scholarly journals Improved Uranium Recovery from the Process Streams in an Electroplating Facility

1984 ◽  
Vol 44 ◽  
Author(s):  
John B. Pickett
Keyword(s):  
Phosphoric Acid ◽  
Current Level ◽  
Ion Concentration ◽  
Caustic Solution ◽  
Acid Solutions ◽  
Savannah River ◽  
Uranium Recovery ◽  
Phosphate Ion ◽  
Savannah River Plant ◽  
Uranyl Phosphate

AbstractCylindrical uranium slugs are used as irradiation targets in the production reactors at the Savannah River Plant. These slugs are first chemically etched, nickel plated, encased in aluminum, inspected, and individually pressure tested. An improved process was developed to recover the uranium from the acidic etching streams by controlling pH and the PO4 to U ratio so that the precipitation of the uranium as hydrogen uranyl phosphate was maximized. Bench scale tests demonstrated that the recovery of uranium could be increased to greater than 99.9% (vs. the current level of about 95% recovery). The recommended changes involved the addition of process effluent “hold” tanks. The addition of the various process streams to the neutralization/precipitation tank could therefore be controlled to maintain a consistent ratio of uranyl nitrate and phosphoric acid. Also, it was determined that a strong caustic solution (resulting from the dissolution of rejected aluminum slugs) could be utilized to neutralize the nitric and phosphoric acid solutions. The buffering action of the aluminum in the “caustic recovery solution” would reduce the sensitivity of the hydrogen uranyl phosphate precipitation to the phosphate ion concentration.

scholarly journals Kinetics of pyrite oxidation by hydrogen peroxide in phosphoric acid solutions

1999 ◽  
Vol 64 (12) ◽  
pp. 753-764 ◽  
Author(s):  
Mile Dimitrijevic ◽  
Milan Antonijevic ◽  
Valentina Dimitrijevic
Keyword(s):  
Hydrogen Peroxide ◽  
Phosphoric Acid ◽  
Pyrite Oxidation ◽  
Negative Influence ◽  
Acid Solutions ◽  
Phosphate Ion ◽  
Shrinking Core ◽  
Kinetics Of ◽  
Rate Controlling Step ◽  
Oxidation By Hydrogen Peroxide

The kinetics of pyrite oxidation by hydrogen peroxide in phosphoric acid solutions were investigated. The effects of stirring, temperature, and particle size, as well as of the hydrogen peroxide and phosphoric acid concentrations were studied. The effect of phosphate ion addition was also examined. The oxidation kinetics was found to follow a shrinking core model, with the surface chemical reaciton as the rate-controlling step. This is in accord with an activation energy of 57 kJ/mol and a linear relationship between the rate constant and the reciprocal of the particle radius. The reaction order with respect to the hydrogen peroxide concentration was found to be equal to unity. Variation of the phosphoric acid concentration had practically no effect on the rate of pyrite oxidation. Addition of the phosphate ion in the relatively low concentration range (0.005.0.1 mol/dm 3) had a highly negative influence on the rate of pyrite oxidation, indicating that this ion has an inhibiting effect on the oxidation of pyrite by hydrogen peroxide.

Fluctuations of Annual Precipitation and Water Resources Quality in Ukraine

2016 ◽  
Vol 10 (4s) ◽  
pp. 621-629
Author(s):  
Valentina Pidlisnyuk ◽  
◽  
John Harrington JR ◽  
Yulia Melnyk ◽  
Yuliya Vystavna ◽  
...  
Keyword(s):  
Water Resources ◽  
Surface Waters ◽  
Precipitation Amount ◽  
Ion Concentration ◽  
Annual Precipitation ◽  
Resource Quality ◽  
Phosphate Ion ◽  
Regional Trends

The article focuses on examining the influence of fluctuations in annual precipitation amount on the quality of surface waters. Water quality was estimated with data on BOD, COD and phosphate–ion concentration within five selected regions of Ukraine. Analysis of the precipitation data (1991 – 2010) showed different regional trends. Using the statistics, determination of the interconnection between precipitation amount and water resources quality were done. The obtained regularities and associated uncertainties can be used for prediction of changes in water resource quality and as a guide for future adaptation to possible climate change.

scholarly journals Photochemical Reactions of Uranium(VI) in Aqueous Phosphoric Acid Solutions

1991 ◽  
Vol 28 (5) ◽  
pp. 418-425 ◽  
Author(s):  
Yoon-Yul PARK ◽  
Masayuki HARADA ◽  
Hiroshi TOMIYASU ◽  
Yasuhisa IKEDA
Keyword(s):  
Phosphoric Acid ◽  
Photochemical Reactions ◽  
Acid Solutions

Physical Properties of Saltstone: Physical Properties of Saltstone: A Savannah River Plant Waste Form

1984 ◽  
Vol 44 ◽  
Author(s):  
Christine A. Langton
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Field Tests ◽  
Waste Form ◽  
Savannah River ◽  
X Ray Diffraction ◽  
Near Surface ◽  
Leach Rate ◽  
Savannah River Plant ◽  
Water To Cement Ratio

AbstractA cement-based waste form, “saltstone,” has been designed for disposal of Savannah River Plant low-level radioactive salt waste. Laboratory and field tests indicate that this stabilization process greatly reduces the mobility of all of the waste constituents in the surface and near-surface environment. Bulk properties of this material have been tailored with respect to salt leach rate, permeability, and compressive strength. Microstructure and mineralogy were characterized by SEM and x-ray diffraction analyses.Compressive strength was found to increase as the water to cement ratio decreased. Porosity and mean pore size increased with increasing water to cement ratios. Bulk diffusivities of the various ions dissolved in the pore solutions were also found to increase as water to cement ratios increased.

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