Authors: Roa, C; Calderón, J; Castellón, R; Vargas, M

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Roa, C, Calderón, J, Castellón, R & Vargas, M 2020, 'Increasing the reliability of mining plans by predicting geotechnical instabilities with structural control: case study at a BHP mine, northern Chile', in PM Dight (ed.), Proceedings of the 2020 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 763-770,

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Ore extraction at a mine site is carried out according to a mining plan which is essentially a sequence that follows a given throughput and determines how the mining operation itself will be conducted in terms of time and space, in order to maximise the long-term business value. The continuity of a mining plan can be disrupted by unforeseen geotechnical instabilities that can cause accidents, render roads or areas unusable and damage equipment. This can prevent the operation from complying with the mining plan by having to consider alternative haulage roads, having less equipment available for extraction or having to mine unplanned volumes and grades for a period. This paper describes the results of implementing a geotechnical instability prediction process at a BHP site in northern Chile. This tool allows to identify potential geo-referenced instabilities in real and design topographies located in areas scheduled on the short-term mining plan. By identifying potential instabilities, the geotechnical team has been able to find plane, wedge and polyhedral block failures in the design of lower benches, involving from one to four benches. In this case study, a high persistence wedge of 500,000 t and four blocks of 200 to 17,000 t have been identified, and the team has been able to warn the planning and operational department so that they could take preventive mitigation or remediation measures, such as: (1) considering changes in the design to prevent instability formation, (2) removing the instability bench by bench to prevent falling, and (3) recommending the operation team to make changes to the blasting schedule in the area, in order to blast the instability when creating the bench. The geotechnical department has been using these measures to reduce the number of events involving unplanned fall of instabilities, which in turn will limit operational disruptions that cause delays in the mining plan and will improve the chances of carrying out the plan as scheduled.

Keywords: instabilities prediction, geolocalised, mining plan, operational continuity

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