32 ENABLING SUSTAINABLE MINING THROUGH CEMENTED PASTE BACKFILL OPTIMIZATION: THE CERRO LINDO MINE CASE *A. Bendezú1, L. López1, B. de la Cruz2, J. Ramos2, W. Ramos2, R. Contador3, M.T. BellverBaca4 1Sika MBCC Peru, Peru (*Presenting author: bendezu.alvaro@pe.sika.com) 2Nexa Resources Peru SAA, Cerro Lindo Mine, Peru 3Sika SA Chile, Chile 4Sika Services AG, Switzerland ABSTRACT The mining industry faces increasing pressure to align operational performance with sustainability goals. In underground mines, cemented paste backfill (CPB) is not only a critical ground support method to avoid subsidence, but also an opportunity to decrease mine cycle times, reduce surface tailings disposal, water usage, and overall carbon emissions. This paper presents the Cerro Lindo case study in the broader context of international CPB practice. It describes the collaborative Nexa–Sika approach, summarizes key laboratory and field results and discusses how polymer-enabled paste design in sulfide-rich tailings can become a replicable sustainability lever for underground operations worldwide. At the Cerro Lindo Mine in Peru, a large-scale, polymetallic underground operation owned by Nexa Resources, a comprehensive initiative was launched to optimize the backfill process with a strong focus on efficiency and sustainability. Cerro Lindo operates with two paste plants feeding an underground sublevel stopping operation via pipeline. Historically, the paste mixture relied on high volumes of cement and water to ensure pumpability and strength, impacting both costs and carbon footprint. To address this, the team implemented a targeted optimization program using Sika Stabilizer-MF 701, a high-performance admixture designed to reduce both binder and water demand while maintaining or improving Unconfined Compressive Strength (UCS) and also pumpability over long distances. Through extensive lab testing and full-scale production trials, the following sustainability gains were achieved: • Cement usage reduction of 25% • Water content reduction of 7% • Increased tailings incorporation to underground deposition by 7% • Annual water savings estimated at 30 million liters
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