“We are symbionts on a symbiotic planet, and if we care to, we can find symbiosis everywhere.” — Lynn Margulis, 1999

Circular Economy (CE) aims at improving the resource efficiency of our society and decoupling economic growth from resource use. However, entropy and residues are still generated in CE, and resources such as energy, raw materials and water are used throughout the CE processes. The methodology developed in this thesis aims at evaluating and communicating the resource efficiency and environmental impacts of CE systems. Firstly, a digital twin of the system is created using process simulation to obtain detailed mass and energy balances. Then, a set of indicators is obtained for the evaluation of the material recoveries, residues and emissions generated, resource use and environmental impacts (LCA). Exergy indicators such as exergy dissipation and cost are also obtained from the simulation using a dedicated tool developed and implemented within this thesis. This methodology has been applied in three case studies within metallurgy and CE to evaluate, optimize and communicate their resource efficiency and environmental impacts. These case studies are the evaluation of the copper value chain, the comparison between different zinc production routes and the industrial symbiosis between the copper, zinc and cement value chains.

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

Indium gilt als eines der strategischen Metalle für die Technologiebranche. Durch das schnelle Wachstum bei Flachbildschirmen aller Art besteht seit Jahren eine stark wachsende Nachfrage nach Indium. Es wurde ein neuartiger Ansatz der Biolaugung gewählt und innerhalb des BHMZ getestet, Die aus der Biolaugung resultierende Lösung enthielt vereinfacht 1 mg·L-1 Indium sowie jeweils 1 g·L-1 Zink und Eisen. Durch systematische Untersuchung von zahlreichen hydrometallurgischen Methoden zur Metallabtrennung wurde eine auf Flüssig-Flüssig-Extraktion basierte Methode entworfen und erprobt. Der Prozess ermöglicht eine Indiumanreicherung bis zum Indiumhydroxid in einer Reinheit von 99,99 %. Die Chemikalienkosten für diesen Prozess belaufen sich gegenwärtig, bezogen auf den Labormaßstab, auf 189,40 €·kg-1 Indium. Diese liegen unter dem aktuellen Marktpreis von Indium. Die bisherigen Ergebnisse belegen, dass in der Realisierung dieses Verfahrens im technischen Maßstab erhebliches wirtschaftliches Potential steckt.

Oil palm dominates global oil production, trade, and consumption. Nigeria is one of the leading palm oil producers and consumers. A significant challenge of the palm oil industry is to reduce the environmental impacts (e.g. pollution and carbon footprint) and integrate a circular economy in operation. This study aims to comparatively quantify the environmental impacts of technologies used by different mills. We applied a life cycle assessment in the case of Nigeria. The study covers the reception and processing of fresh fruit bunch (FFB) to end-product palm oil. The inputs include generated empty fruit bunch (EFB), mesocarp fibre, palm kernel shell, palm oil mill effluent, diesel, water and all outputs to the environment for a functional unit of 1-tonne FFB. The results showed that large-scale mills perform worse (468 kg CO₂-eq per t FFB) than the semi-mechanised and smallholder mills in effects on climate change but better in the other impact categories, including human toxicity, ecotoxicity, and fine particulate matter formation. In large-scale mills, the climate change impacts decrease by 75% when the raw palm oil mill effluent (POME) is used in composting EFB. Similarly, climate change impacts reduce by 44% when biogas from POME substitutes diesel in the semi-mechanised and smallholder mills. We conclude that regulatory measures are needed to ensure improved management practices in the production processes. Particular attention should be paid to the generation and reuse of biomass and POME. This study provides a handy reference to assist the sustainable energy transition in Nigeria’s and other parts of sub-Saharan Africa’s oil palm industry to mitigate climate change and form a cleaner bioeconomy.

In den vergangenen Jahren hat die zunehmende Knappheit von Ressourcen, insbesondere im Bereich der Gesteinskörnung im Bauwesen, sowie die Anerkennung der Notwendigkeit von Kreislaufwirtschaft im Betonbau dazu geführt, dass der Fokus verstärkt auf der Nutzung von Recyclingmaterialien liegt. Vor allem rezyklierte Gesteinskörnungen werden vermehrt eingesetzt. Da diese jedoch Auswirkungen auf die Frisch- und Festbetoneigenschaften haben können, ist es wichtig, ihren Einfluss zu untersuchen. Dieser Artikel befasst sich daher mit der Herstellung, dem mechanischen Verhalten, den Dauerhaftigkeitseigenschaften sowie dem Brandverhalten von Betonen, die rezyklierte Gesteinskörnung enthalten. Zusätzlich werden wissenschaftliche Begleitprogramme wie ein AiF Verbundforschungsprojekt am VDZ/KIT vorgestellt. Da eine positive Ökobilanz das Ziel bei der Verwendung von Recyclingmaterialien ist, wird dieser Aspekt ebenfalls in diesem Beitrag beleuchtet. Weil vor allem der Zement entscheidend für die Ökobilanz von Betonen ist, wird zudem der Ansatz der Verwendung von Recyclingmehlen als Zementhauptbestandteil betrachtet. / In recent years, the increasing scarcity of resources, particularly in the area of aggregates in the construction industry, as well as the recognition of the need for a circular economy in concrete construction, has led to a greater focus on the use of recycled materials. Recycled concrete aggregates in particular are increasingly being used. However, as these can have an impact on the properties of fresh and hardened concrete, it is important to analyse their influence. This article therefore deals with the production, mechanical behaviour, durability properties and fire behaviour of concretes containing recycled aggregates. In addition, accompanying scientific programmes such as an AiF joint research project at the VDZ/KIT are presented. As a positive environmental impact is the goal when using recycled materials, the life cycle assessment of concrete with recycled aggregates is highlighted in this article. As cement in particular is decisive for the environmental impacts of concrete, the approach of using recycled concrete fines as a cement main constituent is also addressed.

