Capture of impacting particles on a confined gas–liquid interface
Capture of impacting particles on a confined gas–liquid interface
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DOI：
10.1016/j.mineng.2013.10.001
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发表时间：
2014
影响因子：
4.8
通讯作者：
Dongmei Liu;Qinglin He;G. Evans
中科院分区：
文献类型：
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作者：
Dongmei Liu;Qinglin He;G. Evans
膜浮选高度依赖于在气-液自由表面上想要的和不想要的颗粒分离的程度。可以进行单颗粒实验和建模分析，以确定可能发生最佳分离的临界撞击速度。然而，在商业薄膜浮选系统中，自由表面的较高装载密度可导致改变临界冲击速度的相互作用。为了研究这种影响，膜浮选实验已经进行了4，5和6毫米直径的球形聚丙烯颗粒与水，蔗糖和表面活性剂（CTAB）的解决方案包含在不同的尺寸和润湿性（静态接触角）的容器。实验上观察到，对于给定的颗粒直径，发现临界冲击速度随着容器直径的减小而减小，特别是当颗粒与容器直径比增加超过约0.2时。相反，临界冲击速度被认为是相对独立的液体深度，但在容器壁有影响的区域中，随着静态接触角的减小而减小。实验系统也使用杨拉普拉斯方程建模，使用静态和前进的颗粒和血管表面的接触角测量。该模型的预测一般与实验观察，包括显示在颗粒的穿透深度增加，增加血管直径和弯月面轮廓，无论是在颗粒的冲击点和血管壁的良好协议。当使用前进接触角时，预测得到改善，特别是对于有更多液体运动的较小直径的容器。最后，一个模型，以确定所需的血管的临界（最小）直径，使所产生的碰撞粒子的空腔轮廓是不太可能受到血管壁的影响。
Film flotation is highly dependent upon how well wanted and unwanted particles are separated at the gas–liquid free surface. Single particle experiments and modelling analysis can be undertaken to determine a critical impact velocity at which the optimum separation is likely to occur. However, in commercial film flotation systems the higher loading density of the free surface can result in interactions that change the critical impact velocity. To investigate this influence, film flotation experiments have been undertaken with 4, 5 and 6 mm diameter spherical polypropylene particles with water, sucrose and surfactant (CTAB) solutions contained within vessels of varying dimensions and wettability (static contact angle). Experimentally it was observed that for a given particle diameter the critical impact velocity was found to decrease with decreasing vessel diameter, especially when the particle-to-vessel diameter ratio increased beyond about 0.2. Conversely, the critical impact velocity was found to be relatively independent of the liquid depth; but did decrease with decreasing static contact angle in the region where the vessel wall had an influence. The experimental system was also modelled using the Young–Laplace equation using both static and advancing contact angle measurements for both the particle and vessel surfaces. The model predictions were generally in good agreement with the experimental observations, including showing an increase in particle penetration depth with increasing vessel diameter and meniscus profiles, both at the particle impact point and the wall of the vessel. The predictions were improved when the advancing contact angle was used, especially for the smaller diameter vessels where there was more liquid motion. Finally, a model to determine the critical (minimum) diameter of vessel required so that the cavity profile generated by the impacting particle is unlikely to be influenced by the vessel walls is presented.