Mineralogical and Microchemical Methods for the Characterization of High-Grade Banded Iron Formation-Derived Iron Ore

A range of techniques has been applied to the mineralogical and microchemical characterization of high-grade iron ore hosted by banded iron formation (BIF), including reflectance spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscope, electron microprobe, and proton induced X-ray emission analysis (PIXE). These tools provide key physicochemical properties of the main ore minerals, such as magnetite, kenomagnetite, maghemite, hematite, and goethite, which in turn determine the grade of the deposit and its economic viability. For instance, current automated HyLogging (TM) systems, based on reflectance spectroscopy, provide quick and objective measurements of hematite, goethite, and gangue mineralogy on large volume of cores and drill chips. X-ray diffraction used on powders offers a full account of the bulk mineralogy of the sample as well as aluminum substitution in the structure of hematite goethite, and maghemite. On the other hand, Raman spectroscopy provides in situ iron oxide mineralogy and cation substitution at the thin section scale. In situ microchemical analyses, using scanning electron microscopy, electron microprobe, and PIXE, emphasize the mineralogical relationship and distribution of deleterious elements such as P, Al, and Si that underpins the development of downstream processing methods; for assessing upgradability and exploitation of iron ore deposits.