4.3.2 Dynamic oxidative processes (Ceibo staged oxidation family) The Ceibo patent family (Cartagena Fagerström et al., US 12,435,389 B2; WO2024/258924; Román Espinoza et al., WO2025/144618 A1) elaborates on the nitrate concept through a "Dynamic Oxidation Process" (DOP): staged low-flow irrigations with reactive liquid mixtures at controlled high ORP progressively transform the chalcopyrite surface before a higherflow main leach integrated with SX–EW. Key disclosed parameters include low-flow irrigation at ~0.5–5 L/h·m² during oxidative conditioning versus ~5–12 L/h·m² during leaching; nitrate at ~0.02–0.4 M with sulfuric acid ~0.05–1 M; and ORP targeting >770 mV vs SHE (~>570 mV vs Ag/AgCl), with some embodiments extending to ~1000 mV vs SHE, controlled via H2O2, ozonated micro/nanobubbles, or oxygen injection. The transpassive potential regime appears to be used to push dissolution through and beyond the passive zone rather than to dismantle it chemically. The patents also describe metathesis of chalcopyrite to more readily leached secondary phases such as covellite via CuFeS₂ + Cu²⁺ → 2CuS + Fe²⁺. Under the high-copper, acidic, and strongly oxidizing conditions of the DOP stages, this cation-exchange reaction may represent a meaningful pathway to secondary sulfide intermediates that dissolve more readily in the main leach stage. Under conditions where sulfur is oxidized to sulfate, accumulation of Rfilm from sulfur deposits is suppressed, and the primary kinetic lever in Figure 3 is Rj(E) and Rct via the high driving force of the transpassive potential. 4.4 Elevated-temperature bio-heap leaching: the Nuton approach Nuton, a Rio Tinto venture, is a commercially deployed elevated-temperature bio-heap leaching system for primary copper sulfide ores. The technology integrates naturally occurring microorganisms cultivated in proprietary bioreactors, heap engineering, aeration management, and digital tools (Rio Tinto, 2025; Nuton, 2023). In late 2025, Nuton achieved first copper production at the Johnson Camp Mine in Arizona, a partnership with Gunnison Copper Corp., targeting approximately 30,000 tonnes of refined copper over a four-year demonstration period: the first industrial-scale validation of this technology (Rio Tinto, 2025). At the core, Nuton appears to be an elevated-temperature bioleaching process. As described publicly by Nuton's venture lead, the elevated temperatures are generated by bacterially driven sulfide oxidation, without the need for external heating, and under the right thermochemical conditions this delivers peak copper recovery from primary sulfides (Burley, quoted in International Mining, 2022). The microbes accelerate sulfide mineral oxidation, generate heat, and enable copper to dissolve into leach solution that is processed via conventional SX–EW. The NI 43-101 technical report for the Johnson Camp Mine confirms primary sulfide copper mineralization dominated by chalcopyrite, with column testing indicating copper leaching extractions up to ~84% under Nuton-related test conditions, and a total copper recovery estimate of 50.1% across all ore types including run-of-mine material (Gunnison Copper Corp., NI 43-101 Technical Report, 2025). Patent literature assigned to Rio Tinto entities discloses a range of potential process elements including silver catalysis (Brown et al., 2020; Hackl et al., 2020), pyrite addition during agglomeration (Fennel et al., 2022; Burley et al., 2022), and nitrogen-containing organic
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