A Model for Determining Optimal Transition Depth over from Open-Pit to Underground Mining

Abstract

In this paper, the authors consider to the deposits which have potential for exploiting initially by Open Pit (OP) method, and as it is proved to greater depths, the pit is planned to transfer to Underground (Ug) mining methods. The most significant problem connecting to the deposits is determination of optimal Transition Depth (TD) from OP to Ug mining. Here, a heuristic algorithm as a basic model based on Block Economic Value (BEV)s of OP and Ug was represented. Initial part in the model is, recognizing mineable main blocks of 50*50 m due to the both mining methods and comparison between sum of OP and Ug main block values in each main level from upper to lower, respectively. To increase accuracy and capacity of the model, the final main level of OP is imperative to separate to sub-levels and related sub-blocks of 12.5*12.5 m. The performed stages of the algorithm for main levels and blocks must be supplied for the sub-levels and sub-blocks, too. To state the model in detail, it was employed as a tool for determining the optimal transition depth and total profit in the combined method of OP and Ug for a hypothetical deposit.