Numerical Modeling Application in the Design of Regional Pillars for an Ore-Replacement Project: Underground Platinum Mining Case Study

Abstract

ABSTRACT Pillars are critical to the stability and profitability of mining operations and their proper design is essential in ensuring that these objectives are met. A number of tools are available in designing pillars and numerical modelling is one of those tools. It is important to note that numerical modelling is not design in its self as wrongly assumed by many, but a tool that is used to aid the design process. This paper evaluates numerical modelling application in the design of regional pillars for an ore-replacement project, underground platinum mining case study, using three different numerical modelling programs. The three numerical modelling programs used in the design process were Examine 2D, Map3D and Lamodel. These programs were used to determine the average pillar stress on the designed pillars and the values obtained were then used to determine the most feasible pillar design. The results obtained were then validated by comparing them with a design based on an empirical method (Stacey and Page pillar strength equation) and underground observations. The advantages of numerical modelling versus the traditional empirical methods are that they can cater for different geometries and scenarios that were identified as limitations in the use of empirical methods. The difference in average pillar stress values obtained between empirical design and numerical modelling and indeed between the different numerical modelling programs themselves give a compelling argument that it is prudent not to base the design of any underground layout on only one method. An attempt should be made to use as many different available methods as possible, then from those, use the most optimal one in terms of cost and extraction ratio based on the design criteria. INTRODUCTION Numerical Modeling plays a key role in enhancing the confidence in designs undertaken using empirical approaches. Empirical approaches have been found to be also reliable since they are tethered in reality and can account for design parameters which may be difficult to account for using numerical modeling (Benyoucef et al, 2023; Jarufe, 2022; Li et al, 2021; Chikande and Zvarivadza, 2018; Zvarivadza and Sengani, 2018a; Zvarivadza and Sengani 2018b; Chikande and Zvarivadza, 2016; Chinyowa and Zvarivadza, 2015). A detailed study on empirical approaches in the design of regional pillars in platinum mining is given by Mutsvanga and Zvarivadza (2020).