Acid mine drainage prediction by acid-base accounting tests in abandoned mine tailings from Sardinia

Acid-base accounting tests were performed on tailings from two major abandoned Pb-Zn Sardinian mines: Montevecchio and Monteponi, The compositions of these tailings is characterized by low amounts of calcite, and major amounts of other carbonates (siderite at Montevecchio, dolomite and smithsonite at Monteponi). By combining standard acid-base accounting procedures with mineralogical observations, we obtained what we believe are the most realistic estimates of acid producing/buffering properties of the materials. The Montevecchio samples have neutralization potentials between 4.5 and 16.0 kg CaCO3/t, and about 1 wt. % sulfide sulfur: they are potential sources of acid drainage. The Monteponi samples show neutralization potentials between 33.1 and 53.6 kg CaCO3/t, with 0.4-0.5 wt.% sulfide sulfur; they are not expected to produce acid drainage.