The magnetic properties of certain soils indicate the widespread presence of ultrafine-grained magnetite, even where there is no detrital input of magnetite 1-3 . This suggests that in situformation of magnetite can occur under soil-forming conditions. Schwertmann and Taylor 4 have stated, however, that magnetite has not been found as a newly formed mineral in soils.

The production of ultrafine-grained magnetite by magnetotactic bacteria in surficial aerobic sediments may contribute significantly to the natural remanent magnetism of sediments 2-4. However, recent studies on iron reduction in anaerobic sediments suggested that bacteria can also generate magnetite in the absence of oxygen 5.

Ultrafine magnetite particles of 4-10 nm were prepared in aqueous solutions of polyvinylalcohol (PVA) or PVA with partially exchanged carboxyl groups. The mode of agglomeration and dispersion of the particles were different depending on the properties of polymers in the solvent.

This paper proposes a straightforward air-aqueous oxidation of St3 steel wastes for mass production of pure ultrafine magnetite. The characterization of the obtained product has been made by X-ray fluorescence analysis, X-ray diffraction, impedance spectroscopy, low-temperature nitrogen absorption method, Möss spectroscopy and optical microscopy.

Four samples containing ultrafine- and fine-grained magnetite of magnetoferritins and magnetotactic bacteria cells were magnetically characterized at both room and low temperatures. Transmission electron microscopy analysis showed that the biometrically synthesized magnetoferritins (M-HFn) have magnetite cores with a mean size of 5.3 ± 1.2 nm inside protein shells, while …

A facile and green route is presented for mass production of oriented magnetite porous fibers (with >96% in yield), based on the protein assisted hydrothermal method in citric aqueous solution. The magnetite fibers are nearly cylindrical in shape, several ten micrometres in length and 120 nm in mean diameter. The whole single fibers are packed by the ultrafine Fe 3 O 4 nanoparticles with ...

Ultrafine Magnetite Nanopowder: Synthesis, Characterization, and Preliminary Use as Filler of Polymethylmethacrylate Nanocomposites. Pietro Russo, 1 Domenico Acierno, 2 Mariano Palomba, 3 Gianfranco Carotenuto, 3 Roberto Rosa, 4 Antonino Rizzuti, 5 and Cristina Leonelli 4.

Two grades of magnetite were used for this series of tests. Type-I was an ultrafine magnetite with a top size of 15 µm, which was supplied by the Pea Ridge Iron Ore Company. Type-II was coarser (43% < 15µm) and was prepared by dry screening …

Ultrafine magnetite particles were prepared through a hydrothermal process at 130°–150°C from a solution of iron chloride and iron powder in the presence of urea. XRD and chemical analysis indicated that the product was magnetite. The size and morphology of the particles were studied by TEM.

Abstract In this communication, environmental friendly and biocompatible ultrafine super-paramagnetic magnetite nanoparticles (USPMNs) ferro-fluid was prepared by modifying co-precipitation green itinerary under optimized conditions. Phase pattern of USPMNs was confirmed by X-ray diffraction (XRD). Particle size of USPMNs was also estimated using the Scherrer's formula which turned out to …

Magnetite (Fe 3 O 4) is a mineral of great commercial value in that it is useful, e.g., in magnetic recording devices and as toner for plain paper copiers. Particularly desirable for these purposes is magnetite in ultrafine-grained (roughly 20-50 nanometers in diameter) form.

Request PDF | Micromagnetics and magnetomineralogy of Ultrafine magnetite inclusions in the Modipe Gabbro | Iron oxide inclusions in pyroxene crystals from the Modipe Gabbro, Botswana, have been ...

A new extraction technique now permits ultrafine magnetite crystals to be separated from a variety of deep-sea sediments. Morphologic characterization of these particles with transmission electron microscopy reveals the presence of several distinct crystal types, some of which closely resemble those formed by the magnetotactic bacteria. The apparently biogenic magnetite particles are of single ...

Request PDF | Solvent Extraction of Arsenic(V) with Dispersed Ultrafine Magnetite Particles. | The solvent extraction of arsenic(V) was investigated using heptane containing ultrafine magnetite ...

