Authigenic magnetite formation from goethite and hematite
2018年3月8日 Authigenic magnetite formed from microcrystalline goethite and hematite dominantly behaves as interacting single-domain particles, while nanophase goethite
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Characterization of hematite (α‐Fe2O3), goethite
2006年12月16日 The presence of hematite grains with different provenance (e.g., detrital and authigenic) would therefore compromise
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Comparison of magnetite, hematite and goethite
2023年4月25日 The adsorption of phosphate onto magnetite, hematite and goethite mainly obeyed the inner-sphere complexation mechanism, and the phosphate adsorption
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Production and in situ transformation of hematite into magnetite
2019年8月5日 The transformation of hematite to magnetite occurs at 623 K (for biomass/nitrate mixture) and 723 K (for biomass/goethite mixture). The formation of
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Morphology‐Dependent Magnetic Properties in
2 天之前 This might suggest a combination of partially oxidized magnetite and goethite, where the contribution from goethite increases as the separation of the curves increase
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Bulk and key surface structures of hematite, magnetite, and goethite
2009年10月1日 Abstract. The iron oxides hematite, magnetite, and goethite were studied with density functional theory to establish a consistent set of structures for both the bulk
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Control of Earth-like magnetic fields on the transformation
2016年7月26日 For fields below ~60 μT, hematite and goethite coexist. In contrast, above 60 μT, hematite is dominant and goethite is undetectable. Based on XRD results, we
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Control of Earth-like magnetic fields on the transformation
2016年7月26日 Chicot, D. et al. Mechanical properties of magnetite (Fe3O4), hematite (α-Fe2O3) and goethite (α-FeOOH) by instrumented indentation and molecular dynamics analysis. Mater. Chem.
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Arsenic sorption onto natural hematite, magnetite, and goethite
2007年3月22日 A high sorption of both As (III) and As (V) on magnetite was observed by Parga et al. [19] when removing arsenic from a Mexican contaminated groundwater by using electrocoagulation. In this work, we have tested the sorption of arsenic on natural magnetite, hematite, and goethite in order to compare the sorption capacity of these minerals with ...
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Heated goethite and natural hematite: Can Raman
2007年11月20日 The chemical species involved in the present investigation are goethite, hematite and magnetite, since there are some reports in the literature suggesting the formation of magnetite when goethite is heated at temperatures close to 300 °C [22].These compounds are easily differentiated by their Raman spectra (Fig. 1 and Table 1), what
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Bulk and key surface structures of hematite, magnetite, and goethite
2009年10月1日 The iron oxides hematite, magnetite, and goethite were studied with density functional theory to establish a consistent set of structures for both the bulk mineral and key surfaces, characterize surface relaxation, and predict and test calculated scanning tunneling microscopy (STM) images. Spin-polarized, plane-wave pseudopotential
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Magnetism of Al‐substituted magnetite reduced from Al‐hematite
2016年6月7日 For example, a fire can heat the topmost centimeters of soil to 800°C and cause a reducing soil-pore atmosphere, e.g., CO and CO 2 [Tunstall et al., 1976; Haliuc et al., 2016], which results in transformation of hematite and/or goethite to magnetite [Swann and Tighe, 1977; Zhang et al., 2012; Jiang et al., 2015].
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Goethite Iron Oxide, Hematite, Limonite Britannica
Goethite is normally formed under oxidizing conditions as a weathering product of iron minerals (e.g., pyrite, magnetite). Because it is formed near the surface, goethite is the major component of the gossan of iron sulfide deposits in locations such as Arizona and of lateritic deposits in places such as Cuba.
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Arsenic (V) adsorption from aqueous solution onto goethite, hematite ...
2011年10月17日 Highlights Hematite, goethite, zero-valent iron and magnetite were used to remove As(V). Hematite is a suitable adsorbent over wide ranges of pH and As(V) concentrations. Arsenate adsorption isotherms are well fitted with the Langmuir model. Adsorption capacity is related to the iron content of adsorbents. Arsenate desorption from
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Kinetics of hematite to magnetite transformation by gaseous
2019年8月1日 The transformation of weakly magnetic hematite to magnetite is a promising technique that can enhance the efficiency of magnetic separation of hematite quartzite. The transformation of hematite into magnetite involves the partial reduction of Fe(III) to Fe(II) and converting the rhombohedral crystal system of hematite into cubic of magnetite.
