流体剪切对难浮炼焦煤表面疏水性的活化效应及机理

The high efficiency separation of difficult-to-float coking coal is a research hotspot in the field of flotation. High intensity conditioning is an important way of improving the flotation performance of difficult-to-float coking coal. Due to the complex factors affecting the high intensity conditioning, the study on the fluid shear activation for surface hydrophobicity of the coal particles affecting the high intensity conditioning effect has been rare, which limits the deep understanding of the high intensity conditioning mechanism. This project will study the activation mechanism of fluid shear on the hydrophobicity of coal surface from the aspects of the influence of fluid shear on the physical and chemical properties of coal surface and the microscopic changes between solid-liquid interface. The film flotation technique and flotation test will be used to study the activation effect of fluid shear on the hydrophobicity of coal surface, and the effect of activation of surface hydrophobicity on the floatability will be ascertained. Photoelectron spectroscopy and other instruments will be utilized to study the changes of oxygen-containing functional groups, surface morphology and charge characteristics on coal surface, revealing the effect of fluid shear on the physical and chemical properties of coal surface. The formation of active microbubbles on coal surface under shear force field and its effect on particle-bubble adhesion behavior will be investigated by means of cryo-scanning electron microscopy, induction timer and high speed dynamic camera system. The changes of wettability of collectors on coal surface will be studied by Washburn dynamic method. By conducting the aforementioned works, the action mechanism of fluid shear on microscopic changes between the solid-liquid interface will be revealed. The research results are of great significance for the efficient recovery of difficult-to-float coking coal resources.

难浮炼焦煤高效分选是浮选领域的研究热点之一，高强度调浆是改善难浮炼焦煤浮选的重要途径。受高强度调浆影响因素复杂制约，迄今对影响高强度调浆效果的流体剪切活化煤粒表面疏水性的研究比较薄弱，限制了对高强度调浆机理的深刻认识。项目从流体剪切对煤表面物理化学性质的影响和固液界面微观变化两个方面，研究流体剪切对煤表面疏水性的活化机制。通过表层浮选技术及浮选试验研究流体剪切对煤表面疏水性的活化效应，查明表面疏水活化对可浮性的改善作用。采用光电子能谱等研究煤表面含氧官能团、表面形貌及荷电特性等性质的变化，揭示流体剪切对煤表面物理化学性质的影响；借助冷冻扫描电镜、诱导时间仪和高速动态摄像系统探索剪切力场下煤表面活性微泡的生成规律及其对颗粒-气泡黏附行为的影响；并利用Washburn动态法研究捕收剂在煤表面的润湿性变化，揭示流体剪切对固液界面微观变化的作用机制。研究结果对难浮炼焦煤资源的高效回收具有重要意义。

项目以难浮炼焦煤为研究对象，从流体剪切对煤表面物理化学性质的影响和固液界面微观变化两个方面，研究了流体剪切对难浮炼焦煤表面疏水性的活化机制。通过特殊浮选流程设计，研究了流体剪切强度和剪切时间对粗粒和细粒浮选效果的影响，查明了表面疏水活化对可浮性的改善作用，发现了细粒和粗粒所需流体剪切条件的不相容性。提出将高强度调浆过程中表面清洗、药剂分散和颗粒-药剂碰撞分步实施以降低高强度调浆能耗技术设想。通过Zeta电位、扫描电镜与光学显微镜研究了流体剪切对煤粒表面电性和表面形貌的影响。通过气泡负载量和接触角测量考察了流体剪切对煤粒表面疏水性的影响。揭示了流体剪切对煤表面物理化学性质的影响，发现流体剪切可以清除煤粒表面细泥杂质，大幅提高煤的表面疏水性，对粗粒活化作用更明显。利用光学显微镜、高速动态摄像系统和Zeta电位仪研究了不同剪切条件对不同粒度煤固液界面气泡生成规律的影响，探索了不同粒度煤表面黏附气泡的数量和尺寸特征。发现不同粒级煤表面均可生成气泡，气泡数量随煤的粒度增大而增加。气泡多以气泡—颗粒絮团形式存在。增加了煤粒的表观尺寸，有利于改善浮选。推进式桨在各粒级煤的表面均可产生数量可观且直径较小的气泡。