Influence of coal composition on heat storage and spontaneous combustion characteristics

Abstract

Based on the caving characteristics of coal and rock in goaf, through the analysis of thermal physical parameters and oxidation kinetics of coal and rock mixed components, the viewpoint of changing thermal storage parameters, temperature rise oxidation process and activation energy of caving coal and rock components and mixed lithology is proposed. The thermal conductivity measurement experiment shows that the thermal conductivity increases gradually with the increase of mixing proportion after the overburden is mixed with coal; and the thermal conductivity of mixed samples increases greatly when the rock component content is more than 50%; the lithology of overburden is different, and the difference of mixed components is obvious. Under the same proportion, the thermal conductivity of 50% mudstone is 0.12 W/(m·K), and that of siltstone is 0.14 W/(m·K). Thermogravimetric test shows that the increase of rock composition leads to the decrease of weight loss rate, and the main characteristic temperature point and activation energy increase, in which the activation energy of siltstone component is higher than that of mudstone component; in addition, when the composition of coal and rock is less than 10%, the increase of activation energy is small; when the composition is between 10% and 70%, the activation energy of mudstone increases from 28.18 kJ/mol to 35.28 kJ/mol, the increase of activation energy is large, which is lower than that of siltstone. When the composition of coal and rock is more than 70%, the increase trend of activation energy becomes slow.

Keywords

• spontaneous combustion
• coal and rock components
• thermal conductivity
• characteristic point temperature
• activation energy