Change of support based on modified localized uniform conditioning and direct block multivariate simulation on the Sungun porphyry deposit, Iran

Mining operations are planned and designed based on block models. A fundamental parameter of this type of model is the choice of block dimensions or selective mining unit (SMU) size, which affects the operation and mining costs. In the early stages of mining operations, the available information is mainly drill holes samples, which may bring negative outcomes such as over-smoothed models, especially for complicated ore deposits. Therefore, a change of support is necessary to determine the distribution of grades at an equivalent volume to the SMU size. The nonlinear localized uniform conditioning (LUC) and direct block simulation (DBSIM) methods are appropriate for optimal grade estimation of small blocks, when the input data spacing is excessively coarse. This paper presents an extension of the LUC method, incorporating the DBSIM in order to change the support on the Sungun porphyry deposit in Iran. Multiple realizations of Cu, CuO, and Mo grades are generated for the dimensions of 30x30x15 m3, 25x25x12.5 m3, and 20x20x10 m3, respectively. Comparing the standard methods, the modified method proposed in this paper presents a more reliable spatial distribution of attributes and an acceptable conformity with the true data of the Sungun deposit.