浮选颗粒−气泡湍流脱附机理与试验技术方法研究进展

Advances in theoretical and experimental methods of bubble-particle turbulent detachment in flotation

  • 摘要: 浮选是细粒矿物及煤炭提质除杂的重要方法,但其分选过程存在明显的尺寸效应,其中湍流诱发颗粒−气泡脱附是导致浮选存在分选粒度上限的主要原因。为了提高浮选粒度上限,强化粗粒浮选效果,颗粒−气泡脱附研究一直是领域内的热点与难点。从颗粒−气泡准静态脱附理论、湍流脱附机制以及试验技术方法3个方面对颗粒−气泡脱附研究现状进行了系统综述。目前颗粒−气泡法向脱附机理已经形成广泛共识,毛细力是维持颗粒−气泡矿化气絮体稳定的主要作用力,颗粒−气泡脱附可分为气泡拉伸变形、气泡滑动收缩及气泡颈缩断裂3个阶段。同时,颗粒−气泡湍流脱附机制认识已日趋系统,颗粒的离心运动、气泡的变速运动以及气泡的振荡是引起颗粒−气泡脱附的主要机制。此外,脱附力测试技术、高速动态摄像技术、粒子图像测速技术及数值模拟等试验方法的综合运用,形成了一个涵盖“脱附力测试、界面行为捕捉、流场解析和过程仿真”的综合研究体系,极大地推动了颗粒−气泡脱附研究向更微观、更深层次的方向发展,为揭示浮选颗粒−气泡湍流脱附机理提供了充足可靠的试验保障。最后提出了未来颗粒−气泡脱附研究的发展方向,包括不同分离角度下毛细力数学模型构建、湍流诱发颗粒−气泡脱附能量作用机制及多元湍流涡协同诱导多颗粒−气泡脱附机制研究。上述关键科学问题的解决不仅有助于完善脱附理论,还将对提高浮选粒度上限和强化粗颗粒浮选具有重要指导意义。

     

    Abstract: Flotation is an effective method to improve the quality of fine minerals and coal, but the separation process exhibits significant size effects. The bubble-particle detachment caused by turbulence is the main reason for the upper limit of separation particle size in flotation. To increase the upper limit of flotation size and enhance the flotation effect of coarse particles, the study of bubble-particle detachment has always been a hot and difficult point in the field. The research status of bubble-particle detachment is reviewed from three aspects: quasi-static detachment theory, turbulent detachment mechanism and experimental methods. There is now a broad consensus on the normal detachment mechanism of bubble-particle aggregates, where capillary force is the main force maintaining the stability of the bubble-particle mineralized aggregates. Bubble-particle detachment can be divided into three stages: bubble stretching process, bubble sliding process, and bubble necking process. Moreover, understanding of the bubble-particle turbulence detachment mechanism has become more systematic, with centrifugal motion of particles, variable-speed motion of bubbles, and bubble oscillation being key factors leading to detachment. In addition, the comprehensive application of experimental methods such as detachment force testing technology, high-speed dynamic photography technology, particle image velocity measurement technology and numerical simulation has created a comprehensive research framework encompassing “detachment force testing, interface behavior capture, flow field analysis, and process simulation”. This comprehensive approach has greatly promoted the development of bubble-particle detachment research to a more microscopic and deeper direction, and provided sufficient and reliable experimental guarantee for revealing the bubble-particle turbulent detachment. Finally, the development direction of bubble-particle detachment research in the future is proposed, including the construction of capillary force mathematical model under different separation angles, the mechanism of bubble-particle detachment energy induced by turbulence, and the study of multi-bubble-particle detachment mechanisms induced by multi-scale turbulent vortices. Solving these key scientific problems will not only improve detachment theory but also provide important guidance for increasing the flotation size limit and enhancing coarse particle flotation performance.

     

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