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TGA/DSC study to characterise and classify coal seams conforming to susceptibility towards spontaneous combustion

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International Journal of Mining Science and Technology 2022年第1期32卷 75-88页

作者： Niroj Kumar Mohalik Somu Mandal Santosh Kumar Ray Asfar Mobin Khan Debashish Mishra Jai Krishna Pandey CSIR-Central Institute of Mining and Fuel Research(CIMFR) Dhanbad 826015India Academy of Scientific and Innovative Research(AcSIR) Ghaziabad 201002India

Thermogravimetric analysis/differential scanning calorimeter(TGA/DSC)technique along with basic coal characteristics study is carried out for eighty coal samples of Indian coalfields,to determine spontaneous combustion propensity behaviour of *** study of coal samples indicates that there is an increase in the mass of coal samples in the temperature range 150-350℃,which may be due to oxygen adsorption and *** correlation and principal component analysis states that the component of proximate analysis(M_(ad),VM_(d),FR,and VR)have an acceptable correlation with the TGA experiments results i.e.,Tgsh and *** fixed nonlinear regression analysis shows that thermogravimetry(TG)experiment results Tgign may be the best index to categorise/classify the coal as per their susceptibility towards spontaneous *** authors proposed four groups of classification as per their propensity towards spontaneous combustion depending upon the moisture(M_(ad)),volatile matter(VM_(d)),and TG ignition temperature from differential thermogravimetric(DTG)curve(Tgign)using hierarchal clustering *** coal samples of different seams from Indian coalfield may be classified into four different clusters,*** highly/extremely susceptible(Tgign320℃).The field observations and TGA/DSC experiment results with the following statistical analysis substantiate a similar assessment.

关键词： Coal TGA/DSC spontaneous combustion TG ignition

Computer controlled measurement of spontaneous combustion in coal stockpiles of the Western Lignite Corporation, Turkey

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Journal of University of Science and Technology Beijing 2006年第2期13卷 97-101页

作者： A. Hadi Ozdeniz Cem Sensogut Mining Engineering Department Selcuk University 42079 Konya Turkey Mining Engineering Department Dumlupinar University 43100 Kutahya Turkey

The spontaneous combustion event in coal stockpiles is inevitable when appropriate environmental conditions are available. The objective of a computerized measurement system is to measure temperature changes existing in a coal stockpile. In order to achieve this intention, the electrical signal conversion of temperatures sensed by 20 temperature sensors placed in certain points inside the coal stockpile, the transfer of these electrical signals into computer media by using analogue-digital conversion unit after applying necessary filterization and upgrading processes and the record of these information into a database in particular time intervals are provided. Afterwards, the diagrams of these time-temperature data are plotted. With the help of these graphs, the competent company will be able to examine the behavior of coal stockpiles in terms of spontaneous combustion and take necessary precautions against self-combustion beforehand.

关键词： spontaneous combustion coal stockpile Western Lignite Corporation resistance temperature detector

Experiment study of optimization on prediction index gases of coal spontaneous combustion

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Journal of Central South University 2016年第9期23卷 2321-2328页

作者： NIU Hui-yong School of Energy and Safety Engineering Hunan University of Science and Technology Xiangtan 411201 China Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines (Hunan University of Science and Technology) Xiangtan 411201 China

The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory determination were initialized for the value which was defined as "K". The ratio of each index gas and value of "K", and the ratio of combination index gases and value of "K", were analyzed simultaneously. The research results show that for this coal mine, if there is carbon monoxide in the gas sample, the phenomenon of oxidation and temperature rising for coal exists in this mine; if there is C_2H_4 in the gas sample, the temperature of coal perhaps exceeds 130 °C. If the coal temperature is between 35 °C and 130 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(CO)/K mainly; if the temperature of coal is between 130 °C and 300 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(C_2H_6)/Φ(C_2H_2) and Φ(C_2H_6)/K. The research results provide experimental basis for the prediction of coal spontaneous combustion in Anyuan coal mine, and have better guidance on safe production of this coal mine.

