Laboratory column experiments and transport modeling to evaluate retardation of uranium in an aquifer downgradient of a uranium in-situ recovery site

Dangelmayr, Martin; Reimus, Paul W.; Wasserman, Naomi L.; Punsal, Jesse J.; Johnson, Raymond H.; Clay, J. T.; Stone, Jeff

doi:10.1016/j.apgeochem.2017.02.018

Cited by 43 publications

(13 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because of the perfect inverse correlation of log β and S sorp , the latter parameter was fixed in all simulations to be 60.2 mmol/kg-sediment, a value estimated from the product of sediment-specific surface area measurements and literature values of uranium sorption densities per unit area. Prior estimates of SRH sediment specific surface area ranged from 3.9 to 13.1 m 2 /g, and uranium sorption site densities for quartz have been reported at 4.81 and 5.1 sites/nm 2 , , producing S sorp estimates that range from 23.7 mmol/kg-sediment to 96.7 mmol/kg-sediment, with a mean value of 60.2 mmol/kg-sediment. We recognize that many sorption sites on aquifer sediments (and almost all of those at which reduction likely occurred) would likely not be associated with quartz.…”

Section: Resultsmentioning

confidence: 99%

“…Uranium sorption was simulated by incorporating a nonelectrostatic, generalized composite surface complexation model (GC SCM) with up to three types of sorption sites in the transport calculations . Briefly, the GC SCM is a semiempirical approach in which it is assumed that the surface composition of the mineral assemblage is inherently too complex to be quantified in terms of the contributions of individual phases to adsorption. , Instead, it is assumed that the adsorptive reactivity of the surface can be described by surface complexation equilibria written with “generic” surface functional groups, with sorption coefficients and site densities for each reaction determined by matching experimental data.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Thus, the model allowed up to three sorption reactions, with equilibrium constants β i and initial molar site densities per unit mass of sediment, S sorp,i , being treated as adjustable parameters. The augmented PHREEQC thermodynamic database used by Dangelmayr et al 10,13 was implemented in the model. Uranium reduction was modeled as a second-order irreversible reaction between adsorbed U(VI) and a generic electron transfer reactant on the sediment surfaces assumed to be located at the adsorption site (several studies have shown that U(VI) reduction is facilitated at mineral surfaces after sorption 14−16 ):…”

Section: Environmental Science and Technologymentioning

confidence: 99%

See 3 more Smart Citations

Uranium Natural Attenuation Downgradient of an in Situ Recovery Mine Inferred from a Cross-Hole Field Test

Reimus

Dangelmayr

Clay³

et al. 2019

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

A field test was conducted at a uranium in situ recovery (solution mining) site to evaluate postmining uranium natural attenuation downgradient of an ore zone. Approximately 1 million liters of water from a previously mined ore zone was injected into an unmined ore zone that served as a proxy for a downgradient aquifer, while a well located approximately 23 m away was pumped. After 1 year of pumping, only about 39% of the injected U(VI) was recovered, whereas essentially 100% of coinjected chloride was recovered. A geochemical/transport model was used to simultaneously match the chloride and uranium concentrations at the pumping well while also qualitatively matching aqueous 238U/235U ratios, which reflect uranium removal from solution by reduction. It was concluded that ∼50% of the injected U(VI) was reduced to U(IV), although the reduction capacity in the flow pathways between the injection and production wells was estimated to be nearly exhausted by the end of the test. Estimating the reduction capacity of the downgradient aquifer can inform restoration strategy and offer a useful metric for regulatory decisions concerning the adequacy of restoration. U(VI) reduction should be effectively irreversible in these anoxic environments, which differ greatly from shallow oxic environments where U(IV) is readily reoxidized.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Environmental Science and Technologymentioning

confidence: 99%

See 2 more Smart Citations

Uranium Natural Attenuation Downgradient of an in Situ Recovery Mine Inferred from a Cross-Hole Field Test

