Development a novel empirical approach to control overbreak, surface quality and slope angle of benches following blasting

Abstract

Overbreak, slope angle and quality of a bench behind the boundary of excavation as attractive subjects for mining and civil engineers are the most crucial consequences of the post-blast. But the breakage mechanism of blasting has not originally been well clarified how a desirable slope angle and quality of a bench can be obtained by common drilling and blasting operations and what parameters can affect such blasting consequences? The breakage mechanism and influence of the blasthole parameters such as hole diameters, explosive weight per hole, burden, spacing, stemming, bench height, powder factor and blastability index on the depth of the overbreak zone (L<sub>OZ</sub>), the difference between hole and bench slope angles (α°-β°) and the width of damaged zone (L<sub>DZ</sub>) in fifteen zones of Sun gun open pit copper mine, Golgohar open pit iron ore mine, Khoy limestone, Rashakan limestone, Bonab silica mine and Evoghli gypsum mine were investigated. New multivariable nonlinear relations between each of L<sub>OZ</sub>, (α°-β°) and L<sub>DZ</sub> with the combination of Φ<sub>h</sub>, Q, B, S, S<sub>t</sub> and K were developed. The new achievements in this study can be new guides to obtain the desirable bench slope angle and bench faces.