College of Geoscience and Surveying Engineering, China University of Mining & Technology, Beijing, 100083, China.
Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Department of Environment Science and Engineering, Southwest University, Chongqing 400716, China.
Chemosphere. 2018 Oct;209:381-391. doi: 10.1016/j.chemosphere.2018.05.192. Epub 2018 Jun 6.
Realgar (AsS)-rich tailings are iron-deficient arsenical mine wastes. The mechanisms and products of the dissolution of realgar by Acidithiobacillus ferrooxidans (A. ferrooxidans) in the presence (0.2 g and 2 g) and absence of zerovalent iron (ZVI) are investigated for three stages (each of 7 d with fresh A. ferrooxidans medium addition between the stages). SEM-EDX, FTIR, XPS and selective extraction analysis are used to characterize the solid-phase during the experiments. ZVI addition causes the systems to become more acid-generating, although pH increases are observed in the first day due to ZVI dissolution. Arsenic is released to solution due to realgar oxidation (∼30 mg L in the 0 g ZVI system in Stage I), but low concentrations are observed in the ZVI-added systems (<5 mg L) and in Stages II and III of the 0 g ZVI system. As(III) dominates the released As(T) at day 1 (83-89% of As(T)), but is largely oxidized to As(V) at day 7 of each stage (53-98% of As(T)). Arsenic attenuation is attributed to the formation of mixed As-Fe oxyhydroxides and oxyhydroxy sulfates that take up released arsenic and are abundant in the 2.0 g ZVI system, and to passivation of the realgar surface. Consequently, a new strategy that combines A. ferrooxidans and exogenous ZVI addition for treating in-situ iron-deficient realgar-rich tailings is proposed, although its long-term effects need to be monitored.
雄黄（AsS）丰富的尾矿是铁贫砷矿山废物。研究了在有（0.2 g 和 2 g）和无零价铁（ZVI）存在下，嗜酸铁氧化菌（A. ferrooxidans）溶解雄黄的机制和产物，分为三个阶段（每个阶段 7 天，阶段之间添加新鲜 A. ferrooxidans 培养基）。SEM-EDX、FTIR、XPS 和选择性提取分析用于表征实验过程中的固相。ZVI 的添加使系统产生更多的酸，但由于 ZVI 的溶解，在第一天观察到 pH 值升高。由于雄黄氧化，砷释放到溶液中（在第 I 阶段的 0 g ZVI 系统中约为 30 mg/L），但在添加 ZVI 的系统中观察到浓度较低（<5 mg/L），在 0 g ZVI 系统的第 II 和第 III 阶段也是如此。As(III)在第 1 天（As(T)的 83-89%）占释放的 As(T)的主导地位，但在每个阶段的第 7 天大部分被氧化为 As(V)（As(T)的 53-98%）。砷的衰减归因于形成混合的 As-Fe 氢氧化物和氢氧化物硫酸盐，它们吸收释放的砷，在 2.0 g ZVI 系统中含量丰富，以及雄黄表面的钝化。因此，提出了一种结合 A. ferrooxidans 和外加 ZVI 添加的原位处理铁贫雄黄丰富尾矿的新策略，尽管需要监测其长期效果。
