Rhenium solubility in chloride-bearing and oxidizing fluids

Rhenium (Re) is an extremely rare element with average abundances of 0.7 ppb in the Earth’s crust. It is a ‘critical metal’ due to its strongly limited natural occurrence while it is essential and at present non-replaceable for several industrial applications. The main host phase for Re is molybdenite (100 - 3000 ppm Re) which is mined mainly from porphyry copper deposits (PCDs). Formation of PCDs is based on magmatic-hydrothermal fluids that transport and enrich metals during ascent to shallower levels within the Earth’s crust. While enrichment processes of main metals of PCDs and other magmatic-hydrothermal ore deposits (e.g., Fe, Cu) have been studied in detail, only few works so far focus on secondary metals probably due to challenging experimental setups (detection of extremely high dilution levels of Re at high PT conditions). However, this knowledge is essential particular for ‘critical’ metals to facilitate and support efficient and sustainable exploration of ore deposits.