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1
Yanmin, Wang. "Wet magnetic concentration for weakly magnetic mineral fines and ultrafines." Doctoral thesis, Luleå, 1993. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26710.
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The first objective of the thesis was to reveal the characteristic magnetic behaviour of natural weakly magnetic minerals (such as hematite and chromite), and the size limits of the particles recoverable by the existing modem high intensity and high gradient magnetic separators. The second objective was to enhance the particle aggregation andlor the magnetic response for wet magnetic concentration of the ultrafines which escaped from the separators. It was observed that weakly magnetic natural minerals (hematite and chromite) exhibited variations in the magnetic behaviour with respect to magnetizing field, temperature and even particle size, It was indicated that high gradient magnetic separation with industrial matrices was efficient for weakly magnetic minerals as small as 10 um, but below this size, poor separation efficiency was obtained. In this thesis, modifications to the existing magnetic technology or alternative methods were investigated for the efficient recovery of particles below 10 gm. The technology or methods included "carrier" or "piggy-back" method, aggregation with magnetic bonding (with permanent or fieldinduced magnetic moment), and hydrophobic magnetite seeding. The thesis discusses the theoretical aspects of the problem and the experimental work. It was clearly demonstrated that wet magnetic concentration was more efficient for the ultrafine fractions whereas other methods could be used to increase the effective particle size dimensions andlor the magnetic susceptibilities.Godkänd; 1993; 20070426 (ysko)
2
Schmidt, Volkmar. "Magnetic and mineral fabrics in carbonate rocks /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17090.
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Smith, J. P. "Mineral magnetic studies on two Shropshire-Cheshire meres." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372707.
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Watson, D. J. "Mineral magnetic and palaeomagnetic properties of continental shelf sediments." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/14648.
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Yang, Ying Ping. "Electromagnetic characteristics of synthetic rocks, and sulphide and oxide mineral assemblages." Thesis, The University of Sydney, 1995. https://hdl.handle.net/2123/26849.
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An understanding of the electromagnetic characteristics of sulphide-bearing and magnetite-bearing rock and ore samples is important in the interpretation of electromagnetic (EM) exploration data. In this research study of electromagnetic conductivity characteristics, a theoretical measurement basis was developed, synthetic analogue materials were studied and the theory and analogue results were related to rock samples of varied mineralogy, texture and mineral concentration.
The theory developed for cylindrical core sample EM measurements agreed with experiments performed on standard conductive samples using a multi-frequency coilbridge system in the 10 kHz to 4 MHz range. Skin effect was an important limitation to EM measurements on conductive (o > 1000 S/m) core samples but can be effectively monitored by spectral measurements.
Measurements on 104 synthetic cores, of five types, revealed the relationship between apparent EM conductivity and the structure and arrangement of the conducting materials. These analogue cores contained a range of conductors, including copper wires, graphite powder, aluminium particles and magnetite/ilmenite grains, set in a matrix of insulating plaster or wax, representing models of layered, stringer, disseminated, network, massive and magnetite-rich mineralisation. A mechanism attributed to magnetic loss produced unrealistically high EM apparent conductivities for magnetite—bearing samples, especially at low frequencies (f < 100 kHz). For a conductive magnetite sample (6 > 1 S/m), the effect of magnetic loss can be eliminated at high frequencies (f > 400 kHz) and the ohmic conductivity of the magnetite sample can then be estimated.
A total of 254 sulphide—bearing and magnetite-rich samples from 15 different geological environments constituted the natural materials used in this research. The sulphides, including chalcopyrite, pyrite, galena, sphalerite and pyrrhotite, and magnetite occurred in varying proportions and diverse fabrics in these samples. Complementary measurements of galvanic conductivity, density and magnetic susceptibility and thin section mineralogy results provided essential auxiliary information for the analysis of the EM data. The electrical conductivity of a rock is controlled by its mineralogy, mineral habit, mode of connectivity of conducting minerals and rock fabric. Texture may have an overwhelming effect on the EM and galvanic conductivities of rock samples. The conductivities of the massive sulphides studied ranged from thousands of S/m to a few tens of thousands of S/m for pyrrhotite, hundreds of S/m to thousands of S/m for chalcopyrite and galena, and a few S/m to hundreds of S/m for pyrite. Sulphide-free magnetite-bearing rocks generally are, at best, only moderate conductors (l S/m to 10 S/m) and then only with a large proportion of magnetite. Coarse grainsize in massive magnetite significantly enhances conductivity (up to hundreds of S/m). There is a clear contrast in the conductivity behaviour of networks and discrete aggregations of conducting minerals. When pyrrhotite is present, it usually dominates the conductivity response. Chalcopyrite also makes an effective contribution, whereas pyrite and magnetite often do not.
Conductivity modelling of concentration variations can be achieved using appropriate
empirical relations for different cases. For dispersed conducting euhedral cubic minerals such as pyrite or magnetite, Maxwell's mixing law can be applied. When a conducting material, such as pyrite or magnetite, changes from a dispersed phase to conductive channels with increasing concentration, percolation theory can be applied The observed critical concentrations, where the conducting minerals start to change from dispersed phases to continuous phases electrically, are 20 percent to 50 percent for pyrite, 40 percent to 80 percent for magnetite. For pyrrhotite or Chalcopyrite, present as continuous conducting minerals, it appears that a power law can be applied and the power exponent may vary between 1.5 and 5.5, depending on the conducting network structure.
For a laboratory core sample with dispersed conducting particles, the calculated and
observed diminution of measured EM conductivity with an increase in diameter of the
sample suggests that EM exploration methods may not work well in conductivity
prospecting for a disseminated target. For a heterogeneous mineralised rock sample,
applications of laboratory—determined EM conductivity to field situations generally need to take account of the structure or texture of the conducting minerals.
The research results of this thesis are intended as a contribution to the understanding of laboratory electromagnetic conductivity measurements. The results have important applications to the designs and evaluations of field-based EM systems in the exploration for metallic lustre sulphide and oxide economic mineral deposits in a variety of geological settings.
6
Sandström, Dan. "Solid state nuclear magnetic resonance studies of synthetic mineral surfaces." Doctoral thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26480.
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Solid state 1H, 31P and 27Al Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) was used in studies of surface species formed on a synthetic fluorapatite in aqueous suspensions at different pH with or without ions or ion complexes of iron or aluminium in the suspension. Different sites related to the PO43- ions at the mineral surface were suggested, POx, POxH and POxH2. Also, three sites formed of Ca2+, H+ and OH- ions at the fluorapatite surface CaOH2+, CaOH and Ca(OH) 2- were suggested. Both single-pulse and cross polarization MAS NMR experiments were used to measure the 1H, 31P and 27Al isotropic chemical shifts. In the 1H to 31P cross polarization experiments the contact time was varied in order to differentiate the resonance liners corresponding to different surface sites from the resonance lines assigned to the PO43- ions in the crystal structure of fluorapatite. In the solid state dipole-dipole recoupling MAS NMR experiments the sequence XY8-DRAMA was used in studies of distances between O,O'- dialkyldithiophosphates adsorbed on synthetic galena (PbS). The sequence was tested experimentally and gave highest double-quantum excitation efficiency of the tested dipole-dipole recoupling sequences tested at the spinning frequency 4.2 kHz. A new sequence IRS-DRAMA was derived analytically and showed high double quantum excitation efficiency in a broad interval of the 31P resonance frequencies at the spinning frequency 2.1 kHz.Godkänd; 2006; 20061205 (haneit)
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Sandström, Dan. "Solid state nuclear magnetic resonance studies of synthetic mineral surfaces /." Luleå : Luleå tekniska universitet/Tillämpad kemi och geovetenskap/Kemi, 2006. http://epubl.ltu.se/1402-1544/2006/26/LTU-DT-0626-SE.pdf.
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Hannam, Jacqueline Ann. "Processes and timescales of secondary magnetic mineral formation in topsoils." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366393.
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Yu, L. "Environmental applications of mineral magnetic measurement : Towards a quantitative approach." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234577.
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Jirestig, Jan A. "High intensity and high gradient magnetic separation in mineral processing." Doctoral thesis, Luleå tekniska universitet, 1994. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25815.
