3201 A Formulation for Optimum Risk in Open Pit Mining
DOI:
https://doi.org/10.17159/Abstract
The selection of open pit slope angles are high value decisions with small changes in slope angle often representing significant changes in Net Present Value. The existing methods used to define Design Acceptance Criteria have evolved from Factor of Safety, to Probability of Failure (P[F]), to Risk Consequence to Risk Frontiers, which, represents the current state of the art. The current design acceptance measures are based on references to published tables representing the experience and judgement of their authors, who did not specify the purpose of the design acceptance measures contained therein. As the purpose of the published design acceptance criteria is not specified (i.e. definite stability, marginal stability, optimisation etc.), such tables cannot be used to achieve optimum slope angles that maximise profitability. This paper develops a Design Acceptance Criteria maximising profitability by defining a formulation for Optimum Risk that balances expected risk and reward. The model developed is titled the Mining Risk Model (MRM), and is applied to open pit slope angle selection through an equation for Optimum Probability of Downside (P[D]O) balancing the Upside or opportunity, the P[F] and the Downside impact. This Formulation for Optimum Risk, is unique as many authors presented objective functions for their risk models that can be optimised, but none of the sources reviewed, contained a formulation for optimum risk.
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Copyright (c) 2024 Julian Venter, Johan Wesseloo, Bryan Maybee
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