Technology for Real-Time Monitoring of Coal Dust Explosion Hazards

The NIOSH-developed Coal Dust Explosibility Meter (CDEM).
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The NIOSH-developed Coal Dust Explosibility Meter (CDEM) is now available for purchase and use in underground coal mines. This device allows for real-time testing of incombustible content on the interior surface of the mine. The new Mine Safety and Health Administration (MSHA) rule requires a minimum of 80% rock dust in all mined areas outside the return airway to prevent explosion propagation. Both the CDEM and the new MSHA rule represent the significant impact that the NIOSH Office of Mine Safety and Health Research (OMSHR) has on the mining industry.

Mine explosions remain a threat to underground coal miners, requiring constant vigilance to prevent accumulations of combustible gasses and dusts. Accumulations of combustible dust in coal mines create the risk of large-scale explosions that can result in multiple deaths and traumatic injuries. The explosion hazard can be effectively controlled through the application of rock dust, such as limestone dust, to render inert the combustible coal dust generated during the mining and transport of coal. Traditionally, determining when additional rock dust should be applied or evaluating the effectiveness of existing rock dust application has been limited to a subjective visual evaluation or collection and laboratory analysis of dust samples - a process that requires days or weeks to identify a hazard.

For decades, miners have been able to monitor the concentrations of methane and other combustible gasses using handheld, direct reading gas detectors. These detectors allow miners to take immediate action to dilute gasses and prevent explosions. With this same purpose in mind, OMSHR researchers developed the CDEM to provide instant feedback to miners on the relative hazard of dust accumulations in the mine and the effectiveness of their rock dusting practices. This simple-to-use handheld device provides a pass/fail assessment of coal mine dust samples, allowing for immediate action by operators or regulators to eliminate an explosion hazard.

Development of the CDEM required significant research by OMSHR and its predecessor program in the U.S. Bureau of Mines, in collaboration with MSHA, to identify a technology that could provide real-time results comparable to the existing laboratory test. Researchers then transferred the technology - which received the R&D 100 Award in 2006 for Innovation in Technology - from the lab setting to the field, and refined the device to pass the rigorous MSHA evaluation for intrinsic electrical safety. Attempts to commercialize the instrument over the past 10 years were unsuccessful due to a lack of market interest. Recently, Sensidyne Industrial Health and Safety Instrumentation commercialized the meter. Information on the CDEM can be found on the Sensidyne CDEM-1000 product page .