Precious and critical metal potential of historic Cu-Au-As mine waste in the Eastern Alps

For the world to transition from fossil fuels to renewable energy, a significant amount of raw materials is required. For example, in order to build the electricity grid needed for the move to ‘green’ electricity, we need to mine the same amount of copper in the next 30-40 years as in the entire history of mankind combined (Cathles and Simon, 2024). The difficulty of finding large geogene deposits of copper and other critical metals, requires us to identify alternative sources of these critical and strategic metals.

We note that for much of human history, the extraction of metals from natural ores was significantly less efficient than it is today. Therefore, the mine waste of historic districts can still contain considerable quantities of raw materials. This is particularly true for the historic Cu-Au-As mining districts of the Eastern Alps. Recovery for the produced metals (such as copper and gold) were between 50-66%, with the rest ending up as mine waste, largely in the form of sulfide minerals (Paar et al., 2006). These sulfide rich mine wastes can also be a source of critical metals that tend to associate with Au and Cu (i.e. As, W, Bi, In, Te; Gopon et al., 2019; Goebel, 2024; Hiller, 2024), as well as groundwater contamination.

By combining whole rock geochemistry, geophysics, and advanced micro- to atomic-scale characterization techniques we have produced estimates of the raw material potential of the 4000+ Cu-Au-As mine dumps found throughout the Eastern Alps. We will show examples from historic Cu-Au-As districts from the Hohe Tauern to the Fischbacher Alpen, and discuss which raw materials are present, in what form they are present, and how sulfide minerals are able to host such a diversity of important metals. The environmental impact of these sulfide rich mine wastes will also be discussed, as well as the possibility of remediating these former mine sites by re-mining the mine dumps.

The mining and metallurgical techniques required to process weathered, low grade, and arsenic rich ore pose a significant challenge. To this end we have started a combined geological, geophysical, environmental, metallurgical, and mining engineering study focused on a particularly well-suited Cu-Au mining district in the vicinity of Spielberg, Austria (Flatschach, Styria). This work is part of the SCIMIN project, which is looking at four mining waste sites across Europe (Spain, Bosnia, Sweden, Austria) and is funded by the European Union as part of the Horizon Europe Research and Innovation Programme (No. 101177746).