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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy (S) - IASPEI - International Association of Seismology and Physics of the Earth's Interior JSS001 Poster presentation 1725 Feature of the analysesof heterogeneous ores Dr. Artush Tamrazyan IUGG , IASPEI JSS IASPEI At X-ray radiometric approbation (XRA) of ores in conditions in situ or at their processing and enrichment, object of research are not homogeneous, heterogeneous environments. To present time a plenty of the works, the influences of heterogeneous effect devoted to studying on results XRA is known. However, all questions of the theory of heterogeneous effect, especially ways of his(its) account yet are not solved. We receive analytical formulas for calculation of streams of secondary radiations from heterogeneous environments with the various sizes and distributions of heterogeneouses. Taking into account, that distribution of ore grains in the heterogeneous environment has probability character for reception of a full picture cases their discrete binomial and continuous (normal) distributions are considered. With the purpose of finding - out of character of influence of large sizes particles and the law of their distribution to size of a stream of secondary radiations, the settlement data are compared to results of experimental researches. For experiment with fractionated chalcopyrite and syenite some groups of test in which contents of ore grains varied both the sizes, and were made. From comparison settlement and experimental data it is visible, that at the big sizes of particles calculations on binomial distribution are better coordinated with experiment, and with the small sizes the good consent with experiment is observed for normal distribution. The received data allow to conclude, that in the initial stage of processing and enrichment of ores distribution of ore inclusions in the environment submits binomial law, and in the following stages of processing when the sizes of particles and therefore, the quantity of grains in individual volume their distribution is close to the normal law is increased decrease. Knowing character of change of the law of distribution of ore grains in ore in different stages of itsdevelopment, the appropriate ways of realization X-ray radiometric method, taking into account influence of effect of heterogeneity easily get out. Keywords: x ray radiometric
IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy (S) - IASPEI - International Association of Seismology and Physics of the Earth's Interior JSS001 Poster presentation 1726 Natural magnetite nanoparticles from an iron-ore deposit: grain size effects in magnetic properties Dr. Luis M. Alva-Valdivia Paloemagnetism Universidad Nacional Autonoma de Mexico IAGA We report natural magnetite nanoparticles, 0.514 nm, from the mineralized zones of Pea Colorada ironore deposit. Crystallographic identification of magnetite nanostructures was done using high resolution transmission electron microscopy. Micrometric scale magnetite was magnetically reduced and divided into distinct range fractions: 8556 m, 5630 m, 3022 m, 2215 m, 1510 m, 107 m, and 7-2 m. Reduced magnetite was characterized by X-ray diffraction, high resolution transmission electron microscopy and high angle annular dark field. Magnetic properties show drastic changes when grain size exceeds the frontier from micro to nanometric sizes. The magnetic susceptibility obtained from frequency percent (fd%), report high values (13%) for the 214 nm fractions, attributed to dominant fractions of superparamagnetic particles, confirming the Mssbauer spectroscopy results. fd% < 5% variations in fractions from 567 m occur due to the presence of stable single domain grains. Nanometric and 0.2 to 7 m grain size magnetite particles require a magnetic field up to 152 mT to reach saturation during the isothermal remanent magnetization experiment. Coercivity of magnetite increase when the grain size decreases probably due to coupling effects. The magnetic susceptibility vs. temperature curves show that reversibility is due to magnetite nanoparticles. Keywords: magnetite nanoparticles, grain size, magnetic properties
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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy<br />
(S) - <strong>IASPEI</strong> - International Association of Seismology and Physics of the Earth's<br />
Interior<br />
JSS001 Poster presentation 1726<br />
Natural magnetite nanoparticles from an iron-ore deposit: grain size<br />
effects in magnetic properties<br />
Dr. Luis M. Alva-Valdivia<br />
Paloemagnetism Universidad Nacional Autonoma de Mexico IAGA<br />
We report natural magnetite nanoparticles, 0.514 nm, from the mineralized zones of Pea Colorada ironore<br />
deposit. Crystallographic identification of magnetite nanostructures was done using high resolution<br />
transmission electron microscopy. Micrometric scale magnetite was magnetically reduced and divided<br />
into distinct range fractions: 8556 m, 5630 m, 3022 m, 2215 m, 1510 m, 107 m, and 7-2 m. Reduced<br />
magnetite was characterized by X-ray diffraction, high resolution transmission electron microscopy and<br />
high angle annular dark field. Magnetic properties show drastic changes when grain size exceeds the<br />
frontier from micro to nanometric sizes. The magnetic susceptibility obtained from frequency percent<br />
(fd%), report high values (13%) for the 214 nm fractions, attributed to dominant fractions of<br />
superparamagnetic particles, confirming the Mssbauer spectroscopy results. fd% < 5% variations in<br />
fractions from 567 m occur due to the presence of stable single domain grains. Nanometric and 0.2 to 7<br />
m grain size magnetite particles require a magnetic field up to 152 mT to reach saturation during the<br />
isothermal remanent magnetization experiment. Coercivity of magnetite increase when the grain size<br />
decreases probably due to coupling effects. The magnetic susceptibility vs. temperature curves show<br />
that reversibility is due to magnetite nanoparticles.<br />
Keywords: magnetite nanoparticles, grain size, magnetic properties
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