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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Mineraliseringar utmed REE-linjen i sydvästra Bergslagen

Linnros, Henrik January 2014 (has links)
This paper briefly summarizes Bergslagen as a bedrock province in order to give background to the genesis and presence of REE-bearing minerals (short for Rare Earth Elements) in the region. These mineralizations mainly occur along the REE-line, a line aproximately a hundred kilometers in length between Norberg in the north and Nora in the south with a width of a few kilometers. Situated in the southwest of Bergslagen it is currently one of only a few places in Sweden where REE-bearing iron oxide mineralizations are potentially economically viable for mining. Ore microscopy has been conducted in order to characterize an ore sample from Myrbacksfältet, one of few sulphide rich iron oxide mineralizations within the REE-line. Additionally, an electron microscope analysis of a sample from Stålklockan, a suspected REE-bearing mineralization also within the REE-line was confirmed by EDS (short for Energy Dispersive Spectrum) analysis. An interactive map has been made of the REE- line to aid with visualization in an attempt to collect all known geospatial-, mineral-  and bedrock information in one place. The map is available in PDF format in conjunction with this text. A static version of this map is presented under 4.1 (REE-linjen). / Berggrundsprovinsen Bergslagens regionala geologi beskrivs inledningsvis för att ge bakgrund till de fyndigheter av REE-förande mineral (eng. Rare Earth Elements; Sällsynta jordartsmetaller) som förekommer utmed en ungefär hundra kilometer lång och ett par kilometer bred zon. Detta geografiskt och mineralogiskt avgränsade område kallas REE-linjen och ligger i sydvästra Bergslagen. I detta område mellan Norberg i norr och Nora i söder finns idag några av de få potentiellt ekonomiskt brytbara fyndigheterna av REE-förande mineral i Sverige vilket har gjort en kartkonstruktion vari spatiell-, mineralogisk-, och berggrundsdata över området finns sammanställd meningsfull. En sådan karta har gjorts i ArcGIS och presenteras i interaktivt PDF format i anslutning till texten. Malmmikroskopisk karaktärisering av en sulfidrik järnmalm från Myrbacksfältet i REE-linjen, såväl som en elektronmikroskopisk EDS (Energy Dispersive Spectrum) analys av ett prov från Stålklockan i Riddarhyttans malmfält har genomförts.
2

From Bedrock to Porcelain : A study regarding the history of porcelain, Ytterby mine and the discovery of yttrium in Sweden

Kärrström, Timmy January 2017 (has links)
Porcelain is a translucent vitreous material that consists of clay (kaolin), feldspar and quartz which has been mixed and heated together to cause a metamorphic reaction. In Sweden, the Porcelain industry was established in 1726 at Rörstrands castle in Stockholm and is today one of the oldest industries in Europe to produce porcelain. Around the 1790’s Rörstrand got its feldspars and quartz from the Ytterby mine that was located at Resarö in Stockholm’s archipelago making the raw material somewhat easy to access. Rörstrand owned the mine in the 1850’s to 1926. During the time Ytterby mine was active, an amateur geologist by the name of Carl Axel Arrhenius, discovered an unusual black mineral in the quarry ore in 1787 which later led to the discovery of 8 new rare earth elements (REE) with the help of several Swedish chemists throughout time. These elements are Yttrium, Ytterbium, Gadolinium, Terbium, Thulium, Erbium, Holmium and scandium. This study will focus on the Swedish porcelain industry and how it has evolved throughout history and Rörstrand’s role in the discovery of yttrium.
3

On fusion-simple groups related to ²F?(2) /

Assa, Steven Brent January 1974 (has links)
No description available.
4

Relative REE abundances of porewater in Pacific pelagic sediment: estimation by equilibrium calculations based on REE composition of Mn-oxide and apatite components

TAKEBE, Masamichi, YAMAMOTO, Koshi 25 December 2007 (has links)
No description available.
5

Stable isotope systematics of skarn-hosted REE-silicate - magnetite mineralisations in central Bergslagen, Sweden

