Germany’s hidden treasures - part 3
Forgotten natural resources
Different to common public perception, Germany has significant mineral resource potential. There is, for example, the rare-earths occurrence near Storkwitz in Saxony. Back in the days of the GDR, geologists discovered carbonatites enriched with light rare-earth elements and niobium, a heavy metal that is needed for specialty steels. At the time, the scientists estimated that the occurrence held about 38,000 tons of rare earths and 8,000 tons of niobium. But given that there was no interest in rare earths for smartphones or catalytic converters at the time, this potential was soon forgotten.
“By contrast with our domestic resources of copper, lithium and tin, which are a focus of interest, exploiting the Storkwitz deposits hardly makes sense economically at present time,” Richard Gloaguen explains. He and his team of 20 researchers at HIF address issues such as how mineral raw material exploration can be conducted in a socially-acceptable context and which non-invasive methods can be used to minimize environmental and noise pollution at the same time.
In order to get closer to the Earth’s resources, the researchers take to the air: “Using cameras and special sensors for exploration from a bird’s eye view is a socially and environmentally-friendly approach,” explains Gloaguen. To this end, his researchers work with a series of drones which, depending on their load-bearing capacity, are equipped with high-performance cameras and sensors. “The drones deliver the data for mapping the Earth’s surface and point out indicators for the presence of raw materials below ground,” says Gloaguen. “The results help us to draw up the most diverse measures for developing environmentally benign exploration. Above all, we can tell people in the areas affected exactly what exploiting the raw materials will mean for them and for nature, which methods will be used and what the geologists on the spot will have to reckon with.”
Research in color: the minerals’ signature
Instead of turning up for exploration with diggers, pneumatic hammers and other heavy equipment, the HIF team uses so-called passive methods. The cameras and sensors on the drones capture the sun’s reflection from the Earth’s surface. Because minerals reflect the sunlight very differently and with their own particular characteristics, the spectrum of reflected light may be interpreted in terms of mineralogy. “Our color sensors capture far more than red, yellow and blue in all their different nuances and can thus read the signature of the respective minerals,” says Richard Gloaguen, describing the procedure. Another method with the same goal is to measure magnetism and electrical resistance, which most notably differentiate iron-rich minerals from the surrounding rock.
In addition to this, the exploration researchers test laser-induced fluorescence sensors by illuminating the material from the sky with a laser beam and thus exciting fluorescence in the material. The latter depends on the absorption spectrum of the respective minerals present as well as on the properties of the laser beam and, therefore, uncovers very precise information about the material. “This is all made possible by very high-performance data processing which already exploits the potential of machine-learning and artificial intelligence,” says Richard Gloaguen. “We want to use it to support the geologists’ work and provide them with three-dimensional images of the areas explored. Together with them and in close cooperation with sociologists we can develop scenarios for extracting raw materials in a socially and environmentally-friendly way.”
And this is something that has also caught the attention of the mining community worldwide. The European Union has assigned Richard Gloaguen’s division a leading role in coordinating the recently-launched EU project INFACT (Innovative Non-Invasive Fully Acceptable Exploration Technologies). It is a challenging task: In the next three years, the project partners are supposed to investigate the potential of exploration that is not only highly-efficient, but also environmentally and socially benign. This will be underpinned by concrete data and experience – so that we shall still have enough raw materials in future to go new ways in the industrial and energy sectors, for our prosperity and for the sustainable quality of life. And, last but not least, for all the computers on which future articles on research and development can be written – with the help of the sustainable use of raw materials. They don’t need to be heavy, but it would be good if what they described was weighty.
Author: Marcus Schick
G. Angerer, P. Buchholz, J. Gutzmer, C. Hagelüken, P. Herzig, R. Littke, R.K. Thauer, F.-W. Wellmer: Rohstoffe für die Energieversorgung der Zukunft: Geologie, Märkte, Umwelteinflüsse, Schriftenreihe Energiesysteme der Zukunft, 2016.
Rohstoffe für die Energiewende. Wege zu einer sicheren und nachhaltigen Versorgung. acatech – Deutsche Akademie der Technikwissenschaften, Nationale Akademie der Wissenschaften Leopoldina, Union der deutschen Akademien der Wissenschaften, Berlin 2017.
S. Jakob, R. Zimmermann, R. Gloaguen: The need for accurate geometric and radiometric corrections of drone-borne hyperspectral data for mineral exploration: MEPHySTo – A toolbox for pre-processing drone-borne hyperspectral data, Remote Sensing, 2017 (DOI: 10.3390/rs9010088)