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Natural minerals often lack well defined magnetic susceptibilities. Instead they must be thought of as occurring in a susceptibility range where the bulk susceptibility is affected by present impurities. Inclusions or foreign atoms in solid solution may alter a materials magnetic properties to a large extent. Mixed particles of dia andlor paramagnetic materials display a linear relationship while ferromagnetic inclusions involve a demagnetisation factor. The susceptibility distribution of value minerals in relation to gangue in the ore is the most important factor governing magnetic separation performance. Until recently, high gradient and high intensity separators of matrix type were exclusively used in wet processing. Now, new dry separators are extending the particle range for dry, fine particle separation. The capture characteristics of the matrix has been shown to change with the magnetic field strength. The separation cut is more precise at high fields, at low fields the capture probability graph cants. By superimposing the capture function on the susceptibility distribution of an ore, it is shown that materials containing value minerals at either high or low susceptibility is ideal for HGMS separation. Complex ores carrying value and gangue minerals distributed over a wide susceptibility range are unfavourable. The former situation is common in industrial mineral processing and in the upgrading of flotation concentrates. The latter susceptibility distribution is very common in complex sulphide ore feeds.Godkänd; 1994; 20070429 (ysko)
11
Jones, M. D. H. "The magnetic deposition record in some Scandinavian peat profiles." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377116.
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This study uses a range of magnetic parameters, eg. Susceptibility (X), Saturation Isothermal Remanence (SIRM), Anhysteretic Remanence (ARM), interparametric ratios (ARM/X, SIRM/X, SIRM/ARM) and coercivity of remanence data (IRM-n/SIRM, (BO)CR), coupled with various dating methods (eg. moss increment counting and radiometric dating) to estimate the magnetic deposition onto some Scandinavian peat bogs. The sites available included 4 from southern Finland, 5 from northern Finland, 2 from northern Norway and 1 from southern Denmark. In addition to the magnetic techniques, a range of chemical determinations (iron, copper, zinc, lead, nickel and, where available, manganese) have been made, or are utilised, for all the peat cores. The reproducibility of the primary magnetic deposition record at Kaurastensuo, southern Finland has been examined. The rise in magnetic particulate concentrations, termed the magnetic 'take-off', was consistently dated to about 1931 for 7 of the 8 cores used, regardless of hummock-hollow micro topography. The persistence of magnetic minerals over timescales of 101-103 years has been examined by means of long core profiles from 4 southern Finnish bogs. The mineral magnetic and heavy metal profiles (iron, copper, zinc, lead and nickel) were in reasonable accord with the development of the individual bogs above different mineral soils. The development of peat profiles is dated from between 8000-9000 years BP using 14C dates spanning both the ombrotrophic and minerotrophic phases. The availability of moss increment counts for the northern Scandinavian sites and 210Pb determinations for Draved Moss, southern Denmark and Mo-I-Rana, northern Norway, has allowed estimates of variation in the magnetic deposition to be made. The northern Scandinavian sites all show increasing deposition from 1900, although maximum surface deposition varies from site to site, between 1.24-22.6 10-6Am2yr-1. The magnetic deposition at Draved Moss was estimated to be 21.6 10-6Am2yr-1 at a subsurface maximum dated to between 1967-1978. The increase in lead deposition at Draved Moss is in reasonable agreement with that of published lead deposition profiles from the same site, using earlier attempts at 210Pb determinations. At Mo-I-Rana, northern Norway the maximum magnetic deposition value is estimated to be 8.65 10-6Am'yr-1 for the surface slice, spanning the last 21 years. Any spatial variation in deposition within the Scandinavian sites appears to be partly masked by site-specific features, for example the close proximity of industrial sources at 2 of the Finnish sites and the iron and steel works at Mo-I-Rana. Magnetic deposition at the latter site is in good agreement with the history of iron and steel production within the region since the turn of the century.
12
Hall, Stephen Thomas. "Enhancement of magnetic susceptibility by leaching and application in mineral separation." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=71807.
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Enhancement of the magnetic susceptibility of pyrite particles is observed following a mild oxidative pressure leach. This increase is studied for a range of experimental conditions. The increase in susceptibility is attributed to the formation of a thin layer of ferromagnetic oxides. This layer of leach reaction products has been extensively studied using various analytical techniques. The species identified are (gamma)-Fe(,2)O(,3) and Fe(,3)O(,4), which supports a previously postulated reaction model.This leach treatment significantly increases the magnetic susceptibility of coal-pyrite permitting improved high-gradient magnetic desulfurization of a high pyritic sulfur coal.
The leach treatment also enhances the magnetic susceptibility of other iron-containing mineral sulfides. However, application of this leach pretreatment in sulfide/sulfide separations is limited due to galvanic coupling effects which passivate the susceptibility increase reaction. In the presence of oxides, coal and probably other non-sulfides passivation does not occur and the susceptibility of the iron-bearing sulfide increases. The potential exists for the application of the leach as a pretreatment in enhancing fine iron-containing sulfide/non-sulfide magnetic separations.
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Walden, John. "The use of mineral magnetic analysis in the study of glacial diamicts." Thesis, University of Wolverhampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259185.
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France, Derek Edward. "The mineral magnetic characterisation of goethite and haematite in soils and sediments." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263900.
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Kerbey, Mark Henry. "Tag deposition kinetics and selectivity in the magnetic tagging of mineral suspensions." Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312285.
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Jones, Hannah Amy. "Sediments in urbanised river catchments : an integrated sedimentological and magnetic mineral approach." Thesis, Manchester Metropolitan University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412634.
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Ivakhnenko, Oleksandr Petrovych. "Magnetic analysis of petroleum reservoir fluids, matrix mineral assemblages and fluid-rock interactions." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/140.
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Fischer, Håkon. "Magnetic and spectroscopic investigations of mineral transformations in mixed-valence oxides and magnesium silicates /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17774.
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Sandström, Dan. "Dipolar recoupling sequences in ¹³C and ³¹P nuclear magnetic resonance studies of mineral surfaces /." Luleå, 2004. http://epubl.luth.se/1402-1757/2004/022.
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Crosby, Christopher James. "Application of mineral magnetic measurements as a pollution proxy for urban road deposited sediment." Thesis, University of Wolverhampton, 2012. http://hdl.handle.net/2436/265493.
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Road Deposited Sediment (RDS) is an important pathway of pollution material in the urban environment. Traditional particulate matter (PM) monitoring methods are typically expensive and time consuming. To date, urban sediment studies have not fully explored the application of mineral magnetic technologies as an alternative to characterise RDS or, perhaps more importantly, their use as particle size proxy. Therefore, this study addresses these issues by determining the extent of any linkages between magnetic properties and the physio-chemical concentrations of RDS. Investigations have focussed on a spatial temporal study (2008-10) of RDS from the City of Wolverhampton (n = 546) and a similar ‘snap-shot’ study of eight selected town and cities across the UK (n = 306), plus a comparison investigation linked to regional monitoring of air sampling units (ASU) (n = 208). A suite of analytical approaches, namely mineral magnetism, laser diffraction, X-Ray Fluorescence spectroscopy (XRF), Scanning Electron Microscopy (SEM) and Loss on Ignition (LOI), were employed to characterize sample properties. Data interrogation identified mainly weak correlations exist between most mineral magnetic parameters and particle size classes (i.e. sand, silt and clay) and respiratory health-related size classes (i.e. PM10, PM2.5 and PM1.0). The few strongest correlations (p <0.001) were found between mineral magnetic concentration and
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Booth, Colin Anthony. "Sediment-source-linkages in the Gwendraeth Estuary, south Wales, based on mineral magnetic analyses." Thesis, University of Wolverhampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394037.
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Jones, Keith Richard. "Circulation, deposition and post-depositional changes of sediment in two Welsh estuaries : a mineral magnetic investigation." Thesis, University of Wolverhampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366147.
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Davies, Erika. "Finding a place for citrate : an NMR crystallographic approach to the study of bone mineral." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610808.
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Gungor, Kazim. "Production Of Heavy-media-quality Magnetite Concentrate From Kesikkopru Iron Ore Tailings." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611830/index.pdf.
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ABSTRACT
PRODUCTION OF HEAVY-MEDIA-QUALITY MAGNETITE CONCENTRATE FROM KESiKKÖPRÜ
IRON ORE TAILINGS Gü
ngö
r, Kazim M. Sc. Department of Mining Engineering Supervisor: Prof. Dr. M. Ü
mit Atalay May 2010, 91 pages The aim of this research was to investigate the possibility of the production of a magnetite concentrate which is suitable for preparation of heavy media from iron ore tailings of Gü
ncem Mining Company magnetic separation facility. During the study, three different tailings named as low grade, medium grade and high grade with 5.91 % Fe3O4, 19.06 % Fe3O4 and 37.06 % Fe3O4, respectively, were used. Mineralogical analyses of test samples showed that magnetite and hematite were the major ore minerals while pyrite and chalcopyrite were found in trace amounts. Actimolite, tremolite, epidote, chlorite, quartz, calcite, and dolomite were the gangue minerals. The effects of feed particle size and applied magnetic field intensity on the Fe3O4 grade and recovery of concentrate were examined throughout magnetic concentration tests. The highest grade magnetite concentrate with 79.98% Fe3O4 content was obtained with 65.42% recovery from 100% -75 micron size feed at 1000 Gauss magnetic field intensity from high grade tailing.
