The initial step towards designing a mine closure plan involves establishing the basic principles. A mine closure plan involves designing a regulatory strategy that will ensure minimal impact on the environment after the mining process. While tailings refer to the fine particles resulting from separation of useful minerals from the ore, waste rock includes the large pieces of ore that need to be extracted to reach the mineral deposit. Geochemical stability is associated with ensuring that chemicals such as acid rock drainage do not form.
A successful mine closure plan requires that the mine operators make efforts to integrate their plans as early as possible. This involves designing the plans even before the mining begins and updating them as required based on new developments at each phase (Lacy & Barnes, 2006). Making plans for these environmental liabilities in advance allows one to make environmentally friendly decisions.
Before coming up with a closure design approach, it is extremely important to conduct geochemical characterization. Mine tailings contain complicated chemical structures that are extremely dangerous for the environment and society; therefore, they should never be considered inert (Cacciuttolo et al., 2023). In order to ensure stability, it is important to analyze the processes causing changes to the geochemistry, such as compaction, chemical loading by pore water fluxes, and biogeochemistry (Cossey et al., 2021).
It is quite clear that dealing with geochemical hazards of tailings requires new and responsible approaches. A modern innovative concept that is becoming increasingly popular includes in-pit disposal of tailings. The idea is to move the fine particulate material back into the exhausted pit as an environmentally friendly option that prevents exposure to air, and thus to oxidation regardless of changing climate conditions (Cacciuttolo & Atencio, 2023).
In relation to waste rock, geochemical stability is achieved by careful placement of materials and cover systems. Initial geochemical investigations of core samples during the mine life cycle can allow mine managers to recognize the potential for acid formation long before mine closure (Lacy & Barnes, 2006). By separating these materials and burying them under impermeable covers, infiltration of water can be avoided, thereby stopping the process of oxidation leading to dangerous leachates from mine waste.
Eventually, geochemical stability requires continued surveillance and adaptive management even years after the cessation of mining operations. Mine closure plans need to consider the interaction between surface water and groundwater at the constructed landforms to ensure that pore water conditions meet stringent requirements (Cossey et al., 2021). Through constant monitoring, abandoned mines can eventually become stable, functioning ecosystems with chemically neutral conditions.
References
Cacciuttolo, C., & Atencio, E. (2023). In-Pit Disposal of Mine Tailings for a Sustainable Mine Closure: A Responsible Alternative to Develop Long-Term Green Mining Solutions. Sustainability, 15(8), 6481. https://doi.org/10.3390/su15086481
Cacciuttolo, C., Cano, D., & Custodio, M. (2023). Socio-Environmental Risks Linked with Mine Tailings Chemical Composition: Promoting Responsible and Safe Mine Tailings Management Considering Copper and Gold Mining Experiences from Chile and Peru. Toxics, 11(5), 462. https://doi.org/10.3390/toxics11050462
Cossey, H. L., Batycky, A. E., Kaminsky, H., & Ulrich, A. C. (2021). Geochemical Stability of Oil Sands Tailings in Mine Closure Landforms. Minerals, 11(8), 830. https://doi.org/10.3390/min11080830
Lacy, H., & Barnes, K. (2006). Tailings Storage Facilities ⎯ Decommissioning Planning is Vital for Successful Closure. Proceedings of the International Conference on Mine Closure, 139-148. https://doi.org/10.36487/acg_repo/605_6
Strelein, K., & Amoah, N. (2012). Long term closure planning for an evolving mine site – a case study of Newmont Boddington Gold Mine in Western Australia. Proceedings of the International Conference on Mine Closure, 251-264. https://doi.org/10.36487/acg_rep/1208_24_amoah
