Die Arbeit befaßt sich mit binären Legierungssystemen, die eine geringe Mischbarkeit der Komponenten im festen Zustand und eine Entmischungstendenz in der Schmelze aufweisen. Die Nahordnung in den binären Legierungsschmelzen Ag-Bi, Bi-Cu und Cu-Pb wird über einen großen Konzentrationsbereich mit Röntgenbeugung untersucht, die Nahordnung und die mittelreichweitige Ordnung in der Ga-Tl-Schmelze hingegen im kritischen Bereich mit Neutronenweitwinkel- und Kleinwinkelbeugung. Ag-Bi und Bi-Cu sind eutektische Systeme mit einem Wendepunkt in der Liquiduslinie, während die Systeme Cu-Pb und Ga-Tl monotektisch sind und eine Mischungslücke im flüssigen Bereich aufweisen. Die Arbeit stellt die verwendeten Beugungsmethoden vor und beschreibt die Röntgendiffraktometrie besonders ausführlich. Die erhaltenen Strukturfaktoren und Paarverteilungsfunktionen werden dargestellt und mit anderen Untersuchungen verglichen. Durch Modellierung werden charakteristische Eigenheiten der Entmischungssysteme wie die Aufspaltung des ersten Maximums, die negativen Faber-Ziman-Strukturfaktoren bei kleinen Q-Werten und die schwache Struktur bei großen Q-Werten qualitativ wiedergegeben. Im Fall der Bi-Cu Schmelze wird durch Kombination von Daten aus Röntgen- und Neutronenbeugung mit Reverse Monte Carlo Simulation ein neuer Satz von partiellen Strukturfaktoren ermittelt, bei dem die partiellen Strukturfaktoren S_{BiCu}(Q) für die Bi-Cu-Wechselwirkung über den gesamten Konzentrationsbereich zuverlässiger sind als zuvor. Mit der Kleinwinkelstreuung werden die Konzentrationsfluktuationen im kristischen Bereich der Ga-Tl-Legierungsschmelze quantitativ beschrieben. / (Short- and medium-range order in the binary liquid alloys : Ag-Bi, Bi-Cu, Cu-Pb, Ga-Tl) The short-range order (SRO) and the medium-range order (MRO) are investigated in binary alloys with a negligible solubility of the components in the solid state and a demixing tendency in the liquid state. Ag-Bi and Bi-Cu are eutectic systems with an inflexion point in the liquidus line; Cu-Pb and Ga-Tl are monotectic with a miscibility gap in the liquid state. The SRO in the Ag-Bi, Bi-Cu and Cu-Pb melts is studied by means of X-ray diffraction over a large concentration range, whereas wide-angle and small-angle neutron scattering are used for investigation of the SRO and MRO of the Ga-Tl melt near the critical concentration. The diffraction methods used in the work are presented. The treatment of the X-ray scattering data is discussed in detail. The obtained Faber-Ziman total structure factors S(Q) and pair correlation functions g(r) are plotted and compared with results from the literature. The peculiarities of S(Q) such as the splitting of the first maximum, the negative Faber-Ziman structure factors in the Q-range near 1 Å^-1, the vanishing structure oscillations for Q-values beyond the first maximum are described qualitatively with a simple demixing model. In the case of the Bi-Cu melt, the contrast between X-Ray and neutron diffraction is used to assess the partial structure factors with Reverse Monte Carlo simulation. It is shown that the MRO of the Ga-Tl melt at the critical concentration is well described with a correlation length in the Ornstein-Zernike theory.