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Kyle, Clinton. "Influence of magnetic field exposure and clay mineral addition on the fractionation of Greek yogurt whey components." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19021.
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Master of ScienceFood Science Institute
Jayendra Amamcharla
Greek yogurt is one of the largest-growing sectors in the dairy industry accounting for over 25% of yogurt sales in the United States. Greek yogurt is produced by removing a portion of water and water soluble components from yogurt. Consequently, a large quantity of Greek yogurt whey (GYW) is being produced as a co-product. GYW is compositionally different from cheese whey, and thus poses economic and environmental challenges to the dairy industry. The objective of the present study was to evaluate two physical treatments as alternative methods for separating valuable GYW components: magnetic fluid treatment (MFT) and the addition of sepiolite, a clay mineral. A MFT chamber was designed using four pairs of neodymium magnets arranged to produce a magnetic field strength of 0.6 Tesla. Three batches of GYW each from two manufacturers were procured. A 2×3 factorial design was used with MFT or without MFT and the addition of zero, two, or four grams of sepiolite per 100g of GYW. The pH of GYW was adjusted to 7.2 using 5N NaOH solution, and the GYW was pumped at a rate of 7.5 L/min through the MFT system with or without MFT chamber attached. The sample was split into three sub-samples, heated to 80°C, and sepiolite was added as per the experimental design. The samples were centrifuged at 1,000g for five minutes. The top aqueous layer was separated and analyzed for total solids, ash, lactose, protein, calcium, phosphates, and sodium content along with color. MFT did not influence the analyzed whey components (P > 0.05) except for lactose. However, addition of sepiolite influenced protein content and a* and b* color values for the top aqueous layers (P < 0.05). Both levels of sepiolite addition resulted in about a 50% decrease in protein compared to original GYW. Adding two grams of Sepiolite per 100g of GYW from manufacturer 1 resulted in b* decreasing from 25.99 to 8.16 compared to treated GYW with no sepiolite. Sepiolite was found to have possible applications in the removal of proteins and color pigments in GYW.
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Belo, Fernandes Ivan. "Geometallurgical approach to understand how the variability in mineralogy at Zinkgruvan orebodies affects the need for copper activation in the bulk rougher-scavenger flotation." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65392.
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Zinkgruvan is a Pb-Zn-Ag deposit located in south-central Sweden, owned and operated by Lundin Mining. The ore is beneficiated by a collective-selective flotation circuit, recovering both galena and sphalerite in a bulk rougher-scavenger flotation stage and later on separating them into two final products. Opportunities for increase in zinc recovery in the bulk rougher scavenger flotation stage have been identified as the plant is relying on natural Pb-activation to process the ore. Process mineralogical tools were used to characterize four different orebodies from Zinkgruvan (Burkland, Borta Bakom, Nygruvan and Sävsjön) and evaluate the metallurgical performance for flotation and magnetic separation, following a geometallurgical approach to better understand and predict the behavior of such ore types in processing plant. The first hypothesis in this thesis is that by addition of copper sulfate and increased collector dosage, Zn recovery will be improved without being detrimental to galena flotation. Results demonstrated that there is a significant increase in Zn recovery by further increasing collector dosage and copper-activating the flotation pulp in the scavenger stage. For instance, an increase in zinc recovery up to 16% has been achieved after addition of copper sulfate. Galena is readily floatable while sphalerite takes longer to be recovered. In addition, iron sulfides take longer to be recovered and, after addition of copper sulfate, there was an increase in iron sulfide recovery. The amount of iron sulfides reporting to the concentrate should still not be a problem to the plant. Most of the Fe in the concentrate is still coming from the sphalerite lattice. However, it might be that some orebodies coming into production in the near future have higher amounts of pyrrhotite, which might be a problem. Therefore, magnetic separation methods have been tested to remove pyrrhotite from the bulk ore. The second hypothesis is that the high Fe content in the concentrate might be due to the presence of iron sulfides, in which case they could be selectively removed by magnetic separation. XRD analyses demonstrated that Sävsjön is a highly variable orebody, and that its high Fe content varies with the location inside the orebody, being caused by either iron sulfide or iron oxide minerals. Both monoclinic and hexagonal pyrrhotite have been observed. Davis Tube could remove monoclinic pyrrhotite but it was very inefficient when dealing with hexagonal pyrrhotite. WHIMS, on the other hand, performed well for both types of pyrrhotite. When applying Davis Tube on Sävsjön OLD feed, a concentrate with up to 52.3% pyrrhotite is achieved, at a recovery of 35.32%. However, sphalerite is also reporting to the magnetic concentrate, which would generate Zn losses for the overall process. Zinc losses were up to 15.3% when the highest field strength was applied. Therefore, the applicability of magnetic separation for Zinkgruvan ore must be further evaluated.
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Al-Ali, Safaa Hussein Ali. "Mineralogy and mineral processing to optimise recovery of synchysite-(Ce) and apatite from carbonatite at Songwe Hill, Malawi." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/28823.
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Rare earth elements (REE) are considered as critical and non-substitutable metals for electronics and green technology. A greater diversity of supply is needed and the REE occur in a wide range of REE- and REE-bearing minerals within different ore deposit types. The beneficiation processes for REE ores can vary widely based on their mineralogy and texture. It is, therefore, essential to understand the mineralogical characteristics when designing processing routes. Little research was carried out on this topic until the last few years, apart from bastnäsite, monazite, and xenotime, and most REE minerals in deposits currently under exploration are poorly understood in terms of processing characteristics. This geometallurgical study brings together the results of process mineralogy and minerals processing to recover synchysite-(Ce) and apatite from the carbonatite at Songwe Hill, Malawi. This deposit is unusual because it is a potential carbonatite source of both LREE and HREE. Results from previous flowsheet development studies on this deposit suggest that flotation is the most promising processing route and therefore this study concentrated on testing this hypothesis. It sought to understand the mineralogy better in order to predict processing response and carried out a series of flotation experiments to improve the processing efficiency. It also investigated the fundamental magnetic properties of the rare earth fluorcarbonate minerals (including synchysite) and established for the first time that there is a systematic variation in their properties that can be applied to minerals processing. Eight samples of REE carbonatite drill core, crushed to 1700 μm, and a composite sample ground to 53 μm and 38 μm were used throughout this research. Automated mineralogy (QEMSCAN®) was applied to determine the mineralogical characteristics of the ore deposit. This utilised a novel species identification protocol (SIP) for REE minerals in carbonatites, which was validated by electron microscopy (SEM-EDS), and electron probe microanalysis (EPMA). The principal REE minerals at Songwe are the REE fluorcarbonates, synchysite-(Ce) and also parisite-(Ce). These are challenging minerals for automated mineralogical techniques owing to their chemical similarity and common occurrence either as bladed (needle-like) crystals, which is the main textural type at Songwe Hill, or as syntaxial intergrowths. However, using the SIP developed in this study, the QEMSCAN® can distinguish between these minerals based on the Ca content and can also recognise syntaxial intergrowths on a scale of about > 20 μm. The Songwe Hill carbonatite hosts about 6 wt% to 10 wt% of REE- and REE-bearing minerals. Apatite hosts the more valuable HREE in addition to P2O5, followed by synchysite-(Ce)/parisite-(Ce) (mainly synchysite-(Ce)), and minor florencite-(Ce), which host the LREE. These minerals are commonly associated with the predominant gangue minerals, ankerite and calcite, and, to a lesser extent Fe- Ox/CO3 and K-feldspar, strontianite and baryte. Fundamental magnetic properties of pure REE fluorcarbonate single crystal minerals using a vibrating sample magnetometer (VSM) were determined. The magnetic susceptibility is highly dependent on the mineral composition. It is positive (paramagnetic) for bastnäsite-(Ce) and gradually decreases as the amount of Ca increases in parisite-(Ce), becoming negative (diamagnetic) for the Ca-rich member of the series, röntgenite. Synchysite-(Ce) in this deposit was experimentally determined by magnetic separation and behaved as a diamagnetic mineral. This can be explained by the layered structure common to the REE fluorcarbonate series minerals. Selected laboratory scale mineral processing experiments including magnetic separation and froth flotation were performed. Pre-concentration tests by magnetic separation showed a recovery of 84% for P2O5, 80% for Y2O3, and 76% for Ce2O3 in the non-magnetic product, with gangue minerals rejection of about 49% for ankerite and 48% for Fe-Ox/CO3 to the magnetic product. Apatite and synchysite-(Ce) loss to the magnetic product is mainly the result of their association with the paramagnetic minerals i.e. ankerite and Fe-Ox/CO3 as indicated by automated mineralogy. A spectrophotometer was utilised to measure the solubility of the organic chemical reagents including fatty acids and lignin sulphonate in different alkaline solutions and to determine the appropriate operating parameters for bench flotation tests. The results indicated that the solubility of fatty acids increased with increasing the pH value from 8.5 to 10.5, while the opposite was observed for lignin sulphonate. 35 bench-scale froth flotation tests under a wide range of chemical and operating conditions including pH modifiers and dosages, soluble and insoluble collectors, depressants, temperature, and conditioning time were performed. The results demonstrated that fatty acids and lignin sulphonate are sensitive to changes in pH, conditioning time, and temperature. These factors significantly affected flotation efficiency. A recovery of 86% for P2O5 and 74% for both of Y2O3 and Ce2O3 with TREO upgrading from 1.6 wt% to 3.8 wt% at a mass pull of 31% were achieved under a constant pulp pH of 9.5, elevated temperature, and long conditioning time. This study suggests that combining magnetic separation and froth flotation techniques to pre-concentrate and upgrade the REE- and REE-bearing minerals, should be considered further to minimise the cost of the chemical reagents used in froth flotation and gangue leaching.
