03 Fakultät Chemie
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Item Open Access Charakterisierung umweltneutraler, natürlicher eisenhaltiger Sauerstoffträger für Chemical-Looping-Combustion (CLC)-Kraftwerke(2018) Schopf, Alexander; Massonne, Hans-Joachim (Prof. Dr.)Chemical Looping Combustion (CLC) ist eine großtechnische Verbrennungstechnologie zur Stromerzeugung mittels Wirbelschichtreaktoren unter Verwendung von Feststoffen anstelle von Luft als Sauerstoffträger. CLC zählt zu den CO2-Sequestrierungsverfahren für Carbon Dioxide Capture and Storage (CCS). Das Rauchgas besteht hauptsächlich aus Wasserdampf und Kohlenstoffdioxid, die Produktion von Stickoxiden wird prozessbedingt vermieden, der Wirkungsgradverlust liegt bei theoretisch 2 bis 3 %. Das bislang als Sauerstoffträger für CLC verwendete Mineral Ilmenit ist im Vergleich mit anderen Erzen relativ selten. Synthetisch hergestellte Sauerstoffträger sind dagegen teurer und daher unwirtschaftlich. Ziel der Arbeit war die Identifikation umweltneutraler natürlicher Sauerstoffträger für CLC-Kraftwerke die sowohl gut verfügbar sind als auch wirtschaftliche Alternativen darstellen. Für die Untersuchungen wurden die Gütekriterien der Effektivität für CLC und Kraftwerkseignung zu Grunde gelegt: gute Abriebfestigkeit, hohe Reaktivität mit Brenngasen bei 900 °C, insbesondere Methan, hohe Sauerstofftransportkapazität mit ca. 10 % Masseverlust bei der Reduktion, hohe Reaktivität mit Luftsauerstoff bei der Oxidation und eine Temperaturstabilität von mindestens 1000 °C unter oxidierenden Bedingungen. Weiteres Forschungsziel war die Aufklärung der ablaufenden Prozesse der Reduktions- bzw. Oxidations-Reaktionen bei den einzelnen Sauerstoffträgern unter simulierten Kraftwerksbedingungen. Mit der Entwicklung eines systematischen, für alle Sauerstoffträger anwendbaren, Untersuchungsgangs wurde eine fundamentale Methode zur Visualisierung der inhärenten chemischen Reaktionen bei wiederholender sukzessiver Reduktion und Oxidation geschaffen. Die experimentelle Versuchsabfolge gliederte sich in vier Teile: Vorbereitung und mineralogische Untersuchung zur Beschreibung des Ausgangsmaterials, Vorstudie zur Überprüfung der Temperaturstabilität von 1000 °C in der Thermowaage (TGA), Hauptstudie mit Simulation von CLC in der TGA und eine Vergleichsstudie unter Kraftwerksbedingungen im Versuchskraftwerk des Instituts für Feuerungs- und Kraftwerkstechnik der Universität Stuttgart zur Korrelation der Ergebnisse der Hauptstudie. Unter ihrer Anwendung wurden die hier einbezogenen Proben charakterisiert, wobei sich sieben von 12 Proben der Hauptstudie (aufgrund der formulierten Anforderungskriterien) als Sauerstoffträger besonders geeignet erwiesen: Magnetiterz, Maphopha (RSA), Magnetiterz, Thạch Khê (SGA), Roter Glaskopf, Toulkine (IMI), MIOX ME400, Waldenstein (KMI), Hämatiterz, Norwegen (DH), Bändereisenerz, Bogalatladi (RSA) und Ilmeniterz, Capel (IFK). Bei sehr lang gewählten Reduktionszeiten mit Brenngas entstanden zudem Varietäten des Kohlenstoffs, wie bspw. amorpher Kohlenstoff, Graphit und Graphen, als Abscheidung aus der Gasphase auf den Sauerstoffträgeroberflächen. Dies gibt Anlass zu weiteren Forschungen.Item Open Access Petrological and geochemical contribution to the origin of jadeitite and associated rocks of the Tawmaw Area, Kachin State, Myanmar(2009) Nyunt, Thet Tin; Massonne, Hans-Joachim (Prof. Dr.)Jade is the trade term for the jewellers but mineralogically two types of jade exist: jadeite (pyroxene end-member NaAlSi2O6); and Ca-amphibole (end-member Ca2Mg5Si8O10 (OH)2), nephrite. Jadeite jade (petrological term: jadeitite) is rarer and also more valuable than nephrite jade. Jadeitite is found only in a few countries including Myanmar, Japan and Guatemala where corresponding deposits are associated with major strike slip faults and high-pressure tectonic zones and always associated with serpentinites and high-pressure rocks. The recent geotectonic evolution of Myanmar is related to the India-Asia collision. In the central part of Myanmar the N-S trending Central Burma Basin is located which is filled with Eocene to Plio-Quaternary sediments. The sedimentary association is related to a fore-arc basin which resulted from northeastward-directed subduction of the Bengal oceanic crust beneath Myanmar. The study area, the Tawmaw area, is located in the northern part of the Central Burma Basin at the western part of the Sagaing strike-slip fault zone around 15 km northwest of the city of Pharkant. This area is part of the