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- Author or Editor: V. Domocoş x
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Abstract
The chemical analysis of hydrated uranium tetrafluoride is described. This product was obtained in a wet process. Several methods were taken into account and applied to this product. In the case of uranium the following techniques were employed: isotope dilution with mass spectrometry, X-ray fluorescence, volumetric measurements, spectrophotometry, Volkovs's method, natural radioactivity measurements using the 185 keV235U peak and neuton activation analysis. In the case of fluoride determination, four methods gave good results. An explanation is given for a discrepancy appearing in one case. Free water in the product was determined in the classical way at 105 °C, with the Karl Fischer reagent and by thermogravimetric analysis. Hydration water was also estimated from thermogravimetric determinations in nitrogen to avoid product oxidation. Thus the formula UF42·2H2O was found. Other impurities were determined by emission spectroscopy, mass spectrometry, neutron activation and chemical analysis.
Abstract
In order to determine uranium from raw phosphoric acid solutions, resulted by the sulphuric acid attack of phosphate rocks and the strip solutions of the solvent extraction process for uranium recovery, two classes of analytical methods were established: one for low uranium content in phosphoric acid, and the other for higher uranium concentration in the same medium. The study was based on specific methods, therefore interference probability with other impurities in phosphoric acid medium is low. In the first class, X-ray fluorescence and spectrophotocolorimetric methods were used. X-ray fluorescence was applied on direct raw phosphoric acid solution and raffinate. The last one was associated with solvent extraction [di-(2-ethylhexyl) phosphate + triocylphosphine oxide] on the U(IV)-Arsenazo III complex in strip. The methods of the second class, were used for strip uranium concentrated solutions: X-ray fluorescence isotopic dilution and mass spectrometry, spectrophotocolorimetry and activation analysis associated with gamma-spectrometry. Here spectrophotocolorimetry involves two methods. The first one is based on the U(IV)-Arsenazo III complex and the other on direct U(IV)—phosphoric acid solutions measurements. A good agreement was obtained in each case for all comparative measurements involving various methods.
