1901 and 700 m. A comparison of the different drift lengths needed for options V1 to V6 is shown in Figure 7. A 3D visualization of the mine’s developments and stopes after a Life of Mine of approx. 20 years is given in Figure 8. Figure 8 – Visualization of the mine layout including drifts and stopes; left side: visualization of the mine’s infrastructure consisting of the main ramp and decline (red color), primary developments on the three main levels (orange color) connected by four ventilation shafts (blue color), one gravity shaft (grey color) and secondary and tertiary development (blue color) at the access and haulage levels; right side: mined and backfilled stopes are shown. 7. CONCLUSIONS Raise stoping with cemented tailings backfill is the preferred concept for Fen, combining low preproduction development, high potential for mechanization/automation and remote operation, and markedly reduced personnel exposure to rockfall and radiation hazards. The method provides high operational adaptability, as stope geometry can be selected after development based on observed ground conditions and ore quality while keeping raise centrepoints fixed on a 45 m grid. Panel design options allow a trade-off between recovery and stability: full-extraction stopes (circular/hexagonal) achieve higher 2D recovery (~47– 52%) than honeycomb layouts (~36%) that introduce panel pillars for increased geomechanical robustness. The main technical constraint is backfill strength development: cemented paste-fill typically requires 12–24 months to reach target strength, imposing strict sequencing. Under a 24-month curing assumption, a 12-stope panel requires ~6 years, so multiple panels must operate in parallel to sustain 5 Mt/y, improving schedule smoothness but demanding disciplined backfill logistics and quality control. By contrast, LHOS remains feasible but is less attractive operationally due to high development demand, reliance on parallel horizons to meet 5 Mt/y, and increased support requirements in barrier-pillar drifts. ACKNOWLEDGEMENTS This study has been supported by the European Union’s Horizon Europe Research and Innovation Program through the project REESOURCE Project under Grant Agreement number 101138460. REFERENCES Dahlgren, S. (2006). Fenvulkanen In: Ramberg, I. B., Bryhni, I. & Nøttvedt, A. (eds.) Landet blir til: Norges geologi, 146. Itasca (2023): FLAC3D. Version 7.0: Itasca. Online verfügbar unter http://docs.itascacg.com/flac3d700/contents.html.
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