Morrison, DM 2022, 'Value-production systems for block caving mines', in Y Potvin (ed.), Caving 2022: Fifth International Conference on Block and Sublevel Caving
, Australian Centre for Geomechanics, Perth, pp. 355-368, https://doi.org/10.36487/ACG_repo/2205_24
Block caving mines produce the lowest grade ore in the metal mining industry and more than any other, they must begin to focus on producing ‘value’ rather than tonnes. Block caving involves no primary blasting or backfilling, so the first step in reducing operating cost is to improve coarse ore haulage. Batch
load–haul–dump (LHD) haulage is slow and expensive; it uses six times more fuel (energy) than is required to move the ore (LHD mass is three times the payload plus return). Batch haulage leaves broken ore in active drawpoints untouched 90% of the shift and doubling the speed of the LHD only reduces this to 80%. All other industrial processes moving low-value product to the customer use the cheapest possible technique – a conveying system of some kind. A steel conveying system such as presented here can move ore 80% of the shift, at three times the speed and 20% of the energy of LHDs, around 100 times more effective (8 × 3 / 0.2) than batch haulage. The second step in improving value production is to increase the ore grade. Recent oresorting techniques identifying the most valuable component of the ore stream have been proven effective in surface mines.
Upgrading techniques in underground mines need a process to dispose of the reject material. Removing waste from the ore-flow system is easier in a conveying system amenable to sizing, and inline ore crushing facilitates the removal of waste from the ore stream. Boreholes and raisebore holes can elevate the crushed reject material above the haulage level for storage and disposal in mined out voids. Waste rock can be consumed in cemented backfill or in loose waste rock voids above and behind the production front.
Early removal of negative-value material (zero value, absorbing cost) from the ore-flow has to be balanced against the cost of processing zero-value material through the entire beneficiation process and tailings storage. This is especially important for shaft mines where hoisting waste rock prevents hoisting ore. Even if only 20% of the waste rock can be consumed in mine voids, the implementation underground of low-energy, low-cost, continuous, autonomous ore haulage systems shifts the cost-benefit from high-volume production to high-value production.
Keywords: metal demand, value production, ore haulage, ore upgrading, waste rock diversion, autonomous systems, lower cut-off grade, non-mining technology, cultural change
BloombergNEF 2021, Battery Metals Outlook,
Fitzgerald, J, Clark, CJ, Labrecque, PO & Kalviainen, AM 2020, ‘Kemess underground: project update, production simulation and quadrant crusher layout’, in R Castro, F Báez & K Suzuki (eds), MassMin 2020: Proceedings of the Eighth International Conference & Exhibition on Mass Mining, University of Chile, Santiago, pp. 668–679,
Gleeson, D 2022, ‘Teck’s Carmen de Andecollo operation goes live with Minesense’s shovel-based ore sorting system,’ International Mining, June 2022.
MiHR 2021, Mining Year in Review: National Outlook 2021,
Morrison, D 2017, ‘Meeting the productivity challenge below 2.5 kilometres’, in M Hudyma & Y Potvin (eds), UMT 2017: Proceedings of the First International Conference on Underground Mining Technology, Australian Centre for Geomechanics, Perth, pp. 3–8,
Morrison, D 2019, ‘Electrification to maximize productive capacity,’ Proceedings of The Electric Mine Conference, Toronto, Canada.
Morrison, DM & Labrecque, PO 2020, ‘High-capacity production systems for Block Caving mines’, in R Castro, F Báez & K Suzuki (eds), MassMin 2020: Proceedings of the Eighth International Conference & Exhibition on Mass Mining, University of Chile, Santiago, pp. 703–715,
Morrison, D, Webb, R, Akerman, A & Parsons, H 2015, ‘Mine design impact on operating and capital costs’, in Y Potvin (ed.), Design Methods 2015: Proceedings of the International Seminar on Design Methods in Underground Mining, Australian Centre for Geomechanics, Perth, pp. 433–441,
Shelswell, KJ, Labrecque, PO & Morrison, DM 2018, ‘Increasing productive capacity in block caving mines’, 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. 107–118,
Wood Mackenzie 2019, Global Copper Long-term Outlook Q4 2019, Wood Mackenzie, Edinburgh.