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Sorption of silicates on goethite, hematite, and magnetite:
2007年8月15日 Sorption of H 4 SiO 4 (including experiments as a function of time, K d measurement with different m / v ratios and sorption edges) onto different iron (hydro)oxides as goethite (α-FeOOH), hematite (α-Fe 2 O 3), and magnetite (Fe 3 O 4) has been studied with concentration of silicates under solubility limit.A surface complexation model has
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Thermal treatment of natural goethite: Thermal transformation and ...
2013年9月20日 1. Introduction. Goethite, α-FeOOH, is widely distributed, occurs in rocks, soils and throughout the global ecosystem, and has the diaspore structure which is based on hexagonal close packing [1].Generally, goethite is an oxidation, decomposition, weathering and hydrolyzation product of pyrite, siderite, magnetite and Fe-containing silicates [1]. ...
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The preparation of magnetite, goethite, hematite and maghemite
2007年1月1日 Magnetite and goethite were precipitated from their respective precursors in aqueous media. Various red shades of hematite were prepared by the calcinations of the precipitated goethite at temperatures ranging from 600 to 900 °C. Maghemite was obtained by thermal treatment of magnetite at 200 °C.
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Arsenic sorption onto natural hematite, magnetite, and goethite
2007年4月1日 In other studied on porous hematite. pHPZC also measured at level of 6 (Singh and Pant 2004) and the pHPZC are: magnetite 6.5; goethite, 6.8; hematite, 6.7 (Giménez et al. 2007; Kosmulski 2014). ...
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(PDF) Mineral and Magnetic Transformations of Goethite-Hematite
2022年12月17日 magnetite. For goethite-hematite, the maximum values of magnetization above 60 Am 2 /kg were . observed for the samples roasted at 600-700 °C with the resulting c ontent of magnetite also higher .
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On the goethite to hematite phase transformation - Springer
2010年4月13日 From goethite to hematite: thermoanalytical aspects. The DTA curves in Fig. 1 display, as more intense endothermic peaks, those pertaining to the phase transition from goethite to hematite, occurring during the first heating run of the two goethite materials (SA and GS). This irreversible transformation occurs, as expected [3, 6, 7, 11–14], over a
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Understanding the effects of goethitic iron ore – Process productivity
Compared with hematite and magnetite, goethite has a much more diverse range of textural forms and occurrences, and its influence on iron ore processing is less understood. Currently, most analysis of the effects of goethite on mine performance considers only the chemistry of the ore and not its textural components. Through improved textural ...
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Heterogeneous reaction of NO2 with hematite, goethite and magnetite ...
2020年3月1日 The iron fractional solubility for unreacted hematite, magnetite and goethite were found to be approximately in the range of (1-10) × 10 −5. After heterogeneous reaction with 2.5 ± 0.1 ppmv NO 2 for 24 h, the increase in iron fractional solubilities was very small and in some cases even insignificant. To our ...
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Replacement of magnetite by hematite in hydrothermal systems
2022年1月1日 In the BSY-1 foil, hematite nanocrystals were identified by electron diffraction patterns in large pores (Fig. 2).Although some of them have an acicular morphology with a width up to 5 nm, no d-spacings of goethite can be found and indexed in the diffraction patterns (Fig. 2 d).The rest consists of island-like hematite nanocrystals
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Bulk and key surface structures of hematite, magnetite, and goethite
2009年10月2日 The iron oxides hematite, magnetite, and goethite were studied with density functional theory to establish a consistent set of structures for both the bulk mineral and key surfaces, characterize ...
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A promising process for transformation of hematite to magnetite
2020年9月1日 Regular companions of alumina in the feedstock derivatives are iron-containing minerals, the main of which – hematite α-Fe 2 O 3 and magnetite Fe 3 O 4 – change little if at all in the technological process, while goethite α-FеООН, maghemite γ-Fе 2 O 3, and siderite FеСO 3 transform to stable hematite.
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