An experimental investigation of how coal's secondary oxidation process is impacted by primary oxidation temperature and ventilation

Abstract

A worldwide calamity has resulted from spontaneous coal combustion, and actions such as opening enclosed fire areas and processing coal left in mines can ignite oxidized coal. Using a procedural temperature rise testing system, the impact of various primary oxidation temperatures and ventilation rates on secondary coal oxidation was examined in this research. The variation laws of the indicator gas, characteristic temperature, and exothermicity parameters were mainly analyzed, and the activation energy of each stage in the low-temperature oxidation process was calculated. The findings demonstrate that the secondary oxidation process's trend of sign gases (CO and C2H4) and exothermic characteristic characteristics of coal with temperature is unaffected by the primary oxidation temperature and ventilation. Increasing ventilation reduces the indicator gas concentration and the coal's exothermic characteristic parameters in the initial stages of low-temperature secondary oxidation, whereas it has the reverse effect in the later stages. Stage Ⅰ of the secondary low-temperature combustion procedure is significantly influenced by ventilation and the first oxidation temperature, but stages Ⅱ and III are only marginally affected. When the coal is secondarily oxidized at low temperatures, primary oxidation reduces the Ea of stage I, while increased ventilation raises the Ea of stage I. T1 (critical temperature) rises as the airflow rate rises, whereas T2 (dry cracking temperature) falls. The findings can provide theoretical guidance to open enclosed fire areas and process coal left in mines and other goaf operations and can further enrich the theory of preventing and controlling secondary coal oxidation.