Study on Purification of U Scraps in Continuous Countercurrent Extractor

In this paper, the feasibility of continuous countercurrent extractor (CCE) applied in extraction of U scraps rather than mixer-settler was studied. Effects of rotation Reynolds number, residence time on extraction and reverse extraction efficiency were investigated respectively. During the process, impurity content in raw material had a slight effect on extraction. Under the optimum conditions of O/A phase ratio of 1.2 and rotation Reynolds number of 13824, extraction degree of scrap pellet solution and alkalescence dreg lixivium were good with the residence time of 19 min and 26 min respectively. Under the best reverse extraction conditions of A/O phase ratio of 1.2, rotation Reynolds number of 23128 and residence time of 19 min, two kinds of raw material liquid mentioned as above could get better reverse extraction efficiency, while uranium concentration of raffinate phase and impurity content of reverse extract phase satisfied the technological requirement. This study verified the feasibility of CCE developed for purification of U scraps, identified the operation parameter, and provided an experimental basis for industrial expansion in the future.

Random errors in equilibrium composition of ternary liquid-liquid systems and their effect on the calculated number of theoretical stages of countercurrent extraction

The influence of size of random errors in the determination of ternary liquid-liquid equilibrium concentrations on the accuracy of the calculated number of theoretical stages of a countercurrent extractor is evaluated by using five hypothetical systems differing in the extent of mutual solubility of components, tie-line slope, and type of binodal curve.