so-called “jade mines area” or “jade belt” which extends over ca. 2600 km2. Glaucophane schist is the most common rock which is exposed together with epidote schist in the eastern part of the Tawmaw area where serpentinized peridotite-dunite and jadeite-bearing rocks also occur. Garnet-mica schists also occur in tectonic contact with the serpentinized peridotite-dunite in the western part of the Tawmaw area. A larger elongated ultramafic body of late Cretaceous to early Eocene (dismembered) ophiolite unit occur in the central part. Jadeitite is found as vein-like or lens-shape bodies in the serpentinized peridotite-dunite body. In this jadeitite-bearing unit it is possible to distinguish between two main zones. The Outer Zone, occurring at the border of ultramafic rocks, is made up of thin layers chlorite, actinolite schists and amphibole felses (so-called wall rocks), which can, however, also lack. Jadeite and kosmochlor are also included in the amphibole felses together with chromite. The Central Zone is composed of the vein-like or massive lenses of jadeitite but can also contain albitite. The petrological study revealed that the supply of chromium in jadeite is from chromite of the former (and still adjacent) peridotite. This can be clearly seen in maw-sit-sit and amphibole felses where kosmochlor formed from destabilized chromite keeping the size of the original chromite grain. Thus, chromium is immobile in contrast to strongly mobile Na. Moreover, it means that sperpentinite and not the country rocks surrounding serpentinite was replaced by the wall-rocks. In the (nearly) pure jadeitite, vesuvianite, identified by RAMAN-spectroscopy, was found for the first time in one sample only. Vesuvianite normally occurs in low-pressure environments such as contact aureoles, rodingite/metarodingite, and skarns. This study shows that this phase can also appear in a high-pressure environment. The mineral assemblage of vesuvianite + end-member jadeite does not show any indication for non-equilibrium. The composition of this vesuvianite is characterized by up to 1.5 wt.% Na2O that is higher than for vesuvianite described from elsewhere. A major mechanism to incorporate Na into vesuvianite is the charge-balanced substitution Ca + Al = Na + Ti. A detailed petrological investigation of mica schists and blueschists in the immediate vicinity of the serpentinite was undertaken to understand the formation of jadeitite and jadeite-albite rocks in the Tawmaw area. P-T conditions of garnet- and glaucophane-bearing mica schists were calculated using the computer program PTGIBBS (Brandelik and Massonne, 2004) for the thermodynamic calculation of mineral equilibria. In addition, P-T pseudosections, considering the corresponding chemical bulk rock compositions, were calculated with the computer program package PERPLE_X (Connolly, 2005). The obtained results indicate that the P-T condition of metamorphic stage I (e.g. related to the core of garnet in mica schists) were 470-540° C and 16-19 kbar. During stage III (rim composition of garnet, phengite rim) conditions of 5.5-8.5 kbar and 570-630°C were reached. The P-T condition of stage II are intermediate between those of stages I and III. The P-T conditions estimated for glaucophane schists are similar to those of the garnet mica schist. For the core of the garnet, 470-490°C, 18-20 kbar are derived, and the P-T condition of rim compositions of garnet from the glaucophane schist result in 560-620°C, 7-12 kbar. The here derived P-T evolution of the glaucophane schist and garnet mica schist is different to previous interpretions of other authors (Shi et al. 2003, 2001, Goffé et al. 2000). Monazite in garnet mica schists were analysed with the electron microprobe also for their U, Th, and Pb contents. 43 analyses yielded an age range between <15 and 120 Ma.Item Open Access Evolution of rocks from the Münchberg Metamorphic Complex (NE Bavaria)(2017) Waizenhöfer, Florian; Massonne, Hans-Joachim (Prof. Dr.)Die Dissertation „Evolution of Rocks from the Münchberg Metamorphic Complex (NE Bavaria)” behandelt metamorphe Gesteine, hauptsächlich Eklogite und Gneise. Diese Gesteine wurden in einem Gebiet im nordöstlichen (NE) Bayern (Deutschland), der Münchberger Gneismasse (MMC), beprobt. Dort treten variszische Gesteine auf, die Hinweise auf die geodynamische Entwicklung der Plattenkollision von Laurussia und Gondwana in paläozoischer Zeit liefern. Es wurden 14 Gesteinsproben im Detail untersucht.Item Open Access Ashes of oxyfuel- and air-fired pulverised fuel