Experimental Study on Inhibition of Spontaneous Combustion of Coal with Different Metamorphic Degree by CO2

Abstract

To study the oxidation heating process and molecular structure characteristics of coal in CO₂ atmosphere, the characteristic temperature, activation energy, and functional group evolution laws of three kinds of coal with different degrees of metamorphism were studied by thermogravimetric and Fourier infrared spectroscopy experiments, and the dynamic change process of kinetic parameters with temperature was obtained. The results showed that in the CO₂ atmosphere, the temperature range of the three coal combustion stages presents “lag”; Compared with the air atmosphere, the ignition temperature, combustion temperature and maximum weight loss temperature increase. CO₂ inhibits the process of coal combustion. In an inert atmosphere, the combustibility of coal decreases. The lower the metamorphic degree of coal, the lower the characteristic temperature, the more unstable the molecular structure, and the lower the activation energy required for oxidation. With the increase of metamorphism, the inhibition ability of CO₂ was enhanced. By contrast analysis of infrared spectrum, it is found that raw coal has more active groups and higher oxidation activity than coal under inert atmosphere. The inhibition of CO₂ on coal spontaneous combustion is revealed by the increase of combustion and activation energy and the decrease of active functional group.