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Study on separation and key technology of P507-N235 system without saponification and extraction of

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Tutor: YangYouMing
School: Jiangxi University of Technology
Course: Non-ferrous metallurgy
Keywords: rare earth,unsaponifiable,extraction,P507,N235
CLC: TF845
Type: Master's thesis
Year:  2012
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The solvent extraction,which is already a kid of mature technique, has been widely used toseparate and purify rare earths by most rare earth factories at present in our country. But theextraction system exists now also have some obvious disadvantages. Treating ammonia-nitrogenwaste water also restricted the development of rare-earths industry, and it has dogged the rareearths factories for a long time. A number of unsaponifiable techniques are invented byresearchers in recent years. N235have a strong capability of extracting HCl, based on this feature,we designed P507-N235binary solvent system. The mixed solvent of P507and N235was usedas the organic phase of new extraction system firstly. The P507-N235system can extracts rareearth unsaponifiable directly. The extraction effect of rare earths and the changes of separationfactors in P507-N235system were studied in this article. The effect of stripping and recycle ofthe organic phase was also studied. The experiment obtained good results.The results showed that the extraction effects of rare earths ware fine in P507-N235system,the best ratio of system was P507:N235: kerosene=30:25:45. P507-N235system inherited thefeatures of P507system, the extraction ability of rare-earth elements increased with the atomicnumber in new system. The effect in new P507-N235system can reach about80%of originalsystem so long as the procedure conditions are appropriately controlled.The separation coefficient of La/Ce in P507-N235system was better than that of currentsystem at the same condition. The separation coefficient of La/Ce in P507-N235system increasedwith N235concentration and phase ratio. The results of experiments showed that separationcoefficients of rare-earth elements were generally better than that of current system at the samecondition.Rare-earth elements were easy back extracted in P507-N235system. Simulationexperiments of countercurrent extraction indicated that the optimum processing conditions. Bestconcentration of HCl was5mol/L, The phase ratio was10:2(O/A). Back-extraction efficienciescan reached over98%after5-stage of stripping. At this point, the aqueous phase was high in rareearth concentrations, but low in acidity. The consistence of residual acid in mixed organic wasabout0.8mol/L.The mixed organic with good recycle results as long as the consistence of residual acid inmixed organic controlled below0.1mol/L. To remove the acid in mixed organic by water wasdifficult in experiments. However, the mixed organic with good recycle results when theconsistence of residual acid in mixed organic was low.The new system performs stable.According to the result of infra-red spectrophotometric analysis, chemical actions took place asP507and N235mixed. However, the extractant has a stable chemical structure after the chemical reactions.The P507-N235system, which can extracts rare earth directly without saponification,shorten the process line. The new system, witch has a good effect in extraction and highseparation coefficient, also easy in stripping. In addition, the organic phase has a stable chemicalstructure and could be recycled. It was a feasible technology proved by experiment. Owing toextraction without saponification, the new process can significantly lowering ammonia nitrogenwastewater and and reduces the production cost. The new system is a green metallurgicaltechnology.
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