Water recirculation rates in the dry stack cases (Cases B and D) exceeded 88%, confirming the theoretical expectation that filtered tailings configurations eliminate the majority of process water from the TSF circuit. In the paste cases (Cases A and C), recirculation rates of 74–78% represent a significant improvement over the 45–55% recirculation rates typical of conventional slurry TSF configurations (Jewell & Fourie, 2006). Dewatering circuit energy reductions of 12–21% were achieved through the combination of thickener optimization (adaptive flocculant dosing via Metso Metrics), filter press cycle optimization, and reduced tailings pumping flows. TSF footprint reductions reflect the increased density at deposition combined with improved geotechnical stability margins that allow steeper stack slopes in filtered configurations. The projected life extensions—3–8 years beyond the pre-MT4.0 design lives—result from the combination of reduced annual tailings volume deposited (due to denser packing) and improved TSF stability that reduces the required safety buffer capacity. These life extensions have significant financial value: in the two largest operations (Cases A and B), deferring TSF expansion by 4–8 years represents a net present value saving of USD 35–80 million at prevailing expansion capital costs and discount rates (Metso, 2024a). Metso Technology MT4.0 Function Key Performance Contribution Applicable Stage High-Rate & Paste Thickeners Water recovery from tailings slurry; density conditioning for transport Underflow 60–75% solids; recirculation 74– 78% Concentrator — TSF interface Larox® Pressure Filter / VPA Filter Press Dry stack filtration; elimination of free water from TSF Moisture <15%; recirculation 88–91% Dry stack TSF feed preparation PSI 500i Particle Size Analyzer Real-time grind PSD monitoring; grinding circuit closed-loop control Stable grind target; optimized liberation for flotation and dewatering Grinding circuit Courier® On-Stream Analyzer Continuous multielement assay; early detection of ore type shifts Proactive reagent adjustment; stable tailings chemistry Flotation — tailings streams ViscoSense® Rheology Analyzer Real-time viscosity and yield stress measurement in tailings lines Adaptive pump and thickener control; reduced blockage risk Tailings pumping system Metso Metrics Platform Digital twin; remote monitoring; predictive analytics; expert support Anomaly detection; proactive optimization; reduced site visits Plant-wide — remote operations HSC Sim Process Simulation Life-of-mine energy and water modeling; equipment sizing optimization Design-phase energy savings; avoidance of oversized infrastructure Feasibility — detailed design Table 2 – Metso technology portfolio mapped to Mine to Tailing 4.0 functions. Sources: Metso (2022a, 2022b, 2023a, 2023b, 2024a). 8. DISCUSSION 8.1 Theoretical and Practical Contributions
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