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Batista, Sergio Luchini. "Osteoporose na doença de Cushing: valor preditivo da quantificação de adiposidade visceral e óssea sobre a remodelação e densidade mineral óssea." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/17/17138/tde-30032017-085813/.
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As propriedades anti-inflamatórias e imunossupressoras dos glicocorticoides (GC) justificam o uso destes esteroides em diversas condições clínicas, apesar dos seus importantes efeitos adversos. A osteoporose induzida por glicocorticoide (OIG) é considerada a causa mais importante de osteoporose secundária. Trata-se de uma doença multifatorial que envolve alterações sistêmicas, teciduais e da sinalização das células ósseas. Além disso, o hipercortisolismo também se associa à obesidade, redistribuição de gordura, resistência insulínica e diabetes mellitus. Curiosamente, nestes distúrbios metabólicos em que a massa óssea está preservada, há maior fragilidade óssea. Nos últimos anos, diversas evidências mostram complexa interação entre o metabolismo mineral e o energético, em particular entre o tecido adiposo e ósseo. Neste cenário, a doença de Cushing (DC) é um modelo clínico conveniente para avaliar diversos mecanismos envolvidos no complexo processo de desenvolvimento de osteoporose. O objetivo deste trabalho foi avaliar, em um estudo basal e em um estudo prospectivo, diversos aspectos da interação entre o metabolismo mineral e energético em mulheres com DC e o seu possível impacto sobre a massa óssea, bem como a associação entre a massa óssea e os diversos tipos de tecido adiposo. No estudo basal, avaliamos três grupos de indivíduos, pareados por sexo e idade: grupo controle (C; n=27), grupo obeso (O; n=16) e grupo doença de Cushing (DC; n=16). No estudo prospectivo, avaliamos o grupo DC em três momentos: pré-operatório (Pré-op; n=11), 6º mês pós-operatório (6º mês PO; n=10) e 12º mês pósoperatório (12º mês PO; n= 10). No estudo basal, os grupos O e DC diferiram em relação ao C quanto ao peso e IMC (p<0,05). O grupo DC apresentou valores significativamente maiores de glicemia, insulinemia, hemoglobina glicosilada (HbA1c), HOMA-IR e leptina em relação aos grupos C e O (p<0,05). Adicionalmente, o grupo DC mostrou níveis baixos de osteocalcina em relação aos grupos C e O (p<0,05) e também de PTH, 25-OH vitamina D (25(OH)D) e adiponectina em relação ao grupo C (p<0,05). Não houve diferença entre os grupos em relação às dosagens de IGF-I e preadipocyte factor 1 (Pref-1). O grupo DC apresentou menor massa óssea em coluna lombar em relação aos grupos C e O (p<0,05) e menor massa óssea em corpo total quando comparado ao grupo O (p<0,05). O Trabecular bone score (TBS) foi capaz de evidenciar prejuízo na qualidade óssea nos grupos O e DC, mostrando comprometimento maior no grupo DC (p<0,05). A adiposidade de medula óssea (AMO) de L3 foi significativamente maior no grupo DC em relação aos grupos C e O (p<0,05). O grupo DC apresentou maior teor de tecido adiposo subcutâneo (SAT), visceral (VAT), relação VAT/SAT e de lipídeos intra-hepáticos (IHL) em relação ao grupo C (p<0,05). Adicionalmente, o grupo DC apresentou maior teor de VAT em relação ao grupo O (p<0,05). A osteocalcina se correlacionou de maneira positiva com TBS (r=0,5, p<0,0001) e negativa com HOMA-IR (r=-0,4, p<0,01) e AMO de L3 (r=-0,4, p<0,01). O TBS apresentou correlação negativa com HOMA-IR (r=-0,6, p<0,0001) e AMO de L3 (r=-0,5, p<0,001). A AMO de L3 se correlacionou positivamente com IMC (r=0,4, p<0,01), HOMA-IR (r=0,3, p<0,05), leptina (r=0,3, p<0,05), relação VAT/SAT (r=0,6, p<0,0001) e IHL (r=0,5, p<0,05). No estudo prospectivo, houve redução do peso e IMC e dos níveis de glicemia, insulinemia, HOMA-IR, hemoglobina glicada e leptina (p<0,05). Adicionalmente, houve aumento dos níveis de 25(OH)D, osteocalcina e deoxipiridinolina (p<0,05). Não houve diferenças significativas entre os níveis de Pref-1 e adiponectina. O TBS manteve-se estável e não houve aparecimento de novas fraturas pelo vertebral fracture assessment (VFA). Na composição corporal por dual-energy X-ray absorptiometry (DXA), houve redução da massa gorda total e melhora no índice de massa magra apendicular pelo Foundation for the National Institutes of Health (FNIH) (p<0,05). A AMO de L3 reduziu significativamente no 6º mês PO, mantendo-se estável no 12º mês PO (p<0,05). Houve redução significativa do VAT, relação VAT/SAT e IHL no seguimento prospectivo (p<0,05). O presente estudo reafirma dados anteriores que mostram que o hipercortisolismo endógeno exerce profundo efeito negativo sobre o esqueleto, em particular sobre o osso trabecular. Além disto, é o primeiro estudo a mostrar que existe correlação negativa entre o TBS com HOMA-IR e AMO; é possível que as alterações do metabolismo energético sejam, pelo menos em parte, responsáveis pelo maior risco de fratura na DC.The anti-inflammatory and immunosuppressive properties of glucocorticoids (GC) justify the use of these steroids in various clinical conditions, despite its significant adverse effects. Osteoporosis induced by glucocorticoids (OIG) is considered the most important cause of secondary osteoporosis. It is a multifactorial disease involving systemic, tissue and bone cell signaling changes. Furthermore, hypercortisolism is also associated with obesity, redistribution of fat, insulin resistance and diabetes mellitus. Interestingly, these metabolic disorders in which bone mass is preserved, there is increased bone fragility. In recent years, evidence shows various complex interaction between the mineral and energy metabolism, in particular between adipose tissue and bone. In this scenario, Cushing\'s disease (CD) is a desirable clinical model to evaluate various mechanisms involved in the complex process of developing osteoporosis. The objective of this study was to evaluate, in a baseline study and a prospective study, various aspects of the interaction between the mineral and energy metabolism in women with DC and their possible impact on bone mass, as well as the association between bone mass and different types of adipose tissue. In the baseline study, we evaluated three groups of individuals, matched by sex and age: control group (C, n = 27), obese (O; n = 16) and Cushing\'s disease group (CD, n = 16). In the prospective study, we evaluated the CD group at three time points: preoperative (Pre-op; n = 11), 6 months postoperative (6th month PO; n = 10) and 12 months postoperatively (12th month PO; n = 10). In the baseline study, the O and CD groups differed in relation to C as the weight and BMI (p <0.05). The CD group showed significantly higher blood glucose, insulin, glycosylated hemoglobin (HbA1c), HOMA-IR and leptin in relation to the C and O groups (p <0.05). Additionally, the CD group showed lower levels of osteocalcin in relation to the C and O groups (p <0.05) as well as PTH, 25-OH vitamin D (25 (OH) D), and adiponectin in relation to the C group (P <0.05). There was no difference between the groups regarding dosages of IGF-I and preadipocyte factor 1 (Pref-1). The CD group had lower bone mass in the lumbar spine in relation to the C and O groups (p <0.05) and lower bone mass in the total body when compared to the O group (P <0.05). The Trabecular bone score (TBS) was able to show impaired bone quality in groups O and CD, showing greater involvement in CD group (p <0.05). Bone marrow adiposity (BMA) in L3 was significantly higher in the CD group compared to the C and O groups (p <0.05). The CD group showed increased subcutaneous fat content (SAT), visceral (VAT), VAT/SAT ratio and intrahepatic lipid (IHL) in relation to the C group (p<0.05). Additionally, the CD group had a higher content of VAT in relation to the O group (p<0.05). Osteocalcin correlated positively with TBS (r = 0.5, p <0.0001) and negatively with HOMA-IR (r = -0.4, p <0.01) and AMO of L3 (r = - 0.4, p <0.01). The TBS was negatively correlated with HOMA-IR index (r = -0.6, p <0.0001) and AMO of L3 (r = - 0.5, p <0.001). The AMO of L3 positively correlated with BMI (r = 0.4, p <0.01), HOMA-IR (r = 0.3, p <0.05), leptin (r = 0.3, p < 0.05), VAT/SAT ratio (r = 0.6, p <0.0001) and IHL (r = 0.5, p <0.05). In the prospective study, there was a reduction in weight and BMI and blood glucose, insulin, HOMA-IR, glycated hemoglobin and leptin (p <0.05). Additionally, there was increased levels of 25(OH)D, osteocalcin and deoxypyridinoline (p <0.05). There were no significant differences between the levels of adiponectin and Pref-1. The TBS was stable and there was no occurance of new fractures by vertebral fracture assessment (VFA). In body composition by dual-energy X-ray absorptiometry (DXA), threre was a reduction of total fat mass and improvement in apendicular lean body mass index by Foundation for the National Institutes of Health (FNIH) (p <0.05). The BMA of L3 significantly reduced in the 6th month PO, remaining stable on the 12th month PO (p <0.05). There was a significant reduction of VAT, VAT/SAT ratio and IHL in the prospective follow-up (p <0.05). This study confirms previous data showing that endogenous hypercortisolism has a profound negative effect on the skeleton, in particular on trabecular bone. Moreover, it is the first study to show that there is a negative correlation between TBS with HOMA-IR and BMA; it is possible that changes in energy metabolism are at least partly responsible for the increased risk of fracture in DC.
