A fast method to find smooth economic envelopes for block and panel caving mines

Abstract

The first step in the planning of a mine is the determination of the economic envelope, which is the volume that encapsulates the mine layout and maximizes the total economic value; thus, it has a considerable impact in the design and planning of the mining project. The most common approach for calculating the economic envelope of block and panel caving mines is to determine the best envelope for each possible floor and then chose the est from manually. This method is very fast and effective but may generate footprints that are difficult to design and operate as they do not consider any geometrical constraint of the shape of the envelope that are relevant, for example, to limit abutment stress.In this paper, we present a novel method that incorporates geometrical constraints related to the connectivity and smoothness of the outline of the envelope, and the continuity and smoothness of the height of the draw columns. Our method is based on the same approach used to compute the ultimate pit, i.e., the economic envelope of open pit mines. Therefore, it is very efficient and ensures to find the optimal solution for the constraints that are set.We test the method, comparing the economic envelopes of the de facto approach and our proposed approach and show that the geometries obtained are more favorable geometries and generate economic values similar to or better than those calculated using the standard approach. That is, the method improves the geometry of the economic envelope without loss in value.