combustion processes - mineralogical characterisation and long-term modification(2010) Schopf, Alexander; Kull, René; Massonne, Hans-Joachim; Theye, ThomasThe focus of our work was the mineralogical analysis of ashes obtained from the combustion of soft brown coal (93.4 % huminite, 4.2 % liptinite, 0.8 % inertinite, 1.6 % pyrite and quartz; detectable amounts of Ca, Fe, Na, K, Mg, Al, Si, S, Cl in the macerals) from the open mine site Welzow-Süd in Lower Lusatia (East Germany). The combustion process was achieved in the Atmospheric Pulverized Fuel Combustion Rig (KSVA) of the Institute of Combustion and Power Plant Technology (IFK), formerly Institute of Process Engineering and Power Plant Technology (IVD) at Universität Stuttgart in air and in the oxyfuel mode. Such ashes, which form during the combustion (oxyfuel process) for power production, were characterised with the methods of polarising microscopy, X-ray diffractometry, electron microprobe analysis and carbon/water-analytics and compared with ashes from the conventional combustion process in air.Item Open Access Zechstein Kupferschiefer at Spremberg and related sites : hot hydrothermal origin of the polymetallic Cu-Ag-Au deposit(2019) Spieth, Volker; Massonne, Hans-Joachim (Prof. Dr.)Copper-silver-gold-polymetallic (Cd, Hg, Mo, Co, Ni, Cr, V, Sb, U, Cs, Re, Pb, Zn, PGE) rich mineralization is present in the deposits containing Kupferschiefer black shale of the lowermost Zechstein Group of Late Permian (Lopingian) age in central Germany and southwestern Poland. Mineralized areas are near large shear lineaments at the border between the Saxo-Thuringian and Rheno-Hercynian zones. Polymetallic mineralization is contained in and geochemically transgresses the Upper Permian Rotliegend strata: the Weissliegend Sandstone, the Zechstein conglomerate, the Kupferschiefer sensu stricto, the Zechstein dolostone, and the overlying Werra carbonate rocks of the Zechstein Group. Hematitic alteration features of the Rote Fäule type are massively present. The mineralization occurs on a continental scale of more than 750 km in an east-westerly direction from eastern Poland to the Rhön near the Rhine valley in Germany in the so called European Copper Belt. The Spremberg-Graustein-Schleife Kupferschiefer deposit in the Lausitz of southeastern Germany has been newly explored and shows the high-grade metallic features of the typical Kupferschiefer deposits, e.g. in the Mansfeld area of Germany and the Lubin area of Poland. The deep drilling campaign from 2008 to 2010 produced much new sample material that became the basis for this scientific research undertaking, which is the first comprehensive study of its type in decades. The major focus of the study was to establish the nature and occurrence of the mineralization in its stratigraphic and ore depositional environment. The methodology employed was: (1) Geological mapping and sampling in the Spremberg-Graustein-Schleife deposit from the new drilling as well as from the drill repository of the LBGR Geological Survey of Brandenburg. This was also done in addition at the Rhön project, the Sangerhausen-Wettelrode deposit in Germany and the Konrad, Lubin, Polkowiecze-Sierosowiecze and Rudna deposits in Poland. (2) The SGS analytical services in Montreal, Canada, geochemically analyzed more than 800 rock powder samples of the exploration campaign 1956 to 1980 at Spremberg, as well as hundreds of new drill core assays were prepared from the new Spremberg exploration campaign. (3) Optical microscopy of more than 1,350 thin and polished rock sections were reviewed and the most important and significant ones were selected for detailed analysis. (4) Electron-microprobe (EMP) analytics, in which chemical compositions of minerals were determined. Textural relations were documented by back-scattered electron images. X-ray maps were produced to recognize the chemical zonation of minerals. 350 polished and thin sections from drill holes and underground locations were selected and analyzed. 