Influence of Blasting Approaches in In-Pit Haul Road Construction on Emission Levels and Resource Management: A Case Study from the Holcim “Dubie” Open-Pit Mine

Transportation activities can constitute up to 70% of a quarry’s total operating costs, making haul roads a critical component of open-pit mine infrastructure. Generally, in-pit haul ramp construction can be accomplished through two primary blasting approaches: either peripheral blasting near the ramp location, or direct blasting at the designed ramp site. In the first method, the blasted material is transported, shaped, and compacted to form an embankment. Conversely, in direct blasting, the blast pattern is specifically designed to generate the ramp geometry, and the resulting muckpile is directed to production, eliminating the need for an embankment. Each method presents distinct operational advantages and inherent limitations. This study investigates the influence of these blasting scenarios, in particular on fume emissions (nitrogen oxides—NOx—and carbon oxides—COx) and deposit management. The assessment encompasses emissions generated both from the detonation of explosives and from the operation of diesel-powered equipment. The findings indicate that the method involving peripheral blasting (bench embankment construction method) produces more than 2.5 times higher nitrogen and carbon oxides emissions compared to blasting works at the exact construction location of the ramp at the Holcim Dubie dolomite open-pit mine. In addition to emission analysis, operational factors related to ramp formation and its subsequent use were evaluated. The results demonstrate that constructing the in-pit haul ramp directly within the rock mass yields approximately 2·106 Mg less fume emissions than the embankment-based method. Furthermore, this approach facilitates the recovery of an additional 150,000 m3 of dolomite for production purposes, thereby enhancing resource efficiency. Collectively, these findings suggest that the direct in-rock ramp construction technique offers superior environmental performance and operational sustainability within the context of open-pit mining practices.