.doi.org/10.1051/metal/2018048.
Testo completoAbstract (sommario):
The degree of weathering of coking coal and its influence on coking potential of coal and coke strength after reaction depends on the various factors viz., climatic conditions, origin and types of coal. Results indicate that weathering of coking coal significantly affects the rheological properties, i.e. free swelling index, maximum fluidity, initial softening temperature, plastic temperature range and maximum expansion. Furthermore, the carbonization study confirms that the deterioration in coke strength after reaction also depends on the type of coals. It is therefore imperative to minimize weathering time of coking coals, and all-out efforts must be taken to cut down the cycle time from mining to its end use for techno-commercial utilization of a particular coal.
6
El-Tawil, Asmaa A., Bo Björkman, Maria Lundgren, Astrid Robles e Lena Sundqvist Ökvist. "Influence of Bio-Coal Properties on Carbonization and Bio-Coke Reactivity". Metals 11, n. 11 (31 ottobre 2021): 1752. http://dx.doi.org/10.3390/met11111752.
Testo completoAbstract (sommario):
Coke corresponds to 2/3–3/4 of the reducing agents in BF, and by the partial replacement of coking coals with 5–10% of bio-coal, the fossil CO2 emissions from the BF can be lowered by ~4–8%. Coking coal blends with 5% and 10% additions of bio-coals (pre-treated biomass) of different origins and pre-treatment degrees were carbonized at laboratory scale and with a 5% bio-coal addition at technical scale, aiming to understand the impact on the bio-coal properties (ash amount and composition, volatile matter content) and the addition of bio-coke reactivity. A thermogravimetric analyzer (TGA) connected to a quadrupole mass spectroscope monitored the residual mass and off-gases during carbonization. To explore the effect of bio-coal addition on plasticity, optical dilatometer tests were conducted for coking coal blends with 5% and 10% bio-coal addition. The plasticity was lowered with increasing bio-coal addition, but pyrolyzed biomass had a less negative effect on the plasticity compared to torrefied biomasses with a high content of oxygen. The temperature for starting the gasification of coke was in general lowered to a greater extent for bio-cokes produced from coking coal blends containing bio-coals with higher contents of catalyzing oxides. There was no significant difference in the properties of laboratory and technical scale produced coke, in terms of reactivity as measured by TGA. Bio-coke produced with 5% of high temperature torrefied pelletized biomass showed a similar coke strength as reference coke after reaction.
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Rudniev, Yevhen, Mykola Antoshchenko, Elvira Filatieva e Julia Romanchenko. "ON THE INFLUENCE OF MINERAL IMPURITIES ON THE MANIFESTATION OF DANGEROUS PROPERTIES OF COAL SEAMS". JOURNAL of Donetsk Mining Institute, n. 2 (2021): 85–95. http://dx.doi.org/10.31474/1999-981x-2021-2-85-95.
Testo completoAbstract (sommario):
Purpose: to establish a possible correspondence between metamorphic processes with artificial thermal destruction of coals and their ashing in order to identify the components of mineral impurities that can affect the manifestation of the hazardous properties of coal mine seams. Methodology is based on a comparison of metamorphic processes that took place at a certain temperature mode in the bowels of the Earth and the production of artificial coals and their ashing. Results: The research made it possible to reveal the important role of mineral impurities in the formation of the hazardous properties of coal seams. This is due to both the significant possible content of mineral impurities in fossil coals, and the simultaneous presence of the main components that determine the hazardous properties of coal seams (carbon, hydrogen, sulfur, oxygen and moisture), both in the organic and in the mineral parts of fossil coals. To improve the regulatory framework for the safe conduct of mining operations, it is necessary to take into account features of the properties of fossil coals due to the presence of mineral impurities in them. In modern regulatory documents on the safe conduct of mining operations, in general, several indicators are used without proper scientific justification: the mass yield of volatiles during the thermal decomposition of coal, the volumetric yield of volatile substances, the thickness of the plastic layer and the logarithm of the electrical resistivity of anthracites. Their values are related to the dry ash-free mass of organic matter only. This excludes consideration of the influence of mineral impurities on the manifestation of the hazardous properties of coal mine seams during mining operations. In many cases, the content of moisture and sulfur is a criterion for the manifestation of hazardous properties of coal seams. They belong to the integral components of both organic and mineral constituents of fossil coals. The share of mineral impurities in the coals of individual coal seams can be more than 40%. The presence of oxygen, hydrogen, sulfur and moisture in mineral impurities significantly affects the manifestation of the hazardous properties of coal seams during mining. The content of mineral impurities in fossil coals in engineering calculations can be determined on the basis of the ash content of coals according to known empirical relationships, corrected for the content of total sulfur and, in some cases, carbon dioxide. Scientific novelty: the significant influence of mineral impurities in fossil coals on the manifestation of hazardous properties of coal seams during mining operations has been proved. Practical value: the results obtained allow substantiating the methodology for the combined use of the composition of organic and mineral components of fossil coals for a reliable forecast of the manifestation of hazardous properties of coal seams and improving the regulatory framework for their safe mining.
8
Steer, Julian, Mark Greenslade e Richard Marsh. "A Comparison of Laboratory Coal Testing with the Blast Furnace Process and Coal Injection". Metals 11, n. 9 (17 settembre 2021): 1476. http://dx.doi.org/10.3390/met11091476.
Testo completoAbstract (sommario):
The injection of coal through tuyeres into a blast furnace is widely adopted throughout the industry to reduce the amount of coke used and to improve the efficiency of the iron making process. Coals are selected depending on their availability, cost, and the physical and chemical properties determined by tests, such as the volatile matter content, fixed carbon, and ash content. This paper describes research comparing the laboratory measured properties of injection coals that were used over a two-month production period compared to the process variables and measurements of the blast furnace during that study period. In addition to the standard tests, a drop tube furnace (DTF) was used to compare the burnout of coals and the char properties against the production data using a range of statistical techniques. Linear regression modelling indicated that the coal type was the most important predictor of the coal rate but that the properties measured using laboratory tests of those coals were a minor feature in the model. However, comparisons of the Spearman’s correlations between different variables indicated that the reverse Boudouard reactivity of the chars, prepared in the DTF from the coals, did appear to be related to some extent to the coal and coke rates on production. It appears that the constant process adjustments made by the process control systems on the furnace make it difficult to identify strong correlations with the laboratory data and that the frequency of coal sampling and the coal blend variability are likely to contribute to this difficulty.
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Nyakuma, Bemgba Bevan, e Aliyu Jauro. "Chemical and Pyrolytic Thermogravimetric Characterization of Nigerian Bituminous Coals". GeoScience Engineering 62, n. 3 (1 dicembre 2016): 1–5. http://dx.doi.org/10.1515/gse-2016-0017.
