不同温度下可溶有机质对煤电阻率的影响

The effect of soluble organic matter on coal resistivity at different temperatures

摘要:

煤中可溶有机质能改变煤的孔隙结构,进而影响煤的电阻率,为得到煤中存在的可溶有机质对煤电阻率的影响规律,选取3种不同变质程度的60～80目的原煤煤粒,采用乙酸乙酯作为溶剂来萃取煤中可溶有机质,萃取时间取4、8、12、16、20、24 h,将萃取前后的煤粒制成型煤,在10 ℃～90 ℃温度条件下,利用CHI660E型电化学工作站测试煤样的I-V曲线,并计算出电阻率,分析和研究不同温度下煤电阻率受可溶有机质的影响机理和规律.结果表明:在10 ℃～90 ℃温度范围内和萃取时间为0~24 h时,煤中可溶有机质的存在可明显提高煤电阻率1.31～1.74倍,煤电阻率随萃取时间的增大（煤中可溶有机质含量减少）的变化符合Sigmoid函数关系,且只会在一定的区间内变化；煤电阻率随温度的升高呈现抛物线规律,萃取前后煤电阻率的比值随温度的升高近似呈现Lorentzian函数分布,在40 ℃～50 ℃时出现拐点；可溶有机质对煤电阻率影响的敏感性和相关性随煤变质程度的提高而逐渐减弱.

Abstract:

To investigate the influence law of soluble organic matter in coal on coal resistivity, briquette coals of three different metamorphic grades made of 60~80 purpose raw coal grains were selected and tested. Ethyl acetate was used as solvent to dissolve soluble organic matter in the coals at 4,8, 2,6, 0,4 h. The coals before and after dissolution were made into sample coals. The current vs. voltage curves of the sample coals were obtained at 10 ℃~90 ℃ using CHI660E electrochemical workstation and their resistivity were calculated. Based on this, the influence mechanism and rule of the soluble organic matter on coal resistivity at different temperatures were analyzed. Results show that the presence of soluble organic matter in coal increased coal resistivity for 1.31~1.74 times at temperatures from 10 ℃~90 ℃ in 0 ~24 h dissolution time. The rule that coal resistivity increased with the increase of dissolution time conforms to the Sigmoid Function relation, and coal resistivity only changed according to this rule within a certain range. Coal resistivity increasing with temperature rise exhibits parabolic rule. The ratio of coal resistivity before and after dissolution increasing with temperature rise approximately presents Lorentzian distribution with a turning point at 40 ℃~50 ℃. The sensitivity and correlation of the influence of soluble organic matter on coal resistivity gradually weakened with the increase of the degree of coal metamorphism.