Resilience has been gaining importance as a key element that prepares the supply chains to respond after disruptions. In this thesis, the material supply chain resilience framework is used to study the supply chain of tin before and during the disruption caused by the COVID-19 pandemic. Tin is a small-scale market compared to other major metals but its importance is increasing thanks to its possible applications in the next-generation lithium-ion batteries, fundamental for the energy transition. Besides, Tin is one of the main elements used in the semiconductor industry which is at the centre of the trade war between the US and China. In order to increase its potential and be used in “next-gen” batteries, tin supply chains must show resilience. Using qualitative and quantitative data and modelling, this paper aimed to explore the resilience of the supply chain of tin. The research showed that Tin demonstrated considerable resilience during the COVID-19 disruptions ,thanks to the semiconductors and Chinese demand, both of which increased during the second quarter of 2020. Currently, almost half of tin production goes to solders, which explains the high dependency between the tin market and the semiconductor market. China is the biggest producer and consumer of tin, which makes the demand for tin dependent on Chinese demand. The analysis of the resilience mechanisms showed stockpiling and diversity of supply are integrated into the supply chain but their contribution to resilience remain low. Substitution could not be considered a resilience mechanism due to the lack of substitutes for tin solders. The resilience mechanisms would gain importance in the future of tin if it would be used in new technologies. The model presented in this thesis estimates the amount of tin that will be used by 2030. With this in mind, recycling of tin must be increased to support the future demand. Consequently, Governments and companies must invest in technologies in order to increase the recycling of E-waste. Lastly, the development of the relations between the US and China will also interest the tin supply chain. In this regard, three different sub scenarios are analysed: complete decoupling, partial decoupling, and no-decoupling.
 
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The transition to a renewable electricity system requires more intensive material use, causing problem shifting in environmental impacts. To conserve resources for the future and mitigate environmental impact, circular economy principles are needed. This study analyses material flows in Dutch wind energy towards 2050 to identify the potential for material recovery. This reveals material demand, stock, secondary material supply and required recycling infrastructure within environmental and economic context. Material compositions, current stock and future installed capacity result in inflow, stock and outflow of materials in Dutch wind energy. Inflows or demand for materials is increasing rapidly due to strong expected growth in the near future (2023), additional inflows are required after 2030 for stock maintenance. Outflows fluctuate, partly due to an early peak in onshore decommissioning and late peak in offshore decommissioning caused by a more mature stock of onshore wind turbines and currently developing stock of offshore wind turbines. The outflow of scrap materials is used to determine secondary materials through various recycling routes. For steel, iron, aluminium and copper minor processing losses occur as materials oxidize or get lost to slag. Due to partial removal of monopiles, a hibernating stock is expected for structural steel that increases towards 0.5 Mt in 2050. Current steel and iron recycling results in dilution and therefore loss of function of valuable and critical alloying elements. Composite waste management in wind energy is a major challenge as closed-loop recycling of composites is not feasible. The cascading effect of material quality results in low-value materials, with varying potential demand. Repurposing of blade segments requires minimal processing and could be implemented at present, provided that there is enough demand for composite sheet and beam segments. Cement co-processing uses existing cement production infrastructure and could be implemented at present, with ample demand for cement clinker. Dutch wind energy could exclusively provide sufficient composite scrap material to run industrial-scale mechanical grinding after 2030 and pyrolysis facilities after 2040. Critical materials include vanadium in gear steel alloys, magnesium in cast iron and rare earth elements in permanent magnets. These critical materials are subject to high economic importance and supply risk. Secondary supply through recycling can mitigate this criticality. Vanadium in gearbox steel and magnesium in cast iron can be functionally recycled by selective collection within existing recycling infrastructure for specialty steels. It is estimated that with maximum recycling efforts, secondary supply of critical materials can meet up to ~15% of REE, ~30 of V and ~25% of Mg demand by 2050. Dutch wind energy will not provide sufficient scrap magnet material for an industrial size recycling facility dedicated to magnet or REE recovery before 2050.
By determining the potential for material recovery from Dutch wind energy, a timeline is created for potential implementation of domestic recycling and secondary material availability. This is a first step towards circularity goals in 2050 and is intended to provide a sense of scale and timing for material demand, secondary supply and required recycling infrastructure for Dutch wind energy. ... Read more