Testo completoAbstract (sommario):
Abstract The discovery of new coal deposits in Nigeria presents solutions for nation’s energy crises and prospects for socioeconomic growth and sustainable development. Furthermore, the quest for sustainable energy to limit global warming, climate change, and environmental degradation has necessitated the exploration of alternatives using cleaner technologies such as coal pyrolysis. However, a lack of comprehensive data on physico-chemical and thermal properties of Nigerian coals has greatly limited their utilization. Therefore, the physico-chemical properties, rank (classification), and thermal decomposition profiles of two Nigerian bituminous coals – Afuze (AFZ) and Shankodi-Jangwa (SKJ) – were examined in this study. The results indicate that the coals contain high proportions of C, H, N, S, O and a sufficiently high heating value (HHV) for energy conversion. The coal classification revealed that the Afuze (AFZ) coal possesses a higher rank, maturity, and coal properties compared to the Shankodi-Jangwa (SKJ) coal. A thermal analysis demonstrated that coal pyrolysis in both cases occurred in three stages; drying (30-200 °C), devolatilization (200-600 °C), and char decomposition (600-1000 °C). The results also indicated that pyrolysis at 1000 °C is not sufficient for complete pyrolysis. In general, the thermochemical and pyrolytic fuel properties indicate that the coal from both places can potentially be utilized for future clean energy applications.
10
Oskay, R. G., H. Inaner, A. I. Karayigit e K. Christanis. "Coal deposits of Turkey: properties and importance on energy demand". Bulletin of the Geological Society of Greece 47, n. 4 (5 settembre 2013): 2111. http://dx.doi.org/10.12681/bgsg.11106.
Testo completoAbstract (sommario):
In the last two decades electricity generation and consumption in Turkey was increasing steadily. Around 80% of the electricity generated is derived from fossil fuels such as imported natural gas and oil, and domestic coal. As the energy policy now is focusing on reducing the dependency on imported fuels, coal, particularly this of low-rank, is becoming important for the country. Latest explorations showed that total coal reserves of Turkey reach to 13 Gt with low-rank coals (i.e. lignite and sub-bituminous) being dominant. Coal deposits, formed under various conditions and in various geological times, are widely spread over the territory. The most significant deposits are of Tertiary, especially Neogene age. Neogene coals are most appropriate for combustion in the thermal power plants due to the high total reserves despite the high ash yields and the low calorific values. We imply that applying reasonable exploitation planning and appropriate washing techniques, coal will play a key role in future energy supply of the country.
11
Gong, Shuang, Zhen Wang, Lei Zhou e Wen Wang. "Influence of Cyclic Impact Loading and Axial Stress on Dynamic Mechanical Properties of Burst-Prone Coal". Shock and Vibration 2021 (13 gennaio 2021): 1–10. http://dx.doi.org/10.1155/2021/6649308.
Testo completoAbstract (sommario):
High in-situ stress and frequent dynamic disturbances caused by the mining process in deep coal mines can easily induce dynamic disasters such as coal burst. We conducted laboratory experiments to assess the effects of the axial stress loading and dynamic cyclic impact loading on the dynamic mechanical properties of burst-prone coals by using a modified split Hopkinson pressure bar (SHPB). Comparisons were made using two types of burst-prone and burst-resistant coal samples. The mineral components, organic macerals, and dynamic mechanical features of both burst-prone and burst-resistant coal samples were comparatively analyzed based on the obtained X-ray diffraction (XRD), optical microscope observations, and dynamic compressive stress-strain curves, respectively. The results of the microstructure analysis indicated a larger difference between the minimum and maximum reflectances of vitrinite for burst-prone coal. Compared to the burst-resistant coal samples, the burst-prone coals contained less corpocollinite and fusinite. While applying a high axial static load combined with cyclic impact load, the coal samples showed the characteristics of fatigue damage. The results also demonstrated that preaxial stress affected the burst resistance of coal samples. The greater the preaxial stress was, the less the coal samples could withstand the dynamic cyclic impact load. In comparison to the burst-resistant coal sample, the burst-prone coal sample showed a larger dynamic compressive strength and a lower deformation. They were also more positively capable of the propagation and activation of the coal burst. We believe that the results of the study are conducive to further understanding of the distribution of microcomponents of burst-prone coals. The results are also beneficial for realizing the dynamic mechanical characteristics of burst-prone coals under the impact of cyclic dynamic load.
12
Godyń, Katarzyna, Barbara Dutka, Monika Chuchro e Mariusz Młynarczuk. "Synergy of Parameters Determining the Optimal Properties of Coal as a Natural Sorbent". Energies 13, n. 8 (16 aprile 2020): 1967. http://dx.doi.org/10.3390/en13081967.
Testo completoAbstract (sommario):
Selection of the optimal properties of coal as a natural sorbent, both as a sample collected from a seam or of the coal seam itself, requires various parameters to be determined and may not be based on the knowledge of metamorphism degree only. In order to improve the predictions of sorption capacity and the kinetics, analyses of correlation and multiple regression based on the results of laboratory studies were performed for 15 coal samples with various coal rank. The maximum vitrinite reflectance (R0) for low-rank coals was 0.78%–0.85%, and 0.98%–1.15% and 1.85%–2.03% for medium- and high-rank coals, respectively. Coal samples were subjected to technical and petrographic analysis. The gravimetric method was used to perform sorption tests using methane, in order to determine the sorption capacity and the effective diffusion coefficient for each of the coals. Pycnometric methods were used to determine the textural parameters of coals, such as the percentage porosity and specific pore volume. The studies were further supplemented with an evaluation of the mechanical properties of the coals, Vickers micro-hardness, and elastic modulus. This work shows that the statistical multiple regression method enables a computational model including the selected petrophysical parameters displaying synergy with the specific sorption property—capacity or kinetics—to be created. The results showed the usefulness of this analysis in providing improved predictions of the optimal sorption properties of coal as a natural sorbent.
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Singh, Alpana, e B. D. Singh. "Coal Petrology - A shifting role from coal utilization to fuel exploration". Journal of Palaeosciences 57, n. (1-3) (31 dicembre 2008): 257–64. http://dx.doi.org/10.54991/jop.2008.243.
Testo completoAbstract (sommario):
Coal petrology deals with the study of microscopically recognizable remains of vegetal source matter, termed 'macerals', which for convenience are classified and categorized into three main groups- vitrinite (O2-rich), liptinite (H2-rich) and inertinite (C-rich). Each maceral being specific in its origin, evolution and environmental conditions during genesis has tremendous interpretative value. Vitrinite-rich coals form in anaerobic (wet-reducing) condition, whereas aerobic (dry-oxidative) condition results into the formation of inertinite-rich coals. Macerals of the liptinite group originate in acidic-wet conditions of swamp. Optical properties (reflectance and fluorescence) and quantitative estimations of coal micro-constituents overall reflect the chemical properties and thus help in various interpretations. The studies are convincingly utilized to predict the suitability of coal for specific economic and industrial purposes. Currently, the petrological investigations are being utilized to interpret the potentiality of coal for methane that originates during the time and pressure induced diagenetic and catagenetic stages of coal formation.
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Chen, Dezhi, Xinyu Ning, Wen Tang, Jun Xu, Kai Xu, Limo He, Hengda Han et al. "Effects of Parent Coal Properties on the Pyrolytic Char Chemical Structure: Insights from Micro-Raman Spectroscopy Based on 32 Kinds of Chinese Coals". Processes 9, n. 9 (2 settembre 2021): 1575. http://dx.doi.org/10.3390/pr9091575.
