Forecasting the grade-tonnage curves and their uncertainty at the Mehdiabad deposit-Yazd, central Iran

The Mehdiabad complex deposit is located 116 km SE of Yazd, in the structural zone of central Iran. At this deposit, important decisions are often based on the grades of multiple elements (zinc, lead, and silver). In this context, it is therefore essential to devise a method that addresses the change of support from the data support to the target smu block, the multivariate nature of the ore control selection criteria and the uncertainty in the actual (unknown) block grades. The solution presented in this study is to employ block-support sequential co-simulation to construct multiple realizations or outcomes of the grade distribution within the deposit that reproduce the natural variability at all spatial scales. The set of realizations allow assessing both grade and tonnage uncertainties and can be used to evaluate the uncertainty on key aspects of the project and transferring uncertainty of the resource/reserve estimates into risk in downstream studies.