Technologies For Continuously Monitoring Respirable Coal Mine Dust

The Federal Mine Safety and Health Act of 1977 requires mine operators to periodically sample mine atmospheres to determine compliance with the Federal respirable dust exposure standard. To do so, mine operators use gravimetric samplers that are approved by the Mine Safety and Health Administration (MSHA), Department of Labor. However, the gravinistric approach with its inherent delays cannot provide dust level data quickly enough to allow on-site correction of inadequate dust control strategies or removal of personnel from harmful environments. Furthermore, alleged tampering with dust samples collected to determine compliance with the standard prompted the Secretary of Labor to appoint a special Respirable Dust Task Group to study options to improve monitoring and control of respirable coal mine dust. MSHAs Task Group recommended that the U.S. Bureau of Mines (USBM) develop a fixed-site monitor that will provide continuous information to the minor and mine operator regarding dust levels and the status of compliance with the applicable respirable dust standard. In response to MSHAs request, the USEM is investigating several technologies for monitoring respirable dust. These technologies include resonant frequency decrement, beta attenuation, continuous dust pyrolysis, and differential pressure across sampling filters. This paper describes these technologies, discusses possible applications, and summarizes the current status of these investigations.