Oxidative Dissolution of Sulfide Minerals in Single and Mixed Sulfide Systems under Simulated Acid and Metalliferous Drainage Conditions

Abstract

Chalcopyrite, galena, and sphalerite commonly coexist with pyrite in sulfidic waste rocks. The aim of this work was to investigate their impact, potentially by galvanic interaction, on pyrite oxidation and acid generation rates under simulated acid and metalliferous drainage conditions. Kinetic leach column experiments using single-minerals and pyrite with one or two of the other sulfide minerals were carried out at realistic sulfide contents (total sulfide <5.2 wt % for mixed sulfide experiments), mimicking sulfidic waste rock conditions. Chalcopyrite was found to be most effective in limiting pyrite oxidation and acid generation with 77–95% reduction in pyrite oxidation over 72 weeks, delaying decrease in leachate pH. Sphalerite had the least impact with reduction of pyrite dissolution by 26% over 72 weeks, likely because of the large band gap and poor conductivity of sphalerite. Galena had a smaller impact than chalcopyrite on pyrite oxidation, despite their similar band gaps, possibly because of the greater extent of oxidation and the significantly reduced surface areas of galena (area reductions of >47% for galena vs <1.5% for chalcopyrite) over 72 weeks. The results are directly relevant to mine waste storage and confirm that the galvanic interaction plays a role in controlling acid generation in multisulfide waste even at low sulfide contents (several wt %) with small probabilities (≤0.23%) of direct contact between sulfide minerals in mixed sulfide experiments.

Electrochemistry of Sulfides: Process and Environmental Aspects

“…Galvanic interactions determine the reactivity of sulfide minerals. Therefore, galvanic interactions must be studied to predict the generation potential of AMD and to estimate the rate of transition of environmentally hazardous metals and metalloids into the environment [19,131].…”

Influence of Galvanic Interaction between the Iron Grinding Medium and Chalcopyrite on Collectorless Flotation Behavior of Chalcopyrite: Experimental and Density Functional Theory Study

“…Chalcopyrite, which is commonly found in porphyry copper deposits, constitutes approximately 70% of the global copper reserves . Furthermore, the incomplete recovery of sulfide minerals can result in the production of acid mine drainage (AMD) from the tailings, which leads to water contamination. , Therefore, clean and sustainable recycling of chalcopyrite can significantly promote energy conservation and emission reduction at the source of copper industrial production.…”