Abatement of Acid Mine Drainage by Encapsulation of Acid-Producing Geological Material

摘要

A novel coating technology was developed to prevent pyrite oxidation and acid production in coal waste. The mechanism underlying this technology involves leaching coal waste with a coating solution composed of H2O2, KH2PO4, and sodium acetate (NaAC). During the leaching process, H2O2 oxidizes pyrite and produces Fe3+ so that iron phosphate precipitates as a coating on pyrite surfaces. The purpose of NaAC in the coating solution is to eliminate the inhibitory effect of the protons, produced during pyrite oxidation, on the precipitation of iron phosphate. In the study, it was shown that iron phosphate coatings on pyrite surfaces could be established by consuming 5% to 10% of the available pyrite, under a wide range of conditions. It was also demonstrated in the study that iron phosphate coatings on pyrite surfaces could prevent pyrite oxidation and acid production in coal waste.