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A mineral that is difficult to crack meets a raw material that is increasingly in demand in the electronics and semiconductor industry: In multi-stage smelting and refining processes, raw tin is processed from a concentrate of the mineral cassiterite (tin oxide) with the addition of carbon. In a research project funded by the Dr Erich Krüger Foundation, a team from TU Bergakademie Freiberg is now testing how the metal can be extracted without carbon and therefore without direct CO2 emissions. The team's method could be of particular relevance for the local extraction of tin in Europe.
In a recent scientific publication in the Journal of Sustainable Metallurgy, the researchers propose a new process in which the direct CO₂ emissions from tin production are close to zero. In contrast, up to 2.5 tonnes of CO2 are currently emitted to produce one tonne of tin, according to the Bundesgesellschaft für Geowissenschaften und Rohstoffe (p. 12). The new two-stage process could save these emissions, as a small amount of hydrogen is used instead of carbon in the first step.
Pretreated with hydrogen, around half of the tin concentrate (tin dioxide) is converted directly into pure tin. Water vapour and a tin-containing slag are also produced. "Cassiterite is difficult to crack, i.e. it cannot be leached, but the slag produced can. The residual tin can then be extracted from the slag by chemical leaching at low temperatures," says project leader Professor Alexandros Charitos.
From computer modelling to laboratory tests
"We were able to confirm in laboratory tests what our computer models predicted: In the first step, instead of carbon, a very small amount of hydrogen is sufficiently used - yet 50 per cent of the cassiterite already becomes raw tin, without any direct CO2 emissions." The team and other working groups at the Institute of Nonferrous Metallurgy and High-Purity Materials are now investigating in more detail how the remaining tin can be purified using environmentally friendly methods after the chemical leaching of the slag and extracted by electrolysis in the final step.
Great potential for the Ore Mountains and Europe
The team's findings could be of particular relevance to the Free State of Saxony, as exploration projects for tin-bearing ores are underway in Geyer, Gottesberg and Tellerhäuser, for example. "The new process harbours great potential for environmentally friendly extraction in Saxony and Europe, but also for the recycling of tin. After all, almost all of the world's tin is currently produced in countries with weak governance and often with rarely recorded environmental impacts," Charitos says.
Research project is funded by the Dr Erich Krüger Foundation.
The aim of the foundations funding is always to support practical and application-related research at TU Bergakademie Freiberg, to implement its results in Saxony and to create jobs. Cooperation with companies from the region is therefore an integral part of the programme. In addition to application-related research projects, the foundation also supports the acquisition of large-scale equipment and scholarships for young scientists. With its "Krüger Colloquium" series of events, Freiberg University attracts personalities from science, business and politics to give lectures to a wide audience. The Krügerhaus, which exhibits a collection of minerals from Germany, and the "Chile-Haus" guest house are available to the university thanks to the foundation's commitment.
Alexandros Charitos, alexandros.charitos@inemet.tu-freiberg.de
https://link.springer.com/article/10.1007/s40831-025-01096-1
Metals in powder form in small crucibles have been used for the expiriments.
Source: Crispin Mokry
Copyright: TU Bergakademie Freiberg / C. Mokry
Criteria of this press release:
Journalists
Materials sciences
transregional, national
Research projects, Research results
English
Metals in powder form in small crucibles have been used for the expiriments.
Source: Crispin Mokry
Copyright: TU Bergakademie Freiberg / C. Mokry
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