Table 2 – Coefficient “K” determined at 95% reliability from the ground attenuation law at 50% confidence. Source: Orica Blast Engineering. Site Law Coefficients Site Coefficient 50 % Confidence 95 % Confidence K 1909.83 4820.30 -α -2.01 -2.01 Standard Error 0.21 Therefore, the 50% and 95% reliability curves were obtained, as shown here: Figure 5. Scatter plot with attenuation laws at 50% and 95% confidence. Source: Orica Blast Engineering. Based on the above, the ground attenuation law is used with a 95% reliability level because, under this constraint, the value of the maximum instantaneous charge (MIC) can be determined, thus avoiding the use of excess charge for the required blasting energy. Therefore, we have the following attenuation law: VPP = 4820.30 x( DඥQ )−2.01 Seeing that the obtained law presents a higher prediction than the first (K95% > K50%), it was validated with the results of the blasting design executed on site. 2.6 Drilling Quality Control The quality of the drilling process significantly influences downstream mining and processing operations, including rock fragmentation and ore recovery rates. Uncontrolled drillhole deviation often results in poor blast performance, excessive overbreak, dilution from adjacent cemented hydraulic fill walls, reduced stope recovery efficiency, potential geomechanical instability in exposed walls and increased operational costs.
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