Magnesioferrita e caminho pedogenético de transformação de óxidos de ferro magnéticos em dois perfis de solo derivados de tufito da região do Alto Paranaíba (MG)

Silva, Fernando Dias da; Couceiro, Paulo Rogério da Costa; Fabris, José Domingos; Goulart, A. T.; Ker, João Carlos

doi:10.1590/s0100-06832005000500012

Cited by 4 publications

(5 citation statements)

References 21 publications

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“…Although many synthesis approaches have been developed, the natural magnesioferrite (MgFe 2 O 4 ) mineral has rarely been found. To the best of the author's knowledge, it has been identified in soils from the Alto Paranaíba region, State of Minas Gerais, Brazil [26,27] and in Victorian Brown Coal Fly Ash from the Latrobe Valley, Australia [28]. Magnesioferrite is known to be an important magnetic oxide with a spinel structure, with a widespread application in microwave devices due to their low magnetic, dielectric losses and high resistivity.…”

Section: Discussionmentioning

confidence: 99%

Magnetic Properties of Iron Sand from the Tor River Estuary, Sarmi, Papua

2018

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Information about the strategic mineral balance, published in 2013, presumed a significant amount of iron sand deposited in Sarmi, Papua, Indonesia. However, the magnetic properties of these iron sands have never been studied. Our preliminary study on the distribution of magnetic susceptibility of iron sand from the Sarmi Coast area has revealed that the iron sand from the Tor River estuary had the highest mass-specific magnetic susceptibility values with an χ LF average of 3.083 ×10 −5 m 3 /kg. We extracted the raw sand from the Tor River estuary using a mechanical magnetic extraction method and analyzed the magnetic properties and mineral composition. The magnetic susceptibility values increased significantly with an χ LF average of 27.496 ×10 −5 m 3 /kg. The chemical composition acquired from both the X-ray fluorescence and energy dispersive spectroscopy confirmed that the magnetic properties of the extracted sample originated from the high percentage of iron oxide. The hysteresis curve showed high saturation magnetization about 24.7 (emu/g), remanent magnetization of about 6.1 (emu/g) and a low coercive field of about 20 (Oe). The X-ray diffraction patterns identified a magnesioferrite (MgFe 2 O 4) mineral structure. This result showed the novelty of iron sand from Sarmi, Papua when compared with that from Java Island.

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Section: Discussionmentioning

confidence: 99%

Magnetic Properties of Iron Sand from the Tor River Estuary, Sarmi, Papua

2018

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“…Maghemite (ferromagnetic Fe oxide -Mh) occurred in all soils, even if virtually inexpressive in LVA 1 and LV 6 ( Table 1). In Brazil, for soils developed from mafic rocks, Mh formation is more associated with magnetite oxidation inherited from the parent material (Curi and Franzmeier, 1987;Fontes and Weed, 1991) as well as transformation from other magnetic phases, such as magnesiumferrite commonly found in tuffite and in the sand fraction of soils originating from it (Fabris et al, 1997b;Silva et al, 2005). However, under conditions of redox oscillations that occur during the wetting and drying cycles, fine magnetite grains may also be formed and subsequently oxidized, giving rise to Mh (Maxbauer et al, 2016).…”

Section: Mineralogical Composition Of the Clay Fractionmentioning

confidence: 99%

“…Although several studies have been conducted on Fe oxides in Brazil, few were able to gather a significant volume of soils originating from different parent materials with taxonomic similarities to the Brazilian (SiBCS - Santos et al, 2013) and North American (Soil Survey Staff, 2014) Classification Systems. The Fe-rich Rhodic Oxisols (Soil Survey Staff, 2014) occupy significant areas in the regions of the Central Plateau and the Ferriferous Quadrilateral in Brazil, especially those developed from basalt, tuffite, and itabirite, where, in addition to dystrophic and acric properties, typically feature high Rev Bras Cienc Solo 2017;41:e0160379 saturation magnetization, although with differences between soils developed from the same parent material (Carmo et al, 1984;Ferreira et al, 1994;Fabris et al, 1997a;Costa et al, 1999;Silva et al, 2005;Silva et al, 2010;Cervi et al, 2014;Costa et al, 2014;Carvalho Filho et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Pedogenic Iron Oxides in Iron-Rich Oxisols Developed from Mafic Rocks

