Investigating the biophysical challenges associated with mine closure in different mining methods

Authors: Fathi Salmi, E; Costa Picorelli, R; Sellers, EJ Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2215_38

Cite As:
Fathi Salmi, E, Costa Picorelli, R & Sellers, EJ 2022, 'Investigating the biophysical challenges associated with mine closure in different mining methods', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: Proceedings of the 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 539-556, https://doi.org/10.36487/ACG_repo/2215_38



Abstract:
Closure issues vary depending on the mining method, creating different biophysical challenges on the surface and underground. In turn, mining methods depend mainly on the geology of the ore deposit, which itself is defined by regional characteristics, such as morphology and local tectonics, etc. The closure is an important factor in developing and planning new mines but is often subordinate to other factors. The mining method is often selected based on pre-feasibility studies and there is limited ability to change the operational characteristics once implemented. If the ability to close the mine, re-use the landscape and contribute to the community and post-mining economy is to become driving factors in the selection of the mining methods and subsequent mine operations, then they should also be carefully considered in early decision-making. A few new mining methods have been proposed for zero-entry and invisible mining that leave waste in place and reduce ore movement. Since these methods require the use of alternative technologies, such as robotics for automation, leaching, and efficient cutting, they will introduce a different set of biophysical issues that will affect the closure and post-mining land use. The potential benefits may be outweighed by their risks, or they may introduce a new set of opportunities for closure at a lower cost and with minimal biophysical risks. This study has, therefore, aimed to compare the biophysical closure impacts of conventional and novel mining methods and to identify if the new mining methods, especially in-place mining, support a business case for closure that enables and motivates the industry to adopt these new mining methods. We identify, compare, and contrast biophysical impacts on post-mining land use for in-place mining methods relative to more traditional mining methods using desktop studies, workshops, and interviews with member company representatives. The study also identifies opportunities to use new mining methods that enable alternative closure options. The study develops and uses a comparative matrix that compares the biophysical impacts of novel mining approaches with the more traditional mining methods (e.g., open pit mining, underground stope mining, and cave mining). The study highlights the current problems, identifies transformational opportunities, and determines future activities that could enable mining methods with improved closure outcomes. The biophysical impacts of different methods should be compared quantitatively, although the current reference site approach has flaws. The use of the rock engineering system enabled quantitative analysis of the survey data, though highlighted that many experts are unaware of the biophysical impacts at closure. The findings also show that the new mining methods are expected to modify and reduce the closure issues relative to the conventional mining methods, which often require large open pits, voids underground, and large tailings footprints. Further investigation is needed to further develop the novel mining methods and to evaluate the applicability of the methods for local small operations as the transition point to full-scale adoption.

Keywords: biophysical impacts, new mining methods, open pit mining, underground stope mining, and cave mining

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