Optimal Economic Envelope of Joint Open-Pit and Underground Mines

Abstract

The costs and complexity of the mine operation increase as extraction in an open pit mine progresses, making the use of underground methods more and more appealing. A natural question is, therefore, what are the boundaries of the open pit and the underground sections of the mine that maximize the economic value of the mining operation? A few attempts have been made to answer this question, ranging from simple approaches that consider scheduling the open-pit section and the underground section sequentially, to more complex approaches that simultaneously schedule both sections at different aggregation levels. The main focus of these works has been determining the optimal transition time. In this work, we focus more on the definition of the economic envelope of the mines rather than time. Our motivation for this is the robustness of this decision. We present a mathematical model and an algorithm to jointly determine the optimal envelops of the open pit and underground sections of the mine.