Long-term leaching of uranium from different waste matrices

Area of Science:

• Environmental Science
• Geochemistry
• Mining Engineering

Background:

• Uranium and copper mining generate metallurgical wastes and ore samples containing uranium.
• Understanding uranium release from these materials is crucial for environmental risk assessment.

Purpose of the Study:

• To investigate uranium leaching behavior from mining wastes and ore samples.
• To identify the mechanisms governing uranium release under semi-dynamic conditions.

Main Methods:

• Semi-dynamic leaching tests over 142 days using distilled water and 0.1N NaNO(3).
• Laser fluorimetry for determining total uranium content in leachates.
• Calculation of cumulative leach fraction (CLF), diffusion coefficients, and bulk release.

Main Results:

• Uranium release (CLF) varied by matrix, ranging from 0.07% to 0.39% with distilled water and 0.05% to 0.59% with 0.1N NaNO(3).
• Uranium release was slow, initially faster then reaching a near steady state.
• Surface wash-off and diffusion were identified as the primary release mechanisms.

Conclusions:

• Semi-dynamic leaching with weak solvents effectively determines leaching parameters for mobile uranium.
• The study identified key mechanisms controlling uranium release from diverse mining matrices.
• Findings aid in assessing environmental risks associated with uranium mining waste.