A review: Pyrite oxidation mechanisms and acid mine drainage prevention

Sulfide oxidation, part of sulfur's biotic/abiotic cycle, is an important natural phenomenon. However, because of the sulfide's association with metallic ores and fossil fuels in the form of pyrite (FeS2) and the world's increasing demand for metals and fossil fuels, sulfide oxidation in nature is in some state of perturbation. This perturbation, which results from land disturbances (e.g., mining, and/or ore processing), produces acid drainage often enriched with heavy metals. This acid drainage, commonly referred to as acid mine drainage (AMD), has become an economic and environmental burden. This review deals with abiotic/biotic modes of pyrite oxidation and the mechanistic involvement of OH‐, O2, and Fe3+ in the pyrite oxidation process in low/high pH environments. Also included is recent evidence on the potential involvement of CO2 in catalyzing pyrite oxidation in near‐neutral and alkaline environments. Finally, the review deals with various pyrite‐oxidation control approaches, the merits of these approaches, and some new and promising pyrite microencapsulation techniques currently under development in our laboratory.