Route A: Acid leaching + solvent extraction (the workhorse approach)
A common flowsheet is:
- Acid leach (often HCl) to put REEs into solution
- Impurity removal (pH control, selective precipitation)
- Solvent extraction to separate REEs into cuts
- Finishing to oxides/carbonates
Peer-reviewed work specifically covers yttrium and europium recovery from waste tube-light phosphor powder leach liquor using solvent extraction, and then chemical reduction steps that help with Eu separation.
Route B: Chlorination roasting + leaching (another proven pathway)
Some research demonstrates recovery of Y and Eu from waste phosphors through chlorination roasting followed by water leaching, then downstream purification.
The europium-specific trick: redox chemistry
Europium is one of the few rare earths where oxidation state manipulation can be used to separate it more cleanly from neighbors. Many practical flowsheets leverage a reduction step (Eu³⁺ toward Eu²⁺ behavior) to enable selective separation, because Eu sits in a tight region of the rare earth series.