Reactions
in ARD
1) 2 FeS2 + 7 O2 + 2 H2O = 2 Fe2+ + 4 SO42- + 4 H+
Pyrite + Oxygen + Water = Ferrous Iron + Sulfate +
Acidity
2) 4 Fe2+ + O2 + 4 H+ = 4 Fe3+ + 2 H2O
Ferrous Iron + Oxygen + Acidity = Ferric Iron +
Water
3) 4 Fe3+ + 12 H2O = 4 Fe(OH)3 ¯ + 12 H+
Ferric
Iron + Water = Ferric Hydroxide + Acidity
4) FeS2 + 14 Fe3+ + 8 H2O = 15 Fe 2+ + 2 SO42- + 16 H+
Pyrite + Ferric Iron + Water = Ferrous Iron + Sulfate +
Acidity