Estimativa de incerteza e otimização da malha de sondagem por simulação condicional em um depósito de bauxita do distrito de Paragominas, Pará-Brasil

Abstract

Errors or uncertainties in estimating mineral resources can compromise strategic planning and mineral processing decisions or make a mining project unfeasible. In this sense, to assess the degree of uncertainty and risk quantification associated with different drilling grids, DHSA (Drill Hole Spacing Analysis) methodology was used, based on conditional simulation by Turning Bands Simulation (TBS) with implementation in the software Isatis.neo Mining Edition®. Uncertainty related to the reactive silica (SIRE) estimates was investigated from multiple equiprobable scenarios for the mineralized zone (Crystalized Bauxite - BC and Crystallized Bauxite/Amorphous Bauxite - BCBA) of a bauxitic deposit located in the Bauxitic Province of Paragominas (PBP) - Pará, Brazil. The study demonstrated that the classification criteria currently used, especially the one associated with the geometry of the drilling grids, is conservative in relation to Harry Parker’s criterion and that the ideal drilling spacing for classifying mineral resources would be 600 m × 600 m for Indicated Resources and 300 m × 300 m for Measured Resources. These results can be used to review the classification criteria and in decision-making regarding the need or not for new drilling campaigns for the conversion of mineral resources.