1. Fuzzy c-means clustering approach for classification of Indian coal seams with respect to their spontaneous combustion susceptibility
模糊c均值聚类算法在印度煤自燃易感性分类中的应用
Fuel Processing Technology, Volume 104, December 2012, Pages 115-120
H.B. Sahu, S.S. Mahapatra, D.C. Panigrahi
Abstract: Mine fire due to spontaneous combustion in coal mines is a global concern. This leads to serious environmental and safety hazards and considerable economic losses. Therefore, it is essential to assess and classify the coal seams with respect to their proneness to spontaneous combustion to plan the production, storage and transportation capabilities in mines. This paper presents a fuzzy c-mean approach for classification of coal seams based on their proneness to spontaneous combustion. This produces sets of non-exclusive clusters that allow coal samples to have memberships in multiple clusters, rather than only in exclusive partitiobns, as generated by hierarchical and k means clustering. In this research work, fifty one coal samples of varying ranks belonging to both high and low susceptibility to spontaneous combustion have been collected from all the major coalfields of India. Using moisture, volatile matter, ash content and crossing point temperature of the coal samples as the parameters, the proposed algorithm has been applied to classify the coal seams into three different categories. This classification will be useful for the planners and field engineers for taking ameliorative measures in advance for preventing the occurrence of mine fires.
2. A discrete particle swarm optimization approach for classification of Indian coal seams with respect to their spontaneous combustion susceptibility
离散粒子群优化算法在印度煤自燃易感性分类中的应用
Fuel Processing Technology, Volume 92, Issue 3, March 2011, Pages 479-485
H.B. Sahu, S.S. Mahapatra, K. Sirikasemsuk, D.C. Panigrahi
Abstract: Mine fires due to spontaneous combustion in coal mines is a global concern. This leads to serious environmental and safety hazards and considerable economic losses. Therefore it is essential to assess and classify the coal seams with respect to their proneness to spontaneous combustion to plan the production, storage and transportation capabilities in mines. This paper presents the formulation of clustering problem into a linear assignment model and the application of a discrete particle swarm optimization approach for the classification of coal seams based on their proneness to spontaneous combustion. In this research work, twenty nine coal samples of varying ranks belonging to both high and low susceptibilities to spontaneous combustion have been collected from all the major coalfields of India. Using moisture, volatile matter, and ash content and crossing point temperature of the coal samples as the parameters, the proposed algorithm has been applied to classify the coal seams into three different categories. This classification will be useful for the planners and field engineers for taking ameliorative measures in advance for preventing the occurrence of mine fires.
3. Aqueous three-phase foam supported by fly ash for coal spontaneous combustion prevention and control
粉煤灰、含水三相泡沫在煤自燃预防中的应用
Advanced Powder Technology, Volume 25, Issue 5, September 2014, Pages 1527-1533
Botao Qin, Yi Lu, Yong Li, Deming Wang
Abstract: This work deals with the preparation and characterization of fly ash (FA) supported aqueous three-phase foams containing N2 for coal spontaneous combustion prevention and control. Uniform and dense three-phase foams featuring FA contents between 20 wt.% and 33 wt.% are prepared in batch mode using a home-made foam generating column with an internal Venturi tube. The effect of FA on the foamability, static and dynamic stability of the three-phase foams is discussed. Compared with two phase foams, the FA supported three-phase foams manifest higher static and dynamic stability, which increases with the FA content. Base on the excellent static and dynamic stability, a structure model to attach FA particles at the N2–water interfaces of the three-phase foams was proposed to elucidate the observed behaviors. The as prepared FA supported three-phase foams, exhibiting excellent coal fire extinguishing characteristic, can be used as a promising fire extinguishing material, especially for preventing the large coal area spontaneous combustion or extinguishing fire in high and unknown locations in goaf.
4. Spontaneous Heating and Fire in Coal Mines
煤自燃发火机理研究
Procedia Engineering, Volume 62, 2013, Pages 78-90
Ran Vijay Kumar Singh
Abstract: Spontaneous heating and fire in coal mines is a major problem worldwide and has been a great concern both for the industry and researchers in this field. Majority of fires existing today in different coalfields are mainly due to spontaneous combustion of coal. The auto oxidation of coal ultimately leads to spontaneous combustion which is the major root cause for the disastrous of coal mine in leading and coal producing countries like USA, China, Australia, India and Germany. It is a slow process and the heat evolved is carried away by air. This process of self-heating of coal or other carbonaceous material resulting eventually in its ignition is termed as “spontaneous heating” or “auto oxidation”. Coal can interact with oxygen in the air at ambient temperature liberating heat. If the heat is allowed to accumulate the interaction rate increases and may ultimately lead to fires – known as spontaneous fires.
