3.2 Exploratory and variographic analysis The exploratory analysis shows that the main element, Fe, is highly homogeneous, as evidenced by the percentiles, where 90% of the data have grades between 61.41% and 66.10%. This analysis supports the idea that the tailings stored in the dam have grades of suitable quality for potential economic viability. Figure 3 – Exploratory analysis of Fe occurrence Compositing (regularization) was performed for 801 samples for Fe, SiO₂, P, Al₂O₃, and Mn, and for 529 samples for CaO, MgO, TiO₂, and particle-size fractions from +0.250 mm to −0.020 mm. A high mean Fe grade of 64.09% was observed, along with 1.97% SiO₂ and 0.12% P (Table 1). Table 1 – Iron, associated elements, and particle-size distribution of sediments in the Gelado tailings dam Variable Samples number Minimum (%) Maximum (%) Average (%) Variance (%²) Standard deviation (%) Fe 801 56,56 66,77 64,09 2,23 1,49 SiO 2 801 0,58 10,4 1,97 1,21 1,1 P 801 0,03 0,12 0,06 0 0,01 Al 2 O 3 801 0,75 4,56 2,26 0,45 0,67 Mn 801 0,32 2,06 0,81 0,06 0,25 CaO 529 0,01 0,3 0,02 0 0,01 MgO 529 0,02 0,72 0,06 0 0,02 TiO 2 529 0,04 0,3 0,17 0 0,04 +0.250 mm 529 0 27,4 1,45 9,4 3,07 +0,150 mm 529 0 15,2 1,53 4,53 2,13 +0,106 mm 529 0 18,8 2,52 8,89 2,98 +0,075 mm 529 0 25,8 5,86 34,99 5,91 +0,045 mm 529 0 36,2 9,07 72,01 8,49 -0,045 mm 529 26 100 79,57 327,66 18,1 -0,020 mm 272 0 96,59 56,62 248,39 15,76
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