scholarly journals The Influence of the Sample Preparation on the Result of Coal Propensity to Spontaneous Combustion in the High-temperature Adiabatic Method

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Dariusz OBRACAJ ◽  
Marek KORZEC ◽  
Tien Tung VU
Keyword(s):  
High Temperature ◽  
Coal Seam ◽  
Spontaneous Combustion ◽  
Spontaneous Heating ◽  
Mine Fire ◽  
Mine Fires ◽  
Technical Factors ◽  
Spontaneous Combustion Of Coal ◽  
Seam Mining ◽  
Very High

The liability of coal to spontaneous combustion is the principal cause of mine fires. Spontaneouscombustion is one of the main threats in Polish and Vietnamese coal mines. The article presents an analysisof the spontaneous combustion of coal in mines of both countries. It is related to the natural prone of coalto spontaneous heating and consequently to its self-ignition. Despite the relevant recognition of themethods of preventing this threat, in mines, spontaneous combustion occurs during the exploitation ofcoal seams with low and very high self-ignition tendency. Apart from the technical factors related to thedesign of coal seam mining, the properties of coal have a significant impact on the occurrence ofspontaneous combustion. Their correct recognition is essential to the precautions against spontaneouscombustion for minimalizing the risk of a mine fire. Therefore, it is necessary to study the factorsinfluencing the propensity of coal to spontaneous heating. A review of the methods used to determine thepropensity of coal to spontaneous combustion is presented in the article. Based on the high-temperaturemethod of determining the propensity of coals to spontaneous combustion, the influence of selectedfactors related to samples' preparation for testing on the determination result was investigated. Theinfluence of the fractional decomposition and the moisture content in the prepared samples on thedetermination result was demonstrated. The presented research results may improve research proceduresfor determining the propensity of coal to spontaneous combustion.

scholarly journals Investigation of the kinetics of spontaneous combustion of the major coal seam in Dahuangshan mining area of the Southern Junggar coalfield, Xinjiang, China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Shen ◽  
Qiang Zeng
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Coal Seam ◽  
Spontaneous Combustion ◽  
Heating Temperature ◽  
Characteristic Temperature ◽  
Mining Area ◽  
Particle Sizes ◽  
Coal Oxidation ◽  
Increasing Temperature

AbstractIn the present paper, with using diverse methods (including the SEM, the XRD, the TPO, the FTIR, and the TGA) , the authors analysed samples of the major coal seam in Dahuangshan Mining area with different particle sizes and with different heated temperatures (from 50 to 800 °C at regular intervals of 50 °C). The results from SEM and XRD showed that high temperature and high number of pores, fissures, and hierarchical structures in the coal samples could facilitate oxidation reactions and spontaneous combustion. A higher degree of graphitization and much greater number of aromatic microcrystalline structures facilitated spontaneous combustion. The results from TPO showed that the oxygen consumption rate of the coal samples increased exponentially with increasing temperature. The generation rates of different gases indicated that temperatures of 90 °C or 130 °C could accelerate coal oxidation. With increasing temperature, the coal oxidation rate increased, and the release of gaseous products was accelerated. The FTIR results showed that the amount of hydroxide radicals and oxygen-containing functional groups increased with the decline in particle size, indicating that a smaller particle size may facilitate the oxidation reaction and spontaneous combustion of coal. The absorbance and the functional group areas at different particle sizes were consistent with those of the heated coal samples, which decreased as the temperature rose. The results from TGA showed that the characteristic temperature T3 declined with decreasing particle size. After the sample with 0.15–0.18 mm particle size was heated, its carbon content decreased, and its mineral content increased, inhibiting coal oxidation. This result also shows that the activation energy of the heated samples tended to increase at the stage of high-temperature combustion with increasing heating temperature.

scholarly journals Prediction Model for Spontaneous Combustion of Coal around Boreholes Using Bedding Gas Drainage

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Youxin Zhao ◽  
Qingjie Qi ◽  
Xinlei Jia
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Negative Pressure ◽  
Spontaneous Combustion ◽  
Orthogonal Test ◽  
Gas Drainage ◽  
Positive Linear Correlation ◽  
Drainage Hole ◽  
Spontaneous Combustion Of Coal ◽  
Fractured Coal

To accurately and reliably predict the time of spontaneous combustion of fractured coal around a borehole induced by gas drainage along the seam, this study performed an orthogonal test taking the No. 10 Coal Mine of Pingdingshan as the research object, in terms of the suction negative pressure and coal seam buried depth. COMSOL Multiphysics was used to model the orthogonal test results, and a multielement statistical analysis of four factors and their relationships with the spontaneous combustion of coal around the borehole and a single-factor analysis in line with the site conditions were performed on the modeling results through multiple regression. The results showed a nonlinear regression relationship between the sealing hole length, sealing hole depth, negative pressure, and coal seam depth and the spontaneous combustion of the coal around the gas drainage borehole; the prediction regression model is significant. Taking the field gas drainage in the No. 10 Coal Mine of Pingdingshan as an example, the relationship between the time of spontaneous combustion of gas drainage and the drainage pressure follows a power of two. When the drainage negative pressure is less than 45 kPa, the coal around the borehole is more likely to undergo spontaneous combustion with increasing pressure, and the sealing hole length has a positive linear correlation with the time of spontaneous combustion of the coal around the borehole. When the sealing hole length is 23 m, the time of spontaneous combustion of the coal around the gas drainage hole is >500 days, and the coal around the borehole does not easily undergo spontaneous combustion. When the sealing depth is 15 m, the time of spontaneous combustion of the coal around the gas drainage hole is 76 days, which is most likely to cause spontaneous combustion.