Pure ultrafine magnetite from carbon steel wastes // Materials Today: Proceedings: 3rd ISE Satellite Student Regional Symposium on Electrochemistry in Ukraine – Promising Materials and Processes in Applied Electrochemistry-2018, 18th April, 2018, Ukraine (special issue) / Edited by V. Barsukov, V. Khomenko, O. Linyucheva, Yu. Borysenko.

containing ultrafine magnetite and oleic acid, and a buffered aqueous solution of arsenic(V). When heptane containing 0.58 g/dm3 magnetite and 3.4 ×10–3 M of oleic acid was shaken with a buffered aqueous solution at pH 6, phase separation was insufficient. Oleic acid was thought to be responsible for the poor phase separation.

ultrafine magnetite powders in the light of the present results. The conversion experiments make it probable that a partially oxidized ultrafine magnetite powder is actually a mixture of fully oxidized (y-Fe,03) particles together with stoichiometric Fe304 particles. The alternative possibility that the particles are a uniformly ...

TEM observation revealed aggregates of small crystals of ultrafine magnetite which ranged in size from about 2 to 4 nanometers. Magnetic property by SQUID analysis showed the magnetite nanoparticles demonstrate superparamagnetic behavior. As a result, the method of the present study can be used to produce magnetite efficiently using inexpensive ...

Magnetite ultrafine particles/porous reduced graphene oxide in situ grown onto Ni as a binder-free electrode for supercapacitors Y. Mao, B. Zhou and S. Peng, RSC Adv., 2020, 10, 20753 DOI: 10.1039/D0RA03724A

@article{osti_110014, title = {The use of flotation to separate fine coal and ultrafine magnetite from dense-medium cyclone products}, author = {Polat, M and Klima, M S and Chander, S and Ahuja, G}, abstractNote = {A study was conducted to investigate the use of flotation in combination with dense-medium cycloning utilizing ultrafine ({minus}10 {micro}m) magnetite, as an integrated …

The distinct difference in the oxidative potential of maghemite and magnetite may be related to the oxidative state of the iron ions in the complex. In maghemite (Fe 2 O 3) iron ions are mostly Fe 3+, while in magnetite (Fe 3 O 4) they are a mixture of Fe 3+ and Fe 2+ with a Fe 2+ /Fe 3+ ratio of 0.435 (Table (Table1). 1).

Ultrafine . The percentage minus 45 microns for each grade is shown on the graph. MAGNETITE RHEOLOGY . For a given medium density, magnetite rheology is defined by both settling rate and viscosity. Settling Rate . A medium of the required density is made up by adding magnetite and water in the required ratio.

Ultrafine magnetite was prepared in aqueous solution by reflux method with ethylenediamine as precipitant. On partial substitution of ethylenediamine for distilled water in the solution, the crystallite was reduced in size linearly. Ethylenediamine worked as not only a …

Ultrafine magnetite particles are prepared through an electrochemical process, at room temperature, from an iron-based electrode immersed in an alkaline aqueous medium containing complexing compounds. XRD and chemical analysis indicate that the product is pure magnetite, Fe 3 O 4 . The size and morphology of the particles are studied by SEM.

Ultrafine palladium nanoparticles confined in core–shell magnetic porous organic polymer nanospheres as highly efficient hydrogenation catalyst Journal of Colloid and Interface Science ( IF 8.128) Pub Date :, DOI: 10.1016/j.jcis.2019.07.006

Depending on culture conditions and bacterial forms (Vali et al., 2004), the respiration of iron-reducing bacteria based on solid Fe(III) mineral phases produces extracellular magnetite crystals (Lovley et al., 1987; Lovley, 1991; Coker et al., 2008) of ultrafine grains with …

Ferromagnetic properties of ultrafine magnetite (Fe 3 O 4 ) particles were examined by the ESR and the static magnetic susceptibility measurements. Ferromagnetic resonance became to be observed at the particle size larger than 3.4 nm. This finding suggests that the bulk-like ferromagnetic state cannot be formed in the particle less than 3.4 nm diameter for magnetite.

For improving the strength of pellets made of ultrafine and super-high-grade magnetite concentrates, the influence of basicity (CaO/SiO 2 ratio) on the roasting and consolidation of pellets was investigated. The results showed that with the basicity of pellets increasing from 0.09 to 0.60, the compressive strength of both preheated and roasted pellets achieved an evident improvement from …

Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe 3 O 4.It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. It is the most magnetic of all the naturally occurring minerals on Earth. Naturally magnetized pieces of magnetite, called lodestone, will attract small pieces of ...

N2 - Effect of ultrafine powder of Hematite and Magnetite on granulation characteristics of iron oxide was investigated by mixing and exterior coating granulation. The results obtained are follows: (1) In the case of Hematite Ore H, particle diameter of granule is increase with increasing the amount of fine powder in both mixing granulation and ...