混合表面活性剂强化低阶煤浮选泡沫稳定性机理研究.pdf

硕士学位论文 混合表面活性剂强化低阶煤浮选泡沫稳定 性机理研究 Study on Foam Stability Mechanism of Low Rank Coal Flotation Enhanced by Mixed Surfactant 作者郭芳余 导师李国胜 副教授 中国矿业大学 二〇二一年四月 万方数据 学位论文使用授权声明学位论文使用授权声明 本人完全了解中国矿业大学有关保留、使用学位论文的规定，同意本人所撰 写的学位论文的使用授权按照学校的管理规定处理 作为申请学位的条件之一， 学位论文著作权拥有者须授权所在学校拥有学位 论文的部分使用权，即①学校档案馆和图书馆有权保留学位论文的纸质版和电 子版，可以使用影印、缩印或扫描等复制手段保存和汇编学位论文；②为教学和 科研目的，学校档案馆和图书馆可以将公开的学位论文作为资料在档案馆、图书 馆等场所或在校园网上供校内师生阅读、浏览。另外，根据有关法规，同意中国 国家图书馆保存研究生学位论文。 （保密的学位论文在解密后适用本授权书）。 作者签名导师签名 年月日年月日 万方数据 中图分类号学校代码10290 UDC密级公开 中国矿业大学 硕士学位论文 混合表面活性剂强化低阶煤浮选泡沫稳定性机理 研究 Study on Foam Stability Mechanism of Low Rank Coal Flotation Enhanced by Mixed Surfactant 作者郭芳余导师李国胜 申请学位工学硕士学位培养单位化工学院 学科专业矿物加工工程研究方向浮选过程强化 答辩委员会主席杨建国评 阅 人 二○二一年四月 万方数据 致谢致谢 时间转瞬即逝，硕士生涯转眼已近尾声。回顾在矿大的点滴，往昔的每分每 秒都历历在目。三年的时光既短暂又漫长，其中充满了酸甜苦辣，更有收获和成 长。在论文完成之际，对给予我帮助和支持的每一个人表达心中最真挚的谢意。 首先，我要感谢我的导师李国胜副教授。李老师严谨的治学态度以及精益求 精的工作作风时刻鼓励着我前行，为我树立了学习的榜样。三年来，从研究方向 的确定、试验的完成到最终的写作，李老师时刻关注并指导着我，也正是在老师 帮助下，我才能在科研道路上不断取得进步。 同时感谢桂夏辉研究员在学术上的指导和生活上的关心。 桂老师渊博的专业 知识和素养令我心向往之。桂老师尽其所能地为我们提供良好的科研环境，给予 学生在学术研究上最大的自由，使学生能发挥自己的特长。在生活上，桂老师对 学生也悉心关照。在此，再次向桂老师表达我最诚挚和衷心的感谢 感谢邢耀文研究员在论文选题、试验设计等方面给予的宝贵意见，邢老师在 学术上的指导总能让我茅塞顿开， 其宽阔的学术视野和活跃的学术思维使我受益 匪浅。感谢徐梦迪讲师在整个课题中为我提供的帮助，当我遇到困难时耐心为我 答疑解惑，一直鼓励支持我，让我不断前进。 感谢刘敏博士、张友飞博士、罗佳倩硕士一路的相伴，和你们一起学习成长 的岁月里留下了很多美好的回忆。感谢夏阳超讲师、杨自立博士、张锐博士、李 明博士、朱春云博士、王军超博士、高尚博士、张凡凡博士、孙丽娟博士等师兄 师姐在学习和生活上提供的帮助。感谢黄露露硕士、何琦硕士、韩宇硕士、司伟 汗硕士、尹青临硕士、王钰赛硕士、刘晓康硕士、赵俊吉硕士、常国慧硕士、郑 茜硕士、张鹏德硕士、何琳硕士、禚鹏程硕士等师弟师妹在试验及数据处理等方 面提供帮助。 感谢丁世豪博士对我无微不至的关怀和陪伴， 和你一起奋斗的时光让我感受 到莫大的欢乐和温暖，让我的生活丰富多彩。 特别感谢呵护我成长的父母。你们永远坚定地站在我身后，默默无闻地奉献 着爱与宽容。十年的在外求学之路，寄托着你们对我的殷切希望，我一定带着你 们的期望，努力工作，快乐生活。 最后，感谢百忙之中评阅本论文的各位专家，由于作者水平有限，论文难免 出现错误和不当之处，敬请不吝赐教。 万方数据 I 摘摘要要 浮选是利用颗粒表面疏水性差异实现煤与矸石的选择性分离， 是细粒煤炭资 源提质利用的重要途径， 其中泡沫的形成与稳定是影响煤泥浮选回收率和选择性 的重要因素。目前煤泥浮选主要采用杂醇类表面活性剂提高泡沫稳定性，研究表 明短链与长链混合表面活性剂稳泡能力强，可获得更高的浮选回收率和选择性， 但其内在泡沫稳定性机理仍未明晰。鉴于此，论文选取三种碳链长度不同的醇类 表面活性剂 （正戊醇； 甲基异丁基甲醇， MIBC； 仲辛醇） 与长链聚乙二醇 （PEG） 按不同质量比进行混合， 探索混合表面活性剂对煤泥浮选效果及三相泡沫稳定性 的影响， 通过研究混合溶液的宏观泡沫稳定性和微观尺度下气泡间液膜排液动力 学，揭示混合表面活性剂强化低阶煤浮选泡沫稳定性机理，为煤泥浮选泡沫稳定 性调控提供技术支持。 研究了单一和混合表面活性剂对煤泥浮选效果的影响。 当表面活性剂用量小 于 500 g/t 时，三种短链醇的精煤产率和浮选速率高于 PEG；随着药剂用量增加 至 1000 g/t，PEG 浮选精煤产率和速率显著高于短链醇。造成该现象的原因可能 是由于 PEG 非极性基碳链长， 在药剂用量较低时， 大量 PEG 分子吸附在煤表面， 使得气泡表面的 PEG 分子数减少，导致对泡沫稳定性调节能力弱，因此浮选产 率较低。混合表面活性剂浮选精煤产率明显高于短链醇低于 PEG，其中正戊醇 和 PEG 混合效果优于 MIBC、仲辛醇，归因于正戊醇和 PEG 混合溶液三相泡沫 稳定性最强。 单一及混合表面活性剂条件下精煤灰分基本不变， 浮选选择性相同。 借助表面张力仪测试了单一和混合表面活性剂溶液的表面张力。 溶液表面张 力随表面活性剂浓度的增加而下降，表面活性从大到小依次为 PEG＞仲辛醇＞ MIBC＞正戊醇。混合表面活性剂体系中，溶液表面张力随着 PEG 组分的增加而 降低，表面张力值显著低于短链醇略大于 PEG，正戊醇和 PEG 混合溶液降低溶 液表面张力的能力最强。利用气泡形态观测系统进行气泡尺寸分布研究，发现去 离子水中大气泡含量较多，表面活性剂的加入使得气泡尺寸减小。抑制气泡兼并 是气泡尺寸减小的主要原因，抑制气泡兼并的能力与表面张力变化规律一致。混 合表面活性剂溶液中气泡尺寸显著小于单一溶液，其中正戊醇和 PEG 混合溶液 抑制气泡兼并的能力最强，因此泡沫稳定性最强，对低阶难浮煤浮选促进效果最 好。通过泡沫稳定性试验装置研究了宏观泡沫稳定性。四种表面活性剂的起泡能 力和稳泡能力按照 PEG、仲辛醇、MIBC、正戊醇顺序递减。三种短链醇和 PEG 混合体系的泡沫稳定性显著强于短链醇弱于 PEG，表明表面活性剂的混合具有 一定的协同效应，且 PEG 性能占主导，其中正戊醇和 PEG 混合溶液泡沫稳定性 最强，MIBC 和 PEG 次之，仲辛醇和 PEG 混合溶液较差，这是导致混合表面活 万方数据 II 性剂下浮选回收率差异的主要原因。 采用浮选液膜分析仪研究了单一和混合表面活性剂体系气泡间液膜排液动 力学。去离子水中气泡间液膜薄化后在中心点处发生破裂，破裂时间为 0.69 s， 临界破裂厚度为 18.65 nm。 表面活性剂加入后可以显著减缓液膜薄化速率，增加 液膜寿命，提高液膜稳定性，均是通过减小体系疏水力来实现。四种表面活性剂 的稳泡能力依次为PEG＞仲辛醇＞MIBC＞正戊醇。混合表面活性剂溶液中液 膜排液速率显著低于短链醇，与 PEG 接近，分析认为主要与混合表面活性剂抑 制疏水引力的能力较强有关。其中正戊醇和 PEG 混合溶液泡沫稳定性最强，这 是由于正戊醇和 PEG 表面活性差最大进而形成的表面张力梯度最大，表面活性 剂分子回流作用强，因此提高了气液界面 Gibbs-Marangoni 效应使得泡沫稳定性 增加。 该论文有图 73 幅，表 10 个，参考文献 96 篇。 