756 installed center launders per row and the size of the upgraded flotation cells are also consistent across these cases. The operating parameters among the four studied retrofits are presented in Table 1. Table 1 – Similarities and consistent results observed among the four case studies FTD FSA Throughput (ktpd) Processed ore Upgraded cells Hudbay Constancia -69 % -42 % 90 Cu-Mo 3/7 TC300 Kennecott Copperton -71 % -38 % 150 Cu-Mo 3/5 TC300 Bagdad -72 % -38 % 90 Cu-Mo 3/6 TC300 Red Chris -63 % -48 % 30 Cu-Au 6/6 TC200 Due to the similar operating conditions of the three retrofits—Constancia, Kennecott Copperton, and Bagdad—the consistent results from metallurgical recovery evaluations are comparable. As summarized in Table 2, at Constancia, copper recovery improved by 0.7% and molybdenum by 1.4%. Kennecott Copperton increased copper recovery by 0.74% and molybdenum by 0.82%, while Bagdad achieved a 0.93% increase in copper recovery and a 3.15% increase in molybdenum recovery, leading to very short payback periods for all the retrofits. The recovery improvements demonstrated in these studies consistently highlight significant enhancements in metallurgical recoveries, providing a strong foundation for expecting similar recovery enhancements in the future. 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
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