Abstract
Coal spontaneous combustion is one of the main potential hazards in the process of mining. To study the spatial and temporal variations of higher-temperature area and indicator gases, an adiabatic oxidation testing system was developed to simulate the whole process of coal spontaneous combustion. The experimental results show that the entire process of coal spontaneous combustion could be divided into three stages: slow-oxidation, accelerated-oxidation and combustion stages. In the slow-oxidation stage, the higher-temperature area shifted slowly from the bottom to the top and then stayed at the top until accelerated-oxidation stage was reached; [Formula: see text] and [Formula: see text] concentration remained more or less constant as well as the oxygen concentration. In accelerated-oxidation stage, the higher-temperature area moved to the bottom rapidly and subsequently stayed approximately in the center of the coal; [Formula: see text], [Formula: see text] concentration and oxygen consumption increased sharply. In addition, the occurrence of higher-temperature area is accompanied by higher oxygen consumption. The obtained results show that higher air supply rate could shorten spontaneous combustion period and there exists a hyperbolic relationship between the temperature and time.
Highlights
Coal is one of the main energy sources in the world (Ren et al, 2019; Zhang et al, 2018a)
Better understanding of this topic has been successfully achieved. These results show that coal spontaneous combustion is impacted by a couple of factors, primarily consisting of particle size, oxygen concentration, air supply rate and temperature
To predict coal spontaneous combustion, it is necessary to analyze the precursors which would occur during the combustion process
Summary
Coal is one of the main energy sources in the world (Ren et al, 2019; Zhang et al, 2018a). In China, coal fire is one of the main hazards in coal mines, most of which were caused by coal spontaneous combustion This indicates that on one hand, a large amount of coal resources are wasted annually by coal fire; on the other hand, coal spontaneous combustion influences the coal production greatly. Better understanding of this topic has been successfully achieved These results show that coal spontaneous combustion is impacted by a couple of factors, primarily consisting of particle size, oxygen concentration, air supply rate and temperature. These results could provide convincing explanations in some aspects, it is not completely suitable for the real coal mines on account that some parameters can not be directly detected (Yang et al, 2018)
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