Camêlo

Ker

Fontes

et al. 2017

Rev. Bras. Ciênc. Solo

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Despite the considerable amount of information on the mineralogical characteristics of pedogenic Fe oxides in Brazilian soils, there are few studies on Fe-rich soils developed from mafic rocks with taxonomic identities at lower categorical levels. This study evaluated the mineralogical characteristics of pedogenic Fe oxides in B horizons (Bw) of Fe-rich Oxisols developed from several mafic rocks in the state of Minas Gerais, Brazil. The Bw horizons were sampled at a 0.8-1.0 m depth in 13 Ferric and Perferric Rhodic Oxisols along with a Mesoferric Typic Oxisol originating from basalt, gabbro, tuffite, amphibolite and itabirite in Minas Gerais. The selected soils have taxonomic identities up to the fourth categorical level of the Brazilian System of Soil Classification. In the laboratory, the following analyses were made: a) powder X ray diffraction (XRD) of the clay fraction before and after selective concentration of Fe oxides by silicate alkaline dissolution (5 mol L-1 NaOH); b) selective chemical dissolution of the clay fraction by citrate-bicarbonate-dithionite (CBD), acid ammonium oxalate (AAO), and sulfuric acid (H 2 SO 4 1.8 mol L-1); c) quantitative estimation of minerals in the clay fraction through allocation of phases from the XRD patterns, magnetic susceptibility of the clay fraction, and quantification of elements after sulfuric acid digestion (H 2 SO 4 1:1) of the air-dried fine earth and treatment of the clay fraction with CBD; and d) estimation of the mean crystal size (MCS), specific surface area (SSA), and isomorphic Al-substitution (IS) of hematite, goethite, and maghemite from the XRD patterns obtained from concentrates of Fe oxides. The results showed that estimation of Fe content of maghemite by selective dissolution with 1.8 mol L-1 H 2 SO 4 may not be accurate enough to realistically reflect the maghemite contents in the soil sample. The Al content extracted may also be influenced by other minerals that are sources of this element. Hematite crystals were predominantly placoid in shape in all Rhodic Oxisols and had smaller SSA compared to goethite, which showed both isodimensional and asymmetric habit. Higher crystallinity of maghemite and the IS values generally lower than those of hematite and goethite suggest that in well-drained soils derived from mafic rocks, the IS phenomenon in maghemites seems to result from pedogenetic advancement after its formation from magnetite oxidation.

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“…A magnetita é muito estudada por sua importância econômica na indústria eletrônica (produção de cabeça reprodutora de som e vídeo, e de disquetes) e por ser um mineral acessório de inúmeras rochas, máficas, como basalto 1,2 , anfibolito 3 e tufito 4,5 , e não-máfica, como esteatito 6,7 (pedra-sabão). Na literatura, são relatados diversos caminhos de síntese de Fe 3 O 4 , como: hidrólise alcalina de solução de sulfato ferroso, para gerar Fe(OH) 2 seguida por aquecimento do produto a 100 o C (reação de Schikorr) 8 ; redução de hematita a 400 o C em atmosfera de 5% H 2 e 95% de ar, saturada com vapor de água e livre de oxigê-nio 9 ; transformação redutiva em uma ampola lacrada de uma suspensão de akaganeíta na presença de hidrazina em pH 9,5-11,5 e 100 o C 10 e aquecimento de hidróxido acetato de ferro amorfo em atmosfera inerte de N 2…”

Section: Introductionunclassified

Uma estratégia adaptada para síntese de magnetita

Santana¹,

Ramos²,

Fabris³

2008

Quím. Nova

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Recebido em 3/1/07; aceito em 19/7/07; publicado na web em 19/12/07 AN ADAPTED MAGNETITE SYNTHESIS STRATEGY. Chemical reactions in the solid state are often not included in undergraduate chemistry curricula, due to requirements for special laboratory facilities such as ovens and precision weighing balances. This work aims to describe novel and relatively simple magnetite chemical syntheses in dry medium, which could also be used as an alternative for freshmen chemistry experiments. The proposed reaction was carried out in a muffle furnace by heating (i) a sol-gel preparation and (ii) natural hematite, under nitrogen atmosphere at 400 o C. The synthesized magnetite was characterized with powder X-ray diffraction and Mössbauer spectroscopy. Results show that magnetite samples have chemical properties as well as crystalline structure quite similar to those of standard natural magnetite.

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Magnesioferrita e caminho pedogenético de transformação de óxidos de ferro magnéticos em dois perfis de solo derivados de tufito da região do Alto Paranaíba (MG)

Abstract: RESUMO

Cited by 4 publications

References 21 publications

Magnetic Properties of Iron Sand from the Tor River Estuary, Sarmi, Papua

Magnetic Properties of Iron Sand from the Tor River Estuary, Sarmi, Papua

Pedogenic Iron Oxides in Iron-Rich Oxisols Developed from Mafic Rocks

Uma estratégia adaptada para síntese de magnetita

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