Gemini微乳捕收剂的制备及对低阶难浮煤泥的表面改性机理和浮选性能研究

Low-rank coal slime is featured by a number of oxygen-containing functional groups on surface, strong hydrophilicity and low floatability, and conventional hydrocarbon oil collector has the drawback of poor dispersion. In order to address these issues, this project is proposed to construct model compounds that correspond to different coal surfaces by means of characterizing properties of oxygen-containing functional groups deposited on the coal surface. Then the surface of low-rank difficult-to-float coal slime will be modified for improving surface hydrophobicity by Gemini surfactants. The interaction between Gemini surfactants and surface of low-rank coal will be studied by simulation of molecular kinetics, thereby revealing the mechanism of surfactant modification on the surface of low rank coal at molecular level. This project will propose technical prototype of surface modification of low rank coal and structural model of surfactant, which provides fundamental theory to the design of surfactant. Furthermore, non-ionic Gemini surfactants will be synthesized via addition reaction of ethylene oxide condensate. The hydrocarbon oil will be dispersed into nano-scale oil droplets by PIT microemulsion. As a result, Gemini microemulsified collector characterized by low dosage, high dispersion and nano diameter will be prepared. In addition, the flotation performance of Gemini microemulsified collector will be investigated to probe its surface adsorption modification and flotation mechanism from both macroscopic and microscopic views. The objective of this proposed project is to develop Gemini microemulsified collector for low-rank coal. This study will improve the surface hydrophobicity of low-rank difficult-to-float coal slime and poor dispersion of convertional hydrocarbon oil collector,and increase the flotation efficiency , and enrich fundamental theory for the development of coal collector. Therefore, it will greatly promote the effective exploitation and utilization of low rank coal resources in China.

本项目针对低阶煤泥表面含氧官能团多、亲水性强、可浮性差的特点以及传统烃油捕收剂分散性差的缺陷，拟从低阶煤泥表面性质入手，表征其表面含氧官能团的赋存特征，据此构建符合不同煤阶煤表面特点的模型化合物；拟采用Gemini表面活性剂对低阶煤泥进行表面改性提高其疏水性，通过分子动力学模拟，从分子层面揭示Gemini表面活性剂对低阶煤表面的改性机理，提出低阶煤表面改性的技术原型和表面活性剂原则结构模型；然后，采用缩合-环氧乙烷加成反应合成Gemini表面活性剂，并以其为核心乳化剂，利用PIT微乳化法将烃油分散为纳米级油滴，制备出"低用量、高分散性、纳米粒径"的Gemini微乳捕收剂；进而，开展Gemini微乳捕收剂浮选性能研究，揭示其表面吸附改性特征和浮选机理。本项目通过研制符合低阶煤泥特点的Gemini微乳捕收剂，旨在高效改善低阶煤泥表面疏水性和烃油捕收剂分散性，提高浮选效率，促进我国低阶煤的开发。

针对低阶煤泥表面含氧官能团多、亲水性强、可浮性差的特点以及传统烃油捕收剂分散性差的缺陷，制备了“低用量、高分散性、纳米粒径”的微乳捕收剂。以神东低阶煤泥为研究对象，查明了微乳捕收剂对低阶煤泥的浮选性能，获得了最佳浮选药剂制度；采用分子模拟和试验研究相结合的方法，阐明了微乳捕收剂，尤其是Gemini表面活性剂在低阶煤表面的吸附改性机理，从分子层面揭示了其对低阶煤润湿性的微观调控机制，为低阶煤的高效提质利用提供了理论依据和技术支持。.合成了具有高表面活性的非离子型Gemini表面活性剂，以此为核心乳化剂，通过拟三元相图法、电导法、响应面法及相转变温度法，对微乳捕收剂的配方进行设计优化，获得了Gemini表面活性剂、正戊醇、0#柴油和水的最佳比例，为18.25∶18.25∶35.50∶28.00，微乳捕收剂为水包油型，平均粒径为29.30nm，放置8个月后仍保持稳定状态。.低阶煤泥浮选实验表明，微乳捕收剂在用量2.0 kg·t-1，起泡剂用量0.17 kg·t-1时，获得最佳浮选指标，浮选行为符合二级浮选动力学模型，与传统烃油捕收剂（0#柴油）相比，在精煤灰分相近的前提下，微乳捕收剂的精煤产率增加了36.24%、可燃体回收率提高了36.54%，捕收剂用量节省了66.67%，起泡剂用量节省了71.67%。.Gemini表面活性剂在低阶煤泥表面的吸附符合Langmuir等温吸附模型，吸附过程为自发进行、氢键作用为主的物理吸附，符合准二级动力学方程。Gemini表面活性剂的浓度为0.20 g·L-1时，吸附后低阶煤的接触角达到最大值，比原煤的接触角增加了近13°。与适量的表面活性剂作用后，低阶煤的表面自由能降低，碳、氧元素的含量比值增大，含氧官能团含量明显减少，提高了低阶煤泥的疏水性。.分子动力学模拟研究表明，Gemini表面活性剂与低阶煤表面的极性基团发生吸附，以氢键作用为主，非极性碳链高度缠绕在一起，指向体相水。低阶煤表面吸附Gemini表面活性剂后，体系更加稳定，与水的结合能力明显减弱，体系中水分子的扩散运动显著增强，说明吸附表面活性剂后低阶煤的疏水性得到有效的改善，与吸附特性和润湿性能研究的结论一致。