Gekürzte Diss. Univ. Bern, 1980. / Titel der Diss.: Mineralogisch-petrographische Untersuchungen in den Erzvorkommen von Affeier und ihrer Umgebung im Verrucano von Ilanz-Obersaxen/Graubünden.

Lignite is still one of the most important energy sources in Germany. In 2017, \SI{24.4}{\percent} of the net electricity production was generated by lignite-fired power plants. The operation of lignite-fired boilers faces challenges such as emission control and slagging and fouling issues. Slagging and fouling issues are caused by inorganic constituents in the coal, also referred to as mineral matter. Mineral matter can be associated with the coal in three different ways: A mineral grain within the coal matrix is referred to as included. A mineral grain that is not asscociated with the organic material is referred to as excluded. In addition, there are inorganic elements that are organically associated with the coal matrix. Due to the reaction front in a burning char particle included particles experience temperatures that can be much higher than what excluded particles experience. Included mineral matter particles also have the potential to coalesce or to react with organically bound elements to form new mineral species Two methods were identified to determine the included and excluded mineral matter in a given coal sample: Float-and-sink analysis and computer controlled scanning electron microscopy (CCSEM). The float-and-sink analysis uses the differences in density between minerals and coal to separate excluded mineral particles from coal particles. CCSEM is an automated SEM-EDS process that allows to analyze a large number of coal particles in a given sample. The SEM uses image analysis to identify coal and mineral particles and to determine the mineral association. Both methods are applied to seven coal samples from three major lignite mining areas in Germany. The results show that in the investgated coals the excluded mineral matter fraction consists mainly of quartz, pyrite/marcasite, clay and gypsum, whereas the included mineral matter fraction is dominated by Ca-S rich minerals. The tendency of slagging and fouling is predicted for all coals on the basis of included and excluded mineral matter. Conventional slagging and fouling indices are applied to the bulk ash composition of the included and excluded fraction determined by float-and-sink analysis. In addition, the composition of individual mineral grains determined by CCSEM-analysis is considered. The slagging indices show significant differences between the included and excluded mineral matter, whereas the fouling indices are in the same range for both fractions. The liquid-to-ash ratio is determined for all coal samples with thermochemical equilibrium calculations. The different temperatures for included and excluded mineral matter are taken into account. All investigated coals show significant liquid-to-ash ratios in both included and excluded fractions. Combustion experiments were conducted with all seven coals at a laboratory-scale test rig for pulverized fuels at TU Dresden and/or at large-scale utility boilers. Ash particle samples collected with the particle-wire-mesh method show particles with mixed-phase composition. These particles are the result of coalescence of included mineral particles or the result of reactions between included mineral grains and organically associated elements. / Mineralische Bestandteile im Brennstoff sind mitverantwortlich für Verschmutzung- und Ver\-schlack\-ungsvorgänge in mit Braunkohle gefeuerten Kraftwerken. Sie werden durch den Verbrennungsprozess freigesetzt und können sich je nach Eigenschaft der Mineralien an verschiedenen Stellen eines Feuerungsprozesses ablagern. Es wird zwischen mit dem Kohlekorn verwachsenen (internen) mineralischen Partikeln und als eigenständige Partikel vorliegenden (externen) mineralischen Partikeln unterschieden. Weiterhin können anorganische Elemente organisch an die Kohlematrix gebunden sein. Mit der Kohlestruktur verwachsene, interne Partikel sind der Reaktionsfront des brennenden Kohlepartikels direkt ausgesetzt. Sie erfahren höhere Temperaturen als externe Partikel. Höhere Temperaturen fördern das Aufschmelzen der Partikel und beeinflussen so das Ablagerungspotential. Mehrere im Kohlekorn vorliegende mineralische Partikel können beim Abbrennen des Restkokses zu einem Partikel mit neuer chemischer Zusammensetzung verschmelzen. Auch Reaktionen mit den organisch gebundenen mineralischen Elementen sind möglich. Es gibt verschiedene Methoden zur Bestimmung der Bindungsart der Mineralien in der Kohle. Die Schwimm- und Sinkanalyse nutzt die unterschiedlich großen Dichten von externen mineralischen Partikeln, Kohlekörnern mit mineralischen Einschlüssen und reinen Kohlekörnern zur Trennung in einzelne