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Hutchinson, Simon Mark. "The use of mineral magnetic and radiometric measurements in the study of erosion processes and sediment sources in upland catchments." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277486.
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Dillon, Melanie [Verfasser], Ulrich [Akademischer Betreuer] Bleil, and Sabine [Akademischer Betreuer] Kasten. "Assessing the fidelity of the marine sedimentary magnetic record:Preservation and diagenetic alteration of magnetic mineral assemblages in upwelling regions off western Africa / Melanie Dillon. Gutachter: Ulrich Bleil ; Sabine Kasten. Betreuer: Ulrich Bleil." Bremen : Staats- und Universitätsbibliothek Bremen, 2008. http://d-nb.info/1072572273/34.
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Carvalho, Bruno César Lage de. "Aproveitamento de minérios de ferro de baixo teor: tendências, tecnologias utilizadas e influências no sequenciamento de lavra." Programa de Pós-Graduação em Engenharia Mineral. Departamento de Engenharia de Minas, Escola de Minas, Universidade Federal de Ouro Preto, 2012. http://www.repositorio.ufop.br/handle/123456789/2346.
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Essa dissertação descreve a situação atual e as tendências relacionadas ao tratamento de minérios de ferro de baixo teor na indústria mineral, utilizando um estudo de caso e uma discussão sobre o projeto de implantação de uma instalação de tratamento de itabiritos de baixo teor, denominada ITM-S, a ser instalada em uma empresa mineradora de ferro no Estado de Minas Gerais. Seu objetivo principal foi analisar a viabilidade técnica e econômico-financeira desse projeto, com base nos conceitos existentes na metodologia FEL (Front-End-Loading), associados aos conceitos de sequenciamento de lavra, beneficiamento mineral e economia mineral. Foram analisados, na metodologia, dois cenários do projeto para a escolha das alternativas de rotas de processo: com o uso de separação magnética (cenário 1), e sem a utilização de separação magnética (cenário 2). Os resultados mostraram que o cenário 2 é o mais viável economicamente, devido principalmente a redução do investimento por tonelada produzida, dentre outros fatores. Pretende-se apresentar as várias evoluções nos processos de tratamento de minério de ferro, e apresentar uma metodologia adequada para análise de viabilidade de projetos de tratamento e aproveitamento de minérios de ferro marginais, como a metodologia FEL, associada aos conceitos existentes na engenharia de minas. ____________________________________________________________________________________________________
ABSTRACT: This dissertation describes the current situation and trends related to the exploitation of low-grade iron ore in the mineral industry, to accomplish it, a case study and a discussion on the implementation project of a treatment facility for low grade itabirites called ITM-S, to be installed in an iron ore mining company in the State of Minas Gerais, are presented. The main objective was to analyze the technical and economic-financial feasibility of this project, based on FEL methodology (Front-End- Loading) existing concepts, associated with the mining concepts of sequencing, mineral processing and mineral economics. Using this methodology, two project’s scenarios were analyzed in order to help to choose between two alternative routes: magnetic separation usage (scenario 1), and no usage of magnetic separation (scenario 2). The results showed that scenario 2 is the most economically viable; mainly due to reduction of the investment per ton produced, among other factors. This work intends to present the various evolutions in the iron ore treatment processes, and to present an appropriate methodology for marginal iron ore project feasibility analysis, such as the FEL methodology, associated with the existing concepts in mining engineering.
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Darrigo, Emiliana Ribeiro. "Associação do tecido adiposo medular ósseo, massa óssea e a expressão do receptor tipo 1 dos IGFs em crianças e adolescentes obesos." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/17/17144/tde-10042018-142935/.
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O tecido adiposo e ósseo tem uma íntima relação, desde a origem comum nas células tronco estromais derivadas da medula óssea. Sabe-se que o peso corporal tem estreita correlação com a massa óssea em seres humanos. Porém, ainda não é claro qual componente do peso corporal tem maior influência sobre o ganho de massa óssea e sobre a adiposidade na medula óssea, visto que tanto indivíduos com baixo peso, quanto os obesos, apresentam altas taxas de fraturas. O objetivo deste trabalho foi comparar crianças e adolescentes obesos e eutróficos em relação a composição óssea, adiposidade da medula óssea em coluna lombar (L3), expressão do Receptor tipo 1 de IGF (IGF1R) e concentrações séricas de IGF-I e buscar correlação entre estas variáveis. Para tanto foram avaliados crianças e adolescentes de 10 a 17 anos, divididos em grupo controle e grupo obeso. Esses grupos foram submetidos a avaliação antropométrica, densitometria óssea de coluna lombar e corpo total e ressonância magnética de coluna lombar e abdome total, além de dosagens séricas de parâmetros bioquímicos e hormonais. Os pacientes do grupo obeso apresentaram associação positiva da densidade mineral óssea tanto com massa gorda quanto com massa magra, enquanto que o grupo controle apresentou associação positiva da densidade mineral óssea apenas com a massa gorda. Não houve diferença entre os grupos quanto a adiposidade da medula óssea, nem quanto aos valores de IGF-I, IGFBP3 e expressão do gene do IGF1R.The adipose and bone tissue has an intimate relationship, from the common origin in stromal stem cells derived from the bone marrow. It is known that body weight has a close correlation with bone mass in humans. However, it is still unclear which component of body weight has a greater influence on bone mass gain and adiposity in the bone marrow, since both individuals with low weight and obese have high fracture rates. The objective of this study was to compare obese and eutrophic children and adolescents in relation to bone composition, bone marrow adiposity in the lumbar spine (L3), expression of IGF type 1 receptor (IGF1R) and serum concentrations of IGF-I and to seek correlation between these variables. For this, children and adolescents between 10 and 17 years old were divided into control and obese groups. These groups were submitted to anthropometric evaluation, bone densitometry of the lumbar spine and total body and lumbar spine and total abdominal magnetic resonance, in addition to serum levels of biochemical and hormonal parameters. The patients in the obese group had a positive association of bone mineral density with both fat mass and lean mass while the control group showed a positive association of bone mineral density with fat mass only. There was no difference between the groups regarding bone marrow adiposity, nor regarding IGF-I, IGFBP3 and IGF1R gene expression.
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Martins, Lucelene. "Condições de cristalização de granitos sin- e tardi-orogênicos da porção central do batólito Agudos Grandes, SP, com base em geoquímica de minerais e rochas." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/44/44135/tde-19042007-135922/.
