Basic And Applied Research On Extracting Rare Earth Of Large Phase Ratio From Diluent Solution

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 leaching liquid of ion-absorption rare earth ore.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 cavity 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 earth 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 concentration of extractant are studied systematically through the extraction experiment in which Er3+ is extracted by 2-ethyl-hexyl-phosphonic acid mono-(2-ethylhexyI)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 summarized.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.