Fraktionen. Eine weitere Methode ist die computergesteuerte Rasterelektronenmikroskopie (CCSEM), mit der die Verteilung mineralischer Partikel im Kohlekorn sowie deren Zusammensetzung bestimmt werden kann. Im Rahmen dieser Dissertation werden beide Methoden auf sieben Kohleproben aus den drei größten deutschen Braunkohleabbaugebieten angewendet. Die Anwendung der Schwimm- und Sinkanalyse und von CCSEM auf die ausgewählten Kohleproben zeigen, dass die externen mineralischen Partikel in den untersuchten deutschen Braunkohlen von Quarz dominiert werden. Weitere signifikante Bestandteile sind Pyrit/Markasit, Tone und Gips. Die internen Minerale werden von Ca-S-haltigen Mineralien dominiert. Das Verschmutzungs- und Verschlackungspotential der untersuchten Kohlen wird u.a. mit Hilfe von Kennzahlen bewertet. Die Kennzahlen zur Bewertung des Verschlackungspotentials zeigten deutliche Unterschiede zwischen der internen und externen mineralischen Fraktion. Die Verschmutzungskennzahlen liegen in ähnlichen Größenordnungen für beide Fraktionen. Ein weiteres Bewertungskriterium ist der Flüssigphasenanteil bei der maximalen Partikeltemperatur. Dieser wird auf der Basis des thermochemischen Gleichgewichts berechnet. Dabei wird berücksichtigt, dass interne und externe mineralische Partikel unterschiedliche maximale Temperaturen erfahren. Sowohl der interne mineralische Anteil, als auch der externen Anteil aller untersuchten Kohlen zeigt signifikante Flüssigphasenanteile. Mit allen in der Arbeit untersuchten Kohlen wurden Verbrennungsexperimente in einer Technikumsanlage zur Verbrennung staubförmiger Brennstoffe sowie in Großkraftwerken durchgeführt. Mit der Methode der Partikelgitternetzsonde gesammelte Aschepartikelproben zeigen, dass beim Verbrennungsvorgang Partikel mit einer Mischphasenzusammensetzung entstehen. Diese Partikel sind durch das Verschmelzen verschiedener interner Mineralien bzw. aufgrund von Reaktionen von internen Mineralien mit organisch gebundenen anorganischen Elementen entstanden.

In der Achatstraße 1 in 09356 St. Egidien ist seit 1998 die Ausstellung 'Achatsammlung und Lagerstättenkabinett St. Egidien' in den Räumen des ehemaligen VEB Nickelhütte St. Egidien beheimatet. In der Ausstellung wird die historische Entwicklung der Nickelhütte St. Egidiens dargestellt. Es wird der Prozess des Abbaus der Nickelerze über die Verhüttungsprozesse bis hin zu den Endprodukten aufgezeigt. Während den bergbaulichen Auffahrungen der Serpentinit-Tagebaue zur Nickelhydrosilikatgewinnung traten vielfältige Vererzungen zutage. Ein auf der Welt einzigartiges Vorkommen von Krokoitmineralisationen wurde angetroffen und dokumentiert. Zudem wurden speziell im nordwestlichen Bereich des VEB Nickelhütte St. Egidien große Mengen hervorragender Achate und Jaspise gefunden, die in ihrer Vielfalt und Gestalt einzigartig und somit weltweit erkennbar sind. Die Dokumentation enthält den Stand vom Januar 2012. Zu diesem Zeitpunkt umfasste der Bestand 309 Achate. Dazu kamen 242 Exponate der Krokoitmineralisationen aus dem Tagebau Callenberg Nord I sowie Nickelerzmineralisationen der Tagebaue Callenberg Süd I, Süd II sowie Callenberg Nord I und Nord II. Die Tagebaue sind renaturiert und bereichsweise verfüllt. Der VEB Nickelhütte St. Egidien wurde teilweise zurückgebaut und wird heute für andere Zwecke genutzt. Nachfolgegesellschaft ist die Industriegesellschaft St. Egidien mbH i. L. in der Achatstraße 1, 09356 St. Egidien.:1. Veranlassung 2. Fotokataloge 2.1 Achate 2.2 Mineralisationen der Nickelerzlagerstätten 2.3 Mineralisationen des Krokoitvorkommens Callenberg 3. Tabellarische Auflistung der Mineralien und Gesteine 3.1 Bestandsaufnahme Vitrinen Nickelerzabbau, Stand: 12.03.2011 3.2 Bestandsaufnahme Vitrinen Mineralienverein Leonhardt, Stand: 12.10.2010 Danksagung

The concomitant occurrence and reported discrepant behavior of uranium and arsenic in water bodies is a major health and environmental concern. This study combined batch and column experiments, hydrogeochemical simulations and XAFS spectroscopy to uncover the exchange mechanisms governing uranium fate between water and scrap metallic iron, minerals and Shewanella putrefaciens surfaces in the presence of arsenic. The main results suggest that both water chemistry and the solid phase composition influence uranium fate in the presence of arsenic. The importance of uranyl-arsenate species as a major control of uranium behavior in the presence of arsenic is shown. The toxicity of arsenic and the presence of nitrate are interpreted as limiting factors of the enzymatic reduction of both toxins. Besides, XANES fingerprinting and EXAFS modeling have confirmed precipitation/co-precipitation of uranyl-arsenates as a major mechanism controlling uranium behavior in the presence of arsenic.

