1867 Figure 9. 3D isometric view of post-blast volume survey for stope TJO 017U042U142. These reconciled volumes enabled precise measurement of overbreak in CHF exposures, confirming a reduction from 18% to 10% overall. The survey data supported validation of blast design effectiveness, vibration controls, and wall stability, contributing to the achieved 98% mineral recovery and minimized external dilution. 3. CONCLUSIONS • Implementation of this methodology has delivered measurable outcomes: mineral recovery in secondary stopes reached 98%, overbreak into cemented hydraulic fill was reduced from an initial 18% to 10%, and the economic value added per recovered stope averaged USD 54,000, generating an estimated annual opportunity value of USD 650,000 at current production rates. These results demonstrate that high-recovery pillar extraction can be achieved safely and repeatably in SLS operations bounded by cemented fill, offering a scalable and replicable strategy for similar underground mining projects • Geomechanical characterization and optimized blasting can enable safe, high-recovery stope extraction in underground mining. It aligns with the congress’s theme of Sustainable Infrastructure & Mine Design, showcasing a replicable strategy that balances productivity, stability, and economic value. The integration of blast monitoring tools and design adjustments supports continuous improvement and long-term viability. • Uncontrolled drill hole deviation can increase operating costs by 5–15% per tonne mined, primarily due to additional mucking, backfilling, and remedial blasting requirements. This challenge is particularly pronounced in secondary stope recovery under sublevel stoping, where retreating sequences across multiple levels expose tall (up to 60 m) and narrow (12–15 m) openings, necessitating precise geomechanical stability to prevent instability and excessive dilution. • Given the demonstrated effects of drill hole deviation on overbreak, dilution, and overall recovery efficiency, this factor can significantly influence operating costs. Incorporating the quantified cost of percentage deviation per tonne into cost models enables more accurate economic evaluations and supports scalable improvements in drill-and-blast practices. 4. ACKNOWLEDGEMENTS This work would not have been possible without the strong collaboration of Minera Colquisiri at the María Teresa underground operation. The authors sincerely thank the mine management and operational teams for granting operational access to the site, facilitating safe implementation of the sequential recovery strategy, and providing essential support for the extensive field monitoring required for this work. Special
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