Evaluation of the potential release of toxic elements from gold ores and cyanidation tailings in a high sulphidation mining district

The Furtei gold mine in Sardinia (Italy) exploits a volcanic-hosted high-sulphidation epithermal deposit. Large amounts of high sulphide materials derived from exploitation are present in open pits, waste rock dumps and cyanidation tailings impoundment. Analyses of waters draining the mining area and laboratory leaching tests showed that waste rock dumps and mineralized rocks have a high potential for acid drainage generation and release of heavy metals. The mineralogical assemblage strongly influences the composition of leachates. Leachates from cyanidation tailings show variable pH (between 6.2 and 9.7, depending on sulphide content of the solid); cyanide concentration varies between 110 μg/l and about 3 mg/l, whereas heavy metals content in leachates is mostly within the limits of Italian regulations for industrial discharges. The overall results provide useful data for the implementation of reclamation programs.