Passive treatment of As-contaminated neutral mine drainage from gold mine tailings in cold climate

采矿可能导致砷向自然沃茨释放。在恢复阶段，被动处理是对活跃、关闭和废弃的产生酸性和酸性金属驱油剂的矿场的常见做法。然而，有一个关键的缺乏知识的NMD，特别是在寒冷的气候条件下（低温和高盐度）的处理效率。在寒冷的气候条件下，水的回收和再利用减少了淡水消耗，但增加了污染物负荷盐度和As浓度。这导致了与从盐水和冷水中去除As相关的主要问题。该项目的重点是一个正在开采的矿山和一个废弃45年后恢复的场地的尾矿中的砷-NMD。关于恢复的网站，该项目试图阐明作为保留机制和稳定性内受污染的木材残留物的木材凯迪拉克被动生物过滤器。后者被证明是有效的，超过20年，但负责作为固定化的地球化学过程的识别-定量仍有待确认。这种知识是必要的，以便在Éléonore矿进行可能的复制。该项目的总体目标是产生新的知识和工具，以改善被动治疗的国家导弹防御系统。重点是寒冷气候和高盐度条件。具体目标是：O 1）评价所选天然材料和残渣材料对As的去除效果; O2）评价低温高盐条件下影响因素对As-NMD处理效果的影响; O3）评价20年被动生物滤池的As去除机理和稳定性（Wood Cadillac）; O 4）评估对As-NMD被动处理效率的放大效应（Newmont-Éléonore）; O 5）进行技术经济评估，并提出被动式国家导弹防御系统处理的具体设计标准。所选材料的效率和相关成本的结果将有利于加拿大矿业公司和政府面临类似的污染问题，以改善在寒冷气候中的材料选择，并了解在适应气候变化的背景下，在处理系统的潜在调整。

Mining can entail the release of As towards natural waters. At the rehabilitation stage, passive treatment is common practice for active, closed and abandoned AMD-generating mine sites. However, there is a critical lack of knowledge on NMD, especially on As treatment efficiency in cold climates (low temperature and high salinity). In cold climate, water recycling and reuse reduces freshwater consumption but increases the contaminant load salinity and As concentrations. This leads to major issues related to As removal from saline and cold water. The project focuses on As-NMD in tailings from an active mine and a rehabilitated site, after a 45-year abandonment. With respect to the rehabilitated site, the project attempts to elucidate As retention mechanisms and stability within the contaminated wood residuals of the Wood Cadillac passive biofilter. The latter proved efficient for over 20 years but the identification-quantification of biogeochemical processes responsible for As immobilisation are still to be confirmed. Such knowledge is needed for potential replication on the Éléonore mine. The general objective of the project is to generate novel knowledge and tools to improve the passive treatment of As in NMD. The focus is on cold climate and high salinity conditions. The specific objectives are: O1) Evaluate the efficiency of selected natural and residual materials for As removal; O2) Evaluate the impact of influence factors on the performance of passive As-NMD treatment under low temperature and high salinity; O3) Evaluate As removal mechanisms and stability in a 20-year passive biofilter (Wood Cadillac); O4) Evaluate the upscaling effects on the efficiency of As-NMD passive treatment (Newmont-Éléonore); O5) Conduct a techno-economic assessment and propose specific design criteria for passive As-NMD treatment. Results on the efficiency of selected materials and the associated costs will benefit the Canadian mining companies and governments facing similar As contamination issues to improve the selection of materials in cold climates and to apprehend potential adjustments in the treatment systems in the context of adaptation to climate change.