Froth flotation, a versatile particle separation technology, is widely used for beneficiation of minerals. Central to the flotation process is the bubble-particle interaction. Recent research progress showed that flotation efficiency could be improved by acoustic sound, which was attributed to increased froth stability, but it was not clear as to whether the acoustic sound would also enhance the bubble-particle interaction. To fill this gap of knowledge, this paper explores the effect of acoustic sound on the stability of thin water film confined between an air bubble and a flat quartz substrate. The film lifetimes were measured by analyzing the optical images of the films recorded. The study considered three variables: sound frequency (in the range of 0.5–20 kHz), substrate hydrophobicity (with contact angle ranging from less than 5° to about 35°) and bubble size (0.7, 1.1, 1.4 and 1.7 mm). For any substrate hydrophobicity and bubble size tested, use of acoustic sound at frequencies of 3–20 kHz while keeping the same sound amplitude (88 ± 3 dB) would decrease the film lifetime, in favor of flotation; in contrast, mixed trends were observed at frequencies of 0.5–2 kHz, reflecting the complexity of the system. With or without the sound, the film lifetime would decrease with increasing substrate hydrophobicity or decreasing bubble size. The present work provides new insights into improvement of flotation with acoustic sound.

中文翻译：

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气泡和石英表面之间形成的薄膜水膜的稳定性

泡沫浮选是一种多功能的颗粒分离技术，广泛用于矿物选矿。浮选过程的核心是气泡与颗粒的相互作用。最近的研究进展表明，声波可以提高浮选效率，这归因于泡沫稳定性的增加，但尚不清楚声波是否也会增强气泡与颗粒的相互作用。为了填补这一知识空白，本文探讨了声学声音对限制在气泡和平坦石英基板之间的薄水膜稳定性的影响。通过分析记录的薄膜的光学图像来测量薄膜的寿命。该研究考虑了三个变量：声音频率（0.5-20 kHz范围内）、基材疏水性（接触角范围从小于5°到约35°）和气泡尺寸（0.7、1.1、1.4和1.7毫米）。对于任何测试的基材疏水性和气泡尺寸，使用频率为 3-20 kHz 的声波同时保持相同的声幅 (88 ± 3 dB) 将缩短薄膜寿命，有利于浮选；相反，在 0.5-2 kHz 频率处观察到混合趋势，反映了系统的复杂性。无论有或没有声音，薄膜的寿命都会随着基材疏水性的增加或气泡尺寸的减小而缩短。目前的工作为利用声学声音改进浮选提供了新的见解。