Determination of the Spontaneous Combustion Hazardous Zone and Analysis of Influencing Factors in Bedding Boreholes of a Deep Coal Seam

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.

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Determination of capacity of powered supports for a longwall face of a thick coal seam

Mine Planning and Equipment Selection 2000 ◽

10.1201/9780203747124-48 ◽

2018 ◽

pp. 259-265

Author(s):

Samir Kumar Das

Keyword(s):

Coal Seam ◽

Longwall Face ◽

Thick Coal Seam

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Determination of conditions for spontaneous combustion of combustible dust deposits on equipment, in ventilation systems, and aspiration systems of buildings and structures

ПОЖАРОВЗРЫВОБЕЗОПАСНОСТЬ ◽

10.22227/pvb.2020.29.04.32-41 ◽

2020 ◽

Vol 29 (4) ◽

pp. 32-41

Author(s):

L. P. Vogman ◽

D. A. Korolchenko ◽

A. V. Khryukin

Keyword(s):

Spontaneous Combustion ◽

Growth Dynamics ◽

Operating Conditions ◽

Industrial Enterprises ◽

Process Characteristics ◽

Industrial Buildings ◽

Dust Deposits ◽

Production Facilities ◽

Ventilation Systems

Introduction. Determination of the scientifi cally substantiated frequency of cleaning the ducts of local exhausts of industrial buildings and structures is one of the tasks in the fi eld of fi re safety of industrial enterprises. The paper describes design methods, in particular, a method for determination of the induction period during spontaneous combustion of dust deposits in air ducts of ventilation systems and equipment, which can be used in solving problems focused on the development of preventive measures to ensure their fi re and explosion safety.Methods. In order to solve the problem set in this paper and compare the indicators obtained in the calculation and analytical part of the studies with the growth dynamics of deposits in real facilities, fi eld tests have been accomplished in the production facilities of the fl our mill of OJSC MK “Voronezhsky” and JSC Concern “Sozvezdiye”.Results and discussion. The timeframes for cleaning of deposits on ventilation (aspiration) equipment of buildings and structures cannot be universal for various industries and must take into account the dynamics of the growth of deposits depending on the specifi cs of combustible deposits, the workload of the production facilities of the protected object in a given period of time, and the operating conditions of the equipment. As a result of the experiments, it was found that the places of maximum accumulations of deposits are most often formed on the surfaces of joints and on the bends of pipelines of ventilation systems. The conditions of spontaneous combustion of combustible dust are studied by calculation and analytical method, depending on such process characteristics as the speed of the dust-air mixture fl ow in the duct, as well as the diameter of the duct’s cross section.Conclusions. The nomograms built on the basis of the studies performed can be used to determine the multiplicity of cleaning of combustible dusts of equipment and air ducts of industrial ventilation systems. The paper provides a calculation of the period of induction of spontaneous combustion of combustible dust deposits using the example of rye fl our with asymmetric heat transfer. Its signifi cance is due to the process of accumulation of deposits of combustible dust to a critical thickness in terms of spontaneous combustion conditions.

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

Inżynieria Mineralna ◽

10.29227/im-2021-02-06 ◽

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.

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

Shock and Vibration ◽

10.1155/2021/5533054 ◽

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.

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