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<p>This paper investigated the variation patterns of microscopic active groups and macroscopic gas and heat production of oxidized coal formed during cooling under different gas atmospheres, revealing the influence of cooling atmospheres on the spontaneous combustion characteristics of oxidized coal. The main conclusions are as follows: When the primary oxidation temperature did not exceed the critical temperature of 130&#xa0;°C, the differences in g factor and the growth rate of radical concentration between oxidized coal-N<sub>2</sub> and oxidized coal-dry air during reoxidation were minimal. Beyond 130&#xa0;°C, oxidized coal-N<sub>2</sub> exhibited significantly higher g factor values and greater growth rates of radical concentration in later reoxidation stages compared to oxidized coal-dry air. At primary oxidation temperatures below 130&#xa0;°C, the influence of cooling atmosphere on fatty hydrocarbon depletion and oxygen-containing functional group formation during reoxidation remained limited. Notably, once the temperature surpassed 130&#xa0;°C, oxidized coal-dry air exhibited reduced consumption of methyl/methylene groups and suppressed generation of ether bonds, carbonyl groups, and carboxyl groups in later reoxidation phases compared to oxidized coal-N<sub>2</sub>. The crossing point temperature during reoxidation initially decreased then increased with the rise in primary oxidation temperature, reaching its minimum at 130&#xa0;°C. Oxidized coal-N<sub>2</sub> exhibited lower crossing point temperatures during reoxidation than oxidized coal-dry air. When the primary oxidation temperature exceeded 130&#xa0;°C, CO emissions from re-oxidized coal exceeded those from raw coal in early reoxidation stages but became lower in later stages. Oxidized coal-N<sub>2</sub> demonstrated higher CO emissions than oxidized coal-dry air during reoxidation, with this difference becoming particularly pronounced when primary oxidation temperatures exceeded 130&#xa0;°C. The distinct consumption of active groups during the cooling phase of the initial oxidation is the primary reason for the characteristic differences between oxidized coal-dry air and oxidized coal-N<sub>2</sub> during reoxidation. These findings provide theoretical guidance for preventing and controlling oxidized coal spontaneous combustion in mine gobs.</p>

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The spontaneous combustion characteristics of oxidized coal formed by cooling under different gas atmospheres

  • 期刊论文

  • 发表日期：

    2025年5月26日

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  • Xiaoyuan Jiang,
  • Long Ma,
  • Shengqiang Yang,
  • Jiawen Cai,
  • Buzhuang Zhou

摘要

This paper investigated the variation patterns of microscopic active groups and macroscopic gas and heat production of oxidized coal formed during cooling under different gas atmospheres, revealing the influence of cooling atmospheres on the spontaneous combustion characteristics of oxidized coal. The main conclusions are as follows: When the primary oxidation temperature did not exceed the critical temperature of 130 °C, the differences in g factor and the growth rate of radical concentration between oxidized coal-N2 and oxidized coal-dry air during reoxidation were minimal. Beyond 130 °C, oxidized coal-N2 exhibited significantly higher g factor values and greater growth rates of radical concentration in later reoxidation stages compared to oxidized coal-dry air. At primary oxidation temperatures below 130 °C, the influence of cooling atmosphere on fatty hydrocarbon depletion and oxygen-containing functional group formation during reoxidation remained limited. Notably, once the temperature surpassed 130 °C, oxidized coal-dry air exhibited reduced consumption of methyl/methylene groups and suppressed generation of ether bonds, carbonyl groups, and carboxyl groups in later reoxidation phases compared to oxidized coal-N2. The crossing point temperature during reoxidation initially decreased then increased with the rise in primary oxidation temperature, reaching its minimum at 130 °C. Oxidized coal-N2 exhibited lower crossing point temperatures during reoxidation than oxidized coal-dry air. When the primary oxidation temperature exceeded 130 °C, CO emissions from re-oxidized coal exceeded those from raw coal in early reoxidation stages but became lower in later stages. Oxidized coal-N2 demonstrated higher CO emissions than oxidized coal-dry air during reoxidation, with this difference becoming particularly pronounced when primary oxidation temperatures exceeded 130 °C. The distinct consumption of active groups during the cooling phase of the initial oxidation is the primary reason for the characteristic differences between oxidized coal-dry air and oxidized coal-N2 during reoxidation. These findings provide theoretical guidance for preventing and controlling oxidized coal spontaneous combustion in mine gobs.