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采用Zeta Probe电位仪测定煤岩在不同溶液中的表面电动电位,分析了溶液浓度和pH值对煤岩表面电性的影响.基于DLVO理论,模拟计算了煤岩-溶液系统的分离压和微观润湿接触角.进行了不同pH值溶液的水相自吸实验,拟合获得了岩心尺度煤岩润湿接触角.微观尺度润湿性与自吸实验结果基本吻合,与岩心尺度润湿性在碱性环境下趋势相似,认为煤岩微观尺度和岩心尺度润湿性具有较强相关性.结果表明:溶液浓度不改变煤岩的等电点,随pH值增大煤岩表面电性由正电位变为负电位;溶液酸碱性影响微观接触角的大小,煤岩微观尺度润湿性随pH值增大逐渐趋于强水湿;毛细管压力受溶液酸碱性的影响,水相自吸能力随pH值增大而增强;岩心润湿接触角在pH值等于7附近出现最大值,溶液酸性和碱性增强其值均变小.
Zeta Probe Potentiometer was used to determine the surface electromotive potential of coal and rock in different solutions, and the effect of solution concentration and pH value on the surface electrical properties of coal and rock was analyzed. Based on DLVO theory, the separation pressure and microscopic Wetting contact angle.According to the water phase self-absorption experiment of different pH value solutions, the wetting contact angle of coal rock in the core scale was obtained by fitting.Microscopic wettability basically accorded with the self-absorption test results, The results show that the solution concentration does not change the isoelectric point of coal rock, and the surface electrical conductivity of coal rock increases with the increase of pH value The positive potential becomes negative potential; the acidity and basicity of solution affect the size of the micro-contact angle, and the wettability of micro-scale of coal and rock gradually becomes stronger and wetter with the increase of pH value; the capillary pressure is affected by the acidity and alkalinity of solution, The absorption capacity increased with the increase of pH value. The wetting contact angle of the core peaked at a pH value of about 7, and its acidity and alkalinity enhancement value decreased.