Uranium retention on iron oxyhydroxides in post-mining environmental conditions

Area of Science:

• Environmental Science
• Geochemistry
• Mineralogy

Background:

• Uranium mining poses environmental risks due to potential uranium migration.
• Understanding uranium immobilization mechanisms in waste rocks is critical for environmental management.

Purpose of the Study:

• To investigate uranium migration and immobilization mechanisms in iron oxyhydroxides within granitic waste rock environments.
• To identify the role of ferrihydrite, lepidocrocite, and goethite in controlling uranium mobility.

Main Methods:

• Analysis of environmental samples from technosols, mine drainage, and mine waters.
• Utilized Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy.
• Employed mineralogical and geochemical techniques including SEM, WDS, ICP-MS/OES, and XRD.

Main Results:

• Iron oxyhydroxides play a significant role in uranium immobilization and re-concentration.
• Uranyl ternary surface complexes with phosphate or organic matter were identified on ferrihydrite.
• Goethite and lepidocrocite act as secondary uranium sinks.

Conclusions:

• Iron oxyhydroxides effectively control uranyl mobility in supergene conditions.
• The study highlights the importance of mineralogical composition in uranium environmental fate.