Testo completoAbstract (sommario):
The chemical structures of pyrolytic chars prepared from 32 kinds of Chinese coals were investigated with micro-Raman spectroscopy in this study. Both first-order and second-order Raman spectra of the chars were curve-fitted and analyzed. The effects of the parent coal properties, including coal rank, volatile, fixed carbon, and ash content, on the pyrolytic char structures were detailed discussed and the correlations between these coal properties and pyrolytic char chemical structures were set up. Multiple-factor analysis was done to propose a comprehensive coal property index that relates well to the pyrolytic char chemical structure. The results indicate that the aromatization degree is the key distinguishable structure of pyrolytic chars prepared from coals with various rank, and the alkyl C−H and aryl C−H structures have no significant difference. The aromatization degree of pyrolytic char decreases with the increase of coal rank, while it increases with the increase of the fixed carbon content in parent coals. The high content of moisture in parent coal can induce condensation of the pyrolytic char, but the inorganic composition probably prevents the condensation of the char. Limited correlations between the coal rank, fixed carbon, moisture and ash content, and the aromatization degree of pyrolytic chars were found. A comprehensive coal property index: (fixed carbon content + moisture content)/(volatile content + ash content) (in air dry basis) combining the coal properties together relates well to the aromatization degree of pyrolytic char and can act as a good indicator for the pyrolytic char chemical structure. This study reveals the effects of the parent coal properties, including coal rank, fixed carbon, moisture, and ash content, on the pyrolytic char chemical structure, and provides a new comprehensive coal property index to predict the pyrolytic char chemical structure.
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Bielowicz, Barbara, e Jacek Misiak. "The Impact of Coal’s Petrographic Composition on Its Suitability for the Gasification Process: The Example of Polish Deposits". Resources 9, n. 9 (9 settembre 2020): 111. http://dx.doi.org/10.3390/resources9090111.
Testo completoAbstract (sommario):
In this paper, we discuss the impact of the rank of coal, petrographic composition, and physico-chemical coal properties on the release and composition of syngas during coal gasification in a CO2 atmosphere. This study used humic coals (parabituminous to anthracite) and lithotypes (bright coal and dull coal). Gasification was performed at temperatures between 600 and 1100 °C. It was found that the gas release depends on the temperature and rank of coal, and the reactivity increases with the increasing rank of coal. It was shown that the coal lithotype does not affect the gas composition or the process. Until 900 °C, the most intense processes were observed for higher rank coals. Above 1000 °C, the most reactive coals had a vitrinite reflectance of 0.5–0.6%. It was confirmed that the gasification of low-rank coal should be performed at temperatures above 1000 °C, and the reactivity of coal depends on the petrographic composition and physico-chemical features. It was shown that inertinite has a negative impact on the H2 content; at 950 °C, the increase in H2 depends on the rank of coal and vitrinite content. The physicochemical properties of coal rely on the content of maceral groups and the rank of coal. An improved understanding these relationships will allow the optimal selection of coal for gasification.
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Zhang, Yihuai, Maxim Lebedev, Gregory Smith, Yu Jing, Andreas Busch e Stefan Iglauer. "Nano-mechanical Properties and Pore-Scale Characterization of Different Rank Coals". Natural Resources Research 29, n. 3 (18 ottobre 2019): 1787–800. http://dx.doi.org/10.1007/s11053-019-09572-8.
Testo completoAbstract (sommario):
ABSTRACT Characterization of coal micro-structure and the associated rock mechanical properties are of key importance for coal seam exploration, coal bed methane development, enhanced coal bed methane production and CO2 storage in deep coal seams. Considerable knowledge exists about coal chemical properties, but less is known about the nanoscale to the micro-scale structure of coals and how they change with coal strength across coal ranks. Thus, in this study, 3D X-ray micro-computed tomography (with a voxel size of 3.43 µm) and nano-indentation tests were conducted on coal samples of different ranks from peat to anthracite. The micro-structure of peats showed a well-developed pore system with meso- and micro-pores. The meso-pores essentially disappear with increasing rank, whereas the micro-pores persist and then increase past the bituminous rank. The micro-fracture system develops past the peat stage and by sub-bituminous ranks and changes into larger and mature fracture systems at higher ranks. The nano-indentation modulus showed the increasing trend from low- to high-rank coal with a perfect linear relationship with vitrinite reflectance and is highly correlated with carbon content as expected.
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Ma, Shuangwen, Han Liang e Chen Cao. "Laboratory Study of Deformational Characteristics and Acoustic Emission Properties of Coal with Different Strengths under Uniaxial Compression". Minerals 11, n. 10 (29 settembre 2021): 1070. http://dx.doi.org/10.3390/min11101070.
Testo completoAbstract (sommario):
Acoustic emission (AE) can reflect the dynamic changes in a material’s structure, and it has been widely used in studies regarding coal mechanics, such as those focusing on the influence of loading rate or water content change on the mechanical properties of coal. However, the deformational behavior of coals with various strengths differs due to the variation in microstructure. Hard coal presents brittleness, which is closely related to certain kinds of geological disasters such as coal bursts; soft coal exhibits soft rock properties and large deformation mechanical characteristics. Therefore, conclusions drawn from AE characteristics of a single coal sample have application limitations. This paper studies the deformation patterns and AE characteristics of coals with different strengths. A uniaxial compression experiment was carried out using coal samples with average uniaxial compressive strengths of 30 MPa and 10 MPa; the SAEU2S digital AE system was used to measure the AE counts, dissipation energy, and fracturing point distributions at each deformation stage of the different coals. The results show that the bearing capacity of hard coal is similar to that of the elastic stage and plastic deformation stage, but it may lose its bearing capacity immediately after failure. Soft coal has a relatively distinct stress-softening deformation stage and retains a certain bearing capacity after the peak. The AE counts and dissipation energy of hard coal are significantly higher than those of soft media, with average increases of 49% and 26%, respectively. Via comparative analysis of the distribution and development of internal rupture points within soft coal and hard coal at 15%, 70%, and 80% peak loads, it was observed that hard coal has fewer rupture points in the elastic deformation stage, allowing it to maintain good integrity; however, its rupture points increase rapidly under high stress. Soft coal produces more plastic deformation under low loading conditions, but the development of the fracture is relatively slow in the stress-softening stage. We extracted and summarized the AE characteristics discussed in the literature using one single coal sample, and the results support the conclusions presented in this paper. This study subdivided the deformation process and AE characteristics of soft and hard coals, providing a theoretical guidance and technical support for the application of AE technology in coal with different strengths.
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Zhu, Ziqi, Rihong Cong, Lingmei Zhou, Hao Zheng, Yanan Tu e Zhengpeng Wu. "Effects of Chemical Properties and Inherent Mineral Matters on Pyrolysis Kinetics of Low-Rank Coals". Processes 9, n. 12 (24 novembre 2021): 2111. http://dx.doi.org/10.3390/pr9122111.
Testo completoAbstract (sommario):
The kinetics during the pyrolysis process depend on both chemical structure and inherent mineral matters in coal, but normally, only one of these components is investigated in literature. In the present work, four low-rank coals were pyrolyzed in a thermogravimetric analyzer at a heating rate of 10 K/min in a constant nitrogen stream at a temperature up to 900 °C to study the pyrolysis behavior and kinetics. Two of the samples were raw coal (R-YL) and clean coal (C-YL) obtained through the washing process. The results showed that the coal-washing process mainly affected the inorganic part (mineral matters) and structure in coal, which did not largely change the chemical properties. The pyrolysis behavior in primary stage (before 550 °C) was mainly affected by the chemical properties of coal, while the pyrolysis behavior in higher temperature also depended on inherent mineral matters. The kinetics of four coals were obtained using the Coats–Redfern (CR) method with five theoretical models. The difference of E value was almost negligible for R-YL and C-YL, also showing that the coal-washing process did not largely change the chemical properties. The higher frequency factor A for clean coal C-YL showed a more porous structure due to the coal-washing process. The apparent activation energy E in the third stage was affected by the thermodynamic property of inherent minerals.
