1013 • Hybrid approaches that combine disciplines, including physical and electrokinetic with chemical approaches. • Heap design and operational considerations also influence recovery and cycle time, such as increasing temperature by the addition of heat, and heap leaching system monitoring and optimization. If heap leaching can be transformed to achieve performance similar to the concentrator plants, in terms of cycle time and recoveries, it can provide a significant benefit of reducing water use, waste, and eliminating tailings. Trend Spotlight: Innovations in copper leaching are entering a transformational phase in achieving industrial scale, backed by mining giants such as BHP, Rio Tinto, Freeport-McMoRan, and Vale Base Metals. This is in the context of record prices for copper, more than $13,000 per tonne, spurring interest in R&D to recover metal, including from waste material. Freeport has indicated that two-thirds of its growth in copper production by 2030 could come from the application of new leaching technologies (Hodgson, 2026). 2.5 Recovery through In-Situ Extraction Recovery of minerals through in-situ extraction will not result in waste and mine tailings that conventional mining and processing produce. In-situ extraction is a method of extracting valuable minerals directly from ore deposits without the need for conventional mining. The key process steps for in-situ might include the following: • Drilling of wells into the ore body, which serves as pathways for the injection of the leaching solution into the mineral deposit. • Once the wells are in place, the leaching solution is pumped through the injection wells into the ore body, where it permeates through the rock and dissolves the target minerals. As the solution moves through the ore, it becomes enriched with the dissolved minerals. • This solution is then pumped back to the surface through recovery wells. At the surface, the mineral-laden solution undergoes processing to separate and recover the valuable minerals. For copper, this typically involves solvent extraction and electrowinning (SX/EW), where the copper is chemically extracted from the solution and then electrically plated onto cathodes to produce pure copper metal. There are several technical challenges to in-situ extraction, including ore body characterization, permeability enhancement, effective lixiviants, solution flow, and effective monitoring and control systems. The current regulatory landscape also does not provide specific guidelines for in-situ extraction in many jurisdictions, and that can further complicate obtaining operational permits. Trend Spotlight: Electrokinetic In-Situ Recovery (EK-ISR) is a relatively new concept, where electric fields drive metal migration and recovery without conventional excavation, eliminating traditional waste streams (Martens et al., 2021). Ekion has tested this technology in Western Australia for extracting metals from tailings and clay-hosted Rare Earth Elements (REEs), demonstrating up to 83% recovery of Heavy Rare Earth Elements (HREEs) in laboratory settings. This technology promises a breakthrough for recovering minerals and is transitioning from academic theory to industry-backed technical trials to validate its technology and economics. 3. CONCLUSION The complete elimination of mine tailings is a difficult endeavor, where many challenges and knowledge gaps remain, especially in dealing with the complexity from multiple commodities, minerals, geographies,
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