Thomson and two co-authors, reported in 1986 that a three-phase investigation has been conducted on groundwater quality impacts of the underground disposal of tailings from acid-leach milling of uranium ores. These phases included field collection and analysis of samples obtained during backfilling of mill tailings in empty underground mine stopes, collection of soil samples from mill tailings piles and previously backfilled stopes, and evaluation of thermodynamic constraints on possible geochemical transformations. Contaminants of principal concern include As, Mo, Se, U, V and Ra-226.
The investigation has shown that short-term degradation of groundwater due to backfill disposal of the sand fraction of uranium tailings is negligible. Long-term effects, defined as those occurring after mining operations cease and the mine fills with water, are predicted to also be very small. This is attributed to immobilization of pollutants through chemical reduction and precipitation, as well as adsorption onto aquifer materials. This conclusion is substantiated, in part, by observation of high concentrations of most of the contaminants on the silt and clay fraction of the soil samples collected, in contrast to the concentrations found on the sand fraction.
They concluded that the strong propensity of actinides to form complexes with various natural organic macromolecules (humic substances) facilitates the fast distribution of radioactive pollutants in an aquatic environment (Grenthe et al., 1992). On the other hand, the adsorption of actinides on ubiquitous clay minerals represents an important retardation mechanism (Thompson et al., 1986). Although adsorption of actinides at the water–mineral interface nowadays is extensively studied by experiment, (Dent et al., 1992; Reich et al., 1996, 1998, 2007; Thompson et al., 1998; Sylwester et al., 2000; Hennig et al., 2002; Den Auwer et al., 2003; Chisholm-Brause et al., 2004; Baumann et al., 2005; Wang et al., 2005; Křepelová et al., 2006, 2007, 2008) only scarce knowledge is available at the atomic scale.
Original working URL: https://www.sciencedirect.com/science/article/abs/pii/0883292786900193
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