表面活性剂辅助酸化条件下煤体润湿溶蚀实验研究

Experimental Study on Wetting and Dissolutionof Coal under Surfactant-assisted Acidification Conditions

煤体润湿-酸化是煤尘治理和瓦斯防治的一种有潜力的化学改性方法。为进一步了解煤体润湿-溶蚀内部转化机理,采用接触角测试与低温氮气吸附实验,探究酸液和表面活性剂复合试剂处理前后煤体润湿特性以及孔隙结构的变化。结果表明:表面活性剂辅助酸化条件下煤体接触角能降低60%左右,大幅度改善煤体润湿性;经复合试剂处理之后,煤体内部发生化合反应改变了煤的孔隙结构,使煤样总孔容和平均孔径分别增大2.0倍和1.5倍;结合分形理论,分形维数D1和D2较原煤分别减小24.1%与10.3%,煤体表面粗糙度降低,孔隙连通性增强;[BMIM]BF4离子液体的加入抑制表面活性剂的活性导致接触角增加,煤体的润湿性减弱,进而使煤体的平均孔径降低;煤体的润湿性与溶蚀性存在一定的正相关关系,随着润湿性的增强,促进酸液溶解更多的矿物杂质,使煤体的总孔容和平均孔径随之增加。

Coal body wetting-acidification represents a promising chemical modification method for coal dust control and gas prevention.To further understand the internal transformation mechanism of coal body wetting-dissolution,contact angle tests and low-temperature nitrogen adsorption experiments were employed to investigate changes in coal body wetting characteristics and pore structure before and after treatment with acid solution and surfactant composite reagents.The results showed that under surfactant-assisted acidification,the contact angle was reduced by approximately 60%,greatly improving coal wettability.After treatment with composite reagents,chemical reactions within the coal body altered its pore structure,increasing total pore volume and average pore diameter by 2.0 and 1.5 times,respectively.In combination with the fractal theory,fractal dimensions D 1 and D 2 decreased by 24.1%and 10.3%compared to raw coal,indicating reduced surface roughness and enhanced pore connectivity.The addition of BF 4 ionic liquid inhibited surfactant activity,leading to increased contact angles and weakened coal wettability,consequently reducing average pore diameter.A positive correlation existed between coal body wettability and dissolution;as wettability increases,it promoted the dissolution of more mineral impurities by acid solution,resulting in the increase of total pore volume and average pore diameter.