有机质与矿物质表面润湿性差异调控对低阶煤可浮性促进作用机制

Strong hydrophilicity of the surface of organic matter and minerals in low rank coal is the main reason resulting in poor flotability. Non-ionic surfactants are easily adsorbed on oxygen-containing functional groups of organic matter surface in coal by hydrogen bonding, whereas the adsorption of non-ionic surfactants interacting with minerals surface is weak. Based on the difference of surfactant adsorption interaction on the surface of organic matter and minerals, enhancing the selective preferential adsorption of surfactants on the organic matter would bring its wettability alteration from hydrophilicity to hydrophobicity and increase the surface wettability difference between the organic matter and the minerals in coal. Ultrasonic desorption method is used to remove the surfactant adsorbed with weaker acting force on minerals surface, which is expected to further increase the wettability difference between the organic matter and the minerals. The key objective of this research project is enhancing the surface hydrophobicity of the organic matter in low rank coal and increasing the surface wettability difference between the organic matter and the minerals in coal. In order to achieve this goal, it is needed to investigate the selective adsorption difference of non-ionic surfactants on organic matter and minerals in low rank coal, the desorption of surfactants on minerals under ultrasonic treatment, the correlation and synergism between the adsorption and spreading of collector on coal and variation of surface wettability of organic matter and minerals in coal, and also the effect of difference regulation of wettability on its floating performance. The theory and control method of improving low rank coal flotability based on surface wettability difference regulation and control for the organic matter and the minerals in low rank coal would be available, which laid a theoretical foundation for promoting the development of clean and efficient utilization technology of low rank coal.

低阶煤中有机质与矿物质表面均呈现强亲水性是导致其可浮性差的主要原因。利用非离子表面活性剂与煤中有机质上含氧官能团易发生氢键吸附，而在矿物质表面吸附作用力较弱的差异，通过强化表面活性剂在有机质上的选择性优势吸附，提高煤中有机质表面疏水性的同时，扩大有机质和矿物质表面润湿性的差异。采用超声处理脱附以弱作用力吸附到矿物质上的表面活性剂，进一步强化有机质和矿物质表面润湿性的差异。围绕扩大低阶煤中有机质和矿物质表面润湿性差异核心研究目标，研究非离子表面活性剂在低阶煤中有机质和矿物质上吸附选择性差异；矿物质上吸附的表面活性剂在超声辅助的脱附；煤中有机质和矿物质表面润湿性差异变化规律与捕收剂在煤上各组分吸附、铺展的关联性和协同作用，以及润湿性差异调控对其上浮性能的影响，形成基于低阶煤中有机质与矿物质表面润湿性差异调控来促进其浮选有效分离的理论和方法，为推动低阶末煤分质清洁高效利用技术的发展奠定理论基础。

低阶煤中有机质上的含氧官能团较为丰富，亲水性强，低阶煤中有机质与矿物质表面均呈现强亲水性是导致其可浮性差的主要原因。项目围绕非离子表面活性剂在低阶煤中有机质表面上的选择性吸附，扩大低阶煤中有机质和矿物质表面润湿性差异核心研究目标，系统地研究低阶煤中有机质和矿物质对非离子表面活性剂吸附的差异性和界面作用机理，阐明了不同疏水基结构非离子表面活性剂在低阶煤中有机质和矿物质上吸附选择性规律和扩大有机质和矿物质表面润湿性差异的调控机理。超声辅助下选择性脱附去除矿物质吸附的表面活性剂后，在精煤产率基本不变的情况下，精煤灰分有所降低。研究润湿性差异性调控对非极性烃类油捕收剂在煤上的吸附分布和铺展的影响发现，表面活性剂调控低阶煤表面润湿性和强化药剂分散性分别通过增大烃类油与低阶煤表面的相互作用强度，改变油滴吸附构型和最大化发挥单个非极性油分子的作用效能来强化非极性油在低阶煤表面的吸附铺展性能。通过对低阶煤表面润湿性选择性调控，在浮选精煤产率与灰分基本不变的情况下，可较大幅度降低捕收剂用量。采用分子动力学方法研究并阐明了表面活性剂-水-固体表面体系和烃类油捕收剂-水-固体表面体系微观吸附机理，建立非离子表面活性剂-水-固体表面体系和非极性烃类油捕收剂-水-固体表面体系微观吸附行为与宏观现象之间的联系。基于低阶煤中有机质和矿物质表面润湿性差异调控，研究了具有醚基、羧基、酯基、醇羟基等不同类型含氧基团的极性药剂与正十二烷复配捕收剂对低阶煤的浮选增效行为并探讨了其内在机理，探究了极性捕收剂的构效关系并得到了极性捕收剂的筛选标准，发现以浮选完善指标作为低阶煤浮选性能的评价标准时，分子极性指数在6.5~8.0 kcal/mol范围内的含氧极性油类捕收剂可以较好的强化低阶煤的可浮性。项目研究结果阐明了基于低阶煤中有机质与矿物质表面润湿性差异调控来促进其浮选有效分离的机制，为低阶煤高效浮选分选技术的发展提供了基础。