Fan Jiuyuan, Li Jiangtao, Zhang Jiuling, Sun Chuyan, Yang Xiaotong, Xie Xiaoxiao, Wang Miaomiao
School of Emergency Management and Safety Engineering, North China University of Science and Technology, Tangshan, Hebei 063210, China.
Key Laboratory of Mining Development and Safety Technology, Tangshan, Hebei 063210, China.
ACS Omega. 2024 Aug 8;9(33):35950-35960. doi: 10.1021/acsomega.4c05278. eCollection 2024 Aug 20.
The stagnant water above the coal seam flows into the goaf, causing the goaf coal to be soaked by water for a long time. Compared with dry raw coal, water-soaked coal has a stronger tendency for spontaneous combustion, which poses a serious threat to mining operators. To unravel the impact of water immersion on coal's self-heating properties, an investigation was conducted employing techniques such as simultaneous thermogravimetric analysis/differential scanning calorimetry (TG/DSC), scanning electron microscopy (SEM), low-temperature nitrogen adsorption based on the BET theory, and Fourier transform infrared spectroscopy (FTIR). The variations in the characteristic temperature, microphysical structure, and active functional groups of bituminous coal with water immersion degrees of 10, 30, 50, and 100% were studied, and the experimental results showed that (1) during the initial stage of coal self-ignition oxidation, moisture can cause a delay in the characteristic temperature points of bituminous coal. When the degree of water saturation in bituminous coal reaches 100%, both the critical temperature ( ) and the cracking temperature ( ) peak at 48.14 and 205.06 °C, respectively. However, after the water evaporation phase is complete, water soaking promotes the spontaneous combustion of bituminous coal. (2) The number of pores and fractures in bituminous coal is positively correlated with the amount of water soaked, with the average pore diameter increasing from 10.124 nm in raw coal to 15.547 nm in the A coal sample. Moreover, when the degree of water immersion reaches 100%, the proportion of mesopores and macropores increases to 38.89 and 19.95%, respectively. (3) Compared to untreated coal, the number of functional groups in water-soaked coal samples increases. With the increase in water immersion, the hydroxyl (-OH) content of raw coal and four kinds of bituminous coal with different degrees of immersion was 40.8, 41.3, 42, 43.9, and 42.9%, respectively, showing a trend of increasing first and then decreasing. When the degree of water immersion of bituminous coal is 50%, the natural tendency is the strongest. These findings contribute to elucidating the underlying mechanism of water immersion's impact on coal self-ignition, thereby holding significant implications for enhancing fire safety measures in mine working areas.
煤层上方的积水流入采空区，导致采空区的煤长期被水浸泡。与干原煤相比，水浸煤的自燃倾向更强，这对采矿作业人员构成了严重威胁。为了揭示水浸对煤自燃特性的影响，采用同步热重分析/差示扫描量热法（TG/DSC）、扫描电子显微镜（SEM）、基于BET理论的低温氮吸附以及傅里叶变换红外光谱（FTIR）等技术进行了研究。研究了水浸程度分别为10%、30%、50%和100%的烟煤的特征温度、微观物理结构和活性官能团的变化，实验结果表明：（1）在煤自燃氧化初期，水分会导致烟煤特征温度点延迟。当烟煤的水饱和度达到100%时，临界温度（ ）和裂解温度（ ）分别在48.14和205.06℃达到峰值。然而，在水分蒸发阶段完成后，水浸促进了烟煤的自燃。（2）烟煤的孔隙和裂隙数量与水浸量呈正相关，平均孔径从原煤的10.124nm增加到A煤样的15.547nm。此外，当水浸程度达到100%时，中孔和大孔的比例分别增加到38.89%和19.95%。（3）与未处理的煤相比，水浸煤样中的官能团数量增加。随着水浸程度的增加，原煤和四种不同水浸程度烟煤的羟基（-OH）含量分别为40.8%、41.3%、42%、43.9%和42.9%，呈现先增加后减少的趋势。当烟煤的水浸程度为50%时，自燃倾向最强。这些发现有助于阐明水浸对煤自燃影响的潜在机制，从而对加强矿井作业区域的防火安全措施具有重要意义。
