氧化煤低温氧化特性及演化规律

为了探究氧化煤的低温氧化特性及演变规律，采用程序升温实验系统，对平煤八矿煤样分别预氧化至60 ℃、90 ℃、120 ℃、150 ℃、180 ℃、210 ℃时通入N₂绝氧降温形成的氧化煤，进行低温氧化程序升温实验；为进一步揭示不同灭火条件下形成的氧化煤低温氧化行为特征，对煤样预氧化至120 ℃时，通入3种不同体积分数N₂灭火后形成的氧化煤，开展低温氧化程序升温测试，测定这两类氧化煤低温氧化过程耗氧速率、标志性气体(CO、CO₂)产生率以及放热强度的变化规律。结果表明:氧化煤的耗氧速率、标志性气体产生率和放热强度均小于原煤；预氧化至90 ℃煤样的自燃特性参数更接近原煤，说明预氧化至临界温度的煤更易发生复燃；而预氧化至120 ℃时通入N₂的体积分数越高，这类氧化煤的自燃特征参数越接近原煤，说明通入N₂体积分数越高的煤复燃能力越强。因此，开采近距离煤层群、复采工作面以及启封火区等区域的煤体时，应防范其发生复燃。

Characteristics and evolution law of low-temperature oxidation of oxidized coal at recrudescence stage

In order to explore the low-temperature oxidation characteristics and evolution law of oxidized coal, this paper adopted a temperature-programmed experiment system. Firstly, the low-temperature oxidation temperature-programmed experiment was carried out on the oxidized coal formed by N₂ anaerobic cooling after the coal samples were pre-oxidized to 60 ℃, 90 ℃, 120 ℃, 150 ℃, 180 ℃ and 210 ℃ respectively. At the same time, in order to further reveal the characteristics of low-temperature oxidation behavior of oxidized coal formed under different fire extinguishing conditions, the low-temperature oxidation temperature programmed test was carried out on the oxidized coal formed after fire extinguishing with three different volume fractions of N₂ when the coal sample was pre-oxidized to 120 ℃. This reveals the changes of oxygen consumption rate, production rate of signature gases (CO, CO₂) and heat release intensity of these two kinds of oxidized coals during low temperature oxidation process. The results show that the oxygen consumption rate, signature gas generation rate and heat release intensity of oxidized coal are all lower than those of raw coal. Furthermore, the spontaneous combustion characteristic parameters of coal samples pre-oxidized to 90 ℃ are closer to that of raw coal, indicating that coals pre-oxidized to critical temperature are more likely to reignite. When pre-oxidized to 120 ℃, the higher the volume fraction of N₂, the closer the spontaneous combustion characteristic parameters of this oxidized coal are to the original coal, indicating that the coal with higher volume fraction of N₂ has stronger recrudescence ability. Therefore, it is necessary to prevent the recurrence of coal when mining the coal body in the near coal seam group, the recrudescence working face and the unsealing fire area.