Butar Butar, DC, Aquino, NJ, Dzimbanhete, VL & Alakangas, L 2025, 'Mine waste characterisation and understanding metal(loid)s mobility: 
a framework for cost-effective prevention and mine closure', in S Knutsson, AB Fourie & M Tibbett (eds), Mine Closure 2025: Proceedings of the 18th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-10, https://doi.org/10.36487/ACG_repo/2515_59
(https://papers.acg.uwa.edu.au/p/2515_59_Butar/)
Abstract: Most mine closure strategies focus on preventing and treating metal(loid)s leachate (ML) from mine waste but designing effective and cost-efficient mitigation measures at an early stage can significantly improve mine closure outcomes. ML release can originate from multiple sources, including underground or open pit mines, mineral processing plants, waste rock piles and water management systems, which require different mitigation measures due to site-specific water and waste characteristics and prevailing chemical and climatic conditions. Therefore, mine closure approaches should prioritise source control, encompassing not only ore and mine waste but also water quality. Diagnostic assessments are crucial in identifying ML risks and sources as well as predicting potential environmental contamination. These assessments should account for microscale factors, e.g. mineral composition, distribution of trace metals, and mechanical and physical properties of mine waste and environmental factors, including geology, climate and hydrology.
Our study integrates geochemical, mineralogical, and isotopic approaches to identify sources of ML and its mobility from the exploration phase and along the mine value chain. A holistic understanding enables the implementation of early-stage, cost-effective mitigation strategies, such as inhibition and cementation, which can reduce environmental risks and closure costs. Inhibition, or chemical passivation, focuses on secondary precipitation on the reactive mineral surface, preventing it from weathering. Cementation complements inhibition by forming a physical barrier to stabilise mine waste. In our ongoing small-scale column leaching experiments, inhibition and cementation effectively prevent acid mine drainage formation in sulphidic waste rock. Stable isotopes have proven efficient in tracing the mechanisms, transport and mobility of targeted elements, and the effectiveness of preventive techniques. Additionally, radiogenic isotope studies at an iron ore mine in Northern Sweden have provided insights into key weathering processes affecting uranium mobility from the primary contamination source. This article will showcase several case studies and a framework for AMD prevention technologies.

Keywords: metal(loid)s, leaching, mine waste, mine closure, characterisation, prevention, sources, mobility