The exact mechanism of the reaction of oxygen with coal is not completely understood as the chemical nature of coal is not yet fully established. But most of the workers agree that the reaction of oxygen with coal is a surface phenomenon and proceeds through a loosely bound coal-oxygen-water complex with subsequent steps being breakdown of the complex to simpler molecules such as CO, CO2 and H2O etc. Most popular hypothesis is that the overall reaction proceeds through a chain mechanism with moisture facilitating the formation of free radicals that act as chain carrier. Due to fire in coal mines, hues quantity of noxious gases liberated in the atmosphere which damage the ecological balance of nature. There are various technologies available in different parts of world to prevent and control spontaneous heating. Out of these technologies, chemical inhibitors play a vital role to control and combat fires. The main objective of this paper is to elaborate the causes, mechanism of spontaneous heating and technological advancement mainly development of chemical inhibitors for controlling and combating fire in coal mines.
5. Experimental research on inorganic solidified foam for sealing air leakage in coal mines
无机固化泡沫在矿井填充防漏应用中的实验研究
International Journal of Mining Science and Technology, Volume 23, Issue 1, January 2013, Pages 151-155
Bo tao Qin, Yi Lu
Abstract: In order to efficiently seal air leakages and control spontaneous combustion of coal, solidified foam was developed by adding a certain compound additive to fly coal ash and cement as the main materials. It was prepared basing on the foaming characteristic through physical and mechanical system. We studied the effects of the different types of foaming agents, the mass ratio of cement to fly ash, and the mass ratio of solid to water and content of cellulose on the performance of solidified foam. The results show that when adding the composite protein, surfactant and cellulose foaming agents. The cement-fly ash ratio of 0.75:1, the water solid ratio as large as 2:1, and the solidified foam with high properties and density of only 516 kg/m3 and compressive strength of up to 12.68 MPa were prepared. But the initial setting time, identity and compressive strength may be changed by varying the water solid ratio and/or the additives. We theoretically analyzed the influence mechanism of foam density, compressive strength and water solid ratio. The solidified foam is especially suitable for sealing surface leakage channels and filling the goaf with a wide application prospects.
6. The shortest period of coal spontaneous combustion on the basis of oxidative heat release intensity
基于氧化放热强度预测煤最短自燃发火期
International Journal of Mining Science and Technology, Volume 24, Issue 1, January 2014, Pages 99-103
Yongliang Yang, Zenghua Li, Shisong Hou, Fanjun Gu, Siyuan Gao, Yibo Tang
Abstract: It’s necessary to forecast the shortest spontaneous combustion period for preventing and controlling the coal spontaneous combustion. During the experimental process, a calculating model of the SSCP is established on the basis of the oxidative heat release intensity and thermal capacity at different temperatures. According to the basic parameters of spontaneous combustion, heat of water evaporation and gas desorption, the SSCPs of different coals are further predicted. Finally, this study analyzed the relationships of the SSCP and the judging indexes of the self-ignite tendency. The result shows that the SSCP non-linearly increases with the decrease of dynamic oxygen adsorption and increase of activation energy. Compared with the practical fire situation of mine, this reliable method can meet the actual requirement of mine production.
7. Investigation of the Role of Fire Retardants in Preventing Spontaneous Heating of Coal and Controlling Coal Mine Fires
阻燃剂在煤自燃防治中的作用研究
Pandey, J. (Mine Fire Division, Central Institute of Mining and Fuel Research, Dhanbad, India); Mohalik, N.K.; Mishra, R.K.; Khalkho, A.; Kumar, D.; Singh, V.K. Source: Fire Technology, p 1-19, 2012
Abstract: Mine fire is a major problem for the Indian coal mining industry and exists since beginning of the mining. A huge amount of the prime coking coal reserves of different coalfields are blocked due to existence of fire and thus cannot be extracted without extinguishing it. Many approaches have been attempted in this direction to minimize this socio-technological problem. Use of chemical retardants to inhibit smouldering combustion phenomenon is an important method, which can be adopted to prevent or delay its occurrences. In this situation, it may sometimes be necessary to use fire retardants for reducing the intensity of fire so that the coal production will not be hampered. This paper presents the impact of chemical additives on coal oxidation process, studied from the mechanistic perspective aiming to search effective retardant materials to prevent and control coal self-heating phenomenon. A numbers of chemicals and combinations along with coal, which are moderately prone to smouldering combustion, were studied to determine its efficacy to prevent and combat it. In the process CPT, IPT and DSC study of coal samples and chemicals were observed. Based on the results, suitable retardants were selected and mixed with coal samples. The mixtures were further analysed for above properties. Finally, the best suitable combination of inhibitors were determined and applied in the field, which gave desired results. © 2012 Springer Science+Business Media New York.
