Green mining techniques in metal extraction

Louise Smyth

New research flags up growing importance of green mining techniques in metal extraction

An international research team involving scientists from the Biotechnology Research and Information Network (BRAIN) has succeeded in extracting nearly the entire copper content from local shale deposits, harnessing micro-organisms in combination with a bio-leaching process. The research results highlight the importance of green and urban mining to extract and recover metals from ores and waste streams.

The recently established BRAIN BioXtractor also offers various bio-based solutions for the enrichment of precious metals such as gold and silver for the purposes of an efficient circular economy.

For the French-German research project, co-managed by the French Geology and Mining Research Bureau (Bureau de recherches géologiques et minières) and the German Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it was key to develop an energy- and raw material-efficient recovery process with a small ecological footprint to use this local primary resource.

In the early extraction phase, the bacteria employed in the bio-leaching process first convert insoluble ore minerals into water-soluble salts. Downstream, a bio-chemical precipitation process then helps recover up to 97% of the dissolved copper.

Within the research project, BRAIN brought its specific capabilities to bear, which helped identify carbonate-dissolving, metal-resistant micro-organisms from its proprietary BioArchive. This ‘toolbox of nature’ contains more than 53,000 micro-organisms. In addition, BRAIN also provided its distinct expertise in the realm of physiological and genetic micro-organism characterisation.

“This successful research project underscores the increasing significance of green mining and urban mining, both of which are areas in which we conduct intense research. We focus on the low-impact and efficient extraction and recovery of precious metals, such as gold, silver and other technology metals, from ores and waste streams. Source materials include electronic scrap, incineration bottom ashes and metallurgical slags,” says Dr Guido Meurer, member of the management board and unit head producer strain development at BRAIN.

New ideas

New processes that allow for the sustainable extraction and recovery of metals are an increasingly important field of research and development, especially for regions such as Germany, where raw materials are scarce. Experts also predict a strongly increasing demand in copper to meet global needs – to usher in the era of electric vehicles, for example.

Says Dr Esther Gabor, programme manager Green & Urban Mining at BRAIN: “There is an increasing demand in precious metals, which play a key role in many high-tech applications. Based on biotechnological processes, BRAIN has developed various bio-based solutions for green and urban mining as they are essential for an efficient circular economy.”

A recently finalised demonstration unit, the BRAIN BioXtractor, offers powerful and safe biological process solutions to extract and recover precious metals from side and waste streams as well as from primary resources. Currently the system is being made ready to get explored by enterprises interested in a test phase prior to joint further development and commercialisation or licensing the technology.

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