Sahlström, Fredrik January 2014 (has links)
The metasupracrustal-hosted, often polymetallic REE-Fe-deposits of Bastnäs-type are found along the “REE-line” in the Palaeoproterozoic Bergslagen ore province, south central Sweden. They essentially comprise REE silicate-bearing magnetite skarn mineralisations with variable contents of other metals. Even though these deposits have been important for mining and research for centuries, their origin still remains unclear. In this study, samples from 10 different deposits along the REE-line have been charactarised as to mineralogy, petrography and bulk geochemistry, in addition to their isotope systematics. Mineral separates of magnetite and, when present, co-existing quartz or carbonates have been analysed for their oxygen and (for carbonates) carbon isotope compositions, in order to put constraints on the sources for metals and fluids in these deposits. Magnetites have δ18O-values of -1.79 to 1.12 ‰, while quartzes lie between 7.19 and 8.28 ‰. Carbonates have δ18O-values between 5.77 and 7.15 ‰ and δ13C-values between -5.35 and -3.32 ‰. Thermometric calculations based on mineral pairs (magnetite-quartz, magnetite-calcite/dolomite), combined with available fluid inclusion data, indicate formation of primary magnetite assemblages between c. 650 to 400 °C. At these temperatures, magnetites from some of the deposits would have been in equilibrium with a magmatic fluid (δ18O = 6-8 ‰), while magnetites from other deposits would have been in equilibrium with fluids of lower δ18O (4-6 ‰). Oxygen and carbon isotope trends in carbonates can be explained by interaction between original host carbonates and a fluid of magmatic composition. The combined results indicate that the Bastnäs-type magnetite-REE mineralisations were deposited from an originally magmatic fluid at relatively high temperatures. At local scale, variable modification of the fluid isotopic composition can be explained by mixing with seawater-dominated fluids.
6

Vidaus degimo variklių alternatyvių degalų efektyvumo lyginamoji anlizė / The comparatyve analysis of efficiency of alternative fuel for engines of internal combustion

Dromantas, Marius 27 June 2005 (has links)
This article presents the comparative bench testing results of a naturally aspirated, four stroke, four cylinder, water cooled, direct injection Diesel engine when runing on Diesel fuel and shale oil that is produced in Estonia from local oil Shale. The purpose of this research is to investigate the possibility of practical usage of the shale oil as the alternative fuel for a high speed Diesel engine as well as to evaluate the combustion efficiency, brake specific fuel consumption, emission composition changes and the smoke opacity of the axhausts.
7

The Ytterby mine - A historical review and an evaluation of its suggested spatial coupling to multiple sclerosis (MS)

Sjöberg, Susanne January 2012 (has links)
The Ytterby mine is located on Resarö island in the Stockholm archipelago. Mainly feldspars but also quartz were historically quarried in the mine, which is also the place of discovery of seven rare earth elements (REE). During the cold war era, the mine shaft was used as a diesel and jet fuel deposit for the Swedish Armed Forces. Recently, a spatial coupling between multiple sclerosis (MS), a chronic neurodegenerative disease in the central nervous system, prevalence and the quarry has been suggested. Previous studies show that adverse neurological health effects are associated with oral intake of REEs and there is support for a coupling between ionizing radiation and MS. The extent and character of health effects as a result of exposure to petroleum products are still debated. However, a substantial number of scientific reports support a coupling between neurodegenerative health effects and toxic constituents of jet fuels such as benzene, toluene, and n-hexane. My data show that a possible overrepresentation of MS patients within the Ytterby postal code area could be an indication of a spatial coupling between the mine and MS. Such a possible coupling could be associated with the REEs present in the local rocks, with the previous storage of diesel or jet fuel MC-77 in the mine and/or with zones of high natural radioactivity in the area. Water samples collected in 15 wells in the Ytterby village show traces of five REEs, i.e. scandium (Sc), yttrium (Y), lanthanum (La), neodymium (Nd) and samarium (Sm) and the majority of sample locations at low ground elevation show contamination of diesel which is the most recent fuel stored in the mine. Moreover, results from an analysis of a black substance leaking out of cracks in the mine corridors confirm that REEs are present in substantial concentrations in the local rocks and also appear to be mobile. This should be taken into account when considering a potential contamination of the local water supply. Measurements of natural radioactivity have also been made around the contours of the quarry and zones of high ionizing radiation have been identified. By using these zones of high ionizing radiation as a proxy for rare minerals containing rare earth elements, I further suggest that the REE occurrences are highly localized around the quarry and could be associated with, or remobilized by, younger faults.  My data show that a full investigation is warranted of a possible spatial coupling between neurological health issues, MS being one of them, and the mine.
8

A mineralização de parisita – (Ce) associada ao carbonatito Fazenda Varela (Correia Pinto, SC).

