Geophysicist Michael Becken on the -Sensational Find- in Sweden and the Involvement of the University of MünsterSome observers speak of a "sensational find", others warn against too great expectations. The fact is that a few days ago, experts in Kiruna in northern Sweden found the largest deposit of so-called rare earths in Europe to date. Scientists from the Westfälische Wilhelms-Universität (WWU) Münster were also involved in the exploration work. Kathrin Kottke and Norbert Robers spoke with Michael Becken from the Institute of Geophysics about the significance of the discovery and the further progress of the work.
How did they know to "search" in Sweden in the first place - were there any preliminary investigations or special rock and soil formations that suggested a possible find?
It has been known since the 1960s that rare earths exist in Kiruna. The Swedish mining company LKAB operates one of the largest iron ore mines in the world there, and the rare earth metals occur in association with the iron ores. Incidentally, they also occur with phosphorus-bearing minerals, which are significant because phosphorus is also a critical raw material needed primarily for the production of fertilizers. The find is thus the result of years of exploration work, from which it can be estimated how large the deposit is and that mining could be economical.
What are rare earths, and which of them were discovered in Sweden?
Rare earth metals comprise a group of 17 elements in the periodic table. They are not rare in the earth’s crust, but they occur very rarely enriched, which makes them difficult to extract. For the deposit near Kiruna, LKAB reports an average concentration of 0.18 percent of rare earth oxides, based on analysis of drill core material. This is a very low concentration compared to, for example, the iron ores at Kiruna, but it is typical for rare earth deposits of this type.
What are they used for?
Rare earth metals are needed for many high technologies, but especially for the production of permanent magnets for electromobility and wind turbines. They are technically important, and they are mainly found in China. That is why these elements are classified as critical raw materials - and why the deposit in Sweden is so important for Europe.
Can you at least give an estimate of the volume of the fund in Sweden?
It is assumed that there are about one million tons. This corresponds to about six to eight times the current annual global consumption.
How did it come about that the University of Münster is involved in the research?
The University of Münster has been coordinating the "Desmex" project since 2015. The project aims to develop helicopter-based geophysical measurement methods that can be used to explore raw material deposits at depths of up to 1,000 meters. Specifically, this involves measurement concepts, sensors, data processing and imaging. In the meantime, we are also using a multicopter equipped with measurement sensors. The field named Per Geijer near Kiruna was selected as one of several test sites because the iron ore deposits there form a particularly good contrast to the surroundings and lie at a depth of over 1,000 meters, i.e. the target depth.
What role does your subject, i.e. geophysics, play in this?
It is important to note that geophysics does not allow us to specifically explore individual minerals, but rather to map the physical properties of entire rock formations. In the case of Kiruna, these are primarily the iron ore layers. Thus, our images indirectly help in the exploration of deposits, for example to define suitable drilling points.
After the discovery, mining in Kiruna is scheduled for the coming years. What challenges and risks are associated with this?
Of course, mining engineers who deal with extraction processes and mining can answer this question much better than I can. Basically, however, mining is complex and expensive. Whether economic mining will really be possible in the future is still an open question at the moment. According to the Swedish mining operator, it will take another five to eight years of preparatory work before mining can actually begin.
Doesn’t such mining also have consequences for the environment and nature?
In general, any kind of raw material extraction is an intervention in nature and leaves damage in its wake. At the same time, these raw materials are needed to implement the energy transition. I therefore think it is a good idea to extract raw materials needed in Europe from domestic deposits under European labor and environmental standards instead of exporting these risks. It also reduces our dependence on third countries.
Is it possible to make surprise finds in other regions or countries?
The present find was neither a chance discovery nor a surprise, but the result of a very targeted exploration. In Europe, especially in Greenland, two other sites with larger rare earth metal deposits are known. These deposits are also currently being intensively investigated.
The instruments developed in the project were tested in 2018 in the Per Geijer exploration area near Kiruna, where the experts have now also discovered the rare earths. A core element is the magnetic field sensor technology developed in this project. The sensors are towed by a helicopter over the exploration area - they record the magnetic induction field generated by current injection underground. With the help of complex computer simulations, the team uses the measurement data to calculate three-dimensional geophysical models that map the geological structures.