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Zhao, Yu Ji, Jun Qian Li, Yi Dong Cai, Da Meng Liu e Yan Bin Yao. "Preliminary Evaluation on Physical Properties of Coal Reservoirs in Boli Basin, Northeastern Heilongjiang Province, China". Advanced Materials Research 356-360 (ottobre 2011): 2963–69. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.2963.
Testo completoAbstract (sommario):
The Boli basin has coalbed methane (CBM) resource of 57×108m3 at a coal-bearing area of about 7200km2. Although the basin has huge CBM development potential, the study on the characteristics of coal reservoirs is still deficient. In the paper, the physical properties (including coal petrography, rank, quality, porosity and permeability) of the coals were studied by: (1) measuring vitrinite reflectance, coal maceral composition and coal quality; (2) quantitatively counting microfractures; (3) porosity and permeability tests; and (4) low-temperature N2 isotherm adsorption/desorption and mercury porosimetry analyses. Results show that: (1) coal maceral composition is dominated by vitrinite (77.0-95.1 %); (2) the maximum vitrinite reflectance of coals ranges from 0.48 to 1.76 % Ro, max; (3) coal is composed of high carbon content (63.43-85.14%), low hydrogen content (3.23-4.56%), extremely low moisture content (0.18-1.18%) and widely varied ash yield (7.54 to 29.23%); (4) Coal pores are dominated by micropores (40.6-69.3%), and the pores with a diameter of 0-10nm are dominant (59.6-80.9%); (5) coal permeability values vary from 0.04 to 3.92mD with an average of 1.98mD. In addition, according to the mercury porosimetry analysis, pore-fractures size distribution was summarized as four types: Types Ⅰ and Ⅲ are favorable for developing CBM and represent good pore-fracture structures.
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Nag, Debjani, P. Kopparthi, P. S. Dash, V. K. Saxena e S. Chandra. "Enrichment of reactive macerals in coal: its characterization and utilization in coke making". Metallurgical Research & Technology 115, n. 2 (2018): 209. http://dx.doi.org/10.1051/metal/2017094.
Testo completoAbstract (sommario):
Macerals in coal are of different types: reactive and inert. These macerals are differ in their physical and chemical properties. Column flotation method has been used to separate the reactive macerals in a non-coking coal. The enriched coal is then characterized in order to understand the changes in the coking potential by different techniques. It is then used in making of metallurgical coke by proper blending with other coals. Enriched coal enhance the properties of metallurgical coke. This shows a path of utilization of non-coking coal in metallurgical coke making.
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Reddy, G. V., S. K. Mohapatra e R. K. Sinha. "RHEOLOGICAL PROPERTIES OF COAL OIL MIXTURES: INFLUENCE OF COAL PROPERTIES". Fuel Science and Technology International 12, n. 9 (gennaio 1994): 1257–70. http://dx.doi.org/10.1080/08843759408916233.
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Godyń, Katarzyna, e Barbara Dutka. "Sorption and Micro-Scale Strength Properties of Coals Susceptible to Outburst Caused by Changes in Degree of Coalification". Materials 14, n. 19 (4 ottobre 2021): 5807. http://dx.doi.org/10.3390/ma14195807.
Testo completoAbstract (sommario):
Coals from the south-western part of the Upper Silesian Coal Basin have a strong outburst susceptibility. The objective of this study was to identify the influence of coalification degree on methane sorption and micro scale strength properties of 24 coals from Jastrzębie Zdrój. Coal samples showed a reflectance Ro between 0.98 and 1.25%. Sorption measurements were carried out by gravimetric method. Sorption capacities were determined at mean deposit temperature of 35 °C. Using the unipore model and solution of Fick’s second law, the effective diffusion coefficients of methane in the studied coals were obtained. The Vickers method was used to study the microhardness and the modulus of elasticity. It has been shown that the increase in the coalification degree reduces the sorption capacity of coal and also reduces the rate of methane emission. Coals the most susceptible to outbursts, were the most brittle. With the increase in Ro, the methane seam pressure p increased as well as desorbable methane content DMC, both due to the reduction in the sorption capacity of coal. The increased dp index is a warning sign indicating an increased total methane content of coal seam, an increased seam pressure or an alternation of coal structure.
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Kiryaeva, T. A. "Relationship of the parameters of physico-chemical and sorp-tion processes with the emission of coal beds. part I: on the influence of physical and chemical parameters of natural coals on their metane capacity". Interexpo GEO-Siberia 2, n. 3 (18 maggio 2022): 143–50. http://dx.doi.org/10.33764/2618-981x-2022-2-3-143-150.
Testo completoAbstract (sommario):
This part of the article shows shows that methane capacity is closely related to the physicochemical properties of coals and the physical structure of coal matter: porosity, moisture, ash content, petrographic composition and the release of volatile substances. It was found that the porosity of natural coals weakly depends on the stages of metamorphism and its effect on the methane content of coals can be ignored. Based on the catalogs of the physicochemical properties of coals from the developed deposits of Kuzbass, it is shown that differences in ash content and moisture content of coals have very little effect on their me-thane capacity, and the main strongest influencing factors on the methane capacity of coal were the depth of coal seams and the release of volatiles.
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Yuan, Wenfeng, Xigui Zheng e Niaz Muhammad Shahani. "Optimization of Indirect Fracturing Process Parameters Based on Mechanical Properties of Fractured and Low-Permeability Coal". Geofluids 2022 (7 marzo 2022): 1–16. http://dx.doi.org/10.1155/2022/7436051.
Testo completoAbstract (sommario):
The coal-bed methane (CBM) resources in soft and low-permeability coals are assumed to be as much as 15 × 1012 m3 in China. Indirect fracturing technology can be an effective method to successfully extract methane within soft coals. The key to the success of this technique is to optimize the parameters, such as water injection flow rate and fracture initiation location, so that the hydraulic fracturing parameters enable the fractures to pass through the interface between coal and rock and propagate sufficiently into the coal. This paper focuses on solving the above problems by focusing on discontinuities and plastic characteristics of soft coals. Voronoi polyhedron was used to simulate the discontinuities of coal, and the constitutive relations of ductile fracture-seepage and elastoplastic damage-seepage are, respectively, given to the discontinuities and coal matrix. A numerical model was established based on the above theory to simulate the effect of stress difference Δσ, coal-rock interface friction coefficient fc,r, water injection flow rate i w , and distance between the well and the interface Dop on indirect fracturing fractures. The results show that the HFs area in the coal is positively correlated with Δσ, fc,r, and i w , and it first increases and then decreases with the decrease of Dop. The above results were applied in the Zhaozhuang mine of Qinshui Basin by optimizing Dop = 1 m and iw = 8 m3/min, so that CBM production has been greatly increased. The results can provide theoretical support for the efficient development of CBM in fractured and low-permeability coal seam areas.
