Flotation of coarse particles with poor mineral liberation, aiming at gangue rejection at early stage, has attracted great attentions. Bubble detaching probability ultimately determines the coarse particle separation efficiency. To date, the bubble detaching behavior from the surface of coarse particles with poor liberation remains unclear. In this study, three sizes of bubbles (650 μm, 900 μm and 1200 μm) were generated to comparatively study their sliding behavior on a hydrophilic quartz substrate containing discretely distributed hydrophobic dots with a diameter of 100 µm and an edge distance of 400 µm. It was found that bubbles experienced stretching phase and sliding phase during the process. The initial three-phase contact line before sliding increased over the bubble size, resulting in greater force required to initialize bubble sliding. During the sliding process, the three-phase contact line remained the same for the bubble of 650 μm, while it exhibited a stepwise increase for the bubbles of 900 μm and 1200 μm, indicating that the sliding could stabilize bubble attachment to some extent for larger bubbles by strengthen the adhering force. Further study showed that the enhanced bubble attaching stability was only valid with the Reynolds number below 6222. The finding indicates that bigger bubbles may be able to benefit coarse particle flotation in a tranquil flow by providing stronger lifting force for particle ascending. It is believed that the outcomes of this study could facilitate the optimization of coarse particle flotation.

中文翻译：

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研究气泡在包含离散分布的疏水贴片的亲水表面上的滑动行为


针对早期压矸石脱离的粗颗粒浮选，引起了人们的广泛关注。气泡分离概率最终决定了粗颗粒分离效率。迄今为止，释放较差的粗颗粒表面的气泡分离行为仍不清楚。在这项研究中，产生了三种尺寸的气泡（650 μm、900 μm 和 1200 μm），以比较研究它们在亲水性石英衬底上的滑动行为，该衬底包含直径为 100 μm 且边缘距离为 400 μm 的离散分布疏水点。结果发现，气泡在此过程中经历了拉伸阶段和滑动阶段。滑动前的初始三相接触线在气泡尺寸上增加，导致初始化气泡滑动需要更大的力。在滑动过程中，650 μm 气泡的三相接触线保持不变，而 900 μm 和 1200 μm 气泡的三相接触线呈逐步增加，表明滑动可以通过增强粘附力在一定程度上稳定较大气泡的气泡附着。进一步的研究表明，增强的气泡附着稳定性仅在雷诺数低于 6222 时有效。这一发现表明，更大的气泡可能能够通过为粒子上升提供更强的升力，从而有利于静流中的粗颗粒浮选。相信本研究结果有助于粗颗粒浮选的优化。