Characterizing Tailings Impoundment at the Closed Hammaslahti Cu-Zn Mine, Finland

B035 CHARACTERIZING TAILINGS IMPOUNDMENT AT THE CLOSED HAMMASLAHTI CU-ZN MINE FINLAND Summary 1 *H.VANHALA 1 M-L.RAISANEN 2 T.HUOTARI 1 T.VALJUS 1 J. LEHTIMAKI 1 and I. SUPPALA 1 1 Geological Survey of Finland (GTK) Betonimiehenkuja 4 FIN-02150 Espoo Finland Acid mine drainage (AMD) results when sulphide bearing tailings sand is exposed to air and water. Oxidation of sulphide minerals and release of acid and dissolved metals in tailings impoundments can last for tens to hundreds of years. Rehabilitation risk analysis and risk assessment of the old tailings impoundments require detailed information on the structure mineralogy and chemistry as well as