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Title: A study of the spontaneous heating if Indian coals
Author: Mohalik, Niroj Kumar
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2013
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The Indian coal industry is currently facing a number of constraints (i .e. socio-economic, geotechnical and environmental issues) due to high demand of coal for industrial growth. In addition to the many potential geotechnical issues, the existence of extensive uncontrolled and concealed fires present a significant problem to the coal industry, the national economic growth and environment. The cause of many of these fires is the spontaneous heating of the coal seams (Zutshi et al., 2001) that create a significant problem to the productivity, safety and environmental impact of mining operations. The thesis presents the results of a systematic experimental study to determine the susceptibility of a number of Indian coal seams to spontaneous heating. A literature review revealed that the existing crossing point temperature method (CPT) assessment method is not reliable enough to be used to solely predict spontaneous heating. Therefore, there is a need to identify an additional robust and reliable technique to determine the susceptibility of coals to spontaneous heating, to assist in the classification of the coal seams with respect to their proneness to spontaneous heating. A comprehensive experimental study was conducted to analyse eleven coal samples collected from a variety of fiery and non-fiery coal seams within the Jharia coalfield (JCF) India. In the first part of the investigation, the basic coal characteristics, including a proximate, elemental, petrographic and mineral matter analysis were determined . The spontaneous heating susceptibility of all of the coal samples was studied using a number of methods, including: a morphology study of oxidised coal under microscopy, the use of the crossing point temperature method (Indian method), the use of the sponcomb rig at the University of Nottingham and the use of thermogravimetric analyses (TGA) of the coal samples. An analysis of the thermogravimetric results obtained for these coal samples at different heating rates resulted in the development of a spontaneous heating susceptibility index (SHSI). In addition, the activation energies were calculated from a kinetic study of the coal samples by employing the three different techniques attributed to Coats & Redfern (1963), Friedman (1964), and Chang (1994). Subsequently, a statistical correlation analysis was carried out to identify any links between the intrinsic properties of coal and the indices determined from the application of the different spontaneous heating susceptibility methods. It was observed that the proximate, elemental and petrographic analysis results correlated well with the spontaneous heating susceptibility results obtained from the sponcomb rig and TGA experiments. It was further concluded that the results of the mineral matter analyses do not exhibit a good correlation with any of the spontaneous heating susceptibility indices. The hierarchical clustering method was used to examine any links between the intrinsic coal properties and the result obtained from the application of each of the four susceptibility indices investigated. Each susceptibility index was subdivided into three levels, namely highly susceptible, moderately susceptible and poorly susceptible. A critical review of the literature reporting the classification of coal seams based on field observations, spontaneous heating susceptibility studies and hierarchical clustering theory concluded that any coal seam may be assigned to one of these three sub level classes by knowledge of the results obtained from the sponcomb rig and TGA experiments. An initial attempt was carried out to measure the greenhouse gas (GHG) emission fluxes in laboratory condition as well as from spontaneous heating of coal at one fire affected mine for the first time in India. Both initial laboratory and field study results concluded that there is no obvious relationship between the gas emissions experienced under both conditions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available