نتایج جستجو برای: hematite and magnetite
تعداد نتایج: 16829021 فیلتر نتایج به سال:
Hematite fines were found to form aggregates with magnetite ~des in the same slurry, without the help of any flocculants. Because of this aggregation. fine iron ores containing hematite and -anetile can be successfully concentrated by multi-stage deslimings. ~ that the ore is finely ground and silicate gangues properly ~rsed. The effectiveness of this technique has been tested on a UMIIIIIercia...
This project serves as a literature review on the transformation and synthesis of magnetite from hematite under hydrothermal conditions as well as with Pulsed Laser Deposition (PLD) and milling. Magnetite forms over a similar range of elevated temperatures regardless the method that is used to synthesize it, including nonheterogeneous, loosely controlled environments such as a ceramics kiln. Ba...
The oxygen content of the atmosphere is thought to have increased in two steps: the Paleoproterozoic Great Oxidation Event and the Neoproterozoic Oxidation Event. The younger event is still a matter of debate (Och and Shields-Zhou, 2012). Macouin et al. (2015) suggest that it may have been triggered by volcanic degassing from unusually oxidized magmas occurring in a subduction ring surrounding ...
Iron ore occurrences are situated on the south-eastern slopes of the Medvednica Mountain. They occur as discontinous, decameters long and 2-3.5 m thick bedded, poorly mineralized (15-35 % Fe) lenses. A narrow, 6 km long, ore zone strikes NE-SW from Tisova Peć to Pustodol-Adolfovac. It is spatially and genetically bounded to the basic volcanogenic-sedimentary series (SEDEX-type), metamorphosed i...
[1] The Mössbauer (MB) spectrometer on Opportunity measured the Fe oxidation state, identified Fe-bearing phases, and measured relative abundances of Fe among those phases at Meridiani Planum, Mars. Eight Fe-bearing phases were identified: jarosite (K,Na,H3O)(Fe,Al)(OH)6(SO4)2, hematite, olivine, pyroxene, magnetite, nanophase ferric oxides (npOx), an unassigned ferric phase, and metallic Fe (k...
Control of Earth-like magnetic fields on the transformation of ferrihydrite to hematite and goethite
Hematite and goethite are the two most abundant iron oxides in natural environments. Their formation is controlled by multiple environmental factors; therefore, their relative concentration has been used widely to indicate climatic variations. In this study, we aimed to test whether hematite and goethite growth is influenced by ambient magnetic fields of Earth-like values. Ferrihydrite was aged...
An investigation was carried out aiming at assessing the potential of vis-NIR reflectance spectroscopy, through comparison with the conventional X-ray powder diffraction (XRPD) technique, for the characterization of synthetic gleys, obtained in laboratory starting from Fe0 and Fe2+ under different conditions of initial pH (5.5, 7.0 and 8.5). XRPD analysis showed that in any case goethite formed...
We analyze in this contribution the effect of aging on the electrokinetic properties of magnetite (Fe(3)O(4)) and hematite (alpha-Fe(2)O(3)). In both cases, high-purity commercial samples and monodisperse synthetic particles were studied. Commercial magnetite showed a rather erratic dependence of its electrophoretic mobility u(e) with the concentration of NaCl. Furthermore, sufficient concentra...
Fe(II) was added to U(VI)-spiked suspensions of hydrous ferric oxide (HFO) or hematite to compare the redox behaviors of uranium in the presence of two different Fe(III) (oxyhydr)oxides. Experiments were conducted with low or high initial sorption density of U(VI) and in the presence or absence of humic acid (HA). About 80% of U(VI) was reduced within 3 days for low sorbed U(VI) conditions, wit...
in this work, a bench-scale process was developed using mineral-processing methods to recover iron from a placer deposit located in bardaskan, khorasan-e-razavi, iran. the mineralogical studies were performed by x-ray diffraction (xrd), x-ray fluorescence (xrf), electron probe micro-analyzer (epma), and an optical microscope. these studies indicated that titanomagnetite, magnetite, and hematite...
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