Bacterial Leaching as a Green Approach to Recovering Critical Raw Materials
Antimony and copper belong to the group of critical raw materials whose availability the European Union seeks to improve. In the case of antimony, the EU is 100% dependent on imports, with China accounting for 56% of global production. Antimony is considered a material supporting the transition to a green economy, but it is also gaining new applications in innovative energy-storage technologies, such as molten-salt batteries that allow the accumulation of electricity from renewable sources. Copper, on the other hand, plays a key role in electrical infrastructure and electronics.
Researchers from the Institute of Geotechnics of the Slovak Academy of Sciences (SAS) present the project Bio4Sb, aimed at extracting antimony and copper from primary sources using advanced biotechnological methods with an emphasis on environmental sustainability.
“The process is based on optimizing the biological leaching of tetrahedrite concentrate using specific bacteria at ambient temperature, which represents an environmentally less demanding and energy-efficient method of metal recovery compared to conventional mineral separation and chemical processing. The main advantage of this green approach is that it integrates three scientific disciplines — geochemistry, metagenomics, and biohydrometallurgy,” explains Dr. Lenka Hagarová from the Department of Mineral Biotechnology, Institute of Geotechnics SAS.
Tetrahedrite is a complex sulfide mineral with a high content of copper, antimony, and a relatively high silver content. A major natural source of this mineral is the Mária mine (Strieborná vein) near Rožňava, where drainage water flows directly into the Slaná River.
“The first metagenomic analyses of the mine water showed that iron-oxidizing bacteria dominate in the samples. These microorganisms can accelerate the dissolution of sulfide minerals and can therefore be used for bioleaching tetrahedrite. Laboratory tests with bacteria from collection cultures confirmed that this process can yield over 80% copper. Antimony either precipitates as secondary minerals or dissolves into the solution, achieving a recovery rate of about 13%. Bioleaching activity has also been confirmed by the first experiments with bacterial cultures isolated directly from the mine water,” adds Dr. Hagarová.
More Information
The Bio4Sb project (Antimony recovery by bioleaching of tetrahedrite as a primary source of critical raw materials) is part of Slovakia’s Recovery and Resilience Plan under the NextGenerationEU mechanism. It is one of several projects granted to the Institute of Geotechnics SAS in 2024.,
The project began in August 2024 and will run for two years. Its goal is to enable the recovery of antimony and copper in a more environmentally friendly way — with lower energy consumption and without toxic by-products. Bio4Sb thus directly supports the EU’s priorities in securing the supply of critical raw materials and developing sustainable technologies.
More details about the research can be found on the project website: www.bio4sb.eu or in the article Bioleaching of Tetrahedrite by Iron- and Sulfur-Oxidizing Bacteria, that have been published in the journal Journal of Sustainable Metallurgy. Another article, focused on the microbiological evaluation of mine water using metagenomic analyses, will be published in Frontiers in Microbiology.
Edited by Monika Tináková
Foto: Lenka Hagarová, Ústav geotechniky SAV, v. v. i.