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Rudniev, Yevhen, Vyacheslav Galchenko, Elvira Filatieva e Mykhailo Filatiev. "INFLUENCE OF ANALYSIS RESULTS OF ANALYTICAL COAL SAMPLES ON THE PREDICTION ACCURACY OF HAZARDOUS PROPERTIES OF COAL SEAMS". JOURNAL of Donetsk Mining Institute, n. 2 (2021): 176–86. http://dx.doi.org/10.31474/1999-981x-2021-2-176-186.
Testo completoAbstract (sommario):
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.
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Su, Erlei, Yunpei Liang, Lei Li, Quanle Zou e Fanfan Niu. "Laboratory Study on Changes in the Pore Structures and Gas Desorption Properties of Intact and Tectonic Coals after Supercritical CO2 Treatment: Implications for Coalbed Methane Recovery". Energies 11, n. 12 (6 dicembre 2018): 3419. http://dx.doi.org/10.3390/en11123419.
Testo completoAbstract (sommario):
Tectonic coals in coal seams may affect the process of enhanced coalbed methane recovery with CO2 sequestration (CO2-ECBM). The main objective of this study was to investigate the differences between supercritical CO2 (ScCO2) and intact and tectonic coals to determine how the ScCO2 changes the coal’s properties. More specifically, the changes in the tectonic coal’s pore structures and its gas desorption behavior were of particular interest. In this work, mercury intrusion porosimetry, N2 (77 K) adsorption, and methane desorption experiments were used to identify the difference in pore structures and gas desorption properties between and intact and tectonic coals after ScCO2 treatment. The experimental results indicate that the total pore volume, specific surface area, and pore connectivity of tectonic coal increased more than intact coal after ScCO2 treatment, indicating that ScCO2 had the greatest influence on the pore structure of the tectonic coal. Additionally, ScCO2 treatment enhanced the diffusivity of tectonic coal more than that of intact coal. This verified the pore structure experimental results. A simplified illustration of the methane migration before and after ScCO2 treatment was proposed to analyze the influence of ScCO2 on the tectonic coal reservoir’s CBM. Hence, the results of this study may provide new insights into CO2-ECBM in tectonic coal reservoirs.
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Zhou, Jing-Xuan, Chuan-Jie Zhu, Xi-Miao Lu, Jie Ren, Rong-Jun Si e Qing Ye. "Experimental Investigation on the Mechanical Response of Coals to Uniaxial Compression and Low-Speed Dynamic Loading". Shock and Vibration 2021 (6 gennaio 2021): 1–14. http://dx.doi.org/10.1155/2021/8871458.
Testo completoAbstract (sommario):
The surrounding rock of roadways in underground coal mines will lose its stability or even collapse under gas explosions, especially roadways surrounded by coals. The dynamic mechanical properties of coals were tested in order to investigate the dynamic response of coals under gas explosions. The static mechanical properties of coals were also tested as comparison. It is found that the dynamic stress-strain curves showed no obvious pore compaction stage comparing with uniaxial loading. The dynamic compression strength and the elastic modulus are obviously larger than those obtained in the static mechanical properties test, and the dynamic strain shows an obvious hysteresis phenomenon. The ultimate strain and absorbed energy increased linearly with increase of the strain rate. With the increase of dynamic loading, the fragment size of coal cores decreased obviously. The results could provide a reference for the antiexplosion design of the coal roadway.
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Chu, Chia-Ching, Chih-Min Chang, Der-Her Wang e Thou-Jen Whang. "Thermoplastic Properties of Coal and Coal Extract". Energy & Fuels 31, n. 11 (18 ottobre 2017): 11947–53. http://dx.doi.org/10.1021/acs.energyfuels.7b02327.
Testo completo
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Portnov, V. S., S. А. Vizhva, N. V. Reva, А. D. Maussymbayeva e V. М. Yurov. "Physical properties and forecasted resources of Shubarcol coal deposit". Bulletin of the Karaganda University. "Physics Series" 88, n. 4 (30 dicembre 2017): 35–40. http://dx.doi.org/10.31489/2017phys4/35-40.
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Antoshchenko, М., V. Tarasov, R. Zaika, O. Zolotarova e O. Zakharova. "On determining coal classification indicators for establishing dangerous properties of mines". Geo-Technical mechanics, n. 152 (2020): 149–59. http://dx.doi.org/10.15407/geotm2020.152.149.
Testo completoAbstract (sommario):
Currently, more than 20 qualification indicators are known by which degree of metamorphic coal transformations are established. Most of these indicators are designed for determining technological properties with industrial use of coal in mind. Due to sufficient knowledge of the indicators used, industrial classifications are constantly being improved. The modern classification by genetic and technological parameters groups the coals by the grades based on ten indicators. Of these, only one - the mass yield of volatile substances during the thermal decomposition of coal - is used as the main indicator of the manifestation of dangerous properties of coal seams without due scientific justification. Dangerous properties of coal seams during mining include: gas content of coal, a tendency to gas-dynamic phenomena and spontaneous combustion, dust forming ability and explosiveness of coal dust. In industrial classifications, the main indicator is determined for the dry ash-free state of organic matter. Manifestation of dangerous properties of coal seams occurs in the presence of both moisture and mineral impurities. This fact is not taken into account by other auxiliary indicators used to predict the hazardous properties of coal seams. Moisture in coal seams is in at least four states, and it is completely removed while analyzing the samples and is not taken into account in volatile products of thermal decomposition of coal. Thus, when using the indicator of mass output of volatile substances, influence of moisture in any form of its presence in coal on the occurrence of emergency situations is automatically ignored. The probability of emergencies during mining is largely determined by the ratio between components of organic mass (C, O, H, S, N) and mineral impurities. It is also not taken into account in normative documents which regulate safety of coal seam mining. The classification indicators defined in different ways characterize different aspects of coal conversion in metamorphic processes. Volatiles yield and average vitrine reflectance, well studied in industrial applications, correspond to different aspects of degree of conversion of starting organic matter. In order to establish dangerous properties of coal seams, their mutual substitution is unacceptable, which is confirmed by nonlinear connection between them. The existence of a genetic relationship between the outburst and fire hazard of coal seams has been established. This indicates the need to develop a unified classification of the hazardous properties of coal seams by genetic, mining engineering and geological parameters. The scientifically substantiated use in regulatory documents of a set of classification indicators that directly characterize the manifestations of the hazardous properties of coal seams will help to reduce number of accidents and injuries in coal mines.
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Medyanik, N. L., E. R. Mullina, O. A. Mishurina, N. V. Derina e A. A. Turlina. "Estimation of a possibility to use the quantumchemical approach while selecting reagents for coals flotation intensification". Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 75, n. 5 (20 giugno 2019): 577–82. http://dx.doi.org/10.32339/0135-5910-2019-5-577-582.
