Investigation of effect of CO2 laser parameters on drilling characteristics of rocks encountered during mining

Abstract

Application of laser technology for drilling rock samples reduces mining costs because of its higher transmission capabilities providing an alternative to conventional drill bits and blasting techniques. This paper investigates the effect of laser drilling parameters such as laser power, frequency, assist gas pressure and piercing time on drilling characteristics of rock mineral samples such as limestone, shale and sandstone using 12 kW CO2 Laser. For limestone, minimum specific energy of 46.14 kJ/mm3 and maximum rate of penetration 15.14 mm/s was achieved at 1000 W laser power, 1 kHz frequency, 6 bar assist gas pressure and 0.1 s piercing time. For sandstone, minimum specific energy of 14.33 kJ/mm3 and maximum ROP of 57.46 mm/s was achieved at 1000 W, 1 kHz, 2 bar and 0.1 s. For shale, minimum specific energy of 8.13 kJ/mm3 and ROP of 45.05 mm/s was achieved at 300 W, 5 kHz, 2 bar and 0.1 s, based on Response Surface Methodology. Morphological studies were reported on the drilled rock samples. Keywords: Laser drilling, Specific energy, Rate of penetration, Rock minerals, Response surface methodology