Strong Mining Pressure Danger-breaking Technique by Liquid CO₂ Phase Transitions Blasting in Tingnan Coal Mine

Liquid CO₂ phase transitions blasting gear is used to carry out pressure relief and blasting for solving rock burst phenomenon of coal pillar at 206 working face return airway in Tingnan Coal Mine. We research the laws of strong mine pressure phenomenon at 206 working face return airway, and set out blasting schemes and parameters design. After blasting, drilling cuttings weight decreased to critical value below, the average value of drilling cutting weight within 2 m to 6 m was 2.45 kg/m and within 7 m to 10 m wass 2.78 kg/m; coal stress decreased from 20 MPa to 15 MPa; average energy of microcosmic events fell to 3.5×10⁴ J below for each day with obvious pressure relief effect.