Markus, you have dedicated almost your entire professional life to metallurgy, recycling, and the circular economy. You’ve worked in universities and research institutes, and now at SMS, focusing on product design. What is so interesting about this topic?
Markus Reuter: There is something fascinating about taking what many consider post-consumer goods or simply scrap and recovering metals and other materials in their pure form from such complex functional material combinations. Recycling is a complex undertaking and is often more difficult than recycling your morning cup of coffee into its ingredients: pure water, sugar, milk, and coffee to create an aromatic new cup. Our Metal Wheel shows this complex puzzle of extractive metallurgy succinctly.
In metals, considerable expertise has to be harmonized to bring them back to the functional purity required to produce new high-tech products. This includes the simulation and twinning of processes within the circular economy paradigm, the design and optimization of metallurgical vessels, automation and digital systems, the construction and commissioning of plants, also applying AI-based surrogate functions, and then linking this back to the design of consumer goods. So, it never gets boring, is stimulating, and immensely creative. Embedding this in the circular economy is a significant, highly relevant, positive, and noble objective that serves our society!
I am recording our conversation with my smartphone. If I purchase a new device in a few years, can we recycle the old one?
Markus Reuter: Every smartphone is a complex functional mix of metals, materials, plastics, and glass, to name the most important ingredients. Physically and chemically separating these components again to ultimately retrieve the metals is an extremely complex task due to their intimately connected functionality.
In 2017, a colleague and I collaborated on a study with the smartphone manufacturer Fairphone. We found that only 30% to 40% of the materials could be recovered, even with a modular design. Our second study in 2019 showed that, with suitable design modifications, the recovery rate can be increased to the 50% to 60% range. This highlights how far we are from achieving true circularity. But within the constraints of functionality, we can push recycling to the limits physics constrains us to. That’s why we must be honest about the “inconvenient truths” of the circular economy.
What are these “inconvenient truths”?
Markus Reuter: Marketing or politics are all too happy to use the circular economy as a buzzword and, let’s be honest, gloss over the underlying physics. As metallurgists, we must first consider the physics within the constraints of the reactors, mills, etc. The ever-present second law of thermodynamics dictates that continuous reuse, reprocessing, renewal, and loss-less recycling are unachievable – we also measure our process efficiencies via exergy. While losses and residues can be minimized, they cannot be eliminated; residues are always created. The apparent closure of one loop might come at the expense of another; closing a material loop often relies on opening an energy loop elsewhere. Therefore, we must always consider raw materials and energy together, and exergy is the best measure for this. There are no simple answers here – at some point, the amount of exergetic effort outweighs the value of the metal content that can be extracted.
Although products can be manufactured entirely from recycled materials, losses will occur during the recovery of those materials. Consequently, the finished product can never be fully recycled due to these unrecoverable losses. Ignoring this principle would hinder impactful innovation – actual resource efficiency can only be determined if losses are taken into account.
Bearing this in mind, our ambition is to always push recycling and metal recovery rates from complex resources, scrap, and end-of-life goods to their thermodynamic, technological, and economic limits. This is a prerequisite for being a technological leader and provider of metallurgical process equipment for recycling and processing. Having said that, metallurgy is just one part of the wheel that makes the circular economy go round.
Who else needs to contribute?
Markus Reuter: The circular economy needs a mindset change along the entire supply chain. Consider, for example, product design. Although one can never recycle 100% of any given product, we can maximize the recovery of metals, alloys, and materials if we integrate product design with metallurgy knowledge and calculate in detail in advance what can be recycled later. By default, we must then be clear that not everything can be converted back into high-quality materials. In many cases, complex mixtures of plastics in products are used as an energy source or as a chemical to enhance extraction. If a product is smartly modularized, the raw materials can be distributed so that each module can be directly recycled with suitable technology and appropriate disassembly. This would make recycling many valuable metals easier while maximizing energy efficiency. However, due to functional complexity, there will always be losses.
In addition, policy also has to play a significant part. Why not introduce a label to provide consumers with information about the recyclability of a product based on good supply chain digital twinning? We have developed simulation models that digitally twin the entire value chain, allowing products’ actual recyclability to be calculated and improved. This enhances transparency for consumers and helps them make fact-based decisions. With the detailed know-how of SMS, we can generate meaningful data to optimize the supply chain’s environmental performance.
Unfortunately, policymakers sometimes have ideas that ignore the realities of process physics. An interesting example is lead. The EU discussed the idea of banning lead. Yes, lead is toxic. However, it is also a metallurgical fact that lead – like copper – is crucial as a metal collector in multi-metal metallurgical recycling, as shown in the metal wheel. Therefore, base metals are essential enablers of the circular economy, as they help recover valuable metals such as gold, silver, bismuth, and antimony. Therefore, the circular economy paradigm is not well-served by banning lead. We must be keenly aware that smelters are an integral part of the critical metallurgical infrastructure, securing the supply of raw materials.
Study metallurgy and help save the world!
What is the role of SMS in the circular economy?
Markus Reuter: Metals processing technology and digitalization are key enablers of the circular economy and are strategically positioned in various areas within it. Process know-how and detailed flow-sheet understanding are, therefore, essential foundations to maximizing recycling rates. They are the DNA of plant design, plant automation, digital systems, project implementation, and so forth – the core competencies of SMS.
Digital twins offer a perfect platform for communicating with internal and external stakeholders based on the results of simulations with different parameters. That’s why we are intensifying our work to understand every detail of recycling and implement this know-how in digital twins. While digital twinning is the foundation for cost definitions and thus for informed joint decision-making with our customers, it is also a precise tool for accurate carbon footprint predictions and planning for complete plants.
How optimistic is your view for the upcoming generations?
Markus Reuter: Youth needs a torch to carry, and SMS has the depth to light that torch of creative energy. We owe it to the next generations to improve the world. We can help pass on that torch, and the older generation can infuse creative energy to keep the flame burning with vigor. Right now, we are seeing progress in so many promising areas. One of the most exciting projects is the world’s largest plant for electronic scrap recycling that we are supplying to Aurubis in the US. This plant will significantly increase the recycling capacity for this kind of material. In addition, we are expanding our plant portfolio for recycling materials such as catalysts, slags, batteries, and metal-bearing scraps and minerals.
As a concluding remark, the circular economy of metals and end-of-life products requires one thing above all: metallurgists. We need creative, in-depth knowledge and understanding in the field of metallurgy embedded in circular economy thinking to increase the efficiency and effectiveness of recycling and process metallurgy. That is why I teach process and system simulation at Bergakademie Freiberg (Germany) and the exergy of systems at Curtin University in Australia. I always tell my students: “Study metallurgy and help save the world!” Come and help develop new processing solutions within the circular economy paradigm. This worthwhile career has enriched my life for over 45 years in so many ways!