579 In areas classified as type III rock, the tracking loading technique was used, while in type IV rock the use of control explosives was chosen. Both strategies were previously supported by energy distribution simulations, which allowed the blasting parameters to be adjusted according to the type of rock mass. Field validation showed a significant reduction in overbreak, as well as an improvement in the stability of the perimeter contour. In quantitative terms, there was a 43% decrease in overbreak, going from an initial value of 30% to 17.1%, which confirms the effectiveness of the control strategies applied during the execution of the 100 shots analyzed (see Table 5). Table 5 – Results of the average monthly overbreak. Month Overbreak March 40.0% April 12.9% May 14.8% July 19.1% August 18.5% September 16.0% October 14.0% Average 17.1% Figure 11 – Advance and efficiency per shot blasting of 28 feet. 9. FRAGMENTATION The resulting degree of fragmentation was technically controlled by sporadic sampling of monitored gunshots, obtaining an average P80 value of 6.7 inches. This result is considered technically acceptable for linear forward blasting. Table 6 – Fragmentation Control Blasting 28 Feet Fragmentation % Passing Cx653010 Cx653017 Cx677010 Rp5970 Rp677010 Cx677011 Cx69961 Cx69941 Media (in) P(10) 0.15 0.82 0.98 0.78 0.83 0.62 0.59 0.66 0.75 P(20) 0.39 1.43 1.75 1.30 1.48 1.13 1.13 1.23 1.36 P(30) 0.72 2.04 2.51 1.80 2.12 1.65 1.70 1.81 1.99 P(40) 1.15 2.67 3.31 2.31 2.80 2.21 2.33 2.43 2.65 P(50) 1.70 3.37 4.19 2.85 3.54 2.82 3.04 3.12 3.39 P(60) 2.45 4.15 5.19 3.45 4.39 3.53 3.87 3.93 4.24 P(70) 3.48 5.10 6.40 4.17 5.42 4.39 4.91 4.92 5.28 P(80) 5.08 6.35 8.01 5.09 6.78 5.55 6.31 6.25 6.67 P(90) 8.08 8.31 10.55 6.52 8.93 7.40 8.62 8.40 8.89 30.0% 17.1% 0.0% 5.0% 10.0% 15.0% 20.0% 25.0% 30.0% 35.0% 40.0% 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 Overbreak Advance per blast (m) Efficiency & Overbreak Actual advance Overbreak MB Overbreak Average Overbreak
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