626 measurements were taken of stoichiometric and non-stoichiometric metallic minerals, which resulted in new insights about their hot hydrothermal origin and depositional environment. Scanning electron microscope (SEM) studies with wavelength dispersive X-ray spectroscopy microprobe analyses (WDS) were conducted with the CAMECA SX 50. For the calculation of the mineral formulas and the mineral distribution diagrams, the Mincalc-5-program was used. (5) The Raman spectra were measured with the Horiba XpLora Raman microscope with confocal optics with laser wavelengths of 532 and 638 nm. The research focused on minerals and inclusions that were in the size fraction between 1 and 50 nm. Metallic minerals and hydrocarbon aggregates were identified and their intensity frequencies determined. (6) δ34S isotope analysis was conducted on 55 samples that were specifically selected to represent single sulfide aggregates to demonstrate the multi-phase nature of the mineralization. The mineral concentrates were analyzed with an EA-analyzer to SO2 at a reaction temperature of 1,050 °C. The S-isotopic composition was measured with a NC 2500 connected to a Thermo Quest Delta+XL mass spectrometer. The results confirmed the multi-phase nature of the deposit mineralization and supported the new model of origin. (7) Rock samples in historical and significant museum collections were reviewed and evaluated at the following places: Geological Collection at Universität Tübingen, Mansfeld Museum, Wettelrode Röhrigschacht Museum, German Federal Geological Survey Museum at Potsdam, Freiberg Bergakademie Mineralogical Museum, Polish Geological Museum, Warsaw, and Collection of the Mineralogical Institute of University Cracow, Poland. (8) Research progress was presented and discussed in-house and with national and international researchers at seminars, conferences and through publications. The new research results show that the high-grade, Upper Permian, Zechstein polymetallic deposits indicate strong chemical and paragenetic relationships that lead to a unified genetically linked model related to deep-sourced, hot hydrothermal, rift-related volcanism. Mantle heat during failed, intra-continental rifting of the Pangea supercontinent at the end of the Permian time released vast amounts of the exotic metal-rich, alkali-rich, silica-aluminum-rich, organic-rich, halogen-rich, high-density brines into deep-basement fractures, depositing them above the continental flysch Rotliegend sandstones and conglomerates. Detailed investigations show that the high-grade, exotic metal and hydrocarbon mineralization has a hot hydrothermal origin. These result in a micro-layered deposit that was extruded on the Upper Permian Rotliegend peneplain that may have been covered with a shallow Zechstein sea, which was very hostile to lifeforms, at the time of the Permian Mass Extinction. The mineral assemblies are unusual, often chemically non-stoichiometric and unique in their composition as they contain high-temperature and low-temperature minerals adjacent to each other. The stability fields of the sulfides indicate the temperature ranged between 72 °C and 557 °C and up to 1,120 °C for high digenite. Mineralogical results obtained through microscopy, microprobe, Raman spectroscopy, geochemistry and δ34S isotope analysis in this thesis show that: o The Kupferschiefer deposit type mineralization in its vast majority is somewhat monotonous, as it is made up in Spremberg and the European Copper Belt mainly of chalcocite (Cu2S), digenite (Cu1.75S5), covellite (CuS), bornite (Cu5FeS4), and chalcopyrite (CuFeS2), plus a high hydrocarbon content, which is significant as it occurs over a distance of more than 750 km in length. o Many of the copper minerals are of non-stoichiometric composition and unusual association. Bornite, chalcocite, chalcopyrite and pyrite occur as spherules, immiscible metallic drops in the slurry mud. Bornite of the Kupferschiefer sensu stricto T 1 layer often shows exsolutions of electrum (AuAg) and other solid state exsolutions with chalcopyrite and covellite, indicating pre-mixture in the rising metal-hydrocarbon mud slurry and rapid cooling after extrusion on the sea floor surface. o The microprobe element analysis of sulfide phases that are widespread in natural ores of the Kupferschiefer Cu-Ag deposits plot in a phase field that includes chalcocite, digenite, djurleiite, anilite, yarrowite (“blaubleibender” covellite), klockmannite, and krutaite. Klockmannite (CuSe) and krutaite (CuSe2) have a stability field of about 343 °C and 384 °C and thus document the high hydrothermal nature of the mineral deposition. o The δ34S sulfur stable isotopes are a unique feature to the Kupferschiefer sensu stricto and at Spremberg have a similar composition as those of the copper mineralization of the other deposits of the European Copper Belt. The δ34S sulfur stable isotopes are light to very light with values ranging from -31‰ to -40‰ (permille) in chalcocite-digenite and chalcopyrite samples of the lower Kupferschiefer sensu