煤田地质与勘探2025，Vol.53Issue(11)：88-98,11.DOI:10.12363/issn.1001-1986.25.04.0281
煤矿采空区惰化煤结构演化及自燃活化机制
Structural evolution and spontaneous combustion and activation mechanisms of coals treated under inert atmospheres in a coal mine goaf
摘要
Abstract
[Objective]When used for the treatment of fire zones in deep coal mine goafs,low-oxygen and inertization techniques suffer from a scientifically blind spot,i.e.,the fire prevention and control bottleneck caused by a high sus-ceptibility to re-ignition of coals after being treated with high-temperature,low-oxygen(or inert)gas.To overcome this limitation,this study aims to systematically determine the mechanisms by which the evolution of the physical and chem-ical structures of coals after heat treatment under different atmospheres influences their spontaneous combustion and ac-tivation behavior.The purpose is to provide theoretical support for the treatment and safe opening of fire zones in a coal mine goaf.[Methods]This study investigated gas-bearing coals in the Zhujidong Coal Mine,Anhui Province.Using a series of techniques,such as the Fourier transform infrared spectroscopy(FTIR),specific surface area and pore size ana-lyses,thermal conductivity tests,and thermogravimetric analysis,this study systematically investigated the evolution of the chemical functional groups and changes in the pore structures in coal samples after heat treatment under atmo-spheres of 13%O2,N2,and CO2.In combination with low-temperature oxidation experiments,this study monitored the release patterns of indicator gases such as CO and C2H4,oxygen consumption rates,and exothermic intensities of these coal samples.Additionally,variations in the activation energy for coal spontaneous combustion were quantitatively as-sessed through kinetic parameter-based inversion.[Results and Conclusions]FTIR analysis revealed that coal samples after heat treatment under different atmospheres exhibited significantly decreased ―OH content and noticeably in-creased contents of C―O and C=O.Among these,samples treated under a CO2 atmosphere showed the most prominent effect of functional group reconstruction.Pore structure analysis suggests that coal samples after heat treatment exhib-ited significantly increased pore volumes and micropore specific surface areas,as well as improved pore connectivity.Most especially,samples treated under a CO2 atmosphere exhibited the most developed pores with pore sizes ranging from 2 nm to 50 nm,with a micropore volume increasing by 0.3 μL/g and micropore specific surface area reaching up to 1.56 m2/g.These samples were followed by those treated under a N2 atmosphere and then those treated under a 13%O2 atmosphere in this regard.The test results of thermophysical properties and low-temperature oxidation characteristics re-vealed a generally enhanced thermal conductivity and low-temperature oxidation activity of coal samples after heat treat-ment,as manifested by significantly increased volume fractions of CO and C2H4,elevated oxygen consumption rates,and enhanced exothermic intensities.Kinetic analysis demonstrated that the apparent activation energy of the coal samples treated under 13%O2,N2,and CO2 atmospheres decreased by 8.3%,17.6%,and 21.6%,respectively.Thermo-gravimetric analysis(TGA)further confirmed that the active temperature t3 of coal samples after heat treatment dropped by 2‒11℃.Furthermore,the mass loss rates in stages from t3 to t5 of the coal samples decreased in the order of those treated under CO2,N2,and 13%O2 atmospheres.These findings suggest that although heat treatment under inert atmo-spheres(especially CO2)can temporarily suppress oxygen,it could increase the tendency of coals to spontaneous combustion.In engineering,it is advisable to adopt N2 injection or N2-CO2 co-injection,supplemented by measures including temperature control,heat insulation,and fire suppression agents,to establish a multi-element fire prevention and re-ignition control system.This will help enhance the safety and long-term stability of the fire zones of coal mine goafs.关键词
煤自燃/孔隙结构/官能团/标志性气体/特征温度点/煤矿采空区Key words
spontaneous combustion of coal/pore structure/functional group/indicator gas/characteristic temperature point/coal mine goaf分类
矿业与冶金引用本文复制引用
张雷林,李婉婷,文辰辰..煤矿采空区惰化煤结构演化及自燃活化机制[J].煤田地质与勘探,2025,53(11):88-98,11.基金项目
国家自然科学基金项目(52474202,51874008) （52474202,51874008）
安徽省自然科学基金杰青项目(2408085J032) （2408085J032）
