Operator noise exposure reduction using coated conveyor chain flight bars

Abstract

Continuous miners are one of the fundamental machines used to cut, gather, and remove coal and noncoal minerals from underground room and pillar mining facilities. These machines are among mining equipment that generates the highest sound levels in an underground environment. The Mine Safety and Health Administration has determined that continuous mining machines rank first among all equipment in underground coal mining whose operators exceed 100% noise dosage. The conveying system is one of the principal noise sources on continuous mining machines, due to metal on metal impacts that occur between chain flights and the conveyor deck. A highly durable polyurethane coating has been developed by NIOSH for the chain flights to decrease noise generated by these impacts. A continuous mining machine retro-fitted with coated flight bars have achieved overall sound level reductions of 5–7 dB(A) in a laboratory setting (Kovalchik et al., 2004). This research describes the effectiveness of this engineering noise control in reducing the noise exposure of continuous mining machine operators in an underground environment. Results show that continuous mining machine operators receive a 3 dB(A) time-weighted average reduction over an 8-h period.