Influence of microwaves on the leaching kinetics of uraninite from a low grade ore in dilute sulfuric acid

•U leaching from a low-grade Si-rich ore studied in H2SO4 medium with (MW) irradiation.•MW heating is more efficient in terms of U recovery, kinetics and purity of liquor.•U leachability of 84% obtained in 90min at 95°C with 0.38M H2SO4 at 450mVwith MW heating•Conventional conductive heating gave ab...

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Bibliographic Details
Published in:Journal of hazardous materials 2016-08, Vol.313, p.9-17
Main Authors: Madakkaruppan, V., Pius, Anitha, T., Sreenivas, Giri, Nitai, Sarbajna, Chanchal
Format: Article
Language:English
Subjects:
Acid leaching
Aluminum
Diffusion layers
Dissolution
Leach kinetics
Leaching
Microwaves
Rock
Sulfuric acid
Uranium
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Summary:•U leaching from a low-grade Si-rich ore studied in H2SO4 medium with (MW) irradiation.•MW heating is more efficient in terms of U recovery, kinetics and purity of liquor.•U leachability of 84% obtained in 90min at 95°C with 0.38M H2SO4 at 450mVwith MW heating•Conventional conductive heating gave about 74% leachability with less purity liquor.•U leaching was found follow product layer diffusion as controlling mechanism. This paper describes a study on microwave assisted leaching of uranium from a low-grade ore of Indian origin. The host rock for uranium mineralization is chlorite-biotite-muscovite-quartzo-feldspathic schist. The dominant presence of siliceous minerals determined leaching of uranium values in sulfuric acid medium under oxidizing conditions. Process parametric studies like the effect of sulfuric acid concentration (0.12–0.50M), redox potential (400–500mV), particle size (600–300μm) and temperature (35°–95°C) indicated that microwave assisted leaching is more efficient in terms of overall uranium dissolution, kinetics and provide relatively less impurities (Si, Al, Mg and Fe) in the leach liquor compared to conventional conductive leaching. The kinetics of leaching followed shrinking core model with product layer diffusion as controlling mechanism.
ISSN:0304-3894
1873-3336
DOI:10.1016/j.jhazmat.2016.03.050