768 understand the distribution of grades of the main and associated metals and the particle-size fractions in the tailings dam. Aquino et al. (2025) suggest using geostatistical methods for planning mineral extraction. Isaaks & Srivastava (1989) suggest using the Ordinary Kriging method. 2. CASE STUDY THE GELADO TAILING DAM The Gelado Tailings Dam is located within the Serra Norte Complex, in the Serra dos Carajás, in the southeastern region of the state of Pará. The complex is approximately 750 km from Belém, the state capital, and about 30 km from the municipality of Parauapebas, the region’s main urban center. Access to the area is via Highway PA-275, first passing through the gate of the Carajás National Forest and then through the Vale – N5 gate. From that point, travel to the Gelado Tailings Dam takes place via internal roads within the complex, along an approximate route of 21 km. 2.1 Study methodology The study methodology was developed to meet the objective of understanding the occurrence of iron and other associated elements such as SiO₂, P, and others, as well as the particle size distribution of the material deposited in the Gelado tailings dam. It consisted of: geological modeling of the tailings body based on drillhole samples and topographic surfaces, to constrain the base, top, and boundaries of the geological body; data analysis, compositing (regularization), treatment, and statistical validation; spatial continuity analysis through variography, for estimating grades and particle-size ranges using the ordinary kriging method; and finally, resource quantification by analyzing and interpreting the estimated block model. 2.2 General characterization of the Gelado Tailings Dam The dam has a geometry composed of the main body and Arms 1, 2, 3, 4, and 5 (Figure 2). For this case study, a database consisting of two drilling campaigns carried out in 2001 and 2010 was used, using the Standard Penetration Test (SPT) method. In total, there are records of 306 drillholes and 801 samples, with assays for Fe (iron), SiO₂ (silica), P (phosphorus), Al₂O₃ (alumina), Mn (manganese), CaO (calcium oxide), MgO (magnesium oxide) and TiO₂ (titanium dioxide). Neither drilling campaign recorded density measurements, and the project assumed that the tailings have an average density of 2.50 t/m³. Figure 2 – Distribution of drillholes
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