 Ironmaking in the blast furnace is a rather complex process, governed by the generation of multi-phases and fluid-flow conditions. It includes the reduction of iron ore pellet or sinter material towards producing metallic iron. The metallurgical behaviour of sinter and its reduction rate are controlled by its initial physical and chemical properties, as well as the blast furnace gaseous conditions. To improve and optimize the metallurgical performance of sinter for ironmaking, it is necessary to understand the fundamental mechanisms of phase equilibria, microstructural transformations and reaction kinetics as relevant to different sinters in the upper shaft down to the reserve zone of the blast furnace. The objective of the present MSc research is to study the sinter solid state reduction reactions that take place in terms of thermodynamics and metallurgical kinetics when varying the initial material composition under certain temperature and gas atmosphere conditions.
 Six pilot scale sinter materials with strongly variable bulkmineralogical and chemical composition were sized down to fractions of 250-500μm,being a grain range adequately fine to isolate microstructural effects, whileexcluding the impact of meso-porosity and mechanical fractures (>1 mm), as practically aspossible. A industrial sinter sample, obtained from the production lineof Tata Steel Ijmuiden was included in order to verify potential differences inreduction. The starting materials were characterized with XRD, XRF, sizedistribution and BET measurements.
 Thirty six (36) isothermal reduction experiments were performed in the TGA and GERO furnace under two set of conditions; i) T=750^oC/XCO=0.55/N₂=0.5, ii) T=950^oC/XCO=0.65/N₂=0.5 simulating point-conditions of the BRASS test, as relevant to the stability field of Wüstite and solid state reduction. The reduction experiments were interrupted at different reduction times. The 36 reduced samples were further analysed with XRD for phase quantification to then be placed in polished sections for microscopical analysis. The materials were examined under Reflected Light Optical (LOM) and Scanning Electron (SEM) microscopes in order to verify microstructural changes, visualize phase transitions and identify existing stable and meta-stable phases. In total 396 microscopical images were produced. The results of the experiments were compared with thermodynamic models, which show which phases and reduction degree are theoretically expected at equilibrium.
 Hereby,based on research results, the study attempted to give answers to the initialreseach questions in order to confirm or deny the research hypothesis. The mainfindings of the study were mostly qualitative, referring to the mineralogicalchanges observed during reduction and their impact on reduction kinetics.Results verified that starting composition and mineralogy influencesreducibility kinetics, while the way minerals impact reducibility is dependedon the imposed conditions. It was observed that at T= 950^oC/XCO=0.65/N₂=0.5, the differences between the reduction rates of low and high basicitysamples become smaller, due to enhancement of the relative reduction progressof minerals like precipitated Magnetite. At T=750^oC/XCO=0.55/N₂=0.5,the transition of Magnetite to Wüstite occurred in different stages ofreduction progress, amongst samples. In addition, the effect of mineralogy and microstructure could not be distinguished ofthat of open particle porosity.

 Findings obtained from the XRD analysis andmicroscopy verified that Hematite is the most pronemineral to reduction followed by SFCA, while Magnetite stays stable for longer.Even within the samemicrostructure, Hematite is clearly reduced to a greater distance from theparticle exterior than the Ca-ferrites surrounding it, and its normalizeddecrease in the XRD analyses from its initial concentration is clearly fasterthan that for any of the Ca-ferrites (SFCA, CF2). Moreover, the relative reduction of Hematite and SFCA differsbetween the two sets of conditions; More reducing conditions converge thereduction progress of the two phases, due to SFCA’s greater reduction. The reduction fronts of Hematite and SFCA converge in a single sinter particlewith higher temperature conditions.Two types of unreacted SFCA wereidentified under the microscope, one Fe-rich SFCA and one Ca-Al-rich SFCA. SFCA1 starts reducing into a multiphase intergrowth, comprised by an Fe-rich pathand a Ca-Si-Al -rich path, while the high Ca type SFCA demonstrates one -to-onephase transition.

