The present work is to study slag phenomena in steelmaking process. In order to attain thegoal, a number of high temperature experiments and simulation experiments were carried out. Four master slags were used to study the effect of CaF2 on slag viscosity. Experimentalresults indicated the effect of CaF2 on slag viscosity depended strongly on the composition ofmaster slag. For high basicity slags, CaF2 mainly suppressed the precipitation of solid phasesat lower temperatures, leading to a lower viscosity compared to CaF2-free slags. For slagswith higher SiO2 contents, CaF2 both lowered the viscosity of the liquid phase and suppressedthe precipitation of solid phases. The viscosities of solid-liquid mixtures were experimentally determined for silicon oilparaffinsystem at room temperature and solid-liquid oxide mixture at steelmakingtemperature. The results of both measurements indicated that the increasing trend of mixturesviscosity with particle fraction can be described by Einstein-Roscoe equation.Silicone oils of different viscosities were used to simulate slag foaming. The experimentalresults showed, at a constant viscosity, the foaming height increased first with superficialvelocity before reaching a maximum value. Thereafter, the foaming height decreased with thefurther increase of the superficial velocity. Similar, a maximum foaming height was observedat an optimum viscosity when a constant superficial gas velocity was applied. Based on theexperimental data, a semi-empirical equation of foaming height was developed. Thepredictions of the model agreed well with experiment data. The model could also reasonablywell explain the industrial pilot trial experiments. Water-silicon oils model and liquid alloy (Ga-In-Sn)- 12% HCl acid model were employed tosimulate the formation of open-eyes in a gas stirred ladle. The experimental results indicatedthat the viscosity of the top liquid and the interfacial tension between the two liquids had onlylittle effect on the open-eye size. A semi-empirical model was developed to describe the sizeof open-eye as functions of the gas flow rate, bath height and slag height. The two sets ofparameters obtained for the water and Ga-In-Sn models were very different. Industrial trialswere also conducted to examine the applicability of the models. Liquid alloy model couldwell predict the formation of an open-eye during ladle treatment. Two cold models, sodium tungstate-oil model and water-oil model, were carried out tosimulate the formation of droplets in a gas stirred ladle. The experimental results showed thatthe gas flow rate and interfacial tension had strong impact on the size of droplets. A semiempiricalmodel was developed to describe the size of droplets for water model. Meanwhile,the parameter obtained for water model can be used for sodium tungstate-silicone oil system.The results indicate the model has strong compatibility. / QC 20110419

By analyzing process samples full and pilot scale gasifiers, the main influences affecting their slag are identified. Based on this knowledge as well as the current literature, the effect of crystallization was identified as crucial for understanding slag behavior and is analyzed during cooldown. Finally, the emerging interest in sewage sludge upcycling via gasification necessitated an investigation on the influence of adding P2O5 as slag constituent. All conclusions concerning the full scale gasifier slags were based on XRF, XRD, and SEM-EDX analyses coupled with thermodynamic equilibrium calculations via FactSage. The subsequently presented research on crystallization and the effect of P2O5 was centered on conducting slag viscosity measurements, recreating the conditions of said measurement in a quench oven, and analyzing the resulting quench samples via the mentioned analysis methods. Special focus was put on the phase evolution, its governing factors, and the effect on slag viscosity.:1. INTRODUCTION 1 2. FUNDAMENTALS IN SLAG BEHAVIOR CHARACTERIZATION 3 2.1. BASE TO ACID RATIO AS KEY FIGURE FOR SLAG CHARACTERIZATION 7 2.2. VISCOSITY ALTERING SECONDARY PHASES IN SLAGS 9 2.2.1. The effect of crystallization