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Assessing Dilution, Ore Loss, and Profit Differences from Various Hand-Drawn Dig Limits Compared to Optimal Ore-Waste Delineations in Deposits of Variable Heterogeneity

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Abstract

For every blast pattern, zones of unique material types need to be classified before mining. Most material types can be summarized into different kinds of ore and waste. Blocks generated from blasthole assays are too small to be selectively mined so areas with a single material classification meeting the mine’s selective mining unit must be defined. Current industry standard practices are to manually draw ore/waste dig limits but this process is subjective and results in quantities of dilution and ore loss which can be improved upon to enhance the profitability of mining operations. Two weeks production data from a homogeneous Cu porphyry and heterogeneous Manto-type Cu deposit are used to assess the variability in the hand-drawn dig limits for 20 geologists, mining engineers, or ore control specialists and are compared with the optimal ore/waste delineation. The profit for 20 distinct hand-drawn dig limits for the homogeneous mine ranged by 3.7% from $10.5 million to $10.9 million averaging at $10.8 million. The percent range nearly doubled for the more heterogeneous mine at 5.9% from $17.9 million to $19.0 million averaging at $18.6 million. Using the optimal ore waste delineation, the profit increased to $11.0 million (1.9% increase) and $19.3 million (7.0% increase) for the homogeneous and heterogeneous deposits respectively. The natural variability, diggability requirement, and selectivity are identified as the main drivers of ore loss and dilution. Recommendations are provided for reducing the subjectivity in manual hand-drawn dig limits by integrating dig limit optimization algorithms as a tool to assist practitioners.

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Acknowledgements

Isabel Cumming, Jose Arnal, and Stewart Langley are acknowledged for their contributions to the paper.

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  1. Department of Geological Sciences and Geological Engineering, Queen’s University, 36 Union Street, Kingston, ON, K7L 3N6, Canada

    Fouad Faraj

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Faraj, F. Assessing Dilution, Ore Loss, and Profit Differences from Various Hand-Drawn Dig Limits Compared to Optimal Ore-Waste Delineations in Deposits of Variable Heterogeneity. Mining, Metallurgy & Exploration 41, 707–718 (2024). https://doi.org/10.1007/s42461-024-00944-0

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