MINERÍA la mejor puerta de acceso al sector minero EDICIÓN 578 / NOVIEMBRE 2025 89 Figure 2 illustrates it is not easy to visually differentiate barren core (<0.05% Cu) from low-grade (weakly mineralized) core (0.05 - 0.25% Cu). Visual observations indicate that assigning a 0.0% Cu grade to unassayed core carries a substantial risk to the DL model as the algorithm is likely to determine an area is barren to economic mineralization due to the predominance of unassayed core. Results DL Model Evaluation It is necessary to create an accurate method by which to test and evaluate DL models against one another to establish the value of incorporating lithology logs for each deposit into the DL modelling process. Overview As the Atacama Kozan is an underground operation it was best to evaluate the quality of each model by their forward-facing precision and recall; the copper DL model is created using data collected prior to 2021 and compared against drilling data collected in 2021 - 2022. To ensure enough data was used to evaluate the copper DL model, two years of data collection were used for comparison instead of one. The models were evaluated based on precision and recall. Precision is the percentage of blocks predicted as economic high-grade (HG) that are reconciled as HG in forward-facing diamond and RC drilling. It tracks the frequency of false occurrences, as in incidences when a HG block or vein projected in the mine plan reconciles as waste. Precision can alternatively be interpreted as the false positive rate, denoted in Figure 3a. A model with a precision of 100% reconciles HG in all blocks predicted as HG while a model with a precision of 0% exclusively reconciles waste inside of HG blocks Recall is the percentage of reconciled HG that is predicted as HG. It tracks the frequency of false negative occurrences, as in occurrences that veins exist, but were missed by the resource model. Recall can alternatively be interpreted as the missed mineralization rate, denoted in Figure 3b. A model with a recall of 100% misses no mineralization while a model with a recall of 0% does not predict any block drilled as high-grade. The objective of the resource model is to model additional copper mineralization that can be incorporated into the resource definition drilling targeting program, without lowering the sensitivity of HG misclassification beyond a minimum threshold (i.e. cutoff grade). Copper Mine Figure 3a and Figure 3b illustrate false positive and missed mineralization rates, respectively, between different DL models. The 2021 Kriging model is also included which is created using ordinary Kriging in mineralization domains. The elevated forward-facing false positive rate in reconciliation is common in resource definition drilling of underground base metals and precious metals deposits. This is because resource definition drilling tends to be drilled in areas with less data than grade-controlled regions in underground deposits, which tend to have a higher cut-off grade. This invariably results in less HG blocks defined as a whole, when compared to waste. The false positive rate generally decreases to <50% for grade control drilling. Furthermore, for expanding the resource, the sensitivity towards finding more economic ore should be greater than the sensitivity to finding waste predicted as ore. For the D(Cu, ZFCU) ~ D(Cu, ZFCU) model, it has the lowest missed mineralization rate of 71.8% compared to the Kriging model rate of 83.2%, whereas the D(Cu) ~ D(Cu) model is 82.8%. The D(Cu, FCU) ~ D(Cu, ZFCU) model missed mineralization rate of 71.8% indicates that 28.2% of material reconciled as HG in 2021 - 2022 was predicted as HG by the DL model using pre-2021 data. Similarly, the Kriging model missed mineralization rate of 83.2% indicates that 16.8% of material reconciled as HG in 2023 was predicted as HG by the Kriging model using pre-2021 data. This translates to a 1.67x increase in reOwn elaboration based on Stratum AI data. Figure 6. Target 16: Historical Drilling vs Drill Plan. Own elaboration based on Stratum AI data. Figure 7. Target 65: Historical Drilling vs Drill Plan.
RkJQdWJsaXNoZXIy MTM0Mzk2