Patent ID: 8557120

Claim:
A process for separating plutonium, neptunium, americium and curium in a grouped manner from a first acidic aqueous phase, the first acidic aqueous phase comprising 2 to 5 moles/L of nitric acid, the plutonium, the neptunium, the americium, the curium and fission products including lanthanides and yttrium, the process comprising: (a) co-extracting at least the plutonium, the neptunium, the americium, the curium, the lanthanides, and the yttrium from the first acidic aqueous phase, by: bringing the first acidic aqueous phase into contact with an immiscible organic phase, the organic phase comprising a first extractant and a second extractant, the first extractant being an extractant capable of extracting the plutonium, the neptunium, the americium, the curium, the lanthanides, and the yttrium from the first acidic aqueous phase, and the second extractant being a dialkylphosphorous-based acid capable of extracting the plutonium, the neptunium, the americium, the curium, the lanthanides, and the yttrium from a second acidic aqueous phase having a pH of 3; and separating the first acidic aqueous acidic phase from the organic phase; and (b) stripping the plutonium, the neptunium, the americium, the curium from the organic phase resulting from (a) without stripping the lanthanides and the yttrium, by: bringing the organic phase into contact with the second acidic aqueous phase having a pH of 3, the second acidic aqueous phase comprising an aminopolyacetic acid for complexing the plutonium, the neptunium, the americium, the curium, a hydroxycarboxylic acid, a base and at least one reducing agent selected from the group consisting of a hydrazine, a hydroxylamine, an oxime and a hydroxyurea; and separating the organic phase from the second acidic aqueous phase, thereby separating the plutonium, the neptunium, the americium, the curium from the lanthanides and the yttrium; wherein the first extractant is N,N′-dimethyl-N,N′-dioctylhexylethoxymalonamide (DMDOHEMA), and the second extractant is 2-ethylhexyl-2-ethylhexylphosphonic acid (HDEHP).