Effect of Igneous Intrusion on Adsorption Characteristics of Coal to Gas

摘要： 为了研究岩浆侵入对煤吸附瓦斯特性影响，以卧龙湖井田10煤11个煤样为研究对象，采用工业分析、等温吸附实验、液氮吸附法测BET比表面积和CO2吸附法测微孔等方法，对比分析了多元物性参数和煤样与火成岩距离的关系。结果表明：岩浆热演化范围为60 m左右。靠近岩浆岩，镜质组反射率Rm由2.74%增至5.03%，挥发分Vdaf由16.04%减至6.85%，煤的变质程度提高。吸附常数a有先增加后减小的趋势，8#煤样（热演化区）a=59.02 m3/t，为最大值。岩浆覆盖区1#煤样a=13.53 m3/t，为最小值。吸附常数a、BET比表面积和微孔孔容分布曲线相关性较好，从数值大小来看，热演化区高于正常区，正常区高于岩浆覆盖区。岩浆接触变质作用，降低了煤吸附瓦斯能力。岩浆侵入煤层使热演化区煤的微孔较发育，比表面积变大，瓦斯吸附位增多，煤的吸附瓦斯能力增强。

关键词: 岩浆侵入, 煤的吸附特性, 镜质组反射率, BET比表面积, 微孔孔容

Abstract: In this paper，to study the effect of igneous intrusion on adsorption characteristics of coal to gas，taking 11 samples of No.10 coal seam in Wolonghu coalfield as research object，we compares and analyzes the relationship between the multivariate physical properties of coals and the distances from coal samples to igneous rocks，by synthetically using the methods of industrial analysis，CH4 isothermal adsorption experiments，BET surface area calculated by liquid nitrogen adsorption method，and micro-pores measured by CO2 adsorption method．The results show that the thermal evolution area of magmatic is about 60 m．When approaching the igneous rocks，the vitrinite reflectance (Rm) increases from 2.74% to 5.03%，the volatile matter decreases from 16.04% to 6.85%，and the metamorphic grade of coal increases．Meanwhile，the adsorption constant (a) increases first and then decreases，while the maximal adsorption constant (No.8 coal sample in thermal evolution area) is 59.02 m3/t，and the minimal value (No.1 sample in magmatic covering area) is 13.53 m3/t．In addition，there is good relativity among the distribution curves of adsorption constant，BET surface area，and micro-pore volume．Furthermore，the numerical values in thermal evolution area are higher than that in normal area，while the values in normal area are higher than that in magmatic covering area．Moreover，the  adsorption ability of coal to gas is reduced because of the contact metamorphism of magmatic，however，duo to the igneous intrusion，the micro-pores of coal samples in thermal evolution area are more development，BET surface area is more larger，gas adsorption positions increase，and the adsorption ability of coal to gas is enhanced．

Key words: igneous intrusion, adsorption characteristics of coal, vitrinite reflectance, BET surface area, micro-pore volume