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A química mineral e de rocha e determinações de susceptibilidade magnética (SM) de granitóides sin- e tardi orogênicos (610- 600 Ma) localizados na porção oriental do batólito Agudos Grandes (porção central do Cinturão Ribeira, SE do Brasil) foram utilizadas para determinar as condições de cristalização e as implicações em sua petrogênese. Os granitos sin-orogênicos são metaluminosos e têm índice de cor (IC) entre 8 e 15, dado por hornblenda, biotita, titanita e magnetita (unidade HBgd). As temperaturas liquidus obtidas pelo geotermômetro de saturação em apatita decrescem de 1000 a 950º C com o fracionamento. As temperaturas solidus obtidas pelo geotermômetro hornblenda-plagioclásio, variam de 720 a 800º C e mostram aumento sistemático em direção a leste, refletindo diminuição da a(H2O) dos magmas. As pressões obtidas por geobarometria de Al em hornblenda variam muito pouco (3,6 a 4,5 kbar) mostrando não haver variações significativas no nível de exposição do batólito. Esses granitos cristalizaram sob condições fortemente oxidantes (DNNO ³ + 2), como revelado pela alta SM, pelas composições da biotita e da ilmenita reliquiar e pelo consumo da ilmenita sob fO2 acima do buffer TMQA. Os granitóides tardi-orogênicos (maciço Piedade) variam de metaluminosos a marginalmente peraluminosos. A unidade metaluminosa portadora de titanita e magnetita (BmgT; IC=8) cristalizou sob condições comparáveis às dos granitos sin-orogênicos. As demais unidades são formadas por granitos com biotita e ilmenita (± muscovita e magnetita) e IC variável entre 15 e 5. Essas rochas em geral cristalizaram sob condições mais reduzidas (QFM a DNNO = + 2), como revelado pela SM mais baixa e pela composição de biotita e ilmenita, mas localmente foram afetadas por processos de oxidação pós-magmática. As temperaturas liquidus obtidas a partir do geotermômetro de saturação em apatita para todas as rochas do maciço Piedade são tão elevadas quanto as dos granitos sin-orogênicos. Estimativas de pressão são precárias, mas as composições de muscovitas sugerem valores da ordem de 4 kbar. Os dados obtidos no presente trabalho são consistentes com modelos que admitem um vínculo genético entre os granitos sin- e tardi-orogênicos do batólito Agudos Grandes. Em particular as tendências de variação química contínua das biotitas, com aumento progressivo do componente siderofilita para os granitos com muscovita, paralelas com a diminuição de SM e diminuição de fO2, podem sugerir que diferenças observadas refletem processos de contaminação de magmas metaluminosos por rochas metassedimentares mais reduzidas.Magnetic susceptibility (MS) measurements and mineral and rock chemistry were used to infer crystallization conditions of syn- to late-orogenic (610-600 Ma) granites of the eastern portion of the Agudos Grandes batholith (central Ribeira Belt, SE Brazil). The syn-orogenic granites are metaluminous and have color indices (IC) of 8 to 15 given by hornblende, biotite, titanite and magnetite (unit HBgd). Liquidus temperatures obtained by apatite saturation thermometry decrease slighlty, from 1000 to 950°C with fractionation. Solidus temperatures, derived from hornblende-plagioclase thermometry, raise eastwards in the batholith from 720 to 800° C, reflecting decreasing a(H2O) of the magmas. Pressures derived from Al-in-hornblende barometry are nearly invariable (3.6 to 4.5 kbar), showing that the batholith is exposed at approximately the same level of intrusion along the studied section. These granites crystallized under strongly oxidizing conditions (DNNO ³ + 2), as revealed by high MS, by the compositions of biotite and relict ilmenite, and by ilmenite consumption due to fO2 above the TMQA buffer. The late-orogenic granites (Piedade massif) are metaluminous to marginally peraluminous. The metaluminous unit (BmgT; IC=8) bears titanite and magnetite, and crystalized under conditions comparable to those shown by the syn-orogenic massifs. The remaining units are made up of biotite + ilmenite (± muscovite and magnetite) granites with variable IC (15 to 5). These rocks crystallized mostly under more reduced conditions (QFM to DNNO = + 2), as revealed by lower MS and by the compositions of biotite and ilmenite, but were locally affected by post-magmatic oxidation processes. The liquidus temperatures obtained from apatite saturation thermometry in all granites from the Piedade massif are as high as those of the syn-orogenic massifs. Pressure estimates, based on muscovite compositions, are less reliable, but yield values around 4 kbar. The data obtained in this work are consistent with models which admit a genetic link between the syn-orogenic and the late-orogenic granites of the Agudos Grandes batholith. Continuous chemical variation of biotites, with the siderophyllite component increasing steadily towards the muscovite-bearing granites, and parallel decreasing of MS and fO2 suggest that contamination of metaluminous magmas by more reduced metasediments could explain most of the variation observed.
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Gyllencreutz, Richard. "Holocene and Latest Glacial Paleoceanography in the North-Eastern Skagerrak." Doctoral thesis, Stockholm : Department of Geology and Geochemistry, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-413.
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Farwig, Victoria Jane. "Evaluation of mineral magnetic properties and thermal activation characteristics of soil material in reconstructing post-fire sediment redistribution and fire history, Sydney Basin, Australia." Thesis, Swansea University, 2006. https://cronfa.swan.ac.uk/Record/cronfa43195.
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Badesab, Firoz [Verfasser], Tilo von [Akademischer Betreuer] Dobeneck, and Karin [Akademischer Betreuer] Bryan. "Magnetic mineral enrichment and transport in coastal environments: Tauranga Harbour, Northeastern, New Zealand / Firoz Badesab. Gutachter: Tilo von Dobeneck ; Karin Bryan. Betreuer: Tilo von Dobeneck." Bremen : Staats- und Universitätsbibliothek Bremen, 2012. http://d-nb.info/1072046717/34.
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Rodrigues, Diana Magalhães Cunha. "Prospecção geoquímica: estaurolita, ilmenita e magnetita como minerais traçadores para depósitos do tipo VMS." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=3093.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorConselho Nacional de Desenvolvimento Científico e Tecnológico
A região de Itutinga foi alvo de estudos prospectivos por parte da empresa BP mineração na década de 80, onde foram encontradas mineralizações em lentes de sulfetos metálicos (Zn-Cu-Ag-Fe) associados a rochas komatiíticas peridotíticas e basaltos toleíticos (anfibolitos) do greenstone belts, nas proximidades da fazenda São Jerônimo, enquadrando-se em um depósito do tipo VMS. A partir destas informações encontradas na literatura propôs-se estudar a estaurolita, a magnetita e a ilmenita para, a partir da determinação do seu conteúdo em zinco, indicar a aplicabilidade destes três minerais como traçadores desses tipos de depósitos. Para isso foram coletadas amostras de sedimentos de corrente e concentrados de batéia na região próxima à ocorrência, no entorno da cidade de Itutinga, e também em uma região próxima a cidade de Itumirim, já que existem semelhanças litológicas entre as duas áreas. Os sedimentos de corrente, as frações magnéticas e as frações de 0,3A (separador eletromagnético Frantz) foram enviados para análises químicas por absorção atômica e ICP-OES. Os concentrados de batéia foram descritos, separando-se cristais de estaurolita de cada amostra coletada, e analisando-os em MEV-EDS para determinação da química mineral. Os resultados dos sedimentos de corrente apontaram que os pontos da fazenda São Jerônimo (ME-03, Itutinga 51,7 ppm de Zn) e o ponto do Ribeirão Santa Cruz, (ME-06, Itumirim 36,1 ppm de Zn) foram os que apresentaram melhores resultados, indicando anomalias em zinco nas duas áreas estudadas . As estaurolitas, retiradas dos concentrados de batéia de cada ponto estudado, foram divididas em três conjuntos, de acordo com os teores de ZnO encontrados: 1 - entre 2,96% e 3,25% de ZnO em peso; 2 - entre 2,03% e 2,76% de ZnO em peso; 3 - < 1,67% de ZnO em peso, sendo comparável com outras estaurolitas encontradas em diversos depósitos de Zn do mundo, como Dry River, Austrália e Palmeirópolis Goiás. Assim, as estaurolitas apresentam bons resultados como minerais indicadores na área estudada. Em relação as magnetitas e ilmenitas estudadas, o número de amostras coletadas no presente estudo foram muito pequenas para se ter informações conclusivas sobre o papel destes minerais como traçadores. Por outro lado, os resultados das análises químicas nos concentrados de ilmenita (até 856 ppm de Zn) e nos concentrados de magnetita (até 216 ppm de Zn), indicam a disponibilidade deste metal nas áreas estudadas. Assim, é possível se detectar a presença do zinco por dois meios: através de sedimentos de corrente, através de halos de dispersão química do elemento zinco, e através dos minerais resistatos (estaurolita zincífera, magnetita e ilmenita), a partir de uma dispersão clástica do grão.
