ACID MINE DRAINAGE NEAUTRALIZATION CAPACITY OF MAJOR ROCK TYPES FOUND IN MAINE

Historically, massive sulfide deposits have been mined in Maine for metals, including gold, copper, silver, and zinc. Massive sulfide deposits contain abundant sulfide minerals including pyrite and chalcopyrite which produce sulfuric acid when exposed at Earth’s surface. This acidity can run off into nearby surface waters, lowering the pH and affecting ecosystems. We ran a series of experiments to test the hypothesis that common rock types found in Maine can be used to neutralize acid mine drainage. Experiments were carried out in batch reactors containing 10^-3, 10^-4 and 10^-5 molal sulfuric acid solutions along with five grams of eight different rock types found in Maine: granite from Mount Waldo, calcareous turbidite from the Vassalboro Formation, basalt and schist from the Ellsworth Formation, meta-limestone from Thomaston, serpentinite from Little Deer Isle, schist from the Perry Mountain Formation, and glacial till from Bald Mountain. Results show that the meta-limestone (TL) has the greatest rate of hydrogen consumption, followed by basalt (EB), serpentinite (DIS), calcareous turbidite (VF), the glacial till (BMGT), and the granite (MWG) and two schists (WMS and EF), which consume similar concentrations of hydrogen ions.