Shiels, A 2022, 'Unearthing the Black Rock orebody with sublevel caving', in Y Potvin (ed.), Caving 2022: Proceedings of the Fifth International Conference on Block and Sublevel Caving
, Australian Centre for Geomechanics, Perth, pp. 1443-1458, https://doi.org/10.36487/ACG_repo/2205_101
The Black Rock orebody is located at Mount Isa Mines, in northwest Queensland, Australia. Owned and operated by Glencore, the mine has been in operation for almost 100 years. The orebody was last mined as an open cut from 1957 to 1965. It was closed due to two major wall failures and ongoing stability issues one bench short of completion, leaving behind a large quantity of high-grade ore. The remaining orebody is being extracted using the sublevel cave (SLC) mining method. The orebody is located in extensively altered and weak kaolinic shales, with zones of hot and reactive ground. Other challenges include naturally occurring and historic voids, and mining proximity to fixed surface infrastructure. The small SLC has a planned draw of approximately 1.5 million tonnes at 4.5% copper over four years, which commenced in September 2020. This paper discusses the work completed during the project phase and the key learnings during the initial execution phase. This includes geotechnical characterisation, caveability and subsidence assessments, fragmentation testing, cave flow and rock cutter trials, and development of a real-time instrumentation system to monitor surface infrastructure.
Keywords: sublevel caving, weak and poor rock mass, rock cutting, subsidence, cave flow
Beck Engineering 2019, Subsidence impacts from the Black Rock SLC, consultant report.
Berkman, D 1996, Making the Mount Isa Mine 1923 – 1933, The Australasian Institute of Mining and Metallurgy, Melbourne, p. 9 and p. 90.
Campbell, A 2017, Black Rock Open Cut Feasibility Report, Glencore internal report.
Campbell, A 2022, Global Review of Sublevel Caving, PowerPoint presentation, University of Queensland and Mining3, Brisbane.
Edwards, DB 1967, Ground Stability Problems Associated with the Black Rock Open Cut at Mount Isa, Australasian Institute of Mining and Metallurgy, Melbourne.
Hocking, R, Balog, G, Ormerod, T & Pearce, H 2018, ‘Early cave management at the Carrapateena sublevel cave’, in Y Potvin
& J Jakubec (eds), Caving 2018: Proceedings of the Fourth International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 421–432,
Laubscher, DH 2000, ‘Caveability’, A Practical Manual on Block Caving, International Caving Study, and Julius Kruttschnitt Mineral Research Centre, Brisbane.
Perry, F 2019a, Scale Model Experiments on the Black Rock Domains, Glencore internal report.
Perry, F 2019b, Proposed Additional Development Method for Black Rock Cave, Glencore internal report.
PSM 2015, Mount Isa Open Pit Pre-feasibility Study Rock mass Model, consultant report.
Rosengren, KJ 1968, Rock Mechanics at the Black Star Open Cut, Mount Isa, PhD thesis, The Australia National University, Canberra.