Dileesha Jayahansani Kotte-Hewa (Uva Wellassa University, SCK CEN, KU Leuven), Delphine Durce, Sonia Salah (SCK CEN), and Erik Smolders (KU Leuven) have published a new study on how ageing processes improve rare earth element (REE) retention in passive treatment systems for acid mine drainage.
The study shows that ageing these systems for one year at neutral pH (∼6) significantly enhances REE removal compared to early-stage results. This improvement is linked to the slow dissolution of excess limestone, which raises the pH and boosts REE sorption, particularly onto amorphous Fe and Al mineral phases such as basaluminite and gibbsite. Interestingly, gypsum remains the only crystalline phase formed, while Fe- and Al-precipitates remain amorphous even after a year. At acidic pH (∼4), ageing altered the binding phases of medium REEs but had no effect on total REE retention.
Reference:
Kotte-Hewa, D.J., Durce, D., Salah, S., Smolders, E. (2025). Effects of ageing on rare earth elements retention and the structure of secondary mineral phases formed during acid mine water alkalinization. Journal of Hazardous Materials Advances, 19, 100810. https://doi.org/10.1016/j.hazadv.2025.100810
Acknowledgements:
This research was conducted by teams from Uva Wellassa University (Sri Lanka), the Belgian Nuclear Research Centre SCK CEN, and KU Leuven. The article is published open access under a Creative Commons license.
