Abstract Froth stability is one of the most important factors in fine coal flotation as it significantly affects the separation efficiency. Diesel is always used as the flotation collector while the effect of diesel on the froth stability is less investigated. In this study, effect of diesel on the froth stability and its antifoam mechanism in fine coal flotation used MIBC as the frother was investigated. Three-phase and two-phase froth stability tests were first carried out and the negative effect of diesel on froth stability was further explained by the single foam film drainage and spreading pressure experiments. The results of the three-phase dynamic froth stability showed that the maximum froth height and half-life of froth first increased and then decreased with the increase in diesel concentration. When diesel concentration increased to 8 kg/t, the maximum froth height and half-life of froth increased to 7.7 cm and 19 s. Deforming effect was observed when further increasing diesel dosage. Two-phase froth stability tests showed that the foaming ability and foam stability gradually decreased as the diesel concentration increased. When the diesel concentration increased from 0 to 20 and 40 ppm, the foam half-life decreased from 19 to 2.84 and 1.42 s, respectively. Single foam drainage tests showed that the diesel droplets dispersed into the middle of the foam film resulting in the formation of oil-bridge and rupture of the foam film. Meanwhile, the oil-film spreading pressure was found increased as the diesel concentration increased, directly indicating the antifoam effect of diesel. MIBC molecules were competitively adsorbed at diesel droplets, which reduced the effective concentration of the frother at the gas-water interface. Throughout this study, a certain defoaming effect of diesel on the froth stability in coal flotation was identified.

中文翻译：

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以MIBC为起泡剂的细煤浮选柴油对泡沫稳定性的影响及其消泡机理

摘要 泡沫稳定性是粉煤浮选中最重要的因素之一，它显着影响分离效率。柴油通常用作浮选捕收剂，而柴油对泡沫稳定性的影响研究较少。在这项研究中，柴油对泡沫稳定性的影响及其在使用 MIBC 作为起泡剂的细煤浮选中的消泡机制进行了研究。首先进行了三相和两相泡沫稳定性试验，并通过单泡沫膜排水和铺展压力试验进一步解释了柴油对泡沫稳定性的负面影响。三相动态泡沫稳定性的结果表明，随着柴油浓度的增加，泡沫的最大高度和半衰期先增加后减小。当柴油浓度增加到 8 kg/t 时，最大泡沫高度和泡沫的半衰期增加到 7.7 cm 和 19 s。当进一步增加柴油剂量时观察到变形效应。两相泡沫稳定性试验表明，随着柴油浓度的增加，发泡能力和泡沫稳定性逐渐降低。当柴油浓度从 0 增加到 20 和 40 ppm 时，泡沫半衰期分别从 19 秒减少到 2.84 和 1.42 秒。单次泡沫排水试验表明，柴油液滴分散到泡沫膜中间，导致形成油桥和泡沫膜破裂。同时，发现油膜铺展压力随着柴油浓度的增加而增加，直接表明柴油的消泡效果。MIBC 分子竞争性地吸附在柴油液滴上，这降低了气-水界面处起泡剂的有效浓度。在整个研究中，确定了柴油对煤浮选泡沫稳定性的一定消泡作用。