Knowledge Management System Of Institute of process engineering,CAS
萃取技术在冶金行业应用广泛，但是，传统萃取设备不适用于从稀溶液中分离和富集目标组分。本论文采用大相比萃取法从稀溶液中分离和富集目标组分。大相比是将萃取剂以“油泡”的形式分散后实现的。“油泡”是一种核-壳结构，气体构成“油泡”的核，萃取剂构成“油泡”的壳。在核壳结构中作为壳的萃取剂，体积小，但是与萃取液的接触面积大。“油泡”在萃取液中上升时，目标组分从萃取液中传质到“油泡”表面实现萃取。本论文以稀土离子-萃取剂作为模型体系，采用大相比萃取方法萃取稀土离子，主要的研究内容包括：以稀土离子La3+、Er3+作为代表性目标组分，以本论文发明的分布器为模型设备，对大相比萃取稀土离子进行了研究。对通气速率、通油速率以及气油比影响Er3+的萃取进行了研究。发现了通气速率、通油速率影响“油泡”萃取的规律；计算了“油泡”萃取时的体积传质系数。在萃取是一种界面行为的理论指导下，探讨了大相比萃取用于分离富集目标组分的机制。研究结果表明，稀土离子可以通过大相比萃取的方式从稀溶液中实现富集和分离。在本论文发明的恒界面池内对“油泡”萃取的本征动力学进行了研究。采用CFD模拟了在恒界面池内萃取液与萃取剂的流动状况。在实验中系统地研究了流动速度、界面面积、酸碱度以及萃取剂浓度对Er3+萃取速率的影响。CFD的结果表明，萃取剂和萃取液在本论文发明的恒界面池内的流动符合恒界面池测定动力学的要求。实验结果表明，Er3+被P507-煤油萃取时符合拟一级动力学方程，并给出了萃取速率方程。研究了模型设备内“油泡”稳定生成的条件。实验结果表明，内外管顶端的高度差、环隙宽度和操作条件共同影响“油泡”的稳定生成。环隙宽度小（0.17~0.22 mm），套嵌圆管内外管的高度差（-2~48 mm）对形成“油泡”无明显影响。套嵌圆管内外管的高度差-2~6 mm时，环隙宽度在（0.17~0.365 mm）的范围内，对形成“油泡”无明显影响。总结了套嵌圆管的结构参数和操作条件对“油泡”稳定生成的规律。对目标组分从稀溶液中的萃取强化进行了研究。研究结果表明，单位横截面积的萃取柱内，套嵌圆管数目、气体流速、萃取剂流速对“油泡”萃取速率有不同程度的影响。在分布器能够将萃取剂分散成“油泡”的所有萃取剂流速范围内，萃取速率随通气速率的增加而增加。通气速率相同时，通油速率的增加不能显著的影响萃取速率。论文提出了大相比萃取设备的强化规律：气体在萃取柱横截面内的流动速率为0.08 cm/s，通气速率与通油速率的比值约为300:1，单个套嵌圆管所占的萃取柱横截面积为12.7 cm2。;Liquid–liquid extraction is the core technology and widely used in the hydrometallurgical industry. However, traditional extractors can not be used to extract target component from diluent solution. Extraction featured large phase ratio is suggested and used to separate and enrich target component from diluent solution in the dissertation. The large phase ratio is realized by dispersing the extractant into organic bubble. The organic bubble is a core-shell structure, in which the core is composed of gas phase and the shell is a thin layer of extractant. The volume of the extractant is small but the interface between extractant and diluent solution is as large as the surface area of organic bubble.Target component transfers to the extractant from diluent solution during floatation of extractang bubble. In the model system of rare eath ions and extractant, rare earth ions are extracted by solvent extraction featured large phase ratio. The research contents include mainly:La3+, Er3+ as the representative rare earth ions are extracted with large phase ratio in the model device, which is invented in the dissertation. And the research contents include the effects on the extraction rate of flow rates of extractant and gas phase. The volume mass transfer coefficient is calculated. The mechanism of extraction featured large phase ratio for separation and enrichment of target components is discussed. The results indicate that target components can be enriched by extraction featured large phase ratio.The extraction intrinsic kinetics of organic bubble is studied in constant interfacial area cell, which is designed in the dissertation. The flow states and velocity profiles in the cell are simulated by CFD method. The flow rates of two phases, the interfacial area, acidity and the concentraion of extractant are studied systematically through the extraction experiment in which Er3+ is extracted by 2-ethyl-hexyl-phosphonic acid mono-(2-ethylhexyl) ester.The results of CFD indicate that the flow situation meets the requirements in the constant interfacial cell. And the results of the experiment indicate that the extraction rate for Er3+ match pseudo first order kinetics. And the extraction rate equation of Er3+ extracted by 2-ethyl-hexyl-phosphonic acid mono-(2-ethylhexyl) ester is deduced.The key factors for the formation of organic bubble are studied under the large phase ratio. The results indicate that the difference between the height of inner tube and outer tube, the width of gap between two tubes and operating conditions play important role during the formation of extractant bubble. The height of inner tube and outer tube, the width of the gap between the inner tube and the outer tube and operation conditions determine whether the extractant can be dispersed into organic bubble jointly. The difference between the height of inner tube and outer tube from -2 mm to 48 mm has no effect on the formation of organic bubble when the gap is from 0.17 to 0.22 mm. The width of the gap between inner tube and outer tube from 0.17 mm to 0.365 mm has no effect on the formation of organic bubble when the difference between the height of inner tube and outer tube is from -2 mm to 6 mm. Effects on organic bubble formation of structural factors and operating conditions are summerized.The intensification about extraction featured large phase ratio is studied in the model device. The result indicates that the number of pairs of nested tubes, flow rates of gas phase and extractant per unit cross sectional area affect extraction rate with different degree in the model device. In the flow rate range of extractant under the condition of organic bubble formation, the extraction rate increases with the increase of flow rate of gas phase. With the same flow rate of gas phase, the increase of flow rate of extractant can not significantly affect the extraction rate. The intensification criteria are summarized that the velocity of gas phase in the whole cross sectional area is 0.08 cm/s, the flow ratio between gas phase and extractant is about 300:1, and the cross section area of extraction column with one pair of nested tubes is 12.7 cm2.
|肖传绪. 低浓度稀土溶液大相比萃取富集的应用基础研究[D]. 中国科学院研究生院,2018.|
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