Experimental research on the interaction behavior between particle and bubble in flotation on a micro⁃nano scale
ZHANG Fanfan,CAO Yijun,XING Yaowen,GUI Xiahui,SUN Lijuan,YANG Haichang,LI Ming
充分了解浮选颗粒与气泡间相互作用过程,有助于指导浮选实际生产过程中表面活性剂的 选择与气-液-固三相界面的调控。 通过表面改性得到亲/疏水颗粒和固体基底,利用先进手段研 究了气泡颗粒间微纳尺度下相互作用过程。 结果表明:亲水颗粒包覆角仅能达到 28.38°,疏水颗粒 包覆角则随时间不断增加,900 s 时可达到 168.55°,说明提高颗粒疏水性可改善其可浮性。 在相对 运动方面,亲水颗粒在气泡表面滑移过程中,颗粒与气泡中心距离保持不变;疏水颗粒在气泡表面 滑移过程中,出现瞬间“下陷”现象,此时颗粒气泡间液膜薄化破裂,推算出破裂液膜厚度约为 0.01 mm。 在相互作用力方面,气泡与亲水表面间不存在黏附引力,由斥力主导;气泡与疏水表面 间出现“跳入” 引力达到 45.80 μN,在接触瞬间液膜薄化破裂,破裂液膜厚度约为 0.02 mm ( ~15.16 μm)。 AFM 测试得到疏水颗粒与微米气泡间液膜破裂厚度为 114.34 nm,此数值较颗粒 与毫米级气泡间破裂液膜厚度相差 2 个数量级,说明颗粒气泡发生黏附作用时,破裂液膜厚度与气 泡尺寸有关。
A full understanding of the interaction process between particles and bubbles is helpful to guide the selection of surfactants and the regulation of gas⁃liquid⁃solid three⁃phase interface in practical flotation. In this paper,hydrophilic/ hydrophobic particles and solid substrates were prepared by surface modification,and the interac⁃ tion between bubbles and particles was studied by some advanced means on a micro⁃nano scale. The results show that the coating angle of hydrophilic particles is only 28.38°,but that of hydrophobic particles can reach to 168.55° at 900 s,indicating that the floatability of particles increase with the improvement of hydrophobicity. In terms of the relative motion,the center distance between the hydrophilic particle and the bubble remains unchanged dur⁃ ing the sliding process of the hydrophilic particle on the bubble surface. In contrary, the hydrophobic particles suddenly " jump in" the bubble surface during the sliding process,the liquid film between the particle and the bubble becomes thin and ruptured at this time. The thickness of the rupture liquid film is about 0.01 mm. In terms of interaction force,the adhesion force is not found between the bubble and the hydrophilic surface,which is dominated by re⁃ pulsion. The obvious “jump-in” attachment force between the bubble and the hydrophobic surface is up to 45.80 μN, and the liquid film is thinning during approaching and breaks suddenly at the moment of contact,the thickness of the rupture liquid film is about 0.02 mm (~15.16 μm). AFM results show that the thickness of liquid film between hy⁃ drophobic particle and micro bubble is 114.34 nm,which is 2 orders of magnitude less than that between particles and millimeter bubbles. It indicates that the thickness of rupture liquid film is related to the size of bubble when parti⁃ cles adhere to bubbles.
particle; bubble; interaction; “jump in” attachment; thickness of rupture fluid film
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会