Rio Tinto Kennecott manufactured paste backfill: initial concept to pilot testing

Authors: Roberge, J-L; Tomini, E; Chaudoin, B; Moran, K; McGinn, C; Jovcic, N; Timballah, S Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2655_27

Cite As:
Roberge, J-L, Tomini, E, Chaudoin, B, Moran, K, McGinn, C, Jovcic, N & Timballah, S 2026, 'Rio Tinto Kennecott manufactured paste backfill: initial concept to pilot testing', 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. 1-10, https://doi.org/10.36487/ACG_repo/2655_27



Abstract:
This paper explores the development of a novel process which creates a paste backfill product from crushed waste rock in an open pit mining operation transitioning to underground. Rio Tinto conducted an initial feasibility study for a paste backfill plant that would take tailings from the Copperton Concentrator to produce a paste backfill product for the Kennecott Underground Orebodies located in the northern wall of the Bingham Canyon Pit, Salt Lake City, Utah. After a design review process which focused on capital savings, the concept of a paste backfill produced by crushing the open pit waste rock emerged. This design allows for the elimination of a desliming and thickening plant near Copperton Concentrator, as well as a roughly 8 km pipeline. This results in capital savings, as well as eliminating the environmental risk around a surface tailings pipeline. Although similar concepts have been studied or implemented previously, they typically relied on a partial tailings stream or grinding to produce the fines sufficient for a paste. This paper will focus on a case study for a paste backfill design utilising a simple crushing circuit able to generate a product with a suitable particle size distribution to form a stable paste, sourced from open pit waste rock. This case study will provide information on the initial index testing on samples from an existing crusher and an extensive testing program supporting conceptual ideas around waste rock mineralogy, particle size distribution, rheology and strength gain potential. Ultimately, the testing program culminated in the establishment of a pilot level testing campaign utilising production-scale crushing equipment which provided critical insight into the design. The engineering design addressed several key factors including technical scalability, material handling, equipment design/selection, operability and cost considerations. This phase of the engineering study can be directly compared to the more conventional paste backfill.

Keywords: paste backfill, open pit waste rock, crushing

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