Das aktuell vorherrschende lineare Wirtschaftsprinzip ist für viele Umweltprobleme verantwortlich. Neben der immensen Umweltverschmutzung sorgt der stetig wachsende Ressourcenverbrauch für eine zunehmende Verknappung vieler wertvoller Rohstoffe. Ein intelligentes Kreislaufwirtschaftskonzept wie Cradle-to-Cradle kann diesen Problemen entgegenwirken. Für eine erfolgreiche Umsetzung von Cradle-to-Cradle werden unternehmerische Ansätze benötigt. Im Rahmen dieses Artikels werden vier Konzepte untersucht, die in einer Kreislaufwirtschaft implementiert werden können. Diese sind Design für Demontage, Produkt-Service-Systeme, Take-back Strategien und Reverse Logistics. Für jeden dieser vier Ansätze werden die Voraussetzungen sowie Barrieren hinsichtlich der Umsetzung innerhalb eines Kreislaufwirtschaftssystems aufgezeigt. Zudem wird dargelegt, dass sie im Cradle-to-Cradle-System realisierbar sind. Weiterhin werden reale Beispiele in Form von Unternehmen vorgestellt, die die verschiedenen Modelle bereits erfolgreich umgesetzt haben. Alle vier untersuchten Konzepte sind für ein Kreislaufwirtschaftssystem unter Beachtung der Cradle-to-Cradle-Kriterien geeignet. / The currently prevailing linear economic principle is responsible for many environmental problems. In addition to the immense environmental pollution, the constantly growing consumption of resources is causing an increasing shortage of many valuable raw materials. An intelligent circular economy concept such as Cradle to Cradle can counteract these problems. Entrepreneurial approaches are needed for a successful implementation of Cradle to Cradle. This article examines four concepts that can be implemented in a circular economy. These are design for disassembly, product service systems, take-back strategies, and reverse logistics. For each of these four approaches, the prerequisites as well as barriers regarding the implementation within a circular economy system are shown. In addition, it is shown that they can be implemented in a cradle-to-cradle system. Furthermore, real examples are presented as companies that have already successfully implemented the various models. All four concepts examined are suitable for a circular economy system in compliance with the Cradle to Cradle criteria.

Die Landesstrategie stellt ausgehend von einer Analyse der Situation der Kreislaufwirtschaft im Freistaat Sachsen und unter Berücksichtigung der Ziele und Schlussfolgerungen des am 7. November 2023 verabschiedeten Kreislaufwirtschaftsplans ergänzende Ziele und Maßnahmen für Recycling, Abfallvermeidung, Wiederverwendung sowie ressourcenschonendes Prozess- und Produktdesign, zur Reduktion des Ressourcenverbrauchs und zur Schließung regionaler Wertschöpfungsketten dar. Weiterhin werden Maßnahmen zur Stärkung der Nutzung von Recyclingbaustoffen und zur Minimierung der Deponierung von mineralischen Abfällen, zur Stärkung der Inanspruchnahme von Reparaturen, zur Entwicklung innovativer Technologien im Bereich Abfallvermeidung, Wiederverwendung und Recycling und zur Unterstützung der öffentlich-rechtlichen Entsorgungsträger in der Landesstrategie beschrieben. Redaktionsschluss: 29.05.2024

Der Textilindustrie wird hinsichtlich umweltschädlicher Emissionen ein schlechtes Zeugnis ausgestellt. Bisweilen nimmt sie sogar einen unrühmlichen zweiten Platz ein und hat damit unweigerlich eine grosse Verantwortung um das global gesetzte 1,5-Grad Ziel (COP 21) zu erreichen. Konkret müssen bis 2030 die von diesem Industriezweig ausgehenden Treibhausgasemissionen um 45 % reduziert werden. Neben neuen Konsummustern und Geschäftspraktiken gilt es insbesondere die produktionsbasierten Emissionen zu vermindern (Berg, 2020).

The continuously growing social and political pressure to provide sustainable products is forcing also the lightweight industry to rethink current development and manufacturing processes. While established development approaches in lightweight engineering mainly focus on technical and economical product requirements they usually do not consider sustainability criteria. To address these challenges, a new class within the lightweight disciplines is proposed—the Neutral Lightweight Engineering. Its basic goal is to integrate sustainability criteria in all decisions along the development chain of a lightweight component. The decision makers in lightweight engineering thereby have to consider the whole life cycle of a product system from material sourcing to end-of-life part management. To implement this idea, advanced development methods are necessary, using established and emerging materials as well as efficient production and end-of-life strategies. This concept article introduces the idea of Neutral Lightweight Engineering and exemplary highlights some of its aspects before the background of scientific literature.