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

采矿可以将砷释放到天然水域。在康复阶段，被动治疗是积极的、关闭的和废弃的产生AMD的矿场的常见做法。然而，关于NMD的知识严重缺乏，特别是在寒冷气候(低温和高盐度)下AS的处理效率方面。在寒冷的气候中，水的循环和再利用减少了淡水的消耗，但增加了污染物负荷盐度和砷的浓度。这导致了与从盐水和冷水中去除砷相关的主要问题。该项目的重点是一个活跃的矿山和一个修复场地的尾矿中的As-NMD，在被废弃45年后。关于修复后的场地，该项目试图阐明木质凯迪拉克被动式生物过滤器在受污染的木材残留物中的保留机制和稳定性。后者在20多年的时间里被证明是有效的，但负责AS固定化的生物地球化学过程的鉴定-量化仍有待确认。要想在埃L金矿上进行潜在的复制，就需要这种知识。该项目的总体目标是产生新的知识和工具，以改进国家导弹防御系统中AS的被动治疗。重点是寒冷的气候和高盐度条件。具体目标是：O1)评估选定的天然和残留材料去除砷的效率；O2)评估影响因素对低温高盐度下被动AS-NMD处理性能的影响；03)评估20年被动生物滤池(Wood Cadillac)中AS-NMD的去除机理和稳定性；O4)评估扩大规模对AS-NMD处理效率的影响(纽蒙特-L)；O5)进行技术经济评估，并提出被动AS-NMD处理的具体设计标准。关于选定材料的效率和相关成本的结果将有利于面临类似污染问题的加拿大矿业公司和政府改进寒冷气候下的材料选择，并了解在适应气候变化的背景下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.