Comparative analysis of 3D domain modelling alternatives: implications for mineral resource estimates

Abstract

Domain modelling is a fundamental component of contemporary mineral resource estimation. There exist four major modelling techniques that are distinct with respect to method complexity, time and effort. A Comparative analysis is presented in this document constituting estimation of resources using 3D estimation domains generated with four different modelling approaches; (i) explicit modelling, (ii) implicit modelling, (iii) indicator kriging, and (iv) conditional simulation. Furthermore, identical grade estimation method and parameters are considered in order to demonstrate the discrepancies arising only from the choice of the domain modelling approach and underlying assumptions. Comparison of the outcomes indicated the significance of the domain modelling decision on resource estimates of a polymetallic massive sulfide deposit located in western Turkey. Economic implications are demonstrated in the form of range of outcomes for the extends of the ultimate pit, ore tonnages (min:37.0 Mt, max: 46.7Mt), waste tonnages (min:201.2 Mt, max: 251.2 Mt), stripping ratios (min:5.18, max: 5.71), and total pit values (min: $1.05B, max: $1.45B). The study showed that indicator kriging and simulation results are largely consistent with each other due to similar estimation criteria considered. Moreover, these two techniques resulted in notably larger volumes particularly for highly mineralized estimation domains compared to the ones generated with explicit and implicit modelling techniques. Examination of solid models as well as cross-sections revealed that major discrepancies are observed beyond outlying drillholes. Therefore, it has been proposed that assumptions regarding extrapolation distance is the main source of mentioned dissimilarities.