Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, SK S7N 5E2, Canada.
Environ Sci Technol. 2011 Jul 1;45(13):5557-63. doi: 10.1021/es200107m. Epub 2011 May 27.
2-Line ferrihydrite, a form of iron in uranium mine tailings, is a dominant adsorbent for elements of concern (EOC), such as arsenic. As ferrihydrite is unstable under oxic conditions and can undergo dissolution and subsequent transformation to hematite and goethite over time, the impact of transformation on the long-term stability of EOC within tailings is of importance from an environmental standpoint. Here, studies were undertaken to assess the rate of 2-line ferrihydrite transformation at varying As/Fe ratios (0.500-0.010) to simulate tailings conditions at the Deilmann Tailings Management Facility of Cameco Corporation, Canada. Kinetics were evaluated under relevant physical (~1 °C) and chemical conditions (pH ~10). As the As/Fe ratio increased from 0.010 to 0.018, the rate of ferrihydrite transformation decreased by 2 orders of magnitude. No transformation of ferrihydrite was observed at higher As/Fe ratios (0.050, 0.100, and 0.500). Arsenic was found to retard ferrihydrite dissolution and transformation as well as goethite formation.
2 线水铁矿是铀矿尾矿中一种主要的铁元素吸附剂，也是砷等关注元素（EOC）的主要吸附剂。由于在氧化条件下，水铁矿不稳定，随着时间的推移会发生溶解，并随后转化为赤铁矿和针铁矿，因此从环境角度来看，转化对尾矿中 EOC 的长期稳定性的影响非常重要。在这里，进行了研究以评估在不同的 As/Fe 比（0.500-0.010）下 2 线水铁矿的转化速率，以模拟加拿大 Cameco 公司 Deilmann 尾矿管理设施的尾矿条件。在相关的物理（1°C）和化学条件（pH10）下评估了动力学。随着 As/Fe 比从 0.010 增加到 0.018，水铁矿的转化速率降低了 2 个数量级。在更高的 As/Fe 比（0.050、0.100 和 0.500）下未观察到水铁矿的转化。发现砷会阻碍水铁矿的溶解和转化以及针铁矿的形成。
