Table 1.

Main reactions in the oxidation of pyrite

FeS2 (pyrite) + H2O + 3½ O2 → FeSO4 + H2SO4
CaCO3 (calcite) + H2SO4 + H2O → CaSO4.2H2O (gypsum) + CO2
2 FeSO4 + H2SO4 + ½ O2 → Fe2(SO4)3 + H2O
3 Fe2(SO4)3 + 2 K2Al4Si6Al2O20(OH)4 (illite) → 2 K(Fe)3(SO4)2(OH)6 (jarosite)
FeS2 (pyrite) + 7 Fe2(SO4)3 + 8 H2O → 15 FeSO4 + 8 H2SO4
Fe2(SO4)3 + 6 H2O → 2 Fe(OH)3 (goethite) + 3 H2SO4