The trend towards a more circular economy presents a unique challenge for the pyrometallurgical engineer. Secondary feeds bring complexity to the smelter in the form of non-traditional chemistries and minor elements. Models of furnaces will play an important role in this paradigm. Models should be able to predict operations in dynamic systems that do not always operate at equilibrium.The development of a top submerged lance (TSL) model was the subject of this study because the TSL has proven to be capable of treating secondary materials.The furnace consists of a vertical cylindrical vessel, containing molten slag and bullion at the bottom. A lance enters through the roof and the tip is submerged in the slag, into which gas and fuel are blown. Secondary or primary feeds, fluxes and reductants can be fed to the furnace. The reactions and interplay between the liquid phases, gas and added reductants set the temperatures and partial oxygen pressures in the furnace. The Connected Local Equilibria (CLE) method was followed to model the furnace. This approach offers the benefit that speciation can be modelled simultaneously for many elements from thermochemical databases. The methodology is to divide the furnace into several equilibrium volumes, based on expected material flows. With each time step, equilibrium in each volume is calculated by Gibbs free energy minimization. Material is then exchanged between volumes according to expected flows. To validate the method, small scale crucible experiments were carried out. Molten lead-containing ferric calcium silicate slags (PbO-FCS slag, also containing GeO2, TeO2 and SnO2 in concentrations ˂ 1 wt%) were reduced under controlled CO/CO2 atmospheres to produce lead bullion. The kinetics of the process were measured. Similar experiments were carried out with a copper-containing ferric calcium silicate system. The CLE method was applied to simulate the data, using HSC Sim software. The crucible was divided into four equilibrium volumes: slag-gas contact; slag; slag-hearth contact; hearth. The gas flowrate to the slag-gas contact was determined by following a rate-law in the form of chemical reaction control (e.g. Rg-s = kapp.pCO (mol O.cm-2.s-1)). By using a single fitting factor (kapp), the dynamic behaviour of lead and the minor elements (tin, tellurium, germanium) could be predicted. The same method was successfully used for the CuO-FCS system. The use of this method enhanced understanding of the experiments, by showing the component speciation during reduction. Full-scale TSL models were then developed using HSC Chemistry software and SimuSage software. In both cases the CLE method was applied. The flow patterns in the furnace were gleaned from published computational fluid dynamics (CFD) work. The interface areas were not known, and assumptions thus needed to be made to model an industrial process for lead-oxide FCS slag reduction. It was shown that the model can provide useful insight into real-world problems. Two branches of modelling might develop from this work. In one, CFD work can quantify interface areas in the furnace, so that CLE models similar to the current work are possible. In the second, only bulk fluid movement might be used. In either case, this work validates the approach of using a thermochemical approach to model kinetics.:1 INTRODUCTION 1.1 THE METALLURGICAL CHALLENGE TO ACHIEVE A CIRCULAR ECONOMY 1.2 APPLICATION OF UNIT MODELS IN TECHNO-ECONOMIC, EXERGY AND ENVIRONMENTAL FOOTPRINT ANALYSES 1.3 FOCUS OF THE CURRENT WORK 2 RESEARCH OBJECTIVES 3 LITERATURE REVIEW 3.1 LEAD METALLURGY (INCLUDING WEEE) 3.2 COPPER METALLURGY 3.3 EQUILIBRIUM BEHAVIOUR OF MINOR ELEMENTS IN LEAD AND COPPER METALLURGY 3.4 SLAG REDUCTION KINETICS 3.5 TSL FURNACE 3.6 MODELLING OF BATH-TYPE SMELTERS 3.6.3 CFD Modelling 4 EXPERIMENTAL METHODOLOGY 4.1 MASTER SLAG PREPARATION 4.2 EXPERIMENTAL SETUP 4.3 REDUCTION EXPERIMENT PROCEDURE 4.4 LIST OF EXPERIMENTS 4.5 ANALYTICAL METHOD 4.6 REACTION OF SLAGS WITH CRUCIBLE WALLS 5 EXPERIMENTAL ERROR EVALUATION 5.1 ERROR IN MASTER SLAG COMPOSITION MEASUREMENTS 5.2 REPEAT TESTS 5.3 EXPERIMENTAL ERROR 6 MODELLING OF KINETICS WITH HSC