Silica/fly ash-based technology for controlling pyrite oxidation

摘要

The results of pyrite oxidation in mining areas are very low pH and elevated concentrations of iron and sulfate in the groundwater. Pyrite oxidation is therefore the main cause for acid mine drainage production. One approach to prevent AMD production is microencapsulation of pyrite crystals with an iron-oxide/silica coating (Zhang and Evangelou, 1998). Coating prevents diffusion of oxygen and Fe(sup 3+) to the crystal's surface and they are no longer able to oxidize it. The objective of this portion of the study was to test the hypothesis that fly ash is able to provide the necessary silica for iron-oxide/silica coating formation on the pyrite surfaces thus, decreasing pyrite oxidation and diminishing acid mine drainage production.