Testo completoAbstract (sommario):
Decrease of mined coal quality results in deterioration of main quality characteristics of coal concentrates: ash content, moisture, calorific efficiency and sintering ability. Application of selective reagent modes of coals flotation is an effective method of solving the problem. Elaboration of the reagent modes should be based on a study of mechanism of reagents action on the coal surface. Study of the aromatic esters effect on the physicochemical and flotation properties of gas coals from the Komsomolets mine of the Kuznetsk coal basin accomplished. It was shown that the low natural floatability of gas coals is due to the significant energy unsaturation of their surface, in particular, the presence of large pores, oxygen-containing groups and mineral impurities. The results of quantum chemical calculations demonstrate that the electrophilic centres of the coal are formed due to the electron density shift to the oxygen atoms. It was determined that the hydrophobization of the coal surface can be achieved using reagents that have more rigid nucleophilic nature compared to water molecules. The study of the quantum-chemical characteristics of aromatic esters suggests that they can interact with electrophilic areas of the organic mass of coal through a charge-controlled mechanism with the formation of charge transfer complexes. Results of the study of the aromatic esters effect on the physicochemical properties of coals surface and calculation of quantum-chemical characteristics of compositions, simulating the organic coals mass and studied reagents, allow to make a conclusion about possibility to intensify the coals flotation process based on application the quantum-chemical approach at the reagents selection.
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Yuliani, Galuh, Imas Noviyana e Agus Setiabudi. "Enrichment of Indonesian Low Rank Coal's Surface Oxygen Compounds (SOCs) Using Hydrogen Peroxide and its Adsorptive Properties". Advanced Materials Research 896 (febbraio 2014): 159–62. http://dx.doi.org/10.4028/www.scientific.net/amr.896.159.
Testo completoAbstract (sommario):
Cheap and highly abundant low rank coal from Banten, West Java, Indonesia, was utilized as an adsorbent for a cationic dye. The previous reports show that raw low rank coal has low adsorption capacity when compared to activated carbon. It is also indicated that the coals surface oxygen compounds played a major role in the adsorption mechanism. This research aimed to enrich the oxygen compounds on the coals surface by a straightforward oxidation process using hydrogen peroxide and to investigate the adsorption capacities of raw and treated coals using cationic dye solutions. The oxidation process was conducted by adding the raw coal in hydrogen peroxide solutions having concentrations of 5%, 10%, and 20%, followed by stirring for 10 minutes to 60 minutes. After a serial of washing processes and air-drying, the adsorption capacities of the treated coals for a cationic dye were investigated using batch tests. The batch tests were conducted by adding 0.1 to 0.3 g of coals to 50 mL of methylene blue solutions followed by stirring the solutions for 5 hours. The experimental data were plotted using Langmuir adsorption isotherm model. The adsorption capacity of a treated coal when plotted using Langmuir isotherm was found to be 103 mg/g, significantly higher than that of the raw coal, which was only 52 mg/g. The FTIR spectra showed new absorption of carboxylates at 1700 cm-1 indicating increases in the oxygen containing groups, whilst the surface area measurement indicated an increase in surface area from 0.097 m2/g to 0.232 m2/g. It is concluded that the treatment using hydrogen peroxide solution has significantly improved the surface oxygen compounds of the low rank coal, increased its surface area and also its adsorption capacity for a cationic dye.
33
Rudniev, Ye S., A. M. Galchenko, V. Yu Tarasov e M. I. Antoshchenko. "Moisture as an indicator of the manifestation of hazardous properties of coal seams". Geofizicheskiy Zhurnal 44, n. 3 (24 agosto 2022): 66–79. http://dx.doi.org/10.24028/gj.v44i3.261969.
Testo completoAbstract (sommario):
Purpose: establish the change in the ratios between individual types of moisture and indicators of metamorphic transformations of coal seams after recalculating their values for the working state of the fuel. This will make it possible to predict the manifestation of hazardous properties mining.
Methodology: provides for the involvement of the initial experimental data that have been accumulated in normative and reference documents.
Results: When conducting research, the experience of using moisture as an indicator for solving three problems at once was taken into account: the criterion for evaluating the metamorphic transformations of coal seams; determination of fuel quality; forecast of the manifestation of hazardous properties of coal seams during mining operations. Different types of moisture at different stages of metamorphic transformations of coal seams are not equivalent in terms of the strength of the bond between water and coal. In some regulatory documents, in some cases, indicators of different types of moisture are used to characterize the moisture content of coal seams, which introduces additional errors in the reliability of the prediction of hazardous properties. In the early and middle stages of metamorphic transformations of coal seams, moisture is not formed for the most part, but only free moisture is mechanically removed from the system. Hard coals and anthracites have different molecular structure, which determines different ratios between the content of free and bound moisture. The content of total moisture is a metamorphic indicator only for organic (combustible) mass, and it is not a reliable criterion for assessing the transformation of coal seams in general. Mandatory pre-moistening of coal in the array in all cases during mining operations is not sufficiently substantiated for different stages of metamorphic transformations of coal seams due to the different ratio between the forms of moisture and the irreversibility of metamorphism processes.
Scientific novelty: for the first time, a quantitative assessment of the content of hydrated moisture in mineral impurities and moisture in the organic mass from the degree of metamorphic transformations of coal seams was made.
Practical value: the research results make it possible to develop proposals for improving the regulatory framework in terms of predicting the manifestation of hazardous properties of coal seams during mining operations, depending on the presence of different forms of moisture in coals.
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Kieush, Lina, Andrii Koveria, Johannes Schenk, Kanay Rysbekov, Vasyl Lozynskyi, Heng Zheng e Azamat Matayev. "Investigation into the Effect of Multi-Component Coal Blends on Properties of Metallurgical Coke via Petrographic Analysis under Industrial Conditions". Sustainability 14, n. 16 (11 agosto 2022): 9947. http://dx.doi.org/10.3390/su14169947.
Testo completoAbstract (sommario):
The coalification rank of the coal blend components and their caking properties initially impact the coke’s quality. In part, the quality of coke depends on the technological parameters of the coke production technology, such as the method of blend preparation, the coking condition, the design features of the coke ovens, and the technique used for post-oven treatment. Therefore, to improve the coke quality, the main attention is paid to the quality of the coal blend. The petrographic analysis is the simplest and most reliable way to control coal quality indicators under industrial conditions. In this paper, the effect of nine industrial blends on coke quality using petrographic analysis has been studied. Additionally, this paper addresses the efficient use of coals and the preparation of coal mixtures under industrial conditions, which contributes to the sustainability of cokemaking. For the preparation of blends, 17 coals were used, for which, in addition to petrographic and proximate analyzes, the maximum thickness of the plastic layer was determined. Industrially produced cokes were analyzed for coke reactivity index (CRI), coke strength after reaction with CO2 (CSR), and Micum indices (M25 and M10). It has been established that the petrographic properties of coal blends are reliable parameters for assessing the quality of coke under conditions of an unstable raw material base, multi-component blends, and changes in coking regimes. Moreover, the research results have shown that to ensure the rational use of coals in the preparation of coal blends to achieve the required coke quality and consequently the sustainability of cokemaking, it is necessary to consider not only the mean reflectance of vitrinite but the proximate and caking properties of coals.
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Saxena, Rakesh, G. K. B. Navale, D. Chandra e Y. V. S. Prasad. "Spontaneous combustion of some Permian coal seams of India: An explanation based on microscopic and physico-chemical properties". Journal of Palaeosciences 38 (31 dicembre 1989): 58–82. http://dx.doi.org/10.54991/jop.1989.1641.
Testo completoAbstract (sommario):
Spontaneous combustion of coals is a well-known phenomenon in the coal mines of Raniganj and Jharia coalfields. Although several explanations have been given for this burning problem, yet, no general consensus has reached because of variable laboratory techniques. 1n the present paper, a viable explanation is given for auto-oxidation of coal integrating the microscopic and physico-chemical properties.
