A review on the geotechnical design and optimisation of ultra-long ore passes for deep mass mining

Abstract

Enhancing mine energy efficiency and productivity necessitates the implementation of longer ore passes, exceeding 300 m, to optimise material transport in underground mass mining. This research has revealed sporadic historical use of extremely long ore passes, stretching beyond 500 m and reaching up to 650–700 m, in both surface and underground settings. However, the scarcity of available data related to the primary engineering, geological, and geotechnical risks associated with the design, implementation, operation, and maintenance of long ore passes implies an urgent need for research into strategies to mitigate uncertainties in the design and optimisation of these passes. A comprehensive gap analysis from available ore pass projects worldwide, compiling various geological and geotechnical parameters affecting the ore passes’ design and optimisation, identifies new techniques for designing these critical rock structures, highlights deficiencies in current methodologies, and shows areas for enhancement through expert elicitation techniques and risk assessment methods. Key utilisation scenarios for ore passes exceeding 300 m in length were also identified within the research and categorised into the design phase, emphasising stability, inclination, and gate loading, and the construction phase, including drilling, blasting, raiseboring, and support and lining, and the operational phase, encompassing flow dynamics, hang-ups, and ore fragmentation consequences. Insights gleaned from this comprehensive literature review and gap analysis provide a robust foundation for geotechnical engineers involved in the design of long and ultra-long ore passes for deep mass mining. These findings can empower engineers by enabling them to proactively anticipate, effectively respond to, and continually learn from the challenges inherent in the design, construction, operation, and maintenance of ultra-long and long ore passes. Further research is needed to facilitate energy-efficient material transfer in deep mass mining, including proper design and implementation of passes in uncertain geological conditions. This includes techniques for investigating the long-term stability of ore passes, enhancing the understanding of the risk of structural failure, improving characterisation of rock fragments, investigating flow dynamics, identifying better liner materials, methods for determining optimal pass placement, improving surveying and monitoring techniques, quantifying the rheological behaviour of muck and wet muck for flowability assessment, assessing the impact of mining-induced stresses on the stability of long ore passes, and developing safer and more efficient techniques for the mitigation and recovery of hang-ups.