Comparison of the precipitation of calcium carbonates to the dissolution of uranium in uranium mine tailings

铀矿尾矿中碳酸钙沉淀与铀溶解的比较

• 批准号: 493381-2015
• 负责人: Grosvenor, Andrew
• 金额: $ 5.8万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=602604
• 关键词: Comparison; precipitation; calcium; carbonates; dissolution

The natural resource sector is an important area of Canada's economy. Of the many natural resources that are mined, uranium mining is centred in northern Saskatchewan. The uranium ore bodies contain many mineral phases beside uranium oxide that need to be disposed of in a responsible fashion. Solid mining waste can be placed in a tailings management facility, which is designed to contain the waste elements and limit interaction with the external environment. To understand how a tailings facility will behave throughout the lifetime of the mining operations that feed the tailings management facility (TMF), and after the site has been decommissioned, it is important to understand the chemistry of the tailings and how they change with time. The JEB tailings management facility located at the McClean Lake operation contains many metals from the separation of uranium oxide, including iron (Fe), arsenic (As), molybdenum (Mo), and uranium (U), among other elements. By comparing the concentration of dissolved species in pore water samples and analysis of the solids in the tailings, coupled with modelling of the behaviour of the tailings, it has been proposed that uranium oxide solids could become soluble in the tailings if they react with carbonate ions to produce soluble uranyl carbonate complexes in the pore water. However, carbonate ions could also react with calcium sulphate (gypsum) and produce calcium carbonate, which would precipitate under the conditions of the tailings facility (near neutral pH). In our most recent collaboration, we have used X-ray microprobe in combination with micro-X-ray absorption near-edge spectroscopy to identify the bulk and trace Ca-bearing species in the TMF, which include gypsum, anhydrite, calcite, aragonite, dolomite, and Ca-bearing clays. With this information in hand, we propose to expand this research to compare how the concentrations of Ca carbonates change with age to the concentrations of solid U minerals, and to relate this to variations in the aqueous bicarbonate and uranyl carbonate complex concentrations in the TMF pore water. This study is necessary to determine if the precipitation of Ca carbonates in the TMF is involved in controlling the aqueous U concentration.

自然资源部门是加拿大经济的重要领域。在开采的许多自然资源中，铀开采以萨斯喀彻温省北部为中心。铀矿体在氧化铀旁边包含许多矿物相，需要以负责任的方式处置。固体采矿废物可以放置在尾矿管理设施中，该设施旨在包含废物元素并限制与外部环境的相互作用。要了解尾矿设施如何在供应尾矿管理设施（TMF）的采矿作业的整个生命周期中，并且在该站点退役后，重要的是要了解尾矿的化学性能以及它们如何随时间变化。位于麦克林湖作战的JEB尾矿管理设施包含许多金属，包括氧化铀（包括铁（Fe），砷（AS），钼（Mo）和铀（U），以及其他元素。通过比较孔隙水样品中溶解物种的浓度并分析尾矿中的固体，再加上尾矿行为的建模，已经提出，如果氧化铀固体在碳酸盐离子中反应以产生可溶性尿布碳酸盐酸碳酸脉碳酸盐酸盐，则可以在尾部中溶于尾矿。但是，碳酸盐离子也可以与硫酸钙（石膏）反应并产生碳酸钙，碳酸钙将在尾矿设施的条件下（接近中性pH）沉淀。在我们最近的合作中，我们使用X射线微探针与微X射线吸收近边光谱相结合，以识别TMF中的大量和痕量含量的含量，其中包括石膏，钙矿石，钙岩，aragonite，aragonite，aragonite，arogonite，dologonite，dolomite，dolomite和ca bearing粘土。借助此信息，我们建议扩展这项研究，以比较Ca碳酸盐的浓度如何随着年龄的增长与固体U矿物质的浓度进行比较，并将其与TMF孔隙水中碳酸氢盐和铀酰碳酸盐复合物浓度的变化联系起来。这项研究对于确定TMF中Ca碳酸盐的沉淀是否参与控制水溶液浓度是否参与。