The reduction experiments inthe GERO showed that longer-time experiments always give the same samplesequence based on reduction progress; WCS108 is the most reduced, followed byWCS90, WCS86, the industrial sinter MH1785, WCS62 and WCS94, whilst noparticular differences were observed in reduction behavior of the industrialsinter MH1785/21 compared to pilot-pot sinter samples. In addition, the comparisons between the reductionexperiments and the thermodynamic predictions showed that there is mostly qualitative agreement, but results differ quantitatively.

Finally, based on the  findings of the research work conducted, the study hypothesis was confirmed; Sinter microstructure and mineralogy influences sinter solid statereduction.  ... Read more

The main goal of this research is to get a better understanding of the manganese refining path in the steelmaking converter process. This study focuses primarly on manganese refining due to manganese mass transfer, between metal containing droplets and oxidized slag in the metal-slag emulsion zone, in the top part of the steelmaking converter. Manganese and iron content in the slag heavily influences the slag formation path. Controlling the slag viscosity is essential for controlling the efficiency of the steelmaking process and to preserve the quality of the final steel product. Manganese refining in the steelmaking process occurs in three phases, the primary oxidation phase, the reversion phase and the secondary oxidation phase. This manganese reversion phase is hard to predict and influences the final amount of manganese in the end steel product. In order to raise understanding of the reversion behaviour of manganese in the converter, unique data gathered from in situ measurements done in the EU funded IMPHOS project is utilised. The following research questions were formulated and answered in this study: 1. Are thermodynamic models for manganese distribution calculation applicable for the prediction of the three different behavioral phases of manganese in IMPHOS? 2. What is the influence of the slag-metal emulsion droplets size on the manganese refining behaviour? 3. What is the influence of metal-slag data input obtained from 2 different heights in IMPHOS, on the final resulting manganese behaviour in the kinetic model made in python? 4. Were there any chemical deviations in different zones of the hot metal bath during IMPHOS project sampling? IMPHOS heat S1836, S1841, S1844, S1845 were selected and analyzed on their theoretical thermodynamic equilibrium behaviour for manganese. This analysis was done with Suito No. 3 and Morales and Fruehan equilibrium partition model. Furthermore, the heats slag composition data, hot metal data and converter process variables were used as input in a kinetic model. The model is simulating the micro and macro kinetic behaviour of manganese in the converter emulsion zone with a fixed time step of 1s. The mass transfer in the model is based on Fick's first law of diffusion and uses penetration theory by Higbie, to describe mass transfer along metal droplet boundaries. Parameters such as the manganese mass transfer and the predicted manganese content in the hot metal bath were evaluated to validate the model with the measured concentration reported in the IMPHOS study. Bulk chemical analysis is done on physical samples from heat S1836 cup height 2. This is done to check the inhomogeneity in the hot metal bath and the possibility of different reaction zones in the converter process. The thermodynamic evaluation performed on IMPHOS data showed the difficulty of thermodynamic models derived from laboratory tests, to describe the manganese equilibrium behaviour within the converter. Suito no 3 model gave a better prediction of the manganese distribution than the Morales and Fruehan model. The results from the kinetic model showed a slower primary oxidation and reversion behaviour of manganese compared to the original data. This is mainly due to the manganese equilibrium behaviour of the thermodynamic model and the negligence of the manganese refining in the jet impact zone and metal-slag interface. The model gave a better prediction when a small size droplet range was considered, which implies that the smaller size droplets less than 100 micron are significantly contributing to the manganese transfer from metal to slag and vice versa. The present study reveals that droplet size play an important role and thus need further investigation to accurately describe the size fraction for the accuracy of the kinetic model. The difference between metal-slag data input from the different IMPHOS cup height 4 and 5 on the outcome of the thermodynamic evaluation and kinetic model results, proved to be small enough to be considered negligible. The results from the sample analysis showed deviations for carbon and phosphorus in the new examined cup height 2. These measurements were taken at a high position in the hot metal bath and were different from the measured concentration in the bottom of the hot metal bath. This can indicate deviations in chemical content in the hot metal bath during the original IMPHOS research. More heat data of height 2 , close to the bath surface, is required to confirm this finding. ... Read more