CDTN, Centro de Desenvolvimento da Tecnologia Nuclear, Av. Presidente Antônio Carlos, 6.627, UFMG, Pampulha, Belo Horizonte, Minas Gerais, CEP: 31270-901, Brazil; Departamento de Geología, Facultad de Ciencias, Universidad de Salamanca, Plaza de Los Caídos S/n, Salamanca, 37008, Spain.
CDTN, Centro de Desenvolvimento da Tecnologia Nuclear, Av. Presidente Antônio Carlos, 6.627, UFMG, Pampulha, Belo Horizonte, Minas Gerais, CEP: 31270-901, Brazil.
Chemosphere. 2021 Aug;277:130131. doi: 10.1016/j.chemosphere.2021.130131. Epub 2021 Mar 18.
The scavenging of soluble metals by iron (Fe) and aluminium (Al) oxyhydroxides is a natural process that occurs in acid mine drainage (AMD). This phenomenon is relevant to the immobilization, transport, and recovery of important natural resources such as rare earth elements (REE) and uranium (U). Furthermore, understanding the players and the reactions that govern the scavenging of REE and U by Fe and Al oxyhydroxides in aqueous systems is fundamental for natural and engineering sciences and for environmental management. In this scenario, the current work investigated the role of iron in the co-precipitation of REE and U when treating effluents by pH neutralization in an AMD system located in Brazil. The research employed water sampling, co-precipitation batch experiments, sequential extraction, X-ray diffraction and Fe Mössbauer spectroscopy. The results revealed that the presence and the amount of Fe in the initial solution can influence the REE removal efficiency positively. The effect of the addition of Fe over the REE removal efficiency was irrelevant when the pH of the AMD was raised to values equal to 7-8. The scavenging of U was not influenced by the addition of Fe to the AMD. The sequential extraction results showed that precipitates containing higher amounts of Fe tend to be less labile. The Fe Mössbauer spectra revealed that the REE can occupy iron sites in the structure of the amorphous precipitates. The findings of the current study can be extrapolated to other AMD systems and contribute to the development of novel REE recovery and hydrometallurgical techniques.
铁 (Fe) 和铝 (Al) 氢氧化物对可溶性金属的清除是酸性矿山排水 (AMD) 中发生的自然过程。这种现象与稀土元素 (REE) 和铀 (U) 等重要自然资源的固定、迁移和回收有关。此外，了解控制 Fe 和 Al 氢氧化物在水相体系中清除 REE 和 U 的作用物和反应是自然科学和工程科学以及环境管理的基础。在这种情况下，目前的工作研究了在巴西 AMD 系统中通过 pH 中和处理废水时铁在 REE 和 U 共沉淀中的作用。研究采用了水样采集、共沉淀批实验、连续提取、X 射线衍射和 Fe Mössbauer 光谱。结果表明，初始溶液中 Fe 的存在及其含量可以积极影响 REE 的去除效率。当 AMD 的 pH 值升高到 7-8 时，添加 Fe 对 REE 去除效率的影响并不重要。U 的清除不受向 AMD 添加 Fe 的影响。连续提取结果表明，含有较高 Fe 量的沉淀物往往不太易变。Fe Mössbauer 光谱表明，REE 可以占据无定形沉淀物结构中的铁位。本研究的结果可以外推到其他 AMD 系统，并有助于开发新型 REE 回收和湿法冶金技术。