关键词关键词浮选；混合表面活性剂；泡沫稳定性；协同效应；液膜排液 万方数据 III Abstract Floatation is an important way to realize selective separation of coal and gangue utilizing the difference of particle surface hydrophobicity. It is an important to improve and utilize fine coal resources. The ation and stability of foam are the important factors that affect the recovery rate and selectivity of coal flotation. At present, it’s common to use fusel surfactants to improve foam stability in coal slime flotation. The study shows that the mix use of short chain and long chain surfactants have strong foam stability, which can achieve better flotation recovery and selectivity, but the intrinsic mechanism of foam stability is not yet clear. In view of this, three kinds of alcohol surfactants with different carbon chain length pentanol, methyl isobutyl carbinol, MIBC, octanol were mixed with long chain polyethylene glycol PEG at different mass ratios to explore the effect of mixed surfactants on the flotation efficiency of slime and the stability of three-phase foam. By studying the macro foam stability of mixed solutions and the kinetics of liquid film drainage at the micro scale, the stability mechanism of mixed surfactants in enhancing flotation froth is revealed, which provides technical support for the regulation of the stability of coal flotation froth. The effects of single and mixed surfactants on the flotation of coal slime were studied. When the dosage of surfactant was less than 500 g /t, the clean coal yield and flotation rate of three short chain alcohols were higher than that of PEG; when the dosage of surfactant increased to 1000 g /t, the clean coal yield and flotation rate of PEG were significantly higher than that of short chain alcohols. The reason for this phenomenon might be due to the long length of non-polar group of PEG. When the PEG’s dosage is low, a large number of PEG molecules adsorbed on the coal surface, resulting in a decrease in the number of PEG molecules on the surface of the bubbles, which weakens the regulation of foam stability, causing a low flotation yield. The floatation yield of clean coal with mixed surfactants was significantly higher than that of short chain alcohols but lower than that of PEG. The effect of mixed use of pentanol and PEG is better than MIBC and octanol, because the stability of three-phase foam in pentanol and PEG mixed solution is the strongest. Under the condition of single surfactant and mixed surfactant, the ash content of clean coal is basically unchanged and the flotation selectivity is the same. The surface tension of single surfactant solution and mixed surfactant solution was measured by means of surface tension meter. The surface tension of the solution 万方数据 IV decreases with the increase of surfactant concentration, and the order of surface activity is PEG octanol MIBC pentanol. In the mixed surfactant system, the surface tension of the solution decreases with the increase of PEG component, and the value of surface tension is significantly lower than that of short chain alcohol and slightly higher than that of PEG. Mixed solutions of pentanol and PEG had the strongest ability to reduce the surface tension of the solution. The bubble size distribution is studied by bubble morphology observation system. It is found that there are more large bubbles in deionized water, and the size of bubbles decreases with the addition of surfactant. Inhibition of bubble coalescence is the main reason for the decrease of bubble size, and the ability to inhibit bubble coalescence is consistent with the variation of surface tension. The size of bubbles in mixed surfactants solution is significantly smaller than that in single solution. The mixed solution of pentanol and PEG inhibits the ability of bubble merging. The stability of foam is the strongest, and the flotation efficiency of low-ra nk hard to float coal is the best. The macro scale foam stability was studied by foam stability test device. The foaming ability and foam stability of the four surfactants decrease in the order of PEG, octanol, MIBC and pentanol. The foam stability of three kinds of short chain alcohol and PEG mixed system is significantly stronger than