煤田地质与勘探2025，Vol.53Issue(6)：169-180,12.DOI:10.12363/issn.1001-1986.25.03.0181
低温氮气对褐煤孔隙结构与氧化特性的影响规律
Influencing patterns of low-temperature nitrogen on the pore structure and oxidation characteristics of lignite
摘要
Abstract
[Objective]During fire prevention and extinguishment for mines,injecting normal-temperature nitrogen into goaves can only play an inerting role.Meanwhile,the preparation of liquid nitrogen is complicated and costly.There-fore,in the Wudong Coal Mine in Xinjiang,low-temperature gaseous nitrogen of-40 ℃ was prepared using nitrogen cooling devices and then injected into goaves to prevent the spontaneous combustion of residual coals.However,the in-fluencing patterns of low-temperature nitrogen on the pore structures and oxidation characteristics of residual coals in goaves remain poorly understood.This tends to affect the prediction and forecast of the secondary oxidation of residual coals in goaves after low-temperature nitrogen injection ends.[Methods]Using experiments with an ultra-depth 3D di-gital microscope and a confocal laser scanning microscope(CLSM),nitrogen adsorption experiments,and temperature-programmed heating experiments,this study examined the surface morphologies,pore structures,and oxidation charac-teristic parameters of coals following sample processing using low-temperature nitrogen.[Results and Conclusions]After being processed using low-temperature nitrogen,the surface structures of coal samples were destroyed.With an in-crease in the processing time,the coal samples exhibited more developed reticular pore structures,and coal sample sur-faces displayed distinct undulations.The arithmetic mean height of various points on the surfaces gradually increased from 9.562 1 μm to 21.904 5 μm,with an increase of 1.29 times.Concurrently,the average height difference of all undu-lations rose from 81.321 0 μm to 193.146 5 μm,representing an increase of 1.36 times.Low-temperature nitrogen primarily affected the distribution of micropores and mesopores in the coal samples,especially 2-4 nm mesopores.With an increase in the sample processing time,micropores in the samples trended upward and then downward,while meso-pores therein showed an opposite trend.As a result,the total pore volume increased by 0.004 3 cm3/g,with the 2-10 nm mesopores identified as the largest contributor,and the specific surface area of coal samples determined using the Brun-auer-Emmett-Teller(BET)theory increased by 0.049 3 m2/g.After sample processing using low-temperature nitrogen,the CO production,heat release intensity,and oxygen consumption rates significantly increased during coal sample oxid-ation.Notably,their increments increased with the sample processing time.Specifically,the CO production,oxygen con-sumption rate,and maximum heat release intensity increased by 5.02×104 μL/L at maximum,2.33×10-8 mol/(cm3s),and 2.25×10-2 J/(cm3·s),respectively.Additionally,the characteristic temperature of oxidation reactions in the coal samples decreased.The results of this study reveal that low-temperature nitrogen can destroy the pore structures of coals and enhance their oxidation performance.In the case where low-temperature nitrogen of-40 ℃ is injected into a goaf,its macroscopic dominant effect of inerting and cooling can effectively suppress the spontaneous combustion of coals.When oxygen is restored after nitrogen injection ends,coals show a higher tendency for spontaneous combustion after being treated due to the microscopic side effect of low-temperature nitrogen,enhancing the secondary oxidation intens-ity.关键词
煤自燃/低温氮气/表面形貌/孔隙结构/氧化特性Key words
coal spontaneous combustion/low-temperature nitrogen/surface morphology/pore structure/oxidation characteristic分类
矿业与冶金引用本文复制引用
解树亮,王刚,屈庆栋,刘浩,孙路路..低温氮气对褐煤孔隙结构与氧化特性的影响规律[J].煤田地质与勘探,2025,53(6):169-180,12.基金项目
国家自然科学基金项目(52174194) （52174194）
