Utilisation of an engineering calcium aluminosilicate binder for cemented paste backfill with challenging mineralogy

Authors: Romaniuk, N; McFarlane, L; Hariharan, N Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2655_08

Cite As:
Romaniuk, N, McFarlane, L & Hariharan, N 2026, 'Utilisation of an engineering calcium aluminosilicate binder for cemented paste backfill with challenging mineralogy', in AB Fourie, M Horta, M Oliveira & S Wilson (eds), Paste 2026: Proceedings of the 28th International Conference on Paste, Thickened and Filtered Tailings, Australian Centre for Geomechanics, Perth, pp. 1-13, https://doi.org/10.36487/ACG_repo/2655_08



Abstract:
Buoyed by high gold prices and demand for critical minerals like copper, miners are increasingly exploiting underground reserves, often with decreasing ore quality. In underground mining, the utilisation of mine tailings in cemented paste backfill (CPB) is key to maximising extraction and improving economics, while reducing external tailings footprints, providing social license to operate. As new ore bodies are exploited, resulting tailings possess challenging mineralogy that can contain considerable amounts of iron sulphides and/or expansive phyllosilicate minerals, which present significant challenges for CPB operations. Portland cements, such as general use limestone cement, lack the physical and chemical characteristics necessary to achieve strength targets in CPB systems containing elevated sulphate or phyllosilicate minerals, thus forcing operators to rely on alternative binders, such as primarily slag cements, to manage binder cost. The production of ground granulated blast furnace slag (GGBFS), key to producing slag cements, has plateaued and is set to decline as the blast furnaces that produce these slags are replaced with lower carbon intensity electric arc furnaces. Lack of GGBFS poses an existential risk for many CPB operations and necessitates the development of new binder alternatives. This study builds on previous investigations into the development of an engineered calcium aluminosilicate (CAS) binder designed to provide comparable strengths to slag cements in these challenging CPB systems, while maintaining a low embodied carbon footprint and a local supply chain. Key developments further demonstrate beneficial interactions with admixtures, such as plasticisers, commonly employed in challenging CPB operations.

Keywords: cemented paste backfill, pozzolanic reactions, low carbon, slag alternative, rheology, uniaxial compressive strength

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