8. Technology research on applying the flue gas of mine mouth power plant to fire prevention and extinguishing in goaf
基于煤矿坑口电厂烟气研究采空区防灭火技术
Yin, Bin1, 2 ; Han, Guang1, 2; Jia, Bao Shan1, 2; Ai, Xing1, 3; Pi, Zi Kun1, 2
Source: Advanced Materials Research, v 1010-1012, p 1502-1506, 2014, Environmental Protection and Resources Exploitation II; ISSN: 10226680, E-ISSN: 16628985; ISBN-13: 9783038352099; DOI: 10.4028/www.scientific.net/AMR.1010-1012.1502; Conference: 2nd International Conference on Advances in Energy and Environmental Science, ICAEES 2014, June 21, 2014 - June 22, 2014; Publisher: Trans Tech Publications Ltd
Abstract: Based on the concept of cleaner production, the feasibility of application of the flue gas in mine mouth power to fire prevention and extinguishing in goaf was numerically studied by taking the mechanized caving mining face 11-214 of Caocun coal mine as the example. The heterogeneity porosity and multi-component gas transport equations were introduced into the mathematical model. The calculated results showed that the area of "spontaneous combustion zone" turn small obviously in goaf and the maximum width of "spontaneous combustion zone" in goaf decreased from 78m to 9.5m after injecting the flue gas. At the same time, the sink terms of oxygen consumption was formed in the port of gas injection. The migration law of flue gas showed that the numerical calculation of goaf should select the different computation model based on the judgment basis of Reynolds number. Through the continuous monitoring of the migration of flue gas at different locations in goaf, the reasonable parameters of flue gas injection was obtained for high efficient fire prevention.
9. Numerical simulation and backfilling materials research on coal spontaneous combustion of thick seam large-scale top-caving region in resources conformity coal mine
基于数值模拟和回填材料的厚煤层大型综放开采区煤自燃资源整合系统研究
Tan, Bo1 ; Jiang, Yuangang1 ; He, Chaonan2 ; Chang, Jing2 ; Luo, Yaqi2
Source: Advanced Materials Research, v 524-527, p 317-320, 2012, Natural Resources and Sustainable Development II; ISSN: 10226680; ISBN-13: 9783037854174; DOI: 10.4028/www.scientific.net/AMR.524-527.317; Conference: 1st International Conference on Energy and Environmental Protection, ICEEP 2012, June 23, 2012 - June 24, 2012; Publisher: Trans Tech Publications
Abstract: This paper aimed at fire control in thick seam large-scale top-carving region. On the basis of coal and oxygen compounding theory, theoretical analysis, numerical simulation and experiment are combined, and a coal spontaneous combustion process model is built according to fluid mechanics and control theory. By studying and testing on top-carving coal spontaneous combustion process, conclusion is drawn that spontaneous combustion area is the largest in partly-closed region, followed by unclosed region. A totally closed baffle leads to the smallest spontaneous combustion area and the smallest possibility of fire. With local materials in a certain condition, new, cheap backfilling materials are developed. Thus provide theoretical basis for study on the forecasting and prevention of thick seam large-scale top-carving coal spontaneous combustion.
