Urban mining recovers metals from electronic waste and mining tailings. Currently, this process is still energy-intensive and environmentally burdensome. Prof. Dr. Timm John’s team is working on solutions. 

Mr. John, why do you believe urban mining is one key to sustainable resource usage?

In which products and industries are strategically and economically critical elements found in large, economically viable concentrations? This is the central question addressed by urban mining. This is the case with electronic waste and tailings piles from past mining operations. To give an example: While each smartphone contains only a small amount of gold, between 30 and 50 milligrams, one ton of smartphones, however, which corresponds to about five to six thousand smartphones, contains more gold than one ton of gold ore, which must be extracted from mines at great logistical expense. The gold already incorporated into smartphones produced globally is worth several billion euros. From a purely technological standpoint, extracting metals from electronic waste is a relatively simple process. However, it has so far been very energy-intensive and environmentally damaging; it involves high temperatures and the use of corrosive liquids.

What research questions are your department addressing in this context? What role does the newly founded Center for Sustainable Resources (CSR|Berlin) play?

In a project funded by the Werner Siemens Foundation, we are experimenting with ionic liquids developed by the research group led by Prof. Dr. Sebastian Hasenstab-Riedel. The project is also part of the research conducted by CSR|Berlin. These liquids are capable of very effectively leaching metals from tailings and electronic waste at low temperatures. Additionally, we are working on incorporating the liquids and waste products used into a closed-loop process; in other words, recycling them. Ultimately, achieving zero waste will not be possible. But we see the potential to make these processes, which have been very energy-intensive up to now, significantly more efficient and environmentally friendly in the future.

That sounds quite intriguing from a resource perspective. How application-oriented is your research? Can we expect quick results?

Personally, I consider myself part of the basic research community. However, since there are already patent applications and industry contacts in this area, I am optimistic that the first commercial applications could emerge within five to ten years. The energy savings are enormous compared to currently established processes. My optimism also stems from the fact that we have seen significant progress in this field of research over the past ten years. At the same time, dependence on rare earths and critical elements is increasingly coming into the spotlight of German politics.

What are the biggest obstacles?

Since the infrastructure for circular economy processes in industry and commerce is not yet sufficiently developed, it is still easier to purchase raw materials for products from “new” conventional resources. At the same time, structural conditions prevent quick successes, such as long-term investment planning and contracts in mining or ownership structures in the electronics waste sector. From our perspective, German policymakers must not cede these industries and opportunities to other countries but rather develop their own strategies for “getting a foot in the door” in the primary ore sector as well as in urban mining.

What role do you see for research in this field of action? And how do your activities fit into the international context?

Research currently plays a clear and important role in setting the agenda and providing impetus, thereby promoting greater awareness of the issue in politics and business. As researchers, we can take on an important initiating role, for example through pilot projects in the Global South. It helps not to think in terms of a perfect solution, but rather to develop the necessary processes and collaborations step by step. Other countries are also making significant contributions to research in this field. However, we at Freie Universität are currently particularly well-positioned in the area of ionic liquids, a fact that is also reflected in the interdisciplinary composition of our CSR|Berlin team. We are pleased that the Executive Board has recognized the exceptional quality of our collaboration and has recently made a decisive contribution to the establishment of CSR|Berlin through infrastructure commitments.

The interview was conducted by Judith Hübner, Katrin Schweigel, and Andreas Wanke.
It first appeared in Freie Universität Berlin’s 2026 Sustainability Report.