Resource potential of mine wastes: A conventional and sustainable perspective on a case study tailings mining project

Mine wastes such as tailings contain minerals that can be valorised. However, their resource potential remains widely misjudged because of non-standardised assessment and classification methods. The current United Nations Framework Classification for Resources (UNFC) concept is tested for its applicability to metalliferous tailings mining projects from a private mining company's perspective with economic focus on a scoping study level. For the case study tailings storage facility (TSF) Cabeco do Piao (Portugal), a rehabilitation scenario, and two resource recovery scenarios with low and high degree of tailings valorisation are defined and evaluated. A risk assessment shows that actions are necessary to protect human health and the environment. Material flows are modelled and a discounted cash flow analysis, under consideration of mineral price uncertainty, indicates the project's economic viability. The application of the UNFC principles exemplifies that they cover a broad range of aspects in contrast to the conventional classification principles of the Committee for Mineral Reserves International Reporting Standards (CRIRSCO) which focus on techno-economic aspects: TSF rehabilitation is identified as a necessary base case and positive socio-environmental impacts are prioritised. However, the resource recovery scenarios cannot be differentiated with the current UNFC concept. The evaluation reveals the necessity for a stronger user guidance in the assessment and classification process. Additionally, a more detailed subcategorisation is required to identify a project's benefits and barriers, particularly in social and environmental domains. These aspects are essential for the further development of the UNFC concept to achieve its full potential. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The research tested the applicability of the UNFC concept to metalliferous tailings mining projects, focusing on economic aspects. Different scenarios for resource recovery and rehabilitation of the tailings storage facility were defined and evaluated, with a risk assessment highlighting the need for actions to protect human health and the environment. The study also pointed out the necessity for stronger user guidance and more detailed subcategorisation in the assessment and classification process to fully realize the potential of the UNFC concept.