ABSTRACT
This Chapter focuses on mainly in the biotic oxidation of pyrite. Pyrite is an extremely insoluble mineral but it is well known that it is able to undergo dismutation. Dismutation is the process by which pyrite at low pH undergoes oxidation/reduction with one of its sulfur atoms acting as electron donor and the other sulfur atom acting as electron acceptor. Mechanisms of bacterial pyrite oxidation have mainly been derived from investigations of metal bioleaching. The mechanisms of bacterial pyrite oxidation have been studied extensively and the results have been discussed in a number of articles. Generally, the mechanisms of pyrite oxidation by bacteria are classified into direct metabolic reactions and indirect metabolic reactions. Direct metabolic reactions require physical contact between bacteria and pyrite particles, while indirect metabolic reactions do not require physical contact. Under indirect metabolic reactions, bacteria oxidize Fe2+ to Fe3+, thereby regenerating the Fe3+ required for the chemical oxidation of pyrite.
