Development of a reactive zone technology for simultaneous in situ immobilisation of radium and uranium

Burghardt, Diana; Kassahun, Andrea

doi:10.1007/s00254-005-0093-0

Cited by 41 publications

(33 citation statements)

References 12 publications

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“…The addition of MnO 2 increased the efficiency of the uptake process under slightly reducing conditions by promoting the oxidation of Fe 2+ to Fe(III) oxides only on the surface of MnO 2 rather than in the bulk pore spaces as would occur under oxidizing conditions. The MnO 2 also occluded 226 Ra and, to a lesser extent, U (Burghardt and Kassahun, 2005). However, like zero-valent iron PRBs, a loss of permeability may result from the formation of voluminous Fe(III) oxide phases under aerobic conditions.…”

Section: Groundwater Remediation Strategies Based On U Reductionmentioning

confidence: 97%

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Campbell¹,

Gallegos²,

Landa

2015

Applied Geochemistry

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aspects of uranium mineralization, mining, milling, and remediation" (2014 U is overwhelmingly the most abundant at greater than 99% of the total mass of U. Prior to the 1940s, U was predominantly used as a coloring agent, and U-bearing ores were mined mainly for their radium (Ra) and/or vanadium (V) content; the bulk of the U was discarded with the tailings (Finch et al., 1972). Once nuclear fission was discovered, the economic importance of U increased greatly. The mining and milling of U-bearing ores is the first step in the nuclear fuel cycle, and the contact of residual waste with natural water is a potential source of contamination of U and associated elements to the environment. Uranium is mined by three basic methods: surface (open pit), underground, and solution mining (in situ leaching or in situ recovery), depending on the deposit grade, size, location, geology and economic considerations (Abdelouas, 2006). Solid wastes at U mill tailings (UMT) sites can include both standard tailings (i.e., leached ore rock residues) and solids generated on site by waste treatment processes. The latter can include sludge or ''mud'' from neutralization of acidic mine/mill effluents, containing Fe and a range of coprecipitated constituents, or barium sulfate precipitates that selectively remove Ra (e.g., Carvalho et al., 2007). In this chapter, we review the hydrometallurgical processes by which U is extracted from ore, the biogeochemical processes that can affect the fate and transport of U and associated elements in the environment, and possible remediation strategies for site closure and aquifer restoration. This paper represents the fourth in a series of review papers from the U.S. Geological Survey (USGS) on geochemical aspects of UMT management that span more than three decades. The first paper (Landa, 1980) in this series is a primer on the nature of tailings and radionuclide mobilization from them. The second paper (Landa, 1999) includes coverage of research carried out under the U.S. Department of Energy's Uranium Mill Tailings Remedial Action Program (UMTRA). The third paper (Landa, 2004) reflects the increased focus of researchers on biotic effects in UMT environs. This paper expands the focus to U mining, milling, and remedial actions, and includes extensive coverage of the increasingly important alkaline in situ recovery and groundwater restoration.Ó 2014 Published by Elsevier Ltd.

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Section: Groundwater Remediation Strategies Based On U Reductionmentioning

confidence: 97%

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Campbell¹,

Gallegos²,

Landa

2015

Applied Geochemistry

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“…Note that, if the experiments are performed under (too high) mixing conditions or in columns, increased contaminant removal efficiency in the presence of MnO 2 could have been reported. For example, Burghardt and Kassahun [58] reported increased uranium and radium removal in "Fe 0 + MnO 2 " systems comparatively to the system with Fe 0 alone. The results of Burghardt and Kassahun [58] are by no means contradictory to those reported here and elsewhere [40] because the net effect of MnO 2 is to promote iron hydroxide formation (or to sustain corrosion) resulting in an increased contaminant removal capacity.…”

Section: Mb Discoloration By Different Agents and Discoloration Mechamentioning

confidence: 99%

Characterizing the discoloration of methylene blue in Fe0/H2O systems

Noubactep¹

2009

Journal of Hazardous Materials

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Methylene blue (MB) was used as a model molecule to characterize the aqueous reactivity of metallic iron in Fe(0)/H(2)O systems. Likely discoloration mechanisms under used experimental conditions are: (i) adsorption onto Fe(0) and Fe(0) corrosion products (CP), (ii) co-precipitation with in situ generated iron CP, (iii) reduction to colorless leukomethylene blue (LMB). MB mineralization (oxidation to CO(2)) is not expected. The kinetics of MB discoloration by Fe(0), Fe(2)O(3), Fe(3)O(4), MnO(2), and granular activated carbon were investigated in assay tubes under mechanically non-disturbed conditions. The evolution of MB discoloration was monitored spectrophotometrically. The effect of availability of CP, Fe(0) source, shaking rate, initial pH value, and chemical properties of the solution were studied. The results present evidence supporting co-precipitation of MB with in situ generated iron CP as main discoloration mechanism. Under high shaking intensities (>150 min(-1)), increased CP generation yields a brownish solution which disturbed MB determination, showing that a too high shear stress induced the suspension of in situ generated corrosion products. The present study clearly demonstrates that comparing results from various sources is difficult even when the results are achieved under seemingly similar conditions. The appeal for an unified experimental procedure for the investigation of processes in Fe(0)/H(2)O systems is reiterated.

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“…To date, characterizing processes yielding contaminant removal in Fe 0 /sand/H 2 O systems using the MB discoloration approach [15,17,18,23,33] has successfully confirmed/explained findings from column experiments that sand admixture improves the long-term decontamination efficiency [13,34,35]. A similar success for batch experiments is still to be demonstrated as the results presented in ref [29] have not unequivocally established the impact of MnO 2 addition on the behaviour of the Fe 0 /sand system towards MB discoloration.…”

Section: Introductionmentioning

confidence: 99%

Characterizing the impact of sand addition on the efficiency of granular iron for contaminant removal in batch systems

Miyajima¹,

Noubactep²

2015

Chemical Engineering Journal

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Development of a reactive zone technology for simultaneous in situ immobilisation of radium and uranium

Cited by 41 publications

References 12 publications

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Characterizing the discoloration of methylene blue in Fe0/H2O systems

Characterizing the impact of sand addition on the efficiency of granular iron for contaminant removal in batch systems

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