SIM 6.1 HSC CHEMISTRY DYNAMIC MODULE AND CONNECTED LOCAL EQUILIBRIA MODELLING 6.2 RESULTS FOR MODELLING LEAD EXPERIMENTAL RESULTS WITH HSC CHEMISTRY 6.3 RESULTS FOR MODELLING COPPER EXPERIMENTAL RESULTS WITH HSC CHEMISTRY 7 TSL MODEL IN HSC CHEMISTRY 7.1 FLUID FLOW IN TSL FOR CONNECTED LOCAL EQUILIBRIA MODELLING 7.2 TANKS AND OPERATIONS IN HSC SIM MODEL 7.3 EXAMPLE OF HSC SIM CLE MODEL APPLICATION 8 TSL MODEL ON SIMUSAGE PLATFORM 8.1 METHOD FOR SIMUSAGE MODEL 8.2 SPECIES SELECTION IN SIMUSAGE MODEL 8.3 EXAMPLE OF SIMUSAGE CLE MODEL APPLICATION 9 COMPARISON OF HSC SIM AND SIMUSAGE RESULTS 10 CRITICAL ANALYSIS OF MODEL METHODOLOGY 10.1 MEASUREMENT OF BULK VOLUME COMPOSITIONS 10.2 HEAT TRANSFER IN HSC SIM AND SIMUSAGE MODELS 10.3 USING BULK FLUID FLOWS VS INTERFACE APPROACH 11 CONCLUSIONS 11.1 MOTIVATION 11.2 LABORATORY KINETIC MEASUREMENTS AND MODELLING WITH CLE METHOD 11.3 TSL MODELLING WITH HSC SIM AND SIMUSAGE 12 REFERENCES

Die Arbeit befaßt sich mit binären Legierungssystemen, die eine geringe Mischbarkeit der Komponenten im festen Zustand und eine Entmischungstendenz in der Schmelze aufweisen. Die Nahordnung in den binären Legierungsschmelzen Ag-Bi, Bi-Cu und Cu-Pb wird über einen großen Konzentrationsbereich mit Röntgenbeugung untersucht, die Nahordnung und die mittelreichweitige Ordnung in der Ga-Tl-Schmelze hingegen im kritischen Bereich mit Neutronenweitwinkel- und Kleinwinkelbeugung. Ag-Bi und Bi-Cu sind eutektische Systeme mit einem Wendepunkt in der Liquiduslinie, während die Systeme Cu-Pb und Ga-Tl monotektisch sind und eine Mischungslücke im flüssigen Bereich aufweisen. Die Arbeit stellt die verwendeten Beugungsmethoden vor und beschreibt die Röntgendiffraktometrie besonders ausführlich. Die erhaltenen Strukturfaktoren und Paarverteilungsfunktionen werden dargestellt und mit anderen Untersuchungen verglichen. Durch Modellierung werden charakteristische Eigenheiten der Entmischungssysteme wie die Aufspaltung des ersten Maximums, die negativen Faber-Ziman-Strukturfaktoren bei kleinen Q-Werten und die schwache Struktur bei großen Q-Werten qualitativ wiedergegeben. Im Fall der Bi-Cu Schmelze wird durch Kombination von Daten aus Röntgen- und Neutronenbeugung mit Reverse Monte Carlo Simulation ein neuer Satz von partiellen Strukturfaktoren ermittelt, bei dem die partiellen Strukturfaktoren S_{BiCu}(Q) für die Bi-Cu-Wechselwirkung über den gesamten Konzentrationsbereich zuverlässiger sind als zuvor. Mit der Kleinwinkelstreuung werden die Konzentrationsfluktuationen im kristischen Bereich der Ga-Tl-Legierungsschmelze quantitativ beschrieben. / (Short- and medium-range order in the binary liquid alloys : Ag-Bi, Bi-Cu, Cu-Pb, Ga-Tl) The short-range order (SRO) and the medium-range order (MRO) are investigated in binary alloys with a negligible solubility of the components in the solid state and a demixing tendency in the liquid state. Ag-Bi and Bi-Cu are eutectic systems with an inflexion point in the liquidus line; Cu-Pb and Ga-Tl are monotectic with a miscibility gap in the liquid state. The SRO in the Ag-Bi, Bi-Cu and Cu-Pb melts is studied by means of X-ray diffraction over a large concentration range, whereas wide-angle and small-angle neutron scattering are used for investigation of the SRO and MRO of the Ga-Tl melt near the critical concentration. The diffraction methods used in the work are presented. The treatment of the X-ray scattering data is discussed in detail. The obtained Faber-Ziman total structure factors S(Q) and pair correlation functions g(r) are plotted and compared with results from the literature. The peculiarities of S(Q) such as the splitting of the first maximum, the negative Faber-Ziman structure factors in the Q-range near 1 Å^-1, the vanishing structure oscillations for Q-values beyond the first maximum are described qualitatively with a simple demixing model. In the case of the Bi-Cu melt, the contrast between X-Ray and neutron diffraction is used to assess the partial structure factors with Reverse Monte Carlo simulation. It is shown that the MRO of the Ga-Tl melt at the critical concentration is well described with a correlation length in the Ornstein-Zernike theory.