on slag flow 10 2.2.2. Modelling and measuring crystallization in slags 11 2.3. CRITICAL VISCOSITY 13 2.4. PHOSPHOROUS OXIDE IN SLAGS 15 2.4.1. Behavior of P2O5 within slags 16 2.4.2. Phase separation in melts containing P2O5 17 2.4.3. Effect on slag viscosity 22 3. ANALYTICAL METHODS 26 3.1. SAMPLE PRETREATMENT 26 3.2. ASH FUSION TEMPERATURE 28 3.3. X-RAY FLUORESCENCE MEASUREMENT (XRF) 30 3.4. X-RAY DIFFRACTION 31 3.5. VISCOSITY MEASUREMENT 32 3.6. DIFFERENTIAL THERMAL ANALYSIS (DTA) 36 3.7. QUENCH APPARATUS 37 3.8. SEM-EDX 39 3.9. THERMODYNAMIC EQUILIBRIUM CALCULATIONS 40 4. CHARACTERIZATION OF SLAGS FROM FULL OR PILOT SCALE GASIFIERS 42 4.1. SLAG FROM GENERAL ELECTRICS GASIFIER IN TAMPA 43 4.1.1. Analysis of the suspending main phase 45 4.1.2. Analysis of the silica phase 50 4.1.3. Analysis of the metal enclosures 51 4.1.4. Analysis of the vanadium-rich particles 53 4.1.5. Summary of the analysis of the General Electrics gasifier slag 55 4.2. SLAG FROM GSP GASIFIER 57 4.2.1. NCPP slag 57 4.2.2. Huainan Anhui slag 64 4.2.3. Genesee slag 70 4.2.4. Hambach-Garzweiler 50:50 slag 75 4.2.5. Summary of the analysis of the GSP slags 86 4.3. SLAG FROM BRITISH GAS/LURGI (BGL) GASIFIER 88 4.3.1. Summary and conclusions of the analysis of the BGL slag 99 5. CHARACTERIZING CRYSTALLIZATION DURING SLAG VISCOSITY MEASUREMENTS 102 5.1. EXPERIMENTAL PROCEDURE 103 5.1.1. Sample preparation 107 5.1.2. Viscosity measurement 108 5.1.3. Differential thermal analysis (DTA) 108 5.1.4. Quench oven 108 5.1.5. XRD, XRF, SEM-EDX, and FactSage calculations 109 5.2. RESULTS AND DISCUSSION 109 5.2.1. Slag 1 (CO/CO2 atmosphere) 110 5.2.2. Slag 2 (CO/CO2 atmosphere) 112 5.2.3. Slag 3 (air atmosphere) 116 5.2.4. Slag 3 (CO/CO2 atmosphere) 119 5.3. CONCLUSION AND SUMMARY OF THE STUDY OF CRYSTALLIZATION IN SLAGS DURING COOLDOWN 122 6. THE EFFECT OF PHOSPHOROUS OXIDE ON SLAGS 125 6.1. PRELIMINARY SEWAGE SLUDGE SLAG INVESTIGATION 126 6.1.1. Conclusion and summary sewage slag investigation 136 6.2. EXPERIMENTAL PROCEDURE FOR PARAMETRIC STUDY 139 6.3. PARAMETRIC STUDY 141 6.3.1. HKN with 15% sand (HKNS) 142 6.3.2. HKNS with low P2O5 addition (HKNS5P) 147 6.3.3. HKNS with medium low P2O5 addition (HKNS10P) 153 6.3.4. HKNS with medium high P2O5 addition (HKNS15P) 158 6.3.5. HKNS with high P2O5 addition (HKNS20P) 163 6.3.6. P2O5 distribution 169 6.3.7. Effect of P2O5 on viscosity 174 6.4. SUMMARY ON THE INVESTIGATION OF P2O5 IN SLAGS 179 7. CONCLUSION AND OUTLOOK 185 8. REFERENCES 190 9. APPENDIX A: DIFFERENCE IN PREDICTION OF SEWAGE SLUDGE ELEMENTAL DISTRIBUTION 213 10. APPENDIX B COMPARISON OF XRF ANALYSES OF HKNS-P2O5 MIXTURES 215 11. APPENDIX C EDX MAPS OF THE QUENCH SAMPLES IN THE PARAMETRIC PHOSPHORUS ADDITION STUDY 218 12. APPENDIX D SUMMARY OF PHASE COMPOSITION OF THE EDX MAPS 239 13. APPENDIX E ENRICHMENT FACTORS FOR THE QUENCH SAMPLES IN THE PARAMETRIC PHOSPHORUS ADDITION STUDY 242

The viscosities of a set of silicone oils containing different size ranges of charcoal or paraffin particles as well as the viscosities of silicone oil foams were measured at room temperature in order to determine the effect of dispersed phase on the viscosity of a liquid and its effect on foaming ability. The effective viscosity of the samples increased with volume fraction of the second phase. The foaming ability was improved by the presence of the particles. The improved foaming effect was for the most part not a result of the increased viscosity. No connection between the particle size and the effective viscosity could be determined. On the other hand particle morphology and the particle size distribution had effect on the effective viscosity. The viscosity data were compared with a number of existing equations for the estimation of effective viscosity. Einstein-Roscoe equation is suitable for two-phase mixtures containing globular particles with narrow particle size distribution and low interfacial tension. New mathematical models are required for effective viscosity prediction, where the suspending phase viscosity, effect of the interfacial tension, as well as the particle morphology should be taken in consideration.