Modeling the oxidation mechanism of pyrite and arsenopyrite – connection to acid rock drainage

Acid rock drainage (ARD) is hazardous to the environment and it is caused by the oxidation of sulfide minerals leading to the formation of acids and, consequently, enhancing the dissolution of the rocks. Therefore, ARD leads to the acidification of aquifers and mobilization of heavy metals in the environment. Sulfide minerals are the main source of noble metals such as copper and gold (besides zinc and lead), hence, ARD is the main environmental concern in the mining regions. Arsenopyrite is normally associated to other sulfide minerals. Its presence enhances the environmental problem since the poisoning arsenic is also released in the environment due to ARD phenomenon. In this chapter, the contribution of the computer modeling to the understanding of the oxidation mechanism of sulfide minerals is reviewed. The challenge for modeling such a complex reaction involving water and oxygen is highlighted. The effects of the pyrite/arsenopyrite interface to their oxidation mechanism are also discussed in the light of the recent reports.