Application of Present Value-Volume (PV-V) and NPV-Cumulative Total Ore (NPV-CTO) fractal modelling for mining strategy selection

Open pit mine planning and determination of mining orientation are a critically important part of a mine opening to its closure. However, an optimal extraction sequences (OES) is identified when an NPV cumulative trend becomes steady. This is controlled manually, typically from a nested pit shell methodology based on the experience which can lead to suboptimal results. Given this problem, a mathematical method to provide an analytical practice, which intends to prevent manual identification of an OES seems to be inevitable. The aim of this study is to propose Present Value-Volume (PV-V) and NPV-Cumulative Total Ore (NPV-CTO) fractal models to identify an accurate excavation orientation as well as an OES with respect to economic principals and ore grades. This has been conducted to achieve an earlier pay-back period and highest cumulative NPV in Kahang Cu-Mo porphyry deposit, central Iran. Results derived via the PV-V fractal modelling indicate an accurate mining orientation with an N-S trend. Thus, pit sequence No. 92 was selected as the closure of the open pit mining for the Kahang deposit. Consequently, the NPV-CTO fractal model provides an analytical tool which can be used for determination of an OES for an open pit mine.