Circular economy is a central element in our strategy for a carbon-neutral and sustainable metals industry. Professor Markus Reuter has been one of the main initiators of the circular economy paradigm in the metals industry and works for SMS group since 2020. In this interview, he explains the background to the concept and the opportunities and limitations of circular economy (CE).
Markus Reuter: For 37 years now I have been working in the copper and non-ferrous metals industry and I have always tried to represent it passionately both as an academic and in industry. I have been a professor at TU Delft in the Netherlands, the University of Melbourne, Changsha University China and presently at Curtin Uni in Perth in Australia and most recently at TU Bergakademie in Freiberg, Germany. Among others, I was lead author of the UNEP (United Nations Environment Programme) report on “Metal Recycling: Opportunities, Limits, Infrastructure”. However, I also worked in the metallurgical industry for AngloAmerican and Mintek and also for plant suppliers, e.g. as CTO for Ausmelt in Australia and in Finland.
Markus Reuter: SMS group can play a pivotal role in the transformation of all the metals industries towards a circular economy, especially due to its focus on both steel and copper. We supply the technology to produce and recycle all major metals; therefore we have a significant impact on improving the resource efficiency. Our combination of in-depth metallurgical know-how with engineering skills, digital expertise and plant technology consultancy makes us a key enabler for circularity. We create the plants and have the systems to quantify their impact and thus enable more sustainable metal supply chains, linking mining, scrap, end-of-life products to steel, aluminium, copper and alloys production on a global level.
Markus Reuter: Metals are perfectly suited for a sustainable Circular Economy as we work with elements thence producing either again alloy or pure refined metal. They are extremely durable and can be infinitely recycled without degrading their quality or desired properties.
However, reality is far more complex and the metal wheel shows the connections between the elements. The main message is that you need a base metal industry to make the society's wheels turn. The dark-blue ring in the center of the metal wheel reflects the close interconnected symbiosis between the base-metal sectors that enable the circular economy. This is the ball bearing of modern society. In the next ring there are the elements that dissolve in the carrier metal and can be recovered mainly through pyrometallurgical and smelting processes but also hydrometallurgical. Elements that are collected as oxides, sulphates, chlorides etc. in dust or slime are shown in the third ring. They can be recovered with mainly hydrometallurgical processes, through high-purity metals and compounds. The elements in the outer ring mainly go to lower-value building material or are the inevitable dissipative loss (e.g. expressed in terms of exergy). The metals for which the base metal of that segment can act as a carrier metal are marked with green circles and are compatible with the alloying or chemistry of the sectors. The yellow circles reflect mainly the elements that retain value e.g. as alloying elements in steel, aluminium etc. if scrap is well managed by digital systems as those in the SMS portfolio.
The metal wheel implies that no part can exist on its own. If you want to recycle copper-based materials and associated elements within compounds and products, it must obviously exist in parallel with the other industries, e.g. zinc, lead, tin but also steel, aluminium or magnesium industries. We have to deal with many elements and the ingenuity of the metallurgist lies therein to place them into the right streams using the correct technology to do that efficiently.
Markus Reuter: The image of the closed loop of the Circular Economy is a convenient one. It conveys the impression that everything that enters the cycle also emerges from it in a way that ultimately allows it to be utilized again without the use of energy. The inconvenient truth is that closing the loop is impossible, limited by 2nd thermodynamic law reality! Therefore, an honest discussion involves speaking transparently about losses in the process: in the form of energy, exergy, metals, and dust, for example. These, if quantified well, are the proxy for technological and economic limits to closing the loop.
Nevertheless, it is the ambition of SMS group, to be the technological leader for metallurgical process equipment that pushes recycling rates to their thermodynamic and technological limits, maximizing the transfer processes between the molten, liquid and gas phases in our technologies. In the end, that is where the limits of circularity are to be found on a technology level. Of equal and even larger importance is maximizing the transfer at the interface between the different stakeholders in the CE, this means communicating and interacting with policy and society at large.
Markus Reuter: The products we are dealing with become rather complex, comprising of many elements, materials and minerals that are linked to produce the functionality of that product. That brings with it a lot of ingenuity and complexity to deal with to actually recover them back in an economic way and once again return functional materials of value in modern products. Take your smartphone: it is a complex functional mix of many hundreds of metals, alloys, materials, plastics, and glass in close proximity.
It does not take much imagination to picture how complex it is to separate these components again physically and chemically and to recover the metals in the end. Therefore, recycling means to understand how these elements interact in a chemical way as dictated by the periodic table within the context of economically viable reactor technology and systems we translate into flowsheets. Managing these using digital platforms or digital twins is the future to visualize in the end the losses from the system as well as most importantly the exergy dissipation.
When we speak about Circular Economy, we always try to bring the metals back into the purity that is required to produce new high-tech products. For me that's the true definition of circularity in circular economy, and that is a hard task. SMS has the competence and values to enable this.