Abstract:
BACKGROUND The Ordos Basin is one of the most important areas in China because it hosts lots of sandstone-type uranium deposits and a variety of other energy and mineral resources. The occurrence of uranium minerals is of great significance to the genetic understanding and prospecting of sandstone-type uranium deposits. However, the complex mineral composition, fine grain size, and various types and occurrences of uranium minerals make the initial identification stage of the study difficult. Currently, radiograph and electron probe microanalysis (EMPA) have played an important role in the identification of uranium minerals. Radiography can be used to obtain the position, occurrence and radioactive form of all uranium minerals in the light film at one time, but the mineral type cannot be identified. Moreover, it is a lengthy process and must be performed in darkness. Electron probe can be used to obtain the backscattered image of the uranium mineral. However, it takes time and effort to find uranium minerals with small content and small particle size in thin slices at high magnification, and it is impossible to quickly determine the types of associated minerals in BSE images.
OBJECTIVES To find a more rapid and accurate method for identifying uranium minerals.
METHODS The automatic mineral analysis system (AMICS), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used to identify minerals from sandstone-type uranium deposits in the north, south, and west margins of the Ordos Basin.
RESULTS The minerals in the study were identified as coffinite, pitchblende, uraninite and uranophane. Pyrite and titanium oxide were closely related to uranium minerals, and other associated minerals were identified as quartz, rutile, feldspar, mica and kaolinite.
CONCLUSIONS AMICS-SEM-EDS in situ analysis technology proves to be a reliable method for the rapid identification of uranium minerals, associated minerals, and their occurrences.
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