With enormous interfacial area for particle collection, microbubbles exhibit great application prospect in the mineral flotation. Under certain ionic strength, microbubbles can be produced continuously in the microbubble column without extra reagent addition. In this work, multiphase flow characteristics (Sauter mean diameter, bubble size distribution, gas holdup & interfacial area) were studied systematically with variables including the salt type, salt concentration, and operating conditions. Based on mathematical model, critical coalescence concentration was determined for each investigated salt. According to experimental results, a mathematical correlation was established between the Sauter mean diameter and ionic strength. For the formation of microbubble system, the lowest ionic strength was approximately 0.5 mol/L. Multiphase flow characteristics in the microbubble column depended highly on the ionic strength. The interfacial area and gas holdup increased by 38 times and more than 3 times respectively, with the ionic strength of Al₂(SO₄)₃ rising from 0 to 1.5 mol/L. The critical coalescence concentration ranged from 0.037 mol/L (Al₂(SO₄)₃) to 0.517 mol/L (NaCl), which correlated with the ionic strength of each salt.

中文翻译：

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无机盐对微泡柱中多相流动特性的影响：关注离子强度

微泡具有巨大的颗粒收集界面面积，在矿物浮选中具有广阔的应用前景。在一定的离子强度下，微泡柱内可连续产生微泡，无需额外添加试剂。在这项工作中，系统地研究了多相流特性（Sauter 平均直径、气泡尺寸分布、气体滞留率和界面面积），变量包括盐类型、盐浓度和操作条件。基于数学模型，确定了每种研究盐的临界聚结浓度。根据实验结果，建立了 Sauter 平均直径和离子强度之间的数学相关性。对于微泡体系的形成，最低离子强度约为 0.5 mol/L。微泡柱中的多相流动特性高度依赖于离子强度。随着Al离子强度的增加，界面面积和气体持气率分别增加了38倍和3倍以上₂ (SO ₄ ) ₃从 0 上升到 1.5 mol/L。临界聚结浓度范围为 0.037 mol/L (Al ₂ (SO ₄ ) ₃ ) 到 0.517 mol/L (NaCl)，这与每种盐​​的离子强度相关。