Suppression of microbial pyrite oxidation by fatty acid amine treatment

Abstract

Numerous techniques have been investigated in the past for the treatment and control of acid mine drainage (AMD). While some of these techniques are directed towards the treatment of the resulting drainage, others are directed towards the prevention of AMD at-source. The at-source prevention methods have been found to be promising since, if achieved, they can provide permanent solutions to AMD problem. However, though the bacterium, Thiobacillus ferrooxidans plays an important role in the formation of AMD, and is unavoidable in AMD systems, many of the at-source AMD control and prevention techniques have not been evaluated in the presence of this bacterium. In this study, the stability of fatty acid amine (FAA) treated pyrite in the presence of T. ferrooxidans was investigated. The rate limiting reactions during the oxidation of pyrite, in the absence and presence of the bacterium, was also investigated. The FAA treatment reduces the rate of both the chemical and biological oxidation of the pyrite. In the absence of the bacteria, ferrous to ferric ion oxidation is the rate limiting reaction in pyrite oxidation, while in its presence, ferric oxidation of pyrite is the rate limiting reaction.