Experimental research and energy analysis of a new type of dry ice powder pneumatic rock breaking technology

• Published in: International journal of mining science and technology Vol. 33; no. 4; pp. 423 - 435
• Main Authors: Wang, Xiaofei, Hu, Shaobin, Wang, Enyuan, Zhang, Qiang, Liu, Bing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-04-2023; Elsevier
• Subjects: Cracking mechanism; Dry ice powder pneumatic rock breaking; Energy analysis; Vibration frequency; Dry ice powder pneumatic rock breaking; Energy analysis; Vibration frequency; Cracking mechanism
• ISSN: 2095-2686
• DOI: 10.1016/j.ijmst.2022.12.010

When the traditional drill and blast method is applied to rock crushing projects, it has strong vibration, loud noise and dust pollution, so it cannot be used in densely populated areas such as urban public works. We developed a supercritical CO2 true triaxial pneumatic rock-breaking experimental system, and conducted laboratory and field tests of dry ice powder pneumatic rock-breaking. The characteristics of the blast-induced vibration velocity waveform and the evolution of the vibration velocity and frequency with the focal distance were analyzed and discussed. The fracturing mechanism of dry ice powder pneumatic rock breaking is studied. The research results show that: (1) The vibration velocity induced by dry ice powder pneumatic rock breaking decays as a power function with the increase of the focal distance; (2) The vibration frequency caused by dry ice powder pneumatic rock breaking is mainly distributed in 1–120 Hz. Due to the dispersion effect, the dominant frequency of 10–30 Hz appears abnormally attenuated; (3) The traditional CO2 phase change fracturing energy calculation formula is also applicable to dry ice pneumatic rock breaking technology, and the trinitrotoluene (TNT) equivalent of fracturing energy is applicable to the Sadovsky formula; (4) Dry ice powder pneumatic rock breaking is shock wave and high-energy gas acting together to fracture rock, which can be divided into three stages, among which the gas wedge action of high-energy gas plays a dominant role in rock mass damage.