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Minerals of radioactive metals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Uranium occurs in nature in low concentrations in soil, rock and water. Uranium-bearing minerals such as uraninite UO2 [766], carnotite, autunite, uranophane, torbernite and cof-finite are the commercial sources of the metal. It also occurs in some substances such as phosphate rock deposits, and in minerals such as lignite and monazite sands. Uranium(VI) forms highly soluble carbonate complexes at alkaline pH leading to an increase in mobility and availability of uranium to groundwater and soil from nuclear waste [767].
Fluoride, uranium and arsenic: occurrence, mobility, chemistry, human health impacts and concerns
Published in Alberto Figoli, Jan Hoinkis, Jochen Bundschuh, Membrane Technologies for Water Treatment: Removal of Toxic Trace Elements with Emphasis on Arsenic, Fluoride and Uranium, 2016
Alberto Figoli, Jochen Bundschuh, Jan Hoinkis
The sources of U are commonly known minerals such as uraninite (UO2) and pitch blend (U3O8); though other minerals such as carnotite, autunite, uranophane, torbernite, and coffinite also contain U. Secondary sources of Uinclude phosphatic rocks and minerals such as lignite and monazite. Estimated U deposit in phosphatic rocks (world average U content in phosphate rock is estimated at 50–200 mg kg−1) is about 9 million tons (http://www.wise-uranium.org/uod.html). The U recovery from the minerals involves acid (using dilute sulfuric acid) or alkaline (using sodium carbonate) leaching followed by solvent extraction methods using D2EHPA (di−2-ethylhexylphosphoric acid) and tri-alkyl amines which are well known as the DAPEX (dialkylphosphoric acid extraction) and AMEX (amine extraction) processes, respectively. Uranium produced through these processes is further purified to obtain nuclear-grade U by a solvent extraction method from a nitric acid medium using TBP (tri-n-butyl phosphate) in kerosene as the extractant.
Nuclear Fuel Resources
Published in Kenneth D. Kok, Nuclear Engineering Handbook, 2016
A large variety of secondary uranium minerals are known, many are brilliantly colored and fluorescent. The commonest are gummite (a general term like limonite for mixtures of various secondary hydrated uranium oxides with impurities); hydrated uranium phosphates of the phosphuranylite type, including autunite (with calcium), saleeite (magnesium), and torbernite (with copper); and hydrated uranium silicates such as coffinite, uranophane (with calcium), and sklodowskite (magnesium).
Mine-site derived particulate matter exposure exacerbates neurological and pulmonary inflammatory outcomes in an autoimmune mouse model
Published in Journal of Toxicology and Environmental Health, Part A, 2021
Alexis Wilson, Carmen A. Velasco, Guy W. Herbert, Selita N. Lucas, Bethany N. Sanchez, José M. Cerrato, Michael Spilde, Quan-Zhen Li, Matthew J. Campen, Katherine E. Zychowski
The XRF analysis conducted on the Saint Anthony mine samples detected 2.32% U by weight, and ICP analyses for the acid digestions detected 1.13% U by weight. Electron probe microanalysis shows the association of U-Ca-P which is consistent with the stoichiometry of autunite [Ca(UO₂)₂(PO₄)₂·10–12 H₂O]. The U-P phases found in this sample was observed at other sites of the Jackpile Sandstone Member of the Morrison formation (Avasarala et al. 2019; Blake et al. 2017). In addition, these analyses also indicate areas with significant content of Si. Other investigators detected the mineral coffinite [USiO4] in samples from this formation (Avasarala et al. 2017; Blake et al. 2017; Deditius, Utsunomiya, and Ewing 2008). Our findings showed 19.69 ± 1.04% mass loss by LOI and 19.85 ± 0.79% by TGA due to volatilization of NOM. Previous investigations conducted by our research group found similar results in samples from the Jackpile Sandstone Member of the Morrison Formation (Ruiz, Thomson, and Cerrato 2016; Velasco et al. 2019). The mineralogy of these samples is complicated given the high content of organic matter and co-occurrence of various U-bearing phases.