ACCELERATING UNDERGROUND DEVELOPMENT THROUGH IN‑CYCLE SHOTCRETE: A CASE STUDY FROM INMACULADA MINE, PERU *L. López-Vinatea1, M. Lozada Ore2, R. Contador3, M.T. Bellver-Baca4 1Sika MBCC Perú, Perú (*Presenting author: lopez.luciano@pe.sika.com) 2 Independent Geomechanics Consultant. Peru (marcolozada.klgs@gmail.com) 3Sika S.A. Chile. Chile 4Sika Services AG. Switzerland ABSTRACT In-cycle shotcrete (ICS) has emerged as a critical enabler of faster and safer underground mine development, particularly in operations with complex geotechnical conditions. As mining projects are pushed to improve productivity, it becomes necessary to reduce cycle times without compromising safety or support effectiveness. This work explores the implementation of ICS at the Inmaculada Mine, a high-altitude epithermal gold-silver deposit in southern Peru. The main challenge at Inmaculada lies in achieving rapid development advance in narrow-vein ore zones hosted by weak volcanic rock, where traditional sequential ground support methods introduce delays in the drill-blast-mucksupport cycle. To address this, an ICS approach was adopted, integrating high-earlystrength, fiber-reinforced shotcrete applied immediately after mucking and scaling, within the same shift. The shotcrete system was engineered with macro-synthetic fibers and alkali-free accelerators to reach a compressive strength of ≥1 MPa within 1 hour of spraying, allowing safe re-entry for continuing the cycle in under 3 hours. This significantly shortened the ground support cycle, improved safety by reducing exposure under unsupported ground (increasing the early-age strength of shotcrete), and enabled continuous development in accordance with the mine’s geotechnical guidelines. A beforeand-after analysis of key performance indicators demonstrates the impact: mine development productivity (linear advance per month) improved by about 8%, total heading cycle time was reduced by approximately 16%, early strength gain exceeded the baseline mix, shotcrete rebound (waste) was lowered, and logistical efficiency of support installation was enhanced. This case study shows how a tailored ICS strategy (including specialized admixtures, fibers, and wet-mix spraying methods) can improve productivity and safety in an underground narrow-vein mining context. The results contribute to the growing body of evidence that ICS, when implemented with the appropriate technology, training, and quality control, can drive substantial performance gains in modern underground mining operations.
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