Destruction of Emulsions Stabilized by Precipitates of Zirconium and Tributyl Phosphate Degradation Products

In solvent extraction for nuclear fuel reprocessing, a stable emulsion called “crud” is formed at the interface between the organic and aqueous phases. Crud is an emulsion stabilized by finely dispersed solids. Process disturbances are often induced by crud. Accordingly, crud should be eliminated from the interface in the extractors. The eliminated crud is stable and highly radioactive; thus, the treatment of this crud may be difficult. Complexes of zirconium and tributyl phosphate (TBP) degradation products, such as phosphoric acid (H₃PO₄) and mono-n-butyl phosphate (H₂MBP), are one source of the fine particles that stabilize emulsions in the extraction process. A chemical treatment method to demulsify crud stabilized by precipitates of Zr-H₃PO₄ and Zr-H₂MBP is studied. Experimental results indicate that neutralization by an alkaline solution, particularly sodium carbonate, is very effective for the destruction of this crud.