关键词： coal spontaneous combustion index gases prediction initialization

Analysis of spontaneous combustion liability indices and coal recording standards/basis

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International Journal of Mining Science and Technology 2020年第5期30卷 723-736页

作者： A.R.Gbadamosi M.Onifade B.Genc S.Rupprecht School of Mining Metallurgy and Chemical EngineeringUniversity of JohannesburgSouth Africa Department for Management of Science and Technology Development Ton Duc Thang UniversityHo Chi Minh CityViet Nam Faculty of Applied Sciences Ton Duc Thang UniversityHo Chi Minh CityViet Nam School of Mining Engineering University of the WitwatersrandJohannesburgSouth Africa

The characterization of the physical and chemical properties of coal on a standard provides an understanding of its characteristics towards spontaneous *** trend of linear relationships between coal recording standards(%air-dried(ad),%dry(db)and%dry ash free(daf)basis)of 30 selected coal samples from the Witbank coalfields and spontaneous combustion liability indices were *** spontaneous combustion liability indices of these samples were evaluated by crossing point temperature(XPT),Stage II Slope,FCC(Feng,Chakravorty,Cochrane)and the Wits-Ehac tests,while the coal properties were determined from the proximate and ultimate *** results obtained from these coal properties were related to different liability indices to develop trends of linear relationships using regression *** ad basis indicated higher correlation coefficients than the db and daf basis for the XPT and FCC index,while the daf showed higher correlation coefficients than the ad and db basis for the Wits-Ehac *** was found that the trend of linear relationships of these coal properties differs from one liability index to the *** XPTs showed a better trend followed by the Stage II Slope on the coal properties among the spontaneous combustion liability indices evaluated.

关键词： Coal basis Correlation analysis Liability indices spontaneous combustion

A new apparatus to establish the spontaneous combustion propensity of coals and coal-shales

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International Journal of Mining Science and Technology 2018年第4期28卷 643-649页

作者： M.Onifade B.Genc A.Carpede School of Mining Engineering University of the Witwatersrand

Coal and coal-shale both tend to undergo spontaneous combustion under favourable atmospheric conditions. The Wits-Ehac index has been developed in South Africa since the late 1980's to test the spontaneous combustion liability of coal. However, in some cases, the Wits-Ehac index fails to produce tangible results when testing coal-shales. To overcome this problem, a new apparatus has been developed to test carbonaceous materials such as coal and coal-shale under chemical reactions with oxygen and an index has been obtained. This index is called the Wits-CT index. The equipment emulates the influence of oxygen adsorption on carbonaceous material for a period of 24 h without a heating *** Wits-CT index uses the total carbon content of the sample and the temperature variations obtained from the samples during reaction with oxygen to predict the spontaneous combustion liability. Eighteen samples have been analyzed using both indices and the results are in-line. It was found that coals and coal-shales with higher values of the Wits-CT index are more liable to spontaneous *** research on different coal-shales is underway in order to establish an extensive database for coal and coal-shales, together with known incidences of self-heating.

关键词： Coal Coal-shale spontaneous combustion Wits-Ehac index Wits-CT index

Locating method of fire source for spontaneous combustion of sulfide ores

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Journal of Central South University 2011年第4期18卷 1034-1040页

作者：刘辉吴超石英 College of Quality and Safety Engineering China Jiliang University School of Resources and Safety Engineering Central South University

in order to achieve a more efficient way to accurately detect the position of the fire source of spontaneous combustion underground mine, a simple fire source locating method, based on infrared scanning system which can determine the point where the highest temperature on the surface of igniting ores occurs, was proposed. First, the differential equations that describe heat flow in ore body were presented and the relationship between the surface temperature distribution and the depth and intensity of inner fire source was established with a relatively simple heat transfer model. With the solution of equation, the expression of the relationship between the surface temperature distribution and the inner fire source was deduced and the mathematical-physical model of heat transfer process was set up. Then, with the model, visualization of fire source on the basis of MATLAB simulation platform was realized. The results show that： 1） within 10 m, when the detecting depth is less than 2 m, the temperature perturbation on ores surface can change rapidly, and then slowly; after 4 m, in contrast, it changes very little, and is even close to zero at 10 m; 2） When it is close to self-ignition duration and the detective depths are 2, 5 and 10 m, respectively, the maximum temperature differences are correspondingly 0.5, 0.04 and 0.005 ℃ in the scope of 1 m×1 m; under the same condition, the maximum temperature differences are 1.391, 0.136 and 0.018 ℃, respectively, in the scope of 2 m×2 m. Therefore, this system can be used to measure the temperature differences on the surface of ore body and determine the highest temperature point directly. Also, it is possible to determine the depth of fire source and its intensity by locating method of fire source indirectly.

