稀土皂化P_(507)-煤油有机相的制备及相关反应

Preparation of Rare Earth Saponified P_(507)-kerosene Organic Phase and the Relating Reactions

本研究的目的是提供一种以碳酸稀土为皂化剂的稀土皂化P507-煤油有机相的制备方法。为此,系统考察了多种因素,例如,碳酸稀土用量、杂质离子硫酸根浓度、游离稀土离子浓度、相比和接触时间等因素,对稀土萃取率、分相性能和稀土负载浓度的影响。结果表明:当P507-煤油有机相与含游离稀土浓度在1 mmol/L以上的水相接触混合时,P507-煤油有机相的皂化可以快速地与加入的固体碳酸稀土反应,形成稀土皂化有机相。其皂化反应可以在几分钟之内完成,比水相中不含游离稀土离子时要快很多,这是因为受动力学条件限制的直接皂化反应已经变成了两个分立的反应:P507-煤油有机相与游离稀土离子的皂化反应以及该皂化反应析出的质子与碳酸稀土的溶解反应。基于这一特征,把P507-煤油有机相的稀土皂化设计成了多级逆流萃取皂化过程,该过程可以连续产出合格有机相并使水相在体系中保持循环。分液漏斗模拟结果证明了多级逆流皂化的可行性,确定了最佳的萃取相比为1∶1,皂化有机相的稀土负载浓度在0.12 mol/L以上。

In order to lower the consumption of base in the extraction separation of rare earths, RE saponification of P507 - kerosene organic phase （ P - kop） is being employed to replace sodium or ammonium saponification. The aim of this paper is to propose a method for the preparation of RE saponified P - kop with rare earth carbonate as saponification agents. Therefore, factors that influence on the rare earth loaded concentration in P- kop and the phase separation performance were examined, such as the dosage of rare earth carbonate, the content of impurity ions （ SO4^2- ） , the free rare earth ion concentration in aqueous phase and the phases ratio. It was found that when the P - kop is mixed with aqueous phase containing free rare earth con- centration over 1 mmol/1 and solid rare earth carbonate, the saponification of P - kop can finish in a few minutes, which is much sooner than that when no free rare earth ions existing in aqueous phase because the kinetic limited direct saponification reaction has been changed by two separating reactions ： the extraction reaction between P - kop and free rare earth ions and the dissolve reaction of rare earth carbonate with proton liberated from extraction reaction. With this characterization, the RE sa- ponification of P - kop has been designed to a multi - stages counter - saponification process which continuously outputs RE saponified P - kop and remains the aqueous phase recycling. The results of simulation experiment in funnel prove that the mul- tistage countereurrent saponification is feasible, and the optinmm phase ratio is determined to be 1 ： 1, the loaded rare earth concentrations in saponified P - kop reach 0. 12tool / L or more.