1973 4. RESULTS AND DISCUSSIONS 4.1 Controlled Blasting Near Sensitive Infrastructure The A3N pit successfully achieved safe production blasting near critical infrastructure, eliminating the need for any relocation of facilities. Throughout 2025, blasting activities displaced more than 1,016 kt of material while maintaining full compliance with the vibration limits established by NBR 9653 at the administrative buildings and adhering to the more conservative threshold of ≤ 5 mm/s at the water dam, as illustrated in Figure 128. All protected areas remained free of flyrock: during blasts in Sector I, no projections were recorded, and in Sectors II and III, the respective stand‑off limits of 50 m and 100 m were consistently respected, as shown in Figure 130. From an efficiency standpoint, the standard powder factor planned was reduced by approximately 18%. In Sector II, refinements increased MIC from 18 kg to 22 kg and reduced stemming from 4.0 m to 3.6 m, enabling roughly 50% pattern expansion and associated cost benefits while maintaining control. When combined with the avoided relocation of infrastructure, the project delivered an estimated economic impact of US$ 1.6 million. Figure 127 - A3N Pit Aerial View (dec/25) Figure 128 - Vibration Measurements (A3N) 0.1 1 10 100 1 10 100 Vibration (mm/s) Frequency (Hz) NBR9653 Water Dam Buildings
RkJQdWJsaXNoZXIy MTM0Mzk2