Mining Publication: Acoustic Assessment of Pneumatic and Electric Jackleg Drills used in the Mining Industry

• Exposure tracking
• Jack-leg drills
• Noise
• Sound power level

Hearing loss is the most prevalent disease among miners. A study of U.S. western hardrock mines revealed that 96% of machine operators were overexposed to noise, with jackleg drill operators having the most rapid noise dose accumulation. Traditionally, jackleg drills have been driven by pneumatic power. However, there are currently available rotary hammer drills powered by electricity. This paper presents an acoustic assessment of pneumatic and electric jackleg drills that involved Noise Source Identification (NSID), penetration rate measurements, operator’s cumulative noise dose measurements, and the determination of sound power levels. NSID using beamforming array technology revealed two dominant noise sources for the electric drill, one located at the drill and one located at the drill steel-rock interaction place. In contrast, NSID for the pneumatic drill showed only one dominant noise source located at the drill. Penetration rate and noise dose measurements were combined to estimate the accumulated dose and time required to drill a reference depth hole. Sound power level measurements while drilling into granite yielded overall levels of 115.3 dB(A) and 123.4 dB(A) for the electric and pneumatic drills, respectively. The results show that from an occupational noise exposure perspective the acoustic performance of the electric drill, despite its slower penetration rates, overcomes the benefits of traditional pneumatic drills.