Effects of the different conditions of uranyl and hydrogen peroxide solutions on the behavior of the uranium peroxide precipitation

Kim, Kwang‐Wook; Hyun, Jun-Taek; Lee, Keun‐Young; Lee, Eil‐Hee; Lee, Kune-Woo; Song, Kiwon; Moon, Jei‐Kwon

doi:10.1016/j.jhazmat.2011.07.032

Cited by 65 publications

(18 citation statements)

References 8 publications

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“…The size of the uranium particles precipitated from the spent filter aid also shows the same characteristics. It has been reported that the individual particle size decreases with increase in the pH and ionic strength, and individual particles tend to aggregate at higher pH and ionic strength [19]. Our results roughly correspond to these reported tendencies with respect to the particle size.…”

supporting

confidence: 91%

“…As a result, a sufficient amount of uranium was precipitated after 2 h (more than 99.5 wt%). It has been reported that the precipitation time increases with an increase in the ionic strength and pH of the solutions, and decreases at higher uranium concentrations [19]. In the present system, although the ionic strength and pH of the solutions are high (assumed ionic strength is above 2.5, pH = 3), the precipitation reaction is almost complete within a few hours.…”

Section: Effect Of Precipitation Time On Precipitation Ratiomentioning

confidence: 52%

“…precipitation ratio It has been reported that the precipitation time depends on the concentration of uranium and the ionic strength of solutions [19]. Sample solutions were prepared by dissolving the CaF 2 sludge (1 g) in HCl (1 M, 50 mL), followed by filtering of the residual solid phase and then H 2 O 2 was added to the filtrate in a molar ra-…”

Section: Effect Of Precipitation Time On Thementioning

confidence: 99%

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Technique for recovering uranium from sludge-like uranium-bearing wastes using hydrochloric acid

Ohashi

Nomura

Tsunashima

et al. 2013

Journal of Nuclear Science and Technology

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Sludge-like uranium-bearing wastes generated from uranium refining and conversion R&D facilities are stored at the Ningyo-toge Environmental Engineering Center of the Japan Atomic Energy Agency. So far, approximately 1500 t of uranium wastes with radioactivity levels exceeding 10,000 Bq/g have been generated. We have proposed an environmentally benign aqueous process for recovering uranium from wastes using hydrochloric acid (HCl). This makes it possible to dispose of the wastes easily, and to reclaim uranium as a resource. In this process, first, the uranium content in the calcium fluoride (CaF 2 ) sludge along with the entire sludge is dissolved almost completely in aqueous solutions containing HCl and aluminum chloride. The uranium species are then recovered as peroxide from the CaF 2 sludge solution. Their characteristics are similar to those specified for uranium ore concentrate. After recovering the uranium content, the uranium concentration in the solution is reduced to below 0.01 mg/L using an iminodiacetic chelating resin. Also, the uranium concentration of the precipitate generated by the neutralization of the barren solution falls below 1 Bq/g.

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supporting

confidence: 91%

Section: Effect Of Precipitation Time On Precipitation Ratiomentioning

confidence: 52%

Section: Effect Of Precipitation Time On Thementioning

confidence: 99%

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Technique for recovering uranium from sludge-like uranium-bearing wastes using hydrochloric acid

Ohashi

Nomura

Tsunashima

et al. 2013

Journal of Nuclear Science and Technology

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“…The formation of particles is a highly complex process, depending on numerous parameters. A formation of somewhat similar cylindrical particles has been demonstrated for UO 4 particles from a hydrogen peroxide solution, as well as UO 3 and U 3 O 8 under specific conditions [30][31]. The EDX analyses of the remaining particles in Fig.…”

Section: All Workhops -Aerosol Morphologysupporting

confidence: 67%

Uranium aerosols at a nuclear fuel fabrication plant: Characterization using scanning electron microscopy and energy dispersive X-ray spectroscopy

Hansson

Pettersson

Fortin³

et al. 2017

Spectrochimica Acta Part B: Atomic Spectroscopy

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Detailed aerosol knowledge is essential in numerous applications, including risk assessment in nuclear industry. Cascade impactor sampling of uranium aerosols in the breathing zone of nuclear operators was carried out at a nuclear fuel fabrication plant. Collected aerosols were evaluated using scanning electron microscopy and energy dispersive X-ray spectroscopy. Imaging revealed remarkable variations in aerosol morphology at the different workshops, and a presence of very large particles (up to≅100 × 50 μm 2 ) in the operator breathing zone. Characteristic X-ray analysis showed varying uranium weight percentages of aerosols and, frequently, traces of nitrogen, fluorine and iron. The analysis method, in combination with cascade impactor sampling, can be a powerful tool for characterization of aerosols. The uranium aerosol source term for risk assessment in nuclear fuel fabrication appears to be highly complex.

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“…It is known that the use of excess of hydrogen peroxide, the pH, the precipitation time and the temperature are importance known to be important in the production of uranium peroxide (Gupta et al, 2004;Kim et al, 2011). Therefore, in order to find optimal conditions for uranium stripping, the effects of the temperature, the concentrations of content of H 2 O 2 and NH 3 in the stripping solution, and the holding time of the phases were studied.…”

Section: Resultsmentioning

confidence: 99%

Uranium stripping from tri-n-butyl phosphate by hydrogen peroxide solutions

et al. 2013

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a b s t r a c t a r t i c l e i n f oThe processes of uranium stripping from 30% tri-n-butyl phosphate (TBP) in "odorless" kerosene by H 2 O 2 solutions both with and without NH 4 OH added were investigated in the temperature range of 20-50°C and with a volumetric ratio of 1 between the organic and aqueous phases. The uranium was selectively precipitated in the form of uranium peroxide during stripping from the organic phase by hydrogen peroxide. The stripping of uranium increased with increasing H 2 O 2 content, increasing temperature and increasing concentration of NH 3 in the range of 0-15 g/L. The use of a heated solution (40°C) that contained 4 mol H 2 O 2 /mol U and NH 3 12 g/L resulted in 99.7% of the uranium being stripped from TBP in the form of uranium peroxide. The uranium peroxide obtained by stripping is a highly pure product that exists in two different hydrated forms: UO 4 •4H 2 O (92 mass %) and UO 4 •2H 2 O. The mean particle diameter was 20.75 μm. The effect of hydrogen peroxide on the organic phase was studied by IR spectroscopy. No structural changes in TBP were observed after 30 cycles of extraction/stripping; thus, the use of hydrogen peroxide in this application is unrestricted.

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Effects of the different conditions of uranyl and hydrogen peroxide solutions on the behavior of the uranium peroxide precipitation

Cited by 65 publications

References 8 publications

Technique for recovering uranium from sludge-like uranium-bearing wastes using hydrochloric acid

Technique for recovering uranium from sludge-like uranium-bearing wastes using hydrochloric acid

Uranium aerosols at a nuclear fuel fabrication plant: Characterization using scanning electron microscopy and energy dispersive X-ray spectroscopy

Uranium stripping from tri-n-butyl phosphate by hydrogen peroxide solutions

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