Mining Contract: Reduction of Noise Exposure in Underground Mines by Improving Auxiliary Ventilation Technologies

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Contract #	200-2015-63540
Start Date	9/1/2015
End Date	10/31/2017
Research Concept	This technology will focus on developing auxiliary ventilation systems that can still provide the necessary air flow without generating noise levels that create overexposure to mine workers.
Topic Area	Hearing Loss Prevention Overview

Contract Status & Impact

This contract is complete. To receive a copy of the final report, send a request to mining@cdc.gov.

This contract aims to reduce noise exposure in underground mines by improving auxiliary ventilation technologies. Noise-induced hearing loss (NIHL) is an inherent health hazard in the mining industry, specifically in mines where heavy pieces of equipment are being utilized. Reduction of noise generated by mine fans can prove to be a significant step towards addressing this problem. While mine equipment is being operated, noise levels are elevated by the use of portable auxiliary fans, which are used to keep the mine ventilated. At times, multiple fans in series are used, further enhancing the noise level. Ventilation systems are usually designed for high efficiency with minimal emphasis placed on noise reduction. Sound attenuating devices are used, but are bulky, inefficient, and often omitted. This research will develop and test improved fan silencers.

In underground mines, working areas can be filled with extensive and damaging noise. When portable underground fans are used, either as auxiliary or booster fans, noise usually comes from two sources: fan motor and impeller blades. Without the presence of silencers, sound pressure at hazardous levels in excess of 100 dB(A) have been measured. Research has shown that the noise level can be reduced when flexible silencers are connected to both ends of the fan. However, the silencers can become clogged and ineffective if not properly maintained.

Under this contract, the University of Utah has assembled an auxiliary ventilation model equipped with flexible couplings and silencers to reduce noise level. This model has currently been upgraded to include two axial fans of 0.45-m-diameter ductwork in series. A 10 HP fan with two types of silencers has been purchased. This fan was tested in the field using three configurations: alone without a silencer, with a strut silencer, and with a ring silencer. To date, the ring silencer has provided the best noise reduction. In addition, the newly redesigned silencers have a potential for commercialization since they constitute an add-on feature to the portable ventilation fans.