Abstract

To study the multi-field coupling mechanism of gas and coal spontaneous combustion, low-temperature nitrogen adsorption and SEM were applied to carry out microstructure testing experiments on oxidation of gas-bearing coal in this paper. And a pore fractal calculation model incorporating pore size distribution was established. The effects of low-temperature oxidation and gas ad/de-sorption on the change of coal pore structure were investigated. The results showed that the pore volume and specific surface area of JJK and YJL with different pretreatment conditions were similar in trend, adsorption–desorption process further attenuates the ability of the coal pore to resist the thermal damage, V₁ and V₂ of JJK-3 and YJL-3 decreased by 0.199, 0.212 and 1.88, 4.214 × 10^–3 cm³·g⁻¹, respectively. The pore fractal model based on pore size distribution characteristics was found, and the D_fb of JJK-3 and YJL-3 was 2.23 and 2.33, respectively, which were higher than that of JJK-2 (2.20) and YJL-2 (2.05). The coupling effect of desorption of gas and oxidation was stronger than the effect of oxidation on pore modification. The gas storage state of gas-bearing coal and the distribution of desorbed gas in goaf were affected by change of pore structure, so that the oxidation of gas-bearing coal can be weakened and the risk of spontaneous combustion of gas-bearing coal can be declined, which can provide a theoretical basis for the judgment of the risk of spontaneous combustion of gas-bearing coal in goaf.

中文翻译：

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含瓦斯煤低温氧化微观结构分形特征实验研究

摘要

为了研究瓦斯与煤自燃的多场耦合机理，本文采用低温氮气吸附和扫描电镜开展含瓦斯煤氧化微观结构测试实验。并建立了考虑孔径分布的孔隙分形计算模型。研究了低温氧化和瓦斯吸附/解吸对煤孔隙结构变化的影响。结果表明，不同预处理条件的JJK和YJL的孔容和比表面积趋势相似，吸附-解吸过程进一步削弱了煤孔隙抵抗热损伤的能力，JJK-的V ₁和V ₂ 3和YJL-3分别减少了0.199、0.212和1.88、4.214×10 ^–3 cm ³ ·g ^-1。建立了基于孔径分布特征的孔隙分形模型，JJK-3和YJL-3的D _fb分别为2.23和2.33，高于JJK-2（2.20）和YJL-2（2.05） ）。气体解吸与氧化的耦合效应强于氧化对孔隙改性的影响。孔隙结构的变化影响瓦斯煤的储气状态和采空区解吸瓦斯的分布，从而减弱瓦斯煤的氧化作用，降低瓦斯煤自燃的风险。下降,可为采空区含瓦斯煤自燃风险的判断提供理论依据。