Study On The Dynamic Model Of Extraction And Stripping Of Uranium And Nitric Acid In The Second Cycle Of Uranium

The computer simulation research of the corresponding components and extraction equipment of the process of prex can carry out the analysis and optimization of the process in a wide range,find out the best process conditions,and improve the utilization rate of uranium.However,there are some problems in the previous simulation study,such as the coupling degree of extraction process and equipment is not high,the extraction process is too ideal,and the transient process simulation is less.In this paper,extraction kinetics is used to describe the extraction process with chemical reaction,and the coupling degree of extraction process and equipment is enhanced by the relationship between specific phase area and apparent rate constant and equipment size and selection.The computer dynamic simulation of extraction and stripping process in the second cycle purification of uranium in the process of prex is carried out.First of all,the mathematical model of extraction kinetics was established through literature research and kinetic experiments.The experimental results show that the extraction process is controlled by diffusion,the speed control step is water phase diffusion,the reverse extraction process is controlled by chemical reaction,and the speed control step is the decomposition reaction of the extraction compound molecules at the interface.Secondly,the relationship between the size of the mixing clarifier,the impeller type,the rotating speed,the temperature and the kinetic model of extraction and stripping was established by using the specific phase area and the apparent rate constant.The purpose of coupling the extraction process and the equipment was realized,and the single-stage model and the cascade model of extraction and stripping process were established.Finally,the simulation results of single-stage and cascade transient models are verified.The single-stage extraction transient model is in good agreement with the experiment in the system of low concentration of uranium and low speed,while in the system of high speed and high concentration,the extraction rate of model uranium is higher than the actual extraction rate,and the extraction rate of model nitric acid is lower than the actual extraction rate.Under the condition of high speed and high concentration,the extraction rate of model uranium is higher than the actual extraction rate.This is caused by the different selection of experimental balance parameters and equipment parameters.The concentration distribution of uranium and nitric acid in organic phase,aqueous phase and water phase with time was obtained by the model of series transient extraction and stripping,and the above concentration in equilibrium was consistent with the results in literature.It is proved that the transient model of extraction and stripping is feasible.