Centre Eau, Terre et Environnement (ETE), Institut national de la recherche scientifique (INRS), 490 rue de la Couronne, Québec, QC, Canada.
Research Institute on Mines and Environment (RIME), Université du Québec en Abitibi-Témiscamingue (UQAT), 445 boulevard de l'Université, Rouyn-Noranda, QC, Canada.
Sci Total Environ. 2020 Aug 25;732:139225. doi: 10.1016/j.scitotenv.2020.139225. Epub 2020 May 8.
Increasing use of rare earth elements (REEs) in modern technologies and existing or expected imbalances between demand and supply have led many countries, including Canada, to consider the exploitation of their own REEs primary sources. The objective of this study is a thorough characterization of the flotation tailings generated during the pre-concentration of REEs from a carbonatite type deposit with the aim of predicting their geochemical behaviour over time. These tailings were characterized based on physicochemical and mineralogical properties. Weathering cells were also used to assess the impact of temperature (3 and 19 °C) on the geochemical behaviour of the tailings exposed to a sub-arctic climate. Because the tailings consisted mainly of carbonates (97.4%) and had very high neutralization potential (859 kg CaCO/t) relative to their acidity potential (3.94 kg CaCO/t), no acid mine drainage (AMD) is anticipated. Compared to regional environmental standards and guidelines, the concentrations of Cd (0.20 μg/l), Zn (17 μg/l), and Pb (close to 4 μg/l) in leachates obtained during kinetic testing may be considered as potentially problematic. Finally, the results of the weathering cells at 3 °C indicate that the exposure to low temperatures may increase the concentrations of elements leached from the tailings. This study confirms that low temperatures and freeze-thaw events, which occur readily in a sub-arctic climate, may impact the geochemical behaviour of tailings produced from the extraction of REEs from carbonatite type deposit.
现代技术中越来越多地使用稀土元素 (REE)，以及需求和供应之间现有的或预期的不平衡，促使包括加拿大在内的许多国家考虑开发自己的 REE 主要来源。本研究的目的是对从碳酸岩型矿床中预先浓缩 REE 过程中产生的浮选尾矿进行全面表征，旨在预测其随时间的地球化学行为。这些尾矿是根据物理化学和矿物学特性进行表征的。风化电池也用于评估温度（3 和 19°C）对暴露于亚北极气候的尾矿的地球化学行为的影响。由于尾矿主要由碳酸盐（97.4%）组成，并且相对于其酸度潜力（3.94 kg CaCO/t）具有非常高的中和潜力（859 kg CaCO/t），预计不会产生酸性矿山排水（AMD）。与区域环境标准和指南相比，在动力学测试过程中获得的浸出液中 Cd（0.20μg/l）、Zn（17μg/l）和 Pb（接近 4μg/l）的浓度可能被认为是潜在的问题。最后，3°C 下风化电池的结果表明，暴露于低温可能会增加尾矿中浸出元素的浓度。这项研究证实，在亚北极气候下容易发生的低温和冻融事件可能会影响从碳酸岩型矿床中提取 REE 产生的尾矿的地球化学行为。
