NIOSH proposes new rock dusting standard for coal mines
A NIOSH report (.pdf file) issued last week outlines the agency's investigation and subsequent recommendation for a new rock dusting standard to prevent coal dust explosions in intake airways.
Existing regulations from the Mine Safety and Health Administration mandate at least 65 percent incombustible content in intake airways and at least 80 percent in return airways. Based on surveys and large-scale explosion tests, NIOSH recommends a new standard requiring 80 percent total incombustible content for intake airways of bituminous coal mines in the absence of methane.
According to NIOSH, the original limits were based largely on surveys of coal dust particle sizes from the 1920s. Newer research shows coal mine dust today is much finer than in the 1920s, which NIOSH attributes to the increase in mechanization.