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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.
Hofrat en Nahas Cu-Au-U deposit, Sudan: Fluid inclusion evidence for a magmatic origin
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
Mineralization at HEN is composed of quartz, sulphide and calcite veins occupying late brittle fractures. Ore bodies are structurally controlled along shear zones and strike mainly NE (Fig. 1). They are 50 to 675 m long and 20 to 40 m thick and are crosscut by late-stage NW-striking faults on a mine scale (Fig. 1). Ore minerals are mainly composed of chalcopyrite and pyrite, with minor molybdenite and traces of uraninite and native gold. In the oxidation zone, the main copper secondary minerals are malachite and chrysocolla, while the main uranium mineral is torbernite (Master 1999). The ore reserves of the HEN deposit are some 20 Mt at 5.9% Cu. Associated with the copper is Au (up to 9 g/t), as well as U, Mo, Co, Ag, Pb and Zn (Binda et al. 1993). There is a strong positive correlation of Cu with Au and U (Master 1999).
Uranium isotopic ratio of black shale and its role in detection of oxic-anoxic conditions of uranium depositions
Published in Journal of Environmental Science and Health, Part A, 2022
Zainab Z. Al-Full, Mahmoud R. Khattab
Um bogma Formation was mostly precipitated in a shallow marine environment. After deposition, a period of intense rainfall prevailed, leading to the formation of caves (karstification), channels, lagoons and marginal basins, followed by arid to semi-arid climatic conditions leading to the formation of fluvial and lacustrine deposits. These deposits filled the earlier channels, lagoons and basins to produce the paleochannels with carbonaceous shale, rounded dolostone remnants, and several sandstone fragments within those channels. Um Bogma Formation hosting the organic matters is the most responsible zone for radioactive and heavy metals mineralization.[29,40–42] Uranium is concentrated along many local normal faults striking NNW-SSF in areas where organic matter and framboidal pyrite are present, suggesting the role of microorganisms in oxic-anoxic conditions. The environment was reducing, as illustrated by the presence of sulfides and carbonaceous materials. Accordingly, a redox zone is developed and can be located at the interface between the oxidation and reduction zones. The reduced material contains coffinite and uraninite, which are typically intimately mixed with a carbonaceous matter, pyrite, and barite. The ore body is partly oxidized and the oxidized zone contains hexavalent uranium minerals, including torbernite, uanophane and sklodowskite.[29,41,42]
U–Pb geochronology reveals evidence of a Late Devonian hydrothermal event, and protracted hydrothermal–epithermal system, within the Mount Painter Inlier, northern Flinders Ranges, South Australia
Published in Australian Journal of Earth Sciences, 2020
S. B. Hore, S. M. Hill, A. Reid, B. Wade, N. F. Alley, D. R. Mason
A number of these unmetamorphosed sedimentary outcrops of the RRB are highly radioactive. Some contain uranium-bearing minerals such as uraninite, and secondary minerals such as torbernite. Primary mineralisation is associated with the intrusion of Fe ± Mn ± U-rich fluids above the fractured or in-situ brecciated Meso-proterozoic basement and deposited within the glacial sediments.