Investigation into the spontaneous combustion characteristics and microstructure change of pre-oxidation coal

ABSTRACT

To study the macro and micro characteristics of the spontaneous combustion of pre-oxidation coals (POC) with different pre-oxidation temperatures (80°C, 120°C, 160°C, 200°C), we used programmed temperature experiments, BET, and in situ FTIR. The results show that the spontaneous combustion characteristic parameters (oxygen consumption rate, gas release rate (CO and CO₂), and exothermic intensity) of POC show disparities. Especially after the functional group content of coals reaches the extreme value at 160°C, the differences are further enlarged. Different primary oxidation processes change the specific surface area (SSA) and functional group content to varying degrees. The 80°C pre-oxidation process increases SSA and functional group content. 80°C POC reacts more violently than Y (raw coal), which can produce more reducing groups (-OH, -CH_3, and -CH₂-) and lower oxidizing groups (C = O and -COO-), showing a stronger ability to combine with oxygen. Moreover, it consumes more oxygen and releases more CO, CO_2, and heat. The macro and micro spontaneous combustion characteristics of 200°C POC are the weakest. It can be judged that the coal under a pre-oxidation temperature of 80°C has a stronger tendency to spontaneous combustion, and the pre-oxidation process at 200°C reduces the tendency of coal to spontaneous combustion.

KEYWORDS:

• Spontaneous combustion
• Pre-oxidation temperature
• Characteristic parameters
• Pore structure
• FTIR micro-characteristics

Acknowledgments

This work was funded by the Natural Science Foundation of China (Grant No. 51474106, Grant No. 51874131 and Grant No. 52174163).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions

SL designed the research. YB, YY and YZ performed research and initially analyzed data. HN analyzed the data further and drafted the initial manuscript. WJ and SL revised and approved the manuscript. All authors read and approved the final manuscript.

Additional information

Funding

This work was supported by the the Natural Science Foundation of China [51474106,51874131,52174163].