Mining Publication: Evaluation of Stiffeners for Reducing Noise from Horizontal Vibrating Screens

Sound levels around vibrating screens in coal preparation plants often exceed 90 dB(A). The National Institute for Occupational Safety and Health (NIOSH) is developing noise controls to reduce noise generated by horizontal vibrating screens. NIOSH researchers used finite element analysis (FEA) and a NIOSH-written program to estimate the sound power level reduction resulting from adding rib stiffeners to key locations on the sides of a screen. The researchers evaluated adding rib stiffeners made from steel channel with two different cross-sections (C and T) and the effects of orienting the stiffeners horizontally and vertically. In addition, the researchers investigated the effects of increasing the modal damping from 0.002 to 0.010. The results indicate that for a broadband input, adding stiffeners had little impact on the estimated sound power level, but increasing the modal damping reduced the predicted A-weighted sound power level by 7.8 dB.