Effect of sulfide impurities on the reactivity of pyrite and pyritic concentrates: a multi-tool approach

Sulfide mineral oxidation, primarily pyrite and pyrrhotite, generates acid mine drainage during weathering. Successful management of acid generating w astes entails the suppression of the initiation of oxidation reactions. The reactivity of pyrite depends on ore mineralogy, including the effects of a ssociated sulfide impurities. The electrochemical surface characterization study using cyclic voltammetry with carbon paste electrodes containing mine rals particles (CPE-Mineral) is an effective tool for demonstrating how the Various mineral characteristics work together to influence the overall rea ctivity of the mineral. This study was supported by chemical, mineralogical and leachate chemistry data. The results show that the presence of other s ulfides in contact with pyrite at the beginning of the weathering process i s the most important parameter affecting pyrite reactivity, which is likely to be oxidized and passivated. In more advanced stages of leaching, minera l coatings which passivate the pyrite surfaces tend to play the most import ant role in defining the reactivity of pyrite. The electrochemical response of pyritic samples in conjunction with the evolution of the chemical quali ty of the leach solution in the simple experimental device here used, could then provide valuable information on acid mine drainage generation. (C) 20 01 Elsevier Science Ltd. All rights reserved.