Beck, D, Hancock, E, Steffen, S & Lloyd, J 2024, 'Major causes of ore loss in large block and panel caves', in Daniel Johansson & Håkan Schunnesson (eds), MassMin 2024: Proceedings of the International Conference & Exhibition on Mass Mining, Luleå University of Technology, Luleå, pp. 579-593.
(https://papers.acg.uwa.edu.au/p/2435_D-09/)
Abstract: Successful ore recovery in large block and panel caves is dependent on minimising underbreak, overcoming stalling, managing large scale funnel flow and rilling and designing to avoid collapse. The role of simulation in cave management is to identify potential for these problems at all stages of the planning cycle. Analysis also establishes a baseline for comparison of the cave shape and flow measurements during execution, to assist in identifying when an adverse scenario may be evolving so the draw-undercut schedule and strategy can be modified. Ideally, analysis of cave flow measurements and cave constrained flow simulation results will proceed as part of a rapid decision cycle, constantly updating the extraction sequence and draw plan to best achieve the ideal sequence of intermediate cave shapes to minimise hazard and ore loss. 

Back analysis of cave marker movements and cave performance of a number of mines using coupled Finite Element, Position Based Dynamics modelling (LR4-FS4) has identified some gaps in the conventional cave measurement-analysis-decision cycles. The performance forecasts from many mines have assumed simple vertical mixing models for flow, or not accounted for intermediate cave shapes. But to be sufficient, the analysis must be able to simulate mechanisms of adverse flow and must account for the sequence of cave shapes, with sufficient cave flow monitoring coverage and resolution to confirm the cave flow is as planned and show adverse scenarios or signs they are emerging.  

This paper discusses observations of the major flow and shape related mechanisms of ore loss that drive cave under performance and the practical implications of these observations for cave studies, cave management and cave performance forecasting and reporting.