Natural and Built Environments Research Centre, School of Natural and Built Environments , University of South Australia , Mawson Lakes , South Australia 5095 , Australia.
Future Industries Institute , University of South Australia , Mawson Lakes , South Australia 5095 , Australia.
Environ Sci Technol. 2018 May 1;52(9):5349-5357. doi: 10.1021/acs.est.7b05558. Epub 2018 Apr 17.
Although the acid generating properties of pyrite (FeS) have been studied extensively, the impact of galvanic interaction on pyrite oxidation, and the implications for acid and metalliferous drainage, remain largely unexplored. The relative galvanic effects on pyrite dissolution were found to be consistent with relative sulfide mineral surface area ratios with sphalerite (ZnS) having greater negative impact in batch leach tests (sulfide minerals only, controlled pH) and galena (PbS) having greater negative impact in kinetic leach column tests (KLCs, uncontrolled pH, >85 wt% silicate minerals). In contrast the presence of pyrite resulted consistently in greater increase in galena than sphalerite leaching suggesting that increased anodic leaching is dependent on the difference in anodic and cathodic sulfide mineral rest potentials. Acidity increases occurred after 44, 20, and 12 weeks in the pyrite-galena, pyrite-sphalerite, and the pyrite containing KLCs. Thereafter acid generation rates were similar with the Eh consistently above the rest potential of pyrite (660 mV, SHE). This suggests that treatment of waste rocks or tailings, to establish and maintain low Eh conditions, may help to sustain protective galvanic interactions and that monitoring of Eh of leachates is potentially a useful indicator for predicting changes in acid generation behavior.
尽管黄铁矿（FeS）的产酸特性已被广泛研究，但电偶作用对黄铁矿氧化的影响及其对酸性和含金属排水的影响在很大程度上仍未得到探索。相对电偶效应对黄铁矿溶解的影响与相对硫化物矿物表面积比一致，在批式浸出试验（仅含硫化物，控制 pH）中闪锌矿（ZnS）的影响更大，而在动力学浸出柱试验（KLCs，非控制 pH，>85wt%硅酸盐矿物）中方铅矿（PbS）的影响更大。相比之下，黄铁矿的存在总是导致方铅矿的浸出率比闪锌矿更高，这表明阳极硫化物的浸出率增加取决于阳极和阴极硫化物矿物的平衡电位之间的差异。在黄铁矿-方铅矿、黄铁矿-闪锌矿和含有黄铁矿的 KLCs 中，分别在 44、20 和 12 周后出现酸度增加。此后，随着 Eh 始终高于黄铁矿的平衡电位（660 mV，SHE），酸生成速率相似。这表明处理废石或尾矿以建立和维持低 Eh 条件可能有助于维持保护性电偶相互作用，并且浸出液 Eh 的监测可能是预测酸生成行为变化的有用指标。
