Effect of Pyrite Oxidation in Soils on Corrosion Behavior of Steel

The oxidation of pyrite in soils causes their acidification under aerated conditions, which may promote the corrosion of buried steel structures. Hence, the purpose of this study was to elucidate the effect produced by the presence of pyrite minerals in soils on the corrosion behavior of steel. In order to assess the fundamental corrosiveness of pyrite toward steel, the chemical properties of its aqueous solution were investigated by conducting short-term laboratory tests. In addition, electrochemical measurements were performed to evaluate the effect produced by the soil particles on the diffusion rates of oxygen and hydrogen ions in the soil medium. The obtained results revealed that the corrosion rate of steel in the pyrite-containing solution was accelerated due to the continuous production of hydrogen ions during the pyrite oxidation under the aerated conditions. However, its magnitude in a water-saturated soil system was not influenced by the oxidation of pyrite, owing to the relatively low diffusion rates of dissolved oxygen and hydrogen ions.