The concomitant occurrence and reported discrepant behavior of uranium and arsenic in water bodies is a major health and environmental concern. This study combined batch and column experiments, hydrogeochemical simulations and XAFS spectroscopy to uncover the exchange mechanisms governing uranium fate between water and scrap metallic iron, minerals and Shewanella putrefaciens surfaces in the presence of arsenic. The main results suggest that both water chemistry and the solid phase composition influence uranium fate in the presence of arsenic. The importance of uranyl-arsenate species as a major control of uranium behavior in the presence of arsenic is shown. The toxicity of arsenic and the presence of nitrate are interpreted as limiting factors of the enzymatic reduction of both toxins. Besides, XANES fingerprinting and EXAFS modeling have confirmed precipitation/co-precipitation of uranyl-arsenates as a major mechanism controlling uranium behavior in the presence of arsenic.

Slags plays a significant role at high temperature processes. The estimation of the slag viscosity is vital for the safe run of e.g. entrained flow gasifiers. One opportunity of determination is rotational viscometry. This technique is disadvantageous in view of elevated temperatures, applied materials and the necessary time. Additionally, the viscosity can be predicted by the help of viscosity models, where viscosity is a function of slag composition and temperature. Due to changing slag properties within the technical processes, the calculated viscosities can hugely differ from measured ones. In this work, the viscosities of 42 slags where measured up to 100 Pa s and temperatures up to 1700 °C. Oxidizing and reducing conditions were applied. Additionally, selected slag samples were quenched at defined temperatures to qualitatively and quantitatively determine the formed minerals by X-ray diffraction (XRD). Differential temperature analysis (DTA) was applied to find the onset of crystallization for the complementation of investigations. The Einstein-Roscoe equation was chosen to improve the classic viscosity models. Reducing atmosphere decreased viscosity and the number of formed minerals was increased. Slags show a shear-thinning behavior above ca. 10 vol.-% of solid mineral matter. Also, Newtonian behavior was observed up to 60 vol.-%. To overcome problems with the kinetic cooling behavior of the slags, a viscosity approximation method was applied afterwards. This can result in optimized viscosity predictions when several preconditions are fulfilled.

Slags plays a significant role at high temperature processes. The estimation of the slag viscosity is vital for the safe run of e.g. entrained flow gasifiers. One opportunity of determination is rotational viscometry. This technique is disadvantageous in view of elevated temperatures, applied materials and the necessary time. Additionally, the viscosity can be predicted by the help of viscosity models, where viscosity is a function of slag composition and temperature. Due to changing slag properties within the technical processes, the calculated viscosities can hugely differ from measured ones. In this work, the viscosities of 42 slags where measured up to 100 Pa s and temperatures up to 1700 °C. Oxidizing and reducing conditions were applied. Additionally, selected slag samples were quenched at defined temperatures to qualitatively and quantitatively determine the formed minerals by X-ray diffraction (XRD). Differential temperature analysis (DTA) was applied to find the onset of crystallization for the complementation of investigations. The Einstein-Roscoe equation was chosen to improve the classic viscosity models. Reducing atmosphere decreased viscosity and the number of formed minerals was increased. Slags show a shear-thinning behavior above ca. 10 vol.-% of solid mineral matter. Also, Newtonian behavior was observed up to 60 vol.-%. To overcome problems with the kinetic cooling behavior of the slags, a viscosity approximation method was applied afterwards. This can result in optimized viscosity predictions when several preconditions are fulfilled.:List of Tables ............................................................................................................ vi List of Figures ........................................................................................................ viii Symbols and Abbreviations .................................................................................. xviii 1. Introduction and Aim ....................................................................................... 1 2. General Overview of Slag ............................................................................... 2 2.1 Viscosity ...................................................................................................... 2 2.1.1 Viscosity Introduction ........................................................................... 2 2.1.2 Flow behavior of fluids ......................................................................... 3 2.2 Slag Definition and Phase Diagrams ........................................................... 4 2.3 Solid Slag Structure .................................................................................... 5 2.4 Liquid Slag Structure ................................................................................. 10 2.5 Basicity and B/A-ratio ................................................................................ 11 2.6 Slag Components...................................................................................... 13 2.6.1 Silicon dioxide .................................................................................... 13 2.6.2 Aluminum oxide ................................................................................. 13 2.6.3 Calcium oxide .................................................................................... 15 2.6.4 Iron oxide ........................................................................................... 16 2.6.5 Magnesium Oxide .............................................................................. 18 2.6.6 Potassium Oxide ................................................................................ 