Organic petrological investigations of the Permian coal seams reveal vitric and fusovitric petrographic facies corresponding to the Late and Early Permian time, respectively. The characteristic micropetrographic, thermal and chemical properties of the Raniganj coal seams show high to moderate susceptibility to spontaneous combustion. The high amount of the reactive resin/hydrocarbon was found to be closely associated with these coal seams, apart from perhydrous Vitrinite having low rank values. In contrast, the Barakar coal seams show least susceptibility probably because of the absence of reactive resin/hydrocarbon with higher rank values.
Microspectrofluorimetric studies suggest green, yellow and orange varities of reactive resin, hydrocarbons in which green and yellow probably correspond to lipid and terpene fraction, of resins imparting more hydroaromatic and unsaturated aromatic structures to these coal in response to their coalification stage. The strong peak at 1600 ± 50 cm in infrared spectrographs of coal also suggests, the presence of resin content in Raniganj coals which are rich in C =C, C =0 structures. These unsaturated structures play a key role in oxygen-coal reaction leading to the development of an unstable peroxy complex which later through chain mechanism oxidizes the coal while Barakar coals show rigid structural configuration.
The chemical and thermal characteristic vis-a-vis. petrographic composition of these coal seams show conformity in the formation of peroxy complex and its relation with crossing point temperature values. Their crossing point temperature data also suggest conformity in trends with the quantitative distribution of the resin hydrocarbon contents on mmf basis. The endothermic and exothermic peaks and their breakdown steps revealed by differential thermal analysis and derivative thermogravimetric analysis indicate close correspondence with the coal seams of the Raniganj Formation.
Thus, it is presumed that the reactive resin content and expulged hydrocarbons from perhydrous vitrinite and organic matrix filled along the cracks, seem to be the main reactive sites for oxygen reaction in spontaneous combustion.
36
Ariunaa, A., J. Narangerel, B. Purevsuren e R. Erdenechimeg. "Activated carbons from Mongolian coals by thermal treatment". Mongolian Journal of Chemistry 12 (24 settembre 2014): 60–64. http://dx.doi.org/10.5564/mjc.v12i0.174.
Testo completoAbstract (sommario):
Mongolian different rank coals were used as raw material to prepare activatedcarbons by physical activation method. The coal derived carbons were oxidized with nitric acid in order to introduce surface oxygen groups. The ultimate elemental analysis, scanning electron microscopy, surface area, pore size distribution analysis and selective neutralization method were used to characterize the surface properties of activated carbons, oxidizedcarbons and raw coals. The effect of coal grade on the adsorption properties of the carbons were studied. It was concluded that Naryn sukhait bituminous coal could be serve as suitable raw material for production of activated carbons for removal of heavy metal ions from solution.DOI: http://dx.doi.org/10.5564/mjc.v12i0.174 Mongolian Journal of Chemistry Vol.12 2011: 60-64
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Niedoba, Tomasz, e Dariusz Jamróz. "VISUALIZATION OF MULTIDIMENSIONAL DATA IN PURPOSE OF QUALITATIVE CLASSIFICATION OF VARIOUS TYPES OF COAL / WIZUALIZACJA WIELOWYMIAROWYCH DANYCH W CELU KLASYFIKACJI JAKOŚCIOWEJ RÓŻNYCH TYPÓW WĘGLA". Archives of Mining Sciences 58, n. 4 (1 dicembre 2013): 1317–31. http://dx.doi.org/10.2478/amsc-2013-0091.
Testo completoAbstract (sommario):
Abstract Coal as energetic raw material features by many parameters determining its quality. In classification of coal types there are many of them with typical division of energetic, semi-coking and coking coal. The data concerning coal are usually treated as independent values while this kind of approach is not always right. Authors proposed new solutions in this aspect and performed the multidimensional analysis of three selected types of coal featuring by various properties which originated from three various hard coal mines located in Upper Silesia Region. The object of the research was so-called raw coal which was not processed before. For each type of coal the detailed statistical analysis of seven chosen properties of coal was performed. To perform adequate and complete statistical analysis it is necessary to analyze the chosen properties of coal together in multidimensional way. It was decided to apply new and modern visualizing methods of multidimensional data which were observational tunnels method and parallel coordinates method. The applied methods allowed to obtain visualization of seven-dimensional data describing coal. By means of these visualizations it was possible to observe the significant division of the features space between researched types of coal. These methods allowed to look at the investigated data from various perspectives and make possible to determine significant differences between researched materials. For the investigated coals such differences were determined clearly what proved that by means of these methods it is possible to successfully identify type of coal as well to analyze in details its individual properties and identify, for example, particle size fraction etc. The obtained results are innovative and are the basis for more detailed researches taking into consideration also other coal properties, including its structure and texture. This methodology can be also applied successfully for other types of raw materials, like ores.
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Chuchalina, A. D., A. S. Shirkunov, E. А. Farberova e V. G. Ryabov. "Production of High-Quality Extruded Activated Carbons with Simultaneous Decrease of Solid Waste Production". Ecology and Industry of Russia 22, n. 12 (4 dicembre 2018): 33–37. http://dx.doi.org/10.18412/1816-0395-2018-12-33-37.
Testo completoAbstract (sommario):
The purpose of the study was to assess the effect of the metamorphism degree of coal dust on the properties of the produced extruded activated carbon, as well as the possibility of involving a by-product of granular activated carbon production for the purpose of its utilization. In the study, the coals of the Kuznetsk coal basin of the brands Brown Coal, Gas Coal, Weakly Caking Coal (SS(3SS) and SSOM), Lean Coal and Anthracite were analyzed. The optimal coal raw material, namely Weakly Caking Coal of the Bachatsky coal cut SS(3SS), was determined. The study of the effect of the coal grinding degree on the properties of the produced sorbent led to the conclusion that the content of the target fraction (0.1–40 μm) to 79 ± 0.5% in coal dust results in production of extruded activated carbon that meets all requirements of standard. The involvement of lean coal brand TPK – a by-product of granular activated carbons production – with weakly caking coal brand SS (3SS) with 1:1 ratio leads to a decrease of cost of obtained sorbent, as well as to improvement of some of its characteristics.
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Biswas, A., T. Ahmed, K. W. Johnson, K. L. Telschow, J. C. Crelling e J. M. Myers. "Thermal characterization of coal using piezoelectric photoacoustic microscopy". Canadian Journal of Physics 64, n. 9 (1 settembre 1986): 1184–89. http://dx.doi.org/10.1139/p86-206.
Testo completoAbstract (sommario):
The organic constituents that make up the heterogeneous coal mass are called macerals. Vitrinite and pseudovitrinite are two of the most abundantly occurring macerals in North American coals. Photoacoustic microscopy using piezoelectric detection offers a useful technique for probing the thermal-elastic properties of these coal macerals. The experimental and theoretical conditions under which photoacoustic microscopy can be used to characterize the in situ thermal-elastic properties of macerals, as a function of the percentage of carbon or "rank" of coal, are investigated in this paper. Existing piezoelectric photoacoustic theory has been applied to our sample–transducer configuration to arrive at an expression for the voltage measured from the piezoelectric transducer. The theory indicates that the photoacoustic signal is related to the following sample properties: coefficient of thermal expansion a, bulk modulus B, density ρ, and specific heat c. These properties are coupled together into a dimensionless parameter given by aB/ρc, to which the measured voltage is proportional. Some experimental results used to test the validity of the theoretical predictions are presented. Photoacoustic data gathered on 10 Appalachian Basin coals are plotted as a function of the coal rank. These results are shown to compare favourably with a calculated curve, constructed using independently measured values of a, B, ρ, and c.
