Repurposing of mine tailings to maximize value recovery and reduce environmental impacts

对包括尾矿在内的固体废物进行负责任的管理是采矿业面临的最大挑战之一。通过改变MT的用途，金属(固体)S(潜在的有害或有价值的)可以从散装材料中分离出来，从而提高从矿产资源中回收有价值的金属，同时将有问题的废物转化为“不起反应的”材料。此外，MT的重新用途是将循环经济原则整合到采矿作业中的一个很好的机会。已开发出矿物分离(环境脱硫-ED)和冶金工艺(化学和生物)以从MT中去除有害和有价值的金属(Loid)S。目前关于MT再利用的知识主要集中在Au、Ni和Co的回收上，表明没有“一刀切”的方法，而且几乎没有与最终残留物的稳定性有关的信息。我研究的长期目标是开发知识和方法，将MT重新用于采矿作业，以减少与其管理相关的环境影响，同时最大限度地回收有价值的元素。这项为期5年的计划致力于通过开发(生物)湿法冶金工艺，在确保最终残留物稳定性的同时，将含有高科技金属(HTM-例如Co和Ni)、贵金属(例如Au)和/或有问题的元素(例如As)的MT的再利用结合在一起。具体目标是：1)评估老化MT再利用过程中涉及的湿法冶金过程和机制的性能；2)评估最终残渣的地球化学稳定性及其在MT再利用战略决策中的整合；3)比较从ED产生的硫化物精矿中回收贵金属的(生物)湿法冶金过程的性能。实现这些目标所使用的方法包括：i)详细的表征(化学、矿物学)，ii)(生物)浸出试验，iii)渗滤液处理以回收有价值的元素并稳定有问题的金属(Loid)S，确保最终残渣(固体和液体)的安全性，以及iv)技术经济分析。将使用参数和统计方法优化(生物)浸出过程的操作条件，以最大限度地增加有价值元素的增溶作用，同时确保最终残渣的稳定性并降低操作成本。这项研究计划将更好地了解(生物)湿法冶金工艺在从MT和ED的硫化物精矿中回收感兴趣的元素(如Co、Ni、Au)方面的优势和局限性，同时将最终残留物对环境的影响降至最低。该计划将培养本科生(4名)和研究生(3名)，从而为加拿大采矿业和研究社区提供该领域亟需的专家。

The responsible management of solid waste, including mine tailings (MT), is one of the most significant challenges in the mining industry. By repurposing MT, metal(loid)s (potentially harmful or valuable) can be separated from the bulk material, thereby enhancing the recovery of valuable metals from mineral resources while converting problematic waste into “unreactive” materials. Moreover, the repurposing of MT represents a great opportunity to integrate the principle of circular economy in mining operations. Mineral separation (environmental desulfurization - ED) and metallurgical processes (chemical and biological) have been developed to remove deleterious and valuable metal(loid)s from MT. Current knowledge on the repurposing of MT, mainly focusing on the recovery of Au, Ni and Co, indicates that there is no “one-size-fits-all” approach, and little information related to the stability of final residues are available. The long-term objective of my research is to develop knowledge and methods to integrate MT repurposing into mining operations to reduce environmental impacts related to their management, while maximizing the recovery of valuable elements. This 5-year program strives to integrate the repurposing of MT containing high-technology metals (HTM - e.g. Co and Ni), precious metals (e.g Au) and/or problematic elements (e.g. As) through the development of (bio-)hydrometallurgical processes to maximize the value of extracted mineral resources while ensuring the stability of final residues. The specific objectives are: 1) evaluate the performance of hydrometallurgical processes and mechanisms involved during the repurposing of aged MT to recover Co and Ni; 2) assess the geochemical stability of final residues and its integration in decision-making for MT repurposing strategies and 3) compare the performance of (bio-)hydrometallurgical processes to recover precious metals from sulfide concentrate emerging from ED. The methodology used to reach these SO will comprise: i) detailed characterization (chemical, mineralogical), ii) (bio-)leaching tests, iii) leachate treatment to recover valuable elements and stabilize problematic metal(loid)s, ensuring the safety of final residues (solid and liquid), and iv) techno-economic analysis. The operating conditions of (bio-)leaching processes will be optimized using both parametric and statistical approaches to maximize the solubilization of valuable elements while ensuring the stability of final residues and reducing operating costs. This research program will provide a better understanding of the advantages and limitations of (bio-)hydrometallurgical processes with respect to the recovery of element of interest (e.g. Co, Ni, Au) from MT and sulfide concentrates from ED, while minimizing environmental impacts of final residues. The program will train undergraduate (4) and graduate (3) students, thus providing the Canadian mining industry and research community with much needed experts in this field.