The Itutinga region was studied for BP mineration in 80s , where they found sulphide mineralization in lenses (Zn-Cu-Ag-Fe) associated with komatiitic peridotite rocks and tholeitic basalts (amphibolites) of greenstone belts, near of Fazenda São Jerônimo. With this information in the literature the propose is study the staurolite, magnetite and ilmenite for indicating the applicability of these three minerals as tracers of these types of mineralization. For this, samples of stream sediment and panning concentrates in the region near the city of Itutinga, and also in a region near the city of Itumirim. The stream current, magnetic fractions and ilmenite fractions were sent to chemistry analyses (Atomic absorption and ICP-OES), and the panning concentrates were analyzed for the separating of staurolite crystals, and sent to SEM-EDS. The stream sediments results showed that the point of Fazenda São Jerônimo (ME-03, Itutinga 51,7 ppm of Zn) and the point of Ribeirão Santa Cruz (ME-06, Itumirim 36,1 ppm of Zn) were presented the best result. The staurolite of panning concentrates were divided into three groups according to levels of ZnO matched: 1 - between 2.96% and 3.25% by weight of ZnO, 2 - from 2, 03% and 2.76% by weight of ZnO, 3 - <1.67% ZnO by weight, comparable with other staurolite found in many zinc deposits in the world, such as Dry River, Australia and Palmeirópolis Goiás. Thus, the staurolite show good results as indicator minerals in the area. With respect to magnetite and ilmenite concentrates, the number of samples collected in both areas was too small to have conclusive information. On the other hand, the results of the chemical ilmenite (up to 856 ppm Zn) and magnetite (up to 216 ppm Zn), indicate the availability of this metal in the areas studied. Thus, it is possible to detect the presence of zinc by two means: through stream sediments through chemical dispersion halos of zinc, minerals and through resistive minerals (zincian staurolite, magnetite and ilmenite), from a crystal clastic dispersion.
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Velandia, Astrid Siachoque. "Mecanismos de alojamento e deformação da fácies albita granito do plúton madeira, Mina Pitinga (AM)." Universidade Federal do Amazonas, 2015. http://tede.ufam.edu.br/handle/tede/4667.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The albite granite is the latter facies of the A-type Madeira granite with alkaline affinity, which is a special Orosirian pulse of the A-type magmatic event in the Tapajós-Parima Province into Amazon craton. This facies is subdivided in two subfacies, the core albite granite and the border albite granite. The petrographic study allowed identify that the principals constituent minerals of the magmatic phase in these rocks undergone weak solid-state deformation, in which it is found locally feldspars with grain boundary migration, undulate extinction and mechanical twinning, as well as, some elongate crystals of quartz displaying typical chessboard pattern with slip planes preferably in the a-axes, dynamic recrystallization, subgrain rotation and inclusions of albite according to the limits of the crystals. These microstructures in granitic rocks indicate strain rates under intermediated to high temperatures. Geometric and kinematic analysis of the structures in the albite granite showed that: this granitic rock was deformed during a magmatic stage recording the S0 magmatic foliation, which was grouped in two orientations: N67°W/52°E e S79°W/58°N (predominant). The anisotropy of magnetic susceptibility and shape preferred orientation study, confirm the stability of the primary deformation in the albite granite, these results revealed predominantly subcoaxial magnetic and mineral fabrics in both subfácies. Subsequently, the albite granite was affected by brittle deformation through of transcurrent shear zones (ZCA-B) with plunges S70°W/56°N and S23°E/58°W respectively, and dominant dextral strike-slip component associated with the principal shear zone ZCA, as well as, normal faulting (FR) with prevailing attitude S60°E/58°S and normal-sense movement. The progressive petrological evolution and continue structural pattern of the albita granite facies with respect to earlier facies of Madeira granite, define that the emplacement in the upper crust of the different pulses in this granite, was result of nested pluton process controlled by NE-SW trending strike-slip system and predominantly dextral kinematics, which is an expression of regional deformation.
A fácies Albita granito é a fácies mais tardia do granito Madeira de afinidade alcalina a qual é um especial pulso do magmatismo tipo A que se desenvolveu de forma expressiva no período Orosiriano na província Tapajós-Parima no cráton Amazônico. Esta fácies se subdivide em duas subfácies: Albita granito de núcleo e Albita granito de borda. O estudo petrográfico permitiu identificar que os minerais constituintes da fase magmática destas rochas apresentam localmente feições de deformação plástica, cristais de K-feldspato e albita com limites lobados por migração de borda, extinção ondulante e geminação mecânica, assim como fenocristais de quartzo exibindo extinção ondulante em padrão de tabuleiro de xadrez com planos de deslizamento preferencialmente no eixo , recristalização dinâmica, rotação de subgrãos e inclusões de albita e alinhadas segundo os limites dos cristais. Estas microestruturas em rochas graníticas indicam taxas de deformação sob temperaturas intermediárias. Análises geométrica e cinemática das estruturas levantadas em campo nas subfácies do Albita granito, comprovaram que localmente a rocha se deformou ainda num estágio magmático, registrando foliação magmática S0, agrupada em duas orientações: N67°W/52°E e S79°W/58°N (predominante). Os resultados do estudo de anisotropia de susceptibilidade magnética e orientação preferencial de forma avaliam localmente a estabilidade da petrotrama dúctil medida em afloramento e registram tramas magnética e mineral predominantemente subparalelas nas duas subfácies. Posteriormente, o Albita granito foi deformado rúptilmente por zonas de cisalhamento transcorrentes (ZCA-B) orientadas S70°W/56°N e S23°E/58°W, com cinemática dextral dominante associada ao cisalhamento principal ZCA, e por falhamento normal (FR) com atitude predominante S60°E/58°S, sob os efeitos de um campo regional de esforços que se manteve estável durante sua cristalização e deformação. A progressiva evolução petrológica e continuo padrão estrutural da fácies Albita granito com respeito às fácies mais precoces do granito Madeira refletem que o alojamento dos diferentes pulsos magmáticos deste granito na crosta superior, ocorreu associado com processos de nested plutons controlados por um contexto regional de deformação transcorrente com trend NE-SW e cinemática dextral predominante.
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Silva, Luciana Tabajara Parreiras e. "Influência do tecido adiposo, adiposidade da medula óssea e das incretinas sobre a densidade mineral óssea de pacientes com síndrome do intestino curto." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/17/17138/tde-20072018-100203/.
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A Síndrome do Intestino Curto (SIC) é uma doença complexa que ocorre após extensa ressecção do intestino delgado, levando a uma má absorção de nutrientes e fluidos, uma condição que pode causar diarreia, desnutrição e perda de peso graves com alto risco para o desenvolvimento da osteoporose. Estudos recentes mostram existir ampla interação fisiológica do esqueleto com os diversos sistemas, incluindo o metabolismo energético e o trato digestório. Peptídeos originados não só no tecido adiposo, mas também no intestino como as incretinas [GIP (polipeptídeo trópico insulínico dependente de glicose) e GLP1 (peptídeo 1 tipo glucagon)] modulam a atividade de remodelação óssea. O objetivo principal do atual estudo foi avaliar a relação entre os tecidos adiposos subcutâneo (TAS), visceral (TAV), lipídeos intra-hepáticos (LIH), tecido adiposo da medula óssea (TAMO), bem como do GIP, GLP1, e grelina com a densidade mineral óssea (DMO) em pacientes com SIC. Tratase de um estudo observacional prospectivo composto por dois grupos experimentais pareados por altura, idade e sexo: a) o grupo controle (GC) (n = 18; 9M,9F) e b) o grupo de pacientes com SIC, o qual foi avaliado em 2 ocasiões, com intervalo de um ano entre as análises, sendo denominados SIC0 (n = 14; 7M,7F) e SIC1 (n = 11; 6M,5F). Em comparação com o GC, pacientes com SIC ao longo do estudo apresentaram menor DMO e maior LIH e GIP (p< 0,05). Os valores de TAMO, GLP1 e grelina foram similares entre os grupos. O TAMO teve correlação negativa e significativa com DMO de L3 no GC (r= -0,6; p< 0,05), porém, no grupo SIC esta correlação foi positiva, mas sem significância estatística ao longo do estudo: SIC0 (r= 0,45; p= 0,13) e SIC1 (r= 0,45; p= 0,17). LIH associou-se negativamente com DMO do colo do fêmur (R²= 0,16; p< 0,05) e quadril total (R²= 0,27; p< 0,05). Existe alta prevalência de osteoporose em pacientes com SIC. No entanto, não se observou nem expansão de TAMO e nem relação negativa da DMO com o TAMO. O acesso a calorias parece afetar positivamente a relação entre TAMO e massa óssea. A deposição hepática de lipídeos parece afetar negativamente a massa óssea de pacientes com SIC.Short bowel syndrome (SBS) is a complex disease that occurs after extensive resection of the small intestine leading to malabsorption of nutrients and fluids, a condition that can cause severe watery diarrhea, dehydration and acute weight loss, developing high risk for the appearance of osteometabolic disease. Studies have shown the progress on the physiological interaction of the skeleton with the various systems, including energetic metabolism and the gastrointestinal tract. Peptides originated not only in adipose tissue but also in the intestine such as incretin [GIP (Glucose-dependent insulinotropic polypeptide) and GLP1 (glucagonlike peptide 1) modulate bone remodeling activity. The main objective of the current study was to evaluate the influence of subcutaneous (SAT), visceral (VAT) adipose tissue, intrahepatic lipids (IHL), bone marrow fat adipose tissue (MAT), as well as the influence of GIP, GLP1, and ghrelin on the bone mineral density (BMD) of SBS patients. It is a prospective observational study composed by two experimental groups matched by height, age and sex: a) the control group (CG) (n = 18; 9M,9F) and b) the SBS group which were evaluated in two occasions with a period between analyzes of one year: named SBS0 (n = 14; 7M,7F) and SBS1 (n = 11; 6M,5F). Compared to CG, SBS patients throughout the study had significantly lower BMD and elevated IHL and GIP (p< 0.05). Values of MAT, GLP1 and ghrelin were similar between groups. MAT was negatively and significantly correlated with L3 BMD in the CG (r = -0.6; p< 0.05) and positively correlated, but not significant with L3 BMD in the SBS group throughout the study: SBS0 (r= 0.45; p= 0.13) and SBS1 (r= 0.45; p= 0.17). IHL was negatively and significantly associated with femoral neck BMD (R²= 0.16; p< 0.05) and total hip BMD (R²= 0.27; p< 0.05). The occurrence of osteoporosis is frequent in SBS patients, but MAT is not increased in these patients and had positive correlation with BMD, although not significant. Access to calories seems to positively affect the relationship between MAT and bone mass. IHL appear to negatively affect bone mass in SBS patients.
