Abstract
In the present work rare-earth recovery was performed from a residue of a hydrometallurgical process based on sulphuric acid leaching of lamp phosphor waste by which the red phosphor Y2O3:Eu3+ was removed for further recovery. The undissolved residue is rich in lanthanum, cerium and the valuable terbium, present as phosphates and aluminates in the green and blue phosphors. The process here proposed is based on an integrated pyro-hydrometallurgical approach involving a thermal treatment (roasting in the presence of sodium carbonate) aimed at converting rare-earth phosphates into oxides, which can be more easily leached by mineral acids (HCl and H2SO4) in a further leaching step. Rare-earth recovery from the leachate was then performed by solvent extraction with the extractant di-(2-ethylhexyl)phosphoric acid, D2EHPA, followed by precipitation with oxalic acid and calcination. 82% Ce, 75% La and 82% Tb were recovered as mixed La2O3 + CeO2 oxide (99% purity) and Tb4O7 (64% purity).
| Original language | English |
|---|---|
| Pages (from-to) | 38-44 |
| Number of pages | 7 |
| Journal | Hydrometallurgy |
| Volume | 187 |
| DOIs | |
| Publication status | Published - Aug 2019 |
Keywords
- Rare-earth recovery
- Lamp phosphor waste
- Sodium carbonate roasting
- Solvent extraction
Project and Funding Information
- Project ID
- info:eu-repo/grantAgreement/EC/H2020/680629/EU/New Recovery Processes to produce Rare Earth -Magnesium Alloys of High Performance and Low Cost/REMAGHIC
- Funding Info
- This work has received funding from the European Union's Horizon2020 research and innovation programme under Grant Agreement No.680629 (REMAGHIC: New Recovery Processes to produce Rare Earth-Magnesium Alloys of High Performance and Low Cost) (project website:http://www.remaghic-project.eu/). The authors acknowledge Relightsrl for providing the lamp phosphor powder.