Mineral formation during simulated leaks of Hanford waste tanks

Deng, Youjun; Harsh, James B.; Flury, Markus; Young, James S.; Boyle, Jeffrey S.

doi:10.1016/j.apgeochem.2006.05.002

Cited by 50 publications

(64 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Studies conducted at Washington State University demonstrated that the presence of chemical elements such as cesium, potassium, strontium, calcium, and magnesium did not affect the formation of cancrinite and sodalite in the Hanford sediments under highly alkaline conditions (Deng et al 2006b). A 2.8 general mineral transformation pathway was observed in these studies: poorly crystalline aluminosilicate fi Linde Type A zeolite fi cancrinite/sodalite, with cancrinite and sodalite being the two stable phases (Deng et al 2006a). In earlier studies, the same group found that cancrinite, sodalite, LTA zeolite and allophane were identified as the new formation in these sediments (Mashal et al 2004;Mashal et al 2005b;Mon et al 2005).…”

Section: 7mentioning

confidence: 80%

Remediation of Uranium in the Hanford Vadose Zone Using Ammonia Gas: FY 2010 Laboratory-Scale Experiments

Szecsody¹,

Truex²,

Zhong³

et al. 2010

View full text Add to dashboard Cite

Executive SummaryThis investigation is focused on refining an in situ technology for vadose zone remediation of uranium by the addition of ammonia (NH 3 ) gas with no addition of water. The objectives were to: a) refine the technique of ammonia gas treatment, b) identify the geochemical changes in uranium surface phases, c) identify broader geochemical changes that occur, and d) predict and test injection of ammonia gas for intermediate-scale systems to identify process interactions that could impact field-scale implementation. For ammonia gas injection into vadose zone sediments to be successful as a uranium remediation technology, it needs to show decreased U mobility of the most mobile U phases (aqueous, adsorbed) in a variety of field conditions. Uranium is present in Hanford sediment include in multiple phases including aqueous U(VI)-carbonate complexes, adsorbed, uranium coprecipitated with carbonates, and U-bearing minerals Na-boltwoodite and uranophane. Ammonia treatment of sediments raises the pH in Hanford sediments from 8.0 to 11-13, which has resulted in a decrease in uranium mobility, as evidenced by decrease in aqueous and adsorbed uranium in 85% of the different sediments tested (different U surface phase distributions or NH 3 treatments) and an increase in 8M HNO 3 extracted U (hard to extract U phases, silicates/phosphates/oxides) for 79% of sediments tested. There were also inconsistent changes in two acetate extractions, likely the result of dissolution of multiple surface U phases (U-carbonates, Na-boltwoodite, uranophane). Surface phase analysis by laser induced fluorescence spectroscopy and extended x-ray absorption structure has showed essentially no U surface mineral change in sediments initially containing Na-boltwoodite, but some U surface phase changes in U-calcite coprecipitates to uranyl oxyhydroxide, Na-boltwoodite, and uranyl tricarbonate. Therefore, the ammonia gas treatment appears most effective for U present in the most mobile phases: aqueous U, adsorbed U, and carbonate associated U. NH 3 -treated sediments containing Na-boltwoodite and uranophane showed decreased leaching even though solid phase analysis showed little changes in the U mineralogy. The decreased leaching may be the result of other mineral precipitates coating these phases. Minerals that leached the most significant mass of ions were montmorillonite, muscovite, and kaolinite. A greater understanding of these dissolution/precipitation/coating processes is needed to predict the long-term impact on uranium mobility.Ammonia gas injection experiments conducted in 20-to 30-ft long 1-D systems and a layered 2-D radial flow system were used to characterize the physicochemical changes at the NH 3 reaction front and treatment coverage in heterogeneous sediments. For 5% NH 3 (95%N 2 ) injection, an average of 234 pore volumes were needed to achieve the elevated pH (10.2 to 11.4) of the reaction front observed, with 465 pore volumes needed to achieve pH equilibrium (pH = 11.88), at 4% water content and 35% porosity. The des...

show abstract

Section: 7mentioning

confidence: 80%

Remediation of Uranium in the Hanford Vadose Zone Using Ammonia Gas: FY 2010 Laboratory-Scale Experiments

Szecsody¹,

Truex²,

Zhong³

et al. 2010

View full text Add to dashboard Cite

show abstract

“…Therefore, red mud addition to soils produces an unintended alkaline extraction liberating organic matter to solution. Along with clay mineral dissolution (Fernandez et al 2009;Deng et al 2006) and sorption reactions (Konan et al 2012), the reaction of alkalinity with natural organic matter will therefore be one of the main short term mechanisms for pH buffering in red mud / soil mixtures. Also, at higher red mud loadings, where alkalinity may be present in excess, the supply of extractable organic matter may limit DOC concentrations.…”

Section: Resultsmentioning

confidence: 99%

Gypsum addition to soils contaminated by red mud: implications for aluminium, arsenic, molybdenum and vanadium solubility

