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

对包括尾矿（MT）在内的固体废物进行负责任的管理是采矿业面临的最重大挑战之一。通过重新利用MT，可以从散装材料中分离出（潜在有害或有价值的）金属，从而提高从矿物资源中回收有价值的金属，同时将有问题的废物转化为“非反应性”材料。此外，MT的再利用是将循环经济原则融入采矿作业的绝佳机会。矿物分离（环境脱硫-艾德）和冶金工艺（化学和生物）已被开发用于从MT中去除有害和有价值的金属（类）。目前关于MT再利用的知识主要集中在Au、Ni和Co的回收上，这表明没有“一刀切”的办法，关于最终残留物稳定性的信息很少。我的研究的长期目标是开发知识和方法，将MT再利用整合到采矿作业中，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。这个为期5年的计划致力于通过开发（生物）湿法冶金工艺，整合含有高科技金属（HTM -如Co和Ni）、贵金属（如Au）和/或有问题元素（如As）的MT的再利用，以最大限度地提高所提取矿产资源的价值，同时确保最终残留物的稳定性。具体目标是：1）评估湿法冶金工艺的性能和在将老化的MT再利用以回收Co和Ni期间所涉及的机制; 2）评估最终残留物的地球化学稳定性及其在MT再利用策略决策中的整合，3）比较（生物）湿法冶金工艺，从电火花加工产生的硫化物精矿中回收贵金属。（一）详细的表征（化学、矿物学）;（二）（生物）沥滤试验;（三）沥滤处理，以回收有价值的元素并稳定有问题的金属（类金属），确保最终残留物（固体和液体）的安全;以及（四）技术经济分析。将使用参数和统计方法优化（生物）浸提工艺的操作条件，以最大限度地溶解有价值的元素，同时确保最终残留物的稳定性并降低运营成本。本研究计划将提供一个更好的理解（生物）湿法冶金过程的优势和局限性方面的回收感兴趣的元素（如钴，镍，Au）从MT和硫化物精矿从艾德，同时尽量减少最终残留物的环境影响。该计划将培养本科（4）和研究生（3）的学生，从而提供加拿大矿业和研究界急需的专家在这一领域。

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.