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

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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.