Benchmarking raise mining with large stoping operations

In southern Norway, a REE deposit is currently under exploration. To meet stringent requirements and protect the environment and local communities, any mining operation must be conducted entirely underground, with no subsidence or impact on the nearby waterbody. Since those requirements are a significant cost factor, a new mining method, raise mining, was developed that involves creating large stopes and thereby ensures high production rates and productivity. To assess the advantages, disadvantages and trade-offs of raise mining in comparison to alternative methods, a literature review on ten operational criteria ¿ Production, Scalability, Selectivity, Flexibility, Transport, Automation, Infrastructure, Backfill, Geotechnics, and Costs ¿ was conducted. Those criteria are further divided into 35 factors, each with defined metrics, enabling objective comparisons between raise mining and the eligible alternative mining methods sublevel open stoping, cut and fill mining, and shrinkage stoping. For the benchmarking, a framework was developed in the style of a guideline for consistent treatment of uncertainties (cf. Mastrandrea et al., 2010). This includes a scale for evidence, that describes the type, amount, quality and consistency of data and literature on the specific factor for the respective mining method, a scale for agreement, which reflects the degree of consensus among the sources, and a scale for rating, that assesses each method's inherent performance and its effectiveness given the deposit's characteristics. In the rating system, qualitative scales with indicators are employed. This approach sometimes fails to capture the quantitative differences between mining methods but aims to reflect their relative strengths and weaknesses adequately. To address these limitations, implementing a weighted scoring system could provide more accurate comparisons and better represent the magnitude of differences between methods. The results can be used as a basis for further investigation and the mining method selection process.