矿井煤尘的分形特征及对其表面润湿性能的影响

基于光学接触角测量仪研究了不同煤质、不同粒度煤尘对去离子水以及添加羧甲基纤维素钠（CMC）、十二烷基硫酸钠（SDS）等表面活性剂时的润湿接触角，同时基于非线性的分形理论对煤尘粒度、表面孔隙结构等分形特征进行了研究，分析了粒度及表面结构分形维数对颗粒表润湿特性的影响。结果显示，细化煤尘表现为较强的疏水性，0.2%的表面活性剂可显著改善颗粒表面的润湿性能，其中以阴离子表面活性剂（SDS）为佳；煤尘的粒度分布、颗粒表面的孔隙结构均表现出典型的分形特征；随着粒度分形维数的增加，颗粒中位粒径降低，其表面的润湿接触角增加，特别是对于粒径小于10 μm的煤尘较为显著；随着表面孔隙分形维数的增加特别是对于分形维数大于2.5时，表面润湿接触角逐步减小并趋于稳定。

Fractal characteristics of particle size distribution and its effects on the surface wetting performance of coal mine dusts

The wetting contact angles of coal dust with deionized water or added surfactants such as CMC or SDS were measured.The effects of coal rank and the particle size distributions were discussed.Based upon the fractal theory,the non-linear characteristics of dust particle size distributions and particles micro porous structures were analyzed.Also,the relationship between the fractal dimensions of coal physical character and wetting contact angles were correlated.Research results show that the finer coal particle presents stronger hydrophobic,and the 0.2% surfactants such as CMC and SDS can greatly improve the wetting property of coal dust with liquid,which the anionic surfactant(SDS) performs better.The particle size distributions and micro porous structure of coal dust shows typical fractal characteristics accordingly.With the increase of dust size distribution fractal dimension,the median diameter of dust decreases and its wetting contact angles increase greatly,especially for the dust whose sizes are smaller than 10 μm.With the increase of porous fractal dimension,the wetting contact angles decrease gradually and tend to stabilization when the porous fractal dimensions are larger than 2.5.