Speciation and Mobility of Uranium in Waste Materials Generated by Mining and Hydrometallurgy in Jaduguda, India

Abstract

Samples of fine tailings from shallow depths of a waste depository (i.e., tailings pond) from uranium (U) ore processing in Jaduguda, India, were investigated to determine the speciation of the U and its association with certain physicochemical parameters. The aim was to understand the phenomena that can lead to the migration of U from the tailings pile to the adjoining environment. Natural processes were found to impact the physicochemical features of the tailings, as reflected in samples collected from a non-operational (first stage) and an operational (third stage) tailings pond. The average concentrations of U were 63.73 ± 5.34 mg/kg and 91.98 ± 9.33 mg/kg in the first- and third-stage ponds, respectively. A sequential extraction of tailings samples showed that the major fraction of U was bound to the residual phase, followed by an iron/manganese (Fe/Mn) oxide phase. The average fractions of U bound to these two phases were 38.7% and 35.8% as residual and 30.7% and 25.1% as Fe/Mn oxide in the first- and third-stage ponds, respectively. The findings demonstrate that, on average, 5% and 2.5% of the total U in the samples from the nonoperational and operational tailings ponds were active/mobile. This low mobility substantially minimizes the impact on the adjoining environment. In addition, the state-of-the-art technology used for waste immobilization, along with the site condition, are favorable for the long-term storage of the fine tailings from the ore-processing unit.