Manfredi, Tamara Reginatto January 2013 (has links)
O carbonatito Fazenda Varela é um ferrocarbonatito que possui altos teores de ETR (>1%), que são elementos considerados estratégicos por muitos países devido à importância econômica. Este carbonatito faz parte do distrito alcalino de Lages (SC), que possui idade entre 63 e 81 ± 8 Ma. A rocha ocorre na forma de veios que intrudem os sedimentos da Formação Rio Bonito (Bacia do Paraná), formando brechas metassomatizadas. A mineralogia magmática do carbonatito é composta principalmente por ankerita e ferrodolomita, além de pirita, ortoclásio e quartzo. O ferrocarbonatito foi afetado por eventos tardi a pós-magmáticos, que gerou domínios hidrotermais, onde se depositaram barita, apatita, quartzo, calcita, ferrodolomita e parisita-(Ce). A parisita-(Ce) é o principal mineral de ETR e não possui fluorita associada, diferentemente dos outros depósitos de fluorcarbonatos do mundo. A parisita-(Ce) é tardia, depositada em meio aos domínios hidrotermais e intersticial a todos os minerais. Nas imagens ao MEV é possível identificar que este mineral forma policristais fibrorradiados bem desenvolvidos com crescimento sintaxial entre parisita-(Ce) e synchysita-(Ce). Este crescimento pode ser identificado nestas imagens pelas bandas brancas e cinza, com proporções de Ca e ETR diferentes em cada banda. A composição média do policristal de parisita-(Ce) apresenta excesso de Ca e deficiência de ETR e de F em relação a uma composição ideal, devido ao crescimento sintaxial. O padrão de ETR da parisita-(Ce) é semelhante ao das amostras de carbonatito. Este mineral se formou em meio com baixa atividade de F e altas atividades de Ca e CO3, a partir de um fluido hidrotermal ascendente, que interagiu intensamente com o carbonatito, ocasionando a partição preferencial dos ETRL provavelmente na forma de complexos clorados. Sua cristalização pode ter ocorrido pelo aumento na atividade de HCO3- pela dissolução do carbonato primário ou pela elevação do pH pelo aporte de água da rocha encaixante quartzo-feldspática. / The Fazenda Varela carbonatite is a ferrocarbonatite which has high contents of REE (> 1%), that are considered by many countries as strategic elements due to its economic importance. This carbonatite is part of the Lages alkaline district (SC) witch age is between 63 and 81 ± 8 Ma. The rock occurs as veins cutting the sediments of the Rio Bonito Formation (Paraná Basin) forming a metasomatized breccia. The magmatic mineralogy of the carbonatite is composed mainly by ankerite and ferrodolomite, together pyrite, orthoclase and quartz. The ferrocarbonatite was affected by late to post-magmatic events that generated hydrothermal areas where barite, apatite, quartz, calcite, ferrodolomite and parisite-(Ce) were deposited. The parisite-(Ce) is the main REE mineral, and without associated fluorite, different to others fluorcarbonates deposits of the world. The parisite-(Ce) is a late mineral, and was deposited in hydrothermal areas among all minerals. With the SEM images was possible identify that this mineral form well developed fibroradiated polycrystals with sintaxial growth between parisite-(Ce) and synchysite-(Ce). This growth can be identified in SEM images by their gray and white bands, with different Ca and REE ratios in each band. The average composition of the parisite-(Ce) polycrystal presents excess of Ca and deficiency of REE and F in relation to an ideal composition, due to their sintaxial growth. The pattern of the REE parisita-(Ce) is similar to those from the carbonatite samples. This mineral was formed in an environment with low F activity and high activities of Ca and CO3, from a rising hydrothermal fluid, which interacted strongly with carbonatite, resulting in the preferential partitioning of LREE, probably as chlorinated complexes. The parisite-(Ce) crystallization may have occurred by increasing HCO3 activity by primary carbonate dissolution or by the pH rising do to the contribution of water from the quartz-feldspar host rock.
9

A mineralização de parisita – (Ce) associada ao carbonatito Fazenda Varela (Correia Pinto, SC).

