碱液处理对褐煤孔隙结构的影响

Effect of alkali treatment on the pore structure of lignite

为降低褐煤吸水性,选用不同浓度氢氧化钠溶液处理煤样.应用氮气吸附法、扫描电子显微镜(SEM)等对处理前后煤样进行分析表征,探求不同浓度碱液处理对锡林浩特褐煤孔隙结构的影响.结果表明:氢氧化钠浓度低于0.05mol/L时,煤样比表面积与原煤相比有所增加,浓度继续增加则会减小;总孔体积在碱浓度低于0.01mol/L时稍有增加,之后均比原煤小,大于0.5mol/L时总孔体积不再大幅变化;在0.01～0.5mol/L时,随着氢氧化钠浓度增加,处理后煤样的孔隙分布在中、微孔各孔径区域内均逐渐减少,其大孔相应增加;吸脱附等温线解析结果表明,碱浓度在0.001～0.05mol/L时,对其孔形产生影响较小,在0.1～1mol/L时,较小孔径范围内开始出现开放性小孔,并形成裂缝形孔.

To lower its hydroscopicity, the lignite was treated with different concentrations of sodium hydroxide. Nitrogen adsorption method and scanning electron microscope （SEM） were used to study the effect of treatment conditions on pore structure of Xilinhaot lignite. The re- sults show that the surface areas of treated sample increased compared with that of raw coal when the sodium hydroxide concentration is less than 0.05 mol/L, and the surface areas de- creased when the concentration increase continuously. The total pore volumes decreased when alkali concentrations of 0.01--0. 5 tool/L, and increased slightly when alkali concentrations are less than 0.01 mol/L. With the increasing of sodium hydroxide concentration between 0.01 and 0.5 mol/L, both the mesoporous and mieroporous amount were gradually reduced, and the macroporous increased correspondingly. The adsorption-desorption loops imply the appearing of opening holes with smaller size and crack-shaped when alkali concentrations of 0.1--1 mol/ L, but less effect happened when alkali concentrations of 0. 001--0.05 mol/L.