Structural and luminescent characterisation of uraniferous fluorapatite and haematite associated with phosphatic rocks of the Bijawar group in Sagar District, Madhya Pradesh (India)

• Published in: Journal of Earth System Science 2018-12, Vol.127 (8), p.1-16, Article 110
• Main Authors: Pandit, Pragya, Kumar, Shailendra, Bangotra, Pargin, Mehra, Rohit, Mohapatra, Manoj, Roy, Madhuparna, Singh, A K
• Format: Article
• Language: English
• Subjects: Analytical methods; Calcium; Calcium ions; Charge transfer; Crystal structure; Earth and Environmental Science; Earth Sciences; Emissions; Ferric oxide; Fluorapatite; Fourier transforms; Haematite; Hematite; Investigations; Iron; Minerals; Near ultraviolet radiation; Oxidation; Phosphates; Photoluminescence; Photons; Quartz; Rocks; Scanning electron microscopy; Sedimentary rocks; Sediments; Sensors; Shale; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Species; Spectroscopic analysis; Spectroscopy; Spectrum analysis; Structural analysis; Ultraviolet radiation; Uranium; Valence; X ray absorption
• ISSN: 0253-4126; 0973-774X
• DOI: 10.1007/s12040-018-1009-1

The structural and spectroscopic characteristics of phosphatic ferruginous shale samples from the Bijawar Group rocks from Sagar District of Madhya Pradesh (India) have been probed for identification of uranium species. Fluorapatite ( Ca 5 (PO 4 ) 3 F , FAP) and haematite ( α - Fe 2 O 3 ) were identified as the main phases in the separated mineral concentrates. The photoluminescence (PL) and X-ray absorption near edge spectroscopy (XANES) studies pointed to a strong experimental evidence of both U(IV) and U(VI) oxidation states in the mineral concentrate portion obtained from the same parent host rock. The PL spectrum has confirmed the charge transfer (f–d) transition bands in UV and near-UV regions with emission peaks at ca. 290, 313, 336, 399 and 416 nm, which has been attributed to the substitution of Ca 2 + ions by U(IV) in FAP and broad structureless emission due to stabilisation of U(VI) as UO 6 6 - in haematite. Time-resolved spectroscopy studies have revealed biexponential decay components lasting 2–5 ns for U(IV) species and 10 μ s for U(VI) species. These characterisations revealed the fundamental information about the oxidation state and form of uranium in this region. Remediation measures for the Bijawar region are also suggested.