By Joe Defibaugh, engineer-dust and ventilation, Komatsu Mining Corp.; Hugo E. Camargo, principal engineer, NOISH; and Lynn A. Alcorn, engineering technician, Centers for Disease Control and Prevention

NIOSH conducted research to develop noise controls for longwall mining systems. Previous research determined that the dominant sound-radiating components on a longwall shearer are the two cutting drums. Therefore, NIOSH developed numerical models of these drums to predict their dynamic and acoustic responses. Upon validation, the models were used to explore various noise control options including force isolation, increasing structural damping, and increasing the stiffness of the vanes. The most practical solution was to increase the stiffness by adding gussets, and to increase the thickness on the outermost helical vane plates. A set of modified drums were built and tested at a mine in New Mexico. Results test showed noise reduction across the entire frequency spectrum with overall noise reductions of around 3 decibels.