Journal Article10.1007/S11081-017-9361-6
A stochastic optimization formulation for the transition from open pit to underground mining
TL;DR: In this paper, an approach to determine an optimal transition depth at which a mine should transition from open pit to underground mining, based on managing technical risk, is presented, where the value of a set of candidate transition depths is calculated by optimizing the production schedules for each depth.
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Abstract: As open pit mining of a mineral deposit deepens, the cost of extraction may increase up to a threshold where transitioning to mining through underground methods is more profitable. This paper provides an approach to determine an optimal depth at which a mine should transition from open pit to underground mining, based on managing technical risk. The value of a set of candidate transition depths is calculated by optimizing the production schedules for each depth’s unique open pit and underground operations which provide yearly discounted cash flow projections. By considering the sum of the open pit and underground mining portion’s value, the most profitable candidate transition depth is identified. The optimization model presented is based on a stochastic integer program that integrates geological uncertainty and manages technical risk. The proposed approach is tested on a gold deposit. Results show the benefits of managing geological uncertainty in long-term strategic decision-making frameworks. Additionally, the stochastic result produces a 9% net present value increase over a similar deterministic formulation. The risk-managing stochastic framework also produces operational schedules that reduce a mining project`s susceptibility to geological risk. This work aims to approve on previous attempts to solve this problem by jointly considering geological uncertainty and describing the optimal transition depth effectively in 3-dimensions.
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Citations
A stochastic mathematical model for determination of transition time in the non-simultaneous case of surface and underground mining
TL;DR: The solutions proposed for the transition problem have a heuristic basis and follow a similar process by use of the cash flow solution introduced by Nilsson (1982), but the main drawback is their complete dependence on the optimization algorithms of surface and underground mining.
A Set of Classified Integer Programming (IP) Models for Optimum Transition from Open Pit to Underground Mining Methods
TL;DR: A set of classified integer programming models for determining an optimum transition depth (OTD) between open pit and various underground mining methods is developed and it is shown that the integrated models present solutions that are practically more realistic.
21
A mixed integer linear programming framework for optimising the extraction strategy of open pit – underground mining options and transitions
TL;DR: A combined sequential and simultaneous open pit and underground (OPUG) mining with crown pillar as the optimal extraction option generating NPV that is 11% and 13% better than independent OP or UG mining, respectively.
20
Optimization of open pit to underground transition depth: An idea for reducing waste rock contamination while maximizing economic benefits
TL;DR: In this paper, an integer programming (IP) optimization model was executed on a real orebody to evaluate the amount of waste rock reduction while optimizing the transition depth of an open pit mine.
15
A Review of Models and Algorithms for Surface-Underground Mining Options and Transitions Optimization: Some Lessons Learnt and the Way Forward
Bright Oppong Afum,Eugene Ben-Awuah +1 more
- 10 May 2021
TL;DR: In this study, extensive literature review and a gap analysis matrix are used to identify the limitations and opportunities for further research in surface-underground mining options and transitions optimization for comprehensive resource development planning.
15
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