颗粒气泡黏附科学——宏观尺度下颗粒气泡黏附研究进展及困境

颗粒气泡黏附指从颗粒与气泡相遇开始到液膜发生薄化破裂最后至三相润湿周边铺展形成稳定矿化气絮体的过程，是浮选中的核心作用单元。然而浮选颗粒气泡黏附机理至今仍不明确。黏附过程主要受颗粒气泡的表面物理化学性质及溶液化学条件影响，表面力及流体作用力协同支配微纳尺度下颗粒气泡间液膜薄化破裂行为。排液过程中气液界面的变形效应进一步增加了系统复杂性，上述因素使得颗粒气泡黏附的理论研究及试验探索步履维艰。早期关于颗粒气泡黏附的研究主要聚焦于黏附概率，其中宏观尺度下的诱导时间测试占据主导地位，通过诱导时间结果计算黏附概率。对国内外宏观尺度下颗粒气泡黏附概率模型及研究技术手段进展展开全面综述，并对现有技术瓶颈及局限进行分析。诱导时间测量仪及高速动态摄影技术大大促进了浮选工作者对颗粒气泡黏附的理解，“诱导时间与实际浮选回收率具有着良好的相关关系”也已经被广泛证明。然而因微纳尺度下的表面力及液膜薄化动力学信息的缺失导致宏观诱导时间并不能从基础层面揭示颗粒气泡的黏附机理，微纳尺度下颗粒气泡间相互作用力及液膜薄化动力学的定量测试表征是技术发展的必然趋势，其可为浮选微观矿化反应过程提供新的理论视角，同时也为难浮煤及难选矿浮选过程强化提供理论支撑。

Bubble particle attachment science:Advances and dilemma in bubble particle attachment on a macroscopic scale

Bubble particle attachment is defined as the processes of film thinning and rupture from bubble particle encounter,three phased contact line spreading and the formation of a stable mineralized gas floc,which is the key process in flotation.However,the underlying mechanism for bubble particle attachment is not well understood.The attachment process is mainly influenced by the physical and chemical properties of particle and bubble,and the chemical conditions of the solution.The thinning rupture behavior of the thin liquid film between bubble and particle is controlled by the synergistic effect between surface force and hydrodynamic force.The deformation of gas liquid interface further increases the complexity of the system,making the theoretical research and experimental exploration on bubble particle attachment challenging.Early researches on attachment have been mainly focused on attachment probability.The induction time test on a macroscopic scale is the dominant and the attachment probability can be calculated based on induction time result.A comprehensive review on the current bubble particle attachment probability models and the existing technical bottlenecks was carried out.The existing technical bottlenecks and limitations were also analyzed.Experimental techniques such as the induction timer and high speed visualization have significantly contributed to a better understanding of bubble particle attachment.It has been demonstrated that the induction time correlates well with flotation recovery.However,surface forces and film drainage information between bubble and particle could not be identified,leading to the fundamental adhesion mechanism could not be revealed by macroscopic induction time.It is an inevitable trend of the development of technology to measure the interaction force between bubble and particle and the thinning dynamics of the thin liquid film on a nanometer scale.It can shed new light on flotation micro mineralization process,and also provide a theoretical support for the flotation intensification of difficult to float coal and refractory ore.