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Yang, Jian Guo, Xiao Long Zhang e Hong Zhao. "Predicting Ash Fusibility of Coal from Coal Properties". Advanced Materials Research 354-355 (ottobre 2011): 216–21. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.216.
Testo completoAbstract (sommario):
It is significant for safe operation and energy saving to foreknow ash fusibility of coal. Ash fusibility of coal was divided into three levels according to softening temperature. The fusibility level was correlated with coal properties by a nonlinear classified model which was built using support vector machine. The model receives coal properties as input variables and would give a judgment of fusibility level as an output. Validation of the nonlinear classified model on 62 training samples yielded 100% accuracy. The prediction accuracy of 15 testing samples was 86.7%. Results indicate that the level of ash fusibility can be accurately predicted from coal properties with the nonlinear classified model.
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Tailakov, O. V., M. P. Makeev, A. N. Kormin e A. I. Smyslov. "Development of Method of Rapid Analysis of Particle Size Distribution of the Coal Charge Based on Digital Image Processing". Applied Mechanics and Materials 770 (giugno 2015): 512–17. http://dx.doi.org/10.4028/www.scientific.net/amm.770.512.
Testo completoAbstract (sommario):
Therein algorithms of application of digital models for evaluation of porosity and fractional composition of coals based on analysis of their optical images are offered. The models allow allocating significant informational objects and estimation of structural and filtration properties of coals. The results of algorithms application on recognition of the optical images of coals are presented, the particle size distribution of coal charge and porosity of coal is defined.
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Брожко, Ростислав, Михайло Філатьєв, Ельвіра Філатьєва, Микола Антощенко e Євген Руднєв. "ТЕРМІЧНА ДЕСТРУКЦІЯ ВУГІЛЛЯ, МЕТАМОРФІЗМ ШАХТОПЛАСТІВ ТА ЇХ НЕБЕЗПЕЧНІ ВЛАСТИВОСТІ". European Science, sge10-02 (30 aprile 2019): 162–98. http://dx.doi.org/10.30890/2709-2313.2022-10-02-010.
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Miroshnichenko, D. V., V. V. Koval, S. V. Fatenko e Y. V. Nikolaichuk. "Crushing Properties of Coal 2. Binary Coal Blends". Coke and Chemistry 63, n. 11 (novembre 2020): 513–18. http://dx.doi.org/10.3103/s1068364x20110046.
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Gagarin, S. G., e Yu I. Neshin. "Coking properties of coal pitch in coal batch". Coke and Chemistry 54, n. 9 (settembre 2011): 339–42. http://dx.doi.org/10.3103/s1068364x11090031.
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Hower, J. C. "Interrelationship of coal grinding properties and coal petrology". Mining, Metallurgy & Exploration 15, n. 3 (agosto 1998): 1–16. http://dx.doi.org/10.1007/bf03403218.
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Yang, Fan, Lan, Li, Wang, Luo e Zhang. "Dynamic Mechanical and Microstructural Properties of Outburst-Prone Coal Based on Compressive SHPB Tests". Energies 12, n. 22 (6 novembre 2019): 4236. http://dx.doi.org/10.3390/en12224236.
Testo completoAbstract (sommario):
Understanding the dynamic mechanical behaviors and microstructural properties of outburst-prone coal is significant for preventing coal and gas outbursts during underground mining. In this paper, the split Hopkinson pressure bar (SHPB) tests were completed to study the strength and micro-structures of outburst-prone coal subjected to compressive impact loading. Two suites of coals—outburst-prone and outburst-resistant—were selected as the experimental specimens. The characteristics of dynamic strength, failure processes, fragment distribution, and microstructure evolution were analyzed based on the obtained stress-strain curves, failed fragments, and scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) images. Results showed that the dynamic compressive strength inclined linearly with the applied strain rate approximately. The obtained dynamic stress-strain responses could be represented by a typical curve with stages of compression, linear elasticity, microcrack evolution, unstable crack propagation, and rapid rapture. When the loading rate was relatively low, fragments fell in tension. With an increase in loading rates, the fragments fell predominantly in shear. The equivalent particle size of coal fragments decreased with the applied strain rate. The Uniaxial compressive strength (UCS) of outburst-prone coal was smaller than that of resistant coal, resulting in its smaller equivalent particle size of coal fragments. Moreover, the impact loading accelerated the propagation of fractures within the specimen, which enhanced the connectivity within the porous coal. The outburst-prone coal with behaviors of low strength and sudden increase of permeability could easily initiate gas outbursts.
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Rudniev, Ye. "TO THE QUESTION OF SCIENTIFIC SUBSTANTIATION OF THE CHOICE OF INDICATORS OF MANIFESTATION OF HAZARDOUS PROPERTIES OF COAL SEAMS". Municipal economy of cities 4, n. 171 (17 ottobre 2022): 142–57. http://dx.doi.org/10.33042/2522-1809-2022-4-171-142-157.
Testo completoAbstract (sommario):
The article recalculates the quality indicators of coal for their working condition, taking into account the yield of ash and moisture content for coal seams, followed by an analysis of changes in the correlations between the indicators. The need to consider the fuel for its working condition is due to different end goals between establishing the consumer qualities of coal and the manifestation of the hazardous properties of coal seams. Different ultimate goals of the problems under consideration imply different ways of solving them, including differences between the influencing factors and their parameters. The methodology provides for the achievement of the goal to use the initial experimental data that have been accumulated over several decades based on the experience of using coal for industrial purposes. The condition and quality of coal after its preparation for use differs significantly from the condition in the mining area. These differences are associated with the preliminary enrichment of coal and the removal of a certain amount of mineral impurities. Based on conducted research out, the features of the choice of indicators of metamorphic transformations of coals were established, which are used in parallel, respectively, to establish the quality of fuel and predict the hazardous properties of coal seams. Discrepancies between the indicators of the degree of metamorphism used in the current regulatory framework for the safe conduct of mining operations and the state of fuel during mining operations in underground conditions are revealed. To improve normative documents on safe mining operations, it is necessary to consider indicators that characterize not only the organic (combustible) part of the fuel, but also the presence of mineral impurities and moisture in coals in the mining area. Keywords: coal, metamorphism, indicators, justification, mineral impurities, ratio, condition, dry, ashless, working, coal seams, mining, safety, regulatory framework, improvement.
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Miroshnichenko, D. V. "Crushing properties of coal". Coke and Chemistry 56, n. 12 (dicembre 2013): 449–55. http://dx.doi.org/10.3103/s1068364x13120090.
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Marland, S. "Dielectric properties of coal". Fuel and Energy Abstracts 43, n. 4 (luglio 2002): 232. http://dx.doi.org/10.1016/s0140-6701(02)86041-6.
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Marland, S., A. Merchant e N. Rowson. "Dielectric properties of coal". Fuel 80, n. 13 (ottobre 2001): 1839–49. http://dx.doi.org/10.1016/s0016-2361(01)00050-3.
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