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Optimal Pitwall Shapes to Increase Financial Return and Decrease Carbon Footprint of Open Pit Mines

Lookup NU author(s): Professor Stefano Utili, Dr Andrea Agosti



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2022, The Author(s). The steepness of the slopes of an open pit mine has a substantial influence on the financial return of the mine. The paper proposes a novel design methodology where overall steeper pitwalls are employed without compromising the safety of the mine. In current design practice, pitwall profiles are often planar in cross-section within each rock layer; i.e., the profile inclination across each layer tends to be constant. Here instead, a new geotechnical software, OptimalSlope, is employed to determine optimal pitwall profiles of depth varying inclination. OptimalSlope seeks the solution of a mathematical optimization problem where the overall steepness of the pitwall, from crest to toe, is maximized for an assigned lithology, geotechnical properties, and factor of safety (FoS). Bench geometries (bench height, face inclination, minimum berm width) are imposed in the optimization as constraints which bind the maximum local inclination of the sought optimal profile together with any other constraints such as geological discontinuities that may influence slope failure. The obtained optimal profiles are always steeper than their planar counterparts (i.e., the planar profiles exhibiting the same FoS) up to 8° depending on rock type and severity of constraints on local inclinations. The design of a copper mine is first carried out employing planar pitwalls, secondly adopting the optimal pitwall profiles determined by OptimalSlope. The adoption of optimal slope profiles leads to a 34% higher net present value and reductions of carbon footprint and energy consumption of 0.17 Mt CO2 eq and 82.5 million MJ respectively due to a 15% reduction of rockwaste volume.

Publication metadata

Author(s): Utili S, Agosti A, Morales N, Valderrama C, Pell R, Albornoz G

Publication type: Article

Publication status: Published

Journal: Mining, Metallurgy and Exploration

Year: 2022

Volume: 39

Pages: 335-355

Print publication date: 01/04/2022

Online publication date: 09/02/2022

Acceptance date: 06/01/2022

Date deposited: 10/03/2022

ISSN (print): 2524-3462

ISSN (electronic): 2524-3470

Publisher: Springer


DOI: 10.1007/s42461-022-00546-8


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Funder referenceFunder name
778360Commission of the European Communities