Manfredi, Tamara Reginatto January 2013 (has links)
O carbonatito Fazenda Varela é um ferrocarbonatito que possui altos teores de ETR (>1%), que são elementos considerados estratégicos por muitos países devido à importância econômica. Este carbonatito faz parte do distrito alcalino de Lages (SC), que possui idade entre 63 e 81 ± 8 Ma. A rocha ocorre na forma de veios que intrudem os sedimentos da Formação Rio Bonito (Bacia do Paraná), formando brechas metassomatizadas. A mineralogia magmática do carbonatito é composta principalmente por ankerita e ferrodolomita, além de pirita, ortoclásio e quartzo. O ferrocarbonatito foi afetado por eventos tardi a pós-magmáticos, que gerou domínios hidrotermais, onde se depositaram barita, apatita, quartzo, calcita, ferrodolomita e parisita-(Ce). A parisita-(Ce) é o principal mineral de ETR e não possui fluorita associada, diferentemente dos outros depósitos de fluorcarbonatos do mundo. A parisita-(Ce) é tardia, depositada em meio aos domínios hidrotermais e intersticial a todos os minerais. Nas imagens ao MEV é possível identificar que este mineral forma policristais fibrorradiados bem desenvolvidos com crescimento sintaxial entre parisita-(Ce) e synchysita-(Ce). Este crescimento pode ser identificado nestas imagens pelas bandas brancas e cinza, com proporções de Ca e ETR diferentes em cada banda. A composição média do policristal de parisita-(Ce) apresenta excesso de Ca e deficiência de ETR e de F em relação a uma composição ideal, devido ao crescimento sintaxial. O padrão de ETR da parisita-(Ce) é semelhante ao das amostras de carbonatito. Este mineral se formou em meio com baixa atividade de F e altas atividades de Ca e CO3, a partir de um fluido hidrotermal ascendente, que interagiu intensamente com o carbonatito, ocasionando a partição preferencial dos ETRL provavelmente na forma de complexos clorados. Sua cristalização pode ter ocorrido pelo aumento na atividade de HCO3- pela dissolução do carbonato primário ou pela elevação do pH pelo aporte de água da rocha encaixante quartzo-feldspática. / The Fazenda Varela carbonatite is a ferrocarbonatite which has high contents of REE (> 1%), that are considered by many countries as strategic elements due to its economic importance. This carbonatite is part of the Lages alkaline district (SC) witch age is between 63 and 81 ± 8 Ma. The rock occurs as veins cutting the sediments of the Rio Bonito Formation (Paraná Basin) forming a metasomatized breccia. The magmatic mineralogy of the carbonatite is composed mainly by ankerite and ferrodolomite, together pyrite, orthoclase and quartz. The ferrocarbonatite was affected by late to post-magmatic events that generated hydrothermal areas where barite, apatite, quartz, calcite, ferrodolomite and parisite-(Ce) were deposited. The parisite-(Ce) is the main REE mineral, and without associated fluorite, different to others fluorcarbonates deposits of the world. The parisite-(Ce) is a late mineral, and was deposited in hydrothermal areas among all minerals. With the SEM images was possible identify that this mineral form well developed fibroradiated polycrystals with sintaxial growth between parisite-(Ce) and synchysite-(Ce). This growth can be identified in SEM images by their gray and white bands, with different Ca and REE ratios in each band. The average composition of the parisite-(Ce) polycrystal presents excess of Ca and deficiency of REE and F in relation to an ideal composition, due to their sintaxial growth. The pattern of the REE parisita-(Ce) is similar to those from the carbonatite samples. This mineral was formed in an environment with low F activity and high activities of Ca and CO3, from a rising hydrothermal fluid, which interacted strongly with carbonatite, resulting in the preferential partitioning of LREE, probably as chlorinated complexes. The parisite-(Ce) crystallization may have occurred by increasing HCO3 activity by primary carbonate dissolution or by the pH rising do to the contribution of water from the quartz-feldspar host rock.
10

A mineralização de parisita – (Ce) associada ao carbonatito Fazenda Varela (Correia Pinto, SC).