stricto. Given the high temperature of the sulfide mineralization, these low values cannot be explained by microbial reduction. As it is shown in published diagrams, deep-sourced systems of ultramafic to serpentinitic origin and composition can contribute brines with a similar δ34S sulfur stable isotope composition. o Geochemical major and trace element compositions are anomalous and are much enhanced compared to average global black shale. The Kupferschiefer sensu stricto analysis and geostatistical comparison diagrams demonstrate the interdependence of the base, precious and polymetallic mineralization with the hydrocarbon deposition in the Zechstein rocks. o Geometallurgical analysis of the available operational and scientific data proves the genetic association of the enriched ultrabasic-sourced elements PGE, Co, Ni, Cr, V, Se, Re, Os with the contemporaneously deposited hydrocarbons. o Geological observation and mineralogical analyses demonstrate that the hematitic “Rote Fäule” is a post Zechstein Kupferschiefer, pervasive alteration event. In places, the “Rote Fäule” may have two distinct phases, of which one might have added gold to the system, forming independent new deposits. The advancing “Rote Fäule” front creates a “TZ Transition Zone”, where existing base and precious metals are enriched to a higher grade. o The age of the Zechstein Kupferschiefer deposition is considered to be 252.5 M.y. This might vary slightly along the 750 km of the European Copper Belt. The age dating relies on illite and rhenium-osmium ages. Spremberg samples have been submitted to age dating. The mineralization has a multi-phase history with age dates spreading from 267.7 M.y. to the “Rote Fäule” alteration event date of 244.5 M.y. o Large, deep-reaching, continent-size rifting lineaments are known in the Zechstein mineralized area of the European Copper Belt. These NW-SE lineaments are disrupted by NE-SW faults. This tectonic pattern is common in all Kupferschiefer districts and has been demonstrated with a seismic exploration program at Spremberg. Geological observations and mapping in Sangerhausen-Wettelrode, Spremberg and the Lubin-Rudna district show that: o The Weissliegend sand is an injectite/extrudite, silica slurry of Zechstein age that mostly rests on top of the Permian Rotliegend peneplain and is covered in an undulating manner by Kupferschiefer sensu stricto. o The Weissliegend sands are cut by veins and veinlets of sulfides and hydrocarbon and Kupferschiefer-like black mud rock that may represent the feeder veins of an open, hot hydrothermal vent. o The Weissliegend sand hosts by far the majority in quality and quantity of the Kupferschiefer-type deposit mineable copper resources measured in 100s of million of tons. o These observations resulting in a high-temperature, hydrothermal emplacement model lead in their conclusion to a paradigm change that replaces the “obsolete” syn-sedimentary epigenetic model, with consequences: - future exploration and mine development, - can rely on parameters that are congruent with the scientific knowledge that in many aspects resembles Volcanic Submarine Massive Sulfide deposits, and - will assist in the finding and development of the so far termed(by the USGS) “undiscovered Kupferschiefer resources”. • The new model for the Zechstein Kupferschiefer deposits postulates a high-energy, hot-hydrothermal, extrusive environment not dissimilar to submarine “Black Smoker” and volcanogenic, submarine, metal-brine deposits. The metal-rich fluids ascended through deep-reaching faults and erupted as slurries in low-relief, mud volcanism above fractures in an open, shallow, inland sea. Metal sulfide deposition is systematically accompanied by the precipitation of silica, dolomitic carbonate, and illite, as well as primary copper chlorides, such as atacamite (CuCl2) and other brine minerals, such as anhydrite and sylvite. • The ultimate brine source is interpreted to be serpentinized peridotite in the lower crust near the Moho transition to the mantle. Dehydration of the serpentinite source to talc (steatization) by mantle heat during failed, intra-continental rifting of the Pangaea supercontinent at the end of Permian time released vast amounts of element-laden, high-density brines into deep basement fractures, depositing them above the continental flysch sediment Rotliegend sandstone and conglomerate peneplain in the shallow Kupferschiefer sea, which is analogous to the modern northern Caspian Sea and the Salton Sea of southern California, USA.