Critical approaches and methodologies for selecting backfill solutions and plant location for Sociedad Minera El Brocal's Marcapunta underground mine

Authors: Pavlovic, N; Hall, A; Senis, C; Enfantes, M; Gavidia, D; Miniano, P; Calle, CE Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2655_23

Cite As:
Pavlovic, N, Hall, A, Senis, C, Enfantes, M, Gavidia, D, Miniano, P & Calle, CE 2026, 'Critical approaches and methodologies for selecting backfill solutions and plant location for Sociedad Minera El Brocal's Marcapunta underground mine', 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. 1-15, https://doi.org/10.36487/ACG_repo/2655_23



Abstract:
Compañía de Minas Buenaventura S.A.A. retained Responsible Mining Solutions (RMS) to complete a feasibility level design for a paste backfill system for its subsidiary Sociedad Minera El Brocal S.A.A (SMEB or El Brocal). El Brocal is an underground copper mine that consists of 2 primary zones: North and South. Both mining zones are currently being mined by longhole stoping and have 77 Mt of copper ore reserves. A cemented backfill system will be implemented enabling continuous mining while primarily servicing the South mine. A few challenges were encountered such as the underperformance of the paste thickener and inadequate hydraulic fill properties (the surface restrictions for the paste plant infrastructure and limited storage capacity at the tailings storage facility [TSF]). An onsite thickener trial was carried out, showing that the paste thickener can produce thickened tailings at a concentration by weight (Cw) of >70%. Since upgrading the existing hydraulic fill plant was found to be an expensive solution, the approach has been revised: the plant will be modified to produce high‑density fill with a Cw of 75% and a concentration by volume (Cv) of 45%. The testing campaign showed that high-density fill achieved lower strengths than slumpable paste while exceeding the targets required for mining. To mitigate the negative environmental impacts, the paste backfill plant will be installed underground. The primary binder silos and auxiliaries will be installed on the surface at the decline entrance. To ensure a steady thickened tailings production at a Cw of 75%, a density boost circuit will be implemented with a single vacuum disc filter adjacent to the paste thickener. The agitated storage tank will blend a small portion of friable filter cake with the thickened tailings. Concurrently, this circuit alleviates density fluctuations, lowers the risk of pipeline blockage and reduces filtration requirements underground. This is inherently expensive due to underground plant excavation, ventilation, electrical supply, etc.

Keywords: El Brocal, paste, backfill, hydraulic fill, high-density fill

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