Use of fly ash from biomass power plants in mine backfill

Authors: Castilla Flores, A; Valdés, S Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2655_31

Cite As:
Castilla Flores, A & Valdés, S 2026, 'Use of fly ash from biomass power plants in mine backfill', 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. 1-14, https://doi.org/10.36487/ACG_repo/2655_31



Abstract:
Process optimisation is a recurring objective in any industry that aims to remain competitive in the market. In mining, in particular, the cost of operations defines the lifespan of the mine, making process optimisation directly impactful on extending the life of the exploitation mine. Mine backfilling is one of the activities with the greatest economic impact in mining operations. Within the backfilling process, the binder (typically cement) represents the highest operational cost, accounting for up to 50% of the total backfilling expense. As such, there is a continuous drive to find better or more efficient binders or cement additives in order to optimise the mine backfilling process. Traditional cement is expensive and significantly contributes to an increased carbon footprint. Supplementary cementitious materials, such as fly ash and slag, can be incorporated as a sustainable alternative to the binder mix. These materials help improve the performance of the cemented paste, reduce costs, and make the operation more environmentally friendly by revalorising industrial by-products. The case at hand involves the incorporation of fly ash from biomass power plants as an additive to cement in mine backfilling. Fly ash is the residue obtained by electrostatic precipitation or mechanical capture of dust particles present in combustion gases from thermal power stations (whether coal-fired or biomass-based). The use of fly ash from coal-fired power stations as an additive in concrete and even in the production of certain types of cement is standardised and well-established. However, there is currently no standardisation for fly ash derived from biomass power plants. This study presents the feasibility of using this type of fly ash as a cement additive in mine backfilling. It will enable the production of a higher-quality, longer-lasting cemented backfill, reduce operational costs, and contribute to a more stable and environmentally responsible mining operation. The decline of coal-fired power stations and the proliferation of biomass power plants make it necessary to study and work towards the revalorisation of these new residues, reaffirming the commitment to a local circular economy.

Keywords: biomass fly ash, binder reduction, circular economy, backfill process optimisation

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