However, advancements in mineral processing, stricter environmental regulations, and shifting commodity prices are altering this paradigm. Legacy tailings are increasingly viewed as potential assets capable of generating economic value to fund their own remediation. Reprocessing enables the recovery of minerals previously deemed uneconomic or technically unrecoverable, creating a revenue stream while reducing the volume and toxicity of the remaining waste. This approach shifts operations from a linear “take-make-dispose” model to a circular mining framework, maximizing resource efficiency and enhancing the social license to operate. 3.2 The Engineering Lifecycle: From Liability to Stable Landform The transformation of a legacy tailings deposit from an environmental liability into a viable asset is a complex engineering endeavor. This journey, as visually summarized in Figure 1, is underpinned by a rigorous conceptual and engineering framework that guides the project throughout its lifecycle. The figure illustrates the critical transition from a highrisk liability to a dual-value outcome: a saleable economic asset and a stable, low-risk environmental landform. Figure 1 – The Lifecycle of a Tailings Reprocessing Project 3.3 Critical Factors for Technical Viability 3.3.1 Comprehensive Liability Characterization The initial phase is critical, as all subsequent design decisions depend on a precise understanding of the material. Unlike primary ore bodies, tailings are engineered deposits with unique structural and chemical characteristics. The following should be considered for an adequate Liability Characterization: • Resource Estimation: To attract investment, legacy tailings must be quantified as a mineral resource using systematic sampling and modern estimation techniques to develop a formal block model. • Geotechnical Assessment: A rigorous investigation is paramount to assess the physical stability of the existing Tailings Storage Facility (TSF), particularly for older upstream dams susceptible to static or seismic liquefaction. The program must include extensive in-situ testing—specifically Seismic Cone Penetration Testing (SCPTu) and testing in boreholes and test pits—alongside a laboratory testing program to characterize material properties. Stratigraphic sectioning is
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