利用多手段探究粒径对超细煤粉孔隙结构的影响

The Influence of Particle Sizes on Pore Structure of Superfine Pulverized Coal Investigated by Multiple Means

煤粉的孔隙结构会对其利用过程会产生重要影响,采用多种手段对其进行表征能更好地反应孔隙结构特征。选用内蒙古(NMG)烟煤和河南(HN)无烟煤,并磨制加工成不同粒径的超细煤粉。利用N_(2)吸附、CO_(2)吸附、压汞法以及小角散射(SAXS)对超细煤粉孔隙结构随粒径的变化规律进行了探究。BJH模型表明:随着粒径的减小,HN无烟煤孔径大于5 nm的中孔孔容积呈现增加的趋势,NMG烟煤的中孔孔容积呈现先增加后不变的趋势。随着粒径的减小,NMG烟煤及HN无烟煤2种煤样品的微孔比表面积及孔容都呈现出了先增加后减小的趋势,拐点粒径在14μm左右,这说明随着粉碎过程进行到一定程度后,微孔孔隙并不呈现持续发展的状态,微孔的塌陷与收缩趋势逐渐占据主流。压汞测试表明:粉碎过程会使中孔和大孔孔隙表面粗糙度增加。SAXS测试表明:粉碎过程在整体上会使孔隙表面粗糙度降低。超细化粉碎过程会对煤的微孔、中孔、大孔等全部孔隙结构产生影响。

The pore structure of pulverized coal can insert an important impact on its utilization process,which can be characterized in detail by using various methods.Inner Mongolia(NMG)bitumite and Henan(HN)anthracite were ground into superfine coal powder with different particle sizes.N_(2) adsorption,CO_(2) adsorption,mercury intrusion and small angle X-ray scattering(SAXS)were applied to explore the influence rule of the particle sizes on pore structures.BJH theory demonstrates that,with the decrease of particle sizes,the pore volume of HN anthracite with pore size greater than 5 nm shows an increasing trend,while the pore volume of NMG samples increases first and then remains unchanged.With the particle sizes decreasing,the specific surface area and pore volume of micropores of the two samples increase first and then decline.The inflection point particle size is around 14μm.It shows that as the grinding process comes to a certain extent,the micropore structure is not always in a development state,and the collapse of pores and shrinkage trend gradually become the mainstream.Mercury intrusion test proves that the surface roughness of mesoporous and macroporous pores increases during comminution,while SAXS test reveals that the surface roughness of the whole pores descends during the comminution process.The superfine grinding process will affect all the pore structures in the coal,including micropores,meso-pores and macropores.