An epithermal, high-sulphidation, gold deposit, hosted in Tertiary volcanic rocks, was exploited from 1997 to 2003 at Furtei in Sardinia (Italy). Gold and silver were recovered by cyanidation from oxidized ores, and by flotation from sulphide ores. Following bankrupt in 2008, sulphide-rich materials derived from exploitation, and processing residues were left on site. Cyanide in the tailings impoundment underwent natural degradation. In 2011, cyanide concentrations below the Italian limit for industrial effluents were observed, but concentrations of dissolved toxic components, especially ammonium, aluminum, arsenic, copper, iron and manganese, in the tailings impoundment were much above standard values. Analyses of waters draining the mining area showed that waste materials disposed on dumps, flotation tailings confined in an impoundment, and mineralized rocks exposed in open pits have a high capacity of acid drainage generation and release of contaminants. During the rainy season, the waste rock dumps produce acidic, highly contaminated drainage that flows downstream of the mine and poses a hazard to a cultivated plain. Useful data for the implementation of reclamation programs are provided.
Impact of gold mining on the aquatic system: a case study at Furtei (Sardinia, Italy)
CIDU, ROSA;DA PELO, STEFANIA;FRAU, FRANCO
2011-01-01
Abstract
An epithermal, high-sulphidation, gold deposit, hosted in Tertiary volcanic rocks, was exploited from 1997 to 2003 at Furtei in Sardinia (Italy). Gold and silver were recovered by cyanidation from oxidized ores, and by flotation from sulphide ores. Following bankrupt in 2008, sulphide-rich materials derived from exploitation, and processing residues were left on site. Cyanide in the tailings impoundment underwent natural degradation. In 2011, cyanide concentrations below the Italian limit for industrial effluents were observed, but concentrations of dissolved toxic components, especially ammonium, aluminum, arsenic, copper, iron and manganese, in the tailings impoundment were much above standard values. Analyses of waters draining the mining area showed that waste materials disposed on dumps, flotation tailings confined in an impoundment, and mineralized rocks exposed in open pits have a high capacity of acid drainage generation and release of contaminants. During the rainy season, the waste rock dumps produce acidic, highly contaminated drainage that flows downstream of the mine and poses a hazard to a cultivated plain. Useful data for the implementation of reclamation programs are provided.
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