that of short chain alcohol but weaker than PEG, indicating that the mixing of surfactants has certain synergistic effect, and PEG perance dominates. Among them, the mixed solution of pentanol and PEG has the strongest foam stability, followed by MIBC and PEG, and that of mixed solution of octanol and PEG is poor, which is the main reason of the difference of flotation recovery rate of mixed surfactants. The dynamics of liquid film drainage between bubbles of single surfactant system and mixed surfactant system was studied by flotation foam film analyzer. The foam film between bubbles in deionized water breaks at the central point after thinning in which the breaking time is 0.69 s and the critical breaking thickness is 18.65 nm. The addition of surfactant can significantly slow down the thinning rate of foam film, increase the life and improve the stability of foam film, all of which are realized by reducing the hydrophobic force of the system. The foam stability of the four surfactants was PEG octanol MIBC pentanol. The results show that the liquid film drainage rate of mixed surfactant solution is significantly lower than that of short chain alcohol solution, which is close to that of PEG solution. The mixed solution of PEG and pentanol had the best foam stability. This is because the 万方数据 V maximum surface tension gradient is ed by the maximum difference of the surface activity of pentanol and PEG, and the surfactant reflux is strong. Therefore, the increased Gibbs-Marangoni effect of the solution enhances the foam stability. There are 73 pictures, 10 tables and 96 references in this paper. Keywords flotation; mixed surfactant; foam stability; synergy effect; foam drainage 万方数据 VI 目目录录 摘要摘要................................................................................................................................I 目录目录............................................................................................................................. VI 图清单图清单...........................................................................................................................X 表清单表清单........................................................................................................................XV 变量注释表变量注释表.............................................................................................................. XVI 1 绪论绪论............................................................................................................................1 1.1 研究背景及意义.....................................................................................................1 1.2 泡沫的结构和衰变.................................................................................................1 1.3 表面活性剂强化泡沫稳定性研究进展.................................................................3 1.4 气泡间相互作用研究进展...................................................................................10 1.5 研究内容与技术路线...........................................................................................14 2 试验材料与方法试验材料与方法......................................................................................................16 2.1 药剂与仪器设备...................................................................................................16 2.2 试验方法...............................................................................................................17 2.3 煤样制备与性质分析...........................................................................................20 2.4 本章小结...............................................................................................................25 3 混合表面活性剂强化煤泥浮选试验研究混合表面活性剂强化煤泥浮选试验研究..............................................................27 3.1 