Applied Geochemistry

Crystal chemistry of tellurium in arsenian pyrite – Economic and environmental implications

The European Union classified Tellurium as an energy-critical element for the rapidly growing sector of green energy technologies. Currently, most Tellurium is recovered as a by-product from non-ferrous metal mining, providing little opportunity to increase the Tellurium supply independantly based on current extraction methods. Hence, a shortage in Tellurium is likely to be reached in the near future due to its increasing demand.

Pyrite occurs as an important component in many deposits, forms under variable fluid conditions and can incorporate a large number of trace elements with economic but also environmental significance, such as arsenic, gold and tellurium. Preliminary results show that up to 64% of bulk ore Tellurium may be hosted in pyrite and thus it represents and economically important Tellurium source. In principle, Tellurium either occurs as inclusions or as lattice substitutions. However, the crystallographic position and redox state of Te in the pyrite lattice is unknown, but an essential requirement to modify extraction methods to improve the Tellurium recovery. If Tellurium is not recovered and sent to tailings or released from roasters, it may have an eco-toxicological impact. The mobility of Tellurium also strongly depends on its redox state, and hence such information would allow to evaluate the environmental risk potential of mine waste.

For this purpose, pyrites containing arsenic and tellurium are synthesized at the TU Berlin in cooperation with the GFZ Potsdam under different conditions in the laboratory (see figure) and characterized by means of LA-ICP-MS. In addition, X-ray absorption spectra at the tellurium LIII edge are to be recorded at the ESRF and compared with ab inito modeling to gain further insights into the incorporation of tellurium in arsenian pyrite at the atomic level.

Publications

Börner, Frederik, et al. "Fingerprinting fluid evolution by trace elements in epithermal pyrite, Vatukoula Au-Te deposit, Fiji." Ore Geology Reviews 137 (2021). doi.org/10.1016/j.oregeorev.2021.104314

Funding:

DFG

Project coordination:

Dr. Manuel Keith (Uni Erlangen)

Project scientists TU Berlin:

Dr. Martin Kutzschbach, Dr. Ferry Schiperski

Other project partners:

Christoph Kusebauch (GFZ Potsdam), Frederik Börner (Erlangen)