19 2.6.7 Sodium Oxide .................................................................................... 20 2.6.8 Titanium Oxide ................................................................................... 21 2.6.9 Phosphorous ...................................................................................... 22 2.6.10 Sulfur .............................................................................................. 22 2.7 Summary of Last Chapters ........................................................................ 23 3. Slag Viscosity Toolbox .................................................................................. 25 3.1 Slag Viscosity Predictor............................................................................. 25 3.2 Slag Viscosity Database............................................................................ 26 3.3 Prediction Quality of Viscosity Models ....................................................... 27 4. Classic Slag Viscosity Modelling ................................................................... 30 4.1 Selected Classic Viscosity Models ............................................................ 31 4.1.1 S2 ....................................................................................................... 32 4.1.2 Watt-Fereday ..................................................................................... 32 4.1.3 Bomkamp ........................................................................................... 32 4.1.4 Shaw .................................................................................................. 32 4.1.5 Lakatos .............................................................................................. 33 4.1.6 Urbain ................................................................................................ 33 4.1.7 Riboud ............................................................................................... 33 4.1.8 Streeter .............................................................................................. 34 4.1.9 Kalmanovitch-Frank ........................................................................... 34 4.1.10 BBHLW .......................................................................................... 34 4.1.11 Duchesne ....................................................................................... 34 4.1.12 ANNliq ............................................................................................ 35 4.2 Need of Improvement in Viscosity Literature ............................................. 35 4.3 Summary of Last Chapters ........................................................................ 36 5. Advanced Slag Viscosity Modelling .............................................................. 37 5.1 Crystallization ............................................................................................ 37 5.1.1 Nucleation .......................................................................................... 38 5.1.2 Crystallization Rate ............................................................................ 39 5.1.3 Crystallization Measurement Methods ............................................... 39 5.2 Slag Properties Changes During Crystallization ........................................ 40 5.2.1 Slag Density ....................................................................................... 40 5.2.2 Solid Volume Fraction ........................................................................ 46 5.2.3 Estimation of Slag Composition During Cooling ................................. 46 5.3 Viscosity Depending on Particles and Shear Rate..................................... 47 5.3.1 Einstein-Roscoe Equation .................................................................. 48 5.3.2 Improved Modelling Approach by Modified Einstein-Roscoe .............. 49 5.4 Summary of Last Chapters ........................................................................ 50 6. Experimental Procedures ............................................................................. 52 6.1 Viscosity Measurements ........................................................................... 52 6.1.1 Estimating Parameter Ranges of Viscosity Measurements ................ 53 6.1.2 Viscosity Measurement Procedure ..................................................... 54 6.2 Thermal Analysis of Slags ......................................................................... 55 6.2.1 Experimental Conditions of DTA ........................................................ 55 6.3 Phase Determination ................................................................................. 55 6.3.1 Quench Experiment Processing ......................................................... 56 6.3.2 Phase Determination on XRD Results ............................................... 56 6.4 Summary of Last Chapters ........................................................................ 57 7. Results and Discussion ................................................................................ 58 7.1 Selected Slag Samples ............................................................................. 58 7.1.1 Slag Sample Composition Before Viscosity Measurements ............... 58 7.1.2 Slag Sample Composition After Viscosity Measurements .................. 59 7.2 General Results of Viscosity Measurements ............................................. 60 7.2.1 Viscosity under Air Atmosphere ......................................................... 63 7.2.2 Viscosity under Reducing Atmospheres ............................................. 65 7.2.3 Viscosity under Constant Partial Oxygen Pressure ............................ 66 7.2.4 Summary of Last Chapter .................................................................. 68 7.3 Mineral Formation ..................................................................................... 69 7.3.1 General Results on Primarily Mineral Formation ................................ 69 7.3.2 Influences on Primarily Mineral Formation ......................................... 70 7.3.3 Mineral Formation over Wide Temperature Ranges ........................... 71 7.3.4 Summary of Last Chapter .................................................................. 