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

Journal of earth system science

Pragya Pandit^1¹  Shailendra Kumar^1²  Rohit Mehra^2³  Pargin Bangotra^2⁴ 

[1] Atomic Minerals Directorate for Exploration and Research, New Delhi 110 066, India.^1;Dr. B.R. Ambedkar National Institute of Technology, Jalandhar 144 011, India.^2;Maharaja Surajmal Institute of Technology, USICT, GGSIPU, New Delhi 110 058, India.^4;Radiochemistry Division, Bhabha Atomic Research Center, Mumbai 400 085, India.^3

关键词: Uranium;    photoluminescence;    X-ray absorption spectroscopy;    X-ray diffraction;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

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 ($\alpha$-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 $\mu$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.

【 授权许可】

CC BY