Vuillier, C 2026, 'Engineering a practical chemical pathway from mine waste to high-value materials', in AB Fourie, G Boggs, J Heyes & M Tibbett (eds), Mine Closure 2026: Proceedings of the 19th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-14, https://doi.org/10.36487/ACG_repo/2615_14
(https://papers.acg.uwa.edu.au/p/2615_14_Vuillier/)
Abstract: Tailings are typically generated in vast volumes, often millions of tonnes, and consist of finely ground mineral particles forming a complex assemblage of oxides, sulphides, hydroxides, silicates, carbonates and other phases. Rather than discrete mineral streams, tailings occur as composite streams in which mineral species are intimately mixed. This complexity underpins the long-term environmental and engineering challenges associated with tailings storage facilities, often persisting well beyond mine closure. Through a different lens, this large mineral mass represents a near-ready secondary raw material. Increasingly, tailings are being considered as a potential resource capable of supporting post-closure value creation, particularly where volumes, mineralogy and proximity to markets align. The author has participated in multiple studies aimed at analysing, separating and repurposing tailings into high-value, high-volume products, including in remote mining contexts. This paper presents a structured early-stage screening methodology to assess the transformation potential of tailings. The approach integrates X-ray diffraction (XRD), X-ray fluorescence (XRF) and quantitative electron microscopy data to define dominant composite mineral streams within a tailings deposit. These streams are used to identify plausible product pathways and associated separation or processing options. Particular attention is given to construction materials such as ceramics, low-carbon concrete and alkali-activated binders (including geopolymers), which may be produced through thermal treatment, acid or alkaline activation, and blending with other industrial byproducts such as fly ash, slag, red mud or delithiated beta spodumene. To reduce reliance on costly and lengthy laboratory testing, the method incorporates a pre-screening step based on stoichiometric and oxide level molecular analysis, accounting for mineral reactivity and atomic bonding affinity. The proposed framework supports early decision-making in tailings repurposing studies by identifying feasible transformation pathways and prioritising testing programs, with the broader aim of reframing tailings from a long-term liability into a potential feedstock for high-volume construction materials and more sustainable post-closure outcomes.