Recovery of uranium from low-grade tailings by electro-assisted leaching

Abstract

Approximately 24 billion tons of existing hazardous radioactive waste, such as uranium tailings can yield nearly 9.6 million tons of uranium, which can be made available for nuclear industrial production for almost the next 100 years as per the current consumption levels. However, the extraction of uranium from tailings is highly challenging owing to the high proportion of the gangue content and relatively low content of the soluble U(VI). In this study, we engineered an innovative electro-assisted leaching (EAL) method, based on the dilute acid leaching (AL) method integrated with an electric field, for uranium recovery from low-grade uranium tailings. The proposed method offers advantages in terms of efficiency and environmental pollution control. In our experiments, the EAL method displayed a higher uranium extraction capacity (95%) than the traditional methods (55%) under the same conditions, during a rapid leaching of uranium tailings (containing 0.008% uranium) collected from a radioactive tailings dam in China. The excellent performance of EAL stemmed from (i) the continuous supply of oxidants (ferric ions), which ensured a high uranium solubility (i.e., transformation of U(IV) to U(VI) and (ii) the effect of the electric field on ion migration, which allowed for efficient dissociation of uranium from the complicated multi-mineral composition. In addition, these results demonstrated that EAL could be an efficient and environment-friendly scalable method for extracting valuable metals from low-grade ores or tailings.