Field evaluations of a noise control for roof bolting machines

Abstract

Roof bolting machine (RBM) noise is a significant health hazard in underground coal mining because the sound levels at the operator’s station often exceed 100 dB(A). Drilling the hole prior to installing a roof bolt is the most significant source of RBM operator noise exposure. The dominant source of drilling noise is the drill steel. NIOSH has developed an enclosure to surround the drill steel as it is drills the hole to reduce the noise reaching the machine operator. The collapsible drill steel enclosure, or CDSE, is designed to collapse upon itself as the drill steel is further advanced into the mine roof so the drill steel can remain enclosed during the entire hole-drilling process. Original versions of this device effectively reduced noise exposure, but were deemed unacceptable by the mining community due to various usability and durability issues. A modified version has been developed and NIOSH laboratory tests revealed a 2–4 dB(A) noise reduction. This paper describes the in-mine evaluation of the redesigned CDSE. The field tests focused on the noise reduction as well as miner acceptance of the device. The results confirm improved usability as well as a 42% reduction in noise dose at the operator position.

Cochrane method for systematic review and meta-analysis of interventions to prevent occupational noise-induced hearing loss – abridged

“…Additionally, 12 case studies were collected reporting on 107 uncontrolled studies of engineering control interventions (43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54) . In most cases (41) , authors evaluated design changes, followed by installing damping material and silencers (21) , purchasing new equipment (17) , using enclosures (15) , installing acoustic panels and curtains (13) , and maintenance only (7) .…”

Prevalence of hearing loss among noise‐exposed workers within the Mining and Oil and Gas Extraction sectors, 2006‐2015

“…In addition to regulatory measures, successful noise‐reducing equipment and methods have been developed/identified within Mining. Engineering controls, such as modified tail sections of continuous mining machines, noise control packages for vibrating screens, applying noise barriers and absorptive treatments within talc processing plants, drill bit isolators for roof bolting machines, structural modifications to cutting drums of longwall shearers, and noise control packages for vibrating screens, have shown to decrease noise emitted by equipment, while also maintaining durability. A 2009 study found that new‐style haul truck cabs used in limestone mines were significantly quieter (65.1 dBA) than old‐style (84.8 dBA) and retro‐fitted cabs (84.9 dBA) with the windows closed .…”

“…Recently developed engineering controls have shown great promise in reducing equipment noise within mining . Incorporation and continued development of these technologies, both in Mining and OGE, is critical for reducing worker exposures, in addition to employing effective administrative controls.…”

NIOSH Hearing Loss Prevention Program for Mining

“…Underground testing of the drill bit isolator showed noise levels at the operator's location were reduced by 3 dB when compared to baseline drilling. 12 Additional engineering noise controls that NIOSH has developed include the following: Partial cabs for surface water well drills. Collapsible drill steel enclosure for roof bolting machines.…”

“…Underground testing of the drill bit isolator showed noise levels at the operator's location were reduced by 3 dB when compared to baseline drilling. 12 Additional engineering noise controls that NIOSH has developed include…”