乏燃料后处理萃取过程中的界面污物

Crud in the Solvent Extraction Process for Spent Fuel Reprocessing

在乏燃料后处理萃取工艺工程中 ,萃取剂和溶剂的辐解以及料液中不溶性固体微粒的存在导致产生界面污物。界面污物严重影响萃取柱的正常操作。文章就有关界面污物的研究状况进行概要评述。目前 ,普遍认为 ,在Purex流程萃取过程中 ,尤其是在一循环中 ,界面污物的产生与Zr和TBP降解产物HDBP、H2 MBP、H3 PO4 形成的沉淀以及料液中存在的不溶性RuO2 、Pd等微粒的表面化学现象有关。沉淀是否产生以及形成的界面污物类型与HDBP/Zr摩尔比和水相条件密切相关。此外 ,煤油等稀释剂的降解产物也是形成界面污物的一个不可忽略的因素。从萃取设备中排出的界面污物可用Na2 CO3 或草酸进行处理。在界面污物模拟实验中 ,需同时考虑Zr与TBP降解产物HDBP、H2 MBP、H3 PO4 形成沉淀和不溶性微粒RuO2 。

The crud occurred in Purex process is caused by the degradations of extractant and solvent and the existence of insoluble solid particle in the nuclear fuel reprocessing. The crud seriously affects the operation of the extraction column. The present paper reviews the study status on the crud in the Purex process. It is generally accepted that in the Purex process, particularly in the first cycle, the crud occurrence is related to the capillary chemistry phenomena resulting from the deposits of Zr with TBP degradation products HDBP, H2MBP, H3PO4 and the insoluble particle RuO2 and Pd. The occurrence of deposits and the type of crud are tightly related to the molar ratio of HDBP and Zr, and the aqueous pH. In addition, the effect of degradation products from the diluent, such as kerosene, is an unnegligible factor to cause the crud. The crud can be discharged from the extraction equipment with Na2CO3 or oxalic acid. In the study on simulating the crud, the effects of the deposits of Zr with TBP degradation products HDBP, H2MBP and H3PO4, and the insoluble particle RuO2 and Pd should be considered at the same time.