Table 2 – Recovery improvements over the studied retrofits Cu Mo Hudbay Constancia + 0.70 % + 1.40 % Kennecott Copperton + 0.74 % + 0.82 % Bagdad + 0.93 % + 3.15 % In the specific case of the Constancia Mine, after demonstrating improved metallurgical performance and the associated economic benefits, the site continued advancing optimization initiatives beyond the period analyzed in this study. A comprehensive comparative assessment was later conducted, evaluating operational performance before the implementation of new projects (2020) and after their deployment (2024) (Vallejos et al., 2025). This analysis accounted for variations in ore characteristics as well as the suite of new technologies introduced during the reviewed period, ultimately isolating and quantifying the individual contribution of each factor to overall copper recovery. As part of these improvement projects, additional Center Launders were added completing the installation across the entire rougher circuit and all cells in the cleaner‑scavenger bank. The study reported a copper rougher recovery improvement of 4.2% following the full set of enhancements, with the Center Launder installations specifically contributing a 1.4% increase. When combined with the outcomes of the initial study (Bermudez et al., 2021), the cumulative impact of the Center Launder projects at Constancia can be attributed to an approximate 2.0% uplift in copper recovery. Furthermore, the installation of new Center Launders in the cleaner‑scavenger bank, along with reconfiguration of the cleaning circuit, resulted in a reported 3.2% increase in total cleaner recovery. 4.2 Statistical Considerations and Validity of the Reported Results The performance improvements summarized in this review are supported by rigorous statistical evaluations conducted and reported in the respective original case studies (Bermudez et al., 2021; Bermudez et al., 2022; Liu et al., 2022). In all three cases, the inherent variability typical of industrial flotation operations—such as fluctuations in ore type, head grade, particle size distribution, throughput, and reagent dosage—was explicitly recognized and addressed through comparative and statistically robust evaluation frameworks. Rather than relying on direct absolute before and after comparisons, the authors of the original studies adopted normalized, parallel line methodologies that allowed the upgraded and baseline circuits to be evaluated relative to one another, thereby isolating the effect of the froth launder upgrade. Across the three sites, metallurgical performance was assessed using composite samples collected over extended operating periods (typically 12-hour shift composites over 2+ months or stabilized survey campaigns), with metal recoveries calculated from mass balanced assays. Data screening criteria were applied to exclude non-representative operating conditions, ensuring that the statistical analysis reflected steady-state plant operation. The significance of the observed recovery gains—primarily for copper and molybdenum—was then tested using conventional two sample t-tests, with confidence levels ranging from approximately 90% to greater than 99%, depending on the case and metal considered. These analyses consistently demonstrated that the
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