Reimus

Dangelmayr

Clay³

et al. 2019

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Simon et al [31] conducted a batch test and column leaching experiment and then calibrated the reaction-transport parameters for in situ mining using the geochemical code CHESS and the hydrodynamic geological code HYTEC. Dangelmayr et al [32] studied the decay process of uranium under a certain hydraulic gradient via column leaching experimentation and the PHREEQC model. Gomez et al [33] simulated uranium migration in underground water and obtained the reduction conditions of secondary uranium.…”

Section: Introductionmentioning

confidence: 99%

Coupled Multifield Response to Coordinate Mining of Coal and Uranium: A Case Study

Zhang

Yuan

Wei

et al. 2020

Water

View full text Add to dashboard Cite

The coordinate mining of stack resources in the Ordos Basin, which involves the coupling effects of stress fracture, seepage, and reactive solute transport, plays an important role in resource exploration and environment protection. A coupled multiphysical–chemical model, involving a modified non-Darcy flow model, a leaching solution reaction, and a reactive solute transport model, was developed in this study. The Fast Lagrangian Analysis of Continua -Computational Fluid Dynamics (FLAC3D-CFD) simulator coupled with the developed models was used to investigate the evolution and morphology of mining-induced multifield coupling for the scenarios of concurrent mining and asynchronous mining of coal and uranium. As mining advanced to 160 m, the maximum principle stress characterized by a stress shell was observed. As mining progressed to 280 m, a rupture occurred, and a new stress shell was generated as a rear skewback was formed by the concentrated stress of the stope. An “arch-shaped” fracture field combined with a “saddle-shaped” seepage field was identified in the destressed zone of the stress shell. In the coordinated mining of uranium prior to coal, “funnel-shaped” and “asymmetric saddle-shaped” morphologies of the leaching solution were found during coal mining for ventilation in the stope and mining face. By contrast, “saddle-shaped”, “inclined funnel-shaped”, and “horizontal” morphologies of the leaching solution were observed for a short period for ventilation of the stope and mining face for coal mining prior to uranium mining, uranium mining prior to coal mining, and synchronized coal and uranium mining. A dynamic stress response was obtained in the coal seam, followed by the conglomerate aquifer and the uranium deposits. The diffusion depth of the solution was negatively correlated with the injection velocity and the pumping ratio and positively correlated with the diffusion coefficient. A dynamic increase in diffusion depth was observed as the diffusion coefficient increased to 1 × 10−4 m2/s.

show abstract

Mine Waste Effects on Water and Soil in Native American Land in WesternUSA

Cerrato

DeVore

Velasco

2019

Encyclopedia of Water

View full text Add to dashboard Cite

The legacy of mining activities on Native American land has resulted in an extensive number of sites with elevated metal concentrations in water and soil; many of these sites have received limited or no remedial action. The reclamation and cleanup of these sites represents a major burden for communities, and authorities at the tribal, state, and federal levels. The limited knowledge of the characteristics of these sites limits the ability to adequately assess the risk to metal exposures among communities living near these sites and develop feasible remediation alternatives. This article attempts to critically synthesize the state of the problem and provide an overview of the existing knowledge related to the occurrence, transport, and remediation of metals in these abandoned mine waste sites. The physical and biogeochemical aspects reviewed in this article have relevant implications for Native American communities, decision‐makers, stakeholders, and environmental scientists.

show abstract

Laboratory column experiments and transport modeling to evaluate retardation of uranium in an aquifer downgradient of a uranium in-situ recovery site

Cited by 43 publications

References 49 publications

Uranium Natural Attenuation Downgradient of an in Situ Recovery Mine Inferred from a Cross-Hole Field Test

Uranium Natural Attenuation Downgradient of an in Situ Recovery Mine Inferred from a Cross-Hole Field Test

Coupled Multifield Response to Coordinate Mining of Coal and Uranium: A Case Study

Mine Waste Effects on Water and Soil in Native American Land in WesternUSA

Contact Info

Product

Resources

About