scholarly journals Overview of Research and use of Indicator Gases of Coal Spontaneous Combustion in China / Přehled Výzkumu a Využití Indikačních Plynů Samovznícení Uhlí V Číně

2014 ◽  
Vol 60 (1) ◽  
pp. 55-65 ◽  
Author(s):  
Xiyang Feng ◽  
Alois Adamus
Keyword(s):  
Spontaneous Combustion ◽  
Experimental Methods ◽  
Paper Briefly ◽  
Coal Spontaneous Combustion ◽  
Laboratory Equipment ◽  
Significant Development ◽  
The Sixties ◽  
Mine Fires ◽  
Spontaneous Combustion Of Coal ◽  
Program Characteristics

Abstract The beginnings of research and use of results in the area of indicator gas application for early detection of spontaneous combustion of coal in China comes from the sixties of the last century. The significant development occurred in the nineties, when the program “Characteristics of the adsorption of coal oxygen and its application in the prevention of mine fires” had been completed. The paper briefly describes an overview of the historical development, achievements, experimental methods, laboratory equipment, legislation, and the outlook for the use of indicator gases of coal spontaneous combustion in China

scholarly journals Research on a Gas Index Reflecting the Sorption Process on Carbon Materials in Coal Mines

2018 ◽  
Vol 10 (7) ◽  
pp. 2468 ◽  
Author(s):  
Karolina Wojtacha-Rychter ◽  
Adam Smoliński
Keyword(s):  
Carbon Materials ◽  
Spontaneous Combustion ◽  
Coal Mines ◽  
Sorption Process ◽  
Quantitative Relation ◽  
Gas Mixture ◽  
Coal Seams ◽  
Mine Fire ◽  
Sorption Column ◽  
Spontaneous Combustion Of Coal

Based on the concentration of gases such as propylene and ethylene in the atmosphere of a mine, it is possible to assess the development of a mine fire. With the increase of coal temperature, an increased emission of these gases has been observed. However, the experiment results presented in this paper prove that the use of propylene and ethylene for the prediction of the spontaneous combustion of coal have some limitations. It was found that during a flow of gas mixture through the sorption column, propylene and ethylene were sorbed on coal. This phenomenon manifests in smaller amounts of gases at the outlet of the sorption column. By comparing the concentration of ethylene to propylene at the inlet of the column, it was concluded that the ratio was usually below 3, whereas the range of the ratio at the end of the column was between 0.6–353. The value of gases ratio changed depending on the type of coal material in the column. The results of this experiment provide useful information that the quantitative relation between ethylene and propylene concentrations may indicate the occurrence of the sorption process on carbon materials in coal seams.

scholarly journals High-Temperature Mineral Phases Generated in Natural Clinkers by Spontaneous Combustion of Coal

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 213 ◽  
Author(s):  
Elisa Laita ◽  
Blanca Bauluz ◽  
Alfonso Yuste
Keyword(s):  
High Temperature ◽  
Spontaneous Combustion ◽  
Vitreous Phase ◽  
X Ray Diffraction ◽  
Ceramic Tiles ◽  
Mineral Phases ◽  
Fe Content ◽  
Spontaneous Combustion Of Coal ◽  
Compositional Variations ◽  
Refractory Ceramics

The aim of this study is to analyze natural clinkers (= calcined clays by coal combustion) from a lower Cretaceous coal outcrop in Ariño (Teruel, NE Spain) in order to describe mineral and textural transformations produced during the spontaneous combustion of coal. To achieve this aim, samples were analyzed using X-ray diffraction and optical and electron microscopy. Spontaneous combustion resulted in the melting of the surrounding clays, with the generation of an Al–Si-rich vitreous phase. Subsequently, high-temperature phases crystallized from this vitreous phase. These new minerals are interesting due to their similarity with those formed during ceramic processes, used in the manufacture of stoneware and ceramic tiles, as well as in refractory ceramics, and with natural events such as metamorphic and igneous processes. The studied natural clinkers are composed of vitreous phase mullite, hematite, hercynite, cristobalite, quartz, pyroxenes, cordierite, gypsum, pyrite, and calcium oxides. A trend from hematite to hercynite composition indicates compositional variations at sample scale, which evidence d-spacing differences in hercynite and may be related to the Al and Fe content in hercynite depending on its texture. The mullite shows higher Si/Al ratio (1.21) than the theoretical composition (0.35), indicating that this mullite is more Si-rich. Three pyroxene-type compositions (diopside-type, ferrosilite-type, and a Ca–Al-rich pyroxene) were found. Both the mullite and the pyroxenes are nonstoichiometric.

Study on the Relation between the Deep and the Spontaneous Combustion of Coal Seam

2014 ◽  
Vol 852 ◽  
pp. 821-825 ◽  
Author(s):  
Jian You Di ◽  
Er Xin Gao ◽  
Xian Long Sun ◽  
Chang Qing Sun ◽  
Yu Li Chen
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Laboratory Experiments ◽  
Spontaneous Combustion ◽  
Geothermal Gradient ◽  
Laboratory Analysis ◽  
Spontaneous Combustion Of Coal ◽  
Mine Depth ◽  
Relationship Of ◽  
The Relationship

Based on the data and laboratory analysis of Sun-Cun Coal Mine, the relationship between the geothermal gradient and the depth of mine in Suncun Coal Mine has been developed. According to this and the laboratory experiments, the relationship between spontaneous combustion period of coal seam and the depth of the mine has been obtained in this article. The results show that the law of coal seam spontaneous combustion period and the mine depth in accordance with the relationship of the gauss curve expression and when the coal mine depth is around 1000 m, the coal seam spontaneous combustion period shortened dramatically. This law should be pay more attention to.

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