Manfredi, Tamara Reginatto January 2013 (has links)
O carbonatito Fazenda Varela é um ferrocarbonatito que possui altos teores de ETR (>1%), que são elementos considerados estratégicos por muitos países devido à importância econômica. Este carbonatito faz parte do distrito alcalino de Lages (SC), que possui idade entre 63 e 81 ± 8 Ma. A rocha ocorre na forma de veios que intrudem os sedimentos da Formação Rio Bonito (Bacia do Paraná), formando brechas metassomatizadas. A mineralogia magmática do carbonatito é composta principalmente por ankerita e ferrodolomita, além de pirita, ortoclásio e quartzo. O ferrocarbonatito foi afetado por eventos tardi a pós-magmáticos, que gerou domínios hidrotermais, onde se depositaram barita, apatita, quartzo, calcita, ferrodolomita e parisita-(Ce). A parisita-(Ce) é o principal mineral de ETR e não possui fluorita associada, diferentemente dos outros depósitos de fluorcarbonatos do mundo. A parisita-(Ce) é tardia, depositada em meio aos domínios hidrotermais e intersticial a todos os minerais. Nas imagens ao MEV é possível identificar que este mineral forma policristais fibrorradiados bem desenvolvidos com crescimento sintaxial entre parisita-(Ce) e synchysita-(Ce). Este crescimento pode ser identificado nestas imagens pelas bandas brancas e cinza, com proporções de Ca e ETR diferentes em cada banda. A composição média do policristal de parisita-(Ce) apresenta excesso de Ca e deficiência de ETR e de F em relação a uma composição ideal, devido ao crescimento sintaxial. O padrão de ETR da parisita-(Ce) é semelhante ao das amostras de carbonatito. Este mineral se formou em meio com baixa atividade de F e altas atividades de Ca e CO3, a partir de um fluido hidrotermal ascendente, que interagiu intensamente com o carbonatito, ocasionando a partição preferencial dos ETRL provavelmente na forma de complexos clorados. Sua cristalização pode ter ocorrido pelo aumento na atividade de HCO3- pela dissolução do carbonato primário ou pela elevação do pH pelo aporte de água da rocha encaixante quartzo-feldspática. / The Fazenda Varela carbonatite is a ferrocarbonatite which has high contents of REE (> 1%), that are considered by many countries as strategic elements due to its economic importance. This carbonatite is part of the Lages alkaline district (SC) witch age is between 63 and 81 ± 8 Ma. The rock occurs as veins cutting the sediments of the Rio Bonito Formation (Paraná Basin) forming a metasomatized breccia. The magmatic mineralogy of the carbonatite is composed mainly by ankerite and ferrodolomite, together pyrite, orthoclase and quartz. The ferrocarbonatite was affected by late to post-magmatic events that generated hydrothermal areas where barite, apatite, quartz, calcite, ferrodolomite and parisite-(Ce) were deposited. The parisite-(Ce) is the main REE mineral, and without associated fluorite, different to others fluorcarbonates deposits of the world. The parisite-(Ce) is a late mineral, and was deposited in hydrothermal areas among all minerals. With the SEM images was possible identify that this mineral form well developed fibroradiated polycrystals with sintaxial growth between parisite-(Ce) and synchysite-(Ce). This growth can be identified in SEM images by their gray and white bands, with different Ca and REE ratios in each band. The average composition of the parisite-(Ce) polycrystal presents excess of Ca and deficiency of REE and F in relation to an ideal composition, due to their sintaxial growth. The pattern of the REE parisita-(Ce) is similar to those from the carbonatite samples. This mineral was formed in an environment with low F activity and high activities of Ca and CO3, from a rising hydrothermal fluid, which interacted strongly with carbonatite, resulting in the preferential partitioning of LREE, probably as chlorinated complexes. The parisite-(Ce) crystallization may have occurred by increasing HCO3 activity by primary carbonate dissolution or by the pH rising do to the contribution of water from the quartz-feldspar host rock.

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