کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
233607 465353 2012 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Chemical and microstructural characterisation studies on natural and heat treated brannerite samples
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Chemical and microstructural characterisation studies on natural and heat treated brannerite samples
چکیده انگلیسی

Two naturally occurring brannerite samples from the Crockers Well and Roxby Downs deposits in South Australia were characterised to assess their compositional, mineralogical, and textural properties. Characterisation was undertaken using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Raman Spectroscopy and an Electron Probe Micro-analysis (EPMA). The samples were also heat treated to examine the effect of temperature on recrystallisation, mineral stability and deportment of impurities. In each sample, the brannerite was found to be thorium-rich (∼8–10 wt.% Th) indicating partial solid solution between brannerite and thorutite (ThTi2O6). Other minerals identified in the samples were thorutite (ThTi2O6), uranothorite ([Th, U]SiO4), a thorianite–uraninite solid solution ([Th, U]O2) and gangue minerals including rutile, quartz, aluminosilicates, zircon, titanite, apatite and unidentified REE-containing phosphates. The brannerite in both samples was amorphous having undergone radiation-induced metamictisation. Crystallinity of the brannerite was restored upon heating of the samples to 1200 °C for 24 h in air. For the Crockers Well sample, radiation damage annealing/recrystallisation began at temperatures as low as 800 °C while the Roxby Downs sample did not begin to show evidence for recrystallisation until 900 °C. The main mineralogical changes after heating and recrystallisation involved a decrease in the amount of thorianite-uraninite phase due to decomposition into ThO2 and UO2 as well as the formation of Pb-rich glass films at grain boundaries. Compositional, textural and microstructural aspects of brannerite are likely to play an important role in any process to extract uranium from brannerite-containing ores.


► Chemical and microstructural features of natural brannerite containing samples.
► Raman data for metamict and non-metamict natural brannerite bearing samples.
► Composition/microstructure studies on metamict brannerite heated at 1,100 °C.
► Identification of gangue minerals associated with brannerite.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Minerals Engineering - Volume 39, December 2012, Pages 276–288
نویسندگان
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