The National Institute for Occupational Safety and Health one year pilot study will look to develop an improved technique to identify and accurately measure prevalent noise sources on a longwall system – no small undertaking considering varying mine environments and factors such as production levels, equipment operation and equipment position.
The project will eventually look at developing engineering noise control technologies that could be applied to the stageloader and shearer to reduce noise emissions.
If all goes well, NIOSH will then look at implementing controls in partnership with manufacturers through future research endeavors. Already on board for the project are producers Consol Energy, Eastern Associates and Peabody Energy and OEMs DBT America and Joy Mining Machinery.
The first four months of the project will involve establishing a measuring methodology. This will include defining parameters that affect noise measurements on a longwall; visiting a longwall site to perform preliminary testing; collecting initial data to determine the most accurate methods to collect noise data; and developing guidelines to measure noise levels on a longwall mining system.
While no mines have been selected at this stage, NIOSH hearing loss prevention branch chief RJ Matetic said two mines in southwestern Pennsylvania and one mine in either New Mexico or Colorado would become the cooperative sites.
The second four months of the project will be spent taking measurements to define and rank the noise sources. This will involve visiting two or more longwalls to collect data on specific noise sources on the longwall stageloader and shearer.
This data will then be analyzed and a list of potential engineering noise controls for the shearer and stageloader made. The controls will be ranked according to relative cost, practicality, functionality, ease of implementation and worker acceptance.
Matetic said while the overall noisiest parts of the stageloader and shearer were generally known – such as the discharge, AFC drive and crusher sections on the stageloader, and the cutter drums on the shearer obtaining accurate information that can be used to develop optimum controls was extremely difficult in an operating mine environment.
NIOSH has decided to use dosimeters as its “noise loggers”, which will be used as stationary sound level meters and placed in pre-selected arrays along and above the stageloader and on selected shield supports along the longwall face to monitor the shearer as it passes. Matetic said a large part of the research effort was determining how to accurately measure the noise generated and then conducting field monitoring tests to measure it.
The project is a high priority for NIOSH with noise induced hearing loss as one of the 10 leading work-related diseases and injuries in the US. NIOSH studies have found nearly 50% of the full-shift dose measurements of longwall face workers exceeded the MSHA-PEL (Permissible Exposure Level) of more than 90dB on average over eight hours. Ninety decibels is equivalent to what an average motorcycle or small lawn mower may sound like in normal operation.