5. Future Directions The roadmap for the industrial deployment of this technology is structured across three horizons: - Short term (1–2 years): Focus will be placed on scaling up from 30-cm minicolumns to 1m, 3-m, and 6-m industrial columns to validate irrigation strategies, thermal gradients, and hydraulic stability. - Medium term (3–5 years): A pilot-scale demonstration scaling this technology from a TRL5 to a TRL7, is required to assess operational robustness under continuous flow, process water recycling, and seasonal variability. This stage will also integrate downstream cobalt purification to establish end-to-end recovery metrics (OPEX/CAPEX, Techno- Economic Analysis (TEA) and Lyfe Cicle Assesment (LCA)). - Long term (5+ years): Industrial-scale implementation as a dedicated valorization facility or as an integrated module within existing tailings management systems, aiming for improved kinetics and automated digital monitoring. 6. Conclusion This study demonstrates that sulfidic fresh tailings from the CS-CL scavenger fraction of the San José de Pucobre flotation plant are a technically viable secondary source of cobalt. The consistent cobalt grades (~950–1100 ppm) and favorable mineralogical characteristics, specifically the high degree of pyrite liberation, support the application of oxidative dissolution processes. The results confirm that microbial bioleaching is a highly effective strategy for cobalt recovery, achieving extraction yields exceeding 90% in both batch systems (day 35) and percolation-based minicolumns (day 120), if inoculation strategies are precisely executed. Among the evaluated protocols, the thermotolerant Kobold B consortium, operating at 45 °C, demonstrated the highest performance. Optimal results were obtained when combined with a pH of 1.5, 80% acid curing pre-treatment, and an inoculum density of 1×10⁷ cells·g⁻¹ applied postcuring. These findings emphasize that the success of tailings bioleaching relies on the synergistic integration of biological activation and physicochemical conditioning. Furthermore, the process exhibited significant potential for polymetallic recovery, with high extraction yields for Ni (94%), Cu (75%), and Fe (61%) under optimized conditions. This multi-metal extraction capability strengthens the value proposition of bioleaching as a circular economy platform for mining waste. The international deposition of the Kobold B consortium at the DSMZ (DSM 35389) and the filing of a PCT patent application underscore the technological maturity and industrial potential of this approach. This research provides robust experimental evidence that bioleaching can transform cobaltbearing tailings from environmental liabilities into strategic mineral resources. By enabling lowenergy, biologically driven recovery of critical metals, the proposed methodology aligns with
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