Impact of Airflow and Temperature on Coal Secondary Oxidation-Induced Spontaneous Combustion Risk

Increasing mining depths heightens the spontaneous combustion (SC) risk of coal in goafs due to elevated ground temperatures. This study examines the coupled effects of airflow and thermal pretreatment on secondary oxidation. Experiments were conducted on coal samples pretreated at 35, 50, and 65 °C under airflow rates of 50-200 mL/min. Results demonstrate that airflow rate and pretreatment temperature interact synergistically: low airflow (50-100 mL/min) increased activation energy and suppressed oxidation in 50 °C treated coal, whereas high airflow (150-200 mL/min) enhanced reactivity in 35 and 65 °C samples. Medium airflow (100-150 mL/min) served as a critical transition zone, differentially inhibiting or promoting oxidation based on pretreatment temperature. The "50 °C pretreatment + 200 mL/min airflow" combination particularly facilitated complete oxidation, yielding high CO₂ emissions. These insights are crucial for developing targeted ventilation strategies in deep mining goafs.