10. Prevention, control and/or extinguishment of coal seam fires using cellular grout
多孔灌浆技术在煤层防灭火中的应用
Colaizzi, Gary J.1
Source: International Journal of Coal Geology, v 59, n 1-2, p 75-81, July 12, 2004; ISSN: 01665162; DOI: 10.1016/j.coal.2003.11.004; Publisher: Elsevier
Abstract: Coal fires are difficult and persistent problems throughout the world wherever coal is at or near the surface. Coal fires can be associated with mining activities including underground and surface mine operations, coal stockpiles and coal waste piles, and they can also occur in unmined areas along coal seam outcrops. Environmental safety and health hazards are posed by coal fires in the form of ground surface subsidence, air pollution, forest and brush fires, and destruction of property and surface improvements, in addition to the potential massive loss of energy resources. While many causes exist, the most common source of coal fire ignition is spontaneous combustion as weathered, or broken/pulverized coal oxidizes and the temperature rises to the ignition point. This process can occur before any mining in the case of outcrop fires, or anytime during and after the mining cycle. The magnitude of coal fire problems varies worldwide depending on reserves available, extent of mining, population, political/economic situations, and a host of other influencing factors. Mining and environmental regulations imposed in the United States have heightened awareness regarding coal fire problems and resulted in efforts to control the most problematic existing fires and extinguish small fires before they escalate. Coal fires in other major coal-bearing countries, such as China and India, pose a significantly greater problem in terms of worldwide impact. Figures for China vary dramatically but estimates indicate that as much as 100-200 million tons of coal reserves are consumed annually as a result of coal fires. Similar estimates for the Jharia Coal Field in India indicate that about 40 million tons of coal reserves were burned during the 1990s. These data point to a significant source of global pollution, in addition to substantial economic losses.] Goodson & Associates, Inc. (G & AI), a Lakewood, CO engineering firm, has developed a technology utilizing cellular (foam containing) grout to mitigate coal fires from the perspectives of prevention, control and extinguishment. The variable combination of portland cement, waste fly ash, aggregates and special foams create a highly flowable, high-heat resistant grout that is used to simultaneously address each of the three necessary fire elements: fuel, oxygen and heat. Coal fire prevention can be achieved by spraying the material on the exposed surface of coal seams following completion of strip mining. Control is enabled by grout injection into cracks, vents and cut-off trenches to stall or prevent continued growth. Extinguishment can be accomplished by grout injection directly into the fire zone, air intakes and exhausts. The benefits of using this technology are numerous. Cellular grout injection is safer at lower cost than conventional techniques such as complete excavation, while causing less environmental disruption and providing for quicker applications. The use of large quantities of fly ash in the process is economically and environmentally sound, by providing for disposal of a waste material while addressing the worldwide problem of coal fires.
11. Experimental studies on preparation of multi-phase foamed gel for preventing spontaneous combustion of coal
防治煤炭自燃的多相凝胶泡沫制备实验研究
Qin, Botao1; Zhang, Leilin1
Source: Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology), v 44, n 11, p 4652-4657, November 2013; Language: Chinese; ISSN: 16727207; Publisher: Central South University of Technology
Abstract: In order to prevent the spontaneous combustion of coal efficaciously, a new compound material of multi-phase foamed gel, which is based on three-phase foam, which is composed of foaming agent, thickener, fly ash and nitrogen and formed by physical and mechanical stirrings, was proposed. It makes use of the all-around capability of gel and three-phase foam to prevent mine fire. The effects of the mass fraction of foaming agent and slurry, the quantitative ratio of polymers and content on foam properties were studied. In addition, the effects of solution pH and solid particle on the properties of multi-phase foamed gel were also studied. The results show that the properties of multi-phase foamed gel are the best when the mass fraction of foaming agent, polymers and slurry are 4‰, 6‰(the mass ratio is 1:1) and 16.66%(water cement mass ratio is 5:1).
12. Development of a new material for mine fire control
新型防灭火材料技术进展
Zhang, Leilin1, 2; Qin, Botao1, 2
Source: Combustion Science and Technology, v 186, n 7, p 928-942, July 3, 2014; ISSN: 00102202, E-ISSN: 1563521X; DOI: 10.1080/00102202.2014.890600; Publisher: Taylor and Francis Inc.
Abstract: In order to prevent the spontaneous combustion of coal efficaciously, a new kind of compound material of multiphase foamed gel is obtained, which is composed of fly ash, foaming agent, thickener, crosslinker, and nitrogen and formed by physical and mechanical stirring. It makes use of the all-around capability of gel, foam, grouting, and inhibitor to prevent mine fires. The formation and crosslinking mechanism of multiphase foamed gel were analyzed in theory, and the effects of the mass fraction of foaming agent and slurry, the quantitative ratio of polymers, and concentration and solid particle on foam properties were carried out. Meanwhile, the resistant property and inhibition characteristic of multiphase foamed gel were studied experimentally and theoretically. The multiphase foamed gel provides a new technical method to prevent the coal spontaneous combustion and thereby it has a vast potential and development prospect.
