Third phase
Third phase is the term for a stable emulsion which forms in a solvent extraction system when the original two phases (aqueous and organic) are mixed.
One term for the thrid phase found in PUREX plants is crud (Chalk River Unknown Deposit). One common crud is formed by the reaction of zirconium salts (from fission) with degraded tributyl phosphate (TBP). The TBP degrades into dibutyl hydrogen phosphate and then into butyl dihydrogen phosphate. The dibutyl hydrogen phosphate and the zirconium can form polymeric solid which is very insoluble.