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Whiting, Thomas H. "A study of the lithology and structure of the eastern Arunta Inlier based on aeromagnetic interpretation : a lithological subdivision and structural history of the eastern Arunta Inlier, with particular emphasis on the relationship between magnetic mineral petrogenesis, rock magnetism and aeromagnetic signature /." Title page, contents and abstract only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09phw6125.pdf.
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Li, Zhengnan. "Vortex magnetic separation (VMS)." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292447.
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Nouvel, Guy. "Etude par spectrometrie raman des phonons et des excitations electroniques dans les trichalcogenures d'uranium." Toulouse 3, 1987. http://www.theses.fr/1987TOU30056.
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Etude des phonons a k = 0 de ux::(3) (x = s, se, te) quasi-unidimensionnels par diffusion raman a 300 k. L'analyse des spectres a ete completee par un calcul de dynamique de reseau fonde sur un modele d'interaction a deux corps et a courte portee. L'etude des composes suggere l'existence d'une transition magnetique, vers 50 k dans le seleniure, vers 10 k pour le tellurure. Des structures dues a des transitions electroniques au sein de la configuration 5f**(2) de l'ion u**(4+) ont ete mises en evidence dans le sulfure et le seleniure
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Leißner, Thomas. "Beitrag zur Kennzeichnung von Aufschluss- und Trennerfolg am Beispiel der Magnetscheidung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-206695.
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In der Arbeit werden Aufschluss- und Sortierergebnisse miteinander kombiniert, um die Anreicherung des Wertstoffs unter Berücksichtigung beider Teilprozesse auf einer vergleichbaren Basis bewerten zu können. Hierfür werden der Literatur vorhandene Modelle entnommen und erweitert, wodurch sich neuartige Parameter definieren lassen.
Am Beispielsortierschritt Magnetscheidung wird anhand zweier unterschiedlicher Erze die Beurteilung der Teilprozesse auf Grundlage des vorgeschlagenen Vorgehens dargestellt. Mit Hilfe der Untersuchung der magnetischen Eigenschaften der Erze kann der Einfluss des gewählten Merkmals auf den Verlauf der berechneten Grenzkurven gezeigt werden.
Weiterhin erfolgt eine Darstellung der Möglichkeiten durch die Nutzung moderner mineralogischer Analysemethoden zur Berechnung von Mineralsuszeptibilitäten, basierend auf Aufschluss- und Suszeptibilitätsmessungen von Merkmalklassen, sowie das direkte Berechnen von Trennfunktionen mit Hilfe von Aufschlussanalysen der Trennprodukte.
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Cavanough, Gary. "Measurement of magnetic susceptibility in titanium minerals processing /." St. Lucia, Qld, 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17774.pdf.
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Jones, J. M. "Magnetic minerals and heavy metals in ombrotrophic peat." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372671.
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Dunsford, Helen Mary. "The response of alluvial fans and debris cones to changes in sediment supply, upland Britain." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/1468/.
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Boehm, Josef. "A study of the open gradient magnetic separation method." Thesis, University of Salford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291728.
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Swarts, Arnoldus Carel. "The Influence of magnetic fields on the flotation of sulphide minerals." Diss., Pretoria : [s.n.], 2001. http://upetd.up.ac.za/thesis/available/etd-02192007-094826.
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Goss, K. J. "Chemical remanent magnetisation and phase transformations in iron oxide minerals." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233951.
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Chemical remanent magnetisation (CRM) occurs as the result of the acquisition of remanence by a rock through chemical change or mineral growth. Despite the important role CRM plays in rock magnetic and palaeomagnetic processes (as a mechanism by which rocks acquire a primary remanence or as a feature of post- depositional alteration) there are few studies of this process to date. This dissertation investigates the effect of phase and chemical change on the magnetic and remanence carrying properties of some geologically important iron oxide minerals. The mineral systems studied are: the goethite-hematite, the magnetite-maghemile-hematite and the lepidocrocite-maghemite-hematite systems. The mineralogy of these systems is studied using transmision electron microscopy, thermogravimetry and x-ray diffraction methods. A transformation mechanism for the dehydration reaction of goethite is presented. The cation distribution of maghemite and its intrinsic magnetic properties are investigated. The process of CRM is simulated in the systems goethite-hematite and lepidocrocite-maghemite-hematite and the results correlated with theoretical predictions of CRM intensity, blocking volume and their dependence on mineral growth rate. A self-reversal in the maghemite-hematite system is reproduced. The low temperature oxidation of magnetite to maghemite and hematite (for example in basalts) and the low temperature dehydration reactions of goethite and lepidocrocite (as occur, for example, in sediments) are important mineral transformations. The results and conclusions of this study are extrapolated to geological environments and time scales, in particular with reference to red bed palaeomagnetism.
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Gonzalez, Lucena Fedora. "Mineral Magnetism of Environmental Reference Materials: Iron Oxyhydroxide Nanoparticles." Thesis, Université d'Ottawa / University of Ottawa, 2010. http://hdl.handle.net/10393/19608.
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Iron oxyhydroxides are ubiquitous in surface environments, playing a key role in many biogeochemical processes. Their characterization is made challenging by their nanophase nature. Magnetometry serves as a sensitive non-destructive characterization technique that can elucidate intrinsic physical properties, taking advantage of the superparamagnetic behaviour that nanoparticles may exhibit. In this work, synthetic analogues of common iron oxyhydroxide minerals (ferrihydrite, goethite, lepidocrocite, schwertmannite and akaganéite) are characterized using DC and AC magnetometry (cryogenic, room temperature), along with complementary analyses from Mössbauer spectroscopy (cryogenic, room temperature), powder X-ray diffraction and scanning electron microscopy. It was found that all of the iron oxyhydroxide mineral nanoparticles, including lepidocrocite, schwertmannite and akaganéite were superparamagnetic and therefore magnetically ordered at room temperature. Previous estimates of Néel temperatures for these three minerals are relatively low and are understood as misinterpreted magnetic blocking temperatures. This has important implications in environmental geoscience due to this mineral group’s potential as magnetic remanence carriers. Analysis of the data enabled the extraction of the intrinsic physical parameters of the nanoparticles, including magnetic sizes. The study also showed the possible effect on these parameters of crystal-chemical variations, due to elemental structural incorporation, providing a nanoscale mineralogical characterization of these iron oxyhydroxides. The analysis of the intrinsic parameters showed that all of the iron oxyhydroxide mineral nanoparticles considered here have a common magnetic moment formation mechanism associated with a random spatial distribution of
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uncompensated magnetic spins, and with different degrees of structural disorder and compositional stoichiometry variability, which give rise to relatively large intrinsic magnetization values. The elucidation of the magnetic nanostructure also contributes to the study of the surface region of the nanoparticles, which affects the particles’ reactivity in the environment.