Authors: Koch, LA; Ladinig, T; Wimmer, M; Wagner, H; Grynienko, M

Open access courtesy of:


Cite As:
Koch, LA, Ladinig, T, Wimmer, M, Wagner, H & Grynienko, M 2022, 'Key issues related to oreflow in raise caving', in Y Potvin (ed.), Caving 2022: Fifth International Conference on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 1397-1410,

Download citation as:   ris   bibtex   endnote   text   Zotero

Oreflow was identified as a key issue for the successful implementation of the novel raise caving (RC) method. Critical excavations for the method are narrow de-stress slots and large production stopes. During extraction, slots and stopes are filled with blasted ore, which supports the excavation walls. To extract the ore, it needs to flow properly towards the drawpoints. Otherwise, voids can form, which serve as space for the hangingwall to cave into and cause dilution. Another critical aspect of oreflow is the avoidance of hang-ups in narrow slots. These can interfere with the predefined draw strategy, can form stress bridges which weaken the de-stress effect and are difficult to remove, especially in higher regions of the slot. Additionally, an even lowering of the bulk material should be achieved to form a free surface on top of the slot and stope. The surface is important to allow a subsequent blast conducted from raises above, which are an essential part of the infrastructure. For a beneficial environment of oreflow, a well-planned mine design and draw strategy are essential. The emphasis in this paper is to highlight the key issues related to oreflow. The key issues, namely avoiding dilution, avoiding hang-ups and the creation of a free surface are individually defined, outlined and described. For this purpose, the oreflow in the large drawbells, which are utilised in raise caving, is analysed further with numerical simulations. The drawbell design is intended to be approached on two sublevels which is beneficial for a complete covering of the stope. Further, such a drawbell design may show positive effects on stability due to a lower amount of infrastructure on each level. The simulations are done by means of the discrete element method (DEM). One part of the work considers the influence of drawbell shapes on the oreflow. It shows that an inclination for the large drawbell of around 60° is advantageous to enlarge the extraction zone. Additionally, the spacing of drawpoints is varied to investigate the effect of proper spacing on the overall flow situation. Thereby, a positive influence of the large drawbell on the interaction between the drawpoints could be shown. The results of the models and outcomes are presented in this paper to highlight the advantages of large drawbells for oreflow.

Keywords: oreflow, raise caving, mine design, discrete element method simulation, drawpoint spacing, drawbell inclination

Beck, DA, Sharrock, G & Capes, G 2011, ‘A coupled DFE-Newtonian cellular automata cave initiation, propagation and induced seismicity,’ 45th U.S. Rock Mechanics/Geomechanics Symposium, OnePetro.
Brown, ET 2007, Block Caving Geomechanics, 2nd edn, Julius Kruttschnitt Mineral Research Centre, The University of Queensland, Brisbane.
Campbell, AD 2020, 'Recovery and flow in cave mining: current knowledge gaps and the role of technology in the future', in J Wesseloo (ed.), UMT 2020: Proceedings of the Second International Conference on Underground Mining Technology, Australian Centre for Geomechanics, Perth, pp. 77–104, 
Castro, R, Hekmat, A, Fuentes, M, Armijo, F & Rodriguez, F 2016, ‘FlowSim – A versatile flow simulation tool to quantify extraction and design alternatives for block caving’, in Proceedings MassMin 2016, pp. 645–652.
Coetzee, CJ, 2016, ‘Calibration of the discrete element method and the effect of particle shape,’ Powder Technology, vol. 297,
pp. 50–70.
Coetzee, CJ. 2019, ‘Particle upscaling: Calibration and validation of the discrete element method,’ Powder Technology, vol. 344, pp. 487–503.
DeGagné, DO & McKinnon, SD 2005 ‘The influence of blasting fragmentation on ore recovery in sublevel cave mines’, in Alaska Rocks 2005, The 40th US Symposium on Rock Mechanics (USRMS), OnePetro.
DeGagné, DO & McKinnon, SD 2006 ‘The influence of cave mass properties on discrete sublevel cave models’, in Golden Rocks 2006, The 41st US Symposium on Rock Mechanics (USRMS), OnePetro.
DEM Solutions Ltd. 2021, EDEM – Course E2020: Introduction to EDEM.
Hancock, WR, Weatherley, DK & Chitombo, GP 2010, 'Large-scale simulations of gravity flow in block caving', in Y Potvin (ed.), Caving 2010: Proceedings of the Second International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 553–566.
Heslop, TG & Laubscher DH 1981, ‘Draw control in caving operations on Southern African chrysotile asbestos mines’, Design and Operation of Caving and Sublevel Stoping Mines, 775 (1981), 774.
Heslop, TG 2010, 'Understanding the flow of caved ore and its influence on ore recoveries and dilution in a block cave', in Y Potvin (ed.), Caving 2010: Proceedings of the Second International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 539–551.
Janelid, I & Kvapil, R 1966, ‘Sublevel caving’, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, vol. 3, no. 2, pp. 129–132.
Kvapil R, 1965 ‘Gravity flow of granular materials in Hoppers and Bins, Part ll, coarse material’, International Journal of Rock Mechanics Mining Science, vol. 2, pp. 277–304.
Ladinig, T, Wagner, H, Bergström, J, Koivisto, M & Wimmer, M 2021, ‘Raise caving – a new cave mining method for mining at great depths’, in Proceedings of the 5th International Future Mining Conference, The Australasian Institute of Mining and Metallurgy, Melbourne, pp. 368–384.
Laubscher, DH 1994, Cave mining – the state of the art, Journal of the Southern African Institute of Mining and Metallurgy, 94(10), pp. 279–293.
Laubscher, DH 2000, Block Caving Manual, prepared for International Caving Study, Julius Kruttschnitt Mineral Research Centre, The University of Queensland, Brisbane.
Laubscher, DH, Guest, A & Jakubec, J 2017, Guidelines on Caving Mining Methods, The Underlying Concepts, W.H. Bryan Mining and Geology Research Centre, The University of Queensland, Brisbane, 282 p.
Lommen, S, Schott, D & Lodewijks, G 2014, ‘DEM speedup: Stiffness effects on behavior of bulk material,’ Particuology, vol. 12, pp. 107–112.
McCormick, R 1968, ‘How wide does a drawpoint draw’,Engineering and Mining Journal, June, pp 106–116.
Sellden, H & Pierce, M 2004, ‘PFC3D modelling of flow behaviour in sublevel caving,’ in Proceedings Massmin 2004, pp. 22–25.
Sharrock, G & Hashim, M 2009, ‘Disturbed gravity flow in block caving’, Proceedings 43rd US Rock Mechanics Symposium and 4th U.S.-Canada Rock Mechanics Symposium, American Rock Mechanics Association, Alexandria.
Sivakugan, N & Widisinghe, S 2013, ‘Stresses within granular materials contained between vertical walls,’ Indian Geotechnical Journal, vol. 43, no. 1, pp. 30–38.
Wimmer, M, Nordqvist, A, Righetti, E, Petropoulos, N & Thurley, MJ 2015, ‘Analysis of rock fragmentation and its effect on gravity flow at the Kiruna sublevel caving mine’, International Symposium on Rock Fragmentation by Blasting, The Australasian Institute of Mining and Metallurgy, pp. 775–791.

© Copyright 2022, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
Please direct any queries or error reports to