Spontaneous combustion of coals and coal-shales

Onifade, Moshood; Genc, Bekir

doi:10.1016/j.ijmst.2018.05.013

Cited by 126 publications

(55 citation statements)

References 55 publications

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“…It is known that coal, roof shales and spoil heaps may become self-heated and liberate heat naturally under favourable weather conditions. Sedimentary rocks such as coal and coal-shale, consist of certain amounts of organic matter (macerals) and inorganic materials (mainly crystalline) causing them to likely undergo self-heating leading to spontaneous combustion (Onifade and Genc 2018d). Reactive sedimentary materials have pore spaces embedded in the solid together with the occurrence of a carbon-rich element (Dullien 1979 air, increases its surface area, thus making the organic particles reactive as it permits oxidation to occur (Dullien 1979).…”

Section: Introductionmentioning

confidence: 99%

“…Spontaneous combustion of coals and coal-shales is an important phenomenon that requires indepth investigation. Studies of self-heating of coal-shales in selected bands of coal seams and highwalls are limited Onifade and Genc 2018d). Limited information is available to investigate and predict the spontaneous combustion liability of coal-shales in relation to coals.…”

Section: Introductionmentioning

confidence: 99%

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Modelling spontaneous combustion liability of carbonaceous materials

Onifade

Genc

2018

Int J Coal Sci Technol

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This paper presents predictive models to determine spontaneous combustion liability of carbonaceous materials (coals and coal-shales) using statistical analysis. The intrinsic properties and spontaneous combustion liability index were determined by testing 14 coals and 14 coal-shales from Witbank coalfields, South Africa. The relationship between these intrinsic properties (obtained from proximate, ultimate and petrographic analysis) and spontaneous combustion liability indices (the Wits-Ehac Index and Wits-CT Index) were established. The influence of the intrinsic properties of coal-shales in relation to coal properties affecting spontaneous combustion has been established using a statistical method. The linear regression analysis indicates better linear relationships between some of the selected intrinsic properties and spontaneous combustion liability index and thus, identifies the major intrinsic factors affecting their liability toward spontaneous combustion. It was found that a definite positive or negative correlation coefficient exists between the intrinsic factors and spontaneous combustion liability. A set of models to predict the spontaneous combustion liability was derived. The best significant correlation along with the most appropriate model as indicated by R-squared values, the coefficient of correlations and standard error was used to predict the incident of spontaneous combustion.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modelling spontaneous combustion liability of carbonaceous materials

Onifade

Genc

2018

Int J Coal Sci Technol

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“…2 and 4 to spontaneous combustion. It is commonly known that some of the minerals within coal, for example pyrite may accelerate the self-heating process [38][39][40]. The exothermic reaction of pyrite oxidation due to the interaction of water and oxygen produces heat, which under favorable conditions leads to coal self-heating.…”

Section: Ash and Sulfur Contentmentioning

confidence: 99%

Profile of CO2, CO, and H2 Emissions from Thermal Oxidation of Polish Coals

Wojtacha‐Rychter

Smoliński

2020

Materials

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The self-heating phenomenon of coal leads to work safety hazards in underground mining. The quantitative analysis of gaseous products in mine atmosphere constitutes one of the detection methods of advanced coal heating. The article presents the results of tests on CO, CO 2 , and H 2 emissions during simulated heating of coal in the temperature range of 323-523 K. The oxidation of 15 Polish coals of various carbon contents was performed using a flow reactor technique. A chromatography method was applied to measure the changes of oxidation products concentrations with the increase of temperature. It has been determined that all the tested gases were generated at the initial temperature. The collected data indicated that CO 2 was a major oxidation product in the entire temperature range, while the amounts of H 2 produced did not exceed 0.49% volume. At the temperature of 323 K, the ratio of CO 2 /CO was in the range of 10-23 but along with the temperature increase the ratio range narrowed to 3-4. In this paper, a comparison of the physical-chemical properties of the tested coals and the emissions profile of the gases using, among others, the hierarchical clustering analysis showed that samples with higher oxygen, sulfur, and inertinite content as well as lower ash and carbon content formed larger amounts of fire gases.

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“…Granular coal is reactive and undergoes spontaneous combustion rapidly but a combination of different coal particle sizes is highly liable to spontaneous combustion (Kucuk et al 2003). The extent of self-heating is based on a complex relationship between various intrinsic and extrinsic factors of coal (Onifade and Genc 2018c;Uludag 2007). Bhat and Agarwal (1996) indicated that the coal particle size may influence heat loss via convection and the heat produced by the mass transfer coefficient, which controls the degree of moisture condensation.…”

Section: Seam Factorsmentioning

confidence: 99%

Spontaneous combustion liability of coal and coal-shale: a review of prediction methods

Onifade

Genc

2019

Int J Coal Sci Technol

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This study presents a review of the various methods to predict the spontaneous combustion liability of coal and coal-shale. The relative propensity of coal to undergo self-heating can be established by different methods. These methods are well established in their usage, but the fact that no particular test method has become a standard to predict the spontaneous combustion liability indicates that doubt still exists as to the validity of all of them. The underlying principle of all the tests is that the more readily the coal undergoes exothermic oxidation, the more liable it is to self-heat. Comprehensive studies that centres on the international position on research being conducted by academics, different research institutes and industries on spontaneous combustion of coal and coal mine fires were evaluated. Relationships between the geochemical analysis (proximate and ultimate analysis, forms of sulphur, petrographic properties, X-ray diffraction and X-ray fluorescence) and spontaneous combustion testing methods (numerical and experimental approaches) used to predict the spontaneous combustion liability of coal were reviewed. The combination of these tests provides a better understanding of the mechanism that controls the spontaneous combustion phenomena. However, irrespective of the extensive studies that have been conducted over time, spontaneous combustion is still a major problem in the coal value chain.

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Spontaneous combustion of coals and coal-shales

Cited by 126 publications

References 55 publications

Modelling spontaneous combustion liability of carbonaceous materials

Modelling spontaneous combustion liability of carbonaceous materials

Profile of CO2, CO, and H2 Emissions from Thermal Oxidation of Polish Coals

Spontaneous combustion liability of coal and coal-shale: a review of prediction methods

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