Lehoux

Lockwood

Mayes

et al. 2013

Environ Geochem Health

View full text Add to dashboard Cite

Red mud is highly alkaline (pH 13), saline and can contain elevated concentrations of several potentially toxic elements (e. proportional to red mud addition, of up to 4 pH units (e.g. pH 7  11). Increasing red mud addition also led to significant increases in salinity, dissolved organic carbon (DOC) and aqueous trace element concentrations. However, the response was highly soil specific and one of the soils tested buffered pH to around pH 8.5 even with the highest red mud loading tested (33% w/w); experiments using this soil also had much lower aqueous Al, As, and V concentrations. Gypsum addition to soil / red mud mixtures, even at relatively low concentrations (1% w/w) was sufficient to buffer experimental pH to 7.5-8.5. This effect was attributed to the reaction of Ca 2+ supplied by the gypsum with OH -and carbonate from the red mud to precipitate calcite. The lowered pH enhanced trace element sorption and largely inhibited the release of Al, As and V. Mo concentrations, however, were largely unaffected by gypsum induced pH buffering due to the greater solubility of Mo (as molybdate) at circumneutral pH. Gypsum addition also leads to significantly higher porewater salinities and column experiments demonstrated that this increase in total dissolved solids persisted even after 25 pore volume replacements. Gypsum addition could therefore provide a cheaper alternative to recovery (dig and dump) for treatment of red mud affected soils. The observed inhibition of trace metal release within red mud affected soils was relatively insensitive to either the percentage of red mud or gypsum present, making the treatment easy to apply. However, there is risk that over-application of gypsum could lead to detrimental long term increases in soil salinity.g

show abstract

“…This geochemical process has been documented in experiments involving homogeneous nucleation, specimen clays, and pristine Hanford sediments (2,5,8,(10)(11)(12)16). This reduced contaminant mobility is significant given the severity of radioactive contamination at the Hanford site (15,18).…”

Section: Introductionmentioning

confidence: 99%

“…Considerable efforts have been made toward understanding the behavior of contaminants introduced into sediments surrounding high-level radioactive waste (HLRW) storage sites at several Department of Energy (DOE) facilities (Hanford Site, WA; Savannah River Site, SC; Oak Ridge Site, TN) (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Principal radionuclide contaminants at the Hanford Site- 137 Cs, 90 Sr, and 129 I-have markedly different reactive transport behaviors influenced by the chemical composition of the waste solution and its interaction with the solid phase (6,9,13,14).…”

Section: Introductionmentioning

confidence: 99%

Contaminant Desorption during Long-Term Leaching of Hydroxide-Weathered Hanford Sediments

Thompson

Steefel

Perdrial

et al. 2010

Environ. Sci. Technol.

View full text Add to dashboard Cite

BRIEF:Leaching waste-altered Hanford sediments with neutral solutions desorbs Sr from de novo waste-generated minerals and desorbs Cs from high-affinity ion exchange sites. 2 ABSTRACTMineral sorption/co-precipitation is thought to be a principal sequestration mechanism for radioactive 90 Sr and 137 Cs in sediments impacted by hyperalkaline, high-level radioactive waste (HLRW) at the DOE's Hanford Site. However, the long-term persistence of neoformed, contaminant bearing phases after removal of the HLRW source is unknown. We subjected pristine Hanford sediments to hyperalkaline Na-Al-NO 3 -OH solutions containing Sr, Cs, and I at 10 -5 , 10 -5 , and 10 -7 molal, respectively, for 182 days with either <10 ppmv or 385 ppmv pCO 2 . This resulted in the formation of feldspathoid minerals.We leached these weathered sediments with dilute, neutral-pH solutions. After 500 pore volumes (PV), effluent Sr, Cs, NO 3 , Al, Si and pH reached a steady-state with concentrations elevated above those of feedwater. Reactive transport modeling suggests that even after 500 PV, Cs desorption can be explained by ion exchange reactions, whereas Sr desorption is best described by dissolution of Sr-substituted, neo-formed minerals. While, pCO 2 had no effect on Sr or Cs sorption, sediments weathered at <10ppmv pCO 2 did desorb more Sr (66% vs. 28%) and Cs (13% vs. 8%) during leaching than those weathered at 385 ppmv pCO 2 . Thus, the dissolution of neo-formed aluminosilicates may represent a long-term, low-level supply of 90 Sr at the Hanford site.

show abstract

Mineral formation during simulated leaks of Hanford waste tanks

Cited by 50 publications

References 33 publications

Remediation of Uranium in the Hanford Vadose Zone Using Ammonia Gas: FY 2010 Laboratory-Scale Experiments

Remediation of Uranium in the Hanford Vadose Zone Using Ammonia Gas: FY 2010 Laboratory-Scale Experiments

Gypsum addition to soils contaminated by red mud: implications for aluminium, arsenic, molybdenum and vanadium solubility

Contaminant Desorption during Long-Term Leaching of Hydroxide-Weathered Hanford Sediments

Contact Info

Product

Resources

About