77 7.4 Results Obtained by DTA .......................................................................... 78 7.4.1 Comparing Results obtained by DTA and Quenching ........................ 80 7.4.2 Summary of Last Chapter .................................................................. 82 7.5 Shear Rate Influence on Slag Viscosity ..................................................... 82 7.5.1 Shear Rate Influence under Oxidizing Atmospheres .......................... 83 7.5.2 Shear Rate Influence under Reducing Atmospheres .......................... 87 7.5.3 Shear Rate Influence under Constant Atmospheres .......................... 91 7.5.4 Summary of chapter ........................................................................... 92 7.6 Atmospheric Influence on Viscosity ........................................................... 93 7.6.1 Summary of Last Chapter .................................................................. 95 7.7 Cooling Rate Influence on Slag Viscosity .................................................. 95 7.7.1 Summary of Last Chapter .................................................................. 97 8. Advanced Viscosity Modelling Approach ...................................................... 99 8.1 Prediction Quality of Classical Viscosity Models ........................................ 99 8.1.1 Selecting the Best Viscosity Model for Newtonian Flow ..................... 99 8.1.2 Summary of Last Chapter ................................................................ 103 8.2 Predicting Liquidus Temperature ............................................................. 103 8.2.1 Comparing Liquidus Calculations and Quenching Experiments ....... 103 8.2.2 Comparing DTA Results and Liquidus Calculations ......................... 105 8.2.3 Summary of Last Chapter ................................................................ 107 8.3 Predicting Liquid Slag Composition ......................................................... 108 8.3.1 Results of Slag Composition Calculations at Oxidizing Conditions ... 108 8.3.2 Results of Slag Composition Calculations at Reducing Conditions ... 110 8.3.3 Summary of Last Chapter ................................................................ 111 8.4 Modelling Approach ................................................................................ 112 8.4.1 Development of Datasets for Advanced Viscosity Modeling ............. 113 8.4.2 Summary of Last Chapter ................................................................ 116 8.5 Results of Advanced Slag Viscosity Modelling Approach ........................ 116 8.5.1 Summary of Last Chapter ................................................................ 121 9. Summary .................................................................................................... 123 10. Appendix: Information on Classic Viscosity Modelling ................................. 126 10.1 Backgrounds of Applied Viscosity Models............................................ 126 10.2 Viscosity Model of the BCURA (S2) ..................................................... 129 10.3 Watt-Fereday ....................................................................................... 130 10.4 Bomkamp ............................................................................................ 130 10.5 Shaw ................................................................................................... 131 10.6 Lakatos Model ..................................................................................... 132 10.7 Urbain Model ....................................................................................... 133 10.8 Riboud Model ...................................................................................... 134 10.9 Streeter Model ..................................................................................... 136 10.10 Kalmanovitch-Frank Model .................................................................. 137 10.11 BBHLW Model ..................................................................................... 137 10.12 Duchesne Model .................................................................................. 139 10.13 ANNliq Model ...................................................................................... 141 11. Appendix: Settings of Equilibrium Calculations ........................................... 143 12. Appendix: Parameters of Einstein-Roscoe Equation ................................... 153 13. Appendix: Ash and Slag Sample Preparation ............................................. 155 14. Appendix: Experimental Procedures: Viscometer ....................................... 159 14.1 General Viscometer Description .......................................................... 159 14.2 Temperature Calibration ...................................................................... 160 14.3 Viscometer Calibration ......................................................................... 160 14.4 Accuracy and Reproducibility of HT-Viscosity Measurements .............. 161 14.5 Influence of Inductive Heating .............................................................. 163 14.6 Influence of Measurement System Materials ....................................... 164 15. Appendix: Experimental Procedures: Quenching Furnace .......................... 167 16. Appendix: Slag Sample Parameters and Composition ................................ 168 17. Appendix: Slag Viscosity Measurements Results ....................................... 175 18. Appendix: Viscosities at Different Cooling Rates ........................................ 182 19. Appendix: Slag Viscosity Modelling: AALE Calculations ............................. 187 20. Appendix: Advanced Viscosity Modelling: a-factors .................................... 193 21. Appendix: Slag Mineral Phase Investigations and Modelling ...................... 197 22. Appendix: Results of DTA Measurements on Slags .................................... 207 23. Appendix: Advanced Slag Viscosity Modelling Approach ............................ 211 References ........................................................................................................... 228