试验方法与评价指标...........................................................................................27 3.2 表面活性剂对低阶难浮煤浮选效果的影响.......................................................29 3.3 表面活性剂对三相泡沫稳定性的影响...............................................................36 3.4 本章小结...............................................................................................................38 4 宏观两相泡沫性质及其稳定性宏观两相泡沫性质及其稳定性..............................................................................39 4.1 溶液表面张力变化规律.......................................................................................39 4.2 气泡尺寸分布变化规律.......................................................................................41 4.3 宏观泡沫稳定性研究...........................................................................................49 4.4 本章小结...............................................................................................................52 5 气泡间液膜薄化动力学气泡间液膜薄化动力学..........................................................................................54 5.1 去离子水中气泡间液膜薄化动力学...................................................................54 5.2 单一表面活性剂体系气泡间液膜薄化动力学...................................................55 5.3 混合表面活性剂体系气泡间液膜薄化动力学...................................................62 5.4 本章小结...............................................................................................................70 万方数据 VII 6 结论与展望结论与展望..............................................................................................................72 6.1 主要结论...............................................................................................................72 6.2 主要创新点...........................................................................................................73 6.3 展望.......................................................................................................................73 参考文献参考文献......................................................................................................................75 作者简历作者简历......................................................................................................................82 学位学位论文论文原创性声明原创性声明..................................................................................................83 学位论文数据集学位论文数据集..........................................................................................................84 万方数据 VIII Contents Abstract.......................................................................................................................ⅢⅢ Contents....................................................................................................................VⅢⅢ List of Figures..............................................................................................................X List of Tables.............................................................................................................XV List of Variables.......................................................................................................XVI 1 Introduction...............................................................................................................1 1.1 Research Background and Significances................................................................. 1 1.2 The Structure and Decay of Foam............................................................................1 1.3 Research Progress of Foam Stability Enhancement by Surfactant..........................3 1.4 Research Progress of Interaction between Bubble.................................................10 1.5 Research Content and Technical Route................................................................. 14 2 Experiment Materials and s........