[Bmim][BF_(4)]和硝酸协同效应对煤体微细观结构的影响

[Bmim][BF_(4)]and nitric acid synergistic effect on microstructure of coal

为了研究咪唑基离子液体在硝酸中的协同效应,首先利用硝酸(HNO_(3))溶液,1-丁基-3-甲基咪唑四氟硼酸盐([Bmim][BF_(4)])溶液及其混合溶液分别处理煤样,然后通过接触角实验测试各溶液的润湿性能,最后通过扫描电镜实验观测各溶液处理后煤样的孔隙-裂隙损伤。研究发现:单一溶液和复合溶液对煤样的润湿性和孔隙结构影响很大,复合溶液的协同效应使得煤中含氧官能团增加,煤样的芳香结构更加紧密,这和接触角的实验结果相同,复合溶液的煤尘接触角最小;另外通过扫描电镜对煤样表面的观察发现,相比单一溶液处理的煤样,协同效应下煤样的渗流网络通道更加发育,大量的次生裂隙沟通了渗流孔道。通过在余吾煤矿的工程实践中发现,经过压裂的钻孔瓦斯体积分数提高20%以上,瓦斯流量提高了1倍以上。

In order to study the synergistic effect of imidazole based ionic liquids in nitric acid,the coal samples were firstly treated with nitric acid(HNO_(3))solution,1-butyl-3-methylimidazoletetrafluoroborate([Bmim][BF_(4)])solution and its mixed solution respectively.Then the wettability of each solution was tested by contact angle experiment.Finally,the pore-crack damage of coal samples after each solution treatment was observed by scanning electron microscope experiment.The results found that single solution and composite solution have a great influence on the wettability and pore structure of coal samples,and the synergistic effect of composite solution increases the oxygen-containing functional groups in coal and makes the aromatic structure of coal samples more compact.This result is the same as the experimental result of contact angle,and the contact angle of coal dust in composite solution is the smallest.In addition,through the observation of coal sample surface by scanning electron microscope,it is found that the seepage network channel of coal sample under the synergistic effect is more developed than that of coal sample treated with single solution.In the engineering practice of Yuwu Coal Mine,the gas volume fraction of the borehole is increased by more than 20%,the gas flow rate increased by more than one times.