Oxidative Dissolution Mechanisms of Pyrite {100} and {210} Faces: An Atomic Study

Abstract

ABSTRACT The oxidative dissolution of pyrite discharging into tailing pond as gangue minerals attracts intensive interesting as this forms the main source of acid mine drainage. However, the related dissolution mechanisms on the individual crystal faces of pyrite particles remain unclear. In this study, the oxidative dissolution mechanisms of pyrite {100} and {210} faces under acidic and neutral conditions were investigated. The results indicated that the dissolution rate of pyrite correlates positively to the reactivity of pyrite face. The reactivity of {210} was higher than that of {100}, mainly due to the geometric arrangements of the atoms. In addition, the oxidative dissolution on pyrite faces follows the chemical reaction model. Further density functional theoretical (DFT) calculation indicated that {210} face showed obvious Fe-S breakage and S-S formation while {100} face only showed slight atoms movement during relaxation process. Moreover, a higher conductivity and electron transfer ability of {210} faces than that of {100} face was found base on scanning electrochemical microscopy. This study therefore provides new insights into oxidative dissolution of pyrite crystal faces at an atomic level.