OPEN PIT STRATEGIC IVIINE PLANNING UNDER UNCERTAINTY - ROBUST AND FLEXIBLE PLANS

摘要

A strategic mine plan is a fundamental part of any mining operation. It must provide a realistic extraction and processing schedule, as well as an accurate measure of the value of the project. There are several challenges to generating a successful strategic mine plan. Most importantly, key input information re-quired for mine planning, such as actual ore grades and market prices, is uncertain in nature, thus a mine plan generated with deterministic data has a very low probability of performing as expected. Traditional mine planning approaches and existing software packages have failed to address uncertainty, which ultimately leads to underperforming and misvalued operations. In this paper we present the first software application that successfully takes into consideration market price uncertainty and generates feasible mine plans, in a timeframe competitive with commercially available software. The methodology presented provides a platform to consider market price uncertainty without an exponential increase in computational cost. By including uncertainty, our solution is able to create robust and flexible mine plans. A robust plan is one that best performs under unstable economic conditions. A flexible plan incorporates Real Options Analysis, allowing to postpone decisions such as expanding capacity, until the uncertainty has been reduced. The software has been tested for this paper in a real 12 million block model, with a mining operation lasting over 50 years, delivering competitive results for deterministic mine plans, increasing expected NPV in 2.4% with robust plans and the expected NPV of a fictitious expansion project in 68% with flexible plans.