An investigation of airflow distribution and dynamics at a longwall mine face through field survey and its implication on oxygen depletion.

The airflow exchange between the mine ventilation system and the surface atmosphere can influence ventilation effectiveness and emit more greenhouse gas from the mine for shallow cover mines. This airflow exchange also changes the airflow dynamics at the ventilation system, specially at the tailgate corner of the longwall. In this study, the fix-point traverse technique was employed to conduct a comprehensive survey at a coal mine longwall face and tailgate region. The air velocity, oxygen and carbon monoxide concentrations, barometric pressure, and temperature were measured and surveyed. Based on the survey data, the airflow pattern and gas concentration were analyzed at return air corner on the tailgate side. Based on the measurement and analyses, it was found that the airflow at the face can be broken into two compartments by the hydraulic cylinder. These two compartments can periodically exchange the air at the face. This can influence the abnormal gas concentration for the release of carbon monoxide from the gob attributed from coal spontaneous combustion. Also, our study provided detailed information for more understanding of airflow in working face and gob by simulation method in the future work.