关键词： sulfide ores spontaneous combustion location of fire source detection

Numerical Simulation Study of Goaf Methane Drainage and spontaneous combustion Coupling

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Journal of China University of Mining and Technology 2007年第4期17卷 503-507页

作者： LI Zong-xiang LU Zhong-liang WU Qiang ZHANG Ai-ran College of Vocational Liaoning Technical University Fuxin Liaoning 123000 China School of Safety Science and Engineering Henan Polytechnic University Jiaozuo Henan 454003 China Heilongjiang Institute of Science and Technology Harbin Heilongjiang 123000 China School of Energy and Safety Engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

In order to study the coupling problem between methane drainage and spontaneous combustion of residual coal in the collapsed zone after mining ignitable coal seams with high methane,we have analyzed the effects of differ-ent methane drainage modes on spontaneous combustion of residual coal through numerical simulation. The results show that deep and large flux methane drainage modes increases the air leakage from work faces to the goaf and formed new spontaneous combustion zones induced by drainage near vents,which increases the risk of self-ignition of coal—reducing the self-ignition period and enlarging the scale of self-ignition. The spontaneous upstream combustion oxidation of the main fire zone can be suppressed when both drainage and nitrogen injection were adopted. Our research results provide an effective technical measure and theoretical basis to determine the best methane drainage scheme and drainage parameters.

关键词： goal methane drainage spontaneous combustion multiphase gas flow field finite element

Detection of Coal Mine spontaneous combustion by Fuzzy Inference System

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Journal of China University of Mining and Technology 2006年第3期16卷 258-260,265页

作者： SUN Ji-ping SONG Shu MA Feng-ying ZHANG Ya-li Institute of Information Engineering China University of Mining ＆ Technology Beijing 100083 China College of Electronic Information and Control Engineering Shandong Institute of Light Industry Jinan Shandong 250100 China Department of Security and Prevention Chinese People＇s Public Security University Beijing 100038 China

The spontaneous combustion is a smoldering process and characterized by a slow burning speed and a long duration. Therefore, it is a hazard to coal mines. Early detection of coal mine spontaneous combustion is quite difficult because of the complexity of different coal mines. And the traditional threshold discriminance is not suitable for spontaneous combustion detection due to the uncertainty of coalmine combustion. Restrictions of the single detection method will also affect the detection precision in the early time of spontaneous combustion. Although multiple detection methods can be adopted as a complementarity to improve the accuracy of detection, the synthesized method will in- crease the complicacy of criterion, making it difficult to estimate the combustion. To solve this problem, a fuzzy inference system based on CRI （Compositional Rule of Inference） and fuzzy reasoning method FITA （First Infer Then Aggregate） are presented. And the neural network is also developed to realize the fuzzy inference system. Finally, the effectiveness of the inference system is demonstrated bv means of an experiment.

关键词： spontaneous combustion fuzzy inference system CRI FITA neural network

Comparative analysis of coal and coal-shale intrinsic factors affecting spontaneous combustion

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International Journal of Coal Science & Technology 2018年第3期5卷 282-294页

作者： M. Onifade B. Genc The School of Mining Engineering University of the Witwatersrand P.O. WITS Johannesburg 2050 South Africa

Coal and coal-shales tend to undergo spontaneous combustion under favourable atmospheric conditions. spontaneous combustion liability index and intrinsic properties of coals and coal-shales varies between （above and below） coal seams. The spontaneous combustion liability index （obtained from the Wits-Ehac Index） and intrinsic properties （obtained from proximate, ultimate, and petrographic analysis） of fourteen samples representative of in situ coal （bituminous） and fourteen coal-shales obtained in Witbank coalfield, South Africa were experimentally studied. Comparative analysis of the relationships between the spontaneous combustion liability index and intrinsic properties of coals and coalshales were established to evaluate their effects on self-heating potential. The intrinsic properties show linear relationship with spontaneous combustion liability and therefore, identifies the factors affecting spontaneous combustion of these materials. The influence of coal-shales intrinsic properties towards spontaneous combustion liability shows higher correlation coefficients than the coals. Both coals and coal-shales show inertinite maceral as major constituents than the vitrinite and liptinite macerals, hence the reactivity of inertinite macerals may show greater influence on spontaneous combustion liability. A definite positive or negative trends exists between the intrinsic properties and spontaneous combustion liability index. This research is part of a larger project which is considering the influence of intrinsic properties of coals and coal-shales on spontaneous combustion liability.

关键词： Coal-shales spontaneous combustion Liability index Statistical analysis and correlation coefficient