6th INTERNATIONAL SYMPOSIUM ON MINE SAFETY SCIENCE AND ENGINEERING

109 / 2023-06-15 19:26:24

Study on the Underground Coal Fire — Surface Carbon Flux Response Mechanism under Complex Conditions

CCS,Coal,CO2,Flux,Surface Carbon Flux Response

Against the backdrop of China's "dual carbon" goals, while gradually controlling coal consumption and intensity, we are also actively implementing the control of CO2 emissions. With the promotion of the "dual control of energy" policy, the number of closed mines in China is increasing year by year. Due to the lack of effective management and the destruction of geological structures, there is a widespread phenomenon of air leakage in the goaf of these abandoned mines. As the time goes on, coal spontaneous combustion fires are prone to occur in goaf areas, causing waste of coal resources and generating a large amount of greenhouse gases, which will have a significant negative impact on controlling coal resource utilization and carbon reduction.

Based on the CCS/CCUS surface leakage monitoring method, this study takes the compound coal left spontaneous combustion area formed by the Haizhou Open pit Mine and the surrounding underground goaf as the object, and uses the intelligent Soil gas flux monitoring system to conduct seasonal, long-term, multi measurement point continuous monitoring of the CO2 gas flux on the overlying surface. The dynamic gas chamber method, statistical quantification method, Spatial analysis and other experimental methods are used to study the influence of residual coal combustion degree, formation fractures, environmental wind speed, soil moisture and other factors on the CO2 release, migration and surface response characteristics of underground coal fire, and then quantify the monitoring of regional CO2 emission. The results show that the burning of underground residual coal is the fundamental factor that triggers the abnormal response of surface carbon, and the carbon flux is positively correlated with the distribution of surface temperature caused by underground coal fires; Cracks are the main factor affecting the distribution of surface carbon flux, and wind speed is generally positively correlated with surface CO2 flux. The response of surface carbon flux caused by underground coal combustion is generally not affected by soil moisture, but the surge in soil moisture can cause significant fluctuations in surface carbon flux. The conclusion of this study has important practical significance for the control of natural fires, the prevention of geological disasters, the governance of living environments, and the suppression of greenhouse gas emissions.