Combined influence of percussion and rotation pressures on the performance of drilling steels in granodiorite and sandstone rocks in an underground mine, Peru

Purpose The purpose of this study was to evaluate the influence of percussion and rotation pressure on the performance of drilling steels in different types of rock, specifically sandstone and granodiorite, in an underground mine in Peru. Design/methodology/approach The study employed a controlled experimental design, varying percussion and rotation pressures under specific geological conditions. The performance metrics, including wear and efficiency of drilling steels, were analyzed using robust regression methods to address the non-normal distribution of data. Experiments were conducted under pressures of 130 and 160 bars for granodiorite and 80 and 35 for sandstone. Findings The results indicated that drilling steels experienced greater wear and efficiency in granodiorite compared to sandstone. In granodiorite, wear on the drill body reached 3.7 mm and 2.4 mm on the inserts, with an efficiency of 2.31 m/min. In sandstone, wear was 2.45 mm and 1.15 mm, with an efficiency of 1.92 m/min. In addition, drilling costs were lower in sandstone (0.35 US$/m) compared to granodiorite (0.40 US$/m). It was concluded that both percussion and rotation pressure significantly influence the wear and performance of drilling steels, increasing wear but improving efficiency with each 1-bar increment in pressure. Originality/value The originality of this study lies in its comprehensive analysis of how percussion and rotation pressure affect the wear and performance of drilling steels in two distinct rock types: sandstone and granodiorite. The application of robust multiple linear regression provides a deeper understanding of the